A flue gas decarbonization system and process for natural gas purification

Abstract

This invention discloses a flue gas decarbonization system and process for natural gas purification, including a natural gas desulfurization unit, a sulfur recovery unit, a tail gas treatment unit, and an acid gas enrichment unit. The tail gas treatment unit includes a tail gas hydrogenation reactor, a tail gas absorption tower, and a tail gas regeneration tower. The acid gas enrichment unit includes an acid gas absorption tower and an acid gas regeneration tower. The tail gas absorption tower uses a fully desulfurized solvent to remove carbon dioxide and a small amount of sulfides from the tail gas, and then regenerates it with a rich solution to obtain a high carbon-to-sulfur ratio acid gas stream. The acid gas absorption tower uses a selective desulfurization solvent to remove hydrogen sulfide from the high carbon-to-sulfur ratio acid gas to obtain a high-concentration carbon dioxide stream. This invention utilizes the existing tail gas treatment unit, modifies the absorption tower, uses a fully desulfurized solvent to remove sulfur and recover carbon dioxide and a small amount of hydrogen sulfide from the tail gas, regenerates it to obtain a small flow rate of high carbon-to-sulfur ratio acid gas, and then uses an acid gas enrichment device to selectively absorb the acid gas to obtain a high-concentration carbon dioxide stream, thus completing the decarbonization treatment and efficient carbon capture.

Description

Technical Field

[0001] This invention relates to the field of natural gas purification technology, and more specifically, to a flue gas decarbonization system and process for natural gas purification. Background Technology

[0002] The amine method is currently the mainstream technology for carbon capture in post-combustion flue gas. The decarbonization unit mainly consists of an absorption unit, a regeneration unit, and a heat exchange unit. The conventional process flow is as follows: After pretreatment for dust removal and cooling, the flue gas contacts the decarbonization solution in the absorption tower to remove CO2. After passing through a purified gas separator, it enters the exhaust chimney. The rich amine solution at the bottom of the decarbonization absorption tower is heated through heat exchange and then enters the regeneration tower to generate high-temperature desulfurization lean solution. The lean solution, after heat exchange and cooling, is recycled back to the decarbonization absorption tower. The acid gas obtained from the regeneration of the rich solution is cooled and sent to subsequent dehydration and compression units for CO2 storage and utilization.

[0003] For natural gas purification plants, flue gas is the exhaust gas after desulfurization, sulfur recovery, and tail gas treatment. Currently, flue gas from domestic natural gas purification plants is directly emitted after tail gas desulfurization without carbon capture. Current methods for decarbonizing flue gas after natural gas purification typically involve further removing and recovering residual sulfides in the tail gas treatment unit before it enters a decarbonization unit for further treatment. For natural gas purification plants with a capacity of 2 million cubic meters per day or more, the flue gas flow rate is large, ranging from 20,000 to 40,000 cubic meters per hour; its pressure is relatively low, close to atmospheric pressure. Therefore, to ensure a high CO2 removal rate, a high solution circulation rate is required, resulting in a large scale and investment in decarbonization units, leading to poor economic efficiency in carbon capture.

[0004] In view of the above, this application is hereby submitted. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a flue gas decarbonization system and process for natural gas purification. It improves the absorption process of the absorption tower in the existing natural gas tail gas treatment unit by employing a total desulfurization solvent to remove sulfur and recover most of the carbon dioxide and a small amount of hydrogen sulfide from the tail gas. This regenerates a small flow rate of high carbon-to-sulfur ratio acid gas. An additional acid gas enrichment unit then selectively absorbs the acid gas to obtain a high-concentration carbon dioxide stream. Compared to the traditional tail gas sulfur recovery + decarbonization device tail gas carbon capture method, this invention eliminates the need for a large-scale amine-based decarbonization unit. Only a small acid gas enrichment unit is required to meet the carbon capture needs of existing natural gas purification plants. The process is simple, requires a small footprint, and significantly reduces the construction investment for flue gas carbon capture.

