Apparatus and method for recovering hydrogen sulfide from a sour gas

Abstract

The application relates to a device for recycling hydrogen sulfide in sour gas, which comprises a primary absorber, an acid gas inlet and an amine liquid inlet arranged on the primary absorber, a secondary absorber, a gas-liquid separation section and an absorption section, the gas-liquid separation section being communicated with the primary absorber, the lower end of the absorption section being provided with an amine liquid outlet, the lower end of the gas-liquid separation section being provided with an amine liquid outlet, a tertiary absorber communicated with the upper end of the secondary absorber, the tertiary absorber being provided with an amine liquid inlet, a gas-liquid separator communicated with the tertiary absorber, the gas-liquid separator being provided with a purified gas outlet and an amine liquid outlet, and the primary amine liquid, the secondary amine liquid and the secondary semi-amine liquid are all amine-containing solutions. The application has the advantages of high amine utilization rate and low public engineering consumption.

Description

Technical Field

[0001] This application relates to the fields of chemical engineering and environmental protection technology, and in particular to an apparatus and method for recovering acidic gases containing hydrogen sulfide generated in chemical processes. Background Technology

[0002] The refinery gas, natural gas, and syngas involved in the fields of oil refining, chemical engineering, and environmental protection all contain acidic components such as hydrogen sulfide and carbon dioxide, as well as other components such as hydrocarbons, water, and ammonia. Currently, the main treatment method is to first separate hydrogen sulfide from these refinery gases, natural gas, and syngas, and then use the hydrogen sulfide as a raw material to produce chemical products such as sulfur, sulfuric acid, sodium hydrosulfide, thiophenol, and thiourea.

[0003] Industrial application practices have shown that excessive carbon dioxide in hydrogen sulfide can adversely affect the production of the aforementioned chemical products. For example, when used in sulfur production, carbon dioxide dilutes the concentration of hydrogen sulfide in the acid gas, lowers the temperature of the acid gas combustion furnace, and reacts with hydrogen sulfide to generate excessive COS and CS2, leading to a decrease in product quality. When used in the production of NaHS, carbon dioxide easily reacts with NaOH to generate Na2CO3. Na2CO3 not only reduces the quality of NaHS products but also combines with H2O to form crystals such as Na2CO3·9H2O, which can clog equipment and pipelines, affecting normal production. Excessive hydrocarbons in hydrogen sulfide can also adversely affect the production of the aforementioned chemical products. For example, when used in sulfur production, hydrocarbons can easily cause overheating of the sulfur combustion furnace and a sharp increase in CS2 generation. Incomplete combustion of hydrocarbons can also produce black sulfur. Therefore, purifying hydrogen sulfide in acid gas is crucial for improving product quality and ensuring normal production of the equipment.

[0004] Currently, hydrogen sulfide is generally absorbed by alkaline liquids, but this method has several problems: the process is complex, and the equipment and operating costs are high; the purity of the recovered hydrogen sulfide product is low and cannot meet the requirements of actual production; the hydrogen sulfide recovery rate in the hydrogen sulfide product is low, and the hydrogen sulfide content in the purified gas cannot meet the requirements of relevant standards. Summary of the Invention

[0005] This application provides an apparatus and method for recovering hydrogen sulfide from acidic gas, in order to solve the technical problem that amine liquid carries too much carbon dioxide, hydrocarbons and other substances when absorbing hydrogen sulfide from acidic gas.

[0006] In a first aspect, embodiments of this application provide an apparatus for recovering hydrogen sulfide from acidic gas, comprising:

[0007] A primary absorber, wherein the primary absorber is provided with an acid gas inlet and a primary amine liquid inlet;

[0008] A secondary absorber includes a gas-liquid separation section and m absorption sections distributed from bottom to top inside the absorber, wherein m is not less than 1. The gas-liquid separation section is connected to the primary absorber. The upper end of the absorption section is provided with a first inlet of secondary amine liquid and the lower end is provided with a first outlet of secondary half amine liquid. The lower end of the gas-liquid separation section is provided with an outlet of primary sulfur-rich amine liquid.

[0009] A tertiary absorber is connected to the upper end of the secondary absorber, and a second inlet for secondary amine liquid is provided on the tertiary absorber;

[0010] A gas-liquid separator, wherein the three-stage absorber is connected to the gas-liquid separator, and the gas-liquid separator is provided with a purified gas outlet and a second outlet for the secondary half amine liquid;

[0011] The first outlet and the second outlet of the secondary halfamine liquid are connected to the inlet of the primary amine liquid. The secondary halfamine liquids discharged from the first outlet and the second outlet of the secondary halfamine liquid are combined into the primary amine liquid and input into the inlet of the primary amine liquid.

[0012] The primary amine solution, secondary amine solution, and secondary semiamine solution are all solutions containing amine substances.

[0013] In some embodiments of this application, the tertiary absorber is further connected to an exogenous amine solution inlet tube, wherein the exogenous amine solution is a solution containing amine substances.

[0014] In some embodiments of this application, the purified gas outlet is connected to a purified gas outlet pipe, and a first hydrogen sulfide content analyzer is installed on the purified gas outlet pipe; a first regulating valve is installed on the exogenous amine liquid inlet pipe, and the first hydrogen sulfide content analyzer and the first regulating valve are connected and controlled by pneumatic or electric signals.

[0015] In some embodiments of this application, a mass transfer internal is disposed within the absorption section; let 1≤i≤m, the number of mass transfer units on the mass transfer internal in the i-th absorption section distributed from bottom to top is N. i Among them are:

[0016] N i =ln(C ii / C io )

[0017] C ii C is the molar fraction of hydrogen sulfide in the acid gas feed of the i-th absorption section; io The amount fraction of hydrogen sulfide in the acidic gas output of the i-th absorption section.

[0018] In some embodiments of this application, C ii and Cio Calculated as follows:

[0019]

[0020] C ii =C i / k (i-1)

[0021] c io =C i / k i

[0022] Among them, C i C represents the molar fraction of hydrogen sulfide in the acidic gas entering the gas-liquid separation section from the primary absorber. o The amount of hydrogen sulfide in the acidic gas entering the tertiary absorber from the upper end of the secondary absorber.

[0023] In some embodiments of this application, the apparatus for recovering hydrogen sulfide from acidic gas further includes a flash evaporator, the primary sulfur-rich amine liquid outlet is connected to the flash evaporator, the lower part of the flash evaporator is provided with a secondary sulfur-rich amine liquid outlet, and the upper part of the flash evaporator is provided with a flash vapor outlet.

[0024] In some embodiments of this application, the upper part of the flash evaporator is provided with a third inlet for secondary amine liquid.

[0025] In some embodiments of this application, the flash vapor outlet is connected to a flash vapor outlet pipe and a flash vapor circulation pipe, with one end of the flash vapor circulation pipe connected to the flash vapor outlet and the other end connected to the flash evaporator.

[0026] In some embodiments of this application, a second regulating valve is provided at the third inlet of the secondary amine liquid, a third regulating valve is provided on the flash vapor circulation pipe, and a second hydrogen sulfide content analyzer is provided on the flash vapor outlet pipe. The second hydrogen sulfide content analyzer is connected and controlled by the second regulating valve and the third regulating valve via pneumatic or electric signals.

[0027] In some embodiments of this application, the apparatus for recovering hydrogen sulfide from acidic gas further includes a regeneration tower, and the outlet of the secondary sulfur-rich amine liquid is connected to the regeneration tower;

[0028] The lower part of the regeneration tower is connected to a reboiler for heating the liquid flow inside the regeneration tower, the upper part of the regeneration tower is provided with a first hydrogen sulfide outlet, and the bottom of the regeneration tower is provided with a regenerated amine liquid outlet.

[0029] In some embodiments of this application, the apparatus for recovering hydrogen sulfide from acidic gas further includes a condenser and a reflux tank, the top of the regeneration tower is connected to the condenser, the condenser is connected to the reflux tank, and the reflux tank is connected to the upper part of the regeneration tower; a second hydrogen sulfide outlet is provided on the reflux tank.

