HK1062931B - Single chamber compact fuel processor - Google Patents

Description

Single reaction chamber compact fuel processor

Technical Field

Fuel cells utilize chemical oxidation-reduction reactions to generate electrical energy, which is significantly superior to other forms of power generation in terms of cleanliness and efficiency. Typically, a fuel cell uses hydrogen as its fuel and oxygen as its oxidant. The amount of electricity generated is proportional to the amount of reactant consumed.

One of the major drawbacks that prevent fuel cells from gaining widespread use is: there is a lack of a widespread hydrogen storage infrastructure. The volumetric energy density of hydrogen is relatively low and it is more difficult to store and transport than the hydrocarbon fuels currently employed by most power generation systems. One solution to this problem is to use a reformer to convert hydrocarbons into a hydrogen-rich gas stream, which is then used as a feed for a fuel cell.

Background

For most fuel cells, hydrocarbon-based fuels such as natural gas, LPG, gasoline, diesel, etc. require multiple reforming processes to be the fuel source. The prior art uses multiple stages of processes that combine an initial conversion process with several purification processes. The initial process is mostly a common steam reforming process (SR), autothermal reforming (ATR), catalytic partial oxidation reforming (CPOX), or non-catalytic partial oxidation reforming (POX). The purification process usually consists of the following processes: desulfurization, high temperature water gas shift, low temperature water gas shift, selective CO oxidation, or selective CO methanation. Other optional processes include processes performed through hydrogen selective methanation reactors and filters.

Despite the above-described designs, there remains a need for a simple system unit that can be used with a fuel cell for converting a hydrocarbon fuel into a hydrogen-rich gas stream.

Disclosure of Invention

It is a general object of the present invention to provide an apparatus and method for converting hydrocarbon fuel into a hydrogen rich gas. In an exemplary embodiment of the invention, a compact fuel processor is designed for converting a hydrocarbon fuel feed to a hydrogen rich gas, in which embodiment the fuel processor assembly comprises: a cylindrical body having an inlet end and an outlet end, wherein the cylindrical body contains a plurality of catalysts arranged in tandem to form a plurality of reaction zones in series; a heat exchanger having an inlet end and an outlet end, wherein the heat exchanger passes through the interior of the cylindrical body along the length thereof so as to generate or absorb heat as required by each particular reaction zone. In the exemplary embodiment, the plurality of catalysts includes: autothermal reforming catalysts, desulfurization catalysts, water-gas shift catalysts, preferential oxidation catalysts, and mixtures and combinations of these or similar catalysts. In the exemplary fuel processor, the hydrocarbon fuel feed used is preheated prior to being channeled into the cylinder-preferably by passing through a heat exchanger, or may be heated by a fuel preheater located at an upstream operating location in the autothermal reforming zone. The variety of hydrocarbons that may be used is wide, however, in an exemplary embodiment, the hydrocarbon fuel may be selected from the following: natural gas, gasoline, diesel, fuel oil, propane, liquefied petroleum gas, methanol, ethanol, other suitable and similar hydrocarbons, and mixtures of these fuels.

Those skilled in the art will also understand and appreciate that: other exemplary embodiments of the invention include a compact fuel processor for converting a hydrocarbon fuel feed to a hydrogen rich gas, the fuel processor comprising: a reaction chamber; a plurality of reaction zones are formed in advance in the reaction chamber, wherein each reaction zone is characterized by a chemical reaction occurring in the reaction zone; and a heat exchanger having an inlet end and an outlet end, wherein the heat exchanger is at least partially located within the reaction chamber. In one such exemplary embodiment, a first reaction zone contains an autothermal reforming catalyst; a second reaction zone containing a desulfurization catalyst; a third reaction zone containing a water gas shift catalyst; and a reaction zone module containing a preferential oxidation catalyst. In designing such an exemplary embodiment, it is contemplated that substantially no heat exchanger is disposed within the first reaction zone. The hydrocarbon fuel feed in an exemplary embodiment is preheated by passing it through a heat exchanger before being channeled into the reaction chamber. Alternatively, the mixture of hydrocarbon fuel feed, air and water is preheated by passing through a heat exchanger prior to being introduced into the first reaction zone. A wide range of hydrocarbon fuels, as listed above, may be used.

