A skid-mounted LNG deacidification device and method

Abstract

The present invention discloses a skid-mounted LNG deacidification device and method, which solves the technical problems of the deacidification device in the prior art, such as the complex structure, high production and configuration cost, and difficulty in later maintenance and overhaul of the equipment. The device comprises a combined absorption tower (100), a combined regeneration tower (200), a lean-rich amine heat exchanger (313), a lean amine cooler (304), an amine storage tank (300), and a lean amine pump (302). The combined absorption tower (100) is provided with a cooling chamber (103), a separation chamber (102), and an absorption chamber (101) from top to bottom, and a liquid distributor (115) is also provided at the top of the absorption chamber (101). The present invention provides a skid-mounted LNG deacidification device and method, which reduces the number of equipment, pipelines, and valves by conveniently skidding or modularizing the deacidification device and combining the equipment, thereby reducing the investment in the deacidification system and achieving the same deacidification effect and purification index.

Description

Technical Field

[0001] The invention belongs to the field of energy technology, and in particular relates to a skid-mounted LNG deacidification device and method. Background Art

[0002] Natural gas, whose main component is methane, only produces carbon dioxide and water molecules after full combustion. It is recognized as the cleanest fossil energy on earth. Liquefied natural gas (LNG) is a liquid condensed from natural gas after purification, cooling, and supercooling to -162°C, and is stored in a low-temperature storage tank at 0.1MPa. The processed LNG has the advantages of being colorless, odorless, non-toxic and non-corrosive. Its volume is about 1 / 625 of the volume of the same amount of gaseous natural gas, and the mass of liquefied natural gas is only about 45% of the same volume of water, which greatly saves energy storage space.

[0003] However, before natural gas is liquefied at low temperature to obtain LNG, the natural gas produced by the gas field needs to be purified to remove corrosive and low-temperature solidified impurities in the natural gas directly produced from the gas field. This mainly includes three parts: deacidification, dehydration and demercuration. Among them, the deacidification part is an important concern in the purification process of LNG production regarding energy consumption, equipment protection and safe production.

[0004] In the prior art, the acid gas removal technology widely used in the field of natural gas treatment and processing is the MDEA absorption process. The MDEA acid removal process utilizes the performance of MDEA aqueous solution to dissolve the acid gas in the gas at room temperature and desorb the acid gas under high temperature and low pressure conditions, thereby removing the acid gas in the natural gas, avoiding corrosion to the equipment during the storage of LNG, and maintaining the safety of LNG storage.

[0005] Among the existing patents, patent application number CN200810044270.7, named "Front-end combined purification process for producing liquefied natural gas from methane-rich mixed gas", patent application number CN201520326787.0, named "A carbon dioxide removal device in the process of producing liquefied natural gas from coke oven gas", patent application number CN201620389925.4, named "A desulfurization and decarbonization system for synthetic natural gas", patent application number CN202010558598.1, named "An energy-saving natural gas MDEA The patents for "Decarbonization System and Decarbonization Process Thereof", "A Energy-Saving Natural Gas MDEA Decarbonization Device and Method" with patent application number CN202011171092.1, and "LNG Decarbonization System Based on MDEA Solvent" with patent application number CN202021764682.0 all use the MDEA absorption method to remove acid gas from LNG. However, the devices used in the above patents have the defects of numerous equipment and complex systems, which are not conducive to the operation of the deacidification device in subsequent use, and are more difficult to troubleshoot and repair in subsequent faults. Summary of the invention

[0006] The object of the present invention is to provide a skid-mounted LNG deacidification device and method to solve the technical problems in the prior art of complex structure of the deacidification device, high production and configuration costs, and difficult subsequent maintenance and overhaul of the equipment.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a skid-mounted LNG deacidification device, comprising a combined absorption tower, a combined regeneration tower, a lean-rich amine heat exchanger, a lean amine cooler, an amine storage tank and a lean amine pump;

