Low-temperature methanol washing system for recycling effective gas in 0.8 MPa sulfur-rich methanol

Abstract

The utility model relates to a low-temperature methanol washing system for recycling effective gas in 0.8 MPa sulfur-rich methanol. The low-temperature methanol washing system comprises a 0.4 MPa sulfur-rich methanol flash tank and a second compressor, the liquid inlet end of the 0.4 MPa sulfur-rich methanol flash tank is communicated with the liquid outlet end of the 0.8 MPa carbon-rich methanol flash tank of the low-temperature methanol washing system body, the gas outlet end of the 0.4 MPa sulfur-rich methanol flash tank is communicated with the inlet end of the second compressor, and the outlet end of the second compressor is communicated with the raw gas inlet end of the main washing tower of the low-temperature methanol washing system body; and the liquid outlet end of the 0.4 MPa sulfur-rich methanol flash tank is communicated with the liquid inlet end of the 0.2 MPa flash tower of the low-temperature methanol washing system body. The system improves the effective gas recovery rate of the low-temperature methanol washing process, reduces the comprehensive energy consumption of a production device, and improves the economical efficiency of the low-temperature methanol washing device; the overtemperature risk of a subsequent heat accumulating type oxidation device is reduced; and meanwhile, the flash evaporation load of a 0.2 MPa flash evaporation tower is reduced, and the flash evaporation effect is improved, so that the load of a subsequent methanol regeneration system is reduced.

Description

Technical Field

[0001] This utility model relates to the field of coal chemical technology, specifically to a low-temperature methanol washing system for the reuse of effective gas in 0.8MPa sulfur-rich methanol. Background Technology

[0002] In the field of coal chemical technology, crude coal gas purification typically employs a low-temperature methanol washing unit. This unit utilizes the principle that methanol has varying absorption capacities for dissolving and absorbing acidic gases (such as hydrogen sulfide and carbon dioxide) to refine the crude coal gas. Cold methanol also has the ability to absorb methane, carbon monoxide, and hydrogen (hereinafter referred to as effective gases) in the crude coal gas. Although the absorption capacity is relatively small, due to the large circulation volume of cold methanol, its low temperature, and the high pressure of the main absorption tower, some of the effective gases in the syngas will still be dissolved and absorbed by methanol and enter the regeneration system. This portion of effective gases will be discharged from the unit along with methanol-rich vapor (methanol after absorbing acidic gases) during the methanol regeneration process.

[0003] Currently, existing low-temperature methanol washing systems (such as...) Figure 2 As shown, because 0.8MPa sulfur-rich methanol, compared to 0.8MPa carbon-rich methanol, does not undergo 0.4MPa flash evaporation treatment before entering the 0.2MPa flash tower, the effective gas in the 0.8MPa sulfur-rich methanol is not recovered and utilized. As a result, most of the effective gas in the 0.8MPa sulfur-rich methanol flashes out in the subsequent 0.2MPa flash tower, resulting in a high content of effective gas components and calorific value in the 0.2MPa methanol flash vapor. This can easily lead to overheating of the device during the combustion process in the regenerative oxidation unit.

[0004] In addition, due to the high content of effective gas components in the 0.2MPa methanol-rich flash vapor, the effective gas loss is large, resulting in increased overall energy consumption and reduced economic efficiency of the low-temperature methanol washing unit.

[0005] Furthermore, since the 0.8MPa sulfur-rich methanol enters the 0.2MPa flash tower without undergoing 0.4MPa flash treatment, most of the effective gas in the 0.8MPa sulfur-rich methanol needs to be flashed out directly in the subsequent 0.2MPa flash tower, resulting in a large flash load on the 0.2MPa flash tower. This can easily lead to incomplete flashing of the rich methanol and increase the load on the subsequent methanol regeneration system. Utility Model Content

[0006] The technical problem to be solved by this utility model is to provide a low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol, so as to overcome the shortcomings of the prior art.

[0007] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: a low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol, including a low-temperature methanol washing system body, a 0.4MPa sulfur-rich methanol flash tank and a second compressor.