Those skilled in the art will appreciate that: in a plurality of reaction zonesEach reaction zone of (a) comprises one or more catalysts. In certain such exemplary embodiments, the catalyst is selected from the following classes: autothermal reforming catalysts, desulfurization catalysts, water-gas shift catalysts, preferential oxidation catalysts, and mixtures and compounds of these and other similar catalysts. A permeable plate may be used to separate any particular reaction zone containing more than one catalyst from adjacent reaction zones, wherein the plate may also be used to support adjacent reaction zones. In an exemplary embodiment, the plate member may be selected from: expanded metal, metal screens, wire mesh, sintered metal, porous ceramics, or combinations of these and other similar materials. In an exemplary embodiment, it is preferable that: the plate is at least partially made of INCONEL(registered trademarks related to the use of nickel alloys and inconel), carbon steel, and stainless steel.

The invention also includes a method for converting hydrocarbon fuel to a hydrogen rich gas. An exemplary method employs the apparatus described above. The method generally adopts the following measures: a fuel processor is provided with a reaction chamber having a plurality of catalysts disposed therein. The reaction gas is flowed through the reaction chamber in such a manner that: so that each of the reaction zones forms a plurality of discrete reaction zones. By passing the hydrocarbon fuel through the various reaction zones in sequence in a predetermined manner, a hydrogen-rich gas can be produced in a manner that optimizes space utilization and heat transfer considerations.

Drawings

The following description will be made with reference to the accompanying drawings, in which:

FIG. 1 is a simplified flow diagram illustrating an exemplary embodiment of the present invention;

FIG. 2 illustrates a first exemplary embodiment of a compact fuel processor according to the present invention; and

FIG. 3 illustrates a second exemplary embodiment of a compact fuel processor according to the present invention.

Detailed Description

The present invention generally relates to an apparatus for converting hydrocarbon fuel into a hydrogen rich gas. In a preferred aspect, the apparatus and methods described herein relate to a compact processor for producing a hydrogen-rich gas stream for a fuel cell from a hydrocarbon fuel. However, it is contemplated that the apparatus and methods described herein may be used for other applications, including any application where it is desirable to obtain a hydrogen-rich gas stream. Thus, although the invention described herein is designed for use with fuel cells, the invention is not limited to such applications.

Various exemplary embodiments of the present invention describe a fuel processor or process employing such a fuel processor in which a hydrocarbon fuel feed is directed through the fuel processor. The hydrocarbon fuel may be a liquid or a gas at ambient conditions, so long as it can be vaporized. In the present context, "hydrocarbon" refers to organic compounds having C-H bonds that are capable of generating hydrogen gas by a partial oxidation reaction or a steam reforming reaction. It is not excluded that the molecular structure of the compound contains atoms other than carbon and hydrogen. Thus, fuels suitable for use in the methods and apparatus disclosed herein include, but are not limited to, natural gas, methane, ethane, propane, butane, naphtha, gasoline, diesel, alcohols (e.g., methanol, ethanol, propanol), and the like.

The feed to the fuel processor includes hydrocarbon fuel, oxygen, and water. The oxygen feed may be in the form of air, enriched air, or may also be substantially pure oxygen. The water supplied may be liquid water or may be in the form of water vapor. As will be discussed below, the percentages of the various components in the feed may be determined based on the desired production conditions.

In accordance with the present invention, the gas stream exiting the fuel processor includes hydrogen and carbon dioxide, and may include some moisture, unconverted hydrocarbons, carbon monoxide, impurities (e.g., hydrogen sulfide and ammonia), and inert components (e.g., nitrogen and argon, especially if air components are present in the feed stream).

FIG. 1 is a general flow chart illustrating various process steps in an exemplary embodiment of the invention. Those skilled in the art will appreciate that: a degree of progressive sequencing will be required during the flow of reactants through the reactor described herein.

Process step a is an autothermal reforming process in which two reactions are integrated: partial oxidation (see chemical equation I below), and an optional steam reforming reaction (see chemical equation II below), which are combined to convert feed stream F into a synthesis gas containing hydrogen and carbon dioxide. Chemical reaction formulas I and II are exemplary chemical formulas in which methane is the hydrocarbon:

CH₄+¹/₂O₂→2H₂+CO (I)

CH₄+H₂O→3H₂+CO (II)

the partial oxidation reaction occurs at a very rapid rate so that the conversion of the added oxygen is accomplished and heat is generated. The steam reforming reaction is slow and consumes heat. The higher the concentration of oxygen in the feed gas stream, the more favorable the partial oxidation reaction takes place, while the higher the concentration of steam in the feed, the more favorable the steam reforming. Thus, the ratio of oxygen to hydrocarbon, and the ratio of water to hydrocarbon are two characteristic indicators. These two ratios affect the operating temperature and the hydrogen production.