[0030] In some embodiments of this application, the apparatus for recovering hydrogen sulfide from acidic gas further includes a second cooler and a filter, wherein the regenerated amine liquid outlet, the second cooler, and the filter are sequentially connected; the filter is connected to the second secondary amine liquid inlet, the third secondary amine liquid inlet, and the filter is also provided with a secondary amine liquid discharge outlet.

[0031] In some embodiments of this application, the regenerated amine liquid outlet is connected to the second cooler via a first pipe and a second pipe in parallel, wherein a portion of the first pipe is disposed inside the bottom of the flash evaporator.

[0032] In some embodiments of this application, a thermometer for monitoring the internal temperature is provided at the bottom of the flash evaporator, a fourth regulating valve is provided on the first pipeline, and a fifth regulating valve is provided on the second pipeline. The thermometer is connected to and controlled by the fourth and fifth regulating valves via pneumatic or electric signals.

[0033] In some embodiments of this application, the second cooler is also connected to a deoxygenated water inlet pipe.

[0034] Secondly, embodiments of this application also provide a method for recovering hydrogen sulfide from acidic gas, comprising the following steps:

[0035] Provides acidic gas containing hydrogen sulfide and carbon dioxide;

[0036] The acid gas is treated by the apparatus for recovering hydrogen sulfide from the acid gas as described in the first aspect.

[0037] In some embodiments of this application, the primary amine solution, secondary amine solution, and secondary half-amine solution are all solutions containing MDEA.

[0038] In some embodiments of this application, the acidic gas load of the secondary amine solution in the absorption section is 0.25–0.55, or,

[0039] The primary purified gas introduced into the absorption section and the secondary amine liquid introduced into the absorption section have a gas-liquid ratio of 10 to 1000.

[0040] In some embodiments of this application, the acidic gas load of the secondary amine liquid in the flash evaporator is 0.20 to 0.50.

[0041] The technical solutions provided in this application have the following advantages compared with the prior art:

[0042] The apparatus and method for recovering hydrogen sulfide from acidic gas provided in this application embodiment highly couples equipment such as a primary absorber, a secondary absorber, and a tertiary absorber, and uses primary and secondary amine solutions containing amines to absorb hydrogen sulfide. This enables cascaded, highly selective absorption of hydrogen sulfide from acidic gas under very short reaction times. The recovered hydrogen sulfide product has high purity, and the secondary semi-lean amine solution can be combined into a primary amine solution for reuse, resulting in high amine utilization and low utility consumption. Attached Figure Description

[0043] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A schematic diagram of a device for recovering hydrogen sulfide from acidic gas, provided in an embodiment of this application;

[0046] Figure 2 A schematic diagram of the cross-sectional structure of the absorption section provided in an embodiment of this application;

[0047] Figure 3 This is a schematic diagram of the longitudinal cross-sectional structure of the absorption section provided in an embodiment of this application.

[0048] In the diagram: 01-First-stage absorber; 011-Acid gas inlet; 012-First-stage amine liquid inlet; 02-First cooler; 03-Second-stage absorber; 031-Gas-liquid separation section; 032-First absorption section; 033-Second absorption section; 034-Third absorption section; 035-First inlet of second-stage amine liquid; 036-First outlet of second-stage half-amine liquid; 037-Outlet of first-stage sulfur-rich amine liquid; 04-Third-stage absorber; 041-Second-stage amine liquid Second inlet; 042-Exogenous amine liquid inlet pipe; 05-Gas-liquid separator; 051-Purified gas outlet; 052-Secondary half-amine liquid second outlet; 053-Purified gas outlet pipe; 06-Flash evaporator; 061-Flash evaporator; 062-First flash evaporation section; 063-Second flash evaporation section; 064-Circulating water cooler; 065-Secondary sulfur-rich amine liquid outlet; 066-Flash vapor outlet; 067-Secondary amine liquid third inlet; 068- Flash vapor outlet pipe; 069-Flash vapor circulation pipe; 07-First pumping device; 08-Regeneration tower; 081-Reboiler; 082-Condenser; 083-Reflux tank; 084-Second pumping device; 085-First hydrogen sulfide outlet; 086-Regenerated amine liquid outlet; 087-Second hydrogen sulfide outlet; 09-Third pumping device; 091-Deoxygenated water inlet pipe; 10-Second cooler; 11-Filter; 111-Secondary amine liquid Discharge port; 12-Gas compressor; 131-First hydrogen sulfide content analyzer; 132-First regulating valve; 141-Second hydrogen sulfide content analyzer; 142-Second regulating valve; 143-Third regulating valve; 151-Thermometer; 152-Fourth regulating valve; 153-Fifth regulating valve; 154-First pipeline; 155-Second pipeline; 16-Gas chamber; 17-Liquid chamber; 171-Liquid collection tank; 18-Gas riser pipe; 181-Rain cap. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0050] Unless otherwise specified, the terminology used in this specification should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In the event of any conflict, this specification shall prevail.

[0051] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0052] Existing amine solutions have technical problems in absorbing hydrogen sulfide from acidic gases, such as entraining excessive amounts of carbon dioxide and hydrocarbons.

[0053] The technical solution provided in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0054] In a first aspect, embodiments of this application provide an apparatus for recovering hydrogen sulfide from acidic gas, comprising:

[0055] A primary absorber 01 is provided with an acid gas inlet 011 and a primary amine liquid inlet 012.

[0056] The secondary absorber 03 includes a gas-liquid separation section 031 and m absorption sections distributed from bottom to top inside it, wherein m is not less than 1. The gas-liquid separation section 031 is connected to the primary absorber 01. The upper end of the absorption section is provided with a first inlet 035 for secondary amine liquid and a first outlet 036 for secondary half amine liquid. The lower end of the gas-liquid separation section 031 is provided with a first outlet 037 for primary sulfur-rich amine liquid.

[0057] The third-stage absorber 04 is connected to the upper end of the second-stage absorber 03, and the third-stage absorber 04 is provided with a second inlet 041 for the second-stage amine liquid.

[0058] Gas-liquid separator 05, the three-stage absorber 04 is connected to the gas-liquid separator 05, and the gas-liquid separator 05 is provided with a purified gas outlet 051 and a secondary half amine liquid outlet 052.

[0059] The first outlet 036 and the second outlet 052 of the secondary halfamine liquid are connected to the inlet 012 of the primary amine liquid. The secondary halfamine liquids discharged from the first outlet 036 and the second outlet 052 of the secondary halfamine liquid are combined into the primary amine liquid and input into the inlet 012 of the primary amine liquid.

[0060] The primary amine solution, secondary amine solution, and secondary semiamine solution are all solutions containing amine substances.

[0061] The amine solution described in this application, also known as lean amine solution, is used to absorb hydrogen sulfide during the desulfurization process of acidic gas. It generally includes organic base and a small amount of additives such as antifoaming agents, corrosion inhibitors, antioxidants, and activators, as needed.

[0062] As a preferred embodiment, the amine substance can be MDEA (N-methyldiethanolamine).

[0063] The hydrogen sulfide and carbon dioxide in the acidic gas react with the MDEA solution in the amine liquid as follows:

[0064] The reaction of MDEA solution with hydrogen sulfide is briefly described below.

[0065] MDEA reacts with hydrogen sulfide through the unpaired electrons on its nitrogen atom, exhibiting basicity. This reaction is a proton-transfer reaction, completed instantaneously, and the reaction equation is as follows:

[0066] H₂S + R₁R₂N → R₁R₂NH + +HS -

[0067] The reaction of MDEA solution with carbon dioxide is briefly described below.

[0068] The reaction between carbon dioxide and MDEA is complex and can only occur in the presence of water.

[0069]

[0070] The reaction between MDEA and H2S is instantaneous, and H2S rapidly crosses the interface into the bulk liquid phase. However, the reaction between MDEA solution and carbon dioxide is slower because carbon dioxide molecules lack ionizable protons. Carbon dioxide first enters the gas film from the gas phase, then crosses the gas-liquid interface into the liquid film, and finally enters the bulk liquid phase, where it reacts with OH-. - The reaction forms HCO3 - Ions, HCO3 - The ions then react with MDEA, thus the reaction between carbon dioxide and MDEA is a slow reaction controlled by the liquid film. This difference in the reaction rate of MDEA with H2S and CO2 can be used to increase the concentration of hydrogen sulfide in acidic gas feedstocks, i.e., to purify hydrogen sulfide in acidic gases. Specifically, measures such as changing the contact time, contact area, and contact temperature between hydrogen sulfide and carbon dioxide and the MDEA solution can be taken to improve the selective absorption capacity of the MDEA solvent, making the absorption of acidic gases by MDEA more favorable to hydrogen sulfide and less favorable to carbon dioxide.