[0008] The liquid inlet of the 0.4MPa sulfur-rich methanol flash tank is connected to the liquid outlet of the 0.8MPa carbon-rich methanol flash tank of the low-temperature methanol washing system. The gas outlet of the 0.4MPa sulfur-rich methanol flash tank is connected to the inlet of the second compressor. The outlet of the second compressor is connected to the crude gas inlet of the main washing tower of the low-temperature methanol washing system. The liquid outlet of the 0.4MPa sulfur-rich methanol flash tank is connected to the liquid inlet of the 0.2MPa flash tower of the low-temperature methanol washing system.

[0009] The beneficial effects of this invention are as follows: This system uses a 0.4MPa sulfur-rich methanol flash tank to flash 0.8MPa sulfur-rich methanol at 0.4MPa. The second compressor pressurizes the 0.4MPa sulfur-rich methanol flash vapor to 3.2MPa and sends it to the crude gas inlet of the main washing tower for reuse, thereby achieving the recovery of effective gas from the 0.8MPa sulfur-rich methanol. This system improves the effective gas recovery rate of the low-temperature methanol washing process, reduces the overall energy consumption of the production unit, and improves the economic efficiency of the low-temperature methanol washing unit. Because the effective gas components in the 0.2MPa flash vapor are reduced, the calorific value of the 0.2MPa flash vapor decreases, reducing the risk of overheating in the subsequent regenerative oxidation unit. At the same time, it also reduces the flash load of the 0.2MPa flash tank, improves the flash effect, and thus reduces the load on the subsequent methanol regeneration system.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, a third liquid level control valve is installed on the pipeline between the liquid outlet end of the 0.4MPa sulfur-rich methanol flash tank and the liquid inlet end of the 0.2MPa flash tower.

[0012] Furthermore, the liquid outlet of the 0.4MPa sulfur-rich methanol flash tank is connected to an emergency discharge pipeline, and an discharge control valve is installed on the emergency discharge pipeline.

[0013] Furthermore, the 0.4MPa sulfur-rich methanol flash tank is equipped with a second level gauge to detect the internal liquid level. The second level gauge is connected to the signal of the third level control valve and the discharge control valve.

[0014] Furthermore, a second level control valve is installed on the pipeline between the liquid inlet end of the 0.4MPa sulfur-rich methanol flash tank and the liquid outlet end of the 0.8MPa sulfur-rich methanol flash tank of the low-temperature methanol washing system body. The second level control valve, the first level gauge of the low-temperature methanol washing system body, and the first level control valve of the low-temperature methanol washing system body are connected by a signal.

[0015] Furthermore, a running detection signal transmitter is installed at the second compressor to detect its operating status, and the running detection signal transmitter is connected to the signal of the second liquid level control valve.

[0016] Furthermore, the gas outlet of the 0.4MPa sulfur-rich methanol flash tank is connected to the regenerative oxidation unit of the cryogenic methanol washing system via a pipeline. A pressure transmitter and a pressure control valve are sequentially installed on the pipeline at the gas outlet of the 0.4MPa sulfur-rich methanol flash tank, and the pressure transmitter and the pressure control valve are connected by a signal.

[0017] Furthermore, a bypass valve and a manual valve are connected in parallel between the pressure transmitter and the pressure control valve, and the other end of the bypass valve and the manual valve is connected to a safety valve.

[0018] Furthermore, a wire mesh demister is installed at the top of the 0.4 MPa sulfur-rich methanol flash tank. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the system structure of this utility model;

[0020] Figure 2 This is a schematic diagram of the existing technology.