[0006] This invention is achieved through the following technical solution:

[0007] A decarbonization system for natural gas purification includes a natural gas desulfurization unit, a sulfur recovery unit, a tail gas treatment unit, and an acid gas enrichment unit connected in sequence.

[0008] The natural gas desulfurization unit includes a natural gas absorption tower, a flash tower, a regeneration tower, a purified gas separator, an acid gas separator, a lean and rich liquid heat exchanger, a lean liquid cooler, an acid gas air cooler, and a lean liquid pump.

[0009] The sulfur recovery unit includes: a combustion furnace, a Claus reactor, and a sulfur condenser;

[0010] The exhaust gas treatment unit includes: an exhaust gas hydrogenation reactor, an exhaust gas quench tower, an exhaust gas absorption tower, an exhaust gas regeneration tower, a purified gas separator, an acid gas separator, a lean and rich liquid heat exchanger, a lean liquid cooler, an acid gas air cooler, a lean liquid pump, a rich liquid pump, and an exhaust gas incinerator.

[0011] The acid gas concentration unit includes: an acid gas absorption tower, an acid gas regeneration tower, a lean and rich liquid heat exchanger, a reboiler, an acid gas cooler, a lean liquid pump, and a rich liquid pump.

[0012] The natural gas desulfurization unit uses the amine process or its derivative process for desulfurization, and can adopt a multi-stage feeding and dual-tower absorption method.

[0013] The sulfur recovery unit adopts the conventional Claus process and its derivative processes, and uses a two-stage or three-stage Claus reactor.

[0014] The exhaust gas treatment unit adopts a combination of SCOT hydrogenation reduction absorption process or its derivative process and alkanolamine process or its derivative process to remove carbon dioxide and a small amount of sulfides from the exhaust gas, as well as rich liquid regeneration of high carbon-to-sulfur ratio acid gas flow. The exhaust gas treatment unit also adopts multi-stage feeding and dual-tower absorption.

[0015] The acid gas enrichment unit uses the alkanolamine process or its derivative process to remove hydrogen sulfide from the acid gas stream with a high carbon-to-sulfur ratio, and obtains a high-concentration carbon dioxide gas stream. The acid gas enrichment unit can adopt multi-stage feeding and dual-tower absorption.

[0016] The gas outlet pipeline of the final stage Claus reactor of the sulfur recovery unit is connected to the inlet pipeline of the tail gas hydrogenation reactor of the tail gas treatment unit.

[0017] The acid gas outlet pipeline of the tail gas regeneration tower of the tail gas treatment unit is connected to the gas inlet pipeline of the acid gas absorption tower in the acid gas concentration unit.

[0018] The gas outlet pipeline of the acid gas regeneration tower of the acid gas enrichment unit is connected to the inlet pipeline of the combustion furnace of the sulfur recovery unit.

[0019] The present invention also provides a decarbonization process for natural gas purification, the specific steps of which are as follows:

[0020] 1) Natural gas is introduced from the bottom of the natural gas absorption tower and comes into countercurrent contact with the desulfurization lean liquid entering from the top of the natural gas absorption tower. After the gas exits the tower, it is dehydrated and then transported into the product natural gas pipeline. The rich liquid at the bottom of the natural gas absorption tower enters the top of the regeneration tower after passing through the flash tower and the lean-rich liquid heat exchanger. The high-temperature lean liquid at the bottom of the regeneration tower is cooled by the lean-rich liquid heat exchanger and the lean liquid cooler and then pumped into the top of the absorption tower for recycling. The acid gas generated by the regeneration tower enters the combustion furnace of the sulfur recovery unit after passing through the acid gas cooler and the acid gas separator.

[0021] 2) The acid gas from the acid gas separator of the natural gas desulfurization unit enters the combustion furnace and undergoes the Claus reaction. Then it enters the Claus reactor for further reaction, converting more than 99% of the hydrogen sulfide in the acid gas into sulfur, obtaining high-temperature liquid sulfur. After cooling in the sulfur condenser, industrial sulfur products are obtained. The remaining tail gas mainly contains nitrogen, carbon dioxide and a small amount of sulfides.