[0009] The combined absorption tower is provided with a cooling chamber 1, a separation chamber 1 and an absorption chamber in sequence from top to bottom, a liquid distributor 1 is also provided at the top of the absorption chamber, the absorption chamber is connected to the cooling chamber 1 by a steam pipe 1, the cooling chamber 1 and the separation chamber 1 are connected by a channel of a cooling pipe, and a flooding pipe 1 connected to the liquid distributor 1 is provided at the bottom of the separation chamber 1; a natural gas inlet pipe for entering the natural gas to be treated and a tower bottom outlet pipe for discharging the rich amine solution are provided at the bottom end of the absorption chamber of the combined absorption tower, a lean amine liquid inlet pipe for entering the lean amine solution is also provided on the liquid distributor 1, and a natural gas outlet pipe for discharging the deacidified natural gas is provided in the separation chamber 1;

[0010] The combined regeneration tower is provided with cooling chamber 2, desorption chamber, separation chamber 2 and reboiler in sequence from top to bottom. The top of the desorption chamber is also provided with liquid distributor 2. The desorption chamber is connected to cooling chamber 2 through steam pipe 2. The cooling chamber 2 is connected to separation chamber 2 through the channel of cooling pipe. The bottom of separation chamber 2 is provided with liquid overflow pipe 2 connected to liquid distributor 2. The reboiler is provided with lean amine outlet pipe for outputting treated lean amine solution. The separation chamber 2 is also connected with acid gas outlet pipe for outputting acid-containing gas. The liquid distributor 2 is also connected with rich amine inlet pipe for entering rich amine gas.

[0011] The tower bottom outlet pipe is connected to the rich amine inlet pipe, and a lean-rich amine heat exchanger is also provided on the connecting pipe between the tower bottom outlet pipe and the rich amine inlet pipe; the lean amine outlet pipe is connected to the amine storage tank, and a lean-rich amine heat exchanger is also provided on the connecting pipe between the lean amine outlet pipe and the amine storage tank; the amine storage tank is connected to the lean amine liquid inlet pipe, and a lean amine pump and a lean amine cooler are also provided on the connecting pipe between the amine storage tank and the lean amine liquid inlet pipe;

[0012] The cooling chamber 1, cooling chamber 2 and lean amine cooler are respectively provided with a cold source inlet pipe and a cold source outlet pipe; the reboiler is provided with a heat source inlet pipe and a heat source outlet pipe; the amine storage tank is also provided with a nitrogen inlet pipe 1 for nitrogen entry and a chemical inlet pipe for chemicals entry; the separation chamber 2 is also provided with a nitrogen inlet pipe 2 for nitrogen entry.

[0013] Optionally or preferably, the outside of the combined absorption tower is further provided with a reflux overflow pipe 1 connecting the separation chamber 1 and the bottom end of the combined absorption tower; the outside of the combined regeneration tower is further provided with a reflux overflow pipe 2 connecting the separation chamber 2 and the bottom end of the combined regeneration tower.

[0014] Optionally or preferably, the outlet pipe end of the lean amine cooler is further provided with a reflux pipe connected to the amine storage tank, and the reflux pipe is provided with a pipe filter 1, a lean amine filter and a pipe filter 2 in sequence along the flow direction of the lean amine.

[0015] Optionally or preferably, the cold source inlet pipe and the heat source inlet pipe are respectively provided with control valves for the heat source and the cold source inlet and outlet; the connecting pipe between the lean amine cooler and the liquid distributor 1 is provided with a control valve and a double check valve; the reflux pipe is also provided with a control valve; the nitrogen inlet pipe 1 and the nitrogen inlet pipe 2 are respectively provided with control valves; the tower bottom pipe is also provided with a liquid level control valve and a low liquid level cut-off valve.

[0016] Optionally or preferably, the absorption chamber of the absorption tower is a packed tower;

[0017] The reboiler is any one of a kettle reboiler, a thermosyphon reboiler, a forced circulation reboiler and a built-in reboiler, and the heat source of the reboiler is any one of a power supply, heat transfer oil and natural gas;

[0018] The cold source of the cooling chamber 1, the cooling chamber 2 and the lean amine cooler can be any one of circulating cooling water, circulating chilled water, propane, refrigerant and low-temperature raw natural gas.

