A method for improving the start-up efficiency of a slurry bed fischer-tropsch synthesis system

Abstract

The present application relates to the technical field of Fischer-Tropsch synthesis, and particularly relates to a method for improving the starting efficiency of a slurry bed Fischer-Tropsch synthesis process, comprising the following steps: before the slurry bed Fischer-Tropsch synthesis system is stopped, the reduced catalyst in a catalyst reduction reactor is transferred to a catalyst storage tank for solidification storage; when the slurry bed Fischer-Tropsch synthesis system is started, a heat source is used to melt the catalyst in the catalyst storage tank, and the melted catalyst is directly put into use; the solidification storage step is: the catalyst in the catalyst storage tank is cooled and solidified, and the catalyst storage tank is process-isolated by nitrogen sealing and blind plate sealing. The present application can completely solve the waste problem of purifying and refining gas venting at the initial stage of device starting, effectively shorten the starting time after feeding and the starting time after maintenance, improve the device operation efficiency, and greatly save the starting cost, and improve the economic operation level of the coal-to-oil system.

Description

Technical Field

[0001] This invention relates to the field of Fischer-Tropsch synthesis technology, and more particularly to a method for improving the start-up efficiency of a slurry-bed Fischer-Tropsch synthesis process. Background Technology

[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] The indirect coal liquefaction process mainly includes coal gasification, coal gas purification, Fischer-Tropsch synthesis, and product separation and purification. Among these, the Fischer-Tropsch synthesis can only be achieved with the aid of a catalyst. In the slurry-bed Fischer-Tropsch synthesis process, regardless of whether a cobalt-based or iron-based catalyst is used, it needs to be further reduced to possess the physical structure and chemical state required for catalytic activity. Generally, the catalyst is reduced to an active catalyst in a reduction reactor before being fed into the slurry-bed reactor, or the catalyst is directly reduced using a Fischer-Tropsch synthesis reactor. The reduction of fresh catalyst is the starting point of industrial production and a crucial step in catalyst production and use. Improving the start-up efficiency of each unit and achieving full load while saving start-up costs are issues that need to be addressed in the research and development of indirect coal liquefaction.

[0004] In coal indirect liquefaction projects, conventional Fischer-Tropsch synthesis reactor start-up schemes typically involve adding a certain amount of start-up oil to the Fischer-Tropsch synthesis reactor and waiting for the catalyst reduction unit to add the reduced iron-based catalyst to the synthesis reaction system under certain temperature and pressure conditions. Since multiple Fischer-Tropsch synthesis reactors are paired with only one reduction reactor, and according to the design scale and reduction procedure of the reduction reactor, in addition to catalyst transfer and addition, it also needs to go through a reduction stage and an adjustment stage. Reducing a batch of fresh catalyst requires at least 72 hours, and during this process, a large amount of refined gas (i.e., synthesis gas, which is the main raw material gas for the Fischer-Tropsch synthesis reaction, and its main components are CO + H2) is vented from the system, resulting in absolute waste and is not conducive to the economic operation of coal indirect liquefaction projects.

[0005] Patent CN106350095A (publication date: January 25, 2017) provides a method for shortening the start-up time of a Fischer-Tropsch synthesis reaction system. This method involves a complete conversion of the gasified crude syngas to achieve a hydrogen content of over 80%. After removing acidic gases with low-temperature methanol washing, the syngas is sent to the synthesis unit for system replacement. Replacement is completed quickly, saving replacement time, reducing the venting of large amounts of syngas, and shortening the start-up time. Previously, the process required starting the PSA and hydrogenation compressors before start-up; the complete conversion process sends the syngas directly to the synthesis unit, reducing start-up time from over 3 hours to half an hour. This method, using a linked replacement process from the purification section to the synthesis section, only shortens the start-up time by about 2.5 hours, but it does not solve the problem of wasted refined gas during catalyst reduction during system start-up.