The operating temperature of the autothermal reforming step is in the range of about 550 c to about 900 c, depending on the feed conditions and the catalyst. The invention employs a catalyst bed comprised of a partial oxidation catalyst with or without a steam reforming catalyst. The catalyst may be in any form including pellets, spheres, extruded shapes, monoliths, and the like. Partial oxidation catalysts are well known to those skilled in the art and are typically made from noble metals such as platinum, palladium, rhodium, and/or ruthenium, which are formed on an alumina coating (washcoat) of a monolith, extruded profile, pellet or other support. Non-noble metals such as nickel, cobalt, etc. may also be used. Titanium oxide, zirconium oxide, silicon oxide and magnesium oxide have been proposed as coating layers in the prior art literature. Numerous other materials that can act as "promoters" for lanthanum, cerium, potassium, etc. have also been mentioned in the technical literature as improving the effectiveness of partial oxidation catalysts.

Steam reforming catalysts are also well known to those skilled in the art and include nickel or noble metals such as platinum, palladium, rhodium, and/or ruthenium with some amount of cobalt. The catalyst may be supported on a single material or a combination of materials such as magnesia, alumina, silica, zirconia, or magnesium aluminate. Alternatively, the steam reforming catalyst may also comprise nickel, preferably supported on a single material or a combination of materials of magnesia, alumina, silica, zirconia, or magnesium aluminate, with an alkali metal such as potassium as its promoter.

Process step B is a cooling step for cooling the syngas stream output from step a to about 200 c to about 600 c, preferably in the range of about 300 c to about 500 c, and more preferably about 375 c to about 425 c, to optimize the syngas exit temperature for further processing. The cooling may be performed using fins, heat pipes or heat exchangers, depending on the design specifications and whether enthalpy is required for the recycle/recycle stream. An exemplary embodiment of step B employs a heat exchanger that utilizes feed stream F circulated through itself as a coolant. The heat exchanger may be designed in any suitable configuration known to those skilled in the art, including shell and tube, plate, spiral, etc., and alternatively, or in addition to the above, the cooling step B may be cooled by additional injection of fuel, air, water, etc. feed components. Among them, the water injection is preferable because it absorbs a large amount of heat during the evaporation of water vapor. The amount of components added depends on the degree of cooling desired and can be readily determined by one skilled in the art.

Step C is a purification step. The main impurity in the hydrocarbon stream is sulfur, which has been converted to hydrogen sulfide in the previous autothermal reforming step a. It is preferable that: the treatment core used in treatment step C comprises zinc oxide and/or other material capable of absorbing and converting hydrogen sulfide and comprises a carrier (e.g., monolith, extruded shape, pellet, etc.). Desulfurization is accomplished by converting hydrogen sulfide to water according to the following chemical reaction formula III:

H₂S+ZnO→H₂O+ZnS (III)

other impurities such as chlorides and the like can also be removed. Preferably, the reaction is carried out at a temperature in the range of about 300 c to about 500 c, and most desirably at a temperature in the range of about 375 c to about 425 c. Zinc oxide has been found to be a very effective hydrogen sulfide absorbent over a wide temperature range of about 25 c to 700 c, and thus, by proper selection of the operating temperature, zinc oxide provides great production flexibility in subsequent processing steps.

The effluent gas stream is then fed to a mixing step D, in which water is optionally added to the gas stream. The added water may lower the temperature of the reactant stream as it evaporates, and the added water may provide more water for the water gas shift reaction that occurs in step E (discussed below). The water vapor and other effluent components are mixed by passing through a treatment core, such as an inert material such as ceramic beads or the like, or other similar material, which effectively mixes and/or facilitates the evaporation of the water. Alternatively, any additional water may be introduced at the time of feeding and the mixing step repositioned to facilitate better mixing of the oxidant gas in the CO oxidation step G as will be described hereinafter.

Process step E is a water gas shift reaction which converts carbon monoxide to carbon dioxide according to the following reaction scheme IV:

H₂O+CO→H₂+CO₂ (IV)

this step is very important because carbon monoxide is not only highly toxic to humans, but also harmful to fuel cells. The concentration of carbon monoxide should be reduced to a level that can be tolerated by the fuel cell and should generally be below 50 ppm. Generally, the temperature at which the water-gas shift reaction occurs ranges from 150 ℃ to 600 ℃, depending on the catalyst used. Under these conditions, most of the carbon monoxide in the gas stream can be converted in this step.

