Natural gas desulfurization and decarbonization equipment

Abstract

The utility model provides natural gas desulfurization and decarbonization equipment which comprises a natural gas filter and an absorption tower, a top outlet of the absorption tower is connected with a deacidified gas separator, a top inlet of the absorption tower is connected with a lean amine liquid cooler, and a bottom outlet of the absorption tower is connected with a flash tank; a first-stage filter, a second-stage filter and a third-stage filter are sequentially arranged between the flash tank and the lean-rich amine liquid heat exchanger, the lean-rich amine liquid cooler is connected with an amine circulating pump, the amine circulating pump is further connected with a first outlet in the top of the lean-rich amine liquid heat exchanger and an amine liquid storage tank, and the lean-rich amine liquid heat exchanger is connected with a regeneration tower. An outlet in the top of the regeneration tower is sequentially connected with an acid gas air cooler, an acid gas cooler, a regeneration tower return tank, an acidic water return pump and a second inlet in the top of the regeneration tower; and the regeneration tower is also connected with a regeneration tower reboiler. The multi-stage filter and the absorption liquid cyclic regeneration device are arranged, so that amine liquid is filtered and purified in a multi-layer and three-dimensional manner, and cyclic utilization of the absorption liquid is realized to the greatest extent.

Description

Technical Field

[0001] The utility model relates to the technical field of natural gas purification, in particular to a natural gas desulfurization and decarbonization device. Background Art

[0002] The process flow of natural gas amine desulfurization and decarbonization is designed based on the reaction between alcohol amines and acid gas. The existing amine desulfurization and decarbonization equipment cannot recycle the intermediate products, resulting in huge waste; at the same time, the intermediate products are not filtered, which will cause pollution.

[0003] A Chinese invention patent, publication number CN118222338A, entitled "A Natural Gas Desulfurization and Decarbonization Apparatus, Method, and Application," discloses a natural gas desulfurization and decarbonization apparatus, method, and application, comprising a desulfurization and decarbonization apparatus and a desulfurization unit. The desulfurization and decarbonization unit comprises a first heat exchanger, a desulfurization tower, a purifier separator, a pressure control device, a regeneration tower, a lean-rich liquid heat exchanger, a first air cooler, a rich liquid flash tank, an acid gas splitter, and a second air cooler. This technical solution can meet the desulfurization and decarbonization requirements of feed gases with varying processing volumes, H2S and CO2 contents, and different natural gas products. However, this technical solution does not recycle intermediate products and does not include filtration. Utility Model Content

[0004] To address the problem of prior art equipment failing to process intermediate products from the amine desulfurization and decarbonization of natural gas, resulting in waste and pollution, this utility model proposes a natural gas desulfurization and decarbonization device. After filtration, the natural gas is mixed with an absorption liquid in an absorption tower to remove acidic components. The deacidified gas, after droplets are removed, is then sent to a post-processing system. The rich amine liquid undergoes flash evaporation, filtration, and heat exchange before being regenerated in a regeneration tower, and the lean amine liquid is recycled. The acid gas, after cooling and liquid reflux, is then sent to a post-processing system. This device maximizes the recycling of the amine liquid, ensuring effective natural gas desulfurization and desulfurization.

[0005] The utility model is realized by the following technical solutions: comprising a natural gas filter, wherein the outlet of the natural gas filter is connected to the bottom inlet of an absorption tower, the top outlet of the absorption tower is connected to a deacidified gas separator, the top inlet is connected to a lean amine liquid cooler, and the bottom outlet is connected to a flash tank, a primary filter, a secondary filter, and a tertiary filter are sequentially arranged between the bottom outlet of the flash tank and the first bottom inlet of a lean and rich amine liquid heat exchanger, a gas outlet is further provided at the top of the flash tank, the top inlet of the lean amine liquid cooler is connected to an amine circulation pump, the amine circulation pump is further connected to the first top outlet of the lean and rich amine liquid heat exchanger and an amine liquid storage tank, the second top outlet of the lean and rich amine liquid heat exchanger is connected to the first top inlet of a regeneration tower, and the second bottom inlet is connected to the bottom outlet of the regeneration tower, the top outlet of the regeneration tower is sequentially connected to an acid gas air cooler, the top inlet of the acid gas cooler, the bottom outlet of the acid gas cooler, the top inlet of a regeneration tower reflux tank, the bottom outlet of the regeneration tower reflux tank, an acidic water reflux pump, and the second top inlet of the regeneration tower; and the regeneration tower is further connected to a reboiler for the regeneration tower.

