HK1116512B - Systems, methods, and compositions for production of synthetic hydrocarbon compounds - Google Patents

Description

Systems, methods, and compositions for producing synthetic hydrocarbon compounds

Technical Field

The present invention relates generally to the field of hydrocarbon compound production, and more particularly, to energy efficient methods and systems for producing hydrocarbon compound fuels. In a preferred embodiment, the present invention relates to an apparatus and method for converting electrical energy into hydrocarbon compound fuels, such as gasoline, kerosene, jet fuel and diesel, among others, and produced by recycling the combustion products-carbon dioxide and water.

Background

Although the concept of developing synthetic hydrocarbon fuels has been discussed for at least 30 years, the production of hydrocarbon fuels is not required due to the availability, ease of production, transportation and handling of fossil fuels. However, the worldwide fossil fuel market is changing due to a number of factors, including a steady increase in the world's energy demand, an increase in the production intensity of oil production areas, and an increase in the emphasis on the importance of energy supply by oil-dependent countries.

The use of fossil fuels has several disadvantages as follows. First, the amount of fossil fuel available is limited and cannot be regenerated once used. In addition, hydrocarbon fuels made from fossil fuels can contain large amounts of undesirable sulfur, nitrogen, and aromatic compounds. When these fuels are burned, sulfur, nitrogen and particulate matter are released into the air, which results in the formation of acid rain and smog. Recently, attention has been focused on carbon dioxide emissions from fossil fuel combustion as a cause of global warming.

There are several mature methods for the direct hydrogenation of gases such as carbon monoxide or carbon dioxide to produce hydrocarbon fuels. One of the most successful processes was developed in germany in 1920 by Franz Fischer and Hans tropch.

In 1938, early German plants produced about 5 million barrels per year of diesel and gasoline using a Fischer-Tropsch process that reacted carbon monoxide with hydrogen over a catalyst to produce liquid hydrocarbons and water. A problem with this and other processes is that they use fossil fuels such as coal or natural gas to produce carbon monoxide. The use of such fossil fuels as primary feedstocks is associated with a number of the same deficiencies as fossil fuel production, such as limited supply and emissions.

Thus, it can be seen that there is a long felt need for a production system that recycles combustion products into hydrocarbon compound fuels. The present invention generally relates to such a system and method for the production of hydrocarbon compounds with a view to energy savings.

DE20320020U1 discloses a system for producing diesel fuel and cement, which comprises a nuclear power plant for generating electricity, a plant for electrolyzing water using electricity, a cement plant (which produces carbon dioxide), a reverse water gas balance reactor (which produces carbon monoxide and water from carbon dioxide and oxygen), and a fischer-tropsch reactor (which produces diesel fuel from carbon monoxide and hydrogen). There is no teaching of how to vary the temperature and pressure of the gases entering each reactor and how to separate the reactants at the reactor outlet. There is no teaching of how to combine a nuclear power plant, an electrolyser plant, a reverse water gas balance reactor and a fischer-tropsch reactor to apply the thermal energy generated or required in one plant, reactor or process step to be supplied or transported in another plant, reactor or process step, with the only exception being the production of cement from the low boiling point hydrocarbons produced in fischer-tropsch synthesis.

DE19522083a1 discloses as an example the production of hydrocarbon fuels from stone and seawater. The electric and thermal energy sources are renewable energy (wind, water, and solar). The carbon source is magnetite, which separates out carbon dioxide when heated to above 400 ℃. Hydrogen is produced from seawater by electrolysis. The carbon dioxide and hydrogen are compressed to 85bar and converted to hydrocarbon fuels at temperatures above 250 ℃.

US 6306917B1 discloses an apparatus and a process for producing electricity, liquid hydrocarbons and carbon dioxide from a heavy feedstock, i.e. generating electricity from steam by means of a partial oxidation reactor producing synthesis gas, a fischer-tropsch reactor converting said synthesis gas into hydrocarbon products and a tail gas containing hydrogen and carbon dioxide, and a combined cycle apparatus recovering heat from the reactor and the combustible tail gas. More specifically, the gasifier is fed with feedstock, oxygen and water, and, if present, natural gas. The outlet of the gasifier is connected via a line to an acid gas removal unit which is connected via a line to a fischer-tropsch reactor. The outlet of the fischer-tropsch reactor is connected via a line to a hydrocarbon recovery unit which separates the hydrocarbon product from the fischer-tropsch tail gas. A heat exchanger is provided in the fischer-tropsch reactor at the outlet of the gasifier and at the outlet of the fischer-tropsch reactor. The steam produced in these heat exchangers feeds a combined cycle for power generation which also feeds the gas from the gasifier and the hydrocarbon recovery unit, wherein the amount of gas fed to the combined cycle depends on the control parameters of the overall system.

Disclosure of Invention

It is an object of the present invention to provide a method and system for the efficient production of hydrocarbon compounds.

A solution of the method to achieve this object is achieved by the method of claim 1.

One solution of the system for achieving this object is achieved by the system of claim 13.

The appended dependent claims relate to advantageous further developments of the subject matter of the respective independent claims.

The present invention includes systems, methods, and compositions for producing synthetic hydrocarbon compounds, particularly hydrocarbon compounds that can be used as fuels. Typically, the carbon oxides, carbon monoxide or carbon dioxide are converted to one or more hydrocarbon compounds containing carbon and hydrogen, including but not limited to diesel, gasoline, jet fuel, liquefied petroleum gas or compounds present in natural gas. One particular method includes the steps of: a hydrogen gas stream is formed using electricity, and at least a portion of the carbon monoxide present in the carbon monoxide stream is converted to hydrocarbon compounds in the presence of at least a portion of the hydrogen from the hydrogen gas stream.

In a preferred embodiment of the system with carbon dioxide input, the amount of electrical energy input required to convert carbon dioxide to high heating value output hydrocarbon compound combustion energy ranges between 1.4 and 1.1. In another preferred embodiment of the system with a carbon monoxide input (thereby eliminating the need for carbon dioxide to be converted to carbon monoxide), the external electrical energy required to convert carbon monoxide is between 0.64 and 0.84 of the high heating value of the hydrocarbon compounds. In other words, in one embodiment of the invention, using carbon dioxide as an input, will require more electrical energy than the high heating value of the combustion of the produced hydrocarbon compounds. In another embodiment of the invention, using carbon monoxide as an input, less electrical energy will be required than the high heat value of combustion of the hydrocarbon compounds produced.

In accordance with one aspect of the present invention, it is possible to produce fifty thousand gallons of fuel per day or even more in one plant, with sufficient electrical energy, carbon monoxide and/or carbon dioxide available.

One aspect of the invention includes systems and methods that include an electrolyzer and a fischer-tropsch reactor, and in certain embodiments, a reverse water gas shift reactor for producing hydrocarbon compounds. The present invention includes a method and system for producing hydrocarbon compounds, the method and system comprising the steps of: converting at least a portion of one of the carbon oxides, including but not limited to carbon monoxide, to hydrocarbon compounds via a fischer-tropsch process in the presence of at least a portion of the hydrogen stream; and transferring at least a portion of the excess heat from the fischer-tropsch process to one of the other process steps in the process or system, to a portion of the process or system requiring energy, or to one of the other units in the system, such as to an electrolyzer or a reverse water gas shift reactor.

In the present invention, there are numerous places where it is necessary to separate certain gases from a gas mixture, or for example, gas parameters such as temperature and pressure must be changed to make one or both of these compatible with upstream or downstream processes. In the present invention, these separations or changes to the gas consume a large amount of energy. A novel aspect of the present invention is that energy transfer can be performed in the present invention to meet the energy requirements of gas separation and change.

One advantage of the present invention is its energy efficient gas treatment. There are generally two energy efficient thermodynamic methods for gas treatment. The first is an adiabatic process when all the external work is converted to or from gas energy. The second is an isothermal process when all the external work is converted to or derived from heat. Recycling external work through the electrical distribution lines and heat through several heat distribution lines substantially reduces energy losses in the gas treatment. This may also be facilitated by using the phase change of the working fluid in the heat distribution line to accept or transfer thermal energy.

Specifically, the method comprises the following steps: the present invention provides a process for the production of hydrocarbon compounds comprising the steps of: a) generating hydrogen gas from water in an electrolyzer using electrical energy; b) supplying at least a portion of the produced hydrogen and carbon dioxide externally provided from any source to a reverse water gas shift reactor to produce synthesis gas as a mixture of carbon monoxide and hydrogen with some residual carbon dioxide and water as a by-product; and c) feeding the withdrawn synthesis gas from the reverse water gas shift reactor to a Fischer-Tropsch reactor to produce a mixture of hydrocarbon compounds and a water by-product; is characterized in that: b1) the reverse water gas shift reactor comprises one or more reactors connected in series with intermediate steam separation; and transferring at least a portion of the excess thermal energy from the fischer-tropsch process to one of the other process steps in the process that require energy. The process according to the invention further comprises separating at least a portion of the carbon dioxide gas from the effluent stream of the at least one reverse water gas shift reactor and returning it to the inlet of the at least one reverse water gas shift reactor. The process according to the invention, wherein the operating temperature of the reverse water gas shift reactor is between 350 ℃ and 500 ℃. The process according to the invention, wherein the fischer-tropsch reactor comprises one or more serially connected fischer-tropsch reactors with at least intermediate steam separation. The process according to the invention wherein the fischer-tropsch reactors are operated at different temperatures. The method according to the invention further comprises the process of combusting one or more of said hydrocarbon compounds in a combustor-generator to produce at least a portion of said electrical energy. The process according to the invention, wherein at least a portion of the excess thermal energy from the fischer-tropsch process is transferred to the reverse water gas shift reactor using a heat pump. The process according to the invention, which also comprises varying the temperature of the gas in the process "adiabatically", which incorporates the range of ± 10% of the ideal adiabatic process; and/or "isothermally" varying the pressure of the gas in the process, which incorporates a range of ± 10% of the ideal isothermal process temperature. The method according to the invention further comprises a heat distribution process, wherein a heat distribution line is provided connecting two or more of said process steps, for receiving heat from said process steps or for supplying heat to said process steps to reduce the need for a surplus of such heat or thermal energy to be supplied externally. The method according to the invention, wherein at least some of the heat distribution lines are passed through one or more heat exchangers used in the process steps for the exchange of heat or thermal energy, wherein the working fluid in the heat distribution lines that transfers heat or thermal energy is in the gaseous state upstream of the heat exchangers and in the liquid state downstream of the heat exchangers. The present invention also provides a system for producing hydrocarbon compounds, comprising the following units: an electrolyzer that generates hydrogen from water using electrical energy; a reverse water gas shift reactor to which at least a portion of the produced hydrogen and carbon dioxide provided externally from any source are supplied to produce synthesis gas as a mixture of carbon monoxide and hydrogen with some residual carbon dioxide and water as a by-product; and a fischer-tropsch reactor to which is fed synthesis gas discharged from the reverse water gas shift reactor to produce a mixture of hydrocarbon compounds and a water by-product; is characterized in that: the reverse water gas shift reactor comprises one or more reactors connected in series with intermediate steam separation; and a line for transferring at least a portion of the excess thermal energy from the fischer-tropsch process to one of the other units in the system that require energy. The system according to the invention further comprises a unit for separating at least a portion of the carbon dioxide gas from the at least one reverse water gas shift reactor effluent stream and returning it to the at least one reactor inlet. The system according to the invention, wherein the operating temperature of the reverse water gas shift reactor is between 350 ℃ and 500 ℃. The system according to the present invention, wherein said fischer-tropsch reactor comprises one or more serially connected fischer-tropsch reactors with at least intermediate steam separation. The system according to the invention, wherein the fischer-tropsch reactors are operated at different temperatures. The system according to the invention further comprises a combustor generator for combusting one or more of said hydrocarbon compounds to produce at least a portion of said electrical energy. The system according to the invention further comprises a heat pump for transferring at least a portion of the excess thermal energy from the fischer-tropsch process to the reverse water gas shift reactor. The system according to the invention, which also comprises one or more units for "adiabatically" varying the temperature of the gas, incorporates a range of ± 10% of the ideal adiabatic process; and/or one or more units for "isothermally" varying the gas pressure, which incorporates a ± 10% range of the ideal isothermal process temperature. The system according to the invention further comprises a heat distribution line connecting two or more of said process units, said heat distribution line being adapted to receive heat from said process units or to supply heat to said process units to reduce the need for a surplus of such heat or thermal energy supplied externally. The system according to the invention, wherein power is supplied to the electrolyzer, said power supply comprising a rectifier connected to a multiphase power supply having three phases or more. The system according to the invention, wherein said rectifier is powered by a phase shifting transformer. The system according to the invention further comprises a nuclear power generating device for generating electrical energy. The present invention includes systems and methods that provide the ability to produce a variety of hydrocarbon compounds, such as compounds for different fuels, and to control the degree in the production of one or more specific types of hydrocarbon fuels, not found in currently available methods for producing synthetic fuels. These and other objects, features and advantages of the present invention will become more apparent from the following description when read in conjunction with the accompanying drawings.

Drawings

Fig. 1-4 depict an overall high-level system of the present invention according to a preferred embodiment.

Fig. 5-6 depict a preferred embodiment of the present invention in conjunction with the system of fig. 1-4.

Fig. 7 shows a different configuration of the energy distribution lines of the present invention.

FIG. 8 shows the operating principle of the RWGS reactor sub-assembly according to a preferred embodiment of the invention.