Low temperature type shift catalysts operating at temperatures between about 150 c and 300 c include, for example: copper oxide; copper supported on zirconia and other transition metal oxides; zinc supported on a transition metal oxide or a refractory support such as silica, alumina, zirconia, and the like; or a noble metal such as platinum, rhenium, palladium, rhodium, or gold on a suitable support such as silica, alumina, zirconia, or the like.

The desired operating temperature for high temperature type conversion catalysts is between about 300 c and 600 c, such conversion catalysts include transition metal oxides such as ferric oxide or chromium oxide, and optionally include promoters such as copper or iron silicide. The high temperature type shift catalyst also includes a precious metal on a support, such as platinum, palladium, and/or other platinum group metals on a support.

The processing core for performing this step includes a packed bed of the above-described high temperature shift catalyst or low temperature shift catalyst, which may alternatively be formed of both the high temperature shift catalyst and the low temperature shift catalyst. The temperature at which this step is carried out is any temperature suitable for carrying out the water-gas shift reaction, preferably between about 150 ℃ and 400 ℃, depending on the type of catalyst used. The optional design is: a cooling element such as a cooling coil is provided in the process core of the shift reactor to reduce the reaction temperature in the packed bed of catalyst. The lower the temperature, the more favourable the conversion of carbon monoxide to carbon dioxide. In addition, if the high temperature shift and the low temperature shift are two separate steps, a purification process step C can also be performed between the high temperature shift and the low temperature shift using a desulfurization module located between the high temperature shift step and the low temperature shift step.

The treatment step F' is a cooling step, which in one embodiment is carried out by means of a heat exchanger. The heat exchanger may be of any suitable construction including shell and tube, plate, spiral, etc. Alternatively, heat pipes or other forms of heat sinks may be used. The purpose of the heat exchanger is to reduce the temperature of the gas stream so that the temperature of the effluent is preferably between about 90 c and 150 c.

Oxygen is added during the treatment in step F'. Oxygen will be consumed by the reaction in process step G described below. The oxygen input may be in the form of air, oxygen-enriched air, or substantially pure oxygen. The heat exchanger may be designed to mix air with the hydrogen rich gas. Alternatively, the mixing may be performed using embodiments of step D.

Process step G is an oxidation step in which almost all of the remaining carbon monoxide in the effluent stream is converted to carbon dioxide. The treatment is carried out in the presence of a catalyst for the oxidation of carbon monoxide, which may be in any suitable form, for example in the form of pellets, spheres, monoliths or the like. Oxidation catalysts for the oxidation of carbon monoxide are well known and such catalysts generally comprise a noble metal (e.g. platinum, palladium, etc.) and/or a transition metal (e.g. iron, cobalt, manganese, etc.) and/or a compound of a noble metal or transition metal-especially an oxide of such metals. One preferred oxidation catalyst is platinum on an alumina coating. The coating may be applied to a monolith, extruded profile, pellet, or other form of support. Other materials such as cerium or lanthanum may be additionally added to promote the catalyst performance. In the prior art literature, a number of other formulations have been proposed by some practitioners and claimed to perform better than rhodium catalysts or alumina catalysts. Other materials such as ruthenium, palladium, gold, etc. are also mentioned in the literature as being effective for the above-mentioned applications.

In step G, the following two reactions occur: the desired oxidation of carbon monoxide (equation V), and the undesired oxidation of hydrogen (equation VI), are the two reactions:

CO+¹/₂O₂→CO₂ (V)

H₂+¹/₂O₂→H₂O (VI)

the low temperature conditions will favor preferential oxidation of carbon monoxide, and since both reactions are exothermic, it would be advantageous to have a cooling element such as a cooling coil in the process step. The operating temperature of the process is preferably maintained in the approximate range of 90 c to 150 c. Preferably, process step G reduces the carbon monoxide concentration to a level of less than 50ppm, which is suitable for the environment in which the fuel cell is used, but one skilled in the art will appreciate that: the invention can also be designed to produce hydrogen-rich gas with higher or lower carbon monoxide levels.

The effluent from the fuel processor is a hydrogen-rich gas P that contains carbon dioxide and other components such as water, inert components (e.g., nitrogen, argon), residual hydrocarbons, etc. The gaseous product may be used as a feedstock for a fuel cell or in other applications where a hydrogen-rich gas stream is desired. The optional scheme is as follows: the gaseous product may be sent to another process, for example for removal of carbon dioxide, water or other components therefrom.

