CN201058854Y - A fixed bed device for Fischer-Tropsch synthesis - Google Patents

Abstract

The utility model provides a fixed bed device for producing liquid hydrocarbons by Fischer-Tropsch synthesis, which comprises: a heater, a reactor connected to the upper part of the heater, and a casing sleeved outside the reactor and connected with the heater , wherein, the heater is provided with a heating medium flue gas pipeline, the inlet of the flue gas pipeline is opened on the upper part of the heater, and the outlet of the flue gas pipeline is opened on the lower part of the heater, through the flue gas pipeline will enter The circulating water in the heater is heated, and the inlet and outlet of the circulating water are respectively set on the wall of the heater, and the outlet of the circulating water is set on the upper part of the heater and communicates with the casing outside the reactor; the heater A raw material gas pipeline is arranged inside, a raw material gas inlet and a raw material gas outlet are arranged on the wall of the heater, and the raw material gas outlet communicates with the reactor. This fixed-bed device for Fischer-Tropsch synthesis can effectively solve the problem of excessive reaction heat in Fischer-Tropsch synthesis, ensure sufficient reaction of raw material gas, and improve the conversion rate of Fischer-Tropsch synthesis reaction.

Description

A fixed bed device for Fischer-Tropsch synthesis

technical field

The utility model provides a fixed bed device, which is a device for Fischer-Tropsch synthesis reaction, especially refers to the use of an improved fixed bed that can fully convert synthesis gas into liquid hydrocarbons through Fischer-Tropsch synthesis reaction. device.

Background technique

Due to the increasing shortage and poor quality of petroleum resources, the increasing demand for refined oil products, and the increasingly stringent environmental regulations, obtaining high-quality liquid refined oil fuels through new methods is a major problem facing China and the world. Fischer-Tropsch synthesis is the process of using _H2 and CO as the main components to synthesize hydrocarbons under the action of a catalyst. It is a new way to produce liquid fuels and is currently the most effective and promising technology. It can be used in various processing processes such as coal to oil, natural gas to oil, etc.

According to different catalysts, Fischer-Tropsch synthesis reactors can have various forms, such as fixed bed, gas-solid fluidized bed and slurry bed, etc. Among them, the operation of gas-solid fluidized bed is complicated and easy to deposit carbon, so it is less used now. Slurry bed has the advantages of good heat transfer effect and easy control of reaction temperature, and is the mainstream of Fischer-Tropsch synthesis reactor development. However, the single-pass conversion rate of the slurry bed reactor is low, and solid-liquid separation is difficult, so it is only suitable for large-scale synthetic oil plants. The fixed bed has the characteristics of simple operation and flexible and diverse forms, which is very attractive to many small and medium-sized synthetic oil plants, but the poor heat transfer performance of the fixed bed is an important factor restricting its development.

The traditional fixed-bed device for Fischer-Tropsch synthesis adopts the feeding method of gas from top to bottom, and the heat exchange medium circulates countercurrently in the casing from bottom to top. This heat exchange method cannot effectively remove a large amount of reaction heat released at the front end of the catalyst bed quickly, which may easily lead to "flying temperature" of the reactor, reduce the selectivity of the target product, and easily form carbon deposits. Moreover, the single-pass gas conversion rate of the fixed-bed device is not high, and the exhaust gas circulation needs to be carried out by the power device, which increases the operating cost of the device.

Utility model content

The utility model provides a novel fixed bed device for Fischer-Tropsch synthesis reaction. The device can effectively remove reaction heat, avoid reaction hot spots and overheating phenomena, and maintain the temperature of the entire reaction system in a "constant temperature range" to ensure To ensure the smooth progress of the reaction, and through the implementation of multiple reactor operations, the single-pass conversion rate of the synthesis gas is greatly improved, so that the tail gas does not need to be recycled.