[0019] Optionally or preferably, the cooling chamber 1 and the separation chamber 1 of the combined absorption tower are arranged in combination, and the cooling chamber 1 and the separation chamber 1 arranged in combination can be separately arranged outside the absorption chamber and have the same height as the top of the absorption chamber; the steam pipe 1 connects the cooling chamber 1 and the absorption chamber, and the overflow pipe 1 connects the separation chamber 1 and the bottom of the combined absorption tower.

[0020] Optionally or preferably, the cooling chamber 2 and the separation chamber 2 of the combined regeneration tower are arranged in combination, and the cooling chamber 2 and the separation chamber 2 arranged in combination can be separately arranged outside the decomposition chamber and have the same height as the top of the decomposition chamber; the steam pipe 2 connects the cooling chamber 2 and the decomposition chamber, and the overflow pipe 2 connects the separation chamber 2 and the bottom of the combined regeneration tower.

[0021] The present invention provides a deacidification method for a skid-mounted LNG deacidification device, comprising the following steps:

[0022] a. The raw natural gas to be deacidified is input into the combined absorption tower, and contacts with the descending amine liquid in the absorption chamber. The deacidified natural gas entering the top of the absorption chamber of the absorption tower enters the cooling chamber through the steam pipe 1 and is cooled by the cold source, and the condensed water is separated in the separation chamber 1. Finally, the deacidified natural gas leaves the combined absorption tower through the natural gas outlet pipe, and the condensed water in the separation chamber 1 enters the liquid distributor 1 along the flooding pipe 1;

[0023] b. The rich amine liquid that has absorbed the acid gas enters the lean-rich amine heat exchanger from the bottom outlet pipe of the combined absorption tower, and enters the liquid distributor 2 of the combined regeneration tower along the rich amine inlet pipe after being heated to 90-105°C. The rich amine liquid contacts the rising water vapor from top to bottom in the desorption chamber. The amine liquid enters the reboiler and is heated again to regenerate into lean amine liquid. The acid gas at the top of the desorption chamber enters the cooling chamber 2 along the steam pipe 2 to condense, and the condensed water is separated in the separation chamber 2. Finally, the acid gas leaves the combined regeneration tower through the acid gas outlet pipe, and the condensed water in the separation chamber 2 enters the liquid distributor 2 along the flooding pipe 2;

[0024] c. The lean amine liquid regenerated in the combined regeneration tower enters the lean-rich amine heat exchanger along the lean amine outlet pipe, and after being cooled to 55-75°C, enters the amine storage tank; the lean amine in the amine storage tank enters the lean amine pump for pressurization, and then enters the lean amine cooler to be cooled by the cold source. The cooled lean amine liquid enters the liquid distributor 1 of the combined absorption tower, thus completing the amine liquid circulation.

[0025] Optionally or preferably, the step further includes: 75-90% of the lean amine liquid cooled by the lean amine cooler in step c enters the liquid distributor 1 of the combined absorption tower, and 10-25% of the cooled lean amine liquid returns to the amine storage tank along the reflux pipeline, sequentially passing through the pipeline filter 1, the lean amine filter and the pipeline filter 2.

[0026] Optionally or preferably, the raw natural gas to be deacidified has a pressure of 0.5 MPa to 10.0 MPa and a temperature of 5 to 55° C., and the raw natural gas to be deacidified also includes various hydrocarbon gases rich in methane.

[0027] Based on the above technical solution, the embodiments of the present invention can at least produce the following technical effects:

[0028] The skid-mounted LNG deacidification device and method provided by the present invention provide a deacidification device that is convenient for skid mounting or modularization. Through the cooling chamber and separation chamber arranged on the top of the combined regeneration tower and the combined absorption tower, the gaseous water in the acid gas is condensed and recovered to the lower end of the tower body by gravity, thereby avoiding the setting of a reflux pump and reducing the cost of acid gas recovery. In addition, the setting of the combined absorption tower and the combined regeneration tower reduces the number of equipment, pipelines and valves, reduces the investment in the deacidification system, and can achieve the same deacidification effect and purification indicators. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of Embodiment 1 of the present invention;

[0030] Figure 2 is a schematic structural diagram of Embodiment 2 of the present invention;

[0031] Figure 3 It is a structural diagram of embodiment 3 of the present invention.