[0022] 3) The tail gas from the Claus reactor in the sulfur recovery unit enters the tail gas hydrogenation reactor, where all the sulfides in the tail gas are converted into hydrogen sulfide. After being cooled, the tail gas enters the tail gas quench tower and then enters the bottom of the tail gas absorption tower to countercurrently contact the lean liquid entering from the top of the tail gas absorption tower. The gas exiting the tower is mainly nitrogen with a small amount of carbon dioxide and trace amounts of hydrogen sulfide. It then enters the tail gas incinerator for combustion and emission. The rich liquid at the bottom of the absorption tower is pumped into the lean-rich liquid heat exchanger by the rich liquid pump and then enters the top of the tail gas regeneration tower. The high-temperature lean liquid at the bottom of the tail gas regeneration tower is cooled by the lean-rich liquid heat exchanger and the lean liquid cooler before entering the top of the tail gas absorption tower for recycling. The acid gas flow with a high carbon-to-sulfur ratio generated by the regeneration tower enters the acid gas enrichment unit after passing through the acid gas cooler and the acid gas separator.

[0023] 4) The regenerated high carbon-to-sulfur ratio acid gas stream from the tail gas treatment unit is cooled and then enters the bottom of the acid gas absorption tower to countercurrently contact the lean liquid entering from the top of the acid gas absorption tower. The gas exiting the tower becomes a high-concentration carbon dioxide stream, which enters the carbon dioxide pretreatment unit for dehydration and compression, completing decarbonization and carbon capture. The rich liquid at the bottom of the acid gas absorption tower is pumped into the lean-rich liquid heat exchanger by the rich liquid pump and then enters the top of the regeneration tower. The high-temperature lean liquid at the bottom of the regeneration tower is cooled by the lean-rich liquid heat exchanger and the lean liquid cooler and then enters the top of the acid gas absorption tower for recycling. The acid gas generated by the regeneration tower is returned to the inlet pipeline of the combustion furnace in the sulfur recovery unit after passing through the acid gas cooler and the acid gas separator for sulfur recovery.

[0024] The lean solution entering the tail gas absorption tower in the tail gas treatment unit is a complete removal solvent, including primary and secondary amine aqueous solutions containing at least one -NH2 or -NH- in molecules such as MEA (ethanolamine) and DEA (diethanolamine), as well as complete removal formulation solvent aqueous solutions; the lean solution entering the acid gas absorption tower in the acid gas concentration unit is a selective absorption solvent, including MDEA (methyldiethanolamine) or tertiary amines without hydrogen atoms on the amino group, hindered amines, and formulation solvent aqueous solutions with selective removal of hydrogen sulfide.

[0025] The decarbonization system and process of this invention modify or construct a new absorption tower in the existing tail gas treatment unit, transforming or constructing a plate tower with more than 20 trays. Simultaneously, the absorption process of the absorption tower is improved, employing a fully desulfurized solvent to remove most of the carbon dioxide and a small amount of hydrogen sulfide from the tail gas, regenerating a small flow rate of high carbon-to-sulfur ratio acid gas. An additional acid gas enrichment unit then selectively absorbs the acid gas to obtain a high-concentration carbon dioxide stream, completing decarbonization and carbon capture. Compared to the traditional tail gas sulfur recovery + decarbonization device tail gas carbon capture method, this method eliminates the need for a large-scale amine-based decarbonization unit. Only a small acid gas enrichment unit needs to be constructed and combined with the existing natural gas purification tail gas treatment unit to meet the carbon capture requirements of existing natural gas purification plants. The process is simple, requires a small footprint, and can significantly reduce the construction investment for flue gas carbon capture.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] 1. The present invention provides a flue gas decarbonization system and process for natural gas purification. By utilizing the original tail gas treatment unit, the absorption tower is modified and a total desulfurization solvent is used to remove sulfur and recover most of the carbon dioxide and a small amount of hydrogen sulfide in the tail gas. The gas is then regenerated to obtain a small flow rate of high carbon-to-sulfur ratio acid gas. The acid gas is then selectively absorbed by an acid gas enrichment device to obtain a high concentration of carbon dioxide gas flow, thus completing the decarbonization treatment and efficient carbon capture.