[0006] Furthermore, the flash tank is a horizontal tank, and a nitrogen inlet is provided on the top of the flash tank and is connected to a nitrogen filling device.

[0007] Furthermore, the absorption tower and the regeneration tower are plate towers.

[0008] Furthermore, the number of plates in the absorption tower is 14 to 20, and the number of plates in the regeneration tower is 20 to 24.

[0009] Furthermore, the spacing between the plates of the absorption tower and the regeneration tower is 0.6 m, a mist catcher is provided on the top of the tower, and the distance between the top plate and the mist catcher is 0.9 to 1.2 m.

[0010] Furthermore, the natural gas filter is a fiber filter, the lean amine liquid cooler is a shell and tube heat exchanger, and the lean and rich amine liquid heat exchanger is a plate heat exchanger.

[0011] Furthermore, the first-stage filter is a cartridge filter; the second-stage filter is an activated carbon filter; and the third-stage filter is a cartridge filter.

[0012] Furthermore, the acid gas cooler is a shell and tube heat exchanger.

[0013] Furthermore, the operating temperature of the natural gas filter is 40°C and the operating pressure is 7.0-7.5 MPa; the operating temperature of the absorption tower is 50°C and the operating pressure is 7.0-7.5 MPa; the operating temperature of the flash tank is 50°C and the operating pressure is 0.5 MPa.

[0014] Furthermore, the operating temperature of the primary filter, the secondary filter and the tertiary filter is 50° C., and the operating pressure is 0.5 MPa.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. A multi-stage filter is set up to filter and purify the amine liquid in a multi-level three-dimensional manner, so as to maximize the recycling of the amine liquid.

[0017] 2. Set up an amine liquid replenishment system to replenish amine liquid loss in time to ensure good desulfurization and decarbonization effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the overall structure of the desulfurization and decarbonization equipment in this utility model.

[0019] Indicated in the figure:

[0020] 1. Natural gas filter; 2. Absorption tower; 3. Lean amine liquid cooler; 4. Deacidification gas separator; 5. Flash tank; 6. Primary filter; 7. Secondary filter; 8. Tertiary filter; 9. Lean and rich amine liquid heat exchanger; 10. Regeneration tower; 11. Amine circulation pump; 12. Regeneration tower reboiler; 13. Acid gas air cooler; 14. Acid gas cooler; 15. Regeneration tower reflux tank; 16. Acid water reflux pump. DETAILED DESCRIPTION

[0021] Advantages and features of the present invention will be illustrated and explained through the following non-limiting description of preferred embodiments, which are given as examples only with reference to the accompanying drawings.

[0022] like Figure 1As shown, the present invention provides a natural gas desulfurization and decarbonization device, comprising a natural gas filter 1. Natural gas in the natural gas filter 1 is supplied from a compressor, and accumulated liquid flows out of the bottom outlet of the natural gas filter 1. The outlet of the natural gas filter 1 is connected to the bottom inlet of an absorption tower 2, the top outlet of the absorption tower 2 is connected to a deacidified gas separator 4, the top inlet of the absorption tower 2 is connected to a lean amine liquid cooler 3, and the bottom outlet of the absorption tower 2 is connected to a flash tank 5. A primary filter 6, a secondary filter 7, and a tertiary filter 8 are sequentially disposed between the bottom outlet of the flash tank 5 and the first bottom inlet of a lean-rich amine liquid heat exchanger 9 to filter out solid impurities that may be carried into the absorption liquid during the absorption process. The top of the flash tank 5 also has a nitrogen inlet and a gas outlet. Nitrogen is supplied to the nitrogen inlet from a nitrogen filling device, and flash gas flashed in the flash tank 5 is passed through the gas outlet to a flare system. The top inlet of the lean amine liquid cooler 3 is connected to an amine circulation pump 11, which is further connected to the first top outlet of the lean-rich amine liquid heat exchanger 9 and the amine liquid storage tank. The second top outlet of the lean-rich amine liquid heat exchanger 9 is connected to the first top inlet of the regeneration tower 10, and the second bottom inlet is connected to the bottom outlet of the regeneration tower 10. The top outlet of the regeneration tower 10 is connected to the acid gas air cooler 13, which is connected to the top inlet of the acid gas cooler 14. The second top inlet of the regeneration tower 10 is connected to the acid water reflux pump 16. The bottom outlet of the acid gas cooler 14 is connected to the top inlet of the regeneration tower reflux tank 15, and the bottom outlet of the regeneration tower reflux tank 15 is connected to the acid water reflux pump 16. The regeneration tower 10 is also connected to the regeneration tower reboiler 12. The acid gas cooler 14 has a circulating water inlet at the bottom and a circulating water outlet at the top. The regeneration tower reflux tank 15 has a gas outlet at the top.