FIG. 9 depicts a three-stage RWGS reactor with carbon dioxide recycle according to a preferred embodiment of the invention.

FIG. 10 shows a RWGS reactor with a heater according to a preferred embodiment of the invention.

Figure 11 shows the principle of operation of an FT reactor sub-assembly according to a preferred embodiment of the invention.

Figure 12 shows a two-stage FT reactor according to a preferred embodiment of the present invention.

FIG. 13 depicts an FT reactor with a water cooler according to a preferred embodiment of the invention.

Figure 14 shows a portion of a hydrogen unit of an electrolyzer cell of the invention according to a preferred embodiment.

Figure 15 depicts an example of supplying power to the electrolyzer of the invention according to a preferred embodiment.

Fig. 16 depicts different winding arrangements of a phase-shifting transformer.

Figure 17 is a voltage diagram of an electrolyzer according to a preferred embodiment of the invention.

FIG. 18 illustrates a fuel aftertreatment system according to a preferred embodiment of the invention.

FIG. 19 depicts a combustion system according to a preferred embodiment of the present invention.

FIG. 20 depicts a flow diagram of an energy efficient electro-mechanical gas separation method.

Fig. 21 shows an adiabatic engine according to a preferred embodiment of the present invention.

FIG. 22 shows an isothermal gas mixture pressure transducer according to a preferred embodiment of the present invention.

Fig. 23 depicts a combined condenser and evaporator according to a preferred embodiment of the present invention.

FIG. 24 depicts an electrical energy distribution and recirculation line according to a preferred embodiment of the present invention.

Fig. 25-26 depict heat distribution and recirculation lines according to a preferred embodiment of the present invention.

Figure 27 shows a cooling loop for an FT reactor according to a preferred embodiment of the invention.

Figure 28 shows the steam/water feed to an electrolyzer according to a preferred embodiment of the invention.

FIG. 29 shows the primary loop control of the RWGS sub-assembly in accordance with a preferred embodiment of the present invention.

FIG. 30 shows the main loop control of the FT sub-assembly according to a preferred embodiment of the invention.

FIG. 31 shows hydrogen supply control of the RWGS sub-assembly in accordance with a preferred embodiment of the present invention.

FIG. 32 shows hydrogen supply control for the FT sub-assembly according to a preferred embodiment of the invention.

Detailed Description

The present invention includes systems, methods, and compositions for producing hydrocarbon compounds. Complete combustion of hydrocarbon fuels such as coal, natural gas, liquefied petroleum gas, ethanol, methanol, gasoline, kerosene, diesel, and other known fuels produces primarily two basic species-carbon dioxide and water. When burning such fuels, the main reactions are as follows:

C_nH_2n+2+(n+(2n+2)/2)*O₂energy of combustion → high calorific value +

n*CO₂+(2n+2)/2*H₂O (Water) (1)

For example, for an average value of n 10, 10% more water is produced than carbon dioxide. The total number of moles of oxygen used is equal to 1.55 moles, which is the sum of 1 mole for the oxidation of carbon and 0.5 mole for the oxidation of hydrogen plus 10%. As used herein, "high heating value" (HHV) refers to the amount of heat generated by the complete combustion of a unit amount of fuel when all of the combustion products are cooled to the temperature prior to combustion and the water vapor formed during combustion condenses.

In the invention described herein, the products of combustion-carbon oxides and hydrogen are recombined into hydrocarbon compounds, examples of which are transportation fuels, including but not limited to diesel and gasoline. It is also possible to recombine carbon oxides and hydrogen into other compounds and compositions, such as natural gas or liquefied petroleum gas. As used herein, hydrocarbon compounds include hydrocarbon compounds that can be used as energy sources, such as fuels.

The hydrocarbon compounds may be produced using a fischer-tropsch process. In this portion of the process and system, carbon monoxide (CO) and hydrogen are desirably reacted as follows:

CO+2H₂→(-CH₂-)+H₂O (2)

wherein (-CH)₂-) are building blocks for polymerization into longer carbon chains. The main product of this polymerization is a linear alkane C_nH_2nAdding two hydrogen atoms at the end gives any chain. In this reaction, 1 hydrogen molecule is used to form the hydrocarbon, plus about 10% hydrogen at the end to obtain the complete chain, and another hydrogen molecule is used to reduce carbon monoxide to carbon.

There are various methods for producing carbon monoxide from carbon dioxide. One such process is the chemical process known as the reverse water gas shift Reaction (RWGS). The reaction is as follows:

CO₂+H₂CO+H₂O (3)

in this reaction, molecular hydrogen is required to reduce carbon dioxide to carbon monoxide.

For the reactions given here, a ratio of 1.1+1+1 to 3.1 moles of hydrogen per 1 mole of carbon dioxide is used in order to produce hydrocarbon compounds. If water is used as the hydrogen source, the calculation can be done as follows:

externally supplied water 1.1 × H₂O+

Water H from RWGS reaction₂O+ (4)

Water H from the Fischer-Tropsch reaction₂O+

Electric energy for water electrolysis 3.1H₂+3.1/2*O₂

Ideally, the amount of oxygen released is the same as the amount of oxygen consumed by combustion, thereby completing the recirculation process. All or a portion of the water used in the methods and systems taught herein may also be an external source. Various methods can be used to produce hydrogen from water, for example, electrolysis of water can be used to produce hydrogen, photosynthesis can be used to produce hydrogen, or water can be heated to produce hydrogen. In preferred embodiments water electrolysis is selected, but other methods of generating hydrogen are known to those skilled in the art and are contemplated by the present invention.

One aspect of the present invention includes systems and methods, preferably including an electrolyzer, a reverse water gas shift reactor, and a fischer-tropsch reactor, for producing hydrocarbon compounds. The present invention includes methods and systems for producing hydrocarbon compounds, the methods and systems comprising the steps of: at least a portion of one of the carbon oxides (including but not limited to carbon monoxide) is converted via a fischer-tropsch process to one or more hydrocarbon compounds in the presence of at least a portion of the hydrogen stream, and at least a portion of the excess thermal energy from the fischer-tropsch process is transferred to one of the other process steps in the process that require energy, or to one of the other units in the system, such as an electrolyzer or a reverse water gas shift reactor.

An electrolyzer may be used to separate water into a hydrogen stream and an oxygen stream.

The process may further comprise converting carbon oxides, said carbon oxides comprising carbon dioxide. This step of converting the one or more oxides of carbon may comprise converting carbon dioxide in a Reverse Water Gas Shift (RWGS) process. CO 2₂The conversion of (a) is carried out in the presence of hydrogen and the hydrogen may be provided by at least a portion of the hydrogen from the hydrogen stream from the electrolyzer. The conversion of carbon dioxide to carbon monoxide may be achieved by any method known to those skilled in the art and such methods are contemplated by the present invention.

The carbon monoxide stream for use in the present invention may be provided from any source, for example, the source may be a carbon monoxide stream from a source separate from and external to the present invention. The second source of carbon monoxide is part of the effluent stream of an optional reaction process for converting carbon dioxide to, inter alia, carbon monoxide. The carbon dioxide stream for the process may be derived from, for example, a carbon dioxide off-gas from a source outside of the present invention.

The effluent of the fischer-tropsch process may be subjected to upgrading processes to upgrade the hydrocarbon series into desired hydrocarbon compositions, such as various liquid fuels. As used herein, "upgrading", "post-processing" and "refining" or "upgrading", "post-processing" and "refining" are used interchangeably and refer to the separation, isolation, purification, or in some way, such as fractional distillation, of the various hydrocarbon compounds provided by the synthesis reaction in the fischer-tropsch reactor by chemical or physical properties and the conversion of said compounds into products or feedstocks that can be used in other processes. Examples of conversion processes include, but are not limited to, oligomerization, hydrocracking, isomerization, aromatization, hydrogenation, hydroisomerization, and alkylation.

As used herein, "C" is₃Compound "refers to a compound having three carbon atoms. For example, propane is C₃A hydrocarbon compound.

As used herein, "C" is₄Compound "refers to a compound having four carbon atoms. For example, butane is C₄A hydrocarbon compound.

As used herein, "C" is₅₊The compound "means a compound having five or more carbon atoms. For example hexane, octane and compounds such as benzene as C₅₊A hydrocarbon compound.

In one embodiment of the invention, a system and method for producing hydrocarbon compounds from the products of fuel combustion (carbon oxides) is described and includes: providing an amount of electricity, such as electricity from a nuclear reactor, to a device that uses a portion of the electricity to form a hydrogen gas stream from water; and reacting at least a portion of the fuel combustion products, carbon dioxide, and carbon monoxide in the presence of at least a portion of the hydrogen from the hydrogen gas stream to form hydrocarbon compounds; wherein the use of electrical energy is minimized by recycling the energy consumed and released in the different processes.

In a preferred embodiment, when the process and system of the present invention uses carbon dioxide as a carbon oxide, the process and system converts the input electrical energy to a high heating value of the output hydrocarbon compound combustion energy ranging between 1.4 and 1.1, and when the process and system uses carbon monoxide as a carbon oxide, the process and system converts the input electrical energy to a high heating value of the output hydrocarbon compound combustion energy ranging between 0.64 and 0.84, or there is no conversion of carbon dioxide to carbon monoxide.

In one embodiment of the invention, carbon dioxide and/or carbon monoxide and water are converted into hydrocarbon compounds containing carbon and hydrogen using electricity, wherein hydrogen is supplied to the conversion process using a water electrolyzer. Carbon dioxide may be supplied externally to the process and converted to carbon monoxide for further use in the methods and systems of the present invention. Carbon monoxide may also be supplied to the process from outside, and mixtures of carbon oxides may also be supplied.

The system, method and apparatus of the present invention may include multiple subsystems, each of which contributes to the overall efficiency and productivity of the overall method, system or apparatus. For example, the invention may include a source of electrical energy, an electrolyzer, a RWGS reactor, an FT reactor, and a post-treatment device.

In one embodiment of the invention, there is a source of heat-producing electrical energy for a nuclear reactor. One example is a fast breeder reactor. Such reactors can be reset when they produce nuclear waste that requires reprocessing, and their nuclei can be subsequently reprocessed in a reprocessing apparatus. This has the following advantages: the energy output of worldwide uranium reserves is expanded to nearly 25 times. During a typical reprocessing interval of five years, a large quantity of initial fuel powers the present invention until the end of the useful life of the physical device. Alternatively, energy may be provided by nuclear reactor waste thermal conversion, thermochemical processes, or other sources, including non-fossil fuel power, such as hydrogen, sunlight, ocean waves, wind, tides, or gas streams, and any combination of these sources.

Electrical energy can be used to electrolyze water to produce hydrogen and oxygen. In certain embodiments, the electrolyzer requires a significant amount of heat to operate. This heat for operation, together with water, may be provided by steam generated elsewhere in the plant.

While hydrogen can be produced by conventional electrolysis of water using electrodes, other methods can be employed, including pyrolysis of water (e.g., using waste heat from a nuclear reactor), thermochemical methods, and combinations of these methods. The oxygen produced in the electrolyzer can be used outside the apparatus.

The method of electrolyzing water to produce hydrogen preferably comprises an electrolyzerIncluding bipolar electrodes and cells having an average operating temperature in excess of 100 c or in excess of 130 c, wherein the cell pressure is in excess of 10bar or in excess of 20 bar. Other embodiments include more than 3,000A/m²Current density, battery packs having voltages in excess of 60V and/or the use of AC to DC voltage rectifiers to cause output voltage fluctuations below 3%.

Hydrogen produced within the electrolyzer has many uses in the apparatus. Among other things, hydrogen and carbon dioxide can be used together in a RWGS reactor to produce a mixture of carbon monoxide and hydrogen, i.e., syngas.

The source of carbon dioxide for use in the process of the invention is a plant which emits carbon oxides such as carbon dioxide or carbon monoxide as by-products, particularly a plant which requires reduced emission of carbon oxides. Examples of such plants include blast furnaces used to produce steel and fossil fuel power plants that use coal or gas to generate electricity. Carbon dioxide, carbon monoxide or carbon oxides or mixtures thereof may be provided by any method, including but not limited to externally provided from any source.

One method of converting carbon dioxide to carbon monoxide is through the use of RWGS reactors. One aspect of the invention includes methods and systems in which carbon dioxide and hydrogen are supplied to a RWGS reactor and carbon dioxide is substantially completely converted to carbon monoxide, e.g., at a conversion of more than 70%, more preferably more than 80%, even more preferably more than 90%. The output or effluent gas stream of the RWGS reactor comprises H₂Carbon monoxide and hydrogen in a/CO ratio between 0 and 3. Further, means are included for separating a portion of the carbon dioxide at the output location and recycling the carbon dioxide to the input location. Other preferred embodiments may include: operating temperatures between 350 ℃ and 500 ℃ provide vapor separation by condensation and more than one reactor may be connected in series in sequence. Embodiments may include intermediate separation of steam between RWGS reactors connected in series.

Water formed as a byproduct of RWGS reactor operation may be fed to the electrolyzer.

The effluent syngas, typically a mixture of carbon monoxide and hydrogen with some residual carbon dioxide, is fed from the RWGS reactor to the FT reactor. Additional hydrogen may be added to the syngas, or to the carbon monoxide, depending on the desired output requirements of the FT reactor. It is also possible to use carbon monoxide, such as carbon monoxide off-gas from an existing industrial process, and combine this carbon monoxide with hydrogen instead of or in addition to the syngas stream produced by the RWGS reactor. The apparatus of aspects of the invention includes a process that uses carbon monoxide without the need for an intermediate step of converting carbon dioxide to carbon monoxide, thereby eliminating the RWGS process.