[0006] Patent CN110003933A (publication date: July 12, 2019) discloses a Fischer-Tropsch synthesis apparatus and method to improve the start-up efficiency of industrial Fischer-Tropsch synthesis. During initial start-up and after maintenance, the catalyst is reduced within the Fischer-Tropsch synthesis reactor. The large amount of catalyst reduced at one time significantly shortens the time it takes for the reactor to reach full load, thus improving start-up efficiency. However, this method still requires catalyst reduction only after initial start-up and after maintenance, which not only consumes time in the reduction process but also results in a large amount of refined gas being vented, causing waste. Furthermore, the catalyst reduced in situ within the synthesis reactor is not suitable for long-term storage.

[0007] Therefore, it is evident that a method to significantly shorten the start-up time after the completion of defect elimination in a slurry-bed Fischer-Tropsch synthesis system and completely solve the waste caused by the venting of refined gas is an urgent problem to be solved. Summary of the Invention

[0008] In view of this, the present invention provides a method for improving the start-up efficiency of a slurry bed Fischer-Tropsch synthesis system, solving the problems of excessive start-up time and waste caused by venting of purified gas during catalyst reduction.

[0009] This invention provides a method for improving the start-up efficiency of a slurry-bed Fischer-Tropsch synthesis system, wherein the slurry-bed Fischer-Tropsch synthesis system includes a catalyst reduction reactor, a catalyst storage tank, and a Fischer-Tropsch synthesis reactor;

[0010] The method includes the following steps: before the slurry bed Fischer-Tropsch synthesis system is shut down, the catalyst reduced in the catalyst reduction reactor is transferred to the catalyst storage tank for solidification and storage. When the slurry bed Fischer-Tropsch synthesis system is started up, a heat source is used to melt the catalyst in the catalyst storage tank so that the melted catalyst can be put into use directly.

[0011] The solidification and storage step is as follows: the catalyst in the catalyst storage tank is cooled and solidified, and the catalyst storage tank is isolated by nitrogen sealing and blind plates.

[0012] Preferably, the curing and storage time is 1 to 50 days, and more preferably 8 to 45 days.

[0013] Preferably, the slurry bed Fischer-Tropsch synthesis system further includes a pressurized nitrogen tank and a bubbling hot nitrogen tank. The top of the catalyst storage tank is connected to the pressurized nitrogen tank through a pressurization pipeline, and the bottom is connected to the bubbling hot nitrogen tank through a bubbling pipeline. The catalyst storage tank body is equipped with a heating device.

[0014] Preferably, the top of the catalyst storage tank is connected to the catalyst reduction reactor via a feed pipe, and the bottom of the catalyst storage tank is connected to the Fischer-Tropsch synthesis reactor via a discharge pipe.

[0015] Preferably, the heat tracing device uses steam heat tracing or electric heat tracing, and the heat tracing temperature during operation of the heat tracing device is above 200°C.

[0016] Preferably, the nitrogen temperature in the bubbling pipeline is 60-180℃, and the nitrogen flow rate is not less than 180m³. 3 / h, preferably 200m 3 / h.

[0017] Preferably, the bottom of the catalyst storage tank is designed in a conical shape.

[0018] Preferably, the solidification and storage step is as follows:

[0019] After the reduced catalyst is transferred to the catalyst storage tank, the feed pipeline is purged with gas to ensure that no catalyst remains in the feed pipeline; then the heating device of the catalyst storage tank is stopped; nitrogen is introduced through the bubbling hot nitrogen tank to gradually cool and solidify the catalyst slurry in the catalyst storage tank; blind flanges are installed on the feed pipeline, discharge pipeline and bubbling pipeline; nitrogen is purged into the pressurized nitrogen tank to nitrogen seal the catalyst storage tank, and then blind flanges are installed on the pressurized pipeline to keep the catalyst storage tank in a process isolation state.

[0020] Preferably, the top of the catalyst storage tank is also provided with a venting pipe. After the feed pipe is purged by gas flow, the pressure of the catalyst storage tank is released to atmospheric pressure through the venting pipe. A blind plate is installed on the venting pipe before the nitrogen sealing step.