[0071] In some embodiments of this application, the acidic gas originates from the boundary outside the device and contains components such as hydrogen sulfide and carbon dioxide.

[0072] In some embodiments of this application, the acid gas temperature is 30–50°C and the pressure is 1.0–5.0 MPa.

[0073] In some embodiments of this application, the amine solution may be a MDEA (N-methyldiethanolamine) solution with a mass fraction of 25% to 50%, or it may be a composite MDEA solution with a small amount of additives such as antifoaming agents, corrosion inhibitors, antioxidants, activators, etc. added to further improve the solvent performance.

[0074] In this application, acidic gas enters the primary absorber 01 through the acidic gas inlet 011, and primary amine liquid enters the primary absorber 01 through the primary amine liquid inlet 012. In the primary absorber 01, hydrogen sulfide in the acidic gas is selectively absorbed by the primary amine liquid. The primary absorber 01 can be a static mixer, an injector, or other similar device, and an injector is preferred. The injector consists of four sequentially connected parts: a nozzle, a receiving chamber, a mixing chamber, and a diffusion chamber. The acidic gas inlet 011 and the primary amine liquid inlet 012 are respectively located at the nozzle and the receiving chamber. When acidic gas with a certain pressure is injected through the nozzle, a high flow velocity is generated, forming a low-pressure zone around the nozzle. This allows primary amine liquid to be drawn into the nozzle and injected together with the acidic gas into the receiving chamber. In the receiving chamber, the two undergo preliminary mixing, then enter the mixing chamber where they are fully mixed and turbulent, simultaneously undergoing a hydrogen sulfide removal reaction. Next, the gas enters the diffusion chamber. In general, the diameter of the diffusion chamber gradually increases with the direction of fluid movement, and the flow velocity of the reaction mixture gradually decreases. This process converts kinetic energy into pressure energy, allowing the pressure at the diffusion chamber outlet to reach the pressure required by subsequent equipment. This eliminates the need for pumps and other pressurization equipment, simplifying the process. The nozzle is preferably a converging single nozzle, preferably conical, with a cone angle preferably between 6° and 12°. The receiving chamber provides sufficient contact space for the gas and liquid phases, ensuring initial and unobstructed mixing. The mixing chamber primarily handles mass and heat transfer between the gas and liquid phases. The design of its throat length and diameter should balance mass transfer efficiency and resistance drop; preferably, the ratio of throat length to diameter is controlled between 3 and 10. The diffusion chamber converts kinetic energy into pressure energy and allows mass and heat transfer to continue. Preferably, the ratio of its length to the mixing chamber throat diameter is controlled between 6 and 16, and the diffusion angle is preferably between 6° and 8°. The primary absorber 01, using an ejector, can complete gas-liquid mass transfer in a very short time, which is highly advantageous for the selective absorption of hydrogen sulfide from acidic gas by the amine liquid.

[0075] Within the primary absorber 01, the contact time between the gas and liquid phases is controlled within the range of 0.01 to 1.00 seconds, minimizing the absorption rate of carbon dioxide while ensuring the absorption rate of hydrogen sulfide.

[0076] In the primary absorber 01, 20.0% to 80.0% of the hydrogen sulfide in the acid gas is absorbed by the primary amine liquid; after absorbing part of the hydrogen sulfide in the acid gas, the primary amine liquid forms a gas-liquid mixture with the remaining acid gas and is introduced into the gas-liquid separation section 031.

[0077] In some embodiments of this application, the apparatus for recovering hydrogen sulfide from acidic gas further includes a first cooler 02, and the primary absorber 01 is connected to the gas-liquid separation section 031 through the first cooler 02.

[0078] The gas-liquid mixture is discharged from the primary absorber 01 and enters the first cooler 02 to be cooled to 30-50°C, and then enters the gas-liquid separation section 031 of the secondary absorber 03. In the gas-liquid separation section 031, the gas-liquid mixture is subjected to adiabatic flash evaporation, and the separated gas is used as primary purified gas to enter the absorption section of the secondary absorber 03 from the upper part of the gas-liquid separation section 031.

[0079] In this application, the secondary absorber 03 includes a gas-liquid separation section 031 and m absorption sections distributed from bottom to top inside, where m is not less than 1. This means the secondary absorber 03 can have at least one absorption section of any number. The number of absorption sections in the secondary absorber 03 is generally set to 1 to 6, meaning m is generally a number from 1 to 6. As an example, let m = 3, and the three absorption sections are, from bottom to top, the first absorption section 032, the second absorption section 033, and the third absorption section 034. The primary amine liquid and the gas-liquid mixture undergo gas-liquid separation in the gas-liquid separation section 031. The separated gas is denoted as the primary purified gas. The primary purified gas flows upward and sequentially enters the first absorption section 032, the second absorption section 033, and the third absorption section 034 of the secondary absorber 03, respectively, and comes into countercurrent contact with the secondary amine liquid in the first absorption section 032, the second absorption section 033, and the third absorption section 034. The upper ends of the first absorption section 032, the second absorption section 033, and the third absorption section 034 are all provided with a first inlet 035 for secondary amine liquid, through which the secondary amine liquid is introduced. 60.0%–95.0% of the hydrogen sulfide contained in the primary purified gas is removed, and then the gas is discharged from the upper end of the secondary absorber 03 as secondary purified gas, entering the tertiary absorber 04 for further hydrogen sulfide removal. The secondary amine liquid, after absorbing the hydrogen sulfide in the primary purified gas, is discharged as secondary half-amine liquid from the first outlet 036 of the secondary half-amine liquid. The lower ends of the first absorption section 032, the second absorption section 033, and the third absorption section 034 are all provided with a first outlet 036 for secondary amine liquid. The liquid separated by the gas-liquid separation section 031 of the secondary absorber 03, i.e., the primary sulfur-rich amine liquid, is discharged from the primary sulfur-rich amine liquid outlet 037 at the lower end of the gas-liquid separation section 031 of the secondary absorber 03.

[0080] The tertiary absorber 04 can be equipped with a static mixer, injector, or other devices, with a static mixer being preferred. Static mixers offer advantages such as good mixing performance, high efficiency, high operational flexibility, simple structure, small size, small footprint, low risk of damage, and low equipment and operating costs. The secondary purified gas enters the tertiary absorber 04 under its own kinetic energy, while the secondary amine liquid enters the tertiary absorber 04 through the second inlet 041. The secondary purified gas and secondary amine liquid flow within the tertiary absorber 04, undergoing cutting, twisting, separation, mixing, and reaction during the flow. Both diversion and radial mixing occur simultaneously, effectively removing 80.0%–95.0% of the hydrogen sulfide from the secondary purified gas.

[0081] The three-stage absorber 04 is preferably an SX or SV type static mixer, with the length / diameter ratio (L / D) controlled within the range of 5 to 15;

[0082] Within the three-stage absorber 04, the contact time between the gas and liquid phases is controlled within the range of 0.02 to 2.00 seconds, so as to minimize the absorption rate of carbon dioxide while ensuring the absorption rate of hydrogen sulfide.

[0083] Within the tertiary absorber 04, 80.0%–95.0% of the hydrogen sulfide in the secondary purified gas is absorbed by the secondary amine liquid. The secondary amine liquid, after absorbing the hydrogen sulfide from the secondary purified gas, becomes the secondary half-amine liquid. A portion of the hydrogen sulfide in the secondary purified gas is absorbed by the secondary amine liquid and becomes the tertiary purified gas. The mixture of the secondary half-amine liquid and the tertiary purified gas exits from the outlet of the tertiary absorber 04 and enters the gas-liquid separator 05 for gas-liquid separation. The tertiary purified gas exits from the purified gas outlet 051 on the gas-liquid separator 05 and is then output from the device.

