CN114262636B - Natural gas desulfurization and decarburization system and method - Google Patents

Natural gas desulfurization and decarburization system and method Download PDF

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CN114262636B
CN114262636B CN202111502040.2A CN202111502040A CN114262636B CN 114262636 B CN114262636 B CN 114262636B CN 202111502040 A CN202111502040 A CN 202111502040A CN 114262636 B CN114262636 B CN 114262636B
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gas
infinitesimal
absorption
separator
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CN114262636A (en
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蓝兴英
李成祥
崔怡洲
石孝刚
高金森
徐春明
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China University of Petroleum Beijing
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China University of Petroleum Beijing
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Abstract

The invention discloses a natural gas desulfurization and decarburization system and a method. In the system and the method for desulfurizing and decarbonizing natural gas, the natural gas and the absorption liquid are dispersed into a micron-scale infinitesimal dispersion system in the infinitesimal generation device, so that the system has huge phase interface area, the absorption rate is obviously improved, the infinitesimal generation device is used for replacing conventional tower equipment, the size is small, and the size of the absorption equipment is greatly reduced.

Description

Natural gas desulfurization and decarburization system and method
Technical Field
The invention relates to a method for removing carbon dioxide and hydrogen sulfide in natural gas based on a wet desulphurization and decarbonization technology, and belongs to the technical field of natural gas purification.
Background
With the improvement of natural gas industrial infrastructure in China, the development speed is accelerated continuously, the natural gas industrial chain in China enters a rapid development stage, the demand of natural gas is increased sharply, and based on the industrial background that the domestic urbanization process is accelerated, the energy-saving and environment-friendly demand is increased, and the infrastructure and policy are improved continuously, the application range of the natural gas is expanded continuously after years of development, and the natural gas is gradually advanced to main energy. The requirement of China on the content of sulfur in natural gas is more and more strict, and the content of hydrogen sulfide is required to be lower than 6mg/m in one class of standards in GB 17820-2018 3 The carbon dioxide content is less than 3mol%, so that the requirements for desulfurization methods are also increasing.
The absorption method is one of the most widely applied natural gas desulfurization and decarburization processes. The absorption liquid used in the absorption process can be divided into chemical solvent, physical solvent and physical-chemical solvent, and can be selected according to the composition of natural gas and actual conditions. Specifically, the catalyst comprises single-component or multi-component organic amine solution of alcohol amines such as MDEA, TEA, MEA, DGA, DEA, DIPA, TBEE, TBIPE and the like, or organic amine solution added with an activating agent and an auxiliary agent, sulfone amine and the like.
The existing absorption equipment mainly comprises a plate tower and a packed tower and is limited by the lower mass transfer efficiency of the traditional tower equipment, the equipment volume is larger, and the device is largerThe energy consumption is also high, so the goal of strengthening the mass transfer process of the absorption equipment to achieve the reduction of the equipment size and the realization of low consumption and high efficiency is always an important direction for developing the natural gas desulfurization technology. In particular, with the development of the natural gas industry, the throughput is rapidly increased, and the problem of the large-scale high-pressure absorption tower equipment is more and more prominent. Therefore, in addition to improving the process flow, the following two aspects are mainly developed: on one hand, the mass transfer efficiency can be improved on the basis of the conventional absorption tower, and on the other hand, novel mass transfer enhancement equipment such as a rotating packed bed and the like can be developed. Chinese patent CN202808741U proposes a natural gas desulfurization and decarburization deep purification system, which can not only carry out conventional purification of sulfur-containing raw material natural gas to meet the purification index requirements of common commodity natural gas, but also can deeply remove H in the raw material natural gas once 2 S、CO 2 And mercaptan, COS and other organic sulfur impurities, are common natural gas desulfurization processes at present, and the absorption equipment in the patent is a conventional absorption tower. Chinese patent CN109988659A proposes a natural gas desulfurization system and method, which adds a TSA desulfurization unit on the basis of an MDEA desulfurization unit to deeply remove hydrogen sulfide, but the system is more complex and the used equipment is more. Chinese patent CN203096016U provides a composite plate-type absorption tower, which can effectively realize desulfurization and decarburization of natural gas by an alcohol amine method, improve the operation stability of the absorption tower, and ensure the working efficiency of the absorption tower. Chinese patent CN103756743A proposes a method for removing hydrogen sulfide from low-content hydrogen sulfide raw material gas, which adopts an absorption oxidation method, utilizes a rotating packed bed to strengthen absorption reaction, simplifies the process flow, reduces the equipment, saves the occupied area, and is suitable for offshore platforms.
However, the conventional absorption tower is difficult to greatly improve the desulfurization and decarburization efficiency through improvement and optimization, the strengthening effect is very limited, and although the rotary packed bed technology can greatly reduce the equipment volume and realize high selectivity, the rotary packed bed technology needs to ensure long-term stable operation as mobile equipment, and the removal rate needs to be paid attention to when natural gas with high hydrogen sulfide and carbon dioxide content is treated. From the perspective of mass transfer, the mass transfer can be enhanced by improving the flow state to enable the gas and the liquid to generate a larger phase interface and improving the turbulence degree of the gas and the liquid, and further the absorption reaction is enhanced. The dispersion degree of gas-liquid two phases in conventional tower equipment is not high, and the phase interface area is small; in the rotating packed bed, the liquid phase is dispersed into liquid films, liquid filaments and liquid drops, the interfacial area is large, the gas-liquid retention time is short, the selectivity is kept while the absorption reaction rate is improved, and the size of the dispersed phase still has a space for further reducing.
Disclosure of Invention
In order to solve the problems of low gas-liquid two-phase dispersion degree, large equipment volume and low purification efficiency in the conventional natural gas desulfurization and decarburization method, the invention aims to provide a natural gas desulfurization and decarburization system and a natural gas desulfurization and decarburization method. The natural gas decarbonization method provided by the invention is suitable for treating the natural gas with the hydrogen sulfide content lower than 0.8mol% and the carbon dioxide content lower than 8mol%.