The purpose of this utility model is to provide a fixed bed device for Fischer-Tropsch synthesis reaction, by means of this novel fixed bed device, the synthesis gas (raw material gas) enters the catalyst bed of the reactor from the bottom of the fixed bed to undergo a Fischer-Tropsch synthesis reaction , the circulating water is passed into the casing outside the reactor, and the circulating water absorbs heat in the lower part of the reactor and releases heat in the upper part, thereby maintaining a constant temperature in the reactor, that is, ensuring a constant temperature of the catalyst layer reaction in the reactor, and eliminating The method of the utility model is especially suitable for the simple and convenient production process of liquid hydrocarbons on a small and medium scale due to the occurrence of runaway temperature.

The purpose of this utility model can be achieved through the following technical solutions.

The utility model provides a fixed bed device for Fischer-Tropsch synthesis reaction, which is characterized in that: the fixed bed device is at least composed of two groups of fixed beds connected end to end in series, each group of fixed beds includes a reactor, and the The reactor corresponds to a heater connected to the heater, a sleeve connected to the heater, a heat exchanger (also called a condenser) and a three-phase separator, wherein each set of fixed-bed heaters is equipped with a raw material Gas pipeline and heating medium pipeline, the wall of the heater is provided with a raw material gas inlet and a raw material gas outlet, and the raw material gas outlet is connected with the group of reactors, and the heater wall is also provided with a heating medium inlet and a heating medium outlet , and the circulating water inlet and the circulating water outlet of the heater, the circulating water outlet of each set of heaters communicates with the set of casing pipes, and the two sets of reactors connected in series are sequentially connected with heat exchangers and three phase separator.

The above reactor is also equipped with a catalyst inside, so the inside of the reactor can also be referred to as a catalyst bed.

In the utility model, the Fischer-Tropsch synthesis reaction occurs by making the raw material gas enter the catalyst bed from the bottom of the reactor, and feed circulating water into the sleeve outside the reactor (the space between the outer wall of the reactor and the inner wall of the sleeve), The running direction of the circulating water in the casing is the same as that of the raw material gas in the reactor (from bottom to top), that is, the circulating water absorbs heat in the lower part of the reactor and releases heat in the upper part, thereby maintaining the constant temperature of the reactor. The occurrence of runaway temperature is prevented, and the single-pass conversion rate of syngas is improved.

Above-mentioned fixed bed device of the present utility model, by means of two groups or more than two groups of fixed beds end-to-end series connection, wherein each group of fixed beds all comprises the reactor that is used to take place Fischer-Tropsch synthesis reaction, is used for heating circulating water and reaction gas ( Raw material gas) heaters, casings for circulating water flow and heat exchange, wherein the bottom of each group of casings is connected and communicated with the group of heaters, and each group of casings are connected up and down to maintain The temperature and pressure are balanced, so that when the raw material gas passes through the reactor, it can react under the action of the catalyst. Two or more groups of reactors are connected in series, so that the unreacted raw material gas in the first group of reactors can continue to enter the next one. The synthesis reaction continues in the group reactor to achieve the purpose of full reaction.

In the above-mentioned fixed bed device of the present utility model, the bottom of each group of reactors is preferably connected successively with a product collector and a product tank, and the product collector is used to collect the reaction generated in the reactor. The liquid product whose boiling point is higher than the reaction temperature, the product tank is used to collect the product transported from the product collector, and the product is preferably a product processed under reduced pressure.

In a preferred embodiment of the present utility model, the top of each group of reactors is sequentially connected in series with a heat exchanger (condenser) with condensation function and a three-phase separator with separation function, so that the reaction generated After the product flows through the heat exchanger and the three-phase separator, it is first condensed to sieve out the liquid hydrocarbon products (the heat exchanger is used to condense the reaction generated in the reactor and flows out from the top of the reactor with a lower boiling point) Hydrocarbons and water) and unconverted synthesis gas, and then in the three-phase separator, the above-mentioned hydrocarbons with lower boiling point, water and unconverted synthesis gas are separated into water phase, oil phase and gas phase, and the oil phase is passed through After decompression, it can be sent to the product tank as a low-temperature condensed product. The water phase can be rectified and recovered after decompression, and the gas phase enters the next group of reactors to continue the reaction, so that the reaction of the raw material gas is more complete. After the tail gas of the last group of reactors is separated, it is directly vented or burned to use its energy, and the reaction is no longer continued.