The FT unit of the invention may comprise more than one FT reactor which converts carbon monoxide and hydrogen to hydrocarbon compounds predominantly in the desired ratio, for example, a conversion of more than 70%, more preferably more than 80%, even more preferably more than 90%. In the present invention, these methods and systems provide for the removal of the heat of reaction under substantially isothermal conditions. In addition, the supply of hydrogen is controlled to minimize the production of methane and ethane. Other embodiments include providing for separation of exported steam and gaseous hydrocarbons using condensation caused by both temperature and pressure changes, and including connecting more than one FT reactor in sequence or series, or having more than one reactor operating at substantially different temperatures and associated operating conditions.

The catalyst for the FT reaction may be: metals such as iron, cobalt, nickel, and combinations thereof; metal oxides such as iron oxide, cobalt oxide, nickel oxide, ruthenium oxide, and combinations thereof; supported materials such as alumina or zeolites; supported metals, mixed metals, metal oxides, mixed metal oxides; and combinations of these catalysts, as well as other catalysts known to those skilled in the art.

The main output of the FT reactor is a mixture of hydrocarbon compounds and a water byproduct, which may have a variety of uses, such as being feedable to an electrolyzer. The FT reactor is largely exothermic and the heat can be used in a number of ways. For example, at least a portion of the heat may be removed by converting a stream of water to steam, which may then be fed to the electrolyzer if desired.

The mixture of hydrocarbon compounds exiting the FT reactor may be fed to a post-treatment unit which may be similar to, or in many respects simpler than, existing hydrocarbon fuel refining plants because it is not necessary to remove sulfur or nitrogen compounds. An amount of hydrogen compound may be used in such post-treatment refining processes to obtain a composition containing combustible compounds. Such compositions may be used as fuels.

When post-treated, the desired transportation grade fuel composition is provided, which may include high octane gasoline and diesel fuels of a composition that reduces or even eliminates the need for post-treatment by the vehicle. The fuel compositions produced by the present process overcome the inherent disadvantages of crude oil processing, namely, the absence of sulfur content, the absence of nitrogen content, and the absence of aromatic content of these compositions. However, these compositions have high capacity and high weight energy density, excellent resistance to thermal oxidation processes, fire resistance (i.e., these compositions are difficult to ignite), and excellent low temperature performance.

The present system also provides a novel and inventive combination of a heat exchanger and a compressor/expander for separating gases in a gas mixture using a separator. The system may include the use of a compressor or expander to condition the gas mixture for condensation of a selected gas in the mixture by heating or cooling, wherein the expander and compressor are used to condition the gas mixture to a desired temperature. The system may use a heat exchanger to condense or vaporize a selected gas, with the cooling fluid appropriately phase-changed to a vapor or steam of the fluid. Other embodiments include phase change and gas compression or expansion of the working fluid for heating or cooling. A heat engine, for example a heat pump using a compressor, may be used to transfer heat from the low temperature region to the high temperature region, and a heat remover with an expander generator (power generation) may be utilized.

The present invention provides an energy efficient system for converting carbon oxides, including carbon dioxide and carbon monoxide, with water on a production scale into hydrocarbon fuels using energy, for example using electrical energy. The system of the present invention further comprises utilizing the internally retained heat for power generation, wherein the generated power is used to convert carbon dioxide, carbon monoxide and water into hydrocarbon fuels. The system may also include a compressor and an expander for conditioning and separating the components of the gas mixture.

The invention further introduces one or more subsystems whose functions include: transferring heat or steam between components of the system, transferring heat from the FT reactor to the electrolyzer directly or by conversion to electrical energy, feeding reaction steam from the FT reactor for condensation in the electrolyzer, transferring heat from the FT reactor for the entire system by using heat and via using heat exchange methods, and together with associated input/output gas treatment transferring heat from the FT reactor to the RWGS reactor, heating reaction water from the RWGS reactor and/or the FT reactor for use in the electrolyzer, and feeding heat to gas-liquid phase conversion for cooling and heating process gases and liquids.

The invention also includes the use of a gas expander with a generator and a gas compressor with a motor for receiving and supplying electrical energy, i.e. for recirculation, thereby significantly reducing the total energy used in the plant.

The invention as shown in fig. 1 actually includes the process 100 of the invention, the process 100 of the invention being a process for converting one or more oxides of carbon into a hydrocarbon fuel F using electricity as the energy input E. The output fuel F may include, for example, gasoline, diesel fuel, and jet fuel. Fig. 1-4 depict an overall high-level system 100 of the present invention which embodies its own novelty and inventive step, respectively, as described below, and together form a preferred method 100 of the present invention as shown in fig. 5 and 6.

While the production of hydrocarbon fuels from coal and gas is known, the use of electricity to drive the conversion has been avoided in the past. The development of processes for producing fuels from carbon oxides using electricity has been controlled by the industry because energy efficiencies are simply too low to justify cost effectiveness. However, the energy efficiency of the invention is higher than 60%, in other words the ratio of the high heating value of the fuel F to the amount of electricity E required to drive the conversion is greater than 60%, and more preferably greater than 80%. In inverse proportion, the amount of electrical energy is less than about 1.7 (1/60%) times the high heating value of fuel F, and more preferably less than 1.25 times.

As shown in fig. 2, in a further advanced system 100 of the present invention, the method of the present invention comprises an energy input step 200 to provide energy to the method, a conversion step 300 to convert one or more oxides of carbon to fuel F, and a hydrogen input step 400 to provide hydrogen to efficiently drive the conversion of the oxides of carbon to fuel F300.

Referring to the step 300 of converting carbon oxides to fuel F, as shown in fig. 3, it may comprise at least two subsystems, one being a carbon monoxide conversion step 320 for converting carbon monoxide to fuel F, and the other, carbon dioxide conversion step 360, should be the process 100 of the present invention providing carbon dioxide thereto. The conversion step 360 converts carbon dioxide to carbon monoxide and then feeds the carbon monoxide to the carbon monoxide conversion step 320. Alternatively, or in combination with the carbon monoxide from the reforming step 360, carbon monoxide outside the inventive system 100 may be fed to the reforming step 320, e.g., a carbon monoxide off-gas stream or CO from a plant may be fed₂And CO to step 360, thereby introducing CO₂Is converted into CO.

Both reforming steps 320, 360 utilize at least a portion of the hydrogen from the hydrogen input step 400 to drive the reforming of each of the two reforming steps. In a preferred embodiment, carbon dioxide and carbon monoxide are provided to the present invention 100, and thus the present method 100 utilizes two conversion steps 320, 360.

In fig. 4, an intermediate step 500 is shown interposed between the output of the conversion step 300 of carbon oxides and the final product fuel F. Typically, the output of the conversion step 300 is a series of hydrocarbon compounds HC, only some of which are available for fuel. Thus, a post-treatment step 500 is provided to upgrade them into a desired composition, such as fuel F.

Fig. 5 and 6 show a preferred embodiment of the different subsystems of the present invention 100 and include a recycling process and apparatus to form hydrocarbon fuel from the combustion products of the hydrocarbon fuel. The present invention includes an energy input step 200 to provide energy to the process, including the use of a nuclear power reactor 210 to generate electricity, preferably a fast breeder reactor that consumes existing nuclear waste. The nuclear waste that needs reprocessing once the reactor 210 produces it should be set immediately and its nuclei can then be reprocessed in, for example, a reprocessing device 220 to expand the energy output from worldwide uranium reserves by a factor of about 25 or more. As will be appreciated by those skilled in the art, during a typical reprocessing interval of five years, there is sufficient initial fuel to power the present invention until the end of its useful life.

Power is supplied to the hydrogen input step 400, and the hydrogen input step 400 may include electrolyzing water in an electrolyzer 410 to form a hydrogen gas stream and an oxygen gas stream. Heat (also referred to as thermal energy) from other subsystems of the method of the present invention 100 may be supplied to this step to improve efficiency. The thermal energy can be used directly to heat water when needed or to perform electrolysis by conversion to electricity. Some known types of electrolyzers 410 may require some heat to operate. This heat, along with the water used for the electrolysis operation, is preferably supplied primarily by steam generated elsewhere in the system of the invention 100. Although it is preferred that most, if not all, of the oxygen formed be put to revenue-producing uses outside of the inventive system 100, the hydrogen formed in the electrolyzer 410 has many uses throughout the system.

At least a portion of the hydrogen is fed to the reforming step 300, which is a two-step process if the system 100 of the present invention processes carbon monoxide and carbon dioxide simultaneously. In a first process, a carbon dioxide shift step 360 is employed to combine hydrogen and carbon dioxide to produce a synthesis gas, which is a mixture of carbon monoxide and hydrogen, wherein the shift step 360 includes a reverse water gas shift process, namely a Reverse Water Gas Shift (RWGS) reactor 362. Steam fed to electrolyzer 410 is formed as a byproduct of the RWGS reactor operation.

The source of carbon dioxide for the conversion step 360 can be a device that emits carbon dioxide as a byproduct, particularly a device that needs to reduce carbon dioxide emissions. The main examples of such plants are blast furnaces for producing steel and fossil fuel power plants that generate electricity using coal or gas.

The carbon dioxide may be mixed with carbon monoxide. This mixture may be separated into carbon dioxide and carbon monoxide or treated as a mixture in a reactor 362 that effects the conversion of carbon dioxide to carbon monoxide.

The syngas is then fed to a carbon monoxide conversion step 320, comprising a fischer-tropsch process that combines carbon monoxide with hydrogen to provide a range of hydrocarbons based on double bond radicals. The carbon monoxide conversion step 320 may include a fischer-tropsch (FT) reactor 322. While FT reactor 322 may use syngas from step 360, it is also possible to use carbon monoxide off-gas from an existing industrial process and combine this carbon monoxide off-gas with hydrogen instead of or in addition to syngas generated by RWGS reactor 362. As is known, there are numerous processes that produce carbon monoxide off-gas, particularly processes that produce an off-gas of a combination of carbon monoxide and carbon dioxide.

In a preferred embodiment of the present system 100 of the present invention, only carbon monoxide is treated (and no carbon dioxide is treated) because such a system substantially eliminates the need for the RWGS process 360. The system 100 of the present invention may also use a mixture of carbon dioxide and carbon monoxide as an off-gas from an industrial process that provides the mixture. Additional hydrogen may be added to the syngas output of step 360 and/or to the carbon monoxide input of step 320 as needed to adjust the output of FT reactor 322 to a desired value.

The primary output of FT reactor 322 is based on- (CH)₂) A mixture of hydrocarbon compounds of radicals, and the by-product is water, which is preferably fed to the electrolyzer 410. The FT reaction is largely exothermic and this heat is removed at least by converting water to steam, which can be used as an energy source directly or indirectly to electrolyzer 410.

The hydrocarbon compounds output by the FT reactor may be characterized as crude oil versions as hydrocarbon compounds, such as crude oil, from which fuel compounds may be obtained using known techniques. Thus, the hydrocarbons may be upgraded or refined at step 500, including a fuel post-treatment step, to produce a desired composition of fuel F. Step 500 may include a post-treatment (upgrading) unit 510, the post-treatment (upgrading) unit 510 being similar to existing crude oil refining plants, but generally simpler, with fewer treatment steps required. Such refining techniques are known to those skilled in the art. In addition, an amount of hydrogen from step 400 may be used in such a refining process 500.

The present invention utilizes multiple energy distribution lines, an air flow recirculation/feedback loop, and intermediate process heat and electricity exchanges. The overall result of the various improvements in efficiency in each subsystem of the invention 100 and across the system provides a system in which the energy input to the process (e.g., from the electricity produced by the nuclear power plant) is preferably at least 60% ultimately contained in the high heating value of the combustion output fuel F.

Where the output of the system 100 of the present invention is fuel and oxygen, it produces beneficial byproducts simultaneously. Furthermore, the system of the present invention 100 provides a key external economic benefit since it reduces carbon dioxide. Carbon dioxide is a greenhouse gas that has been the subject of various global treaties, such as the kyoto protocol and national and regional enforcement regulations, because it is the leading cause of global warming.

As described, the final output of this recycling process of the present invention 100 is a variety of desired transportation fuels, which may include sulfur-free high octane gasoline and sulfur-free diesel fuel that have a composition that reduces or even eliminates the need for vehicle aftertreatment. One advantage of the system of the present invention 100 is the ability of the system to produce a variety of hydrocarbon compound fuels. Another advantage is the ability to control the ratio of hydrocarbon compounds formed for plant operators by adjusting certain parameters of the process and system, for example, the ratio of carbon monoxide to hydrogen fed to a particular FT reactor. By varying the amount of synthesis gas fed to different types of FT reactors, it is possible to obtain different output ratios of diesel, gasoline, jet fuel and other fuels from the total synthesis gas input.

The system 100 of the present invention, including preferred embodiments of the various subsystems of the present invention, is described in greater detail below.

Energy distribution line

The system of the present invention 100 incorporates several energy distribution lines with two particular types of energy lines-electricity and heat. Fig. 7 shows an embodiment of the energy distribution lines employed in the present system. At least one Electrical Distribution Line (EDL) is used. For example, one type of EDL is a conventional three-phase alternating current power distribution line operating at a conventional phase-to-phase voltage in the 10-50kV range (a range in which commonly used power generators are implemented). However, it will be generally understood by those skilled in the art that other voltages may be used depending on the particular needs.

