CN-121971984-A - Method and device for decarbonizing and desulfurizing refinery dry gas

CN121971984ACN 121971984 ACN121971984 ACN 121971984ACN-121971984-A

Abstract

The invention relates to the technical field of desulfurization, and discloses a method and a device for decarbonizing and desulfurizing dry gas in an oil refinery. The invention can remove hydrogen sulfide and carbon dioxide to below 1 mug/g, adopts liquid film bed high-efficiency mass transfer equipment to carry out alkali wash and mercaptan removal and water wash and alkali removal on dry gas, can ensure that the total sulfur content of purified dry gas is not more than 50mg/m 3 , the mercaptan removal alkali liquor is oxidized by adopting a catalyst-carrying fixed bed, disulfide generated by oxidation is removed by adopting liquid film bed solvent back extraction, the content of sodium mercaptide and disulfide in regenerated alkali liquor can be controlled below 10 mug/g, the regenerated alkali liquor can be recycled for a long period, the discharge amount of the mercaptan removal waste alkali liquor is reduced by more than 90 percent compared with the prior art, the oxidized tail gas is circularly used for the oxidation of the mercaptan removal alkali liquor after being pressurized and supplemented with pure oxygen, and no tail gas discharge is realized.

Inventors

XU ZHENHUA
WANG SHOUCHANG
CHEN JIANGFENG
YU ZIYAN
ZHU SHOUGAO
LIANG WEI

Assignees

宁波章甫能源科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260309

Claims (10)