In order to heat the circulating water circulating in the heater, the heater of the fixed bed device of the present invention can adopt any known heating method. In a preferred embodiment of the present utility model, what the heating medium of the heater adopts is flue gas , that is, the heating medium pipeline provided inside the heater of the above-mentioned fixed bed device is preferably a flue gas pipeline, the heating medium inlet provided on the wall of the heater is preferably a flue gas inlet, and the heating medium outlet is preferably a flue gas duct The gas outlet, the flue gas inlet is preferably at the upper part of the heater, and the flue gas outlet is at the lower part, which is used to heat the circulating water running inside the heater to a predetermined temperature.

In order to realize the circulation of the circulating water in the fixed bed device of the present utility model, the circulating water runs in the casing and flows out, and the circulating water outlet of the casing is also connected (or extended) with a water storage tank for storing The circulating water flowing out of the sleeve can adjust the temperature, pressure and liquid level of the circulating water in a timely manner by the water storage tank. The water storage tank is also preferably provided with a liquid level gauge and/or an inlet and outlet valve, and more preferably also provided with an explosion-proof valve to monitor the water level and eliminate in time the safety hazard of excessive water pressure rise due to excessive heat absorption. Hidden danger.

In the fixed bed device of the present utility model, the lower end of the water storage tank is provided with a circulation pipeline connected with the circulating water inlet on the wall of the heater. , the temperature drops after heat exchange with the outside world, and then flows down from the external circulation pipeline due to gravity or the action of the circulation pump to re-enter the bottom of the casing to start circulation. The circulation pipeline can be divided into a self-heating circulation pipeline and/or a high-pressure pump forced circulation. The high-pressure pump circulation pipeline is provided with a high-pressure circulation pump on the pipeline so as to realize circulation under high pressure.

In a preferred embodiment of the present utility model, the raw material gas pipeline and the heating medium pipeline in the heater are preferably spiral pipelines, the purpose is to increase the area of heat transfer and heat exchange, and the heating medium pipeline (flue gas pipeline) is more preferably It is a spiral upward pipe.

The utility model utilizes above-mentioned fixed bed device to carry out the method for Fischer-Tropsch synthesis comprising the following steps:

The fresh synthesis gas (raw material gas) with H ₂ and CO as the main components (H ₂ /CO ratio is 0.5-5.0) enters the heater set at the bottom of the fixed bed device, flows in the raw gas pipeline, and is heated by the hot circulating water After being heated to a suitable preheating temperature, the synthesis gas enters and passes through the catalyst bed layer of the fixed bed device in a feed-in manner from bottom to top to undergo a Fischer-Tropsch synthesis reaction, and is connected with the sleeve pipe arranged outside the fixed bed device The circulating water running from bottom to top in the middle is subjected to indirect heat exchange, preferably at a reaction temperature of 180-350°C, a pressure of 1.0-5.0MPa and an operating linear velocity of 0.02-3.2m/s; in this method, The predetermined heating temperature of the circulating water is preferably 10-20° C. lower than the reaction temperature of the Fischer-Tropsch synthesis reaction.

In order to achieve the purpose and effect of the present utility model, in a preferred embodiment of the present utility model, the above-mentioned fixed bed device is formed by at least two groups of fixed beds (head and tail) connected in series; the bottom of the reactor of each group of fixed beds is also provided with Product collector and product tank. The top of the reactor is connected with a heat exchanger (condensation) and a three-phase separator. In this reactor, the liquid product with a boiling point higher than the reaction temperature will flow into the reactor by its own gravity. The product collector, after decompression, is sent to the product tank; and the generated hydrocarbons and water with lower boiling points, which are gaseous at the reaction temperature, will flow out of the reactor from the top of the reactor together with the unconverted synthesis gas , after being condensed by the heat exchanger, it is sent to the three-phase separator for the purpose of separating the water phase, the oil phase and the gas phase, wherein the oil phase is decompressed and sent to the product as a low-temperature condensed product tank, the water phase is decompressed and recovered by rectification, and the gas phase enters the next set of reactors to continue the reaction.