In such a system, multiple generators and motors are connected to the EDL. The generators are preferably synchronous, with the generators being conventionally controlled to match frequency, phase and voltage amplitude, so that the generators can all transmit power in parallel to the EDL. This type of control is used for existing power grid control. To achieve higher efficiency, the motor is preferably of a controlled synchronous type, but other types of motors may be used.

In the preferred system of the present invention 100, additional energy distribution lines, heat or thermal energy (as opposed to electrical energy) are distributed throughout the device. A Heat Distribution Line (HDL) in such a system can receive heat from a heat source and deliver the heat to a heat user.

Phase change of the working fluid is used in the heat distribution lines. Two reservoirs are used for each line-one being a liquid reservoir and the other being a vapor reservoir of such liquid, both reservoirs having a temperature and pressure close to the boiling temperature and pressure of the working fluid. When heat transfer is required, steam is withdrawn from one half of the line, condensed and delivered to the other half of the liquid line. The condensation heat is released to the hot user. When heat recovery is required, the liquid is then recovered, evaporated and delivered as a vapor to the other half of the vapor line. The external heat is consumed by evaporation of the working fluid.

In the preferred embodiment, five different temperatures are used for each of the five heat distribution lines.

The first HDL is preferably at the operating temperature of RWGS reactor 362, preferably in the range of 280-. In a preferred embodiment, the RWGS reactor 362 is operated at a temperature of about 400 ℃. At this temperature, it is preferred to use ethylene glycol as the working fluid or to use another fluid with a similar heat of vaporization and a similar boiling pressure at 400 ℃. This first HDL is used to heat at least the gas introduced into the RWGS reactor and, when the RWGS reaction is endothermic, to deliver heat to the RWGS reactor itself. In further description herein, this first HDL is sometimes referred to as the "RWGS-line" and has its vapor portion designated as "V" and liquid portion designated as "L".

The second HDL is preferably at the operating temperature of FT reactor 322, preferably in the range of 180 ℃. When used in coal-fired and nuclear power plants, the second HDL working fluid is preferably water. It is also possible to use a separate cooling loop for the FT reactor operating at higher temperatures using other working fluids such as ethylene glycol and to exchange some or all of its heat to this second HDL. In further description herein, this third HDL is sometimes referred to as the "FT-line" and its vapor portion is designated as "S" and water portion as "W".

The third HDL is at the temperature of the water in electrolyzer 410. For example, it may be in the range of 100-150 ℃, preferably in the range of 130-140 ℃. The primary purpose of the third HDL is to supply water and/or steam to electrolyzer 410. The third HDL preferably uses water as the working fluid. In further description herein, this third HDL is sometimes referred to as the "E line" and its vapor portion is designated as "S" and water portion as "W".

The fourth HDL is at room temperature, 25 ℃ in the case of one preferred embodiment of the system, but can be other room temperatures at different locations and climatic conditions of the system. The working fluid may be a refrigerant that is commonly used at this room temperature. The primary use of the fourth HDL is to process the incoming and outgoing materials. In further description herein, this fourth HDL is sometimes referred to as the "a-line" and has its vapor portion designated as "V" and its liquid portion designated as "L".

The fifth HDL is preferably at the operating temperature of carbon dioxide separator 372 of fig. 8, preferably in the range of-50 to-55 ℃. At such temperatures, it is preferred to use a conventional refrigerant, such as ethylene. This fifth HDL is used to heat and cool the gases flowing into and out of the carbon dioxide separator. In the further description herein, this line is sometimes referred to as the "C line" and its vapor portion is designated as "V" and its liquid portion is designated as "L".

An additional source of available thermal energy is the waste heat of nuclear power plants that can be used by conversion to electrical energy.

Balancing of energy distribution lines

The energy distribution lines should be balanced so that the incoming energy is equal to the outgoing energy. The distribution line delivers electrical energy for electrolysis and a plurality of motors driving the compressor and feed pumps. The distribution line receives electrical energy from a plurality of gas expanders that drive the electrical power generator, the gas expanders comprising expanders that convert thermal energy released by the FT reactor or convert thermal energy released by burning residual gases. The remaining amount of power is delivered by the external power source 210.

The RWGS-line is balanced in a preferred manner by energy delivered by the FT reactor through a heat pump. Within the overall system of the present invention 100, heat energy from such a pipeline is used to convert its vapor to a liquid.

In a preferred embodiment, the FT lines are balanced by heat from the FT reactor cooling.

In a preferred embodiment, the E line is balanced by heat from the FT reactor cooling.

In a preferred embodiment, the a-line is balanced by transferring energy to the environment. This line collects excess heat energy that the process cannot consume or convert to electricity. The main use is space heating by converting the vapor of the a-line to a liquid, especially in cold weather. If this heat is not needed, it can be dissipated to the environment using, for example, conventional heat exchangers.

For an economical construction there should be a typical temperature difference between the temperature of the environment, i.e. air or water, and the temperature of the pipeline. The operating (boiling) temperature of the line can be varied by adjusting the pressure.

In a preferred embodiment, excess heat is removed by a heat pump and transferred to the a-line to balance the C-line.

Energy input

The energy input step 200 preferably includes a power generation device 210 that uses the heat generated by the nuclear process. While various types of nuclear processes can be used, the apparatus requires periodic supply of nuclear fuel if a fast breeder reactor is not employed.

The system of the present invention 100 does not require the use of the raw or waste heat of the nuclear reactor, as other sources of energy can be used to generate electricity. For example, the system efficiency and output requirements of the present invention 100 may not only be met by nuclear energy, but also by, for example, hydroelectric or wind generators, as waste heat from an external energy source is not required at this time. Although fossil fuel power plants are not optimal, they may also be used.

Carbon oxide conversion

Carbon dioxide conversion

Carbon dioxide conversion is preferably performed by the RWGS process 360. As shown in fig. 8, a preferred carbon dioxide conversion system includes a RWGS reactor 362 that converts incoming carbon dioxide to carbon monoxide using hydrogen as a reductant.

The basic reaction is as follows:

CO₂+H₂CO+H₂O (5)

the reaction is reversible and has a low equilibrium coefficient for the conversion of carbon dioxide to carbon monoxide. For this reason, in a preferred embodiment of the present invention, an excess of the introduced gases carbon dioxide and hydrogen is used to increase the amount of carbon monoxide.

The amount of hydrogen is sufficient for: (i) conversion to water inside the reactor and (ii) H₂the/CO mixture (syngas) reaches the desired concentration to feed FT reactor 322. In this embodiment, the H₂the/CO ratio is about 2, so that the molar amount of hydrogen is up to about 3 times the molar amount of carbon dioxide fed in. Depending on the FT catalyst used, it may also be acceptable to feed to the FT reactorOther H₂The value of/CO.

At the selected operating temperature of the reactor 362, the amount of carbon dioxide at the inlet of the reactor 362 is preferably sufficient to achieve complete conversion of the introduced carbon dioxide. For example, in one embodiment, the RWGS process 360 has an operating temperature of 400 ℃ and is a three-stage RWGS reactor with intermediate steam separation. In such a design, the amount of carbon dioxide required at the reactor inlet is almost the same as the amount of carbon dioxide introduced, which is normally obtained, provided that H is present at the outlet₂the/CO ratio is close to 2. Thus, additional amounts of carbon dioxide are provided through the recirculation loop of the reactor assembly as shown in fig. 8. This additional supply of carbon dioxide is not consumed in the reactor but is recycled through the reactor to change the equilibrium conditions so that the introduced carbon dioxide is as close to complete conversion as possible. The two carbon dioxide streams (fresh and recycled) can be mixed in a conventional gas mixer 366 or fed to the RWGS reactor using separate suitably designed nozzles or distributors.

The amount of carbon dioxide in the recycle loop depends on the amount of hydrogen feed, the operating temperature of the RWGS reaction, and the number of reactors connected in series with steam separation between the reactors. With a lower hydrogen feed or a lower temperature or a lower number of reactors in series, there is a significantly greater amount of carbon dioxide in the recycle loop and vice versa. One advantage of having a small amount of gas in the recycle loop is that less electricity and heat loss is required to maintain the gas circulation and separation.

The output stream of the RWGS reactor 362 first passes through a steam condensing section 368 and then a carbon dioxide separator 372. In one embodiment, the vapor condensing section may comprise a condenser (heat exchanger) followed by a knock out drum. Condensed water from separator 368 may be re-fed to the electrolyzer. The separated carbon dioxide is delivered to an inlet of a gas mixer 366. The carbon dioxide separator 372 outputs directly the syngas and residual carbon dioxide (if any), wherein the syngas has H₂Ratio of/COAs may be advantageously required for effective conversion by FT reactor 322.

Other well known methods of converting carbon dioxide to carbon monoxide may be used in the present invention without altering the functionality of such equipment.

The operating pressure of the reactor may be in the range of from 4 to 30bar, preferably from 20 to 25 bar. GHSV-STP (gas hourly space velocity at standard temperature and pressure) is 1,500-15,000, preferably 5,000-8,000.

The steam is preferably separated at or near room temperature, where a high separation ratio is obtained.

The separation of carbon dioxide at the outlet can be achieved by conventional and current methods. Among other methods, the methods currently in common use include the following: amine absorption processes as well as carbonate processes, pressure swing absorption, adsorption and gas permeation. Furthermore, cryogenic separation is made possible by lowering the temperature and raising the pressure under suitable process conditions, such as-50 to-55 ℃ and 50-100bar pressure, so that only 15-35% mol/mol carbon dioxide compared to carbon monoxide may remain in the synthesis gas.

More likely, a low temperature solvent mediated process such as Ryan-Holmes or a three phase process such as CFZ (controlled freezing zone) can be used to further reduce the carbon dioxide content. The residual carbon dioxide will be recycled through upstream processing or may still be better consumed in the FT sub-assembly under certain operating conditions and then returned more or less to the inlet of that sub-assembly. Furthermore, some of these processes may be used in sequence, for example using cryogenic liquefaction to separate large amounts of carbon dioxide, followed by CFZ or amine absorption to condition the syngas to obtain the desired carbon dioxide concentration, i.e. a concentration of 3-10% in mol/mol compared to carbon monoxide. The water vapor must be completely removed before the cryogenic type separator. An adsorption type dryer may be used as is commonly practiced in the low temperature process.

FIG. 9 shows another preferred carbon dioxide conversion system and the conversion system includes a three stage RWGS. As shown, there are three steam separator sections, one after each reactor, and a carbon dioxide separator at the end of the process.

The RWGS reaction is weak in the direction of carbon monoxide formation and therefore requires removal of at least one reactant.

To achieve as close to 100% conversion as possible, the system of the present invention 100 can use a three-stage RWGS reaction, combined with the following steps: (i) removing steam at the outlet of each stage and (ii) increasing the molar concentration at the inlet.

First, the molar concentration of hydrogen is increased to the point where the resulting syngas will have up to the correct H for use in the upstream Fischer-Tropsch reactor 322₂Degree of the/CO ratio. In one embodiment, the ratio is 2 or higher.

To satisfy the RWGS reaction, in this embodiment, the first RWGS reactor 382 is fed with a molar ratio of 3: 1 compared to the molar content of carbon dioxide at inlet 384. 1 mole is used to reduce carbon dioxide to carbon monoxide and 2 moles remain in the exiting syngas.

Second, the inlet carbon dioxide to the first RWGS reactor 382 is added by forming a recycle line 386 from the outlet and recycling without conversion. It is desirable to add more than about 1 mole of carbon dioxide to the recycle loop to achieve about 100% conversion of 1 mole of inlet carbon dioxide in three RWGS reactors 382, 388, 394 in series, wherein the RWGS reactors have the configuration shown in figure 9.

The carbon dioxide conversion system of fig. 9 relies on steam removal and carbon dioxide separation. The first steam separator 392 removes steam from the effluent gas from the first RWGS reactor 382 and by this operation creates conditions for continued conversion of carbon dioxide in the second RWGS reactor 388. When carbon monoxide has not been removed, the conversion in the second reactor 388 is lower than in the first reactor 382.

The second steam separator 392 removes steam from the effluent gas from the second RWGS reactor 388 and by this operation creates conditions for continued conversion of carbon dioxide in the third RWGS reactor 394. When carbon monoxide has not been removed, the conversion in the third reactor 394 is lower than in the second reactor 388.

A third steam separator 392 is disposed at the outlet of the third RWGS reactor 394. At the outlet of the separator, the exit gas comprises a gas having the desired CO/H₂Syngas and carbon dioxide. Thus, carbon dioxide is separated using separator 396 and the separated carbon dioxide is placed into recycle line 386 to be combined with the incoming carbon dioxide 384 in gas mixer 398.

Additional hydrogen from electrolyzer 410 is then added if the syngas contains less hydrogen than has to be fed upstream to the FT reactor.

RWGS reactor

The RWGS reactor used in the present system of the present invention 100 can operate effectively at a large number of operating temperatures, but in a preferred embodiment 400 ℃ is used. An exemplary catalyst is KATALCO 71-5, produced by Johnson Matthey. The operating pressure may be in the range of 4-30bar, preferably higher pressure values are used in order to reduce the overall size of the assembly. The GHSV-STP used is 1,500-15,000, preferably 5,000-8,000.

