Carbon dioxide recovery unit for removing sulfides

Abstract

This invention discloses a carbon dioxide recovery device for removing sulfides, comprising an air compressor (13), a carbon dioxide compressor (15), a desulfurizer (17), and an air pipe (19). The device is characterized in that the air compressor (13) and the desulfurizer (17) are connected via the air pipe (19), an air buffer tank (14) is provided on the air pipe (19), and a water cooler (16) is provided on the pipe connecting the carbon dioxide compressor (15) and the desulfurizer (17). This invention can improve the quality of liquid carbon dioxide products, meeting national industrial standards, and ensuring stable quality.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a carbon dioxide recovery device for removing sulfides. Background Technology

[0002] In the coal gasification process for ammonia synthesis, a conversion step transforms CO in the crude coal gas into CO2 and H2. During gas purification, the CO2 is absorbed by a low-temperature methanol washing unit and emitted as tail gas (with a CO2 content of approximately 98%). To achieve energy conservation and emission reduction, the CO2 in the tail gas from the low-temperature methanol washing unit can be used to produce liquid carbon dioxide through a carbon dioxide recovery unit. However, the tail gas from the low-temperature methanol washing unit, used as feed gas for the carbon dioxide recovery unit, contains small amounts of N2 and sulfides, which can cause an off-odor in the produced liquid carbon dioxide, affecting its quality stability. Analysis confirmed that this is due to the presence of sulfides. To remove the sulfides, desulfurizing agents from several companies have been used to desulfurize the carbon dioxide recovery unit, but the results have been unsatisfactory. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a carbon dioxide recovery device for removing sulfides that can improve the quality of liquid carbon dioxide products, meet national industrial standards, and has stable quality.

[0004] The carbon dioxide recovery device for removing sulfides of the present invention includes an air compressor, a carbon dioxide compressor, a desulfurizer, and an air pipe, wherein: the air compressor and the desulfurizer are connected through an air pipe, an air buffer tank is provided on the air pipe, and a water cooler is provided on the pipe connecting the carbon dioxide compressor and the desulfurizer.

[0005] The aforementioned carbon dioxide recovery device for removing sulfides includes: an air compressor outlet boundary valve, an emergency shut-off valve, an air buffer tank inlet valve, and an air buffer tank inlet check valve sequentially installed on the air pipe connecting the air compressor outlet boundary valve and the emergency shut-off valve; a branch pipe is installed on the air pipe connecting the air compressor outlet boundary valve and the emergency shut-off valve, and a drain valve is installed on the branch pipe; a branch pipe is installed on the air pipe connecting the emergency shut-off valve and the air buffer tank inlet valve, and an emergency pressure relief regulating valve is installed on the branch pipe.

[0006] The aforementioned carbon dioxide recovery device for removing sulfides includes: an emergency shut-off valve for the air buffer tank outlet, a check valve for the flow meter inlet, a flow meter inlet valve, a rotor flow meter, and an air boundary valve, sequentially installed on the air pipe connecting the air buffer tank outlet emergency shut-off valve and the flow meter inlet check valve; a branch pipe is installed on the air pipe connecting the air buffer tank outlet emergency shut-off valve and the flow meter inlet check valve, and an emergency pressure relief regulating valve is installed on the branch pipe.

[0007] The aforementioned carbon dioxide recovery device for removing sulfides includes a regulating valve installed before the inlet of the desulfurizer.

[0008] The aforementioned carbon dioxide recovery device for removing sulfides includes a water cooler equipped with a circulating water supply and a circulating water return system.

[0009] Compared with existing technologies, this invention has significant advantages. As can be seen from the above technical solution: this invention installs an air pipe from the air compressor outlet of the air separation unit to the carbon dioxide desulfurizer, along with a buffer tank to stabilize pressure, a rotor flow meter to accurately regulate flow, and corresponding control valves for overall regulation. In the desulfurizer, COS (carbon oxides) in the feed gas and moisture in the air undergo a chemical reaction to generate H2S and CO2. The adsorbent then removes the H2S, resulting in better desulfurization of the carbon dioxide unit and ensuring that the carbon dioxide product meets industrial-grade standards. Simultaneously, a safety interlock is implemented to prevent feed gas from the carbon dioxide recovery unit from leaking into the air separation unit, ensuring that the newly added air pipe will not affect the normal operation of the air separation unit. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of the present invention.

