Device for recovering liquid nitrogen wash tail gas by using methanol synthesis system
By designing a device that uses a methanol synthesis system to recover liquid nitrogen to wash exhaust gas, the problems of waste of CO resources and carbon emissions in exhaust gas are solved, and the effective recycling and utilization of exhaust gas is achieved, reducing carbon emissions and saving production costs.
Patent Information
- Application Number
- CN202421218012.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-30
- Publication Date
- 2025-03-14
- Estimated Expiration
- 2034-05-30
AI Technical Summary
During the existing liquid nitrogen washing exhaust gas treatment process, CO resources in the exhaust gas are seriously wasted, and combustion aggravates carbon emissions, making it impossible to effectively utilize exhaust gas.
Design a device to recover liquid nitrogen and wash the exhaust gas using a methanol synthesis system, adjust the exhaust gas through a reheater and a pressure temperature conversion unit to meet the process requirements of the methanol synthesis system, and mix it with the purified gas to reduce the CO content.
It realizes effective recycling and utilization of liquid nitrogen washing exhaust gas, reduces carbon emissions, meets the raw material gas requirements of the methanol synthesis system, and saves the production costs of methanol and transformed synthesis gas.
Smart Images
Figure CN222606327U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of liquid nitrogen tail gas recovery, in particular to a device for recovering liquid nitrogen tail gas from a methanol synthesis system. Background Art
[0002] The existing liquid nitrogen washing device (abbreviated as: liquid nitrogen washing) uses liquid nitrogen to wash CO, Ar, CH4 and other components in the raw gas in the nitrogen washing tower, separates them in the hydrogen separator, and recycles the hydrogen after flashing. The temperature of the separated liquid is -190°C. After the raw gas and normal temperature nitrogen are reheated, the temperature reaches about 20°C, and the gas volume is about 2000m3 / h, which is used as tail gas to be flared and vented. The above process is a conventional liquid nitrogen washing tail gas treatment process, which increases carbon emissions through torch combustion and also causes a large amount of CO resource waste. Through the analysis of the tail gas components, it can be known that its CO is 50%, H2 3%, and N2 45%. If CO is purified, the CO in the tail gas is too low, and if it is used as fuel gas, the calorific value is too low. Therefore, how to realize the utilization of liquid nitrogen washing tail gas to reduce carbon emissions has become a technical problem that needs to be solved urgently. Utility Model Content
[0003] The utility model aims to provide a device for washing tail gas by recycling liquid nitrogen from a methanol synthesis system, so as to solve the problems raised in the above-mentioned background technology.
[0004] In order to achieve the above purpose, the utility model provides the following technical solutions:
[0005] A device for washing tail gas by recycling liquid nitrogen from a methanol synthesis system comprises a liquid nitrogen washing device arranged in a cold box, the tail gas outlet of the liquid nitrogen washing device is connected to a first flare device through a recuperator and a first control valve, a first tee is arranged between the first control valve and the first flare device, the third end of the first tee is connected to an inlet of an oil-gas separator through a pressure-temperature conversion unit, the outlet of the oil-gas separator is connected to the methanol synthesis system; the inlet of the oil-gas separator is also connected to a purified gas pipeline.
[0006] The utility model has the following beneficial effects: by adjusting the pressure and temperature of the reheated liquid nitrogen washed tail gas, the tail gas meets the process requirements of the methanol synthesis system; and at the same time, the tail gas enters the oil-gas separator, and is mixed with the purified gas from the purified gas pipeline while the oil-gas separation is performed, so as to reduce the CO content in the mixed gas to 1.5-2.0%, so as to meet the requirements of the methanol synthesis system for the carbon monoxide content; the utility model has the characteristics of being able to effectively recover the liquid nitrogen washed tail gas and reduce carbon emissions.
[0007] As a further technical solution of the utility model, the pressure-temperature conversion unit includes at least an exhaust gas compressor connected to the third end of the first tee, and the outlet of the exhaust gas compressor is connected to the exhaust gas cooler; a second tee is provided between the outlet of the exhaust gas compressor and the exhaust gas cooler, and the third end of the second tee is connected to the second flare device through a second flare valve.
