Method for reducing temperature of catalyst bed in reaction furnace of methane synthesis device
By adding demineralized water and nitrogen pipelines to the methane synthesis unit and optimizing the cooling process, the problems of slow catalyst bed cooling and dry burning of equipment were solved, achieving faster and safer cooling effect and reducing energy consumption and nitrogen consumption.
Patent Information
- Application Number
- CN202211500640.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-11-29
- Publication Date
- 2025-12-19
- Estimated Expiration
- 2042-11-29
AI Technical Summary
The slow cooling rate of the catalyst bed after shutdown of the methane synthesis unit leads to high energy consumption and a high risk of catalyst damage. In addition, the existing process suffers from problems such as dry burning of equipment and waste of nitrogen.
A demineralized water pipeline and a nitrogen connection pipeline were added at the inlet of the circulating compressor boiler water heat exchanger to change the process flow. The demineralized water and medium-pressure nitrogen were used to accelerate the cooling rate and optimize the cooling stage operation of the catalyst bed.
It accelerates the cooling rate of the catalyst bed, reduces energy consumption and the risk of equipment damage, improves cooling efficiency, protects the catalyst, and reduces nitrogen consumption.
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Figure CN115646370B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of temperature control in the process of methane synthesis, in particular to a method for reducing the temperature of catalyst bed in the reaction furnace of a methane synthesis device. BACKGROUND
[0002] After a certain period of methane synthesis, the carbon content of the broken catalyst in the reaction furnace can be as high as 48.2%, and the catalyst shows obvious carbon deposition. The carbon deposition reaction of CO can generate elemental carbon and adhere to the surface of the catalyst. Since the catalyst has a porous structure, the accumulation of elemental carbon to a certain extent can break the micropores in the catalyst, resulting in catalyst fragmentation. The continuously accumulated elemental carbon eventually becomes visible carbon powder, and the carbon powder caused by the fragmentation of the catalyst and the carbon deposition reaction together causes the pressure difference of the process gas between the inlet and outlet of the reaction furnace to rise. When the pressure difference rises above 150 kPa, the risk of catalyst fragmentation at the bottom of the reaction furnace due to excessive pressure is too high, and the catalyst bed must be treated, the catalyst is removed from the reaction furnace, and after screening to remove the broken catalyst and carbon powder, it is reloaded to reduce the pressure difference of the process gas between the inlet and outlet of the reaction furnace. Since the methane synthesis reaction is a chemical reaction that can release a large amount of heat, the temperature of the catalyst bed in the reaction furnace can reach more than 600℃ during operation. Since the removal, screening and reloading of the catalyst are all done manually, the temperature of the catalyst bed must be reduced to below 40℃ before the catalyst bed is treated.
[0003] The existing methanation synthesis process requires two-stage cooling. The slow cooling rate and long time in the first cooling stage result in long running time of the circulating compressor, increased energy consumption of the device, and affected maintenance schedule. Moreover, the temperature that the catalyst bed in the reaction furnace can reach in the first cooling stage is about 90℃, the cooling capacity is low, which affects the separation of water in the process gas in the circulating gas separation tank, and is not conducive to the protection of the catalyst.
[0004] After the methane synthesis device is shut down, the boiler water in the system stops flowing due to the stop of the steam generation by the steam drum. As the temperature of the process gas decreases, the temperature of the boiler water in the system also decreases, and the volume of the water decreases. Since the boiler water heat exchanger is at the highest point of the boiler water system, a local vacuum will eventually form at the top of the shell side of the boiler water heat exchanger. The tube side heat exchange tubes in the local vacuum range do not exchange heat with the shell side, resulting in dry burning, which can easily cause uneven expansion inside the equipment and crack the welds at the connection between the tube sheet and the heat exchange tubes, eventually leading to leakage of the heat exchanger.
[0005] The existing methanation synthesis process in the second cooling stage, four reaction furnaces can only be in series process, the cooling nitrogen gas used by the rear-end reaction furnace of the process flow comes from the outlet of the front-end reaction furnace, the temperature is higher, if the rear-end reaction furnace of the process flow needs to be overhauled, it will cause the cooling time to be too long and the waste of nitrogen gas. The medium-pressure nitrogen gas added at the raw material gas inlet must be heated by the first raw material gas heat exchanger and the second raw material gas heat exchanger before entering the reaction furnace for cooling, which reduces the cooling capacity of nitrogen gas and causes the loss of cold energy. SUMMARY
[0006] In view of the above-mentioned defects, the purpose of the present application is to accelerate the cooling rate of the first and second cooling stages after the methanation device is stopped, to make the catalyst bed dehydration faster and more thorough, to reduce the risk of condensation of steam water in the catalyst bed, and to protect the catalyst. A kind of methanation device reaction furnace catalyst bed cooling method.
