Membrane separation and alcohol amine method natural gas split-flow desulfurization process

Abstract

The invention relates to a membrane separation and alcohol amine method natural gas split-flow desulfurization process. The system comprises a pre-separation module, a first-stage membrane separation module, an alcohol-amine-method shunting desulfurization module and a second-stage membrane separation module. The pre-separation module comprises a gas-liquid separator; the primary membrane separation module comprises a membrane separator and a compressor; the alcohol amine method shunting desulfurization module comprises an absorption tower, a throttle valve, a flash tank, a heat exchanger, a cooler, a circulating pump, a regeneration tower and a regeneration tower bottom reboiler; and the secondary membrane separation module comprises a membrane separator, a compressor, a cooler and a mixer. According to the process, the alcohol amine method natural gas shunting and the secondary separation membrane technology are combined for desulfurization, the finally established system can make the concentration of H2S in the natural gas produced at the top of an absorption tower low, the removal rate of H2S is high, and the comprehensive energy consumption of the device is low. And finally, the H2S content in the gas mixed and output by the mixer is relatively high, so that the total sulfur yield of a downstream sulfur recovery link is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical separation, relates to natural gas deacidification, and specifically relates to a membrane separation and alcoholamine method natural gas splitting and desulfurization process. Background Art

[0002] Natural gas desulfurization is an essential and critical step in natural gas processing, primarily impacting safety, environmental protection, economic efficiency, and process requirements. Hydrogen sulfide (H2S) is a common acidic gas in natural gas that, if not removed, can cause serious harm and problems.

[0003] Natural gas extracted from some gas fields contains significant amounts of hydrogen sulfide (H2S). This highly toxic gas poses a fatal threat to human health even at low concentrations, while high concentrations can cause acute poisoning or even death. Furthermore, H2S can form explosive gases when mixed with air, increasing safety risks during production, transportation, and use.

[0004] Currently, the amine process is widely used in natural gas H2S removal, characterized by high removal efficiency, strong applicability, reversible reaction, and solvent recyclability. With the demand for lower energy consumption, the amine process for diversion H2S removal has also gained widespread application. Methyldiethanolamine (MDEA) is a commonly used amine chemical absorbent in natural gas H2S removal. It offers advantages such as good chemical stability, resistance to degradation, and low H2S removal energy consumption. However, using the amine process alone for diversion H2S removal from natural gas also results in high equipment load and energy consumption.

[0005] Combining the amine-based split-flow H2S removal with a two-stage separation membrane can reduce equipment load and energy consumption. The purified gas after H2S removal has a high degree of purification, and the removed acid gas has a high H2S content, which can greatly improve the total sulfur yield for subsequent sulfur recovery.

[0006] In general, the present invention combines the amine-based split desulfurization with a two-stage separation membrane, which greatly reduces the H2S content in the purified gas, meets the natural gas export standards, reduces equipment load, reduces system energy consumption, has a high desulfurization rate, and improves the total sulfur recovery rate in the subsequent sulfur recovery process. Summary of the Invention

[0007] In response to the problems of heavy equipment load, high operating costs, and high energy consumption in existing natural gas desulfurization technologies, the purpose of the present invention is to provide a membrane separation and amine method natural gas diversion desulfurization process. This process adopts an amine method diversion plus two-stage separation membrane desulfurization technology solution. Compared with other processes, this process reduces equipment load, lowers consumption, has a high desulfurization rate, and has a relatively simple process flow.

[0008] To achieve the above objectives, the present invention provides a membrane separation and alcoholamine natural gas diversion desulfurization process, comprising a pre-separation module, a primary membrane separation module, an alcoholamine diversion desulfurization module, and a secondary membrane separation module.

[0009] The pre-separation module includes a gas-liquid separator V-100; the primary membrane separation module includes a membrane separator OP-1 and a compressor K-101; the amine diversion desulfurization module includes an absorption tower T-100, a throttle valve VLV-100, a flash tank V-101, a heat exchanger E-103, a cooler E-101, a circulating pump P-100, a cooler E-100, a circulating pump P-101, a regeneration tower T-101, and a reboiler H-100 at the bottom of the regeneration tower T-101; the secondary membrane separation module includes a membrane separator OP-2, a compressor K-100, a cooler E-102, and a mixer MIX-100.