[0023] After passing through natural gas filter 1 to remove free liquid and entrained solid impurities, the natural gas feed enters the bottom of absorption tower 2. It then countercurrently contacts the absorbent liquid, i.e., amine solution, flowing downward from the top of absorption tower 2, removing acidic components. The deacidified gas leaving the top of absorption tower 2 contains saturated water and must pass through deacidified gas separator 4 to remove entrained solution droplets before exiting the device and heading to subsequent processing systems.

[0024] The natural gas amine desulfurization and decarbonization process consists of four steps: absorption, flash evaporation, heat exchange, and regeneration. The absorption step removes the acidic components from the natural gas feed gas to the specified level or requirement. The flash evaporation step removes the hydrocarbons absorbed during the absorption of the acidic components from the rich amine solution. The heat exchange step recovers the heat of the hot lean amine solution leaving the regeneration tower. The regeneration step desorbs the acidic components absorbed from the rich amine solution, converting it into lean amine solution for recycling.

[0025] The rich amine liquid flowing from the bottom of absorption tower 2 is depressurized and enters flash tank 5, where hydrocarbons absorbed by the absorbent are removed. The rich amine liquid then passes through primary filter 6, secondary filter 7, and tertiary filter 8, respectively, to remove solid impurities that may have been carried into the rich amine liquid during the absorption process. The filtered rich amine liquid enters lean-rich amine heat exchanger 9, where it is heated by the hot lean amine liquid before entering the upper portion of regeneration tower 10, which operates at low pressure. Upon entering regeneration tower 10, a portion of the acidic components in the rich amine liquid flash off on the top tray of regeneration tower 10. As the rich amine, dissolved in the trays or packing within regeneration tower 10, flows downward to the bottom of regeneration tower 10, the acidic components in the rich amine liquid are further stripped out by heated and vaporized gases, primarily water vapor, in reboiler 12. As a result, the solution exiting regeneration tower 10 is lean amine liquid, containing only a small amount of residual acidic gases that have not been stripped out. The hot lean amine liquid flows out from the bottom of the regeneration tower 10 and enters the lean-rich amine liquid heat exchanger 9 from the bottom to exchange heat with the filtered rich amine liquid. The temperature drops to more than 5°C higher than the dew point of the hydrocarbon gas in the absorption tower 2. After being pressurized by the amine circulation pump 11, it enters the absorption tower 2 for the next round of absorption and is recycled.

[0026] The acidic components and water vapor stripped from the rich amine solution leave the top of the regeneration tower 10, are cooled in the acid gas air cooler 13 and acid gas cooler 14, and then flow to the regeneration tower reflux tank 15. Condensed water flows out of the bottom of the regeneration tower reflux tank 15 as reflux and returns to the top of the regeneration tower 10. Depending on its composition and flow rate, the acid gas discharged from the top of the regeneration tower reflux tank 15 may be sent to the sulfur recovery unit, compressed and then reinjected into the formation to enhance oil recovery, or treated and then flared.

[0027] Amine loss is inevitable during the above process. To ensure absorption, it must be replenished. A bypass is typically provided at the inlet of the amine circulation pump 11 for replenishment. Solvent loss primarily results from evaporation, carryover, degradation, and mechanical losses, and generally does not exceed 30 kg / 106 m3.

[0028] As mentioned above, the absorption tower 2 and the regeneration tower 10 can be packed towers or plate towers, and the plate towers usually use valve trays.

[0029] The number of plates in absorption tower 2 should be calculated based on the H2S and CO2 content in the natural gas feed and the quality indicators of the purified gas. Typically, absorption tower 2 has 14 to 20 plates, while regeneration tower 10 has 20 to 24 plates below the rich amine inlet. To reduce solution carryover losses, 3 to 5 plates are installed above the rich amine feed. Proper control of the solution residence time within the tower (limiting the number of plates or solution circulation) can improve selectivity. The tray spacing between absorption tower 2 and regeneration tower 10 is generally 0.6 m. A mist catcher is installed at the top of the tower, with the distance between the top tray and the mist catcher being 0.9 to 1.2 m.