[0007] The purpose of the present application is achieved by a kind of methanation device reaction furnace catalyst bed cooling method, including the first hand valve of desalted water on water is newly added in the inlet boiler water heat exchanger of circulating compressor on the pipeline side, the desalted water on water pipeline eight blind plate is newly added in the inlet boiler water heat exchanger of circulating compressor on the pipeline side, the second hand valve of desalted water on water is newly added in the inlet boiler water heat exchanger of circulating compressor on the pipeline side;Desalted water backwater first hand valve is newly added in the outlet pipeline of circulating compressor inlet boiler water heat exchanger, desalted water backwater pipeline eight blind plate is newly added in the outlet pipeline of circulating compressor inlet boiler water heat exchanger, desalted water backwater second hand valve is newly added in the outlet pipeline of circulating compressor inlet boiler water heat exchanger;Nitrogen gas pipeline is provided with connecting pipeline communicated with heating pipeline on the medium-pressure nitrogen gas pipeline, nitrogen gas communication pipeline hand valve and nitrogen gas communication pipeline check valve are arranged on the connecting pipeline.
[0008] The inlet pipeline of boiler water heat exchanger is provided with circulating compressor inlet boiler water heat exchanger on water pipeline hand valve, and the outlet pipeline of boiler water heat exchanger is provided with circulating compressor inlet boiler water heat exchanger backwater pipeline hand valve.
[0009] When the first cooling stage starts, the original boiler water pipeline is disabled and the newly added desalted water pipeline is put into use, then the shell side of the boiler water heat exchanger is exhausted at the top, so that the desalted water continuously flows in the boiler water heat exchanger;At the same time, the temperature of the shell side heat exchange water of the boiler water heat exchanger is reduced from 250 DEG C of boiler water to 50 DEG C of desalted water, so that the temperature of the process gas entering the circulating compressor inlet cooler is reduced, and the cooling rate of the first cooling stage is accelerated.
[0010] In the first cooling stage, the boiler water used by the boiler water heat exchanger is changed to the desalted water used by the fourth reaction furnace outlet desalted water heat exchanger, and the desalted water on water of the fourth reaction furnace outlet desalted water heat exchanger is connected to the boiler water on water pipeline of the boiler water heat exchanger.
[0011] At the beginning of the second cooling stage, the medium-pressure nitrogen hand valve is closed, and the nitrogen connecting pipeline hand valve is opened to introduce the medium-pressure nitrogen, which does not need to be heated by the first raw material gas heat exchanger and the second raw material gas heat exchanger to enter the reaction furnace.
[0012] In the second cooling stage, the methane synthesis device medium-pressure nitrogen inlet is changed to the desulfurization tank heating inlet valve front check valve front pipeline.
[0013] Due to the implementation of the above technical solution, the application has the following advantages:
[0014] 1. The cooling rate of the first cooling stage after the methane synthesis device is stopped is accelerated;
[0015] 2. The running time of the circulating compressor during the shutdown process of the methanation synthesis device is shortened, and the energy consumption of the device is reduced;
[0016] 3. The temperature reached in the first cooling stage after the methanation synthesis device is stopped is lower, and it is expected that the catalyst bed temperature of the reaction furnace can be reduced to 70℃, which is 20℃ lower than the original process;
[0017] 4. In the first cooling stage, the original boiler water pipeline is disabled and the newly added desalted water pipeline is put into use, and then the top exhaust of the boiler water heat exchanger shell is performed, so that the desalted water continuously flows in the boiler water heat exchanger, thereby avoiding the dry burning of the boiler water heat exchanger;
[0018] 5. The circulating compressor inlet temperature in the first cooling stage can be reduced to 40℃, which is 20℃ lower than the original process, so that the catalyst bed is dehydrated faster and more thoroughly, the risk of condensation of the catalyst bed vapor is reduced, and the catalyst is protected;
[0019] 6. The cooling process and operation method of the second cooling stage after the methanation synthesis device is stopped are changed, so that any one reaction furnace to be repaired can be placed at the front end of the cooling process, so that the cooling nitrogen enters the reaction furnace to be repaired first, accelerates the cooling rate of the reaction furnace to be repaired, and greatly improves the cooling efficiency;
[0020] 7. Due to the change of the process flow, in the second cooling stage, the nitrogen does not need to be heated by the first raw material gas heat exchanger and the second raw material gas heat exchanger to enter the reaction furnace, which accelerates the cooling rate and reduces the nitrogen consumption. BRIEF DESCRIPTION OF DRAWINGS
[0021] The specific structure of the application is given by the following drawings and examples:
[0022] Figure 1 It is a system structure schematic diagram of the application.