The bottom of each group of reactors is connected with the corresponding set of heaters, which can heat the circulating water, so that the circulating water rises into the casing to exchange heat with the synthesis gas going up in the reactor; at the upper part of the casing structure Also connected with a water storage tank, the temperature, pressure and liquid level of the circulating water can be adjusted in time by the water storage tank; a catalyst (the catalyst layer can also be called a catalyst bed layer) is installed inside the reactor ), the catalyst can be cobalt-based, iron-based or other Fischer-Tropsch synthesis catalysts, and the catalyst used should meet the requirements of stable activity and selectivity and not easily broken in the long-term continuous operation cycle. The outside can also preferably be provided with a heat preservation or heating device, which plays the role of temperature regulation.

As far as this field is concerned, for a strong exothermic reaction carried out in a fixed-bed reactor, when the initial conditions reach or exceed a certain limit, the heat generated by the reaction far exceeds the heat that the system can discharge, and a large amount of instantaneous heat accumulation occurs , the thermal imbalance worsens, causing the temperature of the reaction system to increase by leaps and bounds, leading to the loss of control of the entire system. This phenomenon is called runaway temperature. The temperature runaway has adverse effects on the conversion rate, selectivity, activity and life of the catalyst, etc. of the reaction.

In order to improve the conversion rate and selectivity of the Fischer-Tropsch reaction, the fixed bed device of the present invention is preferably composed of at least two sets of reactors connected in series.

In the technical solution of the utility model, the concentration of the raw material synthesis gas (raw material gas) at the entrance of the catalyst bed is relatively large, and the reaction is relatively violent under the action of the catalyst, and a large amount of heat is released, and the temperature of the bed rises rapidly. The bed temperature reaches the maximum at 1-2m. At a higher temperature, the reaction is accelerated, and the heat release per unit time is also increased. At this time, if the reaction heat cannot be removed in time, there is a danger of "flying temperature" of the bed. In the reactor utilized in the utility model, circulating water is housed in the casing, and the water temperature of the circulating water is heated to 10-20°C lower than the reaction temperature with high-temperature flue gas in the heater at the bottom of the device, and then the circulating water and gas It flows through the reactor casing from bottom to top, and starts to exchange heat with the reactor near the position where the raw material gas just contacts with the catalyst to start the reaction, and a large amount of reaction heat is taken out of the catalyst bed to ensure that the catalyst bed maintains at the synthesis reaction temperature. The temperature of the circulating water after absorbing heat rises and partly vaporizes. Because as the concentration of raw material syngas decreases, the heat release of the reaction gradually decreases, so that the temperature of the catalyst bed is lower than the optimum reaction temperature due to the heat dissipation of the reactor in the upper part of the catalyst bed, which is not conducive to the synthesis gas. Continue the reaction; at this time, the circulating water at a higher temperature in the circulating pipe transfers heat to the catalyst bed to ensure that the remaining unconverted synthesis gas continues to react, and the circulating water rises to the (vapor-liquid) water storage tank at the top of the casing In the process, the temperature drops after heat exchange with the outside world, and then flows down from the external circulation pipeline due to gravity (or under the action of a high-pressure pump) to re-enter the bottom of the casing to start a new cycle.

During the whole process of the Fischer-Tropsch reaction of the utility model, the catalyst bed temperature of the reactor is always maintained in the "constant temperature range", which ensures the smooth progress of the reaction, improves the conversion rate of the synthesis gas, and makes the single-pass conversion rate of the synthesis gas reach More than 80%. The circulating water flows very fast due to the action of gravity, which can quickly take away the heat of reaction and effectively supplement the low-temperature zone. The temperature difference of the water does not exceed 4°C, which ensures the smooth progress of heat exchange and improves the efficiency of the entire reactor. efficiency.