[0008] As a further technical solution of the utility model, a third tee is provided at the inlet end of the exhaust gas cooler, a fourth tee is provided at the outlet end of the exhaust gas cooler, a shortcut pipe with a second control valve is provided between the third end of the third tee and the third end of the fourth tee; a cooler inlet valve is provided between the inlet end of the exhaust gas cooler and the third tee, and a cooler outlet valve is provided between the outlet end of the exhaust gas cooler and the fourth tee.
[0009] As a further technical solution of the utility model, a fifth tee is provided between the second tee and the exhaust gas cooler, and the third end of the fifth tee is connected to the outlet of the conversion separator; the inlet of the conversion separator is connected to the raw gas pipeline, and the outlet of the conversion separator is connected to the conversion device system.
[0010] As a further technical solution of the utility model, a third control valve is provided between the third end of the fifth three-way connection and the outlet of the conversion separator, and a fourth control valve is provided between the fifth three-way connection and the exhaust gas cooler.
[0011] As a further technical solution of the utility model, the pressure-temperature conversion unit is further provided with a nitrogen replacement component for nitrogen replacement of the pipeline; the nitrogen replacement component includes a nitrogen access pipe arranged at the outlet of the exhaust gas compressor, and the nitrogen access pipe is provided with a nitrogen inlet valve; a first nitrogen exhaust pipe with a first nitrogen outlet valve is provided at the connection between the pressure-temperature conversion unit and the conversion separator, and a second nitrogen exhaust pipe with a second nitrogen outlet valve is provided at the connection between the pressure-temperature conversion unit and the oil-gas separator.
[0012] As a further technical solution of the utility model, a first flare valve is provided between the first flare device and the first three-way connection.
[0013] As a further technical solution of the utility model, a flow sensor is provided between the second tee and the fifth tee.
[0014] As a further technical solution of the utility model, a first pressure sensor is provided between the third tee and the cooler inlet valve, a temperature sensor is provided between the cooler outlet valve and the fourth tee, and a CO online analyzer and a second pressure sensor are provided between the fourth tee and the inlet of the oil-gas separator.
[0015] According to the above scheme, a device for recovering liquid nitrogen washing tail gas from a methanol synthesis system is manufactured. By setting a pressure-temperature conversion unit, the pressure and temperature of the reheated liquid nitrogen washing tail gas are changed to meet the process requirements of the methanol synthesis system. At the same time, the liquid nitrogen washing tail gas is mixed with the purified gas from the purified gas pipeline in the oil-gas separator, thereby achieving the purpose of reducing the carbon monoxide content, so that the liquid nitrogen washing tail gas can be used as a raw material to enter the methanol synthesis system for producing methanol; further, when the amount of liquid nitrogen washing tail gas is large, it can be mixed with the raw coal gas from the conversion separator and enter the conversion device to be used as a raw material for synthesizing conversion gas; the above process has the advantages of reducing carbon emissions, turning liquid nitrogen washing tail gas into treasure, and saving the production costs of methanol and conversion synthesis gas. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a schematic diagram of the overall structure of the utility model.
[0017] In the figure: 1, liquid nitrogen washing device; 2, recuperator; 3, first control valve; 4, first flare device; 5, first three-way valve; 6, oil-gas separator; 7, self-purifying gas pipeline; 8, tail gas compressor; 9, tail gas cooler; 10, second three-way valve; 11, second flare valve; 12, second flare device; 13, third three-way valve; 14, fourth three-way valve; 15, second control valve; 16, cooler inlet valve; 17, cooler outlet valve; 18, fifth three-way valve 1 ; 19. conversion separator; 20. raw gas pipeline; 21. conversion device system; 22. third control valve; 23. fourth control valve; 24. nitrogen access pipe; 25. nitrogen inlet valve; 26. first nitrogen outlet valve; 27. second nitrogen outlet valve; 28. flow sensor; 29. first pressure sensor; 30. temperature sensor; 31. CO online analyzer; 32. second pressure sensor; 33. methanol synthesis system; 34. first flare valve. DETAILED DESCRIPTION
[0018] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0019] like Figure 1As shown, the utility model is a device for washing tail gas by recycling liquid nitrogen from a methanol synthesis system, comprising a liquid nitrogen washing device 1 arranged in a cold box, the tail gas outlet of the liquid nitrogen washing device 1 is connected to a first flare device 4 through a recuperator 2 and a first control valve 3, a first tee 5 is arranged between the first control valve 3 and the first flare device 4, the third end of the first tee 5 is connected to an inlet of an oil-gas separator 6 through a pressure-temperature conversion unit, and the outlet of the oil-gas separator 6 is connected to a methanol synthesis system 33;
[0020] The inlet of the oil-gas separator 6 is also connected to the purified gas pipeline 7. The utility model recovers and reuses the reheated liquid nitrogen washed tail gas by setting a pressure-temperature conversion unit, and mixes the reheated liquid nitrogen washed tail gas with the purified gas from the purified gas pipeline 7 through the oil-gas separator 6 to achieve the purpose of reducing the CO content and meeting the process requirements of the methanol synthesis system 33. The above method can realize the recovery and reuse of the liquid nitrogen washed tail gas to achieve the characteristics of reducing carbon emissions under the premise of reducing the cost of methanol synthesis.