[0023] Legend: 1. Reactor No. 1, 2. Reactor No. 2, 3. Reactor No. 3, 4. Reactor No. 4, 5. Desulfurization tank, 6. No. 2 feed gas heat exchanger, 7. Supplementary methanation reaction heat exchanger, 8. No. 1 feed gas heat exchanger, 9. Demineralized water heat exchanger, 10. No. 4 reactor outlet demineralized water heat exchanger, 11. Boiler water heat exchanger, 12. Circulating gas separator, 13. Circulating compressor, 14. Steam heater, 15. Electric heater, 16. Medium-pressure nitrogen manual valve, 17. Desulfurization tank heating inlet valve, 18. Desulfurization tank heating inlet valve front check valve, 19. Main reactor heating inlet main valve, 20. No. 3 reactor heating inlet valve, 21. No. 4 reactor heating inlet valve, 22. No. 2 reactor feed gas shut-off valve, 23. No. 1 reactor inlet shut-off valve, 24. No. 1 reactor... 25. No. 1 Reactor Heating and Return Gas Shut-off Valve; 26. Heating and Return Gas Main Valve; 27. No. 2 Reactor Outlet Shut-off Valve; 28. No. 3 Reactor Heating and Return Gas Shut-off Valve; 29. No. 3 Reactor Outlet Shut-off Valve; 30. No. 4 Reactor Heating and Return Gas Shut-off Valve; 31. No. 4 Reactor Outlet Shut-off Valve; 32. Circulating Compressor Outlet Shut-off Valve; 33. Circulating Compressor Outlet Heating Valve; 34. Circulating Compressor Inlet Cooler; 35. First Hand Valve for Water Supply; 36. Water Supply Pipeline Blind Flange; 37. Second Hand Valve for Water Supply; 38. First Hand Valve for Water Return; 39. Water Return Pipeline Blind Flange; 40. Second Hand Valve for Water Return; 41. Hand Valve for Water Supply; 42. Hand Valve for Water Return; 43. Hand Valve for Nitrogen Connecting Pipeline; 44. Check Valve for Nitrogen Connecting Pipeline. Detailed Implementation
[0024] This application is not limited to the following embodiments, and the specific implementation method can be determined according to the technical solution of this application and the actual situation.
[0025] Example: Figure 1 As shown, a method for cooling the catalyst bed in the reactor of a methane synthesis unit includes adding a first manual valve 35 for demineralized water supply on the inlet pipeline side of the circulating compressor inlet boiler water heat exchanger 11, adding a figure-eight blind flange 36 for demineralized water supply pipeline on the inlet pipeline side of the circulating compressor inlet boiler water heat exchanger 11, and adding a second manual valve 37 for demineralized water supply on the inlet pipeline side of the circulating compressor inlet boiler water heat exchanger 11.
[0026] A first manual valve 38 for demineralized water return is added to the outlet pipeline side of the boiler water heat exchanger 11 at the inlet of the circulating compressor. A figure-eight blind flange 39 for demineralized water return is added to the outlet pipeline side of the boiler water heat exchanger 11 at the inlet of the circulating compressor. A second manual valve 40 for demineralized water return is added to the outlet pipeline side of the boiler water heat exchanger 11 at the inlet of the circulating compressor.
[0027] The connecting pipeline is communicated with the heating pipeline, and a nitrogen communication pipeline hand valve 43 and a nitrogen communication pipeline check valve 44 are arranged on the connecting pipeline.
[0028] Further, a circulating compressor inlet boiler water heat exchanger water inlet pipeline hand valve 41 is arranged on the boiler water inlet pipeline of the boiler water heat exchanger 11, and a circulating compressor inlet boiler water heat exchanger water return pipeline hand valve 42 is arranged on the boiler water outlet pipeline of the boiler water heat exchanger 11.