In a first aspect, the invention provides a natural gas enhanced desulfurization and decarbonization system, which comprises a raw material gas pretreatment system, a first acid gas absorption system, a second acid gas absorption system, a flash evaporation system and an absorption liquid regeneration system;
the raw material gas pretreatment system comprises a raw material gas gravity separator and a raw material gas filtering separator; the outlet of the feed gas gravity separator is connected with the inlet of the feed gas filtering separator;
the first acid gas absorption system comprises a first infinitesimal generation device and a first gas-liquid separator; the outlet of the feed gas filtering separator is connected with the gas phase inlet of the first infinitesimal generation device; the outlet of the first infinitesimal generation device is connected with the inlet of the first gas-liquid separator;
the second acid gas absorption system comprises a second infinitesimal generation device and a second gas-liquid separator; the gas-phase outlet of the first gas-liquid separator is connected with the gas-phase inlet of the second infinitesimal generating device; the outlet of the second micro element generating device is connected with the inlet of the second gas-liquid separator;
the flash system comprises a pressure reduction device and a flash tank; the pressure reduction device is a turbine or a pressure reduction valve;
the liquid phase outlets of the first gas-liquid separator and the second gas-liquid separator are connected by 1) or 2) as follows:
1) The liquid phase outlet of the first gas-liquid separator is connected with the flash tank through the pressure reduction device; a liquid phase outlet of the second gas-liquid separator is connected with an inlet of the first infinitesimal generation device through a rich liquid circulating pump;
2) The liquid phase outlet of the first gas-liquid separator is divided into two paths, one path is connected with the flash tank through the pressure reduction device, and the other path is connected with the liquid phase inlet of the first infinitesimal generation device through a rich liquid circulating pump; the liquid phase outlet of the second gas-liquid separator is connected with the inlet of the first gas-liquid separator through a rich liquid circulating pump;
the absorption liquid regeneration system comprises a regeneration tower, a tower top condenser, an absorption liquid storage and configuration device, a regeneration tower reflux tank and a reboiler; the flash tank is connected with an inlet at the middle upper part of the regeneration tower through a lean and rich absorption liquid heat exchanger; the top outlet of the regeneration tower is sequentially connected with the tower top condenser and the regeneration tower reflux tank; the liquid phase outlet at the bottom of the regeneration tower reflux tank is connected with the inlet at the middle upper part of the regeneration tower through a regeneration tower reflux pump; the bottom liquid phase outlet of the regeneration tower is connected with the reboiler; an outlet at the bottom of the reboiler is connected with the lean and rich absorption liquid heat exchanger through a lean liquid delivery pump, the lean and rich absorption liquid heat exchanger is connected with a lean absorption liquid cooler, the absorption liquid storage and configuration device is connected with an inlet of the lean absorption liquid cooler, an outlet of the lean absorption liquid cooler is divided into two paths, one path is connected with the filtering and purifying device and then converged with the other path, and the two paths are connected with an inlet of the second infinitesimal generation device through a lean liquid booster pump.
In the system, the infinitesimal generating device is a device capable of cutting a gas-liquid two-phase system into infinitesimal with the size of 1-800 mu m;
the micro-element generating device includes, but is not limited to, one or more of a microporous membrane (with a pore size of 1-500,000 nanometers), a Venturi type micro-bubble generating device, an ultrasonic cavitation device, a hydrodynamic cavitation type micro-bubble generating device (for example, a hydrodynamic cavitation part of a micro-bubble generator in patent CN201811308335.4 and a clothes treatment device), a centrifugal type micro-bubble generating device (for example, a centrifugal type micro-bubble generating device in patent CN 202020030699.7), a jet type micro-bubble generating device, and a swirling type micro-bubble generating device, which are connected in series and/or in parallel.
In the specific embodiment of the invention, the micro element generating device adopts a structural design of an axial cyclone type microbubble generator and a device disclosed in a numerical simulation DOI (DOI: 10.12034/j.issn.1009-606 X.217413), wherein a microporous plate used for gas injection has the average aperture of 50 micrometers, the liquid phase inlet diameter of 10cm, the inner diameter of a Venturi throat of 3cm, and 4 micro plates are connected in parallel.
In the above system, the first gas-liquid separator and the second gas-liquid separator are gas-liquid separators capable of separating gas bubbles of 30 μm or more from the liquid phase;
the gas-liquid separator includes, but is not limited to, one or more of a centrifugal separator, a gravity separator, a baffled separator, a packed separator, a wire mesh separator, a microporous filtration separator, in series and/or in parallel.
In the system, the two paths at the outlet of the lean absorption liquid cooler are converged and then divided into two paths again, one path is connected with the inlet of the second gas-liquid separator through the lean liquid booster pump, and the other path is connected with the filler column of the flash tank.