[0021] Furthermore, the pressure-temperature conversion unit at least includes an exhaust gas compressor 8 connected to the third end of the first tee 5, and the outlet of the exhaust gas compressor 8 is connected to the exhaust gas cooler 9; a second tee 10 is provided between the outlet of the exhaust gas compressor 8 and the exhaust gas cooler 9, and the third end of the second tee 10 is connected to the second flare device 12 through a second flare valve 11. The pressure-temperature conversion unit described in the utility model at least includes an exhaust gas compressor 8 for adjusting the pressure of the liquid nitrogen-washed exhaust gas, an exhaust gas cooler 9 for adjusting the temperature of the liquid nitrogen-washed exhaust gas, and a second flare device 12 for emergency venting during the start-up phase or when a related system fails; the above-mentioned settings can achieve adjustment of the pressure and temperature of the liquid nitrogen-washed exhaust gas, thereby ensuring long-term stable operation of the system.
[0022] Furthermore, the inlet end of the tail gas cooler 9 is provided with a third tee 13, the outlet end of the tail gas cooler 9 is provided with a fourth tee 14, a shortcut pipeline with a second control valve 15 is provided between the third end of the third tee 13 and the third end of the fourth tee 14; a cooler inlet valve 16 is provided between the inlet end of the tail gas cooler 9 and the third tee 13, and a cooler outlet valve 17 is provided between the outlet end of the tail gas cooler 9 and the fourth tee 14. The above arrangement enables the emergency supply of liquid nitrogen to wash tail gas to the methanol synthesis system 33 through the shortcut pipeline with the second control valve 15 when the tail gas cooler 9 fails, thereby ensuring the long-term stable operation of the entire system.
[0023] Furthermore, a fifth tee 18 is provided between the second tee 10 and the tail gas cooler 9, and the third end of the fifth tee 18 is connected to the outlet of the conversion separator 19; the inlet of the conversion separator 19 is connected to the raw gas pipeline 20, and the outlet of the conversion separator 19 is connected to the conversion device system 21. The above arrangement enables further utilization of the liquid nitrogen washing tail gas, especially when a part of the liquid nitrogen washing tail gas is supplied to the methanol synthesis system 33, and the amount of the liquid nitrogen washing tail gas is still too large, the part of the liquid nitrogen washing tail gas can be sent to the conversion separator 19, and after being mixed with the raw gas from the conversion separator 19, it enters the conversion device system 21, so as to achieve further utilization of the liquid nitrogen washing.
[0024] Furthermore, a third control valve 22 is provided between the third end of the fifth three-way valve 18 and the outlet of the conversion separator 19 , and a fourth control valve 23 is provided between the fifth three-way valve 18 and the exhaust gas cooler 9 .
