CN107254327B

CN107254327B - Fischer-Tropsch synthetic oil process

Info

Publication number: CN107254327B
Application number: CN201710411926.3A
Authority: CN
Inventors: 李管社; 吴伟伟; 曹红英; 王丽; 李芳玲; 范霄卿; 雷永杰; 郑强
Original assignee: Sinopec Engineering Group Co Ltd; Sinopec Ningbo Engineering Co Ltd; Sinopec Ningbo Technology Research Institute
Current assignee: Sinopec Engineering Group Co Ltd; Sinopec Ningbo Engineering Co Ltd; Sinopec Ningbo Technology Research Institute
Priority date: 2017-06-05
Filing date: 2017-06-05
Publication date: 2021-12-17
Anticipated expiration: 2037-06-05
Also published as: CN107254327A

Abstract

The invention relates to a Fischer-Tropsch synthetic oil process, which comprises a raw material synthetic gas preheater, a slurry bed F-T synthetic reactor and a circulating gas compressor, wherein an outlet of the raw material synthetic gas preheater is communicated with an inlet at the bottom of the slurry bed F-T synthetic reactor, a heat exchanger tube group is arranged in the slurry bed F-T synthetic reactor, an inlet of the heat exchanger tube group is communicated with an outlet of the circulating gas compressor, and an outlet of the heat exchanger tube group is communicated with an inlet of the raw material synthetic gas preheater. The top of the slurry bed F-T synthesis reactor is provided with the heat exchanger tube group, the outlet temperature of reaction tail gas is reduced by utilizing the heat absorption of the circulating tail gas, the heat utilization rate of a system is improved, the condensation of high-carbon hydrocarbons in the reaction tail gas is increased, the entrainment of the reaction tail gas to product liquid drops can be reduced, the yield of added-value product wax is improved, the condensation of the high-carbon hydrocarbons in the reaction tail gas is promoted, the capture capacity of a fine powder catalyst is improved, the fine powder catalyst is left in the slurry bed reactor, and the utilization rate of the fine powder catalyst is improved.

Description

Fischer-Tropsch synthetic oil process

Technical Field

The invention relates to a Fischer-Tropsch synthesis oil process.

Background

Coal and natural gas have been replacing petroleum in the beginning of this century, and have been the leading place in energy structures. In order to adapt to the inevitable trend of energy and chemical raw material route transformation and relieve the increasingly tense supply and demand contradiction of diesel and gasoline, the research and development of the production technology of replacing liquid fuel becomes the first mission of technicians in the petrochemical industry at home and abroad at present.

The Fischer-Tropsch (F-T) synthesis technology is the liquid hydrocarbon synthesis technology invented in F.Fischer and H.Tropsh in the thirty years, and is an important technology in the production technology of replacing liquid fuel. The core reaction of the technology is the F-T synthesis reaction, and three types of reactors are used industrially at present: fixed bed reactors, fluidized bed reactors and slurry bed reactors. Among the three reactors, the slurry bed reactor is widely used due to its characteristics of good heat transfer and mass transfer effects, low pressure drop, low investment cost, and on-line loading and unloading of the catalyst. The traditional slurry bed F-T synthetic oil process uses coal and natural gas as raw materials, and makes synthetic gas with a certain carbon-hydrogen ratio be bubbled and blown in the slurry bed reactor, and makes the F-T synthetic reaction pass through liquid-phase medium containing granular catalyst. The product wax is discharged from the middle part of the reactor, the liquid and solid are filtered and separated to obtain the product wax and the catalyst, and then the product wax and the catalyst are sent to a product wax storage tank, and the catalyst returns to the reactor to continuously participate in the reaction; the light oil product and the unreacted tail gas carry partial product wax and fine powder catalyst, and the light oil product and the F-T synthetic wastewater are separated by sending the light oil product and the unreacted tail gas to a cooling process after the light oil product and the unreacted tail gas are separated by a demister.