[0084] The first outlet 036 and the second outlet 052 of the secondary halfamine liquid are connected to the inlet 012 of the primary amine liquid. The secondary halfamine liquids discharged from the first outlet 036 and the second outlet 052 are combined to form the primary amine liquid and input into the inlet 012 of the primary amine liquid.

[0085] The apparatus and method for recovering hydrogen sulfide from acidic gas provided in this application embodiment highly couples the primary absorber 01, the secondary absorber 03, and the tertiary absorber 04, and absorbs hydrogen sulfide with primary and secondary amine solutions containing amines. This enables cascaded, highly selective absorption of hydrogen sulfide from the acidic gas under very short reaction times. The recovered hydrogen sulfide product has high purity, and the secondary semi-lean amine solution can be combined into a primary amine solution for reuse, resulting in high amine utilization and low utility consumption.

[0086] In some embodiments of this application, the tertiary absorber 04 is further connected to an exogenous amine solution inlet pipe 042, wherein the exogenous amine solution is a solution containing an amine substance. The amine substance is preferably MDEA.

[0087] In some embodiments of this application, the purified gas outlet 051 is connected to a purified gas outlet pipe 053, and a first hydrogen sulfide content analyzer 131 is provided on the purified gas outlet pipe 053; a first regulating valve 132 is provided on the exogenous amine liquid inlet pipe 042, and the first hydrogen sulfide content analyzer 131 and the first regulating valve 132 are connected and controlled by pneumatic or electric signals.

[0088] The hydrogen sulfide content in the tertiary purified gas is monitored by the first hydrogen sulfide content analyzer 131 and controlled by the first regulating valve 132. When the first hydrogen sulfide content analyzer 131 detects that the hydrogen sulfide content in the purified gas is too high, it automatically opens the first regulating valve 132 to increase the flow rate of the exogenous amine liquid from outside the device to the tertiary absorber 04, thereby increasing the absorption of hydrogen sulfide in the secondary purified gas and ensuring that the hydrogen sulfide content in the tertiary purified gas meets the index requirements.

[0089] In some embodiments of this application, the absorption section is provided with mass transfer internals, which are packing materials or trays, and the packing materials are random packing or structured packing; let 1≤i≤m, the number of mass transfer units on the mass transfer internals in the i-th absorption section distributed from bottom to top is N. i Among them are:

[0090] N i =ln(C ii / C io )

[0091] C ii C represents the molar fraction of hydrogen sulfide in the primary purified gas entering the i-th absorption section. io The mass fraction of hydrogen sulfide in the primary purified gas leaving the i-th absorption section.

[0092] In some embodiments of this application, C ii and C io Calculated as follows:

[0093]

[0094] C ii =C i / k (i-1)

[0095] c io =C i / k i

[0096] Among them, C i C represents the molar fraction of hydrogen sulfide in the primary purified gas entering the gas-liquid separation section 031 from the primary absorber 01. o The amount of hydrogen sulfide in the secondary purified gas entering the tertiary absorber from the upper end of the secondary absorber.

[0097] Please refer to some embodiments of this application. Figure 2 , Figure 3 The absorption section is divided into a gas chamber 16 and a liquid chamber 17 by a partition plate, wherein the liquid chamber 17 is located above the gas chamber 16; a liquid collection trough 171 is formed by a recess on one side of the liquid chamber 17, and the first outlet 036 of the secondary halfamine liquid is located on the side of the liquid collection trough 171; a riser pipe 18 communicating with the gas chamber 16 is vertically arranged on the partition plate, and a rain cap 181 is provided at the upper end of the riser pipe to prevent liquid from entering the riser pipe 18.

[0098] The upper part of the absorption section is also provided with a nozzle that communicates with the first inlet 035 of the secondary amine liquid.

[0099] Secondary amine liquid enters the nozzle from the first inlet 035 and is sprayed downwards in the liquid chamber 17. Primary purified gas moves upwards from the gas chamber 16 and enters the liquid chamber 17 from the riser pipe 18, moving in the opposite direction to the downward spraying secondary amine liquid. Hydrogen sulfide is selectively absorbed. Since the collection tank 171 is recessed in the liquid chamber 17, the secondary half amine liquid formed by the absorption of hydrogen sulfide by the secondary amine liquid accumulates in the collection tank 171 and is discharged from the first outlet 036 of the secondary half amine liquid.

[0100] Preferably, in order to obtain good gas distribution, the riser pipes 18 should be evenly arranged on the cross-section of the liquid collection facility, and the area of ​​the riser pipes 18 is 15% to 45% of the cross-sectional area of ​​the absorption section.

[0101] The riser pipe 18 can be designed as a circular or rectangular structure, preferably a circular structure with a diameter of 50 to 150 mm;

[0102] The height of the riser pipe 18 is in the range of 100-600 mm to ensure that the residence time of the liquid above the partition plate is greater than or equal to 0.5 minutes;

[0103] To prevent liquid from flowing from the top of the riser pipe 18 and through the interior of the riser pipe 18 to the lower part of the absorption section, the top of the riser pipe 18 should be 150-250 mm higher than the highest liquid level on the partition plate.

[0104] Each riser pipe 18 is equipped with a rain cap 181 at the top to prevent liquid from entering the lower absorption section or gas-liquid flash evaporation section directly from the riser pipe 18 without liquid collection. The design requires that the gap area between the rain cap 181 and the top of the riser pipe 18 should be 1.15 to 1.25 times the cross-sectional area of ​​the riser pipe 18, and the periphery of the rain cap 181 should extend at least 25 mm beyond the riser pipe 18.

[0105] The minimum distance between the top of the rain cap 181 and the aforementioned mass transfer internals, i.e., the packing or tray, is 300-400 mm, so as to obtain good gas distribution in the upper packing or tray.

[0106] The collection tank 171 is a cuboid, and its length, width and height can be 1.5 to 4.0 times the diameter of the semi-lean liquid outlet.

[0107] In some embodiments of this application, the apparatus for recovering hydrogen sulfide from acidic gas further includes a flash evaporator 06, the primary sulfur-rich amine liquid outlet 037 is connected to the flash evaporator 06, the lower part of the flash evaporator 06 is provided with a secondary sulfur-rich amine liquid outlet 065, and the upper end of the flash evaporator 06 is provided with a flash vapor outlet 066.

[0108] The primary sulfur-rich amine solution is discharged from the primary sulfur-rich amine solution outlet 037 and introduced into the flash evaporator 06. Most of the carbon dioxide, light hydrocarbon components, and a small portion of hydrogen sulfide in the primary sulfur-rich amine solution are flashed out as flash vapor from the flash vapor outlet 066.

[0109] After most of the carbon dioxide and light hydrocarbon components are removed by flash evaporation, the remaining liquid phase components are output as secondary sulfur-rich amine liquid from the secondary sulfur-rich amine liquid outlet 065.

[0110] In some embodiments of this application, the flash evaporator 06 is provided with a secondary amine liquid third inlet 067 on its upper part.

[0111] The flash vapor contains hydrogen sulfide. To recover this hydrogen sulfide, a secondary amine solution is introduced to wash the flash vapor and recover this hydrogen sulfide.

[0112] In some embodiments of this application, the flash vapor outlet 066 is connected to a flash vapor outlet pipe 068 and a flash vapor circulation pipe 069, one end of the flash vapor circulation pipe 069 is connected to the flash vapor outlet 066, and the other end is connected to the flash evaporator 06.

[0113] Specifically, the purpose of setting up the flash vapor circulation pipe 069 is to improve the hydrogen sulfide absorption effect. A portion of the flash vapor is guided back into the flash evaporator 06 through the flash vapor circulation pipe 069 so that the secondary amine solution can further rinsing it. The flash vapor in the flash vapor circulation pipe 069 is referred to as the circulating gas. The larger the circulation volume of the circulating gas, the more hydrogen sulfide in the flash vapor is absorbed by the secondary amine solution, the lower the hydrogen sulfide content in the flash vapor output to the outside, and the higher the hydrogen sulfide recovery rate and purity (molar fraction) in the purified high-purity hydrogen sulfide gas. As needed, the mass flow rate ratio of the circulating gas to the flash vapor output to the outside can be 0 to 15.