In a second aspect, the invention provides a method for desulfurizing and decarbonizing natural gas, comprising the following steps:
(1) Pretreating the natural gas feed gas to remove solid particles and liquid drops in the natural gas feed gas;
the pretreated natural gas and the circulating rich solution enter a first infinitesimal generating device to be dispersed into a first infinitesimal dispersion system with micron scale, acid gas in the first infinitesimal dispersion system and absorption liquid are subjected to absorption reaction, and the reacted first infinitesimal dispersion system enters a first gas-liquid separator to be separated into first crude decarbonized natural gas and first rich absorption liquid;
the first coarse decarbonized natural gas and the poor absorption liquid enter a second infinitesimal generating device to be dispersed into a second infinitesimal dispersion system with a micron scale, acid gas in the second infinitesimal dispersion system and the absorption liquid are subjected to absorption reaction, and the reacted second infinitesimal dispersion system enters a second gas-liquid separator to be separated into fine decarbonized natural gas and a second rich absorption liquid;
(2) The first rich absorption liquid and the second rich absorption liquid are conveyed by the following 1) or 2);
1) The first rich absorption liquid is subjected to pressure reduction through a turbine or a pressure reducing valve and then enters a flash tank for flash evaporation; the second rich absorption liquid is conveyed to the first infinitesimal generation device by a rich liquid circulating pump to be used as the circulating rich liquid in the step (1);
2) The first rich absorption liquid is divided into two parts, one part is conveyed to the first infinitesimal generation device by a rich liquid circulating pump to be used as the circulating rich liquid in the step (1), and the other part enters a flash tank for flash evaporation after being subjected to pressure reduction by a turbine or a pressure reducing valve; the second rich absorption liquid is conveyed to the first gas-liquid separator through a rich liquid circulating pump;
(3) Hydrogen sulfide in flash gas flowing out of the top of the flash tank is removed, the flash gas enters a fuel gas system, and rich absorption liquid flowing out of a liquid phase outlet of the flash tank enters a lean-rich absorption liquid heat exchanger;
the rich absorption liquid flowing out of the liquid phase outlet of the flash tank exchanges heat with the regenerated lean absorption liquid, the temperature is raised, the rich absorption liquid enters the upper inlet of the regeneration tower, the acid gas in the natural gas enriched in the absorption liquid is desorbed and discharged from the top of the regeneration tower, the natural gas is condensed by a condenser at the top of the regeneration tower and enters a reflux tank of the regeneration tower, the separated acid gas is discharged from a gas phase outlet at the top of the reflux tank of the regeneration tower, the separated reflux liquid is discharged from a liquid phase outlet at the bottom of the reflux tank of the regeneration tower and is sent back to the top of the regeneration tower through a reflux pump of the regeneration tower; liquid flowing out of a liquid phase outlet at the bottom of the regeneration tower enters a reboiler at the bottom of the regeneration tower, one part of the liquid is heated in the reboiler and is gasified and returned to the bottom of the regeneration tower, and the other part of the liquid is discharged from an outlet at the bottom of the reboiler and is used as the regenerated lean absorption liquid to enter the lean absorption liquid heat exchanger;
and (2) exchanging heat between the regenerated lean absorption liquid and rich absorption liquid flowing out of a liquid phase outlet of the flash tank, cooling, merging with supplementary absorption liquid from an absorption liquid storage and configuration unit, then feeding into a lean absorption liquid cooler for further cooling, dividing into two parts after cooling, feeding one part into a filtering and purifying unit for removing impurities, then re-merging with the other part, and conveying to the second infinitesimal generation device by a lean liquid booster pump to serve as the lean absorption liquid in the step (1).
In the method, the first infinitesimal dispersion system and the second infinitesimal dispersion system are respectively generated by a first infinitesimal generating device and a second infinitesimal generating device, both are in a micrometer scale, and absorption reaction of the absorption liquid and acidic gases such as hydrogen sulfide, carbon dioxide and the like in the natural gas simultaneously occurs in the first infinitesimal dispersion system and the second infinitesimal dispersion system. Because the gas-liquid two-phase interfacial area in the infinitesimal dispersion system is huge, the turbulence degree is high, the absorption reaction is strengthened, and only a small reaction volume is needed to carry out the reaction of H 2 S and CO 2 The standard is lower than the national standard.
In the above method, in step (1), the step of pre-treating may be as follows: the natural gas feed gas enters a gravity separator to separate large-particle liquid drops and solid impurities, and then enters a feed gas filtering separator to remove small solid particles and liquid drops.
In the above method, the absorption solution may be various chemical, physical or chemical-physical solvents, including single-component, multi-component or organic amine solutions with activators and auxiliaries, such as alcohol amines, e.g., MDEA, TEA, MEA, DGA, DEA, DIPA, TBEE, TBIPE, and the like, and sulfone amines, and the like.
In the above process, the first and second infinitesimal dispersions may have a size of 1 to 800 μm, preferably 50 to 350 μm, for example an average size of 350 μm.
In the method, the operating pressure of the first infinitesimal generating device and the second infinitesimal generating device can be 3-15 MPa, and the operating temperature can be 30-80 MPaThe gas-liquid ratio can be 200-5000 Nm 3 /m 3 Preferably 200 to 1000Nm 3 /m 3 。
In the above method, the content of hydrogen sulfide in the natural gas feed gas is less than 0.8mol%, and the content of carbon dioxide is less than 8mol%.
The invention has the following beneficial effects:
in the system and the method for desulfurizing and decarbonizing natural gas, natural gas and absorption liquid are dispersed into a micron-scale infinitesimal dispersion system in the infinitesimal generator, so that the system has huge phase interface area, the absorption rate is obviously improved, the infinitesimal generator is used for replacing conventional tower equipment, the size is small, and the size of the absorption equipment is greatly reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the embodiments or the prior art description will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings may be obtained according to these drawings without inventive labor.
FIG. 1 is a process flow diagram of a desulfurization and decarbonization method for natural gas according to example 1 of the present invention.
In fig. 1, the respective symbols are as follows:
1-raw material gas; 2-gravity separator of raw material gas; 3-raw material gas filtering separator; 4-pretreating natural gas; 5-circulating the rich solution; 6-a first infinitesimal generating device; 7-a first infinitesimal dispersion; 8-a first gas-liquid separator; 9-first crude decarbonized natural gas; 10-a first rich absorption liquid; 11 21-lean absorption liquid; 12-a second infinitesimal generating device; 13-a second infinitesimal dispersion; 14-a second gas-liquid separator; 15-fine desulfurization and decarbonization of natural gas; 16-a second rich absorption liquid; 17-rich liquid circulating pump; 18-turbine; 19-a flash tank; 20-flash evaporation gas; 22-a filler section; 23-lean rich absorption liquid heat exchanger; 24-a regeneration column; 25-overhead condenser; 26-a regeneration tower reflux tank; 27-acid gas; 28-regeneration tower reflux pump; 29-a reboiler; 30-saturated steam; 31-lean liquor delivery pump; 32-an absorption liquid storage and dispensing unit; 33-lean absorption liquid cooler; 34-a filtration purification device; 35-lean liquor booster pump.
FIG. 2 is a process flow diagram of a method for desulfurizing and decarbonizing natural gas according to example 2 of the present invention.