[0021] Preferably, the gradual cooling and curing step is as follows:

[0022] (1) Control the nitrogen temperature in the bubbling pipeline at 150-160℃ and reduce the catalyst temperature in the catalyst storage tank to 150-160℃.

[0023] (2) Control the nitrogen temperature in the bubbling pipeline to 110-120℃ and reduce the catalyst temperature in the catalyst storage tank to 110-120℃;

[0024] (3) Control the nitrogen temperature in the bubbling pipeline to 70-80℃, reduce the catalyst temperature in the catalyst storage tank to 70-80℃, and the catalyst slurry basically solidifies; during the cooling process, control the pressure in the catalyst storage tank to be slightly positive.

[0025] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0026] (1) The present invention places the reduced catalyst in a catalyst storage tank in advance for solidification and storage. When the slurry bed Fischer-Tropsch synthesis system is started, it is heated and put into use immediately. There is no need to go through the initial catalyst reduction stage. Therefore, it can completely solve the problem of waste of purified gas venting in the early stage of unit start-up, effectively shorten the start-up time of Fischer-Tropsch synthesis unit feeding and maintenance (about 72 hours), and improve the operating efficiency of the unit.

[0027] (2) The above method of the present invention can save about RMB3 million in start-up costs, produce about 3,000 tons of crude oil in advance, improve the economic operation level of coal-to-oil system, and has practical and feasible technical guidance significance for large-scale industrial coal indirect liquefaction oil production projects.

[0028] (3) The solidification storage device of the present invention can ensure that the original performance of the catalyst (including catalyst morphology, reactivity, selectivity, product structure distribution, etc.) remains unchanged for up to 45 days of storage, so that it can be heated and melted at start-up and immediately put into the Fischer-Tropsch synthesis process. Attached Figure Description

[0029] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0030] Figure 1 This is a schematic diagram of the slurry-bed Fischer-Tropsch synthesis system of Embodiment 1 of the present invention;

[0031] Figure 2 These are scanning electron microscope (SEM) images of the catalyst after solidification and storage in Example 1 of this application at 25x (A) and 50x (B), and a 50x SEM image of the catalyst before solidification and storage (C).

[0032] In the diagram, 1. Catalyst storage tank; 2. Catalyst reduction reactor; 3. First Fischer-Tropsch synthesis reactor; 4. Second Fischer-Tropsch synthesis reactor; 5. Pressurized nitrogen tank; 6. Bubbling hot nitrogen tank; 7. Pressurized pipeline; 8. Bubbling pipeline; 9. Feed pipeline; 10. Discharge pipeline; 11. First valve; 12. Second valve; 13. Third valve; 14. Fourth valve; 15. Fifth valve; 16. Sixth valve; 17. Seventh valve; 18. Eighth valve; 19. Ninth valve; 20. Vent pipeline; 21. Blind flange. Detailed Implementation

[0033] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0034] As described in the background section, existing methods for improving the start-up efficiency of slurry bed Fischer-Tropsch synthesis systems cannot completely solve the problem of purified gas venting, and the time from system start-up to Fischer-Tropsch synthesis is too long, resulting in wasted time and increased costs.

[0035] In view of this, the present invention provides a method for improving the start-up efficiency of a slurry bed Fischer-Tropsch synthesis system, wherein the slurry bed Fischer-Tropsch synthesis system includes a catalyst reduction reactor 2, a catalyst storage tank 1, and a Fischer-Tropsch synthesis reactor;

[0036] The method includes the following steps: before the slurry bed Fischer-Tropsch synthesis system is shut down, the catalyst reduced in the catalyst reduction reactor 2 is transferred to the catalyst storage tank 1 for solidification and storage. When the slurry bed Fischer-Tropsch synthesis system is started up, a heat source is used to melt the catalyst in the catalyst storage tank 1 so that the melted catalyst can be put into use directly.

[0037] The solidification and storage step is as follows: the catalyst in the catalyst storage tank 1 is cooled and solidified, and the catalyst storage tank 1 is isolated by nitrogen sealing and blind plates.