[0029] In use, in the first cooling stage, the boiler water used by the boiler water heat exchanger 11 is changed to the desalted water used by the desalted water heat exchanger 10 at the outlet of the fourth reaction furnace (the distance between the two heat exchangers on site is about 5 meters, the length of the newly added pipeline is short, and the cost is low), the desalted water of the desalted water heat exchanger 10 at the outlet of the fourth reaction furnace is connected to the boiler water inlet pipeline of the boiler water heat exchanger 11, the desalted water of the desalted water heat exchanger 10 at the outlet of the fourth reaction furnace is connected to the boiler water return pipeline of the boiler water heat exchanger 11, and the circulating compressor inlet boiler water heat exchanger is added with a desalted water inlet first hand valve 35, a circulating compressor inlet boiler water heat exchanger desalted water inlet pipeline 8-shaped blind plate 36, a circulating compressor inlet boiler water heat exchanger desalted water inlet second hand valve 37, a circulating compressor inlet boiler water heat exchanger desalted water return first hand valve 38, a circulating compressor inlet boiler water heat exchanger desalted water return pipeline 8-shaped blind plate 39, a circulating compressor inlet boiler water heat exchanger desalted water return second hand valve 40, a circulating compressor inlet boiler water heat exchanger water inlet pipeline hand valve 41, and a circulating compressor inlet boiler water heat exchanger water return pipeline hand valve 42.
[0030] At the beginning of the first cooling stage, the original boiler water pipeline is disabled and the newly added desalted water pipeline is put into use, and then the top of the boiler water heat exchanger 11 is exhausted to make the desalted water continuously flow in the boiler water heat exchanger 11, thereby avoiding dry burning of the boiler water heat exchanger 11; at the same time, the temperature of the shell side heat exchange water of the boiler water heat exchanger 11 is reduced from 250℃ of the boiler water to 50℃ of the desalted water, so that the temperature of the process gas entering the circulating compressor inlet cooler 34 is greatly reduced, the cooling rate of the first cooling stage is accelerated, the temperature of the circulating compressor 13 inlet in the first cooling stage is expected to be reduced to 40℃, the temperature of the catalyst bed of the final reaction furnace can be reduced to 70℃, which is 20℃ lower than that of the original process, the separation of water in the process gas in the circulating gas separation tank 12 is promoted, and the risk of gaseous water condensation in the catalyst bed is greatly reduced.
[0031] In the second cooling stage, the methane synthesis device medium pressure nitrogen inlet is changed to the desulfurization tank heating inlet valve before the check valve 18 at the front end of the pipeline, and a nitrogen connecting pipeline hand valve 43 and a nitrogen connecting pipeline check valve 44 are added. At the beginning of the second cooling stage, the medium pressure nitrogen hand valve 16 is closed, and the nitrogen connecting pipeline hand valve 43 is opened to introduce medium pressure nitrogen. Due to the change in the process flow, the nitrogen does not need to be heated by the first raw material gas heat exchanger 8 and the second raw material gas heat exchanger 6 before entering the reaction furnace, which accelerates the cooling rate.
[0032] By changing the cooling process of the four reaction furnaces using the pipelines in the original methane synthesis process, any reaction furnace that needs to be repaired can be placed at the front end of the cooling process, so that the cooling nitrogen enters the reaction furnace that needs to be repaired first, accelerates the cooling rate of the reaction furnace that needs to be repaired, and greatly improves the cooling efficiency.
[0033] If the first reaction furnace 1 needs to be repaired and the catalyst bed, and the other reaction furnaces do not need to be cooled to below 40°C, then in the second cooling stage, the cooling rate of the first reaction furnace 1 is mainly considered. At this time, the nitrogen connecting pipeline hand valve 43, the main reactor heating inlet total valve 19, the first reaction furnace inlet cut-off valve 23, the first reaction furnace outlet cut-off valve 24, the second reaction furnace outlet cut-off valve 27, the third reaction furnace outlet cut-off valve 29, and the fourth reaction furnace outlet cut-off valve 31 are opened, and the remaining valves are closed, so that the nitrogen enters the first reaction furnace 1 first, and then passes through the second reaction furnace 2, the third reaction furnace 3, and the fourth reaction furnace 4 in turn, and finally the nitrogen after absorbing heat is sent to the flare at the outlet of the fourth reaction furnace 4.