In the utility model, the gas coming out from the top of the last group of reactors includes unreacted raw material gas and light hydrocarbon products, and its temperature is still very high. phase separator. Among them, very few low-carbon hydrocarbons ( _CH4, etc.) and a small part of unreacted raw material gas are vented through the tail gas valve or used as heating fuel. The liquid phase from the separator includes liquid hydrocarbons and generated water. The liquid hydrocarbons enter the product collector, and after decompression, they are sent to the product tank unit for further processing. The water phase is sent to rectification to recover oxygenated organics in the water. The heavy hydrocarbons generated in the reaction with a boiling point higher than the reaction temperature enter the product collector due to their own gravity, and after decompression, they are sent to the product tank unit for subsequent deep processing.

Because the utility model is provided with circulating water in the casing of the reactor, the heater at the bottom of the device can heat the water to a temperature 10-20°C lower than the reaction temperature, and then the circulating water and the raw material gas (synthesis gas) The flow passes through the reactor casing and the catalyst bed respectively from bottom to top. At the beginning of the reaction, the circulating water with a slightly lower temperature is used to absorb the huge heat released by the reaction, and the temperature of the hot spot is lowered so that the phenomenon of "flying temperature" does not occur. The temperature of the water rises and it partially vaporizes. As the reaction proceeds, the gas concentration decreases, the heat release decreases, and the temperature drops. In the upper part of the reactor, the high-temperature circulating water supplements the heat of the reactor bed, so that the unreacted synthesis gas continues to react, and the circulating water rises to In the water storage tank at the top of the casing, the temperature drops after heat exchange with the outside world, and then flows down from the external pipeline due to gravity or the action of the high-pressure circulation pump to re-enter the bottom of the casing to start circulation. The upper and lower temperatures of the entire reactor are controlled in the "constant temperature range", which ensures the smooth progress of the reaction and improves the conversion rate.

The advantage of setting two sets of fixed beds in series is that part of the liquid hydrocarbons produced in the first group of reactors come out of the top of the reactor together with the gas, and enter the heat exchanger to condense and remove the liquid hydrocarbon products; the separated gas enters the The second group of reactors continues to react under the same conditions as the first group of reactors, and then condenses and removes liquid hydrocarbon products again to fully react the raw material gas and vent the tail gas. When the reactor is composed of multiple sets of reactors connected in series, the tail gas can also enter the reactors after the second set, such as the third set of reactors, until the synthesis gas conversion rate reaches a higher ideal level.

The utility model can achieve the effect that the upper and lower temperatures of the whole reactor are controlled in a "constant temperature range", which ensures the smooth progress of the Fischer-Tropsch reaction and improves the conversion rate.

Description of drawings

Fig. 1: Structural diagram of Fischer-Tropsch synthesis single-tube reactor of the present invention.

Fig. 2: A fixed bed device for Fischer-Tropsch synthesis reaction composed of two groups of single-tube reactors of the present invention.

Fig. 3: A fixed-bed device for Fischer-Tropsch synthesis reaction composed of two sets of multi-tube reactors of the present invention.

Figure number:

1--heater 2--high pressure circulation pump 3--catalyst bed

4--reactor 5--casing 6--casing wall

7--Water storage tank 8--Liquid level gauge 9--In and out valve

10--Explosion-proof valve 11--Circulating water control valve

12--The feed gas pipeline inlet of the heater (or the feed gas inlet of the heater)

13--The outlet of the raw gas pipeline of the heater (or the outlet of the raw gas of the heater)

14--reactor gas raw material gas inlet 15--reactor tail gas outlet

16--Circulating water inlet 17--Circulating water outlet 18--Inlet of flue gas pipe

19--Exit of flue gas pipe 20--Gas distribution plate 21--Product outlet

22, 25--product collector 23--heat exchanger (condenser) 24--three-phase separator

26--Water phase collector 27--Product tank 28--Tail gas vent valve

Detailed ways

The utility model will be described in detail below in conjunction with the accompanying drawings, but the implementation scope of the utility model is not limited.