[0021] The attached diagram lists the components represented by each number as follows:

[0022] 1. Main washing tower; 2. 0.8MPa carbon-rich methanol flash tank; 3. 0.8MPa sulfur-rich methanol flash tank; 4. First compressor; 5. 0.4MPa carbon-rich methanol flash tank; 6. 0.2MPa flash tower; 7. Regenerative oxidizer; 8. First level gauge; 9. First level control valve; 10. Second level control valve; 11. 0.4MPa sulfur-rich methanol flash tank; 12. Wire mesh demister; 13. Second level gauge; 14. Third level control valve; 15. Discharge control valve; 16. Second compressor; 17. Pressure transmitter; 18. Pressure control valve; 19. Bypass valve; 20. Manual valve; 21. Safety valve; 22. Operation detection signal transmitter. Detailed Implementation

[0023] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0024] like Figure 1 As shown in Example 1, a low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol includes a low-temperature methanol washing system body, a 0.4MPa sulfur-rich methanol flash tank 11, and a second compressor 16.

[0025] The liquid inlet of the 0.4MPa sulfur-rich methanol flash tank 11 is connected to the liquid outlet of the 0.8MPa carbon-rich methanol flash tank 2 of the low-temperature methanol washing system. The gas outlet of the 0.4MPa sulfur-rich methanol flash tank 11 is connected to the inlet of the second compressor 16. The outlet of the second compressor 16 is connected to the crude gas inlet of the main washing tower 1 of the low-temperature methanol washing system. The liquid outlet of the 0.4MPa sulfur-rich methanol flash tank 11 is connected to the liquid inlet of the 0.2MPa flash tower 6 of the low-temperature methanol washing system.

[0026] This system uses a 0.4MPa sulfur-rich methanol flash evaporator 11 to flash 0.8MPa sulfur-rich methanol at 0.4MPa. The second compressor 16 pressurizes the 0.4MPa sulfur-rich methanol flash vapor to 3.2MPa and sends it to the crude gas inlet of the main washing tower 1 for reuse, thus achieving the recovery of effective gas from the 0.8MPa sulfur-rich methanol. This system improves the effective gas recovery rate of the low-temperature methanol washing process, reduces the overall energy consumption of the production unit, and improves the economic efficiency of the low-temperature methanol washing unit. Because the effective gas components in the 0.2MPa flash vapor are reduced, the calorific value of the 0.2MPa flash vapor decreases, reducing the risk of overheating in the subsequent regenerative oxidation unit 7. Simultaneously, it reduces the flash load on the 0.2MPa flash evaporator 6, improving the flash evaporation effect and thus reducing the load on the subsequent methanol regeneration system.

[0027] Example 2 is a further improvement based on Example 1, and its details are as follows:

[0028] A third liquid level control valve 14 is installed on the pipeline between the liquid outlet end of the 0.4MPa sulfur-rich methanol flash tank 11 and the liquid inlet end of the 0.2MPa flash tower 6.

[0029] A third liquid level control valve 14 is set up. When the liquid level alarm of the 0.4MPa sulfur-rich methanol flash tank 11 is high, the third liquid level control valve 14 is opened wide. When the liquid level alarm of the 0.4MPa sulfur-rich methanol flash tank 11 is low, the third liquid level control valve 14 is closed to ensure that the liquid level of the 0.4MPa sulfur-rich methanol flash tank 11 is within the normal range.

[0030] Example 3 is a further improvement based on Example 2, and its details are as follows:

[0031] An emergency discharge pipeline is connected to the liquid outlet end of the 0.4MPa sulfur-rich methanol flash tank 11, and an discharge control valve 15 is installed on the emergency discharge pipeline.

[0032] If the liquid level remains within the high alarm range after the third liquid level control valve 14 is fully opened, the discharge control valve 15 will be opened to discharge methanol in an emergency, ensuring that the liquid level in the 0.4MPa sulfur-rich methanol flash tank 11 is within the normal range.

[0033] Example 4 is a further improvement on Example 3, and its details are as follows:

[0034] A second level gauge 13 is installed on the 0.4MPa sulfur-rich methanol flash tank 11 to detect the internal liquid level. The second level gauge 13 is connected to the third level control valve 14 and the discharge control valve 15. Monitoring the liquid level of the 0.4MPa sulfur-rich methanol flash tank 11 and setting high and low level alarms allows for adjustment of the liquid level in the 0.4MPa sulfur-rich methanol flash tank 11 according to actual conditions.