In fig. 2, the respective symbols are as follows:
1-raw material gas; 2-gravity separator of raw material gas; 3-raw material gas filtering separator; 4-pretreating natural gas; 5-circulating the rich liquid; 6-a first infinitesimal generating device; 7-a first infinitesimal dispersion; 8-a first gas-liquid separator; 9-first crude decarbonized natural gas; 10, 11-a first rich absorption liquid; 12 23-lean absorption liquid; 13-second infinitesimal generating means; 14-a second infinitesimal dispersion; 15-a second gas-liquid separator; 16-fine desulfurization and decarbonization of natural gas; 17-a second rich absorption liquid; 18-a second rich liquid circulating pump; 19-a first rich liquor circulating pump; 20-turbine; 21-a flash tank; 22-flash evaporation gas; 24-a filler section; 25-lean rich absorption liquid heat exchanger; 26-a regeneration tower; 27-overhead condenser; 28-regeneration tower reflux tank; 29-acid gas; 30-a regeneration tower reflux pump; 31-a reboiler; 32-saturated steam; 33-lean liquor delivery pump; 34-an absorption liquid storage and dispensing unit; 35-lean absorption liquid cooler; 36-a filtration purification unit; 37-lean solution booster pump.
Detailed Description
The natural gas desulfurization and decarburization system provided by the invention comprises a raw material gas pretreatment system, a first acid gas absorption system, a second acid gas absorption system, a flash evaporation system and an absorption liquid regeneration system;
the raw material gas pretreatment system comprises a raw material gas gravity separator and a raw material gas filtering separator; the outlet of the raw material gas gravity separator is connected with the inlet of the raw material gas filtering separator;
the first acid gas absorption system comprises a first infinitesimal generation device and a first gas-liquid separator; the outlet of the feed gas filtering separator is connected with the gas phase inlet of the first infinitesimal generating device; the outlet of the first infinitesimal generation device is connected with the inlet of the first gas-liquid separator;
the second acid gas absorption system comprises a second infinitesimal generation device and a second gas-liquid separator; the gas-phase outlet of the first gas-liquid separator is connected with the gas-phase inlet of the second infinitesimal generating device; the outlet of the second micro element generating device is connected with the inlet of the second gas-liquid separator;
the flash evaporation system comprises a pressure reduction device and a flash evaporation tank; the pressure reduction device is a turbine or a pressure reduction valve;
the liquid phase outlets of the first gas-liquid separator and the second gas-liquid separator are connected by 1) or 2) as follows:
1) The liquid phase outlet of the first gas-liquid separator is connected with the flash tank through the pressure reduction device; a liquid phase outlet of the second gas-liquid separator is connected with an inlet of the first infinitesimal generation device through a rich liquid circulating pump;
2) The liquid phase outlet of the first gas-liquid separator is divided into two paths, one path is connected with the flash tank through the pressure reduction device, and the other path is connected with the liquid phase inlet of the first infinitesimal generation device through a rich liquid circulating pump; the liquid phase outlet of the second gas-liquid separator is connected with the inlet of the first gas-liquid separator through a rich liquid circulating pump;
the absorption liquid regeneration system comprises a regeneration tower, a tower top condenser, an absorption liquid storage and configuration device, a regeneration tower reflux tank and a reboiler; the flash tank is connected with an inlet at the middle upper part of the regeneration tower through a lean and rich absorption liquid heat exchanger; the top outlet of the regeneration tower is sequentially connected with the tower top condenser and the regeneration tower reflux tank; a liquid phase outlet at the bottom of the regeneration tower reflux tank is connected with an inlet at the middle upper part of the regeneration tower through a regeneration tower reflux pump; the liquid phase outlet at the bottom of the regeneration tower is connected with the reboiler; an outlet at the bottom of the reboiler is connected with the lean and rich absorption liquid heat exchanger through a lean liquid delivery pump, the lean and rich absorption liquid heat exchanger is connected with a lean absorption liquid cooler, the absorption liquid storage and configuration device is connected with an inlet of the lean absorption liquid cooler, an outlet of the lean absorption liquid cooler is divided into two paths, one path is connected with the filtering and purifying device and then converged with the other path, and the two paths are connected with an inlet of the second infinitesimal generation device through a lean liquid booster pump.
According to the invention, the scale of the first infinitesimal dispersion system and the second infinitesimal dispersion system has an influence on the enhancement degree of the absorption reaction, the scale of the infinitesimal dispersion system is related to the infinitesimal generating device and the flow rate of the absorption liquid entering the infinitesimal generating device, generally speaking, the scale of the infinitesimal dispersion system can be reduced by increasing the flow rate of the absorption liquid, and the absorption performance is improved, therefore, the scale of the infinitesimal dispersion system can be regulated and controlled by adding extra absorption liquid circulation to the infinitesimal generating device and the first gas-liquid separator, the absorption liquid circulation is driven by a circulating pump, but considering that a certain mass transfer driving force needs to be kept, the second infinitesimal generating device is not suitable for adding the absorption liquid circulation. Namely, the liquid phase outlet of the first gas-liquid separator can be connected with the liquid phase inlet of the first infinitesimal generation device through a rich liquid circulating pump. Correspondingly, in order to ensure the reasonability of the process, the connection modes between the first rich absorption liquid and the second rich absorption liquid and each device also need to be adjusted correspondingly, and the specific setting method is explained with reference to the attached drawings. For example, the liquid phase outlet of the first gas-liquid separator is connected with the liquid phase inlet of the first infinitesimal generation device through a rich liquid circulating pump; and a liquid phase outlet of the second gas-liquid separator is connected with an inlet of the first gas-liquid separator through a rich liquid circulating pump.