The temperature of the slurry bed F-T synthesis reaction is controlled to be about 220 ℃, the reaction pressure is about 2.7MPa, and the boiling point of the F-T synthesis product is higher than the temperature, the solid catalyst mixed in the liquid is separated in a liquid form through a liquid-solid separator and is sent to a product storage tank; the fischer-tropsch synthesis product, which has a boiling point below the outlet temperature (about 215 c), will be passed in gaseous form, together with unreacted tail gas, up through a demister to remove entrained droplets and catalyst, and sent to a cold separation section. The separation of the product wax and light oil in the reactor is not strictly in accordance with the above theoretical analysis due to various factors in actual production. The fact that the gas phase entering the demister upwards contains a significant amount of C17+ hydrocarbons, and the liquid phase remaining in the reactor also contains a certain amount of C16-has been verified by analyzing the composition of the product light oil and the product wax. When the composition of the product is analyzed, about 4.5 percent of C16-lightness exists in the high value-added product wax; approximately 18.0% of C17+ hydrocarbons are present in the light oil product. In addition, when equipment is shut down and overhauled, a large amount of solid wax is condensed from the outlet of the reactor to the inlet of the cooling equipment, and the wax contains a large amount of fine powder catalyst.

A combined gas-liquid separator for a catalyst production device, which is a chinese utility model patent with an authorization publication number of CN203663646U (application number of CN201420010487.7), wherein the disclosed combined gas-liquid separator comprises a cyclone plate demister and a wire mesh demister, the cyclone plate demister is composed of an outer cylinder, an inner cylinder, a blind plate and blades, a fixed ring and a support ring are adopted to be fixed on the inner wall of the tower, and the airflow rises from the bottom of the tower and is thrown and separated by the blades with large particle size; the wire mesh demister is a wire mesh block formed by mutually connecting a grid plate and a wire mesh, the wire mesh block is fixed on the inner wall of the tower through a gland and a support piece, and droplets with small particle sizes form large droplets on the wire mesh to fall and separate through adsorption force and gravity. The technology can separate the mist with large and small particle sizes in the gas, reduce the film forming rate and pressure drop of the gas, improve the operation condition, optimize the process index, reduce the corrosion of equipment, prolong the service life, increase the treatment capacity and recover valuable materials. The efficient demister can separate paraffin droplets larger than 8 microns and catalyst particles larger than 5 microns from gas at the outlet of the reactor simultaneously. This has two disadvantages for slurry bed fischer-tropsch synthesis reactors, firstly, the effect is poor for removing the paraffin droplets smaller than 8 μm and the catalyst particles smaller than 5 μm in the gas phase; secondly, the tail gas temperature at the outlet of the reactor is not reduced, so that a part of C17+ hydrocarbon passes through the demister in a gas phase state, enters a cooling process, is condensed after being cooled to block a pipeline or enters a light oil tank along with light oil, and the content of the C17+ hydrocarbon in the product light oil reaches 18.0 percent.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a Fischer-Tropsch synthesis oil process which can reduce the catalyst and wax oil brought out by reaction tail gas so as to improve the yield of product wax and the energy efficiency index of a system.

The technical scheme adopted by the invention for solving the problems is as follows: a Fischer-Tropsch synthetic oil process is realized through a Fischer-Tropsch synthetic oil process system, the Fischer-Tropsch synthetic oil process system comprises a raw material synthetic gas preheater, a slurry bed F-T synthetic reactor and a circulating gas compressor, an outlet of the raw material synthetic gas preheater is communicated with an inlet at the bottom of the slurry bed F-T synthetic reactor, and the Fischer-Tropsch synthetic oil process is characterized in that: and the top of the inner cavity of the slurry bed F-T synthesis reactor is provided with a heat exchanger tube group, the inlet of the heat exchanger tube group is communicated with the outlet of the circulating gas compressor, and the outlet of the heat exchanger tube group is communicated with the inlet of the raw material synthesis gas preheater.

In order to improve the heat energy utilization rate of the system, a baffle plate group is welded outside a heat exchange pipe of the heat exchanger pipe group.

Preferably, the set of baffles reduces the temperature of the reaction off-gas in the slurry bed fischer-tropsch synthesis reactor to between 165 ℃ and 185 ℃.

Preferably, the baffle groups preheat the recycle tail gas input by the recycle gas compressor to 110-130 ℃.

In order to increase the heat exchange capacity of the system under the condition of fixed heat exchange area, the heat exchanger tube group comprises a central tube and air inlet tubes distributed on two sides of the central tube, the lower ends of the air inlet tubes are respectively communicated with the central tube, the upper end of one air inlet tube extends out of the slurry bed F-T synthesis reactor to form an inlet of the heat exchanger tube group, and the upper end of the central tube extends out of the slurry bed F-T synthesis reactor to form an outlet of the heat exchanger tube group.