[0114] In some embodiments of this application, a second regulating valve 142 is provided at the third inlet 067 of the secondary amine liquid, a third regulating valve 143 is provided on the flash vapor circulation pipe 069, and a second hydrogen sulfide content analyzer 141 is provided on the flash vapor outlet pipe 068. The second hydrogen sulfide content analyzer 141 is connected and controlled by the second regulating valve 142 and the third regulating valve 143 via pneumatic or electric signals.

[0115] The second hydrogen sulfide content analyzer 141 is used to monitor the hydrogen sulfide content of the flash vapor in the flash vapor outlet pipe 068. When the hydrogen sulfide content in the flash vapor output to the outside is high, the opening of the second regulating valve 142 and the third regulating valve 143 are increased to increase the rinsing amount of the secondary amine liquid on the flash vapor and the flow rate of the circulating gas, so that more hydrogen sulfide in the flash vapor can be absorbed. The quality indicators of the flash vapor output to the outside can meet the requirements of specific target values ​​or emission standards. For example, after the flash vapor output to the outside is incinerated (i.e., hydrogen sulfide is burned to generate SO2), the emission indicators meet the "Emission Standard of Pollutants for Petroleum Refining Industry" (GB31570-2015) which requires SO2 content in the flue gas to be ≤400mg / Nm³. 3 Requirements, or meeting the special emission limit of SO2 content ≤100mg / Nm 3 Requirements.

[0116] In some embodiments of this application, the flash evaporator 06 includes a flash evaporator 061, and a first flash section 062, a second flash section 063, and a circulating water cooler 064 arranged sequentially from bottom to top inside the flash evaporator 06, above the flash evaporator 061; the operating pressure at the top of the flash evaporator 06 is set to 50-450 kPa, the operating temperature at the top is set to 40-50°C, the operating temperature at the flash evaporator 061 is set to 60-80°C, and the residence time of the primary thiamine-rich liquid in the flash evaporator 061 is set to 15-45 minutes. The primary sulfur-rich amine solution enters the flash evaporator 06 from above the flash kettle 061 and below the first flash section 062. Most of the carbon dioxide, light hydrocarbon components, and a small portion of hydrogen sulfide in the primary sulfur-rich amine solution are flashed away as flash vapor. Since the flash vapor contains hydrogen sulfide, to recover this hydrogen sulfide, the secondary amine solution is sent above the second flash section 063 and below the circulating water cooler 064; that is, the third inlet 067 of the secondary amine solution is located above the second flash section 063 and below the circulating water cooler 064. The secondary amine solution comes into countercurrent contact with the rising flash vapor in the first flash section 062 and the second flash section 063, selectively absorbing the hydrogen sulfide in the flash vapor. The flash vapor, after selectively absorbing hydrogen sulfide, re-enters the circulating water cooler 064. The circulating water cooler 064 condenses the amine gas and water vapor carried by the flash vapor into liquid amine. Then, the flash vapor flows out from the top of the circulating water cooler 064, exits the flash evaporator 06 through the flash vapor outlet 066, and flows out from the bottom of the circulating water cooler 064, serving as the return amine liquid to the flash evaporator 06. This reflux flows downwards from the flash evaporator 06 and further absorbs hydrogen sulfide from the rising flash vapor. A portion of the flash vapor leaving the flash evaporator 06 is separated as recirculating gas. Specifically, a flash vapor circulation pipe 069 is installed; the other end of the flash vapor circulation pipe 069 is connected to the flash evaporator 06 at a position between the upper part of the first flash section 062 and the lower part of the second flash section 063. The circulating gas and the secondary amine liquid are in countercurrent contact in the second flash section 063. The hydrogen sulfide contained in the circulating gas is selectively absorbed by the secondary amine liquid, thereby further reducing the hydrogen sulfide content in the flash vapor. A gas compressor 12 is also installed on the flash vapor circulation pipe 069. Under the action of the gas compressor 12, the flash vapor is input from the flash vapor circulation pipe 069 to the flash evaporator 06.

[0117] In some embodiments of this application, both the first flash section 062 and the second flash section 063 are provided with random packing. The random packing is used to provide a contact surface for mass and heat transfer in gas-liquid countercurrent contact.

[0118] In some embodiments of this application, the random packing in the first flash section 062 and the second flash section 063 forms a packing layer with a height of 2 to 5 m.

[0119] In some embodiments of this application, the acidic gas load of the secondary amine liquid in the flash evaporator 06 is in the range of 0.20 to 0.50, or the gas-liquid ratio of the first flash section 062 in the flash evaporator 06 is 10 to 2000.

[0120] In some embodiments of this application, the apparatus for recovering hydrogen sulfide from acidic gas further includes a regeneration tower 08, and the secondary sulfur-rich amine liquid outlet 065 is connected to the regeneration tower 08.

[0121] The lower part of the regeneration tower 08 is connected to a reboiler 081 for heating the liquid flow inside the regeneration tower 08, the upper part of the regeneration tower 08 is provided with a first hydrogen sulfide outlet 085, and the bottom of the regeneration tower 08 is provided with a regenerated amine liquid outlet 086.

[0122] The function of regeneration tower 08 is to decompose and extract the acidic components from the secondary sulfur-rich amine solution. Under the separation action of regeneration tower 08, the acidic components, including hydrogen sulfide, in the amine-rich solution flow upwards and exit from the regeneration tower 08 through the first hydrogen sulfide outlet 085. Heavy components such as MDEA flow downwards, continuously releasing acidic components such as hydrogen sulfide during this downward flow, ultimately resulting in a regenerated amine solution with a very low hydrogen sulfide content at the bottom of the tower, which is exited through the regenerated amine solution outlet 086. Reboiler 081 provides the necessary heat for the separation of light and heavy components within regeneration tower 08.

[0123] In some embodiments of this application, the secondary thiamine-rich liquid outlet 065 is connected to the regeneration tower 08 via a first pumping device 07. The first pumping device 07 is a general device in the art capable of pumping liquids, such as a centrifugal pump. The first pumping device 07 is used to provide the power to allow the secondary thiamine-rich liquid to enter the regeneration tower 08.

[0124] In some embodiments of this application, the apparatus for recovering hydrogen sulfide from acidic gas further includes a condenser 082 and a reflux tank 083. The top of the regeneration tower 08 is connected to the condenser 082, the condenser 082 is connected to the reflux tank 083, and the reflux tank 083 is connected to the upper part of the regeneration tower 08. A second hydrogen sulfide outlet 087 is provided on the reflux tank 083.

[0125] The acidic components, including hydrogen sulfide, in the secondary sulfur-rich amine solution are output from the first hydrogen sulfide outlet 085 to the condenser 082. After being condensed and cooled by the condenser 082, the solution enters the reflux tank 083. In the reflux tank 083, gas and liquid phases are separated. The liquid phase is returned to the upper part of the regeneration tower 08 as reflux, and the gas phase is used as high-purity hydrogen sulfide gas to exit the device.

[0126] In some embodiments of this application, the reflux tank 083 is connected to the upper part of the regeneration tower 08 via a second pumping device 084. The liquid phase is pressurized by the second pumping device 084 and then refluxed back to the upper part of the regeneration tower 08. The second pumping device 084 is a general device in the art capable of pumping liquids, such as a centrifugal pump.

[0127] In some embodiments of this application, the reflux tank 083 is equipped with a dehydration device. After the aforementioned gas phase passes through the dehydration device to remove most of the moisture it carries, it is then discharged as high-purity hydrogen sulfide gas.

[0128] The regeneration tower 08 is preferably a plate tower, with a rectification section and a stripping section. The rectification section has 4 to 6 trays, and the stripping section has 16 to 26 trays. The top temperature is 105 to 115°C, the bottom temperature is 115 to 145°C, the top operating pressure is 150 to 250 kPa, and the reflux ratio is 0.5 to 5.0.