[0035] Example 5 is a further improvement based on Example 1, and its details are as follows:

[0036] A second level control valve 10 is installed on the pipeline between the liquid inlet end of the 0.4MPa sulfur-rich methanol flash tank 11 and the liquid outlet end of the 0.8MPa sulfur-rich methanol flash tank 3 of the low-temperature methanol washing system body. The second level control valve 10, the first level gauge 8 of the low-temperature methanol washing system body, and the first level control valve 9 of the low-temperature methanol washing system body are connected by a signal.

[0037] 0.8MPa sulfur-rich methanol is introduced into 0.4MPa sulfur-rich methanol flash tank 11 through the second liquid level control valve 10. At this time, the liquid level of 0.8MPa sulfur-rich methanol flash tank 3 is jointly controlled by the first liquid level control valve 9 and the second liquid level control valve 10 of the low-temperature methanol washing system body;

[0038] When the high liquid level alarm of the 0.8MPa sulfur-rich methanol flash tank 3 is triggered, the second liquid level control valve 10 is opened first. If the liquid level continues to rise after the second liquid level control valve 10 is fully opened, the first liquid level control valve 9 is opened.

[0039] When the liquid level alarm is triggered in the 0.8MPa sulfur-rich methanol flash tank 3, the first liquid level control valve 9 is closed first. If the liquid level is still low after the first liquid level control valve 9 is completely closed, the second liquid level control valve 10 is closed further. The above operation can ensure that the liquid level in the 0.8MPa sulfur-rich methanol flash tank 3 is within the normal range, while maximizing the flow rate of 0.8MPa sulfur-rich methanol into the 0.4MPa sulfur-rich methanol flash tank 11, thereby maximizing the recovery of effective gas in the 0.8MPa sulfur-rich methanol.

[0040] Example 6 is a further improvement on Example 5, and its details are as follows:

[0041] The second compressor 16 is equipped with a running detection signal transmitter 22 to detect its operating status. The running detection signal transmitter 22 is connected to the second liquid level control valve 10.

[0042] A running detection signal transmitter 22 is installed in the second compressor 16. When the second compressor 16 is detected to be shut down, the second liquid level control valve 10 is interlocked and shut off the 0.8MPa sulfur-rich methanol flash evaporation system.

[0043] Example 7 is a further improvement based on Example 1, and its details are as follows:

[0044] The gas outlet end of the 0.4MPa sulfur-rich methanol flash tank 11 is connected to the regenerative oxidation device 7 of the low-temperature methanol washing system body through a pipeline. A pressure transmitter 17 and a pressure control valve 18 are sequentially installed on the pipeline at the gas outlet end of the 0.4MPa sulfur-rich methanol flash tank 11. The pressure transmitter 17 and the pressure control valve 18 are connected by a signal.

[0045] A pressure transmitter 17 is installed in the 0.4MPa sulfur-rich methanol flash tank 11 to monitor the pressure of the 0.4MPa sulfur-rich methanol flash tank 11 and set a high alarm. A pressure control valve 18 is installed so that when the pressure of the 0.4MPa sulfur-rich methanol flash tank 11 reaches the high alarm value, the pressure control valve 18 is opened to discharge the 0.4MPa sulfur-rich methanol flash vapor into the regenerative oxidation device 7 of the low-temperature methanol washing system, thereby controlling the pressure of the 0.4MPa sulfur-rich methanol flash tank 11 within the normal range.

[0046] Example 8 is a further improvement on Example 7, and its details are as follows:

[0047] A bypass valve 19 and a manual valve 20 are connected in parallel between the pressure transmitter 17 and the pressure control valve 18. The other end of the bypass valve 19 and the manual valve 20 is connected to the safety valve 21.