[0038] The solidification storage time described in this invention is 1 to 45 days, preferably 8 to 40 days. In conventional Fischer-Tropsch synthesis processes, the catalyst storage tank 1 can meet the requirements for storage for nearly a week without deterioration. However, to prevent catalyst sedimentation, bubbling nitrogen needs to be continuously introduced during storage, resulting in the consumption of common media. Moreover, prolonged storage may lead to deterioration of catalyst activity, significantly reducing the efficiency of the Fischer-Tropsch synthesis reaction. However, the solidification storage method of this invention can ensure that the catalyst maintains good activity and does not deteriorate during long-term maintenance or troubleshooting work, and can be put into use immediately upon start-up without affecting the efficiency of the Fischer-Tropsch synthesis reaction and product quality.

[0039] The slurry-bed Fischer-Tropsch synthesis system of the present invention further includes a pressurized nitrogen tank 5 and a bubbling hot nitrogen tank 6. The top of the catalyst storage tank 1 is connected to the pressurized nitrogen tank 5 via a pressurization pipeline 7, and the bottom is connected to the bubbling hot nitrogen tank 6 via a bubbling pipeline 8. The pressurized nitrogen tank 5 ensures that the catalyst is in a nitrogen-sealed state before solidification and storage, preventing the catalyst from deteriorating due to contact with air. Furthermore, the pressure from the pressurized nitrogen tank 5 ensures that the catalyst in the catalyst storage tank 1 enters the Fischer-Tropsch synthesis reactor for catalytic reaction.

[0040] The catalyst storage tank 1 of this invention is equipped with a heating device. This invention does not impose special restrictions on the heating method of the heating device; steam heating or electric heating can be used. The heating temperature during operation of the heating device is above 200°C to ensure that the catalyst is in a slurry state and can be smoothly transported to the Fischer-Tropsch synthesis reactor, without reducing the efficiency of the Fischer-Tropsch synthesis reaction due to its lower temperature. The heating device is stopped before solidification and storage, but is immediately put into operation during start-up to provide a heat source to melt the solidified and stored catalyst into a flowable slurry.

[0041] The catalyst storage tank 1 of this invention is connected at the top to the catalyst reduction reactor 2 via a feed pipe 9, so that the reduced catalyst can smoothly enter the catalyst storage tank 1. The catalyst storage tank 1 is connected at the bottom to the Fischer-Tropsch synthesis reactor via a discharge pipe 10, so as to supply catalyst to the Fischer-Tropsch synthesis reactor.

[0042] The nitrogen temperature in the bubbling pipeline 8 of this invention is 60-180℃, and the nitrogen flow rate is not less than 180m³. 3 / h, preferably 200m 3 / h. By bubbling hot nitrogen gas into the bottom of the catalyst storage tank 1, a heat source is provided for the catalyst while effectively preventing catalyst sedimentation. Compared with the existing method of using a top agitator to prevent catalyst sedimentation, this method effectively avoids mechanical damage to the catalyst, saves power consumption, and the stored catalyst operates under conditions essentially the same as the catalyst reduction process during startup. The nitrogen gas temperature is lower than the heating temperature, which allows for control of the catalyst's cooling and solidification process.

[0043] The catalyst storage tank 1 of this invention has a conical bottom design. This effectively prevents catalyst accumulation. The inner wall of the cone is provided with an annular pipe, which facilitates the introduction of nitrogen gas or backflushing.

[0044] The solidification and storage steps of this invention are as follows: After the reduced catalyst is transferred to the catalyst storage tank 1, the feed pipeline 9 is purged with gas to ensure that no catalyst remains in the feed pipeline; then, the heating device of the catalyst storage tank 1 is stopped; nitrogen gas is introduced through the bubbling hot nitrogen tank 6 to gradually cool and solidify the catalyst slurry in the catalyst storage tank 1; blind flanges are installed on the feed pipeline 9, the discharge pipeline 10, and the bubbling pipeline 8; nitrogen gas is purged into the pressurized nitrogen tank 5 to nitrogen seal the catalyst storage tank 1, and then a blind flange is installed on the pressurized pipeline 7 to keep the catalyst storage tank 1 in a process isolation state. The above solidification and storage method can ensure that the catalyst does not deteriorate during long-term storage, thereby ensuring that the system can be put into use immediately after the catalyst is heated and melted when it is started up.