1. An apparatus for decarbonizing and desulfurizing refinery dry gas, comprising: the carbonyl sulfide hydrolysis tower is internally filled with a carbonyl sulfide hydrolysis catalyst, the inlet of the side part of the bottom of the carbonyl sulfide hydrolysis tower is connected with a dry gas pipe, and the outlet of the top of the carbonyl sulfide hydrolysis tower is connected with a post-hydrolysis dry gas pipe; The top of the pre-alkaline washing tower is connected with a decarbonizing gas pipe, a pre-alkaline washing tower gas-liquid coalescer, a pre-alkaline washing alkali liquid distributor, a pre-alkaline washing tower filler and a pre-alkaline washing tower gas distributor are sequentially arranged in the pre-alkaline washing tower from top to bottom, wherein the pre-alkaline washing alkali liquid distributor is connected with an alkali liquid inlet, the alkali liquid inlet is connected with a pre-alkaline washing alkali liquid pipe, the pre-alkaline washing alkali pipe is also connected with an outlet at the bottom of the pre-alkaline washing tower and an inlet and outlet of a pre-alkaline washing pump, the inlet end of the pre-alkaline washing alkali pipe close to the pre-alkaline washing pump is also connected with an alkali liquid pipe, the pre-alkaline washing tower gas distributor is connected with a dry gas inlet, and the dry gas inlet is connected with a post-hydrolysis dry gas pipe; The top inlet of the sweetening liquid film tower is connected with one end of a decarbonization rear dry gas pipe far away from the pre-alkaline washing tower, the upper side inlet of the sweetening liquid film tower is connected with a sweetening alkali liquid pipe, the sweetening alkali liquid pipe is also connected with a regeneration alkali liquid pipe, the interior of the sweetening liquid film tower is divided into an upper area and a lower area by two sealing heads, the upper area is a sweetening liquid film bed, the lower area is a sweetening separating tank, the bottom outlet of the upper area of the sweetening liquid film tower is communicated with the side inlet in the lower area by a first connecting pipe, an alkali liquid distributor of the sweetening liquid film tower is arranged at the top of the sweetening liquid film bed and is connected with an alkali liquid inlet, a liquid film inner core of the sweetening liquid film tower is arranged in the sweetening liquid film bed, a gas-liquid coalescer of the sweetening liquid film tower is arranged at the top of the sweetening liquid film separating tank in the lower area of the sweetening liquid film tower, the top outlet of the lower area of the sweetening liquid film tower is connected with a rear dry gas pipe, and the bottom outlet of the sweetening liquid film tower is connected with the sweetening alkali liquid pipe, and the sweetening liquid circulating pump is also connected with the sweetening liquid and the upper side inlet of the sweetening liquid film tower; The top inlet of the water washing liquid film tower is connected with one end of a dry gas pipe far away from the lower region of the sweetening liquid film tower, the upper side inlet of the water washing liquid film tower is connected with a circulating water pipe, the water washing liquid film tower is divided into an upper region and a lower region by two sealing heads, the upper region of the water washing liquid film tower is a water washing liquid film bed, the lower region of the water washing liquid film tower is a water washing separating tank, the bottom outlet of the upper region of the water washing liquid film tower is communicated with the side inlet in the lower region by a second connecting pipe, a water washing liquid film tower water distributor is arranged at the top of the water washing liquid film bed and is connected with the water inlet, a water washing liquid film inner core of the water washing liquid film tower is arranged in the water washing liquid film bed, a water washing liquid film tower gas-liquid coalescer is arranged at the top of the water washing separating tank, the top outlet of the lower region of the water washing liquid film tower is connected with a purified dry gas pipe, the bottom outlet of the water washing liquid film tower is connected with a circulating water pipe, the circulating water pipe is also connected with a water washing pump and the upper side inlet of the water washing liquid film tower, the circulating water pipe is also connected with a fresh water pipe at the outlet of the water pump; The alkali liquor regeneration tower is internally provided with a tail gas liquid separating coalescer, a liquid separating groove, a catalyst fixed bed and a three-phase distributor in sequence from top to bottom, wherein the three-phase distributor is connected with a three-phase material inlet; the device comprises a mercaptan removal alkali liquor pipe, a to-be-generated alkali liquor pipe, a pure oxygen pipe, an alkali liquor regeneration tower, an oil alkali pipe, a tail gas buffer tank, a tail gas oxygen mixer, a pure oxygen pipe, a tail gas regeneration tower, an oil alkali pipe and an alkali liquor pipe, wherein the mercaptan removal alkali liquor pipe is further connected with the to-be-generated alkali liquor pipe; The anti-extraction liquid membrane bed is arranged on the oil-alkali separation tank through a flange, an alkali liquid distributor of the anti-extraction liquid membrane bed is arranged at the inner top of the anti-extraction liquid membrane bed and is connected with an alkali inlet, a liquid membrane inner core of the anti-extraction liquid membrane bed is arranged in the anti-extraction liquid membrane bed, an alkali oil baffle plate is arranged in the oil-alkali separation tank, a distribution pore plate of an coalescer of the oil-alkali separation is arranged in the oil-alkali separation tank, a coalescer of the oil-alkali separation is arranged at one side of the distribution pore plate of the coalescer of the oil-alkali separation, one end of an alkali pipe, which is far away from an alkali liquid regeneration tower, is connected with an inlet at the upper side of the anti-extraction liquid membrane bed, an outlet of the oil-alkali separation tank, which is close to the side of the anti-extraction liquid membrane bed, is connected with a circulating solvent pipe, one end of the circulating solvent pipe, which is far away from the alkali baffle plate, is connected with a solvent pump and an inlet at the top of the anti-extraction liquid membrane bed, and the circulating solvent pipe is also connected with a sulfur-containing solvent pipe at the outlet end of the solvent pump.