[0030] The function of the regeneration tower 10 is to use the water vapor and heat provided by the regeneration tower reboiler 12 to decompose the compounds generated by the absorption liquid and the acidic components in a countercurrent direction, thereby desorbing the acidic components. The water vapor also has a stripping effect on the solution, that is, it reduces the partial pressure of the acidic components in the gas phase, allowing more acidic components to be desorbed from the solution. The amount of steam depends on the required quality of the lean amine liquid, the type of absorption liquid and the number of tower plates. The ratio of the amount of water vapor to the amount of acidic gas substances in the exhaust gas from the top of the regeneration tower 10 is called the reflux ratio of the tower. The water vapor is condensed by the acid gas air cooler 13 and the acid gas cooler 14 and then sent back to the top of the regeneration tower 10 as reflux. The acid gas containing saturated water vapor is removed from the sulfur recovery device, or is reinjected or discharged after treatment and incineration.

[0031] Dissolved hydrocarbons in the rich amine solution can easily cause foaming. Excessive hydrocarbons in the acid gas can also affect the sulfur quality of the Claus sulfur recovery unit. To desorb as much dissolved hydrocarbons as possible from the rich amine solution before it enters the regeneration tower 10, a flash tank 5 is installed. Flash tank 5 is typically a horizontal tank, and the hydrocarbons flashed out are used as fuel. The lower the flash pressure and the higher the temperature, the better the flash evaporation effect. For two-phase separation (lean feed gas, low absorption pressure, and rich liquid containing only methane and ethane), the solution resides in flash tank 5 for 10 to 15 minutes. For three-phase separation (rich feed gas, high absorption pressure, and rich liquid containing heavier hydrocarbons), the solution resides in flash tank 5 for 20 to 30 minutes. To enhance the flash evaporation effect, flash tank 5 is typically equipped with a nitrogen filling device.

[0032] The natural gas filter 1 usually adopts a fiber filter, which can filter both solid impurities and condensed liquid droplets.

[0033] The lean amine liquid cooler 3 generally uses a shell and tube heat exchanger, using circulating water as the cooling medium, with the circulating water flowing through the shell side and the amine liquid flowing through the tube side.

[0034] The first-stage filter 6 generally uses a cartridge filter for preliminary filtration; the second-stage filter 7 generally uses activated carbon filtration or sand filtration for fine filtration; the third-stage filter 8 generally uses a cartridge filter for safety filtration.

[0035] The lean and rich amine liquid heat exchanger 9 generally uses a plate heat exchanger.

[0036] The heat transfer medium of the regeneration tower reboiler 12 is generally steam or heat transfer oil, and the actual reboiler steam temperature is selected according to the amine solution formula.

[0037] The acid gas cooler 14 generally uses a shell and tube heat exchanger, using circulating water as the cooling medium, with the circulating water flowing through the shell side and the acid gas flowing through the tube side.

[0038] The operating conditions for the relevant equipment in this process flow are as follows (adjustments may be made based on the actual properties of the natural gas feed and the amine liquid): Natural gas filter 1: Operating temperature 40°C, operating pressure 7.0-7.5 MPa, solid and liquid filtration accuracy 1 μm, solid and liquid filtration efficiency >99%. Absorber 2: Operating temperature 50°C, operating pressure 7.0-7.5 MPa. Lean amine cooler 3: Operating temperature 40-75°C, operating pressure 7.5 MPa. Deacidification gas separator 4: Operating temperature 50°C, operating pressure 7.0-7.5 MPa. Flash tank 5: Operating temperature 50°C, operating pressure 0.5 MPa. Primary filter 6, secondary filter 7, and tertiary filter 8: Operating temperature 50°C, operating pressure 0.5 MPa. Lean-rich amine heat exchanger 9: Operating temperature 40-100°C, operating pressure 0.5 MPa on the cold side, and 70-125°C, operating pressure 0.2 MPa on the hot side. Regeneration tower 10 operates at a temperature of 50-130°C and a pressure of -0.1-0.2 MPa. Regeneration tower reboiler 12 operates at a temperature of 70-125°C and a pressure of 0.2 MPa. Acid gas air cooler 13 operates at a temperature of 65-130°C and a pressure of -0.1-0.2 MPa. Acid gas cooler 14 operates at a temperature of 50-65°C and a pressure of -0.1-0.2 MPa. Regeneration tower reflux tank 15 operates at a temperature of 50°C and a pressure of -0.1-0.2 MPa. Acid water reflux pump 16 has a head of 50 m. Amine circulation pump 11 has a head of 850 m.