[0045] This invention also includes a vent pipe 20 at the top of the catalyst storage tank 1. After the feed pipe 9 is purged with gas, the pressure in the catalyst storage tank 1 is released to atmospheric pressure through the vent pipe 20 to prevent excessive pressure inside the container from causing the contents to spray out and cause damage. A blind flange is installed on the vent pipe 20 after the nitrogen sealing step. A blind flange is installed on the vent pipe 20 before the nitrogen sealing step to prevent the catalyst storage tank 1 from contacting air.

[0046] The gradual cooling and curing step of this invention is as follows:

[0047] (1) Control the nitrogen temperature in the bubbling pipeline 8 at 150-160℃ and reduce the catalyst temperature in the catalyst storage tank 1 to 150-160℃.

[0048] (2) Control the nitrogen temperature in the bubbling pipeline 8 to 110-120℃ and reduce the catalyst temperature in the catalyst storage tank 1 to 110-120℃.

[0049] (3) Control the nitrogen temperature in the bubbling pipeline 8 to 70-80℃, and reduce the catalyst temperature in the catalyst storage tank 1 to 70-80℃, so that the catalyst slurry is basically solidified; during the cooling process, the pressure in the catalyst storage tank 1 is controlled to be slightly positive.

[0050] By controlling the temperature and gradually cooling down for solidification, it is possible to effectively prevent the pressure from easily deforming or cracking due to excessively rapid cooling. At the same time, by lowering the temperature to 70-80℃, which is below the catalyst's active temperature, the catalyst will not react during the solidification and storage stage, thus ensuring the safety of the storage process.

[0051] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0052] Example 1

[0053] This embodiment provides a method for improving the start-up efficiency of a slurry-bed Fischer-Tropsch synthesis system, including the following steps:

[0054] Before the entire plant is shut down for troubleshooting, the system first uses the normal production process to reduce and adjust the fresh catalyst in the reduction reactor. After the catalyst adjustment is completed, the reduction reactor is not cooled down, and the catalyst is directly transferred to the catalyst storage tank 1. A schematic diagram of the slurry-bed Fischer-Tropsch synthesis system is shown below. Figure 1 As shown. The catalyst used in this embodiment is a low-temperature iron-based catalyst.

[0055] (I) Preparations before catalyst transfer

[0056] 1. Ensure that the discharge pipeline 10 from the catalyst storage tank 1 to the Fischer-Tropsch synthesis reactor is unobstructed. Flush the pipeline with liquid paraffin and pre-fill the catalyst storage tank 1 with a certain level of paraffin to fill the discharge pipeline 10 from the catalyst storage tank 1 to the Fischer-Tropsch synthesis reactor to ensure that the catalyst delivery process is unobstructed.

[0057] 2. Control the pressure in catalyst storage tank 1 to maintain a certain pressure difference between catalyst reduction reactor 2 and catalyst storage tank 1;

[0058] 3. Confirm that the heating of catalyst storage tank 1 is in normal working order, the return water temperature of the heating is not lower than 200℃, and the body temperature of catalyst storage tank 1 is not lower than 200℃;

[0059] 4. Open the third valve 13 and the fourth valve 14 of the bubbling pipeline 8, the seventh valve 17 and the eighth valve 18 of the pressurization pipeline 7, and the ninth valve 19 of the venting pipeline 20; the bubbling pipeline 8 where the third valve 13 is located is connected to the upper middle part of the conical bottom of the catalyst storage tank 1, and the bubbling pipeline 8 where the fourth valve 14 is located is connected to the tip of the conical bottom of the catalyst storage tank 1.