Fig. 2 illustrates a cross-sectional view of a fuel processor 20, which is an exemplary embodiment of the present invention. Those of ordinary skill in the art will understand and appreciate that: fuel, or alternatively a fuel/oxygen mixture, or alternatively a fuel/oxygen/water mixture 200 is channeled to the inlet end of a coil heat exchanger 202. The heat exchanger is disposed within the fuel processor such that the heat exchanger extends substantially along the length of the fuel processor. The heat exchanger preheats the fuel and cools/controls the temperature of each reaction zone. Those skilled in the art will appreciate that: heat exchange may be affected by a number of factors including the flow rate of the fuel, the heat capacity of the fuel, the number of coils in any particular reaction zone, the diameter of the tubes from which the coils are made, whether the coils are finned, and the like. However, the heat exchange design can be optimized by routine calculation and experimentation. After leaving the heat exchanger, the preheated fuel flows through a reactor feed pipe 204 to a first reaction zone 208. The reactor feed line may be provided with flow control devices and other similar devices for adjusting and optimizing the fuel mixture prior to its entry into the first reaction zone 208. The first reaction zone 208 in the exemplary embodiment is filled with an autothermal reforming reaction catalyst. The catalyst may be in the form of pellets, or supported on a monolith. In some instances, it may be desirable to provide a distribution plate 206 to distribute the fuel evenly throughout the first reaction zone. Furthermore, such alternative designs may also be employed: an electric preheater (not shown) is used to start the fuel processor. After the fuel has reached the first reaction zone, thereby enabling the formation of a hydrogen rich gas, the gas can naturally flow into the second reaction zone 210 due to the hydrogen rich gas pressure. In the exemplary embodiment, the second reaction zone is packed with a desulfurization catalyst, which is preferably zinc oxide. After the hydrogen-rich gas passes through a desulfurization catalyst, such as zinc oxide, the concentration of sulfur-containing compounds in the gas stream is significantly reduced. The desulfurized hydrogen-rich gas then flows into third reaction zone 212. The third reaction zone in this exemplary embodiment is packed with a water gas shift catalyst, or a mixture of such catalysts as described above. After passing through the catalyst, the hydrogen content of the hydrogen-rich gas is further increased, while the carbon monoxide content is reduced. The hydrogen-rich gas then flows to fourth reaction zone 214, which contains a preferential oxidation catalyst therein. As discussed above, the catalyst is preferably capable of reducing the concentration of carbon monoxide to less than 50 ppm. In some examples, air or other suitable oxygen-derived oxidizing gas may be injected into the fourth reaction zone to facilitate optimization of the preferential oxidation reaction. The injection process may be carried out by known means, such as a simple gas injection tube (not shown) inserted into the bed of partial oxidation catalyst. In a preferred embodiment, the preferential oxidation reaction zone is constructed substantially in the form of a perforated tube designed to provide a uniform distribution of injected oxygen. The final product is a hydrogen rich gas 216. It should also be noted that: in a preferred exemplary embodiment, inert, but perforated, flexible materials such as glass wool, ceramic wool, rock wool, or other similar inert materials may be used in the transition region 218 between the reaction zones. The material has the functions of: facilitates filling of the reaction zones with various catalysts, helps prevent inadvertent mixing of catalysts during transport, and creates a transition or buffer zone between various reaction zones. It is obvious to the person skilled in the art that: the produced hydrogen-rich gas is preferably used in a fuel cell, but may also be stored or used in other processes.

Those skilled in the art will understand and see, after reading the description of FIG. 2 above: each module can perform a function independently. Feed stream F (200) is introduced through an inlet tube (not shown) and gaseous product P216 is drawn out through an outlet tube (not shown). Reaction zone 208 is an autothermal reforming reaction zone corresponding to step a in figure 1. An electric heater (not shown) may optionally be provided at the bottom inlet of the reactor for providing heat during start-up. Reaction zone 210 is a purification reaction zone corresponding to process step C in fig. 1. Reaction zone 212 corresponds to process step E of fig. 1 and is a water-gas shift reaction zone. The cooling operation corresponding to process step F' in fig. 1 is performed by heat exchanger 202. Reaction zone 214 is used to perform an oxidation operation corresponding to process step G in fig. 1. A source of air (not shown) is used as a source of oxygen to provide process gas for the oxidation reaction (see equation V) in reaction zone 214. Reaction zone 214 also includes a heat exchanger 202 disposed in or around the catalyst bed for maintaining the temperature of the oxidation reaction at a desired value, as will be appreciated by those skilled in the art: the above-described process configuration in this embodiment can be modified based on a number of factors including, but not limited to, feedstock quality and desired product quality.