[0039] In addition to the above embodiments, the present invention may also have other implementation methods. Any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A natural gas desulfurization and decarbonization device, comprising a natural gas filter (1), characterized in that: The outlet of the natural gas filter (1) is connected to the bottom inlet of the absorption tower (2), the top outlet of the absorption tower (2) is connected to the deacidified gas separator (4), the top inlet is connected to the lean amine liquid cooler (3), and the bottom outlet is connected to the flash tank (5). A primary filter (6), a secondary filter (7) and a tertiary filter (8) are sequentially arranged between the bottom outlet of the flash tank (5) and the first bottom inlet of the lean and rich amine liquid heat exchanger (9). A gas outlet is also provided at the top of the flash tank (5). The top inlet of the lean amine liquid cooler (3) is connected to an amine circulation pump (11), and the amine circulation pump (11) is also connected to the lean and rich amine liquid heat exchangers (9). The first outlet at the top of the amine liquid heat exchanger (9) and the amine liquid storage tank are connected. The second outlet at the top of the lean-rich amine liquid heat exchanger (9) is connected to the first inlet at the top of the regeneration tower (10), and the second inlet at the bottom is connected to the bottom outlet of the regeneration tower (10). The top outlet of the regeneration tower (10) is sequentially connected to the acid gas air cooler (13), the top inlet of the acid gas cooler (14), the bottom outlet of the acid gas cooler (14), the top inlet of the regeneration tower reflux tank (15), the bottom outlet of the regeneration tower reflux tank (15), the acid water reflux pump (16) and the second inlet at the top of the regeneration tower (10); the regeneration tower (10) is also connected to a regeneration tower reboiler (12).

2. The natural gas desulfurization and decarbonization equipment according to claim 1, characterized in that: The flash tank (5) is a horizontal tank, and a nitrogen inlet is provided on the top of the flash tank (5) and is connected to a nitrogen filling device.

3. The natural gas desulfurization and decarbonization equipment according to claim 1, characterized in that: The absorption tower (2) and the regeneration tower (10) are plate towers.

4. The natural gas desulfurization and decarbonization equipment according to claim 3, characterized in that: The absorption tower (2) has 14 to 20 plates, and the regeneration tower (10) has 20 to 24 plates.

5. The natural gas desulfurization and decarbonization equipment according to claim 4, characterized in that: The spacing between the plates of the absorption tower (2) and the regeneration tower (10) is 0.6 m. A mist catcher is provided on the top of the tower, and the distance between the top plate and the mist catcher is 0.9 to 1.2 m.

6. The natural gas desulfurization and decarbonization equipment according to claim 1, characterized in that: The natural gas filter (1) is a fiber filter, the lean amine liquid cooler (3) is a shell and tube heat exchanger, and the lean and rich amine liquid heat exchanger (9) is a plate heat exchanger.

7. The natural gas desulfurization and decarbonization equipment according to claim 1, characterized in that: The first-stage filter (6) is a filter element type filter; the second-stage filter (7) is an activated carbon filter; and the third-stage filter (8) is a filter element type filter.

8. The natural gas desulfurization and decarbonization equipment according to claim 1, characterized in that: The acid gas cooler (14) is a shell and tube heat exchanger.

9. The natural gas desulfurization and decarbonization equipment according to any one of claims 1 to 8, characterized in that: The operating temperature of the natural gas filter (1) is 40°C and the operating pressure is 7.0-7.5 MPa; the operating temperature of the absorption tower (2) is 50°C and the operating pressure is 7.0-7.5 MPa; the operating temperature of the flash tank (5) is 50°C and the operating pressure is 0.5 MPa.

10. The natural gas desulfurization and decarbonization equipment according to claim 7, characterized in that: The operating temperature of the primary filter (6), the secondary filter (7) and the tertiary filter (8) is 50°C and the operating pressure is 0.5 MPa.

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