[0032] In the figure: 100, combined absorption tower; 101, absorption chamber; 102, separation chamber 1; 103, cooling chamber 1; 104, reflux overflow pipe 1; 111, natural gas inlet pipe; 112, steam pipe 1; 113, natural gas outlet pipe; 114, overflow pipe 1; 115, liquid distributor 1; 200, combined regeneration tower; 201, analysis chamber; 202, separation chamber 2; 203, cooling chamber 2; 204, liquid distributor 2; 205, overflow pipe 2; 300, amine storage tank; 302, lean amine pump; 304, lean amine cooler; 30 7. Double check valve; 308. Lean amine liquid inlet pipe; 309. Tower bottom outlet pipe; 310. Liquid level control valve; 311. Low liquid level cut-off valve; 313. Lean-rich amine heat exchanger; 314. Rich amine inlet pipe; 315. Reboiler; 316. Lean amine outlet pipe; 321. Reflux pipeline; 323. Pipeline filter one; 324. Lean amine filter; 325. Pipeline filter two; 332. Nitrogen inlet pipe one; 333. Chemical inlet pipe; 361. Nitrogen inlet pipe two; 371. Steam pipeline two; 372. Acid gas outlet pipe; 374. Reflux overflow pipe two. DETAILED DESCRIPTION

[0033] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0034] Example 1

[0035] like Figure 1 As shown:

[0036] The present invention provides a skid-mounted LNG deacidification device, comprising a combined absorption tower 100, a combined regeneration tower 200, a lean-rich amine heat exchanger 313, a lean amine cooler 304, an amine storage tank 300 and a lean amine pump 302;

[0037] The combined absorption tower 100 is provided with a cooling chamber 103, a separation chamber 102 and an absorption chamber 101 in sequence from top to bottom, and a liquid distributor 115 is also provided at the top of the absorption chamber 101. The absorption chamber 101 is connected to the cooling chamber 103 via a steam pipe 112, and the cooling chamber 103 is connected to the separation chamber 102 via a cooling pipe channel. The bottom of the separation chamber 102 is provided with a flooding pipe 114 connected to the liquid distributor 115; a natural gas inlet pipe 111 for entering the natural gas to be treated and a tower bottom outlet pipe 309 for discharging the rich amine solution are provided at the bottom of the absorption chamber 101 of the combined absorption tower 100, a lean amine liquid inlet pipe 308 for entering the lean amine solution is also provided on the liquid distributor 115, and the separation chamber 102 is provided with a natural gas outlet pipe 113 for discharging the deacidified natural gas;

[0038] The combined regeneration tower 200 is provided with a cooling chamber 203, a desorption chamber 201, a separation chamber 202 and a reboiler 315 in sequence from top to bottom. A liquid distributor 204 is also provided at the top of the desorption chamber 201. The desorption chamber 201 is connected to the cooling chamber 203 through a steam pipe 371. The cooling chamber 203 and the separation chamber 202 are connected through a cooling pipe channel. A liquid overflow pipe 205 connected to the liquid distributor 204 is provided at the bottom of the separation chamber 202. A lean amine outlet pipe 316 for outputting the treated lean amine solution is provided on the reboiler 315. The separation chamber 202 is also connected to an acid gas outlet pipe 372 for outputting acid-containing gas. The liquid distributor 204 is also connected to a rich amine inlet pipe 314 for entering rich amine gas.

[0039] The tower bottom outlet pipe 309 is connected to the rich amine inlet pipe 314, and a lean-rich amine heat exchanger 313 is further provided on the connecting pipe between the tower bottom outlet pipe 309 and the rich amine inlet pipe 314; the lean amine outlet pipe 316 is connected to the amine storage tank 300, and a lean-rich amine heat exchanger 313 is further provided on the connecting pipe between the lean amine outlet pipe 316 and the amine storage tank 300; the amine storage tank 300 is connected to the lean amine liquid inlet pipe 308, and a lean amine pump 302 and a lean amine cooler 304 are further provided on the connecting pipe between the amine storage tank 300 and the lean amine liquid inlet pipe 308;

[0040] The cooling chamber 1 103, the cooling chamber 2 203 and the lean amine cooler 304 are respectively provided with a cold source inlet pipe and a cold source outlet pipe; the reboiler 315 is provided with a heat source inlet pipe and a heat source outlet pipe; the amine storage tank 300 is also provided with a nitrogen inlet pipe 1 332 for nitrogen entry and a chemical inlet pipe 333 for chemicals entry; the separation chamber 2 202 is also provided with a nitrogen inlet pipe 2 361 for nitrogen entry.