Compared with the prior art, the invention has the advantages that:

(1) the heat exchanger tube group of the external welding baffle plate is arranged at the top of the slurry bed F-T synthesis reactor, the outlet temperature of the reaction tail gas is reduced by utilizing the heat absorption of the circulating tail gas, the condensation of high carbon hydrocarbon in the reaction tail gas is increased, the entrainment of the reaction tail gas to product liquid drops is reduced, and the yield of the value-added product wax is improved;

(2) the invention arranges the heat exchanger tube group of the external welding baffle plate on the top of the slurry bed F-T synthesis reactor, reduces the outlet temperature of the reaction tail gas, promotes the condensation of high carbon hydrocarbon in the reaction tail gas, improves the capture capability of the baffle plate surface on the fine powder catalyst, retains the fine powder catalyst in the slurry bed reactor, and improves the utilization rate of the fine powder catalyst;

(3) the invention utilizes the heat exchanger tube group to preheat the temperature of the circulating tail gas, can reduce 33.3-46.7% of the heat required for preheating the circulating tail gas to 210 ℃, and improves the heat utilization rate of the system.

Drawings

FIG. 1 is a schematic diagram of a Fischer-Tropsch synthesis oil process system in an embodiment of the invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

The F-T synthetic oil product has complex components, mainly straight-chain alkane and alkene. The boiling point of linear alkanes is regularly increased with increasing molecular weight, as shown in table 1. As can be seen from Table 1, at normal temperature and one atmosphere pressure, C16-below is liquid and gas, and C17+ above is solid. The boiling point of undecane was 195.8 deg.C, that of dodecane was 216.3 deg.C, that of hexadecane was 280.0 deg.C and that of heptadecane was 303.0 deg.C at atmospheric pressure. The boiling point of a compound is the temperature at which the vapor pressure of the compound reaches equilibrium with the ambient pressure. The vapor pressure of the hydrocarbon in equilibrium with the ambient pressure rising to reach boiling point will also rise accordingly, which requires an increase in temperature to raise the vapor pressure, i.e., boiling point, of the hydrocarbon. The pressure in the F-T synthesis reactor system is about 2.7MPa, and the boiling point of the hydrocarbon compounds is greatly increased compared with that of the hydrocarbon compounds under normal pressure, so that the content of high-carbon hydrocarbons in tail gas is favorably reduced.

TABLE 1 melting and boiling points of some n-alkanes at atmospheric pressure

The boiling point of linear alkanes is determined by the size of the intermolecular attraction, and the greater the intermolecular attraction, the more energy must be provided to boil, so the higher the boiling point. The boiling points of the components listed in Table 1 are those of pure materials at one atmosphere pressure, while the boiling point of the liquid phase in the reactor, i.e., the F-T synthesis product, is a multi-component, three-phase (gas, liquid, solid) mixture, and the separation of the product light oil from the product wax is relatively difficult due to the many factors in the reactor, such as the F-T synthesis reaction conditions, the phase-to-phase adsorption conditions between the three phases, the attractive forces between the reaction products, and the surface tension, as evidenced by the fact that the light oil product contains about 18% wax (C17+) and the heavy oil product contains about 4.5% light oil (C16-).

F-T synthetic oil product analysis shows that when the tail gas outlet temperature is about 215 ℃, the C17+ component in the light oil accounts for about 18.0 percent of the total weight of the light oil product; when the outlet temperature of the tail gas is about 210 ℃, the C17+ component in the light oil accounts for about 16.5 percent of the total amount of the light oil. The outlet temperature of the tail gas is reduced by 5 ℃, and the content of C17+ components in the light oil is reduced by about 1.5%, which shows that the reduction of the outlet temperature of the reaction tail gas has obvious effect on reducing the content of C17+ components in the light oil. On the other hand, the test data show that when the outlet temperature of the tail gas is about 215 ℃, the C16-component in the heavy oil accounts for about 4.45 percent of the heavy oil; when the outlet temperature of the tail gas is about 210 ℃, the C16-component in the heavy oil accounts for 4.147% of the light oil. The outlet temperature of the tail gas is reduced by 5 ℃, the content of C16-components in the light oil is reduced by about 0.3 percent, which shows that the reduction of the outlet temperature of the reaction tail gas has little influence on the content of C16-hydrocarbon in the heavy oil. The reason for analyzing the above is that the temperature of the reaction tail gas outlet is reduced by the heat exchanger, and a part of high-carbon hydrocarbon is impacted on the baffle plate to be condensed due to the temperature reduction, so that liquid drops are formed and grow up, the temperature of the periphery of the high-carbon hydrocarbon gradually rises along with the falling of the high-carbon hydrocarbon in the reactor, and a part of lower-carbon-number hydrocarbon in the part of high-carbon hydrocarbon absorbs heat and is gasified again and is mixed with the synthesis tail gas to enter the heat exchanger tube group again. Thus, when the condensation-heat absorption gasification cycle is repeated, more and more C17+ components are left in the reactor, and less C17+ components are carried out by the tail gas; the C16-component remaining in the reactor becomes less and less, and the C16-component carried out by the off-gas becomes more and more.