[0010] In the pre-separation module, the raw gas inlet pipeline is connected to the gas-liquid separator V-100, the bottom outlet of the gas-liquid separator V-100 separates liquid water, and the top outlet of the gas-liquid separator V-100 is connected to the inlet of the membrane separator OP-1.

[0011] In the first-stage membrane separation module, the top outlet of the gas-liquid separator V-100 is connected to the inlet of the membrane separator OP-1, the lower outlet of the membrane separator OP-1 discharges the retentate gas rich in hydrogen sulfide, the lower outlet of the membrane separator OP-1 is connected to the inlet of the compressor K-101, and the outlet of the compressor K-101 is connected to the inlet of the mixer MIX-100.

[0012] The alcohol amine diversion desulfurization module, the right outlet of the membrane separator OP-1 is connected to the inlet of the absorption tower T-100; the absorption tower T-100 is connected to the throttle valve VLV-100, the flash tank V-101, the heat exchanger E-103, and the regeneration tower T-101 in sequence; the reboiler H-100 at the bottom of the regeneration tower T-101 is connected to the heat exchanger E-103, the cooler E-101, the circulation pump P-100, and the absorption tower T-100 in sequence; the regeneration tower T-101 A portion of the semi-lean liquid flows out from the middle part and is connected to the cooler E-100, the circulation pump P-101, and the middle part of the absorption tower T-100 in sequence through a pipeline; the top outlet of the regeneration tower T-101 is connected to the membrane separator OP-2; the gas rich in hydrogen sulfide is discharged from the top of the regeneration tower T-101; the reboiler H-100 at the bottom of the regeneration tower T-101 produces an amine lean liquid; the top outlet of the flash tank V-101 discharges flash gas; and the top of the absorption tower T-100 discharges natural gas gas.

[0013] In the secondary membrane separation module, the lower outlet of the membrane separator OP-2 discharges permeate gas rich in hydrogen sulfide, and the lower outlet of the membrane separator OP-2 is connected to the inlet of the mixer MIX-100; the right outlet of the membrane separator OP-2 discharges permeate gas from which some hydrogen sulfide has been removed, and the right outlet of the membrane separator OP-2 is connected to the compressor K-100 and the cooler E-102 in sequence; the mixer MIX-100 mixes and transports the permeate gas rich in hydrogen sulfide from the compressor K-101 and the lower outlet of the membrane separator OP-2.

[0014] The above-mentioned membrane separation and amine-based natural gas splitting and desulfurization process is applicable to a wide range of raw gas conditions. The raw gas is room temperature, high-pressure natural gas with a high H2S content.

[0015] The above-mentioned membrane separation and amine-based natural gas split desulfurization process includes a heat exchanger including heat exchanger E-103, which is a conventional device in the field and primarily functions to achieve heat exchange and transfer during the production process. In the present invention, a first heat exchange channel is provided within heat exchanger E-103;

[0016] The bottom pipe of the flash tank V-101 is connected to the head end of the first heat exchange channel, and the end of the first heat exchange channel is connected to the regeneration tower T-101 through a pipe.

[0017] The above membrane separation and amine-based natural gas split desulfurization process consists of an absorption tower T-100, a throttle valve VLV-100, a flash tank V-101, a heat exchanger E-103, a regeneration tower T-101, a reboiler H-100 at the bottom of the regeneration tower T-101, a heat exchanger E-103, a cooler E-101, a circulating pump P-100, and a semi-lean liquid partially discharged from the regeneration tower T-101. The semi-lean liquid is piped through the cooler E-100, the circulating pump P-101, and the absorption tower T-100 to form an amine-based natural gas split desulfurization circuit. The retentate gas rich in hydrogen sulfide is discharged from the outlet below the membrane separator OP-1. The gas is transported to compressor K-101 through a pipeline, and the outlet of compressor K-101 is connected to the inlet of mixer MIX-100, forming a primary membrane separation hydrogen sulfide circuit; the top outlet of regeneration tower T-101 is connected to the inlet of membrane separator OP-2, and the gas transported to compressor K-100, cooler E-102 and the right outlet of membrane separator OP-1 through a pipeline are combined and sent to absorption tower T-100, forming a secondary membrane deep separation hydrogen sulfide circuit; mixer MIX-100 mixes and transports the hydrogen sulfide-rich retentate gas from compressor K-101 and the lower outlet of membrane separator OP-2.