[0041] When the device of the present invention is in use, the acid gas is transferred from natural gas to amine solution in the absorption chamber 101 of the combined absorption tower 100, and a natural gas product and rich amine liquid are produced; the rich amine liquid contacts the rising water vapor from top to bottom in the desorption chamber 201 of the combined regeneration tower 200, desorbs the acid substances into the water vapor, and falls into the reboiler 315 to regenerate lean amine liquid and return to the combined absorption tower. The molar ratio content index of the acid gas in the natural gas after deacidification is: CO2 content is 20-100ppm, H2S≤4ppm.

[0042] As an optional embodiment, the combined absorption tower 100 is further provided with a reflux overflow pipe 104 connecting the separation chamber 102 and the bottom end of the combined absorption tower 100 on the outside; the combined regeneration tower 200 is further provided with a reflux overflow pipe 374 connecting the separation chamber 202 and the bottom end of the combined regeneration tower 200 on the outside.

[0043] The reflux flooding pipe 1 104 and the reflux flooding pipe 2 374 can help to reflux the excess solution accumulated in the separation chamber, maintain the normal use of the device, and avoid the occurrence of flooding.

[0044] As an optional embodiment, the outlet pipe end of the lean amine cooler 304 is also provided with a reflux pipe 321 connected to the amine storage tank 300, and the reflux pipe 321 is provided with a pipe filter 1 323, a lean amine filter 324 and a pipe filter 2 325 in sequence along the flow direction of the lean amine.

[0045] As an optional embodiment, the cold source inlet pipe and the heat source inlet pipe are respectively provided with control valves for the heat source and the cold source inlet and outlet; the connecting pipe between the lean amine cooler 304 and the liquid distributor 115 is provided with a control valve and a double check valve 307; the reflux pipe 321 is also provided with a control valve; the nitrogen inlet pipe 1 332 and the nitrogen inlet pipe 2 361 are respectively provided with control valves; the tower bottom pipe is also provided with a liquid level control valve 310 and a low liquid level cut-off valve 311.

[0046] As an optional embodiment, the absorption chamber 101 of the combined absorption tower 100 is a packed tower;

[0047] The reboiler 315 is any one of a kettle reboiler 315, a thermosyphon reboiler 315, a forced circulation reboiler 315 and a built-in reboiler 315, and the heat source of the reboiler 315 is any one of a power source, heat transfer oil and natural gas;

[0048] The cold source of the cooling chamber 1 103, the cooling chamber 2 203 and the lean amine cooler 304 may be any one of circulating cooling water, circulating chilled water, propane, refrigerant and low-temperature raw natural gas.

[0049] Example 2

[0050] like Figure 2 As shown:

[0051] The present invention provides a skid-mounted LNG deacidification device. Compared with Example 1, the cooling chamber 103 and the separation chamber 102 of the combined absorption tower 100 of Example 2 are combined, and the combined cooling chamber 103 and the separation chamber 102 can be separately arranged outside the absorption chamber 101, and the height is equal to the top of the absorption chamber 101; the steam pipe 112 connects the cooling chamber 103 and the absorption chamber 101, and the overflow pipe 114 connects the separation chamber 102 and the bottom of the combined absorption tower 100.

[0052] The cooling chamber 203 and the separation chamber 202 of the combined regeneration tower 200 are arranged in combination, and the cooling chamber 203 and the separation chamber 202 arranged in combination can be separately arranged outside the decomposition chamber 201, and the height is equal to the top of the decomposition chamber 201; the steam pipe 2 371 connects the cooling chamber 203 and the decomposition chamber 201, and the overflow pipe 205 connects the separation chamber 202 and the bottom of the combined regeneration tower 200.

[0053] Part of the components of the combined absorption tower 100 and the combined regeneration tower 200 are disassembled for installation, so that the skids can be transported separately when the transportation length is limited.