The reaction is endothermic and requires external heat. In a preferred embodiment, the system of the present invention 100 utilizes isothermal operation (within 10% of the ideal operating temperature measured in ° K) in which external heat from an external source is transferred to the reaction zone. Fig. 10 depicts one example of an overall heat delivery system 810. In particular in RWGS lines, the phase change of the working fluid is used to transfer heat in an isothermal or near isothermal state. The vapor of the RWGS-line is delivered to the condensing coil 812. The vapor condenses and releases the heat of condensation, but maintains the temperature of the phase change. The remaining working fluid is released into the liquid portion of the RWGS-line. The released heat is consumed through a heat exchange process by reacting the gas inside the reactor.

Preferably, reactors 382, 388, 394 of fig. 9 are all of the same general construction, although the second and third reactors may be smaller than the first reactor because they need only convert a smaller amount of carbon dioxide to carbon monoxide and handle a smaller volume of gas mixture.

This RWGS sub-assembly can handle not only pure carbon dioxide but also mixtures of carbon dioxide and carbon monoxide. The mixture can be processed through one, two or all three reactors connected in series as a function of the ratio of carbon monoxide to carbon dioxide. In the case of pure carbon dioxide conversion, if this ratio is lower than the ratio at the outlet of the first reactor, then all three reactors will be used subsequently. Except that a reduced amount of carbon dioxide requires a reduced amount of hydrogen. The same rule will be used to determine whether two or only one reactor is needed to process this mixture. Finally, if only carbon monoxide is supplied, no reactor is required.

Alternative-carbon dioxide conversion

As discussed, the conversion of carbon dioxide is preferably run through the RWGS process 360. There are variations to this RWGS process that do not significantly alter the outcome, i.e., the production of the carbon monoxide component in the syngas.

For example, the reaction temperature in the reactor may be reduced. This decrease in temperature will decrease the equilibrium constant and thereby cause an increase in the amount of carbon dioxide in the recycle line or an increase in the number of reactors connected in series, or both.

Furthermore, the reaction temperature can be increased and it is possible to reduce the number of reactors in a preferred embodiment from 3 to 2 or to only 1 remaining, with the amount of carbon dioxide recycled being sufficient to bring the carbon dioxide introduced to 100% conversion.

It is also possible to reduce the amount of hydrogen fed to the process so that the carbon dioxide in the recycle loop is subsequently increased. It is also possible to reduce the amount of carbon dioxide circulation by using more than 3 reactors in series at the same temperature.

The heat of reaction need not be transferred isothermally but may be provided by heat exchange with any hot side fluid having a suitable temperature, flow rate, among other parameters.

Other methods of converting carbon dioxide to carbon monoxide are known and may be used in the present system of the present invention 100.

Carbon monoxide conversion

The conversion of carbon monoxide is preferably run by FT reactor processing 320. Figure 11 shows a reactor assembly. FT reactor 322 operates as follows:

CO+2H₂→(-CH₂-)+H₂O (6)

in (-CH)₂The dotted line at-) indicates a bond that can be used for hydrogenation or for polymerization. Many linear and oxygenated hydrocarbon compounds are produced in fischer-tropsch reactors as a function of the type of catalyst used in the reactor and the operating temperature, pressure and gas velocity.

In a preferred embodiment, as an example, the reactor is operated at 220 ℃ using a cobalt catalyst and produces a hydrocarbon mixture that after upgrading results primarily in a mixture of gasoline and diesel in a ratio of about 1: 2.

In other implementations of the invention, more gasoline is produced at higher temperatures, such as about 330-350 deg.C, where the ratio of gasoline to diesel is about 4: 1. Thus, by operating in combination at different temperatures, one skilled in the art can adjust the ratio of gasoline to diesel from 1: 2 to 4: 1. The production rate of diesel oil obtained by the present invention includes adjusting the temperature, pressure and residence time (gas flow rate). The amount of residual hydrocarbons that are difficult to convert to the desired liquid fuel varies, typically being higher at higher temperatures and lower at lower temperatures.

In one embodiment, a cobalt catalyst is used, wherein H₂The ratio/CO was 2.15, the operating temperature was 220 ℃, the pressure was about 20bar and the GHSV-STP was 1,500. The conversion of carbon monoxide to hydrocarbons is as high as 75%. The pressure may vary in the range of 10-30bar and the GHSV is 500-5,000.

The FT reactor 322 of fig. 11 produces liquid hydrocarbons that are discharged for further processing and gaseous hydrocarbons that are mixed with steam and input gases (carbon monoxide and hydrogen). The presence of the input gas is due to incomplete conversion of the synthesis gas. To obtain more complete conversion, more than one FT reactor may be used connected in series to remove steam and some hydrocarbon gases between the reactors. In a preferred embodiment example, a two-stage FT reactor is used to achieve higher conversion efficiency.

At the outlet of the reactor 322, steam is separated from the exit gas using a steam separator 324, and then carbon number C is separated via a separator 326₅-C₆And finally carbon number C via separator 328₃-C₄Is used as the gaseous hydrocarbon of (1). These separation processes may be combined as a function of the composition of the gas mixture before separation. The residual gas mainly comprises natural gas compounds and methane CH₄Ethane C₂H₆And residual carbon monoxide and hydrogen, and varying amounts of unseparated carbon dioxide and C₃And C₄A compound is provided.

In a preferred embodiment, a substantial portion of the syngas is returned to the inlet of FT reactor 322 via a recycle line, thereby increasing the conversion efficiency of the incoming syngas to hydrocarbon fuel. This conversion efficiency improvement may be achieved in part by using a controllable throttle or valve 332. Such a throttle valve is provided in the recirculation line for the exhaust gases and a portion of such exhaust gases is discharged or combusted in the same molar ratio. In a preferred embodiment, the control parameter is the amount of natural gas compounds before venting. The throttle valve is opened just enough to keep the amount at a predetermined level. Other gases may be used for the same purpose.

A gas conditioner 334 may be provided in the recycle line to match the temperature and pressure of the syngas from the RWGS assembly 360. The syngas is combined in gas mixer 336 or similarly in gas mixer 384.

Syngas may be replaced by feeding an external source of carbon monoxide off-gas (from outside the system of the invention 100) and hydrogen from the electrolyzer 410 or a mixture of these gases and syngas to the FT reactor 322. Hydrogen is added to the input from electrolyzer 410 to supply the required H for FT reactor 322₂the/CO ratio is adjusted. In a preferred embodiment, the H₂the/CO ratio is about 2 and more particularly between 2 and 2.2.

The gas exiting such a plant may be fed to a combustor-generator to generate electricity.

This FT module can be replaced by a number of conventional fischer-tropsch reactor units without altering the function of the plant. Figure 12 shows a more detailed preferred carbon monoxide conversion system. Depicted is a two-stage FT reactor system 340. There are two FT reactors 342, 344 in this assembly. Syngas from the RWGS sub-assembly and an amount of hydrogen from the electrolyzer are fed to first FT reactor 342. A quantity of liquid hydrocarbons is formed and discharged from the reactor. Unconverted syngas from the RWGS assembly, steam, residual carbon dioxide, and all hydrocarbons formed in reactor 342 that are gaseous at reaction temperatures and pressures are fed to a vapor separator 346. The separation is preferably carried out at room temperature, but other temperatures may be used. It is possible that some hydrocarbon gases separate along with water. The residual water and hydrocarbons may then be separated by, as is commonly practiced, for example, distillation or gravimetric analysis.

The residual syngas with a quantity of hydrocarbon gas and residual carbon dioxide is fed to second FT reactor 344. A quantity of liquid hydrocarbons is formed and discharged from the reactor. Unconverted syngas from the RWGS assembly, steam, residual carbon dioxide, and all hydrocarbons formed in the reactor that are gaseous at reaction temperatures and pressures are fed to a steam separator 348. The separation is preferably carried out at room temperature, but other temperatures may be used.

At this point in the process, less synthesis gas is left than at the outlet of FT reactor 342, so the carbon number is C₅Or higher, and the hydrocarbon gas is in the presence of steam and C₅₊Along with the vapor, condenses in separator 348. C_nIs a hydrocarbon having n carbon atoms per mole. C_n+Refers to hydrocarbons having n or more carbon atoms per mole. The condensed liquid is drained and the water is separated by a variety of common processes, such as distillation or gravimetric analysis in water separator 352.

The residue gas from separator 348 is fed to another hydrocarbon separator 354, which includes hydrocarbons having a carbon number of C₃And C₄The hydrocarbon of (1). The hydrocarbons can be condensed and separated from this remaining mixture at a pressure of, for example, 20 to 50bar and at a temperature at which most of such compounds condense. This temperature depends on the amount of other gases in the exhaust gas. When the amount of these gases is larger than the volume of the separable gases, a low temperature, such as that used for carbon dioxide separation, can be used. Then, not only C can be separated₃And C_nHydrocarbons, carbon dioxide may also be separated. These gases are easily separated from each other by changing the pressure and recycling the carbon dioxide to the inlet of the RWGS assembly. The exiting syngas, natural gas components, and residual carbon dioxide are fed to a controlled vent 332 (fig. 11). At equilibrium conditions, the amount of syngas in the vent is significantly less than the other gases, so regardless of the amount of mixture vented, the mixture will contain a smaller amount of syngas than in the recycle loop. The presence of syngas in the recycle loop has the same effect on the complete conversion of the incoming syngas as the presence of carbon dioxide in the recycle loop of the RWGS sub-assembly. DischargingThe amount of syngas in the gas can also be used to control the exhaust ratio.

In other preferred embodiments, more reactors may be used to increase the conversion of syngas, even at different operating parameters, such as low temperatures of 220 ℃ and temperatures of 340 ℃, to obtain a more desirable range of hydrocarbons to form. Different amounts of syngas can be introduced into reactors operating at different conditions to adjust the composition of the hydrocarbons formed, which, in turn, will affect the composition of the fuel, i.e., the relative amounts of gasoline, jet fuel, diesel, etc., after upgrading.

FT reactor

Since the output of the reactor is highly dependent on temperature, the reaction is highly exothermic and requires the removal of large amounts of heat. In a preferred embodiment, as shown in fig. 13, a phase change of water to steam is used in the FT line to remove this heat. The above steps allow the operation of the reactor to be close to isothermal and therefore consistent in output, since the product output of the reactor is highly dependent on temperature, for example within 10 ℃.

Alternative-carbon monoxide conversion

The conversion of carbon monoxide may be achieved by FT treatment 320. There are a number of improvements to this FT process which do not alter the results of the production of hydrocarbon compounds from the synthesis gas, but do significantly alter the composition of the products formed.

For example, the temperature of the reactor may vary within the range of 150 ℃ to 350 ℃. Variations in catalyst type, catalyst bed type, pressure, residence time, and syngas velocity will change the composition of the product formed. At higher temperatures, light hydrocarbon compositions are formed. In one embodiment, 72% of the output comprises C as the carbon number of the gasoline base at 310-340 ℃ using a recycle catalyst₅-C₁₁Comprises 6% heavier hydrocarbons, 8% hydrocarbon gases and 14% alcohols, ketones and acids.

The FT module may be operated at different reactor temperatures by adjusting the water temperature and pressure in the FT-line, the pressure of the FT reactor and other factors affecting the separation of steam from the hydrocarbon gas.

The type of catalyst and its catalyst bed may also be changed from time to match changes in operating characteristics. Two or more reactors connected in series may be used and operated at the same or different temperatures, catalysts and other operating conditions. In addition, it is possible to have two or more parallel reactor trains also operating under different or identical conditions.

With this configuration, a device constructed using the system of the present invention 100 can meet the changing needs of the market after many years of operation.

Hydrogen generation

The present system of the invention 100 further includes a hydrogen import step 400, the hydrogen import step 400 providing hydrogen to drive the conversion 300 of carbon oxides to fuel F. An electrolyzer is the preferred means of providing hydrogen.

Figure 14 shows a portion of an embodiment of electrolyzer 410. The bipolar electrode 412 is preferably used for a series of high voltage and low current electrolysis cells. Current 414 flows through the surfaces of all bipolar electrodes into electrolyte 416, causing electrolysis of the water in each cell.

Each cell may be separated by a gas septum 418. Hydrogen and oxygen are released on opposite sides of each bipolar electrode, collected in the space between the electrode and the membrane and vented for use in the system of the present invention 100.

In a preferred embodiment, use is made of a catalyst having, for example, 5 to 20kA/m²High current density electrolyzer design. And for example 1-3kA/m²This increase in current density results in a smaller size, lighter weight and lower cost electrolyzer. But there is a different energy efficiency due to the much larger overvoltage on the electrodes and the resistive losses in the electrolyte at this increased current density. Electricity of high current densityThe solver used the following constructs and operating parameters:

● operating temperature is 130 ℃, and possibly up to 150 ℃, which reduces overvoltage potential on the electrodes and lowers the resistivity of the electrolyte;

● operating at a pressure in the range of 20-30bar in order to reduce the volume of exhaust gases to benefit the electrolyte conductivity and to reduce evaporation of water and its recirculation;

● the concentration of KOH in the electrolyte is about 30% by weight; and

● the spacing between the electrodes can be made smaller by using a separator material at a temperature range of 130-150 deg.C.

It is possible to obtain a cell voltage around a thermally neutral (isothermal) voltage at a somewhat high current. This means that this thermal neutral potential can be achieved without additional cooling or heating of the cell if there is an electrical energy supply. If the potential is lower, additional heating is required, and if higher, cooling is required.