[0028] 2. The flue gas decarbonization system and process for natural gas purification provided in this embodiment of the invention does not require the construction of a large-scale amine decarbonization device. Only a small acid gas enrichment unit needs to be built and combined with the existing tail gas treatment unit of natural gas purification to meet the carbon capture of tail gas from the existing natural gas purification plant.

[0029] 3. The flue gas decarbonization system and process for natural gas purification provided in this embodiment of the invention have a small footprint and simple process, which can significantly reduce the investment in flue gas carbon capture construction. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a flow chart of the flue gas decarbonization process for natural gas purification provided in Embodiment 1 of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0033] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0034] Throughout this specification, references to “an embodiment,” “an example,” or “an example” mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases “an embodiment,” “an example,” “an example,” or “an example” appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0035] In the description of this invention, the terms "front," "rear," "left," "right," "upper," "lower," "vertical," "horizontal," "high," "low," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention.

[0036] Example 1

[0037] This invention provides a decarbonization process for natural gas purification, such as... Figure 1 As shown, the specific steps are as follows:

[0038] 1) Natural gas is introduced from the bottom of the natural gas absorption tower and comes into countercurrent contact with the desulfurization lean liquid entering from the top of the natural gas absorption tower. After the gas exits the tower, it is dehydrated and then transported into the product natural gas pipeline. The rich liquid at the bottom of the natural gas absorption tower enters the top of the regeneration tower after passing through the flash tower and the lean-rich liquid heat exchanger. The high-temperature lean liquid at the bottom of the regeneration tower is cooled by the lean-rich liquid heat exchanger and the lean liquid cooler and then pumped into the top of the absorption tower for recycling. The acid gas generated by the regeneration tower enters the combustion furnace of the sulfur recovery unit after passing through the acid gas cooler and the acid gas separator.

[0039] 2) The acid gas from the acid gas separator of the natural gas desulfurization unit enters the combustion furnace and undergoes the Claus reaction. Then it enters the Claus reactor for further reaction, converting more than 99% of the hydrogen sulfide in the acid gas into sulfur, obtaining high-temperature liquid sulfur. After cooling in the sulfur condenser, industrial sulfur products are obtained. The remaining tail gas mainly contains nitrogen, carbon dioxide and a small amount of sulfides.

[0040] 3) The tail gas from the Claus reactor in the sulfur recovery unit enters the tail gas hydrogenation reactor, where all the sulfides in the tail gas are converted into hydrogen sulfide. After being cooled, the tail gas enters the tail gas quench tower and then enters the bottom of the tail gas absorption tower to have countercurrent contact with the lean liquid (MEA 30%) entering from the top of the tail gas absorption tower. The gas exiting the tower is completely desulfurized and is mainly nitrogen with a small amount of carbon dioxide and trace amounts of hydrogen sulfide. It then enters the tail gas incinerator for combustion and emission. The rich liquid at the bottom of the absorption tower is pumped into the lean-rich liquid heat exchanger by the rich liquid pump and then enters the top of the tail gas regeneration tower. The high-temperature lean liquid at the bottom of the tail gas regeneration tower is cooled by the lean-rich liquid heat exchanger and the lean liquid cooler before entering the top of the tail gas absorption tower for recycling. The high carbon-to-sulfur ratio regenerated acid gas 1 generated by the regeneration tower enters the acid gas enrichment unit after passing through the acid gas cooler and the acid gas separator.