[0054] Example 3

[0055] like Figure 3 As shown:

[0056] The present invention provides a skid-mounted LNG deacidification device. Compared with Example 2, Example 3 installs the reflux pipeline 321 and the pipeline filter 1 323, the lean amine filter 324 and the pipeline filter 2 325 arranged in sequence on the reflux pipeline 321 on the pipeline between the lean amine cooler 304 and the lean amine liquid inlet pipe 308.

[0057] Experimental example

[0058] The present invention provides a deacidification method for a skid-mounted LNG deacidification device, comprising the following steps:

[0059] a. The raw natural gas to be deacidified is input into the combined absorption tower 100, and contacts with the descending amine liquid in the absorption chamber 101. The deacidified natural gas entering the top of the absorption chamber 101 of the absorption tower enters the cooling chamber 103 through the steam pipe 112, and is cooled by the cold source, and the condensed water is separated in the separation chamber 102. Finally, the deacidified natural gas leaves the combined absorption tower 100 through the natural gas outlet pipe 113, and the condensed water in the separation chamber 102 enters the liquid distributor 115 along the flooding pipe 114;

[0060] b. The rich amine liquid that has absorbed the acid gas enters the lean-rich amine heat exchanger 313 from the bottom outlet pipe 309 of the combined absorption tower 100, and enters the liquid distributor 204 of the combined regeneration tower 200 along the rich amine inlet pipe 314 after being heated to 90-105°C. The rich amine liquid contacts the rising water vapor from top to bottom in the desorption chamber 201, and the amine liquid enters the reboiler 315 and is heated again to regenerate into lean amine liquid. The acid gas at the top of the desorption chamber 201 enters the cooling chamber 203 along the steam pipe 371 to condense, and the condensed water is separated in the separation chamber 202. Finally, the acid gas leaves the combined regeneration tower 200 through the acid gas outlet pipe 372, and the condensed water in the separation chamber 202 enters the liquid distributor 204 along the flooding pipe 205;

[0061] c. The lean amine liquid regenerated in the combined regeneration tower 200 enters the lean-rich amine heat exchanger 313 along the lean amine outlet pipe 316, and after being cooled to 55-75°C therein, enters the amine storage tank 300; the lean amine in the amine storage tank 300 enters the lean amine pump 302 for pressurization, and then enters the lean amine cooler 304 to be cooled by the cold source, and the cooled lean amine liquid enters the liquid distributor 115 of the combined absorption tower 100, thereby completing the amine liquid circulation.

[0062] As an optional embodiment, the step also includes: 75-90% of the lean amine liquid cooled by the lean amine cooler 304 in step c enters the liquid distributor 115 of the combined absorption tower 100, and 10-25% of the cooled lean amine liquid returns to the amine storage tank 300 along the reflux pipe 321, successively through the pipe filter 1 323, the lean amine filter 324 and the pipe filter 2 325.

[0063] As an optional embodiment, the raw natural gas to be treated for deacidification has a pressure of 0.5 MPa to 10.0 MPa and a temperature of 5 to 55° C., and the raw natural gas to be treated for deacidification also includes various hydrocarbon gases rich in methane.

[0064] The natural gas system parameters of the inlet and outlet of the acid gas removal system in Example 1 are shown in Table 1:

[0065] Table 1 Natural gas system parameters

[0066]

[0067]

[0068] The natural gas system parameters of the inlet and outlet of the acid gas removal system in Example 2 are shown in Table 2:

[0069] Table 2 Natural gas system parameters

[0070]