The reaction water in the high current density electrolyzer cell can be delivered in two ways: delivered in a conventional manner as a liquid or just condensed into water in a pool by steam or as a combination of water and steam. This choice is specifically designed as a function of, among other things, current density, other auxiliary subsystem choices for the electrolyzer, operating voltage.

The choice of a high current density electrolyzer results in other efficiencies of the whole plant due to the lower temperature and especially pressure differences.

The electrolyzer may be powered using existing means as described herein. In a preferred embodiment, fig. 15 depicts the use of several series-connected rectifiers, each of which is separately powered by a phase-shifting transformer. This circuit design results in a high efficiency rectifier that converts the AC (alternating current) voltage in the first EDL to the DC (direct current) required for the operation of the electrolyzer.

The high-pressure electrolyser stack can be divided into several parallel operating banks for convenience of construction, maintenance and safety. The same operation can be performed on the rectifier. The semiconductor rectifiers may be connected in parallel to carry higher currents, or each of such parallel rectifiers may be connected to a separate electrolytic bank. The same operation can be performed for the transformer.

Referring to fig. 15 and 16, three transformers are used, but the transformers do not have to have any phase shift, and a plurality may be used. The high-voltage electrolyzer cell stack can even be directly supplied without any transformer if the output voltage of the power plant is compatible with the voltage required by the stack.

As is common in three-phase power distribution, phase-shifting transformers use more than one phase at the inlet, where the phase shift between the phases is not 0 ° or 180 °, but is typically 120 ° or 240 °. In one example, a transformer 432 having three input phases is powered through an Electrical Distribution Line (EDL). The phase relationship is given in vector diagram 434. This is a typical delta phase arrangement.

The output (secondary) winding of one phase of three-phase transformer 432 typically includes two series-connected, spaced-apart windings. One winding 436 is wound around one input phase winding and the other winding 438 is wound around the other input phase winding. The phase voltage of each secondary winding is in phase with the input voltage of the winding on which it is wound.

By selecting the turns ratio or transformation ratio between the two windings and the polarity, a variety of desired phase shifts can be obtained. Graph 442 shows the transformation ratio and polarity of the transformation of the base input phase voltage by the same value and phase shift of 120 °. The mixed voltage in the output phase XY produces a phase shift compared to the input voltage in the phase XY. In this example, this phase shift is lagging. Graph 444 gives the polarity change of the output, which leads the phase shift.

Rectifier

The present system may utilize a semiconductor rectifier, which is typically a three-phase rectifier. Instead of a semiconductor rectifier, a vacuum tube-based rectifier capable of rectifying larger currents may also be used. The semiconductor rectifiers can be connected in parallel using known coils to achieve a reasonable distribution of current in the parallel semiconductor rectifiers. It is also possible to make the rectifier into more phases by adding more phase legs and connecting all phases from all parallel phase shifting transformers.

Output voltage

The phase shifting transformer and rectifier described herein are combined into a circuit as shown in fig. 15. In a preferred embodiment, three rectifier circuits R are provided in series, each of which is supplied by a phase-shifting transformer T. Such a circuit allows the rectified DC voltage to have very slight voltage fluctuations, with a total amplitude of oscillation of 1.5%, which is beneficial for dimensioning all the components in the circuit of the electrolyzer. Other connections are possible, for example, by connecting these circuits in parallel. Another alternative is to use a different number of circuits with more or less phases and corresponding lower or higher output voltage fluctuations in the circuits.

The resulting voltage is the sum of all three rectifier voltages. Fig. 17 depicts a voltage line graph 452 of a three-phase rectifier on a scale. For one period of the distribution line voltage (360 °), there are six sinusoidal waveform rectification poles from positive half cycle to negative half cycle of each phase. The depth of the voltage fluctuation is cos (30 °) to 0.866, or 13.4% of the peak voltage. In a circuit with three rectifiers, the phase shift is maintained between 20 leading and lagging phases. In this case, the depth of the voltage fluctuation is cos (10 °) 0.985, or 1.5% of the peak value of the voltage diagram 454.

This fluctuation is sufficient for low current fluctuations in the electrolyzer cell, which in turn enables more utilization of the surface of the electrolyzer cell and the lower power rating of the transformer and rectifier.

The high-pressure section of the electrolyzer can be divided into several groups operating in parallel, for convenience of construction, maintenance and safety, among other problems. The same operation can be performed on the rectifier. The semiconductor rectifiers may be connected in parallel to carry a stronger current, or such parallel rectifiers may be separately connected to separate groups of electrolyzers. The same operation can be performed for the transformer.

Post-treatment

Typically, the output of the conversion step 300 is a series of hydrocarbons. A post-treatment step 500 is provided to upgrade the hydrocarbons to obtain the desired fuel F mixture. The process can use existing technology to convert the hydrocarbon stream from the FT sub-assembly into the desired fuel and, if desired, other products. The inputs and outputs of such a device are given in fig. 18. The upgrading process generally comprises the following steps: the heavy fraction of the FT (lube oils and waxes) is hydrocracked to yield fuels mainly in the diesel and gasoline range. It should be noted that the refining requirement for hydrogen can preferably be met with hydrogen from the electrolyzer.

Combustor-generator

FIG. 19 illustrates a preferred embodiment combustion system 520. The material input to the combustor may be the gas exhausted from the FT reactor assembly and/or the residue from the refinery and/or natural gas compounds. All of these compounds may be combusted in the gas turbine generator 522 with a relatively small portion of the oxygen coming from the electrolyzer. The output gases from the turbine exhaust are steam and carbon dioxide. The steam is separated into water and residue-carbon dioxide, which is re-fed into the gas mixer with the introduced carbon dioxide. This is yet another gas recirculation loop of the system of the present invention 100.

The electricity generated by the generator is fed back to the transmission line and further delivered to the electrolyzer.

Thus, the system produces little to no waste, only the desired fuel and the amount of oxygen required to combust the fuel.

Such a plant is less sensitive to incomplete conversion of the syngas in the FT sub-assembly, since the generated electricity is re-fed back to the formation of hydrogen. Furthermore, such a plant is less sensitive to the separation efficiency of the carbon dioxide separation in the RWGS sub-assembly, since the carbon dioxide is recycled to the inlet of the RWGS sub-assembly.

Gas separation and general treatment

In the given process, there are several places where it is necessary to separate some of the gas from the gas mixture, or where simple adjustments of gas parameters such as temperature and pressure are necessary to adapt it to the upstream process.

One advantage of the present system is its energy efficient gas treatment. There are generally two energy efficient thermodynamic methods for gas treatment. The first method is an adiabatic process when all the external work is converted to or from gas energy. The second method is an isothermal method when all the external work is converted to or derived from heat.

It will be appreciated by those skilled in the art that these are all ideal methods. In practical applications, there are some temperature variations in the ideal isothermal process. These changes make the process only near isothermal. As used herein, the term "isothermal" shall include operations or processes that are "close to", "approximate" or other such terms in order to adjust for ideal isothermal operation, and more particularly to variations in absolute temperature, measured in ° K, within ± 10% of the ideal isothermal temperature in an actual isothermal process. Similarly, in practical adiabatic methods, some thermal energy is included in addition to the external work that is primarily performed. These "real" insulation methods are similar to "near" and/or "near" insulation and include thermal energy that is also within ± 10% of the energy of the external work from the ideal process.

The invention preferably comprises one or more units for "isothermally" varying the gas pressure, said units incorporating a range of ± 10% of the ideal isothermal process temperature. As mentioned above, the present invention preferably includes one or more units for "adiabatically" varying the temperature of the gas, which units incorporate a range of + -10% of the ideal adiabatic process.

As shown in fig. 20, a unified gas separation diagram using both processes is presented. First, the three processes 610-614 condition the gas mixture to separate one or more components of the gas mixture via condensation in the condenser 616. The three processes 618-622 then condition the remaining gas mixture for further processing. The separated gas or gases are in the liquid phase in condenser 616. If further processing in the gas phase is desired, some of the gas is vaporized in vaporizer 624 and then conditioned for further processing by the process of 626-630.

The main functions of each of the processes 610, 618, 620 and 626, 630 are the same. The processes all focus on conditioning the gas in an adiabatic process to avoid any phase change of the gas mixture components to a liquid or solid. Each process starts with isothermally adjusting the pressure. Secondly, the gas or gas mixture is adiabatically treated to change the temperature. After this treatment, the pressure is varied by a final isothermal process, according to the requirements of the further treatment. In general, the pressure is changed isothermally, and the temperature is changed adiabatically.

Fig. 21 shows adiabatic machines, one of which raises temperature and pressure by compression using electric power from a distribution line, and the other of which lowers temperature and pressure and generates electric power to the distribution line. In a preferred embodiment, the power line serves as the source recipient of electricity that is transferred to or obtained from the adiabatic process. The compressor 632 is preferably a turbine driven by an electric motor, and the expander 634 is also preferably a turbine driving an electric motor generator. Much like other generators used in power grids, the generator must be synchronized to the voltage frequency and phase in the transmission line and matched to the voltage value. Other types of compressors and expanders than turbines may be used.

FIG. 22 shows an isothermal machine, one for increasing pressure and the other for decreasing pressure. In an elevated pressure isothermal machine, a compressor 636 driven via an electric motor is used, and the resulting gas mixture, which receives electricity from the power transmission line, is compressed and cooled. Heat is removed by cooler 638. The amount of heat removed is theoretically equal to the power delivered by the transmission line. For large pressure variations, several isothermal pressure transducers in series may be used. In this case, the isothermal pressure transducer is called an isolated compressor (isolated compressor). They are isolated from the cooler.

The reverse process is used to reduce the pressure isothermally. In this case, the gas mixture is subjected to an expansion which simultaneously lowers the pressure and the temperature of the gas mixture. The change in temperature is compensated by heating. Furthermore, the amount of heat transferred to the mixture is theoretically equivalent to the energy transferred to the transmission line by the generator driven by expander 640. Preferably, a turbine is used as both the compressor and the expander, but other types may be used.

The system uses a cooler 638 and a heater 642 in an isothermal machine. The cooler 638 and heater 642 are essentially heat exchangers. For isothermal operation, it is preferred to use phase changes of the working fluid to transfer heat to or remove heat from the gas passing through these heat exchangers. The above operation allows the system to handle heat with near zero temperature variation.

Turning to FIG. 7, several examples of energy distribution lines used in the present invention are shown. The first line is the transmission line that delivers electricity to all uses-the electrolyzer and all electric motors described below, and receives electricity from all sources-the power generation plant and all internal generators described below.

The other lines are heat distribution lines. The heat distribution lines deliver or receive heat from different sources and use the heat. Each line preferably comprises two sections, a liquid section and a vapor section. When heat has to be transferred through the line, the steam is introduced into a heat exchanger dedicated to receiving this heat, where it is subsequently condensed and released, and the condensate is conveyed to the other half of the heat distribution line. When heat has to be received, the reverse process is used to evaporate the liquid into a vapour.

Examples of temperatures at which the phase transition occurs in the present method are:

a) a temperature-heat distribution line RWGS (RWGS line) of the RWGS reactor;

b) temperature-heat distribution line FT (FT line) of the FT reactor;

c) temperature-heat distribution line E (E-line) of the water in the electrolyzer;

d) room temperature-heat distribution line a (a line); and

e) temperature-heat distribution line C (C-line) for carbon dioxide separation.

The following are examples of working fluids for these lines:

a) ethylene glycol for RWGS lines;

b) water for the FT line, or a substitute at higher temperatures, such as ethylene glycol;

c) water for the E line;

d) ammonia for line a; and

e) ethylene for C line.

Fig. 23 shows a combination of a condenser and an evaporator, and the motors 616 and 624 of fig. 20. The condenser component is a heat exchanger 652, wherein the gas mixture passes through the heat exchanger 652. The heat of the gas mixture is removed by evaporation of the working fluid via the evaporator 654 and this operation causes condensation of the desired mixture components pre-treated for this condensation in the collector section 656 of the heat exchanger 652. The liquefied gas is collected and discharged into a vaporizer where the reverse process takes place. Heat is transferred from the same heat distribution line to the evaporative heat exchanger. In theory, this condensation and evaporation process of the separated gases is energy neutral.

Fig. 24 shows how the power is distributed and recycled. Line 1 is a three-phase power distribution line. It is powered according to the main power supply of fig. 6, preferably by a fast breeder reactor. It may also be powered by the residual energy released in the FT reactor by generator 716 of fig. 27. The electrolyzer cell of figure 14 is the primary electricity consumer. All expander generator means used in adiabatic temperature changes and isothermal pressure changes supply power to the pipeline, and all compression motors used in adiabatic temperature changes and isothermal pressure changes supply power to the pipeline. Virtually all other auxiliary engines and generators are connected to this line. We present some areas in which different motors and generators are used.

Figure 25 shows how the heat distribution and recirculation lines are used. In the RWGS lines, heat is transferred by a heat pump 710 shown in fig. 27, which derives from the energy released in the FT reactor. As depicted in fig. 10, this heat is used to heat the RWGS reactor. All of the heaters and coolers given in figure 22, which are used in the introduction of these reactors and the isothermal pressure change of the effluent gas, use or transfer heat from or into the line.

In the FT lines, heat is transferred via heat exchanger 714 of fig. 27, which results from the energy released in the FT reactor. Figure 22 shows all the heaters and coolers used in the introduction of these reactors and the isothermal pressure change of the effluent gas, which use or transfer heat from or into the line.