As shown in fig. 1, the natural gas desulfurization and decarbonization system comprises a raw gas pretreatment system, a first acid gas absorption system, a second acid gas absorption system, a flash evaporation system and an absorption liquid regeneration system;
the raw material gas pretreatment system comprises a raw material gas gravity separator 2 and a raw material gas filtering separator 3; the outlet of the raw material gas gravity separator 2 is connected with the inlet of the raw material gas filtering separator 3;
the first acid gas absorption system comprises a first infinitesimal generation device 6 and a first gas-liquid separator 8; the outlet of the raw material gas filtering separator 3 is connected with the gas phase inlet of the first infinitesimal generating device 6; the outlet of the first infinitesimal generation device 6 is connected with the inlet of the first gas-liquid separator 8;
the second acid gas absorption system comprises a second infinitesimal generation device 12 and a second gas-liquid separator 14; the gas phase outlet of the first gas-liquid separator 8 is connected with the gas phase inlet of the second infinitesimal generating device 12; the outlet of the second micro-element generating device 12 is connected with the inlet of the second gas-liquid separator 14; the liquid phase outlet of the second gas-liquid separator 14 is connected with the liquid phase inlet of the first infinitesimal generation device 6 through a rich liquid circulating pump 17;
the flash system comprises a turbine 18 and a flash tank 19; the liquid phase outlet of the first gas-liquid separator 8 is connected with a flash tank 19 through a turbine 18;
the absorption liquid regeneration system comprises a regeneration tower 24, an overhead condenser 25, an absorption liquid storage and configuration device 32, a regeneration tower reflux tank 26 and a reboiler 29; the flash tank 19 is connected with an inlet at the middle upper part of a regeneration tower 24 through a lean-rich absorption liquid heat exchanger 23; the top outlet of the regeneration tower 24 is connected with an overhead condenser 25 and a regeneration tower reflux tank 26 in sequence; a liquid phase outlet at the bottom of the regeneration tower reflux tank 26 is connected with an inlet at the middle upper part of the regeneration tower 24 through a regeneration tower reflux pump 28; the liquid phase outlet at the bottom of the regeneration tower 24 is connected with a reboiler 29; an outlet at the bottom of the reboiler 29 is connected with a lean and rich absorption liquid heat exchanger 23 through a lean liquid delivery pump 31, the lean and rich absorption liquid heat exchanger 23 is connected with a lean absorption liquid cooler 33, an absorption liquid storage and configuration device 32 is connected with an inlet of the lean absorption liquid cooler 33, an outlet of the lean absorption liquid cooler 33 is divided into two paths, one path is connected with a filtering and purifying device 34 and then converged with the other path, the two paths are divided into two paths again, one path is connected with an inlet of the second infinitesimal generation device 12 through a lean liquid booster pump 35, and the other path is connected with a filler column 22 of the flash tank 19.
As shown in fig. 1, a raw gas 1 enters a gravity separator 2 to separate large particle droplets and solid impurities, then enters a raw gas filtering separator 3 to remove small solid particles and droplets possibly carried in the gas to obtain pretreated natural gas 4, and then enters a first infinitesimal generator 6 with an absorption liquid from a circulating pump 17 of a rich liquid (circulating rich liquid) 5 to generate a first infinitesimal dispersion system 7 with a micron scale (the size is 1-800 μm, and the optimal value is 50-350 μm), and simultaneously, an acidic gas in the natural gas and the absorption liquid perform an absorption reaction, and a desulfurization and decarburization reaction is performed in the first infinitesimal dispersion system. Then enters a first gas-liquid separator 8 for gas-liquid separation, a first crude decarbonized natural gas 9 is discharged from a top gas-phase outlet, and a first rich absorption liquid 10 is discharged from a bottom liquid-phase outlet. The first crude decarbonized natural gas 9 and the lean absorption liquid 11 from the lean liquid booster pump 35 are dispersed into a second infinitesimal dispersion system 13 (with the size of 1-800 μm and the optimal value of 50-350 μm) with micron scale in a second infinitesimal generation device 12, and the desulfurization and decarbonization reaction of the absorption liquid simultaneously occurs. Then, the second infinitesimal dispersion system 13 is separated into a gas-liquid two-phase in a second gas-liquid separator 14, the gas phase is the fine desulfurized and decarbonized natural gas 15, the gas phase enters a subsequent purification process, and the liquid phase is a second rich absorption liquid 16 and is conveyed to the first infinitesimal generation device 6 through a rich liquid circulating pump 17. The first rich absorption liquid 10 from the liquid phase outlet of the first gas-liquid separator 8 is depressurized by a turbine 18 and enters a flash tank 19 for flash evaporation, and the flash vapor 20 and the lean absorption liquid 21 are in countercurrent contact in a packed column 22 to remove hydrogen sulfide and then are discharged from a device and enter a fuel gas system. The rich absorption liquid flowing out of the liquid phase outlet of the flash tank 19 enters a lean absorption liquid heat exchanger 23, exchanges heat with the regenerated lean absorption liquid, then is heated, and enters an inlet at the middle upper part of the regeneration tower 24. The top outlet of the regeneration tower 24 is sequentially connected with a tower top condenser 25 and a regeneration tower reflux tank 26, acid gas 27 is discharged from a gas phase outlet at the top of the regeneration tower reflux tank 26, reflux liquid is discharged from a liquid phase outlet at the bottom of the regeneration tower reflux tank 26, and the reflux liquid is conveyed back to the tower top of the regeneration tower 24 through a regeneration tower reflux pump 28; the liquid phase outlet at the bottom of the regeneration tower 24 is connected with a reboiler 29 at the bottom of the regeneration tower, saturated steam 30 is used as a heat source, the absorption liquid is heated in the reboiler 29 and is partially gasified, the absorption liquid returns to the bottom of the regeneration tower 24, the other part of the liquid is discharged from the outlet at the bottom of the reboiler 29 and is used as regenerated lean absorption liquid, the lean absorption liquid is conveyed to enter a lean rich absorption liquid heat exchanger 23 through a lean liquid conveying pump 31 to be cooled, the lean absorption liquid is merged with supplemented absorption liquid from an absorption liquid storage and configuration unit 32 and then enters a lean absorption liquid cooler 33 to be further cooled, the cooled lean absorption liquid is divided into two parts, one part of the lean absorption liquid enters a filtering and purifying device 34 to be re-merged with the other part of the lean absorption liquid which is not filtered and purified, the merged lean absorption liquid is divided into a small part 21 to enter a filler column 22 in a flash tank, and the rest part of the lean absorption liquid is pressurized through a lean liquid booster pump 35 and then enters a liquid phase inlet of a second infinitesimal generation device 12, so that the cyclic utilization of the absorption liquid is realized.