[0060] 5. Close the second valve 12 at the bottom of catalyst storage tank 1, close the fifth valve 15 from catalyst storage tank 1 to the first Fischer-Tropsch synthesis reactor 3, and close the sixth valve 16 from catalyst storage tank 1 to the second Fischer-Tropsch synthesis reactor 4.

[0061] (II) Catalyst storage tank 1 for solidification and storage

[0062] 1. Open the first valve 11 of the feed pipeline 9 to transport the reduced catalyst in the reduction reactor to the catalyst storage tank 1 through pressure difference, and open the ninth valve 19 to depressurize the catalyst storage tank 1.

[0063] 2. Introduce bubbling hot nitrogen into catalyst storage tank 1, open the third valve 13 and the fourth valve 14, and control the flow rate of hot nitrogen into catalyst storage tank 1.

[0064] 3. After the catalyst delivery is completed, the pressure of the catalyst storage tank 1 is adjusted and controlled to be positive and kept stable through the seventh valve 17 and the eighth valve 18 of the pressurization pipeline 7 and the ninth valve 19 of the venting pipeline 20.

[0065] 4. Stop the tracing steam for the catalyst storage tank 1, and open the third valve 13 and the fourth valve 14 of the bubbling pipe 8 to gradually cool and solidify the catalyst in the catalyst storage tank 1. The specific cooling steps are as follows:

[0066] Step 1: Control the temperature of the bubbling hot nitrogen gas at 160℃, and the flow rate of the bubbling nitrogen gas at the cone bottom should not be less than 200m³. 3 / h, reduce the catalyst temperature in catalyst storage tank 1 to 160℃;

[0067] Step 2: Control the temperature of the bubbling nitrogen to 120℃, and ensure the flow rate of the bubbling nitrogen at the bottom of the cone is not less than 200m³. 3 / h, reduce the catalyst temperature in catalyst storage tank 1 to 120℃;

[0068] Step 3: Control the temperature of the bubbling nitrogen to 80℃, and the flow rate of the bubbling nitrogen at the bottom of the cone should not be less than 200m³. 3 / h, the temperature of the catalyst in the catalyst storage tank 1 is reduced to 80℃, and the catalyst slurry is basically solidified; during the cooling process, the pressure in the catalyst storage tank 1 is controlled at a slightly positive pressure.

[0069] 5. After the catalyst in the catalyst storage tank 1 has cooled and solidified, close the third valve 13 and the fourth valve 14 of the bubbling pipeline 8 to stop the bubbling hot nitrogen from entering the catalyst storage tank 1.

[0070] (III) Catalyst storage tank 1 is isolated and nitrogen-sealed

[0071] 1. Close the second valve 12 at the bottom of the catalyst storage tank 1, and add a blind plate 21 after the second valve 12 to isolate the bottom discharge from the first Fischer-Tropsch synthesis reactor 3 and the second Fischer-Tropsch synthesis reactor 4.

[0072] 2. A blind flange is added after the first valve 11 of the top feed pipe 9 to isolate the feed from the reduction reactor.

[0073] 3. A blind flange is added after the third valve 13 and the fourth valve 14 of the bubbling pipeline 8 to isolate the bubbling hot nitrogen from the catalyst storage tank 1.

[0074] 4. A blind flange is added after the ninth valve 19 of the top vent pipe 20 to maintain positive pressure in the catalyst storage tank 1.

[0075] 5. A certain amount of nitrogen is introduced into the catalyst storage tank 1 through the seventh valve 17 and the eighth valve 18 of the pressurization pipeline 7, so that the pressure of the catalyst storage tank 1 is positive and remains stable. A blind plate is added after the seventh valve 17 and the eighth valve 18 to nitrogen seal the catalyst storage tank 1.

[0076] (iv) Application of solidified storage catalysts

[0077] 1. After the system overhaul is completed, immediately put the catalyst storage tank 1 with heated steam to melt the catalyst slurry, open the third valve 13 and the fourth valve 14 of the bubbling pipeline 8, and put the bubbling hot nitrogen into the tank normally, maintaining a certain flow rate to prevent the catalyst from settling.