[0129] In some embodiments of this application, the apparatus for recovering hydrogen sulfide from acidic gas further includes a second cooler 10 and a filter 11, wherein the regenerated amine liquid outlet 086, the second cooler 10, and the filter 11 are sequentially connected; the filter 11 is connected to the secondary amine liquid first inlet 035, the secondary amine liquid second inlet 041, and the secondary amine liquid third inlet 067; the filter 11 is also provided with a secondary amine liquid discharge outlet 111;

[0130] The regenerated amine solution is cooled to 30-50°C by the lean solution second cooler 10 and then enters the filter 11. The filter 11 removes not only dissolved hydrocarbons and amine degradation products from the regenerated amine solution, but also destructive solid particles. The filter 11 is preferably an activated carbon filter 11, and is preferably operated in a one-on-one standby mode to filter out all amine degradation products, heat-stable salts, and other solid particles larger than or equal to 5 μm from the regenerated amine solution. The residence time of the regenerated amine solution in the activated carbon bed is not less than [a certain value]. The lifespan of the activated carbon bed in each activated carbon filter 11 is set to 6–12 months. Additionally, when treating cleaner acidic gas feedstocks with regenerated amine liquid, pitch-based spherical or granular activated carbon can be used, as the ratio of large, medium, and small pores within this activated carbon matches the particle size distribution of various soluble pollutants. Conversely, when treating dirtier acidic gas feedstocks, lignite-based spherical or granular activated carbon is selected, as this activated carbon contains a larger proportion of macropores, which can more effectively adsorb large molecular pollutants such as hydrocarbons and surfactants.

[0131] The filtered regenerated amine solution is used as a secondary amine solution and is input into the first inlet 035, the second inlet 041, and the third inlet 067 of the secondary amine solution.

[0132] Since the tertiary absorber 04 is also connected to the external amine liquid inlet pipe 042, the external amine liquid also serves to replenish the losses during the operation of the entire system and keep the amine liquid flow rate of the entire system constant. The secondary amine liquid discharge port 111 is used to discharge the amine degradation products, thermally stable salts and other residues generated during the operation of the entire device for recovering hydrogen sulfide from acidic gas.

[0133] In some embodiments of this application, the regenerated amine liquid outlet 086 is connected to the second cooler 10 via a third pumping device 09. The third pumping device 09 is a general device in the art capable of pumping liquids, such as a centrifugal pump. The third pumping device 09 is used to provide power for the regenerated amine liquid to flow from the regenerated amine liquid outlet 086 into the second cooler 10.

[0134] In some embodiments of this application, the regenerated amine liquid outlet 086 is connected to the second cooler 10 via a first pipe 154 and a second pipe 155 connected in parallel, wherein a portion of the first pipe 154 is disposed inside the bottom of the flash evaporator 06.

[0135] After the regenerated amine liquid is discharged from the regenerated amine liquid outlet 086, it is discharged through the first pipeline 154 and the second pipeline 155. The regenerated amine liquid in the first pipeline 154 first enters the flash evaporator 061, and the liquid phase in the flash evaporator 061 is heated by the indirect heat transfer method. Then it is mixed with the regenerated amine liquid in the second pipeline 155. After mixing, the temperature of the regenerated amine liquid is set to 75-115℃, and then it enters the second cooler 10.

[0136] In some embodiments of this application, a thermometer 151 for monitoring the internal temperature is provided at the bottom of the flash evaporator 06, a fourth regulating valve 152 is provided on the first pipeline 154, and a fifth regulating valve 153 is provided on the second pipeline 155. The thermometer 151 is connected to and controlled by the fourth regulating valve 152 and the fifth regulating valve 153 via pneumatic or electric signals.

[0137] Specifically, the thermometer 151 is used to monitor the temperature at the bottom of the flash evaporator 061. When the temperature at the bottom of the flash evaporator 061 is too high, the opening of the fourth regulating valve 152 is reduced and the opening of the fifth regulating valve 153 is increased, so that more of the regenerated amine liquid with higher temperature flows to the second pipeline 155, thereby reducing the temperature at the bottom of the flash evaporator 061. When the temperature at the bottom of the flash evaporator 061 is too low, the opening of the fourth regulating valve 152 is increased and the opening of the fifth regulating valve 153 is reduced, so that more of the regenerated amine liquid with higher temperature flows to the first pipeline 154, and exchanges more heat with the liquid at the bottom of the flash evaporator 061, thereby increasing the temperature at the bottom of the flash evaporator 061.

[0138] In some embodiments of this application, the second cooler 10 is also connected to a deoxygenated water inlet pipe 091.

[0139] Specifically, deoxygenated water from the outside is intermittently injected into the regenerated amine solution through the deoxygenated water inlet pipe 091 to compensate for the moisture carried away by hydrogen sulfide gas, purified gas, flash vapor products, etc., so as to keep the concentration of the MDEA solution circulating in the entire device stable.

[0140] Secondly, based on a general inventive concept, embodiments of this application also provide a method for recovering hydrogen sulfide from acidic gas, comprising the following steps:

[0141] S1: Provides acidic gas containing hydrogen sulfide and carbon dioxide;

[0142] S2: The acid gas is treated by the apparatus for recovering hydrogen sulfide from the acid gas described in the first aspect.

[0143] The specific implementation method of step S2 can be referred to the embodiments provided in the first aspect. The first aspect has given the specific working principle and working conditions of the device for recovering hydrogen sulfide in acidic gas described in this application. Those skilled in the art can implement step S2 according to the content of the first aspect.

[0144] In some embodiments of this application, the primary amine solution, secondary amine solution, and secondary half-amine solution are all solutions containing MDEA.

[0145] In some embodiments of this application, the amine solution may be a MDEA (N-methyldiethanolamine) solution with a mass fraction of 25% to 50%, or it may be a composite MDEA solution with a small amount of additives such as antifoaming agents, corrosion inhibitors, antioxidants, activators, etc. added to further improve the solvent performance.

[0146] In some embodiments of this application, the acidic gas load of the secondary amine solution in the absorption section is 0.25–0.55, or,

[0147] The primary purified gas introduced into the absorption section and the secondary amine liquid introduced into the absorption section have a gas-liquid ratio of 10 to 1000.

[0148] Specifically, the acid gas load refers to the number of moles of hydrogen sulfide and carbon dioxide removed from the acid gas by 1 mol of pure amine in the secondary amine solution, expressed as mol(H2S+CO2) / mol pure amine.

[0149] Specifically, the gas-liquid ratio refers to 1m 3 The volume of acidic gas treated by the secondary amine solution, expressed in m 3 acidic gas / m 3 Amine liquid representation;

[0150] Furthermore, for the absorption section, acidic gas refers to primary purified gas. The absorption section is any one of m absorption sections.

[0151] The acid gas load and gas-liquid ratio directly affect the purity of hydrogen sulfide in the obtained hydrogen sulfide product, the gas purification level, and the energy consumption of the apparatus. Increasing the acid gas load or gas-liquid ratio reduces the gas-liquid contact time, thus decreasing the amine solution's carbon dioxide absorption rate and increasing its selective absorption of hydrogen sulfide. Furthermore, increasing the acid gas load or gas-liquid ratio also reduces the amine solution's circulation volume, thereby lowering the apparatus's energy consumption and operating costs. Based on these two reasons, the acid gas load or gas-liquid ratio should be increased as much as possible while ensuring the purified gas quality meets standards. However, excessively high acid gas loads or gas-liquid ratios can lead to a rapid increase in hydrogen sulfide content in the purified gas, significantly worsening the purification level. Therefore, this application comprehensively considers factors such as raw material properties, amine solution selectivity, gas purification level, and apparatus energy consumption to select a suitable acid gas load or gas-liquid ratio.

[0152] In some embodiments of this application, the acidic gas load of the secondary amine solution in the tertiary absorber 04 is 0.20–0.40, or,

[0153] The gas-liquid ratio of the three-stage absorber 04 is 10 to 2000;

[0154] For the three-stage absorber 04, acidic gas refers to the gas purified in the second stage.

[0155] In some embodiments of this application, the apparent linear velocity of the fluid in the three-stage absorber 04 is 5 to 10.0 m / s.

[0156] In some embodiments of this application, the acidic gas load of the secondary amine liquid in flash evaporator 06 is in the range of 0.20 to 0.50, or...