[0018] In the above-mentioned membrane separation and amine-based natural gas split desulfurization process, the two-stage membrane separation usually uses modified polyimide as the membrane material. This material has a high H2S permeability and a large permeability factor, and is therefore widely used in industry. Membrane separation relies on the difference in the solubility or diffusion rate of H2S on both sides of the separation membrane to achieve the purpose of desulfurization.

[0019] In the above membrane separation and alcoholamine method natural gas splitting and desulfurization process, the two-stage separation membrane uses modified polyimide as the membrane material.

[0020] In the above-mentioned membrane separation and amine-based natural gas split desulfurization process, the reboiler H-100 at the bottom of the regeneration tower T-101 adopts a directly fired heating furnace as a heat source.

[0021] In the above membrane separation and amine-based natural gas split desulfurization process, MDEA is used as the absorbent in the present invention because of its advantages of good chemical stability, resistance to degradation and low energy consumption for H2S removal.

[0022] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0023] (1) The present invention provides a membrane separation and amine-based natural gas split desulfurization process, including an amine-based split desulfurization module. The amine-based split desulfurization process improves H2S recovery. The H2S-rich retentate gas removed by the primary separation membrane is then transported to a mixer and mixed with the H2S-rich retentate gas removed by the secondary separation membrane. The mixed gas has a high H2S content. The integration of the two processes reduces equipment load, investment, and energy consumption, and improves the total sulfur recovery rate in the downstream sulfur recovery process.

[0024] (2) The present invention provides a membrane separation and amine method natural gas diversion desulfurization process. The desulfurization process adopts amine method natural gas diversion plus secondary separation membrane technology. The produced natural gas has a low H2S concentration, a high H2S removal rate, low overall energy consumption of the device, a simple process flow, and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a process flow chart of membrane separation and alcoholamine method natural gas splitting and desulfurization process of the present invention;

[0026] Explanation of the accompanying symbols: V-100-gas-liquid separator; OP-1-membrane separator; T-100-absorption tower; VLV-100-throttle valve; V-101-flash tank; E-103-heat exchanger; T-101-regeneration tower; H-100-regeneration tower reboiler; E-100-cooler; P-101-circulation pump; E-101-cooler; P-100-circulation pump; K-101-compressor; MIX-100-mixer; OP-2-membrane separator; K-100-compressor; E-102-cooler. DETAILED DESCRIPTION

[0027] The following will be combined with the attached Figure 1 The membrane separation and alcoholamine method natural gas splitting and desulfurization process provided by the present invention is clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention.

[0028] This embodiment provides a membrane separation and alcohol amine method natural gas splitting desulfurization process, such as Figure 1 As shown, it includes a pre-separation module, a primary membrane separation module, an amine diversion desulfurization module, and a secondary membrane separation module connected by pipelines.

[0029] The pre-separation module includes a gas-liquid separator V-100.

[0030] The first-stage membrane separation module includes a membrane separator OP-1 and a compressor K-101.

[0031] The amine diversion desulfurization module includes absorption tower T-100, throttle valve VLV-100, flash tank V-101, heat exchanger E-103, cooler E-101, circulation pump P-100, cooler E-100, circulation pump P-101, regeneration tower T-101, and reboiler H-100 at the bottom of regeneration tower T-101; the secondary membrane separation module includes membrane separator OP-2, compressor K-100, cooler E-102, and mixer MIX-100.

[0032] The raw gas inlet pipeline is connected to the gas-liquid separator V-100, and liquid water is separated from the bottom outlet of the gas-liquid separator V-100. The top outlet of the gas-liquid separator V-100 is connected to the inlet of the membrane separator OP-1 to remove H2S. The H2S-rich retentate gas discharged from the bottom outlet of the membrane separator OP-1 is pressurized by the compressor K-101 and then transported to the mixer MIX-100; the gas with a large amount of H2S removed on the right side of the membrane separator OP-1 enters the absorption tower T-100 from the bottom and reacts with the lean amine liquid entering from the top of the absorption tower T-100; the natural gas after the reaction is discharged from the top of the absorption tower T-100 and enters the next-level natural gas purification module; the lean amine liquid that absorbs H2S becomes an alcohol amine-rich liquid and is discharged from the bottom of the absorption tower T-100, throttled by the throttle valve VLV-100, and enters the flash tank V-101, and the flash gas component is discharged from the top outlet of the flash tank V-101.