[0078] 2. A certain pressure difference is controlled between the catalyst storage tank 1 and the first Fischer-Tropsch synthesis reactor 3 and the second Fischer-Tropsch synthesis reactor 4, and the temperatures of the first Fischer-Tropsch synthesis reactor 3 and the second Fischer-Tropsch synthesis reactor 4 are higher than 160°C.

[0079] 3. Sequentially open the second valve 12 at the bottom of the catalyst storage tank 1 and the fifth valve 15 on the pipeline to the first Fischer-Tropsch synthesis reactor 3 to add the reduced catalyst to the first Fischer-Tropsch synthesis reactor 3; or sequentially open the second valve 12 at the bottom of the catalyst storage tank 1 and the sixth valve 16 on the pipeline to the second Fischer-Tropsch synthesis reactor 4 to add the reduced catalyst to the second Fischer-Tropsch synthesis reactor 4; alternatively, sequentially open the second valve 12, the fifth valve 15, and the sixth valve 16 at the bottom of the catalyst storage tank 1 and simultaneously add catalyst to the first Fischer-Tropsch synthesis reactor 3 and the second Fischer-Tropsch synthesis reactor 4; proceed with the Fischer-Tropsch synthesis reaction according to the normal process.

[0080] The performance of the catalyst after 45 days of curing storage was compared with that of the catalyst before curing storage, as follows:

[0081] (1) Comparison of catalyst particle size distribution data

[0082] Table 1. Particle size distribution of the reduced slurry before and after catalyst solidification and storage (unit: %)

[0083]

[0084] Table 1 shows the comparison of particle size distribution of the reduction slurry before and after catalyst solidification and storage. As can be seen from Table 1, the particle size distribution of the reduction slurry before and after catalyst solidification and storage is basically the same, and the particle size has not changed significantly.

[0085] (2) Catalyst morphology

[0086] Figure 2 The images show the morphology of the solidified and stored catalyst under a scanning electron microscope at 25x (A) and 50x (B). The figures show that the catalyst particles are uniform in size and distribution, and their morphology remains a smooth sphere, consistent with that of the catalyst produced under normal conditions. Figure 2 C) No significant changes were observed compared to the previous version.

[0087] (3) Product distribution and selectivity

[0088] The following is a comparison of the proportions, carbon number distributions, conversion rates, and selectivity of the main products (Fischer-Tropsch paraffin, high-temperature condensate, and low-temperature condensate) of the Fischer-Tropsch synthesis system before and after solidification and storage:

[0089] Table 2. Proportion of major Fischer-Tropsch synthesis products before and after catalyst solidification and storage

[0090]

[0091] The proportions of the main Fischer-Tropsch synthesis products, Fischer-Tropsch paraffin, high-temperature condensate, and low-temperature condensate, remained basically consistent before and after catalyst solidification and storage, with no significant deviation in proportion. This indicates that catalyst solidification and storage do not affect the product proportion distribution.

[0092] Table 3 Comparison of carbon number distribution of major Fischer-Tropsch synthesis products before and after catalyst solidification and storage

[0093]

[0094] By comparing the carbon number distribution of the main products of Fischer-Tropsch synthesis before and after catalyst solidification and storage, the main carbon number distribution did not change significantly and remained basically the same, indicating that the solidification and storage of the catalyst did not affect the distribution of the main products of Fischer-Tropsch synthesis.

[0095] Table 4 Comparison of conversion rate and selectivity of Fischer-Tropsch synthesis system before and after catalyst solidification and storage.