As shown in fig. 2, the natural gas desulfurization and decarbonization system comprises a raw gas pretreatment system, a first acid gas absorption system, a second acid gas absorption system, a flash evaporation system and an absorption liquid regeneration system;
the raw material gas pretreatment system comprises a raw material gas gravity separator 2 and a raw material gas filtering separator 3; the outlet of the raw material gas gravity separator 2 is connected with the inlet of the raw material gas filtering separator 3;
the first acid gas absorption system comprises a first infinitesimal generation device 6 and a first gas-liquid separator 8; the outlet of the raw material gas filtering separator 3 is connected with the gas phase inlet of the first infinitesimal generating device 6; the outlet of the first infinitesimal generation device 6 is connected with the inlet of the first gas-liquid separator 8;
the second acid gas absorption system comprises a second infinitesimal generation device 13 and a second gas-liquid separator 15; the gas phase outlet of the first gas-liquid separator 8 is connected with the gas phase inlet of the second infinitesimal generating device 13; the outlet of the second micro element generator 13 is connected with the inlet of the second gas-liquid separator 15; the liquid phase outlet of the second gas-liquid separator 15 is connected with the inlet of the first gas-liquid separator 8 through a second rich liquid circulating pump 18;
the flash system comprises a turbine 20 and a flash tank 21; the liquid phase outlet of the first gas-liquid separator 8 is divided into two paths, one path is connected with a flash tank 21 through a turbine 20, and the other path is connected with the liquid phase inlet of the first infinitesimal generation device 6 through a first rich liquid circulating pump 19;
the absorption liquid regeneration system comprises a regeneration tower 26, an overhead condenser 27, an absorption liquid storage and configuration device 34, a regeneration tower reflux tank 28 and a reboiler 31; the flash tank 21 is connected with an inlet at the middle upper part of a regeneration tower 26 through a lean rich absorption liquid heat exchanger 25; the top outlet of the regeneration tower 26 is connected with an overhead condenser 27 and a regeneration tower reflux tank 28 in sequence; a liquid phase outlet at the bottom of the regeneration tower reflux tank 28 is connected with an inlet at the middle upper part of the regeneration tower 26 through a regeneration tower reflux pump 30; the liquid phase outlet at the bottom of the regeneration tower 26 is connected with a reboiler 31; an outlet at the bottom of the reboiler 31 is connected with a lean and rich absorption liquid heat exchanger 25 through a lean liquid delivery pump 33, the lean and rich absorption liquid heat exchanger 25 is connected with a lean absorption liquid cooler 35, an absorption liquid storage and configuration device 34 is connected with an inlet of the lean absorption liquid cooler 35, an outlet of the lean absorption liquid cooler 35 is divided into two paths, one path is connected with a filtering and purifying device 36 and then converged with the other path, the two paths are divided into two paths again, one path is connected with an inlet of the second infinitesimal generation device 12 through a lean liquid booster pump 37, and the other path is connected with a filler column 24 of the flash tank 21.
As shown in fig. 2, a raw material gas 1 enters a gravity separator 2 to separate large-particle liquid droplets and solid impurities, then enters a raw material gas filtering separator 3 to remove small solid particles and liquid droplets possibly carried in the gas to obtain pretreated natural gas 4, and then enters a first infinitesimal generator 6 together with a circulating absorption liquid (circulating rich liquid) 5 from a first rich liquid circulating pump to generate a first infinitesimal dispersion system 7 (the size is 1-800 μm, and the optimal value is 50-350 μm) with a micrometer scale. And carrying out desulfurization and decarburization reaction in the first infinitesimal dispersion system, then, carrying out gas-liquid separation in a first gas-liquid separator 8, discharging first crude decarburization natural gas 9 from a top gas-phase outlet, and taking a liquid phase in the separator as a first rich absorption liquid. The first crude decarbonized natural gas 9 and the lean absorption liquid 12 from the lean liquid booster pump 37 are dispersed into a second infinitesimal dispersion system 14 (with the size of 1-800 μm and the optimal value of 50-350 μm) with micron scale in a second infinitesimal generation device 13, and the desulfurization and decarbonization reaction of the absorption liquid simultaneously occurs. Then, the second micro-element dispersion system 14 is separated into a gas-liquid two-phase in a second gas-liquid separator 15, the gas phase is the fine desulfurized and decarbonized natural gas 16, the gas phase enters a subsequent purification process, the liquid phase is a second rich absorption liquid 17, the second rich absorption liquid is conveyed to a first gas-liquid separator 8 through a second rich liquid circulating pump 18, and the second rich absorption liquid is mixed with the rich liquid separated from the first micro-element dispersion system to form a first rich absorption liquid, and the first rich absorption liquid is divided into two streams 10 and 11 to flow out. The first rich absorbent liquid 10 is sent to the first infinitesimal generation device 6 by a first rich liquid circulation pump 19. The first rich absorption liquid 11 is depressurized by a turbine 20 and enters a flash evaporation tank 21 for flash evaporation, and the flash evaporation gas 22 and the lean absorption liquid 23 are in countercurrent contact in a packed column 24 to remove hydrogen sulfide and then are discharged from a device and enter a fuel gas system. The rich absorption liquid flowing out of the liquid phase outlet of the flash tank enters a lean absorption liquid heat exchanger 25, exchanges heat with the regenerated lean absorption liquid, then is heated, and enters an inlet at the middle upper part of the regeneration tower 26. An outlet at the top of the regeneration tower is sequentially connected with a tower top condenser 27 and a regeneration tower reflux tank 28, acid gas 29 is discharged from a gas phase outlet at the top of the regeneration tower reflux tank, reflux liquid is discharged from a liquid phase outlet at the bottom of the regeneration tower reflux tank 28, and the reflux liquid is conveyed back to the top of the regeneration tower through a regeneration tower reflux pump 30; the liquid phase outlet at the bottom of the regeneration tower is connected with a reboiler 31 at the bottom of the regeneration tower, saturated steam 32 is used as a heat source, the absorption liquid is heated in the reboiler 31 and partially gasified, the absorption liquid returns to the bottom of the regeneration tower, the other part of the liquid is discharged from the outlet at the bottom of the reboiler and is used as regenerated lean absorption liquid, the regenerated lean absorption liquid is conveyed to enter a lean and rich absorption liquid heat exchanger 25 through a lean liquid conveying pump 33 to be cooled, the lean absorption liquid is merged with supplemented absorption liquid from an absorption liquid storage and configuration unit 34 and then enters a lean absorption liquid cooler 35 to be further cooled, the cooled lean absorption liquid is divided into two parts, one part of the lean absorption liquid enters a filtering and purifying unit 36 to be re-merged with the other part of the lean absorption liquid which is not filtered and purified, the merged lean absorption liquid is divided into a small part 23 to enter a filler column 24 in a flash tank, and the rest part of the lean absorption liquid is pressurized through a lean liquid booster pump 37 and then enters a liquid phase inlet of a second infinitesimal generation device 13, so that the cyclic utilization of the absorption liquid is realized.