Referring now to fig. 3, a second exemplary embodiment of the present invention is shown in cross-section of a fuel processor reactor chamber 40. Those of ordinary skill in the art will understand and appreciate that: fuel, or alternatively a fuel/oxygen mixture, or alternatively a fuel/oxygen/water mixture 300 is channeled to the inlet end of a first coil heat exchanger 302. A plurality of heat exchangers (302, 304, and 306) are provided, which are preferably in communication with each other. Each heat exchanger is disposed within the fuel processor such that each heat exchanger extends substantially the length of a particular reaction zone. The heat exchanger preheats the fuel and cools/controls the temperature of each reaction zone. Those skilled in the art will appreciate that: heat exchange may be affected by a number of factors including the flow rate of the fuel, the heat capacity of the fuel, the number of coils in any particular reaction zone, the diameter of the tubes from which the coils are made, whether the coils are finned, and the like. However, the heat exchange design can be optimized by routine calculation and experimentation. After leaving the heat exchanger, the preheated fuel flows through a reactor feed pipe 308 to the first reaction zone 312. The reactor feed line may be provided with flow control devices and other similar devices for adjusting and optimizing the fuel mixture prior to its entry into the first reaction zone 312. The first reaction zone 312 in this exemplary embodiment is filled with an autothermal reforming reaction catalyst. The catalyst may be in the form of pellets, or supported on a monolith. In some instances, it may be desirable to provide a distribution plate 310 to distribute the fuel evenly throughout the first reaction zone. In addition, such a design may be selected: an electric preheater (not shown) is used to start the fuel processor. After the fuel has reached the first reaction zone, thereby enabling the formation of a hydrogen rich gas, the gas can naturally flow through the first support plate 314, due to the pressure, and thus into the second reaction zone 316. In the exemplary embodiment, the second reaction zone is packed with a desulfurization catalyst, which is preferably zinc oxide. The concentration of sulfur-containing compounds in the gas stream is significantly reduced after the hydrogen-rich gas has passed over a desulfurization catalyst, such as zinc oxide. The temperature in the second reaction zone is controlled at least in part by the third heat exchanger 306. The desulfurized hydrogen-rich gas then flows through the second support plate 318 into the third reaction zone 320. The third reaction zone in this exemplary embodiment is packed with a water gas shift catalyst, or a mixture of such catalysts as described above. After passing through the catalyst, the hydrogen content of the hydrogen-rich gas is further increased, while the carbon monoxide content is reduced. The temperature in the third reaction zone is controlled, at least in part, by the second heat exchanger 304. The hydrogen-rich gas then flows through the third support plate 322 into the fourth reaction zone 324, which contains the preferential oxidation catalyst. As discussed above, the catalyst can reduce the concentration of carbon monoxide to less than 50 ppm. In some examples, air or other suitable oxygen-derived oxidizing gas may be injected into the fourth reaction zone to facilitate optimization of the preferential oxidation reaction. The injection process may be carried out by known means, such as a simple gas injection tube (not shown) inserted into the bed of partial oxidation catalyst. In a preferred embodiment, the preferential oxidation reaction zone is constructed to substantially include a perforated tube configured to provide a uniform distribution of injected oxygen. The temperature in the fourth reaction zone is controlled at least in part by the first heat exchanger 302 which, while preheating the incoming fuel, also cools the final gaseous product to be discharged from the reaction zone. The final product is a hydrogen rich gas 326. It should also be noted that: the individual reaction zones in this exemplary embodiment are separated from one another by inert, but perforated, support plates. The support plate is preferably rigid and chemically inert under the conditions used as reactor material in the transition zone between the reactors. The material has the functions of: facilitates filling of the reaction zones with various catalysts, helps prevent inadvertent mixing of catalysts during transport, and creates a transition or buffer zone between various reaction zones. It is obvious to the person skilled in the art that: the produced hydrogen-rich gas is preferably used in a fuel cell, but may also be stored or used in other processes.