[0157] The gas-liquid ratio of the first flash section 062 in the flash evaporator 06 is 10 to 2000;

[0158] For the flash evaporator 06, the acidic gas refers to the flash vapor in the first flash section 062.

[0159] The apparatus and method for recovering hydrogen sulfide from acidic gas provided in this application embodiment highly couples equipment such as a primary absorber 01, a secondary absorber 03, a tertiary absorber 04, a flash evaporator 06, and a regeneration tower 08. Hydrogen sulfide is absorbed by primary and secondary amine solutions containing amines. This enables cascaded, highly selective absorption of hydrogen sulfide from the acidic gas under short reaction times. The primary sulfur-rich amine solution, after absorbing hydrogen sulfide, enters the flash evaporator 06, which has a high operating temperature and low operating pressure. The regenerated amine... The high-temperature heat of the liquid causes more volatile components such as carbon dioxide and light hydrocarbons to flash away from the primary sulfur-rich amine liquid in the flash evaporator 061. A flash vapor circulation pipe 069 is installed to guide part of the flash vapor back to the flash evaporator 06 as circulating gas. The hydrogen sulfide contained in the circulating gas is selectively absorbed by the secondary amine liquid, thereby further reducing the hydrogen sulfide content in the flash vapor. After the above measures are implemented, the recovered hydrogen sulfide product has high hydrogen sulfide purity and high hydrogen sulfide recovery rate. Moreover, the secondary semi-lean amine liquid can be combined into the primary amine liquid for reuse, improving the utilization rate of amine. In summary, the apparatus and method for recovering hydrogen sulfide from acidic gas provided in this application have the characteristics of low utility consumption, low energy consumption, low equipment cost, and small footprint.

[0160] The following are specific embodiments based on the above content to further illustrate this application. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0161] Example 1

[0162] A chemical plant produces an acidic gas at a temperature of 40℃, a pressure of 1.7MPa, and a flow rate of 100kmol / h. The mole fraction of the substance is shown in Table 1.

[0163] Table 1. Composition of acidic gas feedstock produced by a chemical plant

[0164]

[0165] The amine solution from the outside (external amine solution) is a composite MDEA solution with a temperature of 40℃, a pressure of 1.2MPa, and a mass fraction of 30%.

[0166] The chemical plant plans to use the aforementioned amine solution to purify the hydrogen sulfide in the aforementioned acidic gas raw material. The purified hydrogen sulfide product is required to have a hydrogen sulfide molar fraction of not less than 98.5%, which will be used to produce high-quality sodium hydrosulfide products.

[0167] This embodiment is based on the apparatus for recovering hydrogen sulfide from acidic gas disclosed above, and Figures 1-3The implementation details are as follows: The primary absorber 01 uses an ejector with a converging single nozzle of conical shape and a cone angle of 7°. The ratio of the throat length to the throat diameter in the mixing chamber is 7.6. The acidic gas introduced through the acidic gas inlet 011 has a temperature of 40°C, a pressure of 1.7 MPa, and a flow rate of 100 kmol / h. The primary amine liquid introduced through the primary amine liquid inlet 012 has a temperature of 44.2°C, a pressure of 0.86 MPa, and a flow rate of 92.00 t / h. The gas-liquid two-phase contact time within the primary absorber 01 is 0.05 seconds, and 56.0% of the hydrogen sulfide in the acidic gas feedstock is selectively absorbed by the primary lean amine liquid. The outlet medium of the primary absorber 01 is a mixture of primary amine liquid and primary purified gas, with a temperature of 45.0°C and a pressure of 1.02 MPa.

[0168] The operating temperature at the outlet of the first cooler 02 is 40°C, and the operating pressure is 1.0 MPa;

[0169] In the secondary absorber 03, the gas-liquid separation section 031 operates at a temperature of 40°C and a pressure of 1.0 MPa. The primary purified gas has three absorption sections. The pressure drop generated by the upward flow of the first absorption section 032, the second absorption section 033, and the third absorption section 034 is 0.03 MPa. The secondary amine liquid has a flow rate of 28.50 t / h at the first inlet 035 of each absorption section. The temperatures of the secondary half-amine liquid discharged from the first outlet 036 of the first absorption section 032, the second absorption section 033, and the third absorption section 034 are 42.7°C, 45.2°C, and 47.3°C, respectively. 90.0% of the hydrogen sulfide contained in the primary purified gas is removed in the secondary absorber 03.

[0170] The tertiary absorber 04 is used to remove hydrogen sulfide from the secondary purified gas, reducing the hydrogen sulfide molar fraction of the obtained tertiary purified gas to 0.000224, which meets the specific requirements of the chemical plant. In the tertiary absorber 04, the flow rate of the secondary amine liquid introduced from the second inlet 041 is 4.30 t / h, and the average flow rate of the external amine liquid introduced from the external amine liquid inlet pipe 042 is 50 kg / h. The outlet temperature of the tertiary absorber 04 is 49.5℃, and the outlet pressure is 0.88 MPa. The tertiary absorber 04 uses an SX-type static mixer, and the gas-liquid two-phase contact time is 0.25 seconds.

[0171] The operating temperature at the purified gas outlet 051 of the gas-liquid separator 05 is 49.5℃ and the operating pressure is 0.86MPa.

[0172] The top operating pressure and operating temperature of the flash evaporator 06 are set to 100 kPa and 45°C, respectively; the operating temperature of the flash evaporator 061 is set to 70°C; and the residence time of the primary sulfur-rich amine solution in the flash evaporator 061 is set to 30 minutes. The random packing material used for gas-liquid countercurrent contact in the first flash section 062 and the second flash section 063 is Pall ring packing with a diameter of 38 mm, and the packing layer height is 3 m in both sections. The flow rate of the secondary amine solution introduced from the third inlet 067 is 2.50 t / h.

[0173] The outlet operating pressure of the gas compressor 12 is 200 kPa, and the mass flow rate ratio of the circulating gas to the flash vapor output to the outside is 1.5.

[0174] The first pumping device 07 is a centrifugal pump with an outlet operating pressure of 450 kPa;

[0175] The regeneration tower 08 is a plate tower, with 4 trays in the rectification section and 20 trays in the stripping section; the top operating temperature is 109℃, the bottom operating temperature is 125℃, the top operating pressure is 170kPa, and the reflux ratio is 3.0.

[0176] The third pumping device 09 is a centrifugal pump with an operating pressure of 1.6 MPa at the outlet.

[0177] The operating temperature at the outlet of the second cooler 10 is 40°C, and the operating pressure is 1.4 MPa.

[0178] The filter 11 is an activated carbon filter 11, with one on and one on standby, used to filter out all amine degradation products or solid particles ≥5μm in the regenerated amine solution. The activated carbon is lignite-based granular activated carbon, and the residence time of the amine solution in the activated carbon bed is 25 minutes. The average flow rate of the residue output to the outside is 6kg / h.

[0179] After the above operations, the mass flow rate, mass flow rate, and mass fraction of the materials entering and exiting each device are shown in Table 2.

[0180] Table 2. Mass flow rate, mass flow rate, and mass fraction of materials at each inlet and outlet device.

[0181]

[0182]

[0183] As shown in Table 2, by using the apparatus and method disclosed in this application to purify hydrogen sulfide in acidic gas, the molar fraction of hydrogen sulfide in the hydrogen sulfide product is increased from 68.6% to over 98.6%. The purified hydrogen sulfide product can meet the requirements of actual production and can be used to produce high-quality sodium hydrosulfide products.

[0184] Example 2

[0185] This embodiment is based on the apparatus for recovering hydrogen sulfide from acidic gas disclosed above, and Figures 1-3 The content implementation. The amount of hydrogen sulfide C in the primary purified gas entering the secondary absorber 03. i =64%, the molar fraction of hydrogen sulfide in the secondary purified gas leaving the secondary absorber 03 from the top. o =8%, the number of absorption stages of the secondary absorber 03 is m=3, then the calculated coefficient k is:

[0186]

[0187] The molar fraction of hydrogen sulfide in the primary purified gas entering the first absorption section 032:

[0188] C1 i＝ C i / k (1-1) =0.64 / 2 (1-1) =0.64

[0189] The molar fraction of hydrogen sulfide in the primary purified gas leaving the first absorption section 032:

[0190] C io =C i / k i =0.64 / 2 1 =0.32

[0191] Number of mass transfer units (theoretical plates) in the first absorption section 032:

[0192] N1=ln(C 1i / C 1o = ln(0.64 / 0.32) = 0.6931

[0193] Using the same method, the number of mass transfer units (theoretical plates) for the second absorption section 033 and the third absorption section 034 can be calculated to be 0.6931.