[0011] The following are labels in the diagram: 1. Flow meter inlet valve, 2. Flow meter inlet check valve, 3. Air buffer tank outlet emergency shut-off valve, 4. Emergency pressure relief regulating valve A, 5. Air buffer tank inlet check valve, 6. Air buffer tank inlet valve, 7. Emergency pressure relief regulating valve B, 8. Emergency shut-off valve, 9. Drain valve, 10. Air compressor outlet boundary valve, 11. Rotor flow meter, 12. Air boundary valve, 13. Air compressor, 14. Air buffer tank, 15. Carbon dioxide compressor, 16. Water cooler, 17. Desulfurizer, 18. Regulating valve, 19. Air pipe. Detailed Implementation

[0012] like Figure 1 As shown, the carbon dioxide recovery device for removing sulfides of the present invention includes an air compressor 13, a carbon dioxide compressor 15, a desulfurizer 17, and an air pipe 19, wherein: the air compressor 13 and the desulfurizer 17 are connected through the air pipe 19, an air buffer tank 14 is provided on the air pipe 19, and a water cooler 16 is provided on the pipe connecting the carbon dioxide compressor 15 and the desulfurizer 17, and the water cooler 16 is provided with circulating water supply and circulating water return.

[0013] On the air pipe 19 connecting the outlet of air compressor 13 and the inlet of air buffer tank 14, the following are sequentially installed: air compressor outlet boundary valve 10, emergency shut-off valve 8, air buffer tank inlet valve 6, and air buffer tank inlet check valve 5. A branch pipe is installed on the air pipe 19 connecting the air compressor outlet boundary valve 10 and the emergency shut-off valve 8, and a drain valve 9 is installed on the branch pipe. A branch pipe is also installed on the air pipe 19 connecting the emergency shut-off valve 8 and the air buffer tank inlet valve 6, and an emergency pressure relief regulating valve B7 is installed on the branch pipe.

[0014] On the air buffer tank 14 outlet and the connected air pipe 19, there are sequentially installed an air buffer tank outlet emergency shut-off valve 3, a flow meter inlet check valve 2, a flow meter inlet valve 1, a rotor flow meter 11, and an air boundary valve 12. A branch pipe is provided on the air pipe 19 connecting the air buffer tank outlet emergency shut-off valve 3 and the flow meter inlet check valve 2, and an emergency pressure relief regulating valve A4 is provided on the branch pipe.

[0015] A regulating valve 18 is installed before the inlet of the desulfurizer 17.

[0016] Working principle:

[0017] 1. The feed gas from the low-temperature methanol washing unit is pressurized to 5.5 MPa by the carbon dioxide compressor 15, cooled to 30°C by the water cooler 16, and then enters the desulfurizer 17;

[0018] 2. Before introducing air, to prevent overpressure in the pipeline, first check that the air compressor outlet boundary valve 10, drain valve 9, emergency pressure relief regulating valve B7, emergency pressure relief regulating valve A4, flow meter inlet valve 1, and air boundary valve 12 are in the closed state;

[0019] 3. Next, slowly open the emergency shut-off valve 8, the air buffer tank inlet valve 6, and the air buffer tank outlet emergency shut-off valve 3; then open the air compressor outlet boundary valve 10, and slowly open the air boundary valve 12 and the flow meter inlet valve 1 to introduce air. Control the air flow rate at 2-3 Nm using the rotor flow meter 11. 3 / h;

[0020] 4. After the air passes through the outlet of the air compressor 13, it passes through the boundary valve 10, emergency shut-off valve 8, air buffer tank inlet valve 6, air buffer tank inlet check valve 5, air buffer tank 14, air buffer tank outlet emergency shut-off valve 3, flow meter inlet check valve 2, flow meter inlet valve 1, rotor flow meter 11, and air boundary valve 12. After mixing with the raw material gas, it enters the desulfurizer 17 through the regulating valve 18. In the desulfurizer, COS in the raw material gas and moisture in the air undergo a chemical reaction to generate H2S and CO2. Then, the adsorbent removes the H2S, achieving the purpose of removing sulfides.