[0025] Furthermore, the pressure-temperature conversion unit is also provided with a nitrogen replacement part for nitrogen replacement of the pipeline; the nitrogen replacement part includes a nitrogen access pipe 24 arranged at the outlet of the tail gas compressor 8, and a nitrogen inlet valve 25 is arranged on the nitrogen access pipe 24; a first nitrogen exhaust pipe with a first nitrogen outlet valve 26 is arranged at the connection between the pressure-temperature conversion unit and the conversion separator 19, and a second nitrogen exhaust pipe with a second nitrogen outlet valve 27 is arranged at the connection between the pressure-temperature conversion unit and the oil-gas separator 6. The above arrangement can realize the replacement of the gas inside the pipeline in the pressure-temperature conversion unit, thereby avoiding the introduction of impurities and affecting the quality of subsequent products.
[0026] Furthermore, a first flare valve 34 is provided between the first flare device 4 and the first three-way valve 5 .
[0027] Furthermore, a flow sensor 28 is provided between the second tee 10 and the fifth tee 18 .
[0028] Furthermore, a first pressure sensor 29 is provided between the third three-way valve 13 and the cooler inlet valve 16, a temperature sensor 30 is provided between the cooler outlet valve 17 and the fourth three-way valve 14, and a CO online analyzer 31 and a second pressure sensor 32 are provided between the fourth three-way valve 14 and the inlet of the oil-gas separator 6.
[0029] The working principle of the utility model is as follows: the utility model first performs nitrogen replacement before use, and the nitrogen replacement can be for the relevant pipelines from the pressure temperature conversion unit to the oil-gas separator 6, or for the relevant pipelines from the pressure temperature conversion unit to the conversion separator 19; or the above two pipelines are all replaced with nitrogen. During the replacement process, the nitrogen access pipe 24 is connected to the nitrogen pipe network (or the nitrogen storage tank), and the nitrogen inlet valve 25, the first nitrogen outlet valve 26 and the second nitrogen outlet valve 27 are opened to realize the replacement of nitrogen; after the nitrogen replacement, the above corresponding valves can be closed; during the initial operation, the tail gas volume in the liquid nitrogen washing device 1 is about 2000m 3 / h, the composition is CO 50%, H2 3%. N2 45%, the pressure is 0.6MPa; after being reheated by the reheater 2, the temperature is about 20℃; first, the first flare device 4 and the tail gas cooler 9 are turned on, so that the tail gas in the liquid nitrogen washing device 1 enters the first flare device 4 at a normal flow rate and burns, and the circulating water passes through the tail gas cooler 9 to gradually preheat it, and determine whether the tail gas cooler 9 is operating normally; when the tail gas cooler 9 cannot operate normally, the shortcut pipeline is enabled; when it can operate normally, the tail gas compressor 8 is started, the first flare valve 34 is gradually closed, and the second flare valve 11 is opened. Observe the operation of the tail gas compressor 8. After the tail gas compressor 8 runs stably, open the fourth control valve 23, and close the first torch valve 34 and the second torch valve 11, so that the liquid nitrogen-washed tail gas passing through the tail gas compressor 8 enters the tail gas cooler 9 for heat exchange (the tail gas pressure after passing through the tail gas compressor 8 is 6.5-7.5MPa and the temperature is 160°C; the temperature after passing through the tail gas cooler 9 is 30°C). After the above heat exchange, the cooled tail gas enters the oil-gas separator 6 at a pressure of 5.0MPa and is heated with the purified gas from the purified gas pipeline 7. The mixed gas has a CO content of 1.5%-2.0%, and enters the methanol synthesis system 33 for producing methanol; when the amount of tail gas in the liquid nitrogen washing device 1 is too large, the third control valve 22 is opened to allow the gas compressed by the tail gas compressor 8 to enter the outlet of the conversion separator 19 and mix with the raw coal gas from the conversion separator 19, and then be sent to the conversion device system 21 for producing conversion gas; when the conversion device system 21 and the methanol synthesis system 33 are stopped, they can be vented through the first flare device 4; the corresponding instruments in the utility model (such as: flow sensor 28, first pressure sensor 29, temperature sensor 30, CO online analyzer 31, etc., are used to monitor the flow, pressure, temperature and content of the tail gas, so as to realize timely adjustment of the corresponding process technology and ensure long-term stable operation of the system.) The utility model has a reasonable design, based on the characteristics of liquid nitrogen washing tail gas and the process requirements in the conversion device system 21 and the methanol synthesis system 33, the above three are coupled to achieve the purpose of reducing carbon emissions and saving raw material costs.