Those skilled in the art will understand and see, after reading the description of FIG. 3 above: each module can perform a function independently. Feed stream F (300) is introduced through an inlet tube (not shown) and gaseous product P326 is drawn out through an outlet tube (not shown). The reaction zone 312 is an autothermal reforming reaction zone corresponding to process step a in figure 1. An electric heater (not shown) may optionally be provided at the bottom inlet of the reactor for providing heat during start-up. Reaction zone 316 is a purification reaction zone corresponding to process step C in fig. 1. Reaction zone 320 corresponds to process step E of fig. 1 and is a water-gas shift reaction zone. The cooling operation corresponding to process step F' in fig. 1 is performed by heat exchanger 304. The reaction zone 324 is used to perform an oxidation operation corresponding to process step G in fig. 1. A source of air (not shown) is used as the source of oxygen to provide process gas for the oxidation reaction (see equation V) in the reaction zone 324. The reaction zone 324 also includes a heat exchanger 302 disposed in or around the catalyst bed for maintaining the temperature of the oxidation reaction at a desired value, as will be appreciated by those skilled in the art: the above-described process configuration in this embodiment can be modified based on a number of factors including, but not limited to, feedstock quality and desired product quality.

In view of the above disclosure, those of ordinary skill in the art will understand and appreciate that: the present invention may be implemented in a wide variety of possible embodiments, depending on design criteria. One exemplary embodiment thereof includes a compact fuel processor for converting a hydrocarbon fuel feed to a hydrogen rich gas, in which the fuel processor assembly includes: a cylindrical body having an inlet end and an outlet end, wherein the cylindrical body contains a plurality of catalysts arranged in tandem to form a plurality of reaction zones in series; a heat exchanger having an inlet end and an outlet end, wherein the heat exchanger passes through the interior of the cylindrical body along the length thereof so as to generate or absorb heat as required by each particular reaction zone. In the exemplary embodiment, the plurality of catalysts includes: autothermal reforming catalysts, desulfurization catalysts, water-gas shift catalysts, preferential oxidation catalysts, and mixtures and combinations of these or similar catalysts. In a preferred exemplary embodiment, the heat exchanger is not disposed in the autothermal reforming catalyst. In the exemplary fuel processor, the hydrocarbon fuel feed used is preheated, preferably by passing through a heat exchanger, prior to being channeled into the cylinder, or may be heated by a fuel preheater located at an upstream operating location in the autothermal reforming zone. The range of hydrocarbon types that can be used is wide, however, in an exemplary embodiment, the hydrocarbon fuel is selected from the following: natural gas, gasoline, diesel, fuel oil, propane, liquefied petroleum gas, methanol, ethanol, other suitable and similar hydrocarbons, and mixtures of these fuels. In an exemplary embodiment, the preferred design is: the orientation of the cylinder is substantially vertical with the outlet end at the top and the flow of reactants is substantially upward from the inlet end to the outlet end.

Those skilled in the art will also understand and appreciate that: another exemplary embodiment of the present invention includes a compact fuel processor for converting a hydrocarbon fuel feed into a hydrogen rich gas, the fuel processor comprising: a reaction chamber; a plurality of reaction zones are formed in advance in the reaction chamber, wherein each reaction zone is characterized by a chemical reaction occurring in the reaction zone; and a heat exchanger having an inlet end and an outlet end, wherein the heat exchanger is at least partially located within the reaction chamber. In one such exemplary embodiment, a first reaction zone contains an autothermal reforming catalyst; a second reaction zone containing a desulfurization catalyst; a third reaction zone containing a water gas shift catalyst; and a reaction zone module containing a preferential oxidation catalyst. In designing such an exemplary embodiment, it is contemplated that substantially no heat exchanger is disposed within the first reaction zone. In certain exemplary embodiments, the hydrocarbon fuel feed is preheated by passing it through a heat exchanger before being channeled into the reaction chamber. Alternatively, the mixture of hydrocarbon fuel feed, air and water is preheated by passing through a heat exchanger prior to being introduced into the first reaction zone. The range of hydrocarbon types that can be used is wide, however, in an exemplary embodiment, the hydrocarbon fuel is selected from the following: natural gas, gasoline, diesel, fuel oil, propane, liquefied petroleum gas, methanol, ethanol, other suitable and similar hydrocarbons, and mixtures of these fuels. In an exemplary embodiment, the inlet end of the heat exchanger is located in the fourth reaction zone and the outlet end is located in the second reaction zone.