[0033] The rich alcoholamine solution is discharged from the bottom of flash tank V-101 and enters heat exchanger E-103, where it undergoes heat exchange with the lean alcoholamine solution from regeneration tower T-101. The heated rich alcoholamine solution then enters regeneration tower T-101 for regeneration. The regenerated lean alcoholamine solution, exiting reboiler H-100 at the bottom of regeneration tower T-101, is cooled in heat exchanger E-103 and cooler E-101, pressurized by circulating pump P-100, and supplemented with water and MDEA before circulating through the top of absorption tower T-100. The semi-lean solution flowing out of regeneration tower T-101 is cooled in cooler E-100, pressurized by circulating pump P-101, and then enters the middle section of absorption tower T-100, thereby reducing the operating load and energy consumption of absorption tower T-100 and subsequent equipment.

[0034] The H2S-rich gas discharged from the top outlet of the regeneration tower T-101 enters the left inlet of the membrane separator OP-2 for deep H2S removal. The permeate gas containing a small amount of unremoved H2S discharged from the right outlet of the membrane separator OP-2 is pressurized by the compressor K-100, cooled by the cooler E-102, and mixed with the gas from the right side of the membrane separator OP-1 before entering the bottom of the absorption tower T-100 for circulation; the H2S-rich retentate gas discharged from the bottom outlet of the membrane separator OP-2 and the H2S-rich retentate gas discharged from the bottom outlet of the membrane separator OP-1 enter the mixer MIX-100 for mixing and then transported to the downstream sulfur recovery link.

[0035] In the above-mentioned membrane separation and amine-based natural gas split desulfurization process, the two-stage membrane separation usually uses modified polyimide as the membrane material. This material has a high H2S permeability and a large permeability factor, and is therefore widely used in industry. Membrane separation relies on the difference in the solubility or diffusion rate of H2S on both sides of the separation membrane to achieve the purpose of desulfurization.

[0036] In the above membrane separation and alcoholamine method natural gas splitting and desulfurization process, the two-stage separation membrane uses modified polyimide as the membrane material.

[0037] In the above-mentioned membrane separation and amine-based natural gas split desulfurization process, the reboiler H-100 at the bottom of the regeneration tower T-101 adopts a directly fired heating furnace as a heat source.

[0038] In the above membrane separation and amine-based natural gas split desulfurization process, MDEA is used as the absorbent in the present invention because of its advantages of good chemical stability, resistance to degradation and low energy consumption for H2S removal.

[0039] The above-mentioned membrane separation and amine-based natural gas splitting and desulfurization process is applicable to a wide range of raw gas conditions. The raw gas is room temperature, high-pressure natural gas with a high H2S content.

[0040] The above embodiments are intended to help readers understand the principles of the present invention, and the scope of protection of the present invention is not limited to such specific descriptions and embodiments. For those skilled in the art, various combinations and improvements can be made without departing from the principles of the present invention, and these combinations and improvements are also within the scope of protection of the present invention.