2. The apparatus for decarbonizing and desulfurizing dry gas in a refinery according to claim 1, wherein said apparatus for decarbonizing and desulfurizing dry gas in a refinery further comprises: The online pH value detector is arranged at the bottom outlet end of the pre-alkaline washing tower and is used for collecting the pH value data of the alkaline liquor at the bottom outlet end of the pre-alkaline washing tower in real time; the online oxygen concentration detector is arranged on the mixed tail gas pipe and is used for monitoring concentration parameters of oxygen in the mixed tail gas pipe in real time; The control module is respectively and electrically connected with the online pH value detector, the online oxygen concentration detector, the oxygen output device connected with the pure oxygen pipe and the alkali liquor throwing device connected with the alkali liquor pipe; The control module comprises a pH control unit of the pre-alkaline washing tower and an oxygen control unit of the tail gas, wherein the pH control unit of the pre-alkaline washing tower is used for controlling the alkali liquor feeding amount of the alkali liquor feeding device according to alkali liquor pH value data, constructing an alkali liquor pH value fluctuation sequence according to the alkali liquor pH value data, adjusting the alkali liquor feeding amount according to the alkali liquor pH value fluctuation sequence, and the oxygen control unit of the tail gas is used for controlling the oxygen output amount of the oxygen output device according to the concentration parameter, constructing an oxygen concentration fluctuation sequence according to the concentration parameter and adjusting the oxygen output amount according to the oxygen concentration fluctuation sequence.
3. The apparatus for decarbonizing and desulfurizing dry gas in oil refinery according to claim 2, wherein the pre-alkaline tower pH control unit is used for controlling the alkaline solution dosage of the alkaline solution dosage apparatus according to the alkaline solution pH value data, comprising: adding a preset initial alkali solution amount into the pre-alkali washing tower, and comparing alkali solution pH value data with a preset pH value setting range; when the pH value data of the alkali liquor is lower than the lower limit of the pH value setting range, an instruction for increasing the adding amount of the alkali liquor is sent to the alkali liquor adding device until the pH value data of the alkali liquor is returned to the pH value setting range; when the pH value data of the alkali liquor is higher than the upper limit of the pH value setting range, an instruction for reducing the dosage of the alkali liquor is sent to the alkali liquor adding device until the pH value data of the alkali liquor is returned to the pH value setting range.
4. The apparatus for decarbonizing and desulfurizing dry gas in oil refinery according to claim 3, wherein the pH control unit of the pre-alkaline washing tower is used for constructing an alkaline pH value fluctuation sequence according to the alkaline pH value data, and when the alkaline dosage is adjusted according to the alkaline pH value fluctuation sequence, the apparatus comprises: Continuously recording alkali liquor pH value data acquired by an online pH value detector according to a preset sampling period, and forming an alkali liquor pH value fluctuation sequence by time sequence arrangement; Trend analysis is carried out on the alkali liquor pH value fluctuation sequence, and the pH change difference value and the pH change rate in unit time between adjacent sampling points are calculated to obtain pH change gradient parameters; When the pH change gradient parameter is a descending trend and the descending rate exceeds a preset rate threshold, generating a pre-increment adjusting instruction, and proportionally increasing the alkali liquor feeding amount on the basis of the current alkali liquor feeding amount; when the pH change gradient parameter is an ascending trend and the ascending rate exceeds a preset rate threshold, generating a pre-reduction regulation instruction, and proportionally reducing the alkali liquor dosage on the basis of the current alkali liquor dosage.
5. The apparatus for decarbonizing and desulfurizing dry gas in a refinery according to claim 4, wherein said tail gas oxygen control unit for controlling the oxygen output of the oxygen output apparatus according to said concentration parameter comprises: Introducing a preset initial oxygen amount into a tail gas oxygen mixer of the alkali liquor regeneration tower, and comparing an oxygen concentration parameter in the mixed tail gas pipe with a preset oxygen concentration setting range; When the oxygen concentration parameter is lower than the lower limit of the oxygen concentration setting range, sending an instruction for increasing the output quantity of oxygen to the oxygen output device until the oxygen concentration parameter is risen back to the oxygen concentration setting range; when the oxygen concentration parameter is higher than the upper limit of the oxygen concentration setting range, an instruction for reducing the output quantity of oxygen is sent to the oxygen output device until the oxygen concentration parameter falls back into the oxygen concentration setting range.
6. The apparatus for decarbonizing and desulfurizing dry gas in oil refinery according to claim 5, wherein the tail gas oxygen control unit is used for constructing oxygen concentration fluctuation sequences according to concentration parameters, and when adjusting the oxygen output according to the oxygen concentration fluctuation sequences, the apparatus comprises: Continuously recording concentration parameters acquired by an online oxygen concentration detector according to a preset sampling period, and forming an oxygen concentration fluctuation sequence in a time sequence arrangement mode; Performing spectrum analysis on the oxygen concentration fluctuation sequence, extracting periodic characteristics and fluctuation amplitude parameters of oxygen concentration variation, and determining a main frequency period and corresponding fluctuation intensity of concentration fluctuation; When detecting that a unidirectional variation trend of a continuous preset sampling period appears in an oxygen concentration fluctuation sequence and the fluctuation amplitude exceeds a preset fluctuation threshold value, starting pre-regulation of oxygen output quantity according to a main frequency period in advance of a preset phase duration, wherein the regulation amplitude and the fluctuation intensity are positively correlated; When the oxygen concentration fluctuation sequence is detected to enter a stable fluctuation interval, the method is automatically switched to a fine adjustment mode, compensation adjustment is carried out according to a 1/4 phase difference of a current fluctuation period, and dynamic balance of the oxygen concentration in a set range is maintained, wherein the fluctuation amplitude of the stable fluctuation interval is lower than a preset fluctuation threshold value, and the duration exceeds a preset stable duration.
7. The apparatus for decarbonizing and desulfurizing dry gas in oil refinery according to claim 1, wherein the sweetening liquid film bed, the water washing liquid film bed and the back extraction liquid film bed are mass transfer devices with identical structures and materials; Wherein, the liquid film bed inner core in the sweetening liquid film bed, the washing liquid film bed and the back extraction liquid film bed comprises an inner sleeve, a pore plate, a fiber bundle hook and a fiber bundle, the fiber bundle is a large number of hydrophilic modified fiber filaments, a fiber filament base material is 304 or more stainless steel, the fiber filament diameter is 0.05-0.2mm, the surface is subjected to hydrophilic modification treatment, and the hydrophilic angle is less than or equal to 3 degrees.
8. The apparatus for decarbonizing and desulfurizing dry gas in oil refinery according to claim 1, wherein the pre-alkali washing tower gas-liquid coalescer, the sweetening liquid film tower gas-liquid coalescer and the washing liquid film tower gas-liquid coalescer are separation coalescents with the same structure and material; The fiber of the pre-alkali washing tower gas-liquid coalescer, the dithiol liquid film tower gas-liquid coalescer and the water washing liquid film tower gas-liquid coalescer is formed by weaving 304 or more stainless steel wires, the diameter of each stainless steel wire is 0.03-0.06mm, the surface is subjected to hydrophilic modification treatment, and the hydrophilic angle is smaller than or equal to 3 degrees.
9. The device for decarbonizing and desulfurizing the dry gas in the oil refinery according to claim 1, wherein the oil-alkali separation coalescer is made of 304 stainless steel or more, the distribution holes are uniformly distributed on the distribution hole plate of the coalescer, the flow rate of the material passing through the distribution hole is in the range of 0.01-0.05m/s, the fiber of the coalescing piece of the oil-alkali separation coalescer is formed by mixing 304 stainless steel wires and polyphenylene sulfide or polytetrafluoroethylene fiber, the diameter of the stainless steel wires is 0.03-0.06mm, the surface is subjected to special hydrophilic modification treatment, the hydrophilic angle is less than or equal to 3 degrees, and the diameter of the polyphenylene sulfide or polytetrafluoroethylene fiber is 0.01-0.03mm.
10. A method for decarbonizing and desulfurizing refinery dry gas, which is applied to the device for decarbonizing and desulfurizing refinery dry gas according to any one of claims 1 to 9, and is characterized by comprising the following steps: The sulfur-containing dry gas passes through a carbonyl sulfide hydrolysis catalyst bed layer in a carbonyl sulfide hydrolysis tower from bottom to top, and under the action of the carbonyl sulfide hydrolysis catalyst, carbonyl sulfide in the sulfur-containing dry gas and trace water in the sulfur-containing dry gas undergo hydrolysis reaction to generate hydrogen sulfide and carbon dioxide; The hydrolyzed sulfur-containing dry gas enters the pre-caustic tower from an inlet at the lower side part of the pre-caustic tower, is uniformly distributed on the cross section of the pre-caustic tower through a gas distributor of the pre-caustic tower and rises, the pre-caustic lye is pressurized and circulated through a pre-caustic pump, is uniformly distributed on the cross section of a filler in the tower through a pre-caustic lye distributor, gas-liquid two phases are in countercurrent and fully contacted between the fillers, carbon dioxide in the sulfur-containing dry gas reacts with sodium hydroxide in the lye, the pH value of the circulating lye is controlled through discharging waste liquid and supplementing the flow of lye, and the dry gas after pre-caustic washing is sent to a mercaptan removal liquid film tower after the lye is separated through a gas-liquid coalescer of the pre-caustic tower at the top of the pre-caustic tower; The method comprises the steps that dry gas after pre-alkali washing enters a sweetening liquid film bed in the upper area of a sweetening liquid film tower from a top inlet, circulating alkali liquid from a sweetening alkali liquid circulating pump and regenerated alkali liquid from a regenerated alkali liquid pump enter the sweetening liquid film bed from an upper side inlet, alkali liquid spreads on the surface of hydrophilic fiber filaments to form a water phase film, the dry gas after pre-alkali washing passes through fiber filaments, the mass transfer distance from mercaptan in the dry gas after pre-alkali washing and sodium hydroxide in the alkali liquid to a gas-liquid two-phase contact surface is greatly shortened, mercaptan in the dry gas after pre-alkali washing and sodium hydroxide in the alkali liquid are fully contacted and quickly reacted, generated sodium mercaptide is dissolved in the alkali liquid, dry gas after sweetening enters a sweetening liquid film separating tank from a bottom outlet of the sweetening liquid film bed through a pipeline from a side inlet, dry gas and the alkali liquid are further separated through a sweetening liquid film tower gas-liquid coalescer at the top of the sweetening liquid separating tank after preliminary separation, and partial to-liquid to-be-regenerated liquid in the sweetening liquid film bed after the sodium mercaptide is dissolved, and partial dry gas after the mercaptan is sent to the regenerating tower from the top outlet of the sweetening liquid film separating tank; The dry gas after alkali washing is carried with trace alkali liquor, the dry gas after mercaptan removal enters a water washing liquid film bed in the upper area of the water washing liquid film tower from a top inlet, circulating water from a water washing pump enters the water washing liquid film bed from an upper side inlet, water spreads on the surface of hydrophilic fiber filaments to form a water phase film, the dry gas passes through the fiber filaments, trace alkali liquor carried in the dry gas fully contacts with the water and is rapidly extracted and fed into the water to realize the dealkalization of the dry gas; The to-be-generated alkali liquor from the mercaptan removal liquid film tower, the circulating tail gas after supplementing oxygen and the low sulfur solvent are mixed by a three-phase mixer, then enter the alkali liquor regeneration tower from the bottom inlet, are uniformly distributed on the cross section of the tower by a three-phase distributor at the bottom of the alkali liquor regeneration tower, slowly flow upwards from bottom to top through a fixed bed layer loaded with sulfonated phthalocyanine cobalt catalyst, react with oxygen in the tail gas under the action of the catalyst to generate sodium hydroxide and disulfide, the sodium hydroxide is dissolved in the alkali liquor, and the disulfide is extracted into the solvent as an oil phase; The tail gas after oxidation reaction is discharged from an ejection outlet of an alkali liquor regeneration tower after liquid phase separation is carried out by a tail gas liquid separation coalescer at the top of the alkali liquor regeneration tower, the tail gas is pressurized by a tail gas booster and is mixed with supplementary oxygen by a tail gas oxygen mixer, an online oxygen content detector is arranged on a mixed tail gas pipeline, and the flow of the supplementary oxygen is automatically controlled, so that the oxygen content in the mixed tail gas is controlled within the range of 19-23%v; After separating tail gas from a liquid separating tank at the upper part of an alkali liquid regeneration tower, pressing and conveying the mixed liquid of alkali liquid and solvent to an anti-extraction liquid film bed from an outlet at the liquid separating tank, enabling the mixed liquid of alkali liquid and solvent to enter the anti-extraction liquid film bed from an inlet at the upper side, enabling circulating solvent to enter the anti-extraction liquid film bed from the top, delaying the surface of a large number of hydrophilic fiber filaments in the anti-extraction liquid film bed to form a water phase film, enabling the solvent to pass through the fiber filaments, further extracting disulfide remained in the alkali liquid into the solvent, enabling the alkali liquid and the solvent to flow to an oil-alkali separation tank for sedimentation separation, enabling the upper-layer solvent and the lower-layer alkali liquid after sedimentation separation to uniformly distribute and flow through an oil-alkali separation coalescer coalescing element when flowing through an oil-alkali separation coalescer distribution pore plate, enabling alkali liquid drops carried by the upper-layer solvent to coalesce to grow to form large alkali liquid drops when contacting hydrophilic stainless steel wires, and enabling the alkali drops to drop into the alkali liquid at the lower layer of the separation tank under the action of polarity difference and gravity; when the tiny oil drops carried by the alkali liquor at the lower layer contact the hydrophobic polymer fiber yarn, the tiny oil drops coalesce and grow to form larger oil drops, the larger oil drops float up to the solvent at the upper layer of the oil-alkali separation tank under the action of polarity difference and buoyancy, so that the oil-alkali is quickly and thoroughly separated, wherein the solvent/alkali liquor interface position in the oil-alkali separation tank is controlled to be not more than 50%, the regenerated alkali liquor after the oil-alkali separation enters a sweetening liquid film tower for circulation through a regenerated alkali liquid pump for dry gas sweetening, sulfur-containing solvent overflows an oil-alkali baffle plate to enter a solvent area, the sulfur-containing solvent enters an anti-pumping liquid film bed through the pressurization of a solvent pump in a part of circulation mode, and the part of the regenerated alkali liquor is pumped out of the device.

Description

Method and device for decarbonizing and desulfurizing refinery dry gas Technical Field The invention relates to the technical field of desulfurization, in particular to a method and a device for decarbonizing and desulfurizing refinery dry gas. Background The dry gas of the oil refinery contains complex components and hydrocarbons such as hydrogen, methane, ethane, ethylene and the like, a small amount of C, C and C-tetra alkane alkene and air, trace amounts of sulfides such as C.penta-alkane alkene, CO 2, H 2S、COS、CH3SH、C2H5SH、CH3SCH3, etc. The fuel gas has various applications, the total sulfur is required to be less than or equal to 50mg/m 3 as the fuel gas to meet the SO 2 emission standard, and the total sulfur is required to be more severe as the chemical raw material. The prior desulfurization technology has the limitations that although the MDEA amine liquid extraction and the Lo-CAT process can remove hydrogen sulfide, the process is complex, the investment and operation cost are high, the organic sulfur cannot be removed, and the method is not suitable for dry gas after the amine liquid extraction. The extraction and regeneration process of the organic sulfur removal is usually carried out by using sodium hydroxide alkali liquor, but the acidity of CO 2 and H 2 S is stronger than that of mercaptan, a large amount of catalyst alkali liquor is consumed and the mercaptan removal effect is affected, so that CO 2 and H 2 S are removed by pretreatment, the COS hydrolysis rate is slow, CO 2 and H 2 S are required to be pretreated by hydrolysis catalyst, the properties of thioether and carbon disulfide are stable, the removal of the thioether and the carbon disulfide is difficult, and the adsorption method and other higher cost technologies are required. Accordingly, there is a need for a method and apparatus for decarbonizing and desulfurizing refinery dry gas that solves at least one of the above-mentioned problems of the prior art. Disclosure of Invention In view of the above, the present invention provides a method and apparatus for decarbonizing and desulfurizing dry gas in a refinery, which aims to solve at least one of the problems in the prior art. In one aspect, the invention provides a device for decarbonizing and desulfurizing refinery dry gas, which comprises: the carbonyl sulfide hydrolysis tower is internally filled with a carbonyl sulfide hydrolysis catalyst, the inlet of the side part of the bottom of the carbonyl sulfide hydrolysis tower is connected with a dry gas pipe, and the outlet of the top of the carbonyl sulfide hydrolysis tower is connected with a post-hydrolysis dry gas pipe; The top of the pre-alkaline washing tower is connected with a decarbonizing gas pipe, a pre-alkaline washing tower gas-liquid coalescer, a pre-alkaline washing alkali liquid distributor, a pre-alkaline washing tower filler and a pre-alkaline washing tower gas distributor are sequentially arranged in the pre-alkaline washing tower from top to bottom, wherein the pre-alkaline washing alkali liquid distributor is connected with an alkali liquid inlet, the alkali liquid inlet is connected with a pre-alkaline washing alkali liquid pipe, the pre-alkaline washing alkali pipe is also connected with an outlet at the bottom of the pre-alkaline washing tower and an inlet and outlet of a pre-alkaline washing pump, the inlet end of the pre-alkaline washing alkali pipe close to the pre-alkaline washing pump is also connected with an alkali liquid pipe, the pre-alkaline washing tower gas distributor is connected with a dry gas inlet, and the dry gas inlet is connected with a post-hydrolysis dry gas pipe; The top inlet of the sweetening liquid film tower is connected with one end of a decarbonization rear dry gas pipe far away from the pre-alkaline washing tower, the upper side inlet of the sweetening liquid film tower is connected with a sweetening alkali liquid pipe, the sweetening alkali liquid pipe is also connected with a regeneration alkali liquid pipe, the interior of the sweetening liquid film tower is divided into an upper area and a lower area by two sealing heads, the upper area is a sweetening liquid film bed, the lower area is a sweetening separating tank, the bottom outlet of the upper area of the sweetening liquid film tower is communicated with the side inlet in the lower area by a first connecting pipe, an alkali liquid distributor of the sweetening liquid film tower is arranged at the top of the sweetening liquid film bed and is connected with an alkali liquid inlet, a liquid film inner core of the sweetening liquid film tower is arranged in the sweetening liquid film bed, a gas-liquid coalescer of the sweetening liquid film tower is arranged at the top of the sweetening liquid film separating tank in the lower area of the sweetening liquid film tower, the top outlet of the lower area of the sweetening liquid film tower is connected with a rear dry gas pipe, and the bottom outlet of the sweetening liquid