[0041] 4) Regenerated acid gas 1 with a high carbon-to-sulfur ratio from the tail gas treatment unit is cooled and then enters the bottom of the acid gas absorption tower to come into countercurrent contact with the lean liquid (45% MDEA) entering from the top of the acid gas absorption tower. The gas exiting the tower is concentrated into a high-concentration carbon dioxide gas stream, which enters the carbon dioxide pretreatment unit for dehydration and compression to complete decarbonization and carbon capture. The rich liquid at the bottom of the acid gas absorption tower is pumped into the lean-rich liquid heat exchanger by the rich liquid pump and then enters the top of the regeneration tower. The high-temperature lean liquid at the bottom of the regeneration tower is cooled by the lean-rich liquid heat exchanger and the lean liquid cooler and then enters the top of the acid gas absorption tower for recycling. The regenerated acid gas 2 generated by the regeneration tower is returned to the inlet pipeline of the combustion furnace in the sulfur recovery unit after passing through the acid gas cooler and the acid gas separator for sulfur recovery.

[0042] Example 2

[0043] The traditional SOCT desulfurization + tail gas carbon capture route for exhaust gas treatment devices is as follows:

[0044] 1) Natural gas desulfurization and sulfur recovery are carried out using the same process as in the example to obtain tail gas, which is then desulfurized using a tail gas treatment device SOCT to obtain desulfurized tail gas;

[0045] 2) The desulfurization tail gas is fed into the alcohol amine decarbonization unit. The gas exiting the tower is decarbonized tail gas, and after rich liquid regeneration, regenerated acid gas is obtained.

[0046] Using the process route of the present invention provided in Example 1 (steps 3 and 4 in Example 1) and the conventional route of this example, the tail gas with the same component content was subjected to desulfurization and decarbonization treatment. The main components of the tail gas before entering the hydrogenation reactor were H2S 2.22%, CO2 26.73%, and a flow rate of 12374 Nm³. 3 The specific parameters after entering the hydrogenation reactor and undergoing desulfurization and decarbonization are shown in Table 1 below.

[0047] Table 1 Gas parameter values ​​at each stage of exhaust gas treatment process

[0048]

[0049] Example 3

[0050] The traditional SOCT desulfurization + tail gas carbon capture route for exhaust gas treatment devices is as follows:

[0051] 1) Natural gas desulfurization and sulfur recovery are carried out using the same process as in the example to obtain tail gas, which is then desulfurized using a tail gas treatment device SOCT to obtain desulfurized tail gas;

[0052] 2) The desulfurization tail gas is fed into the alkanolamine decarbonization unit. The gas exiting the tower is decarbonization tail gas. The regenerated acid gas obtained after rich liquid regeneration is a high-concentration carbon dioxide gas stream.

[0053] Using the process route of the present invention provided in Example 1 (steps 3 and 4 in Example 1) and the conventional route of this example, the tail gas with the same component content was subjected to desulfurization and decarbonization treatment. The main components of the tail gas before entering the hydrogenation reactor were H2S 1.03%, CO2 32.23%, and a flow rate of 12403 Nm³. 3 The specific parameters after entering the hydrogenation reactor and undergoing desulfurization and decarbonization are shown in Table 1 below.

[0054] Table 2 Gas parameter values ​​at each stage of exhaust gas treatment process

[0055]

[0056]

[0057] As can be seen from the data in Tables 1 and 2, if the traditional SCOT desulfurization + amine decarbonization process is used, the decarbonization solution circulation rate needs to reach 100 m³ / s to obtain a high CO2 recovery rate. 3 For processes exceeding a certain flow rate (e.g., high flow rate), the energy consumption and investment of the equipment are very high. However, using the process route of this invention, only slight modifications are needed to the absorption tower in the SCOT process, replacing it with a fully decontamination solvent, and then concentrating the acid gas to indirectly obtain a small flow rate of high-concentration CO2. The solution circulation volume during concentration is only 30m³. 3 The amount of acid gas processed is only about 34% of the original decarbonization tail gas volume, which can greatly reduce the investment in equipment construction and operating costs.