The desulfurization and decarburization effects of the present invention will be described in detail below by taking FIGS. 1 and 2 as examples, but the present invention is not limited to the following examples.
Example 1 desulfurization and decarbonization of Natural gas
To verify the effectiveness of the present invention, the process flow shown in FIG. 1 was used. The first and second infinitesimal generation devices used in this embodiment are swirl-type microbubble generation devices (the structure design of the axial swirl-type microbubble generator and the numerical simulation of the structure in DOI:10.12034/j.issn.1009-606X.217413 are adopted in the document, wherein the microporous plate used for gas injection has an average aperture of 50 micrometers, the liquid phase inlet diameter is 10cm, the inner diameter of the venturi throat is 3cm, and 4 sets are connected in parallel). The first gas-liquid separator and the second gas-liquid separator adopted in the present embodiment are centrifugal gas-liquid separators. The absorption liquid used in this example was an aqueous solution of the MDEA single component. The properties of the feed gas are shown in table 1, the feed gas with the flow rate of 10320kmol/h and the pressure of 9.1MPa passes through a gravity separator and a feed gas filtering separator to remove solid particles and liquid drops in the gas, and then enters a first infinitesimal generating device with circulating absorption liquid (the flow rate is 7256kmol/h and the temperature is 51 ℃) from a pregnant solution circulating pump to generate a first infinitesimal dispersion system (the average size is 350 μm and the operating pressure is 9.1 MPa) with the micron scale. Desulfurizing and decarbonizing in the first micro-disperse system, gas-liquid separation in the first gas-liquid separator, anda crude decarbonized natural gas is discharged from the top gas phase outlet, and a first rich absorption liquid is discharged from the bottom liquid phase outlet. The first crude decarbonized natural gas and the lean absorption liquid (the flow rate is 7000kmol/h, the MDEA concentration is 50wt%, and the temperature is 35 ℃) from a lean liquid booster pump are dispersed into a second micro-element dispersion system (the average size is 350 mu m, and the operating pressure is 9.0 MPa) in a micron scale in a second micro-element generation device, and the desulfurization and decarbonization reaction of the absorption liquid are carried out simultaneously. Then, the second infinitesimal dispersion system is separated into a gas phase and a liquid phase in a second gas-liquid separator, and the gas phase is the refined desulfurized and decarbonized natural gas (H) 2 The S content was 5.30ppm and CO was present 2 The content is 1.84mol percent), enters a subsequent purification process, and the liquid phase is a second rich absorption liquid which is conveyed to a first infinitesimal generating device through a rich liquid circulating pump. The first rich absorption liquid from the liquid phase outlet of the first gas-liquid separator is depressurized by a turbine and then enters a flash evaporation tank for flash evaporation, and the flash evaporation gas and the lean absorption liquid are in countercurrent contact in a packed column to remove hydrogen sulfide and then are discharged from a device to enter a fuel gas system. And the rich absorption liquid flowing out of the liquid phase outlet of the flash tank enters a lean absorption liquid heat exchanger, exchanges heat with the regenerated lean absorption liquid, then is heated, and enters an inlet at the middle upper part of the regeneration tower. An outlet at the top of the regeneration tower is sequentially connected with a tower top condenser and a regeneration tower reflux tank, acid gas is discharged from a gas phase outlet at the top of the regeneration tower reflux tank, reflux liquid is discharged from a liquid phase outlet at the bottom of the regeneration tower reflux tank, and the reflux liquid is conveyed back to the top of the regeneration tower through a regeneration tower reflux pump; the liquid phase outlet at the bottom of the regeneration tower is connected with a reboiler at the bottom of the regeneration tower, saturated steam is used as a heat source, the absorption liquid is heated in the reboiler and partially gasified, the absorption liquid returns to the bottom of the regeneration tower, the other part of the liquid is discharged from the outlet at the bottom of the reboiler and is used as regenerated lean absorption liquid, the regenerated lean absorption liquid is conveyed to a lean rich absorption liquid heat exchanger through a lean liquid conveying pump to be cooled, the lean absorption liquid is merged with supplementary absorption liquid from an absorption liquid storage and configuration unit and then enters a lean absorption liquid cooler to be further cooled, the cooled lean absorption liquid is divided into two parts, one part of the cooled lean absorption liquid enters a filtering and purifying unit to be re-merged with the other part of the lean absorption liquid which is not filtered and purified, the merged lean absorption liquid is divided into a small part of the lean absorption liquid and enters a filler column in a flash tank, and the rest part of the lean absorption liquid is pressurized by a booster pump and then enters a liquid phase inlet of a second infinitesimal generator, so that the cyclic utilization of the absorption liquid is realized.
In comparison, the conventional alcohol amine process is adopted, and the process flow differs from the process in that a first acid gas absorption system and a second acid gas absorption system (namely a first infinitesimal generator, a first gas-liquid separator, a second infinitesimal generator and a second gas-liquid separator) are replaced by a conventional absorption tower comprising 8 tower plates, the properties and the flow rate of the raw material gas for treatment are shown in table 1, and the adopted absorption liquid is an MDEA solution (the flow rate is 7000kmol/h, the concentration of MDEA is 50wt%, and the temperature is 35 ℃) with the same concentration, temperature and flow rate as the MDEA solution in the embodiment
The desulfurization effect, equipment size and conventional absorber process are compared in table 2. In table 2, the volume of the absorption apparatus according to the embodiment of the present invention is the total volume of the first acidic gas absorption system and the second acidic gas absorption system (i.e., the first infinitesimal generation device, the first gas-liquid separator, the second infinitesimal generation device, and the second gas-liquid separator).
As can be seen from Table 2, under the same operation conditions, the volume of the absorption equipment is obviously reduced and the decarburization rate is obviously improved on the basis of being similar to the conventional alcohol amine absorption process. Although the first acid gas absorption system and the second acid gas absorption system adopt 4 devices (namely, the first infinitesimal generation device, the first gas-liquid separator, the second infinitesimal generation device and the second gas-liquid separator), the volumes are small, and the arrangement is flexible.