[0048] A safety valve 21, a manual valve 20, and a bypass valve 19 are installed at the top of the 0.4MPa sulfur-rich methanol flash tank 11. When the pressure in the 0.4MPa sulfur-rich methanol flash tank 11 exceeds the high alarm value and reaches the tripping pressure of the safety valve 21, the safety valve 21 will trip to release pressure. The manual valve 20 is fully open and sealed during normal system operation. When the 0.4MPa sulfur-rich methanol flash tank 11 requires maintenance, the bypass valve 19 is used for pressure relief and replacement.

[0049] Example 9 is a further improvement based on any one of Examples 1 to 8, and its details are as follows:

[0050] A wire mesh demister 12 is installed at the top of the 0.4 MPa sulfur-rich methanol flash tank 11 to prevent methanol entrainment in the flash vapor at the outlet of the 0.4 MPa sulfur-rich methanol flash tank 11.

[0051] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol, characterized in that, It includes the low-temperature methanol washing system body, as well as a 0.4MPa sulfur-rich methanol flash tank (11) and a second compressor (16); The liquid inlet of the 0.4MPa sulfur-rich methanol flash tank (11) is connected to the liquid outlet of the 0.8MPa carbon-rich methanol flash tank (2) of the low-temperature methanol washing system body. The gas outlet of the 0.4MPa sulfur-rich methanol flash tank (11) is connected to the inlet of the second compressor (16). The outlet of the second compressor (16) is connected to the crude gas inlet of the main washing tower (1) of the low-temperature methanol washing system body. The liquid outlet of the 0.4MPa sulfur-rich methanol flash tank (11) is connected to the liquid inlet of the 0.2MPa flash tower (6) of the low-temperature methanol washing system body.

2. The low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol according to claim 1, characterized in that, A third liquid level control valve (14) is installed on the pipeline between the liquid outlet end of the 0.4MPa sulfur-rich methanol flash tank (11) and the liquid inlet end of the 0.2MPa flash tower (6).

3. A low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol according to claim 2, characterized in that, The liquid outlet of the 0.4MPa sulfur-rich methanol flash tank (11) is connected to an emergency discharge pipeline, and an discharge control valve (15) is installed on the emergency discharge pipeline.

4. A low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol according to claim 3, characterized in that, The 0.4MPa sulfur-rich methanol flash tank (11) is equipped with a second level gauge (13) for detecting the internal liquid level. The second level gauge (13) is connected to the third level control valve (14) and the discharge control valve (15) respectively.

5. A low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol according to claim 1, characterized in that, A second level control valve (10) is installed on the pipeline between the liquid inlet end of the 0.4MPa sulfur-rich methanol flash tank (11) and the liquid outlet end of the 0.8MPa sulfur-rich methanol flash tank (3) of the low-temperature methanol washing system body. The second level control valve (10), the first level gauge (8) of the low-temperature methanol washing system body, and the first level control valve (9) of the low-temperature methanol washing system body are connected by a signal.

6. A low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol according to claim 5, characterized in that, The second compressor (16) is provided with a running detection signal transmitter (22) to detect its running status, and the running detection signal transmitter (22) is connected to the second liquid level control valve (10) by signal.

7. A low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol according to claim 1, characterized in that, The gas outlet end of the 0.4MPa sulfur-rich methanol flash tank (11) is connected to the regenerative oxidation device (7) of the low-temperature methanol washing system body through a pipeline. A pressure transmitter (17) and a pressure control valve (18) are sequentially installed on the pipeline at the gas outlet end of the 0.4MPa sulfur-rich methanol flash tank (11). The pressure transmitter (17) and the pressure control valve (18) are connected by a signal.

8. A low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol according to claim 7, characterized in that, A bypass valve (19) and a manual valve (20) are connected in parallel between the pressure transmitter (17) and the pressure control valve (18), and the other end of the bypass valve (19) and the manual valve (20) is connected to a safety valve (21).

9. A low-temperature methanol washing system for reusing effective gas in 0.8MPa sulfur-rich methanol according to claim 1, characterized in that, The top of the 0.4 MPa sulfur-rich methanol flash tank (11) is equipped with a wire mesh demister (12).

Images