[0071] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A skid-mounted LNG deacidification device, characterized in that: It comprises a combined absorption tower (100), a combined regeneration tower (200), a lean-rich amine heat exchanger (313), a lean amine cooler (304), an amine storage tank (300) and a lean amine pump (302); The combined absorption tower (100) is provided with a cooling chamber (103), a separation chamber (102) and an absorption chamber (101) in order from top to bottom. A liquid distributor (115) is also provided at the top of the absorption chamber (101). The absorption chamber (101) is connected to the cooling chamber (103) via a steam pipe (112). The cooling chamber (103) is connected to the separation chamber (102) via a cooling pipe channel. The bottom of the separation chamber (102) is provided with a liquid distributor (115). A flooding pipe (114) connected to a liquid distributor (115) is provided; a natural gas inlet pipe (111) for the natural gas to be treated and a tower bottom outlet pipe (309) for discharging a rich amine solution are provided at the bottom of the absorption chamber (101) of the combined absorption tower (100); a lean amine liquid inlet pipe (308) for the lean amine solution is also provided on the liquid distributor (115); and a natural gas outlet pipe (113) for discharging deacidified natural gas is provided on the separation chamber (102); The combined absorption tower (100) is also provided with a reflux flooding pipe (104) connecting the separation chamber (102) and the bottom end of the combined absorption tower (100) on the outside; the combined regeneration tower (200) is also provided with a reflux flooding pipe (374) connecting the separation chamber (202) and the bottom end of the combined regeneration tower (200) on the outside; The absorption chamber (101) of the combined absorption tower is a packed tower; The combined regeneration tower (200) is provided with a cooling chamber (203), a desorption chamber (201), a separation chamber (202) and a reboiler (315) in order from top to bottom. A liquid distributor (204) is also provided at the top of the desorption chamber (201). The desorption chamber (201) is connected to the cooling chamber (203) via a steam pipe (371). The cooling chamber (203) is connected to the separation chamber (202) via a cooling pipe channel. A liquid flooding pipe (205) connected to the liquid distributor (204) is provided at the bottom of the separation chamber (202). A lean amine outlet pipe (316) for outputting a treated lean amine solution is provided on the reboiler (315). The separation chamber (202) is also connected to an acid gas outlet pipe (372) for outputting acid-containing gas. The liquid distributor (204) is also connected to a rich amine inlet pipe (314) for entering rich amine gas. The tower bottom outlet pipe (309) is connected to the rich amine inlet pipe (314), and a lean-rich amine heat exchanger (313) is further provided on the connecting pipe between the tower bottom outlet pipe (309) and the rich amine inlet pipe (314); the lean amine outlet pipe (316) is connected to the amine storage tank (300), and a lean-rich amine heat exchanger (313) is further provided on the connecting pipe between the lean amine outlet pipe (316) and the amine storage tank (300); the amine storage tank (300) is connected to the lean amine liquid inlet pipe (308), and a lean amine pump (302) and a lean amine cooler (304) are further provided on the connecting pipe between the amine storage tank (300) and the lean amine liquid inlet pipe (308); The cooling chamber 1 (103), the cooling chamber 2 (203) and the lean amine cooler (304) are respectively provided with a cold source inlet pipe and a cold source outlet pipe; the reboiler (315) is provided with a heat source inlet pipe and a heat source outlet pipe; the amine storage tank (300) is also provided with a nitrogen inlet pipe 1 (332) for nitrogen to enter and a chemical inlet pipe (333) for chemicals to enter; the separation chamber 2 (202) is also provided with a nitrogen inlet pipe 2 (361) for nitrogen to enter; The reboiler (315) is any one of a kettle reboiler (315), a thermosyphon reboiler (315), a forced circulation reboiler (315) and a built-in reboiler (315), and the heat source of the reboiler (315) is any one of a power source, heat transfer oil and natural gas; The cold source of the cooling chamber 1 (103), the cooling chamber 2 (203) and the lean amine cooler (304) is any one of circulating cooling water, circulating chilled water, refrigerant and low-temperature raw natural gas.

2. A skid-mounted LNG deacidification device according to claim 1, characterized in that: The outlet pipe end of the lean amine cooler (304) is also provided with a reflux pipe (321) connected to the amine storage tank (300), and the reflux pipe (321) is provided with a pipe filter 1 (323), a lean amine filter (324) and a pipe filter 2 (325) in sequence along the flow direction of the lean amine.

3. A skid-mounted LNG deacidification device according to claim 2, characterized in that: The cold source inlet pipe and the heat source inlet pipe are respectively provided with control valves for the heat source and the cold source inlet and outlet; the connecting pipe between the lean amine cooler (304) and the first liquid distributor (115) is provided with a control valve and a double check valve (307); the reflux pipe (321) is also provided with a control valve; the nitrogen inlet pipe (332) and the nitrogen inlet pipe (361) are respectively provided with control valves; and the tower bottom pipe is also provided with a liquid level control valve (310) and a low liquid level cut-off valve (311).