Claims

1. A membrane separation and alcoholamine natural gas split desulfurization process, comprising a pre-separation module, a primary membrane separation module, an alcoholamine split desulfurization module, and a secondary membrane separation module; The pre-separation module includes a gas-liquid separator V-100; the first-level membrane separation module includes a membrane separator OP-1 and a compressor K-101; the amine diversion desulfurization module includes an absorption tower T-100, a throttle valve VLV-100, a flash tank V-101, a heat exchanger E-103, a cooler E-101, a circulating pump P-100, a cooler E-100, a circulating pump P-101, a regeneration tower T-101, and a reboiler H-100 at the bottom of the regeneration tower T-101; the second-level membrane separation module includes a membrane separator OP-2, a compressor K-100, a cooler E-102, and a mixer MIX-100. In the pre-separation module, the raw gas inlet pipeline is connected to the gas-liquid separator V-100, the bottom outlet of the gas-liquid separator V-100 separates liquid water, and the top outlet of the gas-liquid separator V-100 is connected to the inlet of the membrane separator OP-1; In the primary membrane separation module, the top outlet of the gas-liquid separator V-100 is connected to the inlet of the membrane separator OP-1, the lower outlet of the membrane separator OP-1 discharges the retentate gas rich in hydrogen sulfide, the lower outlet of the membrane separator OP-1 is connected to the inlet of the compressor K-101, and the outlet of the compressor K-101 is connected to the inlet of the mixer MIX-100; The alcohol amine diversion desulfurization module, the right outlet of the membrane separator OP-1 is connected to the inlet of the absorption tower T-100; the absorption tower T-100 is connected to the throttle valve VLV-100, the flash tank V-101, the heat exchanger E-103, and the regeneration tower T-101 in sequence; the reboiler H-100 at the bottom of the regeneration tower T-101 is connected to the heat exchanger E-103, the cooler E-101, the circulation pump P-100, and the absorption tower T-100 in sequence; the regeneration tower T-101 A portion of the semi-lean liquid flows out from the middle part and is connected to the cooler E-100, the circulation pump P-101, and the middle part of the absorption tower T-100 in sequence through a pipeline; the top outlet of the regeneration tower T-101 is connected to the membrane separator OP-2; the gas rich in hydrogen sulfide is discharged from the top of the regeneration tower T-101; the reboiler H-100 at the bottom of the regeneration tower T-101 produces an amine lean liquid; the top outlet of the flash tank V-101 discharges flash gas; and the top of the absorption tower T-100 discharges natural gas gas. In the secondary membrane separation module, the lower outlet of the membrane separator OP-2 discharges permeate gas rich in hydrogen sulfide, and the lower outlet of the membrane separator OP-2 is connected to the inlet of the mixer MIX-100; the right outlet of the membrane separator OP-2 discharges permeate gas from which part of the hydrogen sulfide has been removed, and the right outlet of the membrane separator OP-2 is connected to the compressor K-100 and the cooler E-102 in sequence; the mixer MIX-100 mixes and transports the permeate gas rich in hydrogen sulfide from the compressor K-101 and the lower outlet of the membrane separator OP-2.

2. The membrane separation and alcoholamine method natural gas splitting and desulfurization process according to claim 1, characterized in that: The heat exchanger E-103 is provided with a first heat exchange channel; The bottom pipe of the flash tank V-101 is connected to the head end of the first heat exchange channel, and the end of the first heat exchange channel is connected to the regeneration tower T-101 through a pipe.

3. The membrane separation and alcoholamine method natural gas splitting and desulfurization process according to claim 1, characterized in that: The membrane separator OP-1 is provided with a left inlet channel, a right outlet channel, and a bottom outlet channel; The top outlet of the gas-liquid separator V-100 is connected to the left inlet of the membrane separator OP-1 to remove H2S. The retentate gas rich in H2S is discharged from the bottom outlet of the membrane separator OP-1 and is pressurized by the compressor K-101 and then transported to the mixer MIX-100. The gas with a large amount of H2S removed from the right outlet of the membrane separator OP-1 enters the absorption tower T-100 from the bottom and reacts with the lean amine liquid entering from the top of the absorption tower T-100.

4. The membrane separation and alcoholamine method natural gas splitting and desulfurization process according to claim 1, characterized in that: The membrane separator OP-2 is provided with a left inlet channel, a right outlet channel, and a bottom outlet channel; The H2S-rich gas discharged from the top outlet of the regeneration tower T-101 enters the left inlet of the membrane separator OP-2 for deep H2S removal. The permeate gas containing a small amount of unremoved H2S discharged from the right outlet of the membrane separator OP-2 is pressurized by the compressor K-100, cooled by the cooler E-102, mixed with the gas from the right outlet of the membrane separator OP-1, and then enters the bottom of the absorption tower T-100 for circulation; the H2S-rich retentate gas discharged from the bottom outlet of the membrane separator OP-2 and the H2S-rich retentate gas discharged from the bottom outlet of the membrane separator OP-1 enter the mixer MIX-100 for mixing and transportation.

5. A membrane separation and alcoholamine method natural gas splitting and desulfurization process according to any one of claims 1 to 4, characterized in that: The two-stage membrane separation is a membrane separator OP-1 and a membrane separator OP-2 for natural gas desulfurization, and the membrane material is modified polyimide.

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