Those skilled in the art will appreciate that: each of the plurality of reaction zones comprises one or more catalysts. In certain such exemplary embodiments, the catalyst is selected from the following classes: autothermal reforming catalysts, desulfurization catalysts, water-gas shift catalysts, preferential oxidation catalysts, and mixtures and compounds of these and other similar catalysts. Any particular reaction zone containing more than one catalyst may be separated from adjacent reaction zones by a permeable plate which is also used to support adjacent reaction zones. In an exemplary embodiment, the plate member may be selected from: expanded metal, metal screens, wire mesh, sintered metal, porous ceramics, or combinations of these and other similar materials. In an exemplary embodiment, it is preferable that: the plate is at least partially made of INCONEL(registered trademarks related to the use of nickel alloys and inconel), carbon steel, and stainless steel.

While the apparatus, compositions and methods of the present invention have been described above in terms of preferred or exemplary embodiments, it will be apparent to those of skill in the art that: changes may be made in the processing methods described herein without departing from the spirit and scope of the invention. All such substitutions and modifications apparent to those skilled in the art are deemed to be within the spirit and scope of the invention as defined by the appended claims.

Claims (14)

1. A compact fuel processor for converting a hydrocarbon fuel feed into a hydrogen rich gas, comprising:

a cylindrical body having an inlet end and an outlet end, wherein the cylindrical body contains a plurality of catalysts arranged in tandem to form a plurality of reaction zones in series; the plurality of catalysts comprises an autothermal reforming catalyst contained in a first reaction zone;

a heat exchanger having an inlet end and an outlet end, wherein said heat exchanger passes through the length of said cylinder from the interior thereof for generating or absorbing heat as required by a particular reaction zone, characterized by: the heat exchanger is not disposed in the autothermal reforming catalyst; and

a reactor feed for directing preheated fuel from said heat exchanger to said first reaction zone.

2. The compact fuel processor of claim 1, wherein: the plurality of catalysts includes a desulfurization catalyst, a water gas shift catalyst, or a preferential oxidation catalyst.

3. The compact fuel processor of claim 2, wherein: the hydrocarbon fuel feed is preheated by passing through the heat exchanger before being directed into the cylinder.

4. The compact fuel processor of claim 2, wherein: the hydrocarbon fuel is selected from the group of fuels consisting of: natural gas, gasoline, diesel, fuel oil, propane, liquefied petroleum gas, methanol, ethanol, and mixtures of these fuels.

5. The compact fuel processor of claim 1, wherein: the inlet end of the heat exchanger is located at the outlet end of the cylinder.

6. The compact fuel processor of claim 1, wherein: the cylinder is oriented substantially vertically with its outlet end at the top.

7. A compact fuel processor for converting a hydrocarbon fuel feed into a hydrogen rich gas, the fuel processor comprising:

a reaction chamber;

a plurality of reaction zones preformed within the reaction chamber, each reaction zone characterized by a chemical reaction occurring within the reaction zone, and a first reaction zone containing an autothermal reforming catalyst;

a heat exchanger having an inlet end and an outlet end, wherein the heat exchanger is disposed in the reaction chamber, the heat exchanger not being disposed in the first reaction zone; and

a reactor feed for directing preheated fuel from said heat exchanger to said first reaction zone.

8. The compact fuel processor of claim 7, wherein: a second reaction zone containing a desulfurization catalyst; a third reaction zone containing a water gas shift catalyst; and a fourth reaction zone containing a preferential oxidation catalyst.

9. The compact fuel processor of claim 7, wherein: the hydrocarbon fuel feed is preheated by flowing through the heat exchanger prior to being directed into the reaction chamber.

10. The compact fuel processor of claim 7, wherein: the mixture of hydrocarbon fuel feed, air and water is preheated by passing through the heat exchanger prior to being directed into the first reaction zone.

11. The compact fuel processor of claim 8, wherein: the inlet end of the heat exchanger is located in the fourth reaction zone and the outlet end is located in the second reaction zone.

12. The compact fuel processor of claim 7, wherein: each of the plurality of reaction zones contains one or more catalysts selected from the group consisting of: autothermal reforming catalysts, desulfurization catalysts, water-gas shift catalysts, and preferential oxidation catalysts.

13. The compact fuel processor of claim 12, wherein: a reaction zone containing more than one catalyst is separated from adjacent reaction zones by a permeable plate and supported by the plate.

14. The compact fuel processor of claim 13, wherein: the plate member is selected from the group consisting of: porous metal plates, metal screens, wire mesh, sintered metals, and porous ceramics.