4. The skid-mounted LNG deacidification device according to claim 1, characterized in that: The cooling chamber 1 (103) and the separation chamber 1 (102) of the combined absorption tower (100) are arranged in combination, and the cooling chamber 1 (103) and the separation chamber 1 (102) arranged in combination are arranged separately outside the absorption chamber (101) and at the same height as the top of the absorption chamber (101); the steam pipe 1 (112) connects the cooling chamber 1 (103) and the absorption chamber (101), and the flooding pipe 1 (114) connects the separation chamber 1 (102) and the bottom of the combined absorption tower (100).

5. The skid-mounted LNG deacidification device according to claim 1, characterized in that: The cooling chamber 2 (203) and the separation chamber 2 (202) of the combined regeneration tower (200) are arranged in combination, and the cooling chamber 2 (203) and the separation chamber 2 (202) arranged in combination are arranged separately outside the desorption chamber (201) and at the same height as the top of the desorption chamber (201); the steam pipe 2 (371) connects the cooling chamber 2 (203) and the desorption chamber (201), and the flooding pipe 2 (205) connects the separation chamber 2 (202) and the bottom of the combined regeneration tower (200).

6. A deacidification method for a skid-mounted LNG deacidification device according to any one of claims 1 to 5, characterized in that: The following steps are involved: a. The raw natural gas to be deacidified is input into the combined absorption tower (100), and contacts with the descending amine liquid in the absorption chamber (101). The deacidified natural gas entering the top of the absorption chamber (101) enters the cooling chamber (103) via the steam pipe (112) and is cooled by the cold source. Condensed water is separated in the separation chamber (102). Finally, the deacidified natural gas leaves the combined absorption tower (100) via the natural gas outlet pipe (113). The condensed water in the separation chamber (102) enters the liquid distributor (115) along the flooding pipe (114); b. The rich amine liquid that has absorbed the acid gas enters the lean-rich amine heat exchanger (313) from the bottom outlet pipe (309) of the combined absorption tower (100), is heated to 90-105°C, and then enters the second liquid distributor (204) of the combined regeneration tower (200) along the rich amine inlet pipe (314). The rich amine liquid contacts the rising water vapor from top to bottom in the desorption chamber (201). The amine liquid enters the reboiler (315) and is heated again to regenerate into lean amine liquid. The acid gas at the top of the desorption chamber (201) enters the second cooling chamber (203) along the second steam pipe (371) to be condensed, and the condensed water is separated in the second separation chamber (202). Finally, the acid gas leaves the combined regeneration tower (200) through the acid gas outlet pipe (372), and the condensed water in the second separation chamber (202) enters the second liquid distributor (204) along the second flooding pipe (205); c. The lean amine liquid regenerated in the combined regeneration tower (200) enters the lean-rich amine heat exchanger (313) along the lean amine outlet pipe (316), and after being cooled to 55-75°C, enters the amine storage tank (300); the lean amine in the amine storage tank (300) enters the lean amine pump (302) for pressurization, and then enters the lean amine cooler (304) to be cooled by the cold source. The cooled lean amine liquid enters the liquid distributor 1 (115) of the combined absorption tower (100), thereby completing the amine liquid circulation.

7. The deacidification method of a skid-mounted LNG deacidification device according to claim 6, characterized in that: The step also includes: 75-90% of the lean amine liquid cooled by the lean amine cooler (304) in step c enters the liquid distributor 1 (115) of the combined absorption tower (100), and 10-25% of the lean amine liquid returns to the amine storage tank (300) along the reflux pipeline (321), sequentially passes through the pipeline filter 1 (323), the lean amine filter (324) and the pipeline filter 2 (325).

8. The deacidification method of a skid-mounted LNG deacidification device according to claim 6, characterized in that: The raw natural gas to be treated with deacidification has a pressure of 0.5 MPa to 10.0 MPa and a temperature of 5 to 55° C., and the raw natural gas to be treated with deacidification also includes various hydrocarbon gases rich in methane.

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