The content of C17+ components in the light oil can be reduced by reducing the outlet temperature of the reaction tail gas, and the lower the outlet temperature of the reaction tail gas is, the less C17+ components are carried out. However, the outlet temperature cannot be lowered too much, which may destroy the temperature self-balance in the reactor and bring adverse effects to the F-T synthesis reaction, and the study considers that the outlet temperature of the reaction tail gas is lowered by 30-50 ℃ to reduce the content of C17+ components in the light oil to 10-6% of the total amount of the light oil, while comprehensively considering the influence of the carbon number distribution of the F-T synthesis product, the interaction among the substances, the van der Waals' attraction between molecules, and the temperature reduction on the composition of the light oil and the heavy oil.

The circulating tail gas with the pressure of 2.78MPa and the temperature of about 60 ℃ from the circulating compressor is mixed with the raw material synthesis gas with the pressure of 2.78MPa and the temperature of about 120 ℃ from the purification section, and the raw material synthesis gas needs to be preheated to about 210 ℃ by a synthesis gas preheater before entering the reactor for reaction, so that a large amount of heat is consumed.

In any gas-liquid contacting device, the gas always entrains some liquid, and the entrainment mechanism is mechanical action and condensation effect. The mechanical action produces droplets with diameters of almost 10 μm or more. Boiling the liquid or breaking up the bubbles as the liquid surface bubbles will produce droplets as large as 1000 microns and as small as a few microns; the liquid formed by the condensation of saturated vapor often produces very fine entrainment of droplets. The liquid drops carried by the reaction tail gas of the F-T synthesis reactor are mainly liquid drops generated by breaking bubbles when the boiling liquid and the liquid surface bubble. When reaction tail gas enters the heat exchange cooling pipe group, saturated gas is condensed to generate a large amount of fine mist droplets due to temperature reduction.

The mechanism of the baffle plate for mist capture can be divided into three types, namely inertial impaction, direct interception and brownian capture. The momentum of a droplet is proportional to the third power of the density and diameter of the liquid, so heavier and larger droplets are more likely to break off the gas stream and collide with objects placed in their straight line orientation, known as inertial impaction. The smaller diameter droplets can follow the gas flow and when the distance between the solids (the catchment nets) is smaller than the droplet diameter, these droplets are intercepted, which is called direct interception. When the diameter of the liquid drop is 1-10 micrometers, the liquid drop is mainly removed by direct interception. For droplets less than 1 micron in diameter, brownian capture becomes the primary capture mechanism, relying on brownian motion. The smaller the droplet diameter, the higher the efficiency of brownian capture. The transitions of these three mechanisms are not well defined.

In the F-T synthesis reactor, because raw material synthesis gas is blown in from the bottom of the slurry bed reactor, generated bubbles are broken on the liquid surface, liquid drops with the size of 1000 microns to several microns are generated, and catalyst fine powder is entrained into the gas phase to move upwards together. When the mixture containing the tail gas, the liquid drops and the fine catalyst particles moves to the top of the reactor to a position close to the heat exchanger tube group, the temperature of the mixture flow is gradually reduced, and a part of high-carbon hydrocarbon is gradually condensed by gas and converted into fog drops with extremely fine particles. And the mixture flows continuously upwards to impact the surface of the baffle plate, and the temperature of the mixture flow is further reduced due to the enhanced heat exchange effect of the metal baffle plate, wherein more high-carbon hydrocarbons are condensed due to the temperature reduction, and the captured catalyst fine powder is attached to the baffle plate to promote the capture of more liquid drops and catalyst fine powder and grow gradually. When the liquid drops grow to a certain scale, the liquid drops and the catalyst wrapped in the flank drop through the diversion trench and return to the reactor to participate in the F-T synthesis reaction again.