[0058] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A flue gas decarbonization system for natural gas purification, characterized by, It includes a natural gas desulfurization unit, a sulfur recovery unit, a tail gas treatment unit, and an acid gas enrichment unit connected in sequence; The natural gas desulfurization unit includes a natural gas absorption tower, a flash evaporation tower, and a regeneration tower; The sulfur recovery unit includes a combustion furnace and a Claus reactor; The exhaust gas treatment unit includes an exhaust gas hydrogenation reactor, a quench tower, an exhaust gas absorption tower, an exhaust gas regeneration tower, and an exhaust gas incinerator. The acid gas concentration unit includes an acid gas absorption tower and an acid gas regeneration tower; In the tail gas treatment unit, the tail gas absorption tower uses a fully descaling solvent to remove carbon dioxide and a small amount of sulfides from the tail gas, and then it is passed into the tail gas regeneration tower rich liquid to regenerate and obtain a high carbon-to-sulfur ratio acid gas stream. In the acid gas enrichment unit, the acid gas absorption tower uses selective desulfurization solvent to remove hydrogen sulfide from the acid gas stream with a high carbon-to-sulfur ratio, and obtains a high-concentration carbon dioxide gas stream. The exhaust gas treatment unit also includes a purified gas separator, an acid gas separator, a lean and rich liquid heat exchanger, a lean liquid cooler, an acid gas air cooler, a lean liquid pump, and a rich liquid pump. The acid gas concentration unit includes a lean and rich liquid heat exchanger, a reboiler, an acid gas cooler, a lean liquid pump, and a rich liquid pump. The deconjugating solvent is ethanolamine or diethanolamine; The selective desulfurization solvent used is methyldiethanolamine; The gas outlet pipeline of the final stage Claus reactor of the sulfur recovery unit is connected to the inlet pipeline of the tail gas hydrogenation reactor in the tail gas treatment unit; the acid gas outlet pipeline of the tail gas regeneration tower of the tail gas treatment unit is connected to the gas inlet pipeline of the acid gas absorption tower in the acid gas concentration unit. The gas outlet pipeline of the acid gas regeneration tower of the acid gas enrichment unit is connected to the inlet pipeline of the combustion furnace of the sulfur recovery unit. The exhaust gas treatment unit employs the SCOT hydrogenation reduction absorption process and the alkanolamine method for desulfurization and decarbonization.

2. A flue gas decarbonization system for natural gas purification according to claim 1, characterized in that, The natural gas desulfurization unit also includes a purified gas separator, an acid gas separator, a lean and rich liquid heat exchanger, a lean liquid cooler, an acid gas air cooler, and a lean liquid pump.

3. The flue gas decarbonization system for natural gas purification according to claim 1, characterized in that, The natural gas desulfurization unit employs the alkanolamine process for desulfurization and decarbonization.

4. The flue gas decarbonization process using the flue gas decarbonization system according to any one of claims 1-3, characterized in that, Includes the following steps: 1) Natural gas desulfurization and decarbonization: Natural gas is passed into the natural gas desulfurization unit, where the desulfurization solution absorbs the hydrogen sulfide and carbon dioxide acidic gases in the natural gas. Then, the solution is enriched in the regeneration tower and heated to release the absorbed acidic gases. 2) Sulfur recovery: The acidic gas from step 1) is passed into the sulfur recovery unit, and more than 99% of the hydrogen sulfide in the acidic gas is converted into product sulfur through the Claus reaction. The remaining tail gas contains nitrogen, carbon dioxide and a small amount of sulfides. 3) Desulfurization and decarbonization of tail gas: The tail gas from step 2) is passed into the tail gas absorption tower and the carbon dioxide and a small amount of sulfides in the tail gas are removed by the desulfurization solvent. Then, the tail gas is regenerated in the tail gas regeneration tower with rich liquid to obtain a high carbon-to-sulfur ratio acid gas flow. 4) Acid gas enrichment: The high carbon-to-sulfur ratio acid gas from step 3) is passed through the acid gas enrichment unit. In the acid gas absorption tower, all hydrogen sulfide and a small amount of carbon dioxide are removed by selectively absorbent desulfurization solvent to obtain a high concentration of carbon dioxide gas, thus completing the decarbonization of natural gas purification flue gas.

Images