[0096] substance <![CDATA[H2]]> CO <![CDATA[H2+CO]]> <![CDATA[CO+CO2]]> <![CDATA[CO2 selectivity]]> <![CDATA[CH4 selectivity]]> unit ％ ％ ％ ％ ％ ％ Conversion rate (before) 78.55 96.07 85.05 99.77 13.15 3.01 Conversion rate (after) 79.18 97.04 86.00 99.78 12.76 3.55

[0097] By comparing the conversion rates and selectivity of the Fischer-Tropsch synthesis system before and after catalyst solidification and storage, it can be seen that the conversion rates of H2, CO, H2+CO, and CO+CO2 in the Fischer-Tropsch synthesis system are all improved to varying degrees after catalyst solidification and storage, indicating that the catalyst performance is not affected after catalyst solidification and storage.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for improving the start-up efficiency of a slurry-bed Fischer-Tropsch synthesis system, the slurry-bed Fischer-Tropsch synthesis system comprising a catalyst reduction reactor, a catalyst storage tank, and a Fischer-Tropsch synthesis reactor, characterized in that, Includes the following steps: Before the slurry bed Fischer-Tropsch synthesis system is shut down, the catalyst reduced in the catalyst reduction reactor is transferred to the catalyst storage tank for solidification and storage. When the slurry bed Fischer-Tropsch synthesis system is started up, a heat source is used to melt the catalyst in the catalyst storage tank so that the melted catalyst can be put into use directly. The slurry-bed Fischer-Tropsch synthesis system also includes a pressurized nitrogen tank and a bubbling hot nitrogen tank. The top of the catalyst storage tank is connected to the pressurized nitrogen tank via a pressurization pipeline, and the bottom is connected to the bubbling hot nitrogen tank via a bubbling pipeline. The catalyst storage tank body is equipped with a heating device. The top of the catalyst storage tank is connected to the catalyst reduction reactor via a feed pipeline, and the bottom of the catalyst storage tank is connected to the Fischer-Tropsch synthesis reactor via a discharge pipeline. The solidification and storage steps are as follows: After the reduced catalyst is transferred to the catalyst storage tank, the feed pipeline is purged with gas to ensure that no catalyst remains in the feed pipeline; then the heating device of the catalyst storage tank is stopped; nitrogen is introduced through the bubbling hot nitrogen tank to gradually cool and solidify the catalyst slurry in the catalyst storage tank; blind flanges are installed on the feed pipeline, discharge pipeline and bubbling pipeline; nitrogen is purged into the pressurized nitrogen tank to nitrogen seal the catalyst storage tank, and then blind flanges are installed on the pressurized pipeline to keep the catalyst storage tank in a process isolation state.

2. The method as described in claim 1, characterized in that, The solidification and storage time is 1 to 50 days.

3. The method as described in claim 2, characterized in that, The solidification and storage time is 8 to 45 days.

4. The method as described in claim 1, characterized in that, The heat tracing device uses steam or electric heat tracing, and the heat tracing temperature during operation is above 200℃.

5. The method as described in claim 1, characterized in that, The nitrogen temperature in the bubbling pipeline is 60-180℃, and the nitrogen flow rate is not less than 180m³. 3 / h.

6. The method as described in claim 1, characterized in that, The nitrogen flow rate in the bubbling pipeline is 200 m³ / s. 3 / h.

7. The method as described in claim 1, characterized in that, The bottom of the catalyst storage tank is designed in a conical shape.

8. The method as described in claim 1, characterized in that, The catalyst storage tank is also equipped with a venting pipe at the top. After the feed pipe is purged by gas flow, the pressure of the catalyst storage tank is released to atmospheric pressure through the venting pipe. A blind flange is installed on the venting pipe before the nitrogen sealing step.

9. The method as described in claim 1, characterized in that, The gradual cooling and curing step is as follows: (1) Control the nitrogen temperature in the bubbling pipeline at 150~160℃ and reduce the catalyst temperature in the catalyst storage tank to 150~160℃; (2) Control the nitrogen temperature in the bubbling pipeline to 110~120℃ and reduce the catalyst temperature in the catalyst storage tank to 110~120℃; (3) Control the nitrogen temperature in the bubbling pipeline to 70~80℃, reduce the catalyst temperature in the catalyst storage tank to 70~80℃, and the catalyst slurry basically solidifies; during the cooling process, control the pressure in the catalyst storage tank to be slightly positive.

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