[0021] 5. Ensure the pressure after the flow meter inlet valve 1 does not exceed 6 MPa. ① When the pressure is greater than or equal to 6 MPa, immediately close the emergency shut-off valve 3 at the air buffer tank outlet and open the emergency pressure relief regulating valve A4 to release pressure. ② When the pressure difference of the emergency shut-off valve 3 at the air buffer tank outlet is less than 1 MPa, the valve will automatically close and release pressure through the interlocked fully open emergency pressure relief regulating valve A4.

[0022] 6. Take precautions to prevent carbon dioxide from backflowing into the air separation unit. When air compressor 15 trips or the pressure after air compressor outlet boundary valve 10 drops below 3.5 MPa, emergency shut-off valve 8 will automatically close and interlock to open emergency pressure relief regulating valve B7 for automatic pressure relief.

[0023] The device of this invention can effectively remove sulfides such as COS from the raw gas from the low-temperature methanol washing unit, achieving the quality of industrial-grade liquid carbon dioxide products. The device operates safely and stably during production, with low investment costs and high economic benefits.

[0024] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments without departing from the technical essence of the present invention shall still fall within the scope of the present invention.

Claims

1. A carbon dioxide recovery device for removing sulfides, comprising an air compressor (13), a carbon dioxide compressor (15), a desulfurizer (17), and an air pipe (19), characterized in that: The air compressor (13) is connected to the desulfurizer (17) via an air pipe (19). An air buffer tank (14) is installed on the air pipe (19). An air buffer tank outlet emergency shut-off valve (3), a flow meter inlet check valve (2), a flow meter inlet valve (1), a rotor flow meter (11), and an air boundary valve (12) are sequentially installed on the outlet of the air buffer tank (14) and the connected air pipe (19). A water cooler (16) is installed on the pipe connecting the carbon dioxide compressor (15) and the desulfurizer (17). The water cooler (16) is equipped with circulating water supply and circulating water return. A regulating valve (18) is installed before the inlet of the desulfurizer (17). The device is also equipped with a safety interlock. a) When the outlet pressure of the air buffer tank is ≥6MPa, immediately close the emergency shut-off valve (3) at the outlet of the air buffer tank and open the emergency pressure relief regulating valve A (4). b) When the air compressor (13) trips or the pressure after the air compressor outlet boundary valve (10) is <3.5MPa, the emergency shut-off valve (8) is automatically closed and the emergency pressure relief regulating valve B (7) is opened.

2. The carbon dioxide recovery device for removing sulfides as described in claim 1, characterized in that: On the air pipe (19) connecting the outlet of the air compressor (13) and the inlet of the air buffer tank (14), there are sequentially installed an air compressor outlet boundary valve (10), an emergency shut-off valve (8), an air buffer tank inlet valve (6), and an air buffer tank inlet check valve (5).

3. The carbon dioxide recovery device for removing sulfides as described in claim 2, characterized in that: A branch pipe is provided on the air pipe (19) connecting the air compressor outlet boundary valve (10) and the emergency shut-off valve (8), and a drain valve (9) is provided on the branch pipe; a branch pipe is provided on the air pipe (19) connecting the emergency shut-off valve (8) and the air buffer tank inlet valve (6), and an emergency pressure relief regulating valve B (7) is provided on the branch pipe.

4. The carbon dioxide recovery device for removing sulfides as described in claim 1, characterized in that: An emergency shut-off valve (3) at the outlet of the air buffer tank and a check valve (2) at the inlet of the flow meter are connected by a branch pipe (19), and an emergency pressure relief regulating valve A (4) is provided on the branch pipe.

Images