[0034] If the second reaction furnace 2 needs to be repaired and the catalyst bed, then the nitrogen connecting pipeline hand valve 43, the main reactor heating inlet total valve 19, the second reaction furnace raw material gas cut-off valve 22, the second reaction furnace outlet cut-off valve 27, the third reaction furnace outlet cut-off valve 29, and the fourth reaction furnace outlet cut-off valve 31 are opened, and the remaining valves are closed, so that the nitrogen enters the second reaction furnace 2 first, and then passes through the third reaction furnace 3 and the fourth reaction furnace 4 in turn, and finally the nitrogen after absorbing heat is sent to the flare at the outlet of the fourth reaction furnace 4.
[0035] If the third reaction furnace 3 needs to be repaired and the catalyst bed, then the nitrogen connecting pipeline hand valve 43, the third reaction furnace heating inlet valve 20, the third reaction furnace outlet cut-off valve 29, and the fourth reaction furnace outlet cut-off valve 31 are opened, and the remaining valves are closed, so that the nitrogen enters the third reaction furnace 3 first, and then passes through the fourth reaction furnace 4, and finally the nitrogen after absorbing heat is sent to the flare at the outlet of the fourth reaction furnace 4.
[0036] If the fourth reactor 4 needs to be maintained and the catalyst bed is to be treated, the nitrogen connecting pipeline hand valve 43, the fourth reactor temperature rising inlet valve 21 and the fourth reactor outlet cut-off valve 31 are opened, and the remaining valves are closed, so that nitrogen is first introduced into the fourth reactor 4, then passes through the fourth reactor 4, and finally the nitrogen after absorbing heat is sent to the flare at the outlet of the fourth reactor 4.
[0037] The above description is only an example for clearly illustrating the present application, and is not a limitation on the embodiments of the present application. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.
Claims
1. A method for cooling the catalyst bed in a reactor of a methane synthesis unit, characterized in that: This includes adding a first manual valve for demineralized water supply on the inlet pipeline side of the circulating compressor inlet boiler water heat exchanger; adding a figure-eight blind flange for the demineralized water supply pipeline on the inlet pipeline side of the circulating compressor inlet boiler water heat exchanger; adding a second manual valve for demineralized water supply on the inlet pipeline side of the circulating compressor inlet boiler water heat exchanger; adding a first manual valve for demineralized water return on the outlet pipeline side of the circulating compressor inlet boiler water heat exchanger; adding a figure-eight blind flange for the demineralized water return pipeline on the outlet pipeline side of the circulating compressor inlet boiler water heat exchanger; adding a second manual valve for demineralized water return on the outlet pipeline side of the circulating compressor inlet boiler water heat exchanger; and installing a connecting pipeline on the medium-pressure nitrogen pipeline that connects to the heating pipeline, with a nitrogen connection pipeline manual valve and a nitrogen connection pipeline check valve installed on the connecting pipeline. A manual valve for the circulating compressor inlet water supply pipeline of the boiler water heat exchanger is installed on the boiler water heat exchanger inlet pipeline, and a manual valve for the circulating compressor inlet water return pipeline of the boiler water heat exchanger is installed on the boiler water heat exchanger outlet pipeline. At the start of the first cooling stage, the original boiler water pipeline is shut down and the newly added demineralized water pipeline is put into operation. Then, the top of the boiler water heat exchanger shell side is vented to allow the demineralized water to flow continuously in the boiler water heat exchanger. At the same time, the temperature of the heat exchange water in the boiler water heat exchanger shell side is reduced from 250°C of boiler water to 50°C of demineralized water, which reduces the temperature of the process gas entering the inlet cooler of the circulating compressor and accelerates the cooling rate of the first cooling stage. At the beginning of the second cooling stage, close the medium-pressure nitrogen manual valve and open the nitrogen connection pipeline manual valve to introduce medium-pressure nitrogen. At this time, the nitrogen can enter the reactor without being heated by the No. 1 and No. 2 raw material gas heat exchangers.
2. The method for cooling the catalyst bed in the reactor of a methane synthesis unit as described in claim 1, characterized in that: During the first cooling stage, the boiler water used in the boiler water heat exchanger was changed to the demineralized water used in the demineralized water heat exchanger at the outlet of reactor No. 4, and the demineralized water supply from the demineralized water heat exchanger at the outlet of reactor No. 4 was connected to the boiler water supply pipeline of the boiler water heat exchanger.
3. The method for cooling the catalyst bed in the reactor of a methane synthesis unit as described in claim 1, characterized in that: In the second cooling stage, the nitrogen inlet in the methane synthesis unit is changed to the pipeline before the check valve in front of the heating inlet valve of the desulfurization tank.
Citation Information
Patent Citations
Catalyst bed layer cooling structure in reaction furnace of methane synthesis device
CN218573618U