As shown in FIG. 1, the Fischer-Tropsch synthesis oil process system in the embodiment comprises a raw material synthesis gas preheater 1, a slurry bed F-T synthesis reactor 2 and a recycle gas compressor 3. The top of the inner cavity of the slurry bed F-T synthesis reactor 2 is provided with a heat exchanger tube group 4, and a baffle group 5 is welded outside the heat exchange tube of the heat exchanger tube group 4.

The heat exchanger tube group 4 comprises a central tube and air inlet tubes distributed on two sides of the central tube, and the lower ends of the air inlet tubes are respectively communicated with the central tube. Therefore, the heat exchange capacity of the system is increased under the condition that the heat exchange area is fixed.

The upper end of one of the air inlet pipes extends out of the slurry bed F-T synthesis reactor 2 to form an inlet of a heat exchanger pipe group 4, the inlet of the heat exchanger pipe group 4 is communicated with an outlet of the circulating gas compressor 3, the upper end of the central pipe extends out of the slurry bed F-T synthesis reactor 2 to form an outlet of the heat exchanger pipe group 4, and the inlet of the heat exchanger pipe group 4 is communicated with the inlet of the raw material synthesis gas preheater 1. And the outlet of the raw synthesis gas preheater 1 is communicated with the inlet at the bottom of the slurry bed F-T synthesis reactor 2.

The circulating tail gas which comes out of the circulating compressor and has the pressure of 2.78MPa and the temperature of about 60 ℃ is sent into a heat exchange pipe of a heat exchanger pipe group 5 of a baffle group 5 welded outside the pipe arranged at the top of the slurry bed F-T synthesis reactor, the circulating tail gas enters a central pipe from an air inlet pipe, and in the flowing process, the heat in the reaction tail gas released in the reaction process of a reaction tank at the bottom of the slurry bed F-T synthesis reactor is absorbed, so that the temperature of the circulating tail gas is preheated to 110-130 ℃. The preheated circulating tail gas is conveyed into the raw material synthesis gas preheater 1 from the central pipe of the heat exchanger pipe group 5, then is mixed with the fresh synthesis gas 1 which comes from the purification section and enters the raw material synthesis gas preheater 1, and then is preheated to 210 ℃ through the raw material synthesis gas preheater 1, and then is sent into a reaction tank at the bottom of the slurry bed F-T synthesis reactor for F-T synthesis reaction. Unreacted synthesis gas, at about 220 ℃ and 2.76MPa, entrains product droplets formed by foam breaking and catalyst fine powder 3, leaves the reaction liquid level and enters the outside of the heat exchanger tube group 4 with the baffle plate group 5 upwards. The heat exchanger tube group 4 absorbs the heat in the unreacted synthesis gas to reduce the temperature of the unreacted synthesis gas by 30-50 ℃, and most of the high-carbon hydrocarbon is gradually condensed by the gas and converted into fog drops with extremely fine particles. The mixture flow continues to move upwards, the mixture flow impacts the surface of the baffle plate, the temperature of the mixture flow can be further reduced due to the fact that the metal baffle plate has the effect of enhancing heat exchange, more high-carbon hydrocarbons are condensed due to temperature reduction, and the high-carbon hydrocarbons and the catalyst fine powder captured by the high-carbon hydrocarbons are attached to the baffle plate, so that more liquid drops impacting the surface of the baffle plate and the catalyst fine powder are captured, and the liquid drops grow rapidly. When the liquid drops grow to a certain scale, the catalyst fine powder which is captured by the liquid drops falls back to a reaction tank at the bottom of the slurry bed F-T synthesis reactor through a diversion trench and participates in the F-T synthesis reaction again. The reaction tail gas from which the product liquid drops and the catalyst fine powder are removed is sent to a cooling separation section through a reaction tail gas outlet at the top of the slurry bed F-T synthesis reactor at the temperature of about 165-185 ℃, and the product light oil and the industrial wastewater are separated.

In the foregoing process: (1) the heat exchanger tube group 5 of the welding baffle plate is arranged at the top of the slurry bed F-T reactor, so that the pressurized circulating tail gas passes through the heat exchange tube and exchanges heat with the unreacted reaction tail gas outside the tube, the outlet temperature of the reaction tail gas is reduced, the temperature of the circulating tail gas is increased, the heat consumption of the preheater is reduced, and the energy efficiency index of the system is increased; (2) the pipeline of the heat exchanger tube group 5 is provided with two descending air inlet tubes and an ascending central tube, so that the energy conversion force of the system can be increased under the condition of fixed heat exchange area; (3) the baffle plate group 5 is welded outside the heat exchanger tube group 5, so that the heat exchange area of the heat exchanger tube group 5 can be increased by utilizing the excellent heat conduction performance of metal, the collision and foam interception and removal effects of reaction tail gas are increased, the condensation of high-carbon hydrocarbon in the reaction tail gas is promoted, and the capture rate of product liquid drops and catalyst fine powder in the reaction tail gas is improved; (4) the temperature of the reaction tail gas outlet is reduced to 165-185 ℃ by utilizing the heat exchanger tube group 5 with baffles welded outside the heat exchange tube, so that the product wax drops and catalyst fine powder carried in the tail gas can be greatly reduced, and the content of the C17+ component in the light oil is reduced to 10-6.0%; and (5) preheating the circulating tail gas to 110-130 ℃ by utilizing the heat exchanger tube group 5 with the baffle plates welded outside the tube, so that the total heat output required by the part for preheating the circulating tail gas in the raw material synthesis gas preheater 1 can be reduced to 53.3-66.7%.

Claims

1. A Fischer-Tropsch synthetic oil process is realized through a Fischer-Tropsch synthetic oil process system, the Fischer-Tropsch synthetic oil process system comprises a raw material synthetic gas preheater, a slurry bed F-T synthetic reactor and a circulating gas compressor, an outlet of the raw material synthetic gas preheater is communicated with an inlet at the bottom of the slurry bed F-T synthetic reactor, and the Fischer-Tropsch synthetic oil process is characterized in that: a heat exchanger tube group is arranged at the top of the inner cavity of the slurry bed F-T synthesis reactor, the inlet of the heat exchanger tube group is communicated with the outlet of the circulating gas compressor for conveying the circulating tail gas, and the outlet of the heat exchanger tube group is communicated with the inlet of the raw material synthesis gas preheater; a baffle plate group is welded outside the heat exchange pipe of the heat exchanger pipe group;

conveying the circulating tail gas from the circulating compressor into a heat exchange pipe arranged at the top of the slurry bed F-T synthesis reactor, absorbing the heat released in the reaction process of a reaction tank at the bottom of the slurry bed F-T synthesis reactor in the flowing process of the circulating tail gas, preheating the temperature of the circulating tail gas, conveying the preheated circulating tail gas into a raw material synthesis gas preheater, and conveying the preheated circulating tail gas into a reaction tank at the bottom of the slurry bed F-T synthesis reactor to perform F-T synthesis reaction;

the heat exchanger tube group reduces the temperature of reaction tail gas, and a part of high-carbon hydrocarbon is collided on a baffle plate and meets condensation, so that the temperature of the reaction tail gas outlet of the slurry bed F-T synthesis reactor is reduced to 165-185 ℃ by the heat exchanger tube group; the high carbon hydrocarbon and the captured catalyst fine powder are attached to the baffle plate to form liquid drops, and the liquid drops fall after growing up and return to a reaction tank at the bottom of the slurry bed F-T synthesis reactor to participate in the F-T synthesis reaction again; along with the falling of the liquid drops, the temperature of the periphery rises gradually, and a part of lower carbon number hydrocarbons in the high carbon number hydrocarbons absorb heat and are gasified again and are mixed with the synthetic tail gas to ascend again;

the heat exchanger tube group preheats the circulating tail gas input by the circulating gas compressor to 110-130 ℃.

2. The fischer-tropsch synthesis oil process of claim 1, wherein: the heat exchanger tube group comprises a central tube and air inlet tubes distributed on two sides of the central tube, the lower ends of the air inlet tubes are respectively communicated with the central tube, the upper end of one air inlet tube extends out of the slurry bed F-T synthesis reactor to form an inlet of the heat exchanger tube group, and the upper end of the central tube extends out of the slurry bed F-T synthesis reactor to form an outlet of the heat exchanger tube group.