TABLE 1 Properties of the feed gases
Figure GDA0003518458040000111
TABLE 2 desulfurization Effect, equipment size and energy consumption
Figure GDA0003518458040000112
Example 2 desulfurization and decarbonization of Natural gas
To verify the effectiveness of the present invention, the process flow shown in FIG. 1 was used. The first infinitesimal generating device and the second infinitesimal generating device adopted by the embodiment are rotational flow type micro-airBubble generating device (adopting the structure design of the axial cyclone type microbubble generator and numerical simulation of the structure in DOI:10.12034/j.issn.1009-606X.217413, wherein the average aperture of a micropore plate used for gas injection is 50 microns, the diameter of a liquid phase inlet is 10cm, the inner diameter of a Venturi throat is 3cm, and 4 sets are connected in parallel). The first gas-liquid separator and the second gas-liquid separator adopted in the embodiment are centrifugal gas-liquid separators. The absorption liquid used in this example was an aqueous solution of the MDEA single component. The properties of the raw material gas are shown in table 1, the raw material gas with the flow rate of 10320kmol/h and the pressure of 9.1MPa passes through a gravity separator and a raw material gas filtering separator to remove solid particles and liquid drops in the gas, and then enters a first infinitesimal generating device together with a circulating absorption liquid (the flow rate is 7256kmol/h and the temperature is 51 ℃) from a pregnant solution circulating pump to generate a first infinitesimal dispersion system (the average size is 200 μm and the operating pressure is 9.1 MPa) with the micron scale. And carrying out desulfurization and decarburization reaction in the first infinitesimal dispersion system, then, entering a first gas-liquid separator for gas-liquid separation, discharging first coarse decarburized natural gas from a top gas-phase outlet, and taking a liquid phase in the separator as a first rich absorption liquid. The first crude decarbonized natural gas and the lean absorption liquid from the lean liquid booster pump are dispersed into a second micro-element dispersion system (the average size is 350 mu m, the operating pressure is 9.0 MPa) in a micron scale in a second micro-element generation device, and the desulfurization and decarbonization reaction of the absorption liquid simultaneously occurs. Then, the second infinitesimal dispersion system is separated into a gas phase and a liquid phase in a second gas-liquid separator, and the gas phase is the refined desulfurized and decarbonized natural gas (H) 2 The S content was 5.25ppm, CO was present 2 The content is 1.23 mol%), the mixture enters a subsequent purification process, a liquid phase is a second rich absorption liquid, the second rich absorption liquid is conveyed to a first gas-liquid separator through a second rich liquid circulating pump and is mixed with rich liquid separated from a first infinitesimal dispersion system to form a first rich absorption liquid, the first rich absorption liquid is divided into two streams to flow out, one stream is conveyed to a first infinitesimal generating device through a first rich liquid circulating pump, the other stream of the first rich absorption liquid enters a flash evaporation tank for flash evaporation after being subjected to pressure reduction by a turbine, and the flash evaporation gas and the lean absorption liquid are in countercurrent contact in a packed column to remove hydrogen sulfide and then enter an exhaust device into a fuel gas system. And the rich absorption liquid flowing out of the liquid phase outlet of the flash tank enters a lean and rich absorption liquid heat exchanger, exchanges heat with the regenerated lean absorption liquid, then is heated, and enters an inlet at the middle upper part of the regeneration tower.An outlet at the top of the regeneration tower is sequentially connected with a tower top condenser and a regeneration tower reflux tank, acid gas is discharged from a gas phase outlet at the top of the regeneration tower reflux tank, reflux liquid is discharged from a liquid phase outlet at the bottom of the regeneration tower reflux tank, and the reflux liquid is conveyed back to the top of the regeneration tower through a regeneration tower reflux pump; the liquid phase outlet at the bottom of the regeneration tower is connected with a reboiler at the bottom of the regeneration tower, saturated steam is used as a heat source, the absorption liquid is heated in the reboiler and partially gasified, the absorption liquid returns to the bottom of the regeneration tower, the other part of the liquid is discharged from the outlet at the bottom of the reboiler and is used as regenerated lean absorption liquid, the regenerated lean absorption liquid is conveyed to a lean rich absorption liquid heat exchanger through a lean liquid conveying pump to be cooled, the lean absorption liquid is merged with supplementary absorption liquid from an absorption liquid storage and configuration unit and then enters a lean absorption liquid cooler to be further cooled, the cooled lean absorption liquid is divided into two parts, one part of the cooled lean absorption liquid enters a filtering and purifying unit to be re-merged with the other part of the lean absorption liquid which is not filtered and purified, the merged lean absorption liquid is divided into a small part of the lean absorption liquid and enters a filler column in a flash tank, and the rest part of the lean absorption liquid is pressurized by a booster pump and then enters a liquid phase inlet of a second infinitesimal generator, so that the cyclic utilization of the absorption liquid is realized.
In comparison, the conventional alcohol amine process is adopted, and the process flow differs from the process in that a first acid gas absorption system and a second acid gas absorption system (namely a first infinitesimal generator, a first gas-liquid separator, a second infinitesimal generator and a second gas-liquid separator) are replaced by a conventional absorption tower comprising 8 tower plates, the properties and the flow rate of the raw material gas for treatment are shown in table 1, and the adopted absorption liquid is an MDEA solution (the flow rate is 7000kmol/h, the concentration of MDEA is 50wt%, and the temperature is 35 ℃) with the same concentration, temperature and flow rate as the MDEA solution in the embodiment
The desulfurization effect, equipment size and conventional absorber process are compared in table 3. In table 3, the volume of the absorption apparatus according to the embodiment of the present invention is the total volume of the first acidic gas absorption system and the second acidic gas absorption system (i.e., the first infinitesimal generation device, the first gas-liquid separator, the second infinitesimal generation device, and the second gas-liquid separator).
As can be seen from Table 3, under the same operation conditions, the volume of the absorption equipment is obviously reduced and the decarburization rate is obviously improved on the basis of being similar to the conventional alcohol amine absