System for purifying electronic-grade hydrogen sulfide from sulfur recovery tail gas

Abstract

The utility model relates to a sulfur recovery tail gas purification electronic grade hydrogen sulfide system which comprises an MDEA absorption tower, a regeneration tower, a temperature swing adsorption device, a light component removal tower and a heavy component removal tower which are sequentially connected along the material flow direction, and the light component removal tower and the heavy component removal tower are connected with ammonia circulation refrigeration devices. According to the system, tail gas is separated and purified by adopting an MDEA absorption preliminary separation + adsorption dehydration + rectification purification process, a high-purity electronic-grade hydrogen sulfide product is obtained, an alkali absorption tail gas treatment process is replaced, and the economic value of the tail gas is greatly improved. Cheap and easy-to-obtain ammonia is adopted as a refrigerant for compression decompression circulation to provide cooling capacity for the system, the temperature and the cooling capacity are utilized in a gradient mode, heat is provided by cheap and easy-to-obtain circulating water, and the cost of the purification system is low.

Description

Technical Field

[0001] The utility model relates to a system for purifying electronic-grade hydrogen sulfide from sulfur recovery tail gas, and relates to a chemical engineering equipment. Background Art

[0002] A large amount of tail gas rich in hydrogen sulfide is generated in the desulfurization and sulfur recovery section of the coal-to-hydrogen production process. At present, the common treatment process for the tail gas is to use the alkali absorption tail gas treatment process for treatment. The tail gas treatment consumes a large amount of alkali liquor, electricity and other costs, with a large consumption and low economic value.

[0003] Based on this, in order to solve the above technical problems, this case proposes a system for purifying electronic-grade hydrogen sulfide from sulfur recovery tail gas. Content of the Utility Model

[0004] In view of the deficiencies of the prior art, the technical problem to be solved by the utility model is to provide a system for purifying electronic-grade hydrogen sulfide from sulfur recovery tail gas.

[0005] In order to solve the above technical problems, the technical solution of the utility model is: a system for purifying electronic-grade hydrogen sulfide from sulfur recovery tail gas, including an MDEA absorption tower, a regeneration tower, a temperature swing adsorption device, a light component removal tower, and a heavy component removal tower that are sequentially connected along the material flow direction. An ammonia cycle refrigeration device is connected to the light component removal tower and the heavy component removal tower.

[0006] Preferably, a raw material tail gas pipeline is connected to the periphery of the MDEA absorption tower. The bottom of the MDEA absorption tower is connected to the regeneration tower through a first pipeline and a first heat exchanger and a first pump set arranged along the material flow direction on the first pipeline. A steam heating pipeline is connected to the regeneration tower, and the regeneration tower is connected to the MDEA absorption tower through a second pipeline and a second heat exchanger and a second pump set arranged along the material flow direction on the second pipeline. An amine liquid replenishment pipeline is also connected to the regeneration tower. The top of the MDEA absorption tower is connected to the tail gas treatment system.

[0007] Preferably, the top of the regeneration tower is connected to the inlet of the temperature swing adsorption device through a third pipeline and a third heat exchanger, a first gas-liquid separator, a first compressor, a fourth heat exchanger, and a second gas-liquid separator arranged along the material flow direction on the third pipeline.

[0008] Preferably, the gas outlet of the temperature swing adsorption device is connected to the inlet of the light component removal tower through a fifth heat exchanger. A sixth heat exchanger is connected to the top of the light component removal tower. The bottom of the light component removal tower is connected to the inlet of the heavy component removal tower.

[0009] Preferably, a seventh heat exchanger is connected to the top of the heavy component removal tower. The bottom of the heavy component removal tower is connected to the tail gas treatment system.

[0010] Preferably, the ammonia cycle refrigeration device includes a third gas-liquid separation tank. The outlet of the third gas-liquid separation tank is connected back to the inlet of the third gas-liquid separation tank through an ammonia cycle pipeline. Along the ammonia flow direction on the ammonia cycle pipeline between the outlet and the inlet of the third gas-liquid separation tank, a second compressor, an eighth heat exchanger, a first pressure reducing valve, a seventh heat exchanger connected to the top of the deweight tower, a second pressure reducing valve, a sixth heat exchanger connected to the top of the de-lighting tower, and a fifth heat exchanger connected between the temperature swing adsorption device and the de-lighting tower are sequentially arranged.

[0011] Compared with the prior art, the utility model has the following beneficial effects:

[0012] 1. The system realizes the separation and purification of tail gas by adopting the process of MDEA absorption for preliminary separation + adsorption dehydration + rectification purification to obtain high-purity electronic-grade hydrogen sulfide products, replacing the tail gas treatment process of alkali absorption, and greatly improving the economic value of the tail gas.

[0013] 2. Inexpensive and easily available ammonia is used as the refrigerant to compress and decompress the cycle to provide cold for the system. The temperature and cold are utilized in a stepped manner, and the heat is provided by inexpensive and easily available circulating water, so the cost of the purification system is relatively low.

[0014] The following further describes the present utility model in detail with reference to the drawings and specific embodiments. Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of an embodiment of the present utility model. Specific Embodiments

[0016] The following further describes the present utility model with reference to the drawings and embodiments.

[0017] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0018] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0019] Such as Figure 1As shown in the figure, this embodiment provides a system for purifying electronic-grade hydrogen sulfide from sulfur recovery tail gas, which includes an MDEA absorption tower 1, a regeneration tower 2, a temperature swing adsorption device 3, a light component removal tower 4, and a heavy component removal tower 5 connected in sequence along the material flow direction. An ammonia cycle refrigeration device 6 is connected to the light component removal tower and the heavy component removal tower.

[0020] High-purity electronic-grade hydrogen sulfide products can be separated and purified from the existing sulfur recovery tail gas.

[0021] In the embodiment of the present invention, a raw material tail gas pipeline 7 is connected to the periphery of the MDEA absorption tower. The bottom of the MDEA absorption tower is connected to the regeneration tower through a first pipeline and a first heat exchanger 8 and a first pump group 9 arranged in sequence along the material flow direction on the first pipeline. A steam heating pipeline 10 is connected to the regeneration tower. The regeneration tower is connected to the MDEA absorption tower through a second pipeline and a second heat exchanger 11 and a second pump group 12 arranged in sequence along the material flow direction on the second pipeline. An amine liquid replenishment pipeline 13 is also connected to the regeneration tower. The top of the MDEA absorption tower is connected to the tail gas treatment system.

[0022] In the embodiment of the present invention, the top of the regeneration tower is connected to the inlet of the temperature swing adsorption device through a third pipeline and a third heat exchanger 14, a first gas-liquid separation tank 15, a first compressor 16, a fourth heat exchanger 17, and a second gas-liquid separation tank 18 arranged in sequence along the material flow direction on the third pipeline.

[0023] In the embodiment of the present invention, the gas outlet of the temperature swing adsorption device is connected to the inlet of the periphery of the light component removal tower through a fifth heat exchanger 19. The top of the light component removal tower is connected to a sixth heat exchanger 20. The bottom of the light component removal tower is connected to the inlet of the periphery of the heavy component removal tower.

[0024] In the embodiment of the present invention, the top of the heavy component removal tower is connected to a seventh heat exchanger 21. The bottom of the heavy component removal tower is connected to the tail gas treatment system.

[0025] In the embodiment of the present invention, the ammonia cycle refrigeration device includes a third gas-liquid separation tank 22. The outlet of the third gas-liquid separation tank is connected back to the inlet of the third gas-liquid separation tank through an ammonia cycle pipeline 23. Along the ammonia flow direction on the ammonia cycle pipeline between the outlet and the inlet of the third gas-liquid separation tank, a second compressor 24, an eighth heat exchanger 25, a first pressure reducing valve 26, the seventh heat exchanger connected to the top of the heavy component removal tower, a second pressure reducing valve 27, the sixth heat exchanger connected to the top of the light component removal tower, and the fifth heat exchanger connected between the temperature swing adsorption device and the light component removal tower are arranged in sequence.

[0026] A purification process for a system for purifying electronic-grade hydrogen sulfide from sulfur recovery tail gas is carried out according to the following steps:

[0027] S1: The raw material tail gas (hydrogen sulfide content is about 33% - 40%, carbon dioxide content is about 60% - 65%, and there are also small amounts of impurities such as oxygen, nitrogen, carbon monoxide, hydrogen, methanol, and carbonyl sulfide), the flow rate is determined according to the actual required output. The pressure of the raw material tail gas is about 1.5 bar and it first enters the lower part of the MDEA absorption tower. The MDEA absorption process is a mature process. Based on the principle that the MDEA solution has a stronger absorption capacity for hydrogen sulfide than other components, in the absorption tower, the MDEA solution preferentially absorbs hydrogen sulfide gas and simultaneously absorbs a small amount of other impurity components. After absorption saturation, the MDEA solution is transferred to the regeneration tower through the first heat exchanger and the first pump group;

[0028] S2: In the regeneration tower, steam is used to heat the MDEA solution. After the temperature rises, the MDEA solution is regenerated and releases the absorbed gas. The regenerated solution has a higher temperature. First, it heats the adsorption-saturated solution coming from the absorption tower through the first heat exchanger, and then it is cooled to about 35°C - 40°C using circulating water in the second heat exchanger. Then it is pressurized by the second pump group and returned to the MDEA absorption tower for absorption. The gas not absorbed in the absorption tower is mainly carbon dioxide and impurity gases such as hydrogen sulfide, nitrogen, oxygen, and carbon monoxide. This part of the gas goes to the tail gas treatment system for treatment. The high-content gas hydrogen sulfide (hydrogen sulfide content is about 90% - 95%, carbon dioxide content is about 3% - 8%, and it also contains saturated moisture, trace amounts of nitrogen, carbon monoxide, etc.) taken out from the top of the regeneration tower has a relatively high temperature of about 80 - 90°C and is cooled to 35 - 40°C by circulating water in the third heat exchanger. Part of the moisture in the gas condenses into liquid and enters the first gas-liquid separation tank. The accumulated water at the bottom of the first gas-liquid separation tank is regularly discharged, and the gas at the top enters the first compressor and is compressed to 11 bar - 12 bar (setting this pressure can prevent carbon dioxide from approaching its triple point and turning into dry ice to block the heat exchanger in the subsequent process. At the same time, this pressure can make the temperature of the subsequent distillation cold source and heat source appropriate, making it a suitable method to use ammonia cycle to provide cold and circulating water to provide heat). After compression, it is cooled to 35°C - 40°C using circulating water in the fourth heat exchanger. Part of the moisture in the gas condenses into liquid and enters the second gas-liquid separation tank. The accumulated water at the bottom of the second gas-liquid separation tank is regularly discharged, and the gas at the top enters the temperature swing adsorption device (this is a commonly used device in the chemical industry, so it is briefly described);

[0029] S3: In the temperature swing adsorption device, based on the principle that the selective adsorption capacity of adsorbents such as molecular sieves for moisture is greater than that for hydrogen sulfide, the moisture in the gas is adsorbed, and the moisture content is reduced to 1 ppm - 2 ppm and then enters the subsequent distillation process. The moisture and hydrogen sulfide gas remaining in the adsorbent are discharged to the tail gas treatment system during the heating regeneration stage;

[0030] S4: The gas after moisture removal is cooled to about -20°C in the fifth heat exchanger and then enters the de-light tower (rectification pressure is about 11 bar) for the rectification process of gas-liquid mass transfer and heat transfer. The main function of the de-light tower is to remove low-boiling components such as carbon dioxide, oxygen, and nitrogen in hydrogen sulfide. The tail gas containing light-component impurities is at the top of the tower (carbon dioxide content is about 50% - 60%, hydrogen sulfide content is about 30% - 40%, and the rest are small amounts of nitrogen, oxygen, etc.). After the top gas of the tower is cooled by the sixth heat exchanger of the de-light tower, the gas phase amount is small and is directly sent to the tail gas treatment system for treatment, and the liquid phase is returned to the top of the tower as reflux; the bottom of the tower is the liquid after removing light components (hydrogen sulfide content reaches 99.5 - 99.9%), mainly containing trace amounts of impurities such as carbonyl sulfide and methanol, and continues to enter the de-heavy tower for the rectification process;

[0031] S5: The de-heavy tower (rectification pressure is about 10.5 - 11 bar) mainly uses the rectification principle to remove impurity components such as carbonyl sulfide and methanol with boiling points relatively higher than that of hydrogen sulfide in the gas. A part of the liquid rich in heavy-component impurities such as carbonyl sulfide and methanol is drawn from the bottom of the de-heavy tower and sent to the tail gas treatment system. The qualified electronic-grade hydrogen sulfide product (hydrogen sulfide purity ≥ 99.9995%) is produced by liquid-phase extraction at the outlet of the seventh heat exchanger at the top of the de-heavy tower.

[0032] Electronic-grade hydrogen sulfide is widely used in fields such as semiconductor PV, LED, LCD, and IC.

[0033] In the embodiment of the present utility model, during the process of steps S4 - S5, during the rectification operation process, heat needs to be continuously provided to the reboiler at the bottom of the tower to partially vaporize the liquid at the bottom of the tower as the rising gas necessary for the rectification process, and cold energy needs to be provided to the condenser heat exchanger at the top of the tower to liquefy part of the gas as the reflux liquid necessary for the rectification process.

[0034] In the embodiment of the present utility model, in this process, the temperature of the reboiler of the de-light tower is about 0 - 5°C, and the temperature of the reboiler of the de-heavy tower is about 22 - 25°C. Therefore, the most commonly used industrial circulating water (about 30 - 35°C) is selected as the heat source for the reboilers of the two towers.

[0035] In the embodiment of the present utility model, during the process of steps S4 - S5, the condensation working temperature of the de-light tower is about -19°C to -22°C, and the condensation temperature of the de-heavy tower is about 0°C to 3°C. An ammonia cycle refrigeration device is used to provide cold energy for the top condensation of the de-light tower, the top condensation of the de-heavy tower, and the cooling of the raw materials before entering the de-light tower.

[0036] In the embodiment of the present utility model, ammonia is first compressed to about 21 bar by a second compressor, cooled to 35°C - 40°C by circulating water and completely liquefied, then decompressed to about 2 bar by a first pressure reducing valve. After decompression, part of the liquid ammonia vaporizes and the temperature drops to about -9°C. Then it enters the seventh heat exchanger of the heavy component removal column as a cold source, and the ammonia is further vaporized with the temperature remaining basically unchanged at about -9°C. After that, the ammonia is further decompressed to about 1.3 bar by a second pressure reducing valve and the temperature drops to about -28°C. Then the ammonia continues to enter the sixth heat exchanger and the fifth heat exchanger of the light component removal column respectively to cool the feed gas, and the ammonia is completely vaporized and the temperature rises to 20°C - 25°C. After that, the ammonia enters the second compressor again to achieve circulation.

[0037] To prevent improper adjustment of the cooling capacity in the actual process, resulting in incomplete vaporization of some ammonia before entering the second compressor, a third gas-liquid separation tank is designed to prevent liquid from entering the second compressor and causing damage to it. At the same time, the third gas-liquid separation tank can also be used as a buffer tank for adding liquid ammonia. In addition, as an alternative solution, gas-liquid separation buffer tanks can also be provided after the first pressure reducing valve and the second pressure reducing valve to facilitate the adjustment of the cooling capacity. When the cooling capacity of the system is excessive, part of the liquid can be temporarily stored in the buffer tank, and at the same time, the compressor frequency is reduced to reduce the flow rate of the circulating ammonia.

[0038] The above are only the preferred embodiments of the present utility model, and do not limit the present utility model in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the technical solution content of the present utility model still belong to the protection scope of the technical solution of the present utility model.

Claims

1. A sulfur recovery tail gas purification electronic grade hydrogen sulfide system, characterized by: The invention comprises an MDEA absorption tower, a regeneration tower, a temperature-swing adsorption device, a light-removal tower and a heavy-removal tower which are sequentially connected along the material flow direction, wherein the light-removal tower and the heavy-removal tower are connected with an ammonia circulation refrigeration device.

2. The sulfur recovery tail gas purification electronic grade hydrogen sulfide system according to claim 1, characterized in that: The MDEA absorption tower is connected to a raw material tail gas pipeline at its periphery, and the bottom of the MDEA absorption tower is connected to a regeneration tower via a first pipeline and a first heat exchanger and a first pump group sequentially arranged on the first pipeline along the material flow direction, and a steam heating pipeline is connected to the regeneration tower, and the regeneration tower is connected to the MDEA absorption tower via a second pipeline and a second heat exchanger and a second pump group sequentially arranged on the second pipeline along the material flow direction, and an amine liquid replenishment pipeline is also connected to the regeneration tower, and the top of the MDEA absorption tower is connected to a tail gas treatment system.

3. The sulfur recovery tail gas purification electronic grade hydrogen sulfide system according to claim 1 is characterized by: The top of the regeneration tower is connected to the inlet of the temperature swing adsorption device through the third pipeline and the third heat exchanger, the first gas-liquid separation tank, the first compressor, the fourth heat exchanger, and the second gas-liquid separation tank arranged in sequence along the material flow on the third pipeline.

4. The sulfur recovery tail gas purification electronic grade hydrogen sulfide system according to claim 1, characterized in that: The gas outlet of the temperature-swing adsorption device is connected to the peripheral inlet of the light-removal tower via the fifth heat exchanger, the top of the light-removal tower is connected to the sixth heat exchanger, and the bottom of the light-removal tower is connected to the peripheral inlet of the heavy-removal tower.

5. The sulfur recovery tail gas purification electronic grade hydrogen sulfide system according to claim 1, characterized in that: The top of the deweighting tower is connected to a seventh heat exchanger, and the bottom of the deweighting tower is connected to an exhaust gas treatment system.

6. The sulfur recovery tail gas purification electronic grade hydrogen sulfide system according to claim 1, characterized in that: The ammonia cycle refrigeration device includes a third gas-liquid separation tank, the outlet of the third gas-liquid separation tank is connected back to the inlet of the third gas-liquid separation tank through an ammonia circulation pipeline, and the ammonia circulation pipeline between the outlet and the inlet of the third gas-liquid separation tank is sequentially provided with a second compressor, an eighth heat exchanger, a first pressure reducing valve, a seventh heat exchanger connected to the top of a de-heavy tower, a second pressure reducing valve, a sixth heat exchanger connected to the top of a light-removal tower, and a fifth heat exchanger connected between the temperature variable adsorption device and the light-removal tower along the ammonia flow direction.

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