In the electrolyzer line, heat is transferred via heat exchanger 712 of fig. 27, which derives from the energy released in the FT reactor. The primary use of heat is the heater/evaporator of fig. 28 for the electrolyzer water. Figure 22 shows all the heaters and coolers used in the introduction of these reactors and the isothermal pressure change of the effluent gas, which use or transfer heat from or into the line.

Figure 26 shows two additional heat distribution and recirculation lines. One of these is a pipeline operating at room temperature. Figure 22 shows all the heaters and coolers used at room temperature in introducing isothermal pressure variations with the effluent gas, which use or transfer heat from or into the line. Fig. 23 shows all evaporators and condensers of a gas separator, such as a steam separator, taking heat from or transferring heat to the line. There is also an excess heat collection end of the heat pump carrying heat from the carbon dioxide separation line. All unused heat in the entire plant will be transferred to the pipeline and dissipated primarily as waste heat.

Another line in fig. 26 is a carbon dioxide separation line. Figure 22 shows all the heaters and coolers used in introducing and exiting the isothermal pressure variations of the gas at temperatures close to the carbon dioxide liquefaction separation, which use or transfer heat from or into the pipeline. Fig. 23 shows all the evaporators and condensers for carbon dioxide separation, which take heat from the line or transfer heat to the line. The carbon dioxide separation line is used not only to separate carbon dioxide from the effluent gas at the outlet of the RWGS reactor, but also to separate C from the effluent gas of the FT reactor₃And C₄Hydrocarbons and residual carbon dioxide. There is also an excess heat collection end of the heat pump that carries excess heat from the carbon dioxide separation line into the surrounding lines.

Preferred gas separation and treatment

Carbon dioxide is typically delivered to the plant through a line having a gas line pressure of 50bar and at room temperature. For feeding into the RWGS sub-assembly, the carbon dioxide should be heated to the temperature of the RWGS, in this embodiment 400 ℃, and at an operating pressure of e.g. 25 bar. To achieve this, all or part of the process of 610-614 in FIG. 20 may be used.

Hydrogen from the electrolyser is produced at temperatures of 130 ℃ > 150 ℃ and pressures of 20-30bar and must be adjusted for input into the RWGS sub-assembly. To achieve this, all or part of the process of 610-614 in FIG. 20 may be used.

At the outlet of each RWGS reactor, the steam has to be separated. This operation must be carried out at low temperature in order to remove most of the steam. In this embodiment, the low temperature is room temperature. To achieve this separation, all or part of the processes 610, 614 and 616 of FIG. 20 may be used. Additionally, the processes 614-616 may be combined in one machine. After separation, the gas must be reconditioned for further processing using all or part of the processes 618 and 622 of FIG. 20.

Carbon dioxide present in the outlet effluent stream of the third vapor separator in the RWGS sub-assembly may be separated using a variety of processes such as amine absorption, carbonate absorption, pressure swing absorption, adsorption, gas permeation, and additive assisted cryogenic technologies (e.g., Ryan-Holmes) or three-phase cryogenic technologies (CFZ). When liquefaction is used to separate most of the carbon dioxide, all or part of the process of FIG. 20 may be used. In this embodiment, the temperature T₁Is room temperature, condensation temperature T₃At a temperature T in the range of-55 DEG C₄Equal to the FT reactor temperature, in this embodiment the FT reactor temperature is 220 deg.C, and the temperature T₆Equal to the temperature of the RWGS reactor, in this embodiment the RWGS reactor temperature is 400 ℃.

The hydrogen entering the FT reactor sub-assembly is coming from the electrolyzer at a temperature of 130-150 ℃ and a pressure of 20-30bar and must be adjusted to 220 ℃ and 20bar as preferred in this embodiment. To accomplish this, all or a portion of the process of 610-614 of FIG. 20 may be used.

If carbon monoxide is supplied to the FT sub-assembly, it is possible to transport it via a pipeline at a typical pressure of 50bar and room temperature. For input to the FT sub-assembly, the carbon monoxide should be heated to the temperature of the FT, which in this embodiment is 220 ℃, and expanded to the operating pressure, e.g. 20 bar. To achieve this, all or part of the process of 610-614 of fig. 20 may be used.

In this embodiment, the steam is separated at room temperature at the outlet of each FT reactor. To accomplish this separation, all or a portion of the processes of 610, 614, and 616 of FIG. 20 may be used. Additionally, the processes 614-616 may be combined in one machine. After separation before the second FT reactor, the gas must be reconditioned for further processing using all or part of the process 618-622 of fig. 20.

After the second FT reactor, steam is also separated at room temperature along with residual heavy hydrocarbons. To accomplish this separation, all or a portion of the processes of 610, 614, and 616 of FIG. 20 may be used. Additionally, processes 614 and 616 may be combined in one machine.

Following this separation, C must be separated using all or part of the process 610-616 of FIG. 20₃And C₄A hydrocarbon gas. Condensation can be carried out at room temperature when the carbon dioxide and synthesis gas content is low. Otherwise, it must be carried out at a lower temperature rather than at a higher pressure. In a preferred embodiment, there is a line for C for carbon dioxide condensation and this line is for C in the mixture₃、C₄And CO₂Condensation of (2). Thus, by varying the pressure of the separated liquid, CO₂Will first evaporate and be processed by process 624-630 of fig. 20 for input into the RWGS component. C₃And C₄The condensate of the compounds may be used in liquid form or, if desired, may be vaporized and adjusted to a gas using all or part of the process of 624-. Finally, all or part of the 618-622 process must be reused for residual C₁And C₂Hydrocarbons, syngas, and other gases are conditioned for input to the controlled release 322.

Then, in the circulation loop of the FT sub-assembly, the gas must be transferred from the controlled release input conditions of room temperature and pressure to the input conditions of the first FT reactor-220 ℃ and 20bar in this embodiment. Further, all or a portion of the processes of 610-614 of FIG. 20 may be used.

Finally, if oxygen from the electrolyzer is delivered for use outside of the apparatus, it must also be regulated. The oxygen is passed from the electrolyzer at a temperature of 130 ℃ and 150 ℃ and a pressure of 20-30 bar. For transport through the pipeline, the oxygen has to be adjusted to a typical pipeline pressure of 50bar and room temperature. To accomplish this, any or all of the processes of 610-614 of FIG. 20 may be used.

Similarly, for oxygen delivery to the combustor-generator, steam separation of the combustor-generator, and carbon dioxide re-return inlet delivery, the processes described herein for such purposes as well as the process presented in fig. 20 may be used.

Similarly, the hydrogen used in the purification may be treated in the same manner as described, but for different output temperatures and pressures.

Recycling of heat from a fischer-tropsch sub-assembly

The exothermic heat of reaction in the fischer-tropsch reactor is the primary source of energy in the plant driving all gas treatment and an additional source of electrical energy for water electrolysis. As shown in fig. 27, we present a cooling loop for the FT reactor. In this embodiment, the steam used to cool the working fluid of the reactor is distributed to be condensed in several heat engines.

The first machine 710 is a heat pump that pumps heat generated by the condensation of steam to the RWGS heat distribution line. At the outlet of the condenser, the working fluid is in the liquid phase at the condensation temperature.

The second machine is a heat exchanger, which heats the water to the temperature of the electrolyzer. In addition, the heat is transferred by condensation of the working fluid. The process may use all or part of 610-616 of figure 20 and the generated electricity is delivered to the electrolyzer through the distribution lines. The liquid exiting the FT line is reheated and compressed to match the temperature and pressure of the FT reactor.

If such heat is required to balance the heat flow in this line, a third machine transfers heat to the FT heat distribution lines by condensation.

The remaining steam drives the electrical generator 716, with the outlet temperature preferably being at room temperature level. The electrical energy is transferred to a distribution line and via this line to an electrolyzer for addition to the energy transferred by the power plant. The liquefied working fluid is recompressed and reheated to the pressure and temperature of this fluid from the other condenser and returned to the FT reactor by evaporation to cool the fluid. The water is reheated using heat from the FT heat distribution line. An example of the working fluid is water. At higher FT operating temperatures, other fluids such as ethylene glycol may be used.

Water feed to the electrolyzer

The inventors present in figure 28 the treatment of the water fed to the electrolyzer. Water comes from a variety of sources. Preferably, equal amounts of water from other processes are recycled in the plant, particularly water from the RWGS reactor steam separator, water from the FT reactor steam separator, water from the combustor-generator steam separator, and any water collected in the refining. All these water and incoming water streams are at different temperatures, most of which are around room temperature, but the water of the electrolyzer is at 130-150 ℃ and compressed to 20-30 bar. Furthermore, above a certain high current density the electrolyzer has to be cooled and below a certain current density the electrolyzer has to be heated.

In a preferred embodiment we use heating/boiling and compression of water to adjust this water to said temperature and electrolyzer pressure, i.e. the water absorbs or transfers said excess heat from the electrolyzer. When performed in a heat transfer manner, a portion of the water may even be evaporated to transfer more heat to the water of the electrolyzer via condensation. When performed as heat absorption, the water temperature is lower than the temperature in the electrolyzer. For vapor compression, all or a portion of the processes of 610-614 of FIG. 20 may be used. For the heating of the water, the heat of the E line is used.

Main control

The electronic control is inherent to the system of the present invention 100. The control includes a physical layer and a control computer with software incorporating control algorithms. The physical layer includes a sensor and a driver. Each functional module of the invention 100 has sensors that relate to functions such as, inter alia, gas flow or gas or liquid flow density, pressure, temperature, speed.

The drives are pumps for the condenser and evaporator, a generator driven by the expansion turbine, an electric motor driving the compressor, gas and liquid flow throttling valves or valves, mechanical regulators such as vanes in the turbine, and other components required to perform a certain function.

It is preferable to use a distribution computer with redundant processing to ensure the safety and timeliness of the control.

The main control functions of the present invention 100 include:

● control the complete conversion of the carbon dioxide introduced into the RWGS assembly to carbon monoxide;

● controlling the discharge of the Fischer-Tropsch module export gas to maintain the hydrocarbons or other gases in the export stream at a predetermined concentration;

● control hydrogen supplied to the inlet of the RWGS assembly;

● control hydrogen supplied to the inlet of the FT assembly;

fig. 29-32 depict different systems of the present invention 100 for controlling a process 1500. FIG. 29 depicts control of the RWGS component. The main purpose of the RWGS assembly control is to convert the introduced carbon dioxide to carbon monoxide as fully as possible using feedback control.

The flow of the introduced carbon dioxide is controlled via a throttle 1502, which throttle 1502 has a regulating element driven by an electric drive 1504. A flow meter 1506 for introducing carbon dioxide is provided after the throttle valve 1502. A second flow meter 1508 for carbon monoxide is provided at the outlet of the RWGS assembly. The outputs of the two flow meters are fed to the inputs of the error amplifier 1512 as shown, and those inputs are calibrated at the molar rate. The output of such an amplifier drives a power driver 1504.

If the amount of carbon monoxide becomes lower than the amount of carbon dioxide, the output of the error amplifier reduces the drive of the throttle and reduces the flow of carbon dioxide, resulting in a smaller difference between the two flows with such a negative feedback loop error bandwidth.

Fig. 30 shows the control of the FT assembly. The primary purpose of controlling the FT assembly is to maintain the hydrocarbons or other gases, such as syngas, at the assembly outlet at a level that achieves the ultimate goal of minimizing syngas emissions from the FT assembly recycle loop.

A control gas flow meter 1522 at the FT subassembly outlet is placed before the splitter 322. The signal from the flow meter is fed to an error amplifier 1526 where the signal from the flow meter is compared to a reference level. The output of this amplifier is supplied to a power driver 1528, which power driver 1528 controls a flow control element 1532 of the shunt 322.

This is a negative feedback loop and is in a steady state, with the flow control device 1532 providing sufficient effluent gas to maintain the amount of control gas at a steady state as dictated by the reference level. If more gas is controlled then the flow control means is opened more and the excess is reduced and vice versa.

Fig. 31 shows the control of hydrogen supply to the RWGS subassembly. The primary purpose of this control is to target the desired H at the RWGS sub-assembly outlet₂the/CO ratio supplies sufficient hydrogen.

The flow rate of the introduced carbon dioxide is measured by the same flow meter 1506. There is also another hydrogen flow meter 1544. The output of the carbon dioxide flow meter is fed to a multiplier 1546, which multiplier 1546 amplifies the signal by the desired hydrogen to carbon dioxide ratio at the RWGS sub-assembly inlet. In a preferred embodiment, said ratio is between 1.5 and 3.2. Signals from the amplifier and hydrogen flow meter are fed back to the error amplifier 1548 and those inputs are calibrated at molar rate. The output of this amplifier is fed to a driver 1552 to control a hydrogen flow regulator 1554, which regulator 1554 may be as simple as a throttle valve.

Hydrogen is supplied by an electrolyzer. The electrolyzer is a negative feedback loop. When the output value of amplifier 1548 is zero, the static conditions of the electrolyzer allow hydrogen to flow. If the amount of carbon dioxide supplied decreases, the output signal of amplifier 1548 will decrease the flow via 1554. And vice versa.

FIG. 32 shows control of hydrogen supply at the inlet of the FT sub-assembly. The primary purpose of this control is to adjust the hydrogen to carbon monoxide ratio between separator 328 and splitter 332 for the desired hydrocarbon production in the FT sub-assembly.

The flow of carbon monoxide is measured by flow meter 1562 and the flow of hydrogen is measured by flow meter 1564. The two flow meters were calibrated at molar rates. The signal from the flow meter 1562 is supplied to a multiplier 1566 where the amplification factor represents the desired ratio of hydrogen to carbon monoxide at the outlet. In a preferred embodiment, the ratio is about 2, which is similar to the ratio at the inlet of the FT sub-assembly and varies as a function of the operating conditions of the particular type of FT reactor described herein.

The output values of the multiplier 1566 and the flow meter 1564 are supplied to an error amplifier 1568. The output of this amplifier is supplied to a control driver 1572, which control driver 1572 electrically drives an adjustment mechanism of the hydrogen flow control device 1574, which may be as simple as a throttle valve. Hydrogen is fed by the electrolyzer to the inlet of the FT sub-assembly through flow controller 1574.

This is a negative feedback loop. When the output of amplifier 1568 is zero, the amount of hydrogen delivered to the FT sub-assembly is just enough to achieve the desired amplifier coefficient. If more hydrogen is detected at the FT sub-assembly outlet, flow control device 1574 will adjust to pass less hydrogen and vice versa.

And a water level controller is also arranged in the pool area. The water level controller adjusts a drainage mechanism installed in the drainage pipe. The level controller is a conventional controller that maintains the liquid level in the storage tank by draining water.

Use of electric energy

Table 1 summarily describes the efficiency and power usage calculations described herein.

General table of energy flow (kJ)
					Carbon oxide feed	CO2	CO2	CO	CO
Limit of efficiency	Minimum size	Maximum of	Minimum size	Maximum of
					Energy for electrolysis	853	753	578	510
Energy for RWGS reaction	41	37	-	-
					Energy from FT reaction	(146)	(176)	(146)	(176)
Energy for treatment	200	150	133	100
					Total Electric Energy (TEE)	948	764	565	434
High Heating Value (HHV) of hydrocarbon compounds	670	680	670	680
					Energy efficiency,% (HHV/TEE)	71	89	119	157
Electric energy per unit high heat value (TEE HHV)	1.4	1.1	0.84	0.64
					TEE excess (deficiency)%	40	10	(16)	(36)

In table 1, the calculated values for the two carbon oxides are given. For each carbon oxide, all values that produce the lowest efficiencies as explained in the exemplary description below are summarized in one column, and all values that produce the highest efficiencies are summarized in another column. Efficiency is defined as the ratio of the High Heat Value (HHV) of hydrocarbon combustion to the Total Electrical Energy (TEE) supplied to the process and plant from an external source. The electrical energy used is defined as the reciprocal value of the efficiency, ie the TEE to HHV.

In the last row of table 1, excess or insufficient power is given. For example, using carbon dioxide as an input and with the lowest efficiency, electrical energy of 40% more than the high heat value of combustion of the produced hydrocarbon compounds would be required. With carbon dioxide as an input and with the highest efficiency, only 10% more electrical energy needs to be used.

In the case of carbon monoxide as input, substantially less electrical energy is obviously required, since carbon monoxide has a certain combustion energy (compared to carbon dioxide which does not have combustion energy). For this reason, it is such that with carbon monoxide as an input and with the lowest efficiency, 16% less electrical energy will be required than the high heat value of combustion of the hydrocarbon compounds produced. With carbon monoxide as input and with the highest efficiency, 36% less electrical energy will be required.

The following is a description of the contents of table 1, wherein for simplicity all energy is given in terms of one mole of carbon dioxide converted to hydrocarbon compounds.

The electrical energy required to electrolyze water as a function of temperature and at a current density providing isothermal operation is between 274 and 286kJ per mole of hydrogen. In a preferred embodiment, it is estimated that it will be 275 kJ. 3.1 moles of hydrogen would be required to recycle 1 mole of carbon dioxide and therefore 853kJ of electricity would be required for isothermal operation. For lower current densities, the amount of electrical energy will be lower, e.g. up to 100kJ or less. In such a case, the shortfall will be accommodated by other processes in the device. Of course, for higher current densities, more electrical energy will be required and additional heat must be removed. A portion of this heat may be recycled for electrokinetic feeding to the electrolyzer via the generator. Of course, it is not possible to recover all the heat and the total energy consumption will increase.

The RWGS reaction is moderately endothermic and requires 37-41kJ per 1 mole of carbon dioxide converted as a function of operating conditions. This is another process that can use the heat generated in the device.

The Fischer-Tropsch reaction is highly exothermic and produces 146-. This reaction is the primary source of heat in the apparatus, method and system.

Other energy requirements come from difficult to recover energy, such as bearing losses, motors, transformers, rectifiers, radiation and convection losses, etc., dissipated in the process, and enthalpy differences from the incoming and outgoing products. It is important to note that this is simply the loss in the reversible process of gas and liquid according to the process of figure 20. For this reason, it is estimated that these losses are in the range of 150-.

The output of the FT reactor is a mixture of hydrocarbon compounds with different combustion energies. From this estimate, the high calorific value of the combustion is used when the water is used for recirculation. This energy is about 670-680kJ per 1 mole of carbon dioxide converted in the mixture of compounds.

All of these values are used to calculate the amount of electrical energy required to be input per unit of high heating value for combustion of the hydrocarbon compounds produced using electrical energy generation in the processes and systems described herein. When only carbon dioxide input is used, the range is between 1.4 and 1.1. That is, this means that the system requires the extraction of 10-40% more electrical energy from an external source than the high heating value of the combustion energy of the hydrocarbon compounds, the end products of which are carbon dioxide and water.

This energy usage is also advantageous compared to the energy usage of coal to liquid conversion, i.e. in the 2.5 range, and the energy usage in gas to liquid conversion (GTL) is in the 1.7 range. In both cases, the input is the high calorific value of the coal or gas.

In the present system, less electrical energy is used when using carbon monoxide from an external source than when using carbon dioxide. In this case, the system will require less than 1 mole of hydrogen and the reverse water gas shift reactor does not require heat. The energy required for the water electrolysis will then be in the range 275kJ/mol to 275kJ/mol multiplied by 2.1 moles to give 578 kJ. Furthermore, since the RWGS process and the carbon dioxide separation process are omitted, the amount lost in the gas treatment process will be reduced by at least one third, and thus will be 100-. This results in the required external electrical energy being between 0.64 and 0.84 of the high heating value of the hydrocarbon compounds.

In order to achieve this advantageously low use of the external power supply, the following main internal energy flows are implemented:

● from Fischer-Tropsch to RWGS using a heat pump;

● the heat of condensation as steam is transferred from the Fischer-Tropsch to the electrolyser if required;

● is used by the heat transported to all processes by the Fischer-Tropsch;

● sent from the Fischer-Tropsch to the electrolyser to use the residual heat for power generation;

● from the internal gas expander-generator to the internal compressor-engine; and

● use the phase change of the working fluid to be delivered by an internal gas/liquid cooler to an internal gas/liquid heater.

Preferred alternatives for the entire system

In addition to the use of an FT reactor to convert syngas to liquid fuels, it is also desirable to produce methane, the major component of natural gas. The following catalytic reactions can be used for this purpose:

CO+3H₂→CH₄+H₂O (7)

in addition, other different hydrocarbon materials may be produced from the syngas, as is well known in the art.

In another preferred embodiment of the invention, a device may be placed near the natural gas field to capture carbon dioxide and deliver CH₄. In many natural gas wells, there is a significant amount of carbon dioxide, perhaps a portion of the carbon dioxide is blocked for that reason. In some cases, the disclosed RWGS and FT processes can be bypassed using the Sabatier reaction described below:

CO₂+4H₂→CH₄+2H₂O (8)

in this process, the heat released is similar to that released in the FT process (per mole of carbon oxide) and conversion carried out at about 300 ℃.

Two different reactions may be used instead of the disclosed FT and RWGS processes. The first is the Lurgi process (Lurgi process), also known as the Carnol process. The second is the Methanol To Gasoline (MTG) process.

Although in the reverse water gas shift reaction carbon dioxide reacts with hydrogen to produce carbon monoxide and water, the lurgi or Carnol process uses the same reactants as the reverse water gas shift reaction, using different catalysts and reaction conditions to produce methanol. Thus, in another embodiment of the invention, the RWGS reaction may be replaced with a lurgi or Carnol method as follows:

CO₂+3H₂→CH₃OH+H₂O (9)

the methanol produced by this reaction is then used in an MTG process, which has a high selectivity for the formation of gasoline-based light hydrocarbons.

Although the present invention has been disclosed in its preferred form, it will be apparent to those skilled in the art that various modifications, additions and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents as set forth in the following claims.

Claims (22)

1. A process for the production of hydrocarbon compounds comprising the steps of:

a) generating hydrogen gas from water in an electrolyzer using electrical energy;

b) supplying at least a portion of the produced hydrogen and carbon dioxide externally provided from any source to a reverse water gas shift reactor to produce synthesis gas as a mixture of carbon monoxide and hydrogen with some residual carbon dioxide and water as a by-product; and

c) feeding the discharged synthesis gas from the reverse water gas shift reactor to a fischer-tropsch reactor to produce a mixture of hydrocarbon compounds and a water byproduct;

is characterized in that:

b1) the reverse water gas shift reactor comprises one or more reactors connected in series with intermediate steam separation; and

d) at least a portion of the excess thermal energy from the fischer-tropsch process is transferred to one of the other process steps in the process that require energy.

2. The process of claim 1, further comprising separating at least a portion of the carbon dioxide gas from the effluent stream of the at least one reverse water gas shift reactor and returning it to the inlet of the at least one reverse water gas shift reactor.

3. The process of claim 1 or 2, wherein the operating temperature of the reverse water gas shift reactor is between 350 ℃ and 500 ℃.

4. The process of claim 1 or 2, wherein the fischer-tropsch reactor comprises one or more serially connected fischer-tropsch reactors with at least intermediate steam separation.

5. The process of claim 4 wherein each Fischer-Tropsch reactor is operated at a different temperature.

6. The method of claim 1 or 2, further comprising a process of combusting one or more of the hydrocarbon compounds in a combustor generator to produce at least a portion of the electrical energy.

7. The process of claim 1 or 2, wherein at least a portion of the excess thermal energy from the fischer-tropsch process is transferred to the reverse water gas shift reactor using a heat pump.

8. The process of claim 1 or 2, further comprising varying the temperature of the gas in the process "adiabatically" which incorporates a range of ± 10% of an ideal adiabatic process; and/or "isothermally" varying the pressure of the gas in the process, which incorporates a range of ± 10% of the ideal isothermal process temperature.

9. The method of claim 1 or 2, further comprising a heat distribution process, wherein a heat distribution line connecting two or more of the process steps is provided for receiving heat from the process steps or for supplying heat to the process steps to reduce the need for a surplus of such heat or thermal energy to be supplied externally.

10. The process of claim 9 wherein at least some of the heat distribution lines pass through one or more heat exchangers used in said process steps for the exchange of heat or thermal energy, wherein the working fluid in the heat distribution lines that transfers heat or thermal energy is in a gaseous state upstream of said heat exchangers and in a liquid state downstream of said heat exchangers.

11. A system for producing hydrocarbon compounds, comprising the following units:

a) an electrolyzer that generates hydrogen from water using electrical energy;

b) a reverse water gas shift reactor to which at least a portion of the produced hydrogen and carbon dioxide provided externally from any source are supplied to produce synthesis gas as a mixture of carbon monoxide and hydrogen with some residual carbon dioxide and water as a by-product; and

c) a fischer-tropsch reactor to which is fed synthesis gas discharged from the reverse water gas shift reactor to produce a mixture of hydrocarbon compounds and a water by-product;

is characterized in that:

b1) the reverse water gas shift reactor comprises one or more reactors connected in series with intermediate steam separation; and

d) a line for transferring at least a portion of the excess thermal energy from the Fischer-Tropsch process to one of the other units in the system requiring energy.

12. The system of claim 11, further comprising a unit for separating at least a portion of the carbon dioxide gas from the at least one reverse water gas shift reactor effluent stream and returning it to the at least one reactor inlet.

13. The system of claim 11 or 12, wherein the operating temperature of the reverse water gas shift reactor is between 350 ℃ and 500 ℃.

14. The system of claim 11 or 12, wherein the fischer-tropsch reactor comprises one or more serially connected fischer-tropsch reactors with at least intermediate steam separation.

15. The system of claim 14 wherein each fischer-tropsch reactor is operated at a different temperature.

16. The system of claim 11 or 12, further comprising a combustor generator for combusting one or more of the hydrocarbon compounds to produce at least a portion of the electrical energy.

17. The system of claim 11 or 12, further comprising a heat pump for transferring at least a portion of the excess thermal energy from the fischer-tropsch process to the reverse water gas shift reactor.

18. The system of claim 11 or 12, further comprising one or more units for "adiabatically" changing the temperature of the gas, which incorporates a ± 10% range of an ideal adiabatic process; and/or one or more units for "isothermally" varying the gas pressure, which incorporates a ± 10% range of the ideal isothermal process temperature.

19. The system of claim 11 or 12, further comprising a heat distribution line connecting two or more of the process units, the heat distribution line for receiving heat from the process units or for supplying heat to the process units to reduce the need for externally supplied such heat or a surplus of heat energy.

20. The system of claim 11 or 12, wherein power is supplied to the electrolyzer, the power supply comprising a rectifier connected to a multiphase power supply having three phases or more.

21. The system of claim 20, wherein the rectifier is powered by a phase shifting transformer.

22. The system of claim 11 or 12, further comprising a nuclear power generation device that generates electrical energy.