The Fischer-Tropsch synthesis reaction provided by the utility model is a fixed-bed device for making high-quality liquid hydrocarbons. The reactors provided in the device can be two sets of reactors, or multiple sets of reactors connected in series, wherein each reaction The device can be a single-tube fixed bed or a multi-tube fixed bed.

Embodiment one:

As shown in Fig. 1 and Fig. 2, the present embodiment is the fixed-bed device that the Fischer-Tropsch synthesis reaction that two groups of single tube fixed-bed reactors (Fig. 1) are formed, concrete structure is as follows:

The device includes a reactor 4, a heater 1 arranged at the bottom of the reactor 4, whose function is to make the feed gas and circulating water reach a suitable preheating temperature, and then pass through the catalyst bed 3 and the outside of the reactor 4 from bottom to top. The sleeve pipe 5;, the heater 1 is provided with a heating medium (flue gas) pipeline, the inlet 18 of the flue gas pipeline is opened at the top of the heater, and the outlet 19 of the flue gas pipeline is opened at the heater The lower part of the heater is used to heat the circulating water entering the heater through the flue gas pipe, and the circulating water inlet 16 and the circulating water outlet 17 are respectively opened on the wall of the heater, and the circulating water outlet 17 is opened on the top of the heater, and It communicates with the sleeve pipe 5 outside the reactor 4; a feed gas pipeline is arranged in the heater 4, and the inlet 12 of the feed gas pipeline of the heater 4 and the outlet 13 of the feed gas pipeline of the heater 4 are arranged at the heating On the wall of the device 4, the outlet 13 of the feed gas pipeline of the heater 4 communicates with the feed gas inlet 14 of the reactor, and the feed gas in the feed gas pipeline is heated to a suitable preheating temperature by hot circulating water. temperature, and then enter the reactor for reaction through the outlet 13 of the feed gas pipeline of the heater and the feed gas inlet 14 of the reactor.

The product outlet 21 place at the bottom of the reactor 4 is also connected successively with a product collector 22 and a product tank 27, and the product collector 22 is used to collect the product that the boiling point generated by the reaction in the reactor is higher than the product of the reaction temperature. The product trough 27 is used to collect the product conveyed from the product collector. The top of the reactor 4 is connected in series with a heat exchanger 23 with a condensation function and a three-phase separator 24 with a separation function, so that the product generated by the reaction flows through the heat exchanger 23 and the three-phase separator 24, and is condensed first. , to screen out liquid hydrocarbon products and unconverted synthesis gas, and then carry out water phase, oil phase and gas phase separation to above-mentioned lower boiling point hydrocarbons and water and unconverted synthesis gas in this three-phase separator 24, The oil phase can be sent to the product tank 27 as a low-temperature condensed product after decompression, and the gas phase enters the next group of reactors to continue the reaction, so that the reaction of the raw material gas is more complete.

The above-mentioned fixed bed device is also provided with a flue gas inlet 18 and a flue gas outlet 19 on the wall of the heater 1, the flue gas inlet 18 is at the top of the heater, and the flue gas outlet 19 is at the bottom for heating The circulating water inside the device 1 is heated to a predetermined temperature.

The upper part of the sleeve pipe 5 outside the reactor 4 is also connected with a water storage tank 7, which is used to store the circulating water flowing out from the sleeve pipe 5, and the water storage tank 7 can timely adjust the temperature of the circulating water, Pressure and liquid level are regulated. The water storage tank 7 is also provided with a liquid level gauge 8, an inlet and outlet valve 9 (and more preferably an explosion-proof valve (or safety valve) 10) to monitor the water level and timely eliminate the The safety hazard of excessive water pressure rise.

The lower end of the water storage tank 7 is provided with a circulating pipeline connected with the circulating water inlet 16 provided on the heater 1. When the circulating water rises to the water storage tank 7, the temperature drops after it exchanges heat with the outside, and then due to Gravity or the action of the circulation pump 2, and under the control of the circulation water control valve 11, flow down from the external circulation line to re-enter the bottom of the casing to start circulation.

The temperature of the catalyst bed 3 in the entire reactor 4 is always maintained in the "constant temperature range", which ensures the smooth progress of the reaction, improves the conversion rate of the synthesis gas, and makes the single-pass conversion rate of the first group of reactors of the synthesis gas reach more than 65%. The single-pass conversion rate of the second group of reactors can reach 85%. The water in the circulation pipe flows very fast due to the action of gravity, which can quickly take away the heat of reaction and effectively supplement the low-temperature zone. The difference in water temperature does not exceed 4°C, which ensures the smooth progress of heat exchange in the outer wall 6 of the casing. , improving the efficiency of the whole reactor. The water storage tank 7, the liquid level gauge 8 and the safety valve 10 installed in the utility model are used to monitor the situation of the water level and eliminate in time the potential safety hazard that the water pressure rises too fast due to excessive heat absorption.

The gas coming out from the top of the reactor 4 comprises unreacted feed gas and the light hydrocarbon products of generation, and its temperature is still very high. After being condensed through the heat exchanger (condensation) 23, the temperature is close to room temperature and enters the heat exchanger. In the three-phase separator 24 connected with 23, a very small amount of low carbon hydrocarbons (CH ₄ etc.) The heater 23 and the three-phase separator 24 are then vented through the tail gas vent valve 28 or used as heating fuel. The liquid phase substances discharged from the three-phase separator 24 include liquid hydrocarbons and generated water, wherein the liquid hydrocarbons enter the product collector 25, and after decompression, they are sent to the product tank 27 for further processing, and the water phase enters the water phase collector. 26 (also known as the reaction water intermediate tank), and then go to the rectification recovery unit to recover the oxygen-containing organic matter in the water. The heavy hydrocarbons with a boiling point higher than the reaction temperature generated in the reaction enter the product collector 22 (also known as the low-temperature condensate intermediate tank) due to the effect of self gravity, and are sent to the product tank 27 for further processing after decompression.

Embodiment two:

As shown in Fig. 2 and Fig. 3, it is the fixed bed device that the Fischer-Tropsch synthesis reaction that two groups of multi-tubular reactors are formed, and the difference of Fig. 1 is that each group of reactors 4 is a multi-tube (gas pipeline) fixed bed, This multipipe (gas pipeline) is vertically arranged above the gas distribution plate 20 that the lower end of the reactor 4 is provided with, and adopts circulation line II to utilize circulation pump to carry out forced circulation to circulating water, makes circulating water flow fast like this, and circulating water temperature difference Smaller, more conducive to the Fischer-Tropsch synthesis reaction, and the production capacity of the multi-tube fixed bed is greater. Before the gas comes out from the reactor tail gas outlet 15 and enters the second group of reactors 4, it will go through the condenser 23 and the three-phase product separator 24 and then enter the second group of reactors to continue the reaction. The purpose is to separate and enter the second group of reactions. The hydrocarbons in the gas in reactor 4 can reduce the impact of hydrocarbon products on the Fischer-Tropsch synthesis reaction, and increase the partial pressure of unconverted synthesis gas and light hydrocarbon gas, which is conducive to improving the conversion rate and selectivity of the second group of reactors 4. The entire device process is basically the same as that of Example 1, and the device has been in good condition for more than one year. The single-pass conversion rate of CO reaches 80%, and the selectivity of C ₅ ⁺ reaches more than 80%. Although this scheme increases the cost of the reactor, it reduces the investment in the tail gas separation device and the power plant, expands the production capacity, increases the benefit, and can continue to increase the number of reactors according to the reaction needs.

The advantage of utilizing the fixed bed device of the present utility model to carry out the Fischer-Tropsch reaction is:

(1) The raw material gas can exchange heat in the circulating water heater, which achieves the rational utilization of energy.

(2) Use the heat exchange medium water to take heat and replenish heat from the reactor, which fully utilizes the characteristics of large heat capacity of water, and can choose self-heating cycle I and high-pressure pump forced cycle II according to different reaction conditions There are two different methods, and the flow rate of the pump can be adjusted at any time, which can remove a large amount of reaction heat and keep the reaction temperature basically constant. Therefore, the utility model is applicable to a wide range of reaction systems.

(3) The water storage tank can monitor the liquid level at any time, and adjust the water volume according to the needs, and the safety valve has a certain pressure range, which can be automatically overpressured and emptied, ensuring the safe operation of the device.

(4) The product is directly separated according to the difference in boiling point to prepare for subsequent product refining, and the water phase is rectified and recovered, which is energy-saving and environmentally friendly.

(5) The tail gas is not circulated, but directly vented or burned as fuel, which reduces the power plant, saves investment, and is simple and easy to operate. It is suitable for small and medium-sized Fischer-Tropsch synthesis devices.

(6) The program has been practically applied and operated for more than a year, and there has never been a shutdown failure due to process or equipment reasons.

(7) The single-pass conversion rate of CO reaches 80%, and the selectivity of C ₅ ⁺ is not lower than 80%.

(8) This scheme can also continue to add a third group or more groups of reactors, wherein each group of reactors reacts in series, and after the products of each group are condensed and separated to remove liquid hydrocarbons, the tail gas enters the next group of reactors to continue the reaction. Until the synthesis gas conversion reaches a higher level.

Claims (10)

1. fixed bed device that is used for Fischer-Tropsch synthesis, it is characterized in that: it is made up of this fixed bed device the fixed bed that two groups of head and the tail are contacted mutually at least, every group of fixed bed includes reactor, the corresponding well heater that is connected with this reactor, the sleeve pipe that joins with this well heater, interchanger and triphase separator, wherein, be provided with unstripped gas pipeline and heating medium pipeline in the well heater of every group of fixed bed, the wall of well heater is provided with unstripped gas inlet and unstripped gas outlet, this unstripped gas outlet is connected with this bank of reactor, also be provided with the heating medium inlet on the well heater wall, the heating medium outlet, and the recirculated water of well heater inlet and circulating water outlet, the circulating water outlet of every group of well heater communicates with this group sleeve pipe, all is connected with interchanger and triphase separator successively between the reactor of described two groups of polyphones.

2. the fixed bed device that is used for Fischer-Tropsch synthesis as claimed in claim 1, it is characterized in that: this recirculated water inlet is opened in the bottom of the wall of well heater, circulating water outlet is opened in the top of the wall of well heater, and this circulating water outlet communicates with described sleeve pipe.

3. the fixed bed device that is used for Fischer-Tropsch synthesis as claimed in claim 1 is characterized in that: the bottom of described each bank of reactor all is connected with product collector and product groove successively.

4. the fixed bed device that is used for Fischer-Tropsch synthesis as claimed in claim 3 is characterized in that: the top of described each bank of reactor all is connected with interchanger, triphase separator.

5. the fixed bed device that is used for Fischer-Tropsch synthesis as claimed in claim 1, it is characterized in that: the inner heating medium pipeline that is provided with of described well heater is a flue gas duct, described heating medium inlet is the inlet of flue gas duct, and the heating medium outlet is the outlet of flue gas duct.

6. the fixed bed device that is used for Fischer-Tropsch synthesis as claimed in claim 1 is characterized in that: described telescopic top is provided with circulating water outlet, and this sleeve pipe also is connected with the water tank that is used for storing effusive recirculated water from this sleeve pipe by circulating water outlet.

7. the fixed bed device that is used for Fischer-Tropsch synthesis as claimed in claim 6 is characterized in that: described water tank is provided with liquidometer and/or turnover valve.

8. the fixed bed device that is used for Fischer-Tropsch synthesis as claimed in claim 7 is characterized in that: also be provided with explosion trap on the described water tank.

9. the fixed bed device that is used for Fischer-Tropsch synthesis as claimed in claim 6, it is characterized in that: described water tank is provided with the circulation line that communicates with the recirculated water inlet offered on the well heater, and this circulation line be the natural circulation pipeline and the cycle of higher pressure pipeline of parallel connection.

10. as each described fixed bed device that is used for Fischer-Tropsch synthesis of claim 1-9, it is characterized in that: unstripped gas pipeline and heating medium pipeline are spiral pipe.

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