[0194] The first absorption section 032, the second absorption section 033, and the third absorption section 034 all use Φ38mm random packing. The height of the packing layer corresponding to one mass transfer unit of the random packing layer is 1000mm. Therefore, the height of the packing layer in the first absorption section 032, the second absorption section 033, and the third absorption section 034 is 693.1mm.

[0195] Example 3

[0196] This embodiment is based on the apparatus for recovering hydrogen sulfide from acidic gas disclosed above, and Figures 1-3The content was implemented as described in Example 1, and the operating conditions were the same. To improve the absorption of hydrogen sulfide, the mass flow rate ratio of the circulating gas to the flash vapor product was increased from 1.5 in Example 1 to 10.0, thereby increasing the molar fraction of hydrogen sulfide in the purified hydrogen sulfide gas from 98.6835% in Example 1 to 99.1227%.

[0197] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is indicated in this specification, it means including any referenced number (fraction or integer) within the indicated range.

[0198] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this specification, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this specification, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone. For relationships between three or more related objects described using "and / or," it means that any one of these three related objects can exist alone, or at least two of them can exist simultaneously. For example, A, and / or B, and / or C can mean that any one of A, B, and C exists alone, or any two of them exist simultaneously, or all three of them exist simultaneously. In this specification, "at least one" means one or more, and "more" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0199] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown in this specification, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An apparatus for recovering hydrogen sulfide from acidic gas, characterized in that, The apparatus for recovering hydrogen sulfide from acidic gas includes: A primary absorber, wherein the primary absorber is provided with an acid gas inlet and a primary amine liquid inlet; A secondary absorber includes a gas-liquid separation section and m absorption sections distributed from bottom to top inside the secondary absorber, wherein m is not less than 1. The gas-liquid separation section is connected to the primary absorber. The upper end of the absorption section is provided with a first inlet of secondary amine liquid and the lower end is provided with a first outlet of secondary half amine liquid. The lower end of the gas-liquid separation section is provided with an outlet of primary sulfur-rich amine liquid. A tertiary absorber is connected to the upper end of the secondary absorber, and a second inlet for secondary amine liquid is provided on the tertiary absorber; A gas-liquid separator, wherein the three-stage absorber is connected to the gas-liquid separator, and the gas-liquid separator is provided with a purified gas outlet and a second outlet for the secondary half amine liquid; The first outlet and the second outlet of the secondary halfamine liquid are connected to the inlet of the primary amine liquid. The secondary halfamine liquids discharged from the first outlet and the second outlet of the secondary halfamine liquid are combined into the primary amine liquid and input into the inlet of the primary amine liquid. The primary amine solution, secondary amine solution, and secondary half-amine solution are all solutions containing MDEA.

2. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 1, characterized in that, The three-stage absorber is also connected to an exogenous amine solution inlet tube, wherein the exogenous amine solution is a solution containing MDEA.

3. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 2, characterized in that, The purified gas outlet is connected to a purified gas outlet pipe, and a first hydrogen sulfide content analyzer is installed on the purified gas outlet pipe; a first regulating valve is installed on the exogenous amine liquid inlet pipe, and the first hydrogen sulfide content analyzer and the first regulating valve are connected and controlled by pneumatic or electric signals.

4. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 1, characterized in that, The absorption section is equipped with mass transfer internals; let 1≤i≤m, the number of mass transfer units on the mass transfer internals in the i-th absorption section distributed from bottom to top is N. i Among them are: C ii C is the molar fraction of hydrogen sulfide in the acid gas feed of the i-th absorption section; io The amount fraction of hydrogen sulfide in the acidic gas output of the i-th absorption section.

5. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 4, characterized in that, C ii and C io Calculated as follows: Among them, C i C represents the molar fraction of hydrogen sulfide in the acidic gas entering the gas-liquid separation section from the primary absorber. o The amount of hydrogen sulfide in the acidic gas entering the tertiary absorber from the upper end of the secondary absorber.

6. The apparatus for recovering hydrogen sulfide from acidic gas according to any one of claims 1-5, characterized in that, The device for recovering hydrogen sulfide from acidic gas also includes a flash evaporator. The primary sulfur-rich amine liquid outlet is connected to the flash evaporator. The lower part of the flash evaporator is provided with a secondary sulfur-rich amine liquid outlet, and the upper part of the flash evaporator is provided with a flash vapor outlet.

7. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 6, characterized in that, The flash evaporator is equipped with a third inlet for secondary amine liquid at its upper part.

8. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 7, characterized in that, The flash vapor outlet is connected to a flash vapor outlet pipe and a flash vapor circulation pipe. One end of the flash vapor circulation pipe is connected to the flash vapor outlet, and the other end is connected to the flash evaporator.

9. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 8, characterized in that, A second regulating valve is provided at the third inlet of the secondary amine liquid, a third regulating valve is provided on the flash vapor circulation pipe, and a second hydrogen sulfide content analyzer is provided on the flash vapor outlet pipe. The second hydrogen sulfide content analyzer communicates and controls the second and third regulating valves via pneumatic or electric signals.

10. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 7, characterized in that, The apparatus for recovering hydrogen sulfide from acidic gas also includes a regeneration tower, and the outlet of the secondary sulfur-rich amine liquid is connected to the regeneration tower; The lower part of the regeneration tower is connected to a reboiler for heating the liquid flow inside the regeneration tower, the upper part of the regeneration tower is provided with a first hydrogen sulfide outlet, and the bottom of the regeneration tower is provided with a regenerated amine liquid outlet.

11. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 10, characterized in that, The apparatus for recovering hydrogen sulfide from acidic gas further includes a condenser and a reflux tank. The top of the regeneration tower is connected to the condenser, the condenser is connected to the reflux tank, and the reflux tank is connected to the upper part of the regeneration tower. A second hydrogen sulfide outlet is provided on the reflux tank.

12. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 10, characterized in that, The apparatus for recovering hydrogen sulfide from acidic gas further includes a second cooler and a filter. The regenerated amine liquid outlet, the second cooler, and the filter are connected in sequence. The filter is connected to the second secondary amine liquid inlet, the second secondary amine liquid inlet, and the third secondary amine liquid inlet. The filter is also provided with a secondary amine liquid discharge outlet.

13. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 12, characterized in that, The regenerated amine liquid outlet is connected to the second cooler through a first pipe and a second pipe connected in parallel, wherein a portion of the first pipe is located inside the bottom of the flash evaporator.

14. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 13, characterized in that, The bottom of the flash evaporator is equipped with a thermometer to monitor its internal temperature. A fourth regulating valve is installed on the first pipeline, and a fifth regulating valve is installed on the second pipeline. The thermometer communicates and controls the fourth and fifth regulating valves via pneumatic or electric signals.

15. The apparatus for recovering hydrogen sulfide from acidic gas according to claim 12, characterized in that, The second cooler is also connected to a deoxygenated water inlet pipe.

16. A method for recovering hydrogen sulfide from acidic gas, characterized in that, The method for recovering hydrogen sulfide from acidic gas includes the following steps: Provides acidic gas containing hydrogen sulfide and carbon dioxide; The acid gas is treated by the apparatus for recovering hydrogen sulfide from the acid gas according to any one of claims 6-15.

17. The method for recovering hydrogen sulfide from acidic gas according to claim 16, characterized in that, The acidic gas load of the secondary amine solution in the absorption section is 0.25~0.55, or... The gas-liquid ratio of the primary purified gas introduced into the absorption section to the secondary amine liquid introduced into the absorption section is 10~1000.

18. The method for recovering hydrogen sulfide from acidic gas according to claim 16, characterized in that, The acidic gas load of the secondary amine liquid in the flash evaporator is 0.20~0.50.

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