[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A device for washing tail gas by recovering liquid nitrogen from a methanol synthesis system, comprising a liquid nitrogen washing device (1) arranged in a cold box, wherein the tail gas outlet of the liquid nitrogen washing device (1) is connected to a first flare device (4) via a recuperator (2) and a first control valve (3), and characterized in that: A first tee (5) is provided between the first control valve (3) and the first flare device (4), a third end of the first tee (5) is connected to the inlet of an oil-gas separator (6) through a pressure-temperature conversion unit, and an outlet of the oil-gas separator (6) is connected to a methanol synthesis system (33); The inlet of the oil-gas separator (6) is also connected to the purified gas pipeline (7).
2. The device for recovering liquid nitrogen from a methanol synthesis system for washing tail gas according to claim 1, characterized in that: The pressure-temperature conversion unit at least comprises an exhaust gas compressor (8) connected to the third end of the first three-way connection (5), and the outlet of the exhaust gas compressor (8) is connected to an exhaust gas cooler (9); A second tee (10) is provided between the outlet of the exhaust gas compressor (8) and the exhaust gas cooler (9), and a third end of the second tee (10) is connected to a second flare device (12) via a second flare valve (11).
3. The device for recovering liquid nitrogen from a methanol synthesis system for washing tail gas according to claim 2, characterized in that: The inlet end of the exhaust gas cooler (9) is provided with a third tee (13), the outlet end of the exhaust gas cooler (9) is provided with a fourth tee (14), and a shortcut pipeline with a second control valve (15) is provided between the third end of the third tee (13) and the third end of the fourth tee (14); A cooler inlet valve (16) is provided between the inlet end of the exhaust gas cooler (9) and the third three-way valve (13), and a cooler outlet valve (17) is provided between the outlet end of the exhaust gas cooler (9) and the fourth three-way valve (14).
4. The device for recovering liquid nitrogen from a methanol synthesis system for washing tail gas according to claim 2, characterized in that: A fifth tee (18) is provided between the second tee (10) and the exhaust gas cooler (9), and a third end of the fifth tee (18) is connected to the outlet of the conversion separator (19); The inlet of the conversion separator (19) is connected to the raw gas pipeline (20), and the outlet of the conversion separator (19) is connected to the conversion device system (21).
5. The device for recovering liquid nitrogen from a methanol synthesis system for washing tail gas according to claim 4, characterized in that: A third control valve (22) is provided between the third end of the fifth tee (18) and the outlet of the conversion separator (19), and a fourth control valve (23) is provided between the fifth tee (18) and the exhaust gas cooler (9).
6. The device for recovering liquid nitrogen from a methanol synthesis system for washing tail gas according to claim 5, characterized in that: The pressure-temperature conversion unit is also provided with a nitrogen replacement component for replacing nitrogen in the pipeline; The nitrogen replacement component comprises a nitrogen inlet pipe (24) arranged at the outlet of the exhaust gas compressor (8), and a nitrogen inlet valve (25) is arranged on the nitrogen inlet pipe (24); a first nitrogen exhaust pipe with a first nitrogen outlet valve (26) is arranged at the connection between the pressure and temperature conversion unit and the conversion separator (19), and a second nitrogen exhaust pipe with a second nitrogen outlet valve (27) is arranged at the connection between the pressure and temperature conversion unit and the oil and gas separator (6).
7. The device for recovering liquid nitrogen from a methanol synthesis system for washing tail gas according to claim 1, characterized in that: A first flare valve (34) is provided between the first flare device (4) and the first three-way valve (5).
8. The device for recovering liquid nitrogen from a methanol synthesis system for washing tail gas according to claim 4, characterized in that: A flow sensor (28) is provided between the second tee (10) and the fifth tee (18).
9. The device for recovering liquid nitrogen from a methanol synthesis system for washing tail gas according to claim 3, characterized in that: A first pressure sensor (29) is provided between the third three-way valve (13) and the cooler inlet valve (16), a temperature sensor (30) is provided between the cooler outlet valve (17) and the fourth three-way valve (14), and a CO online analyzer (31) and a second pressure sensor (32) are provided between the fourth three-way valve (14) and the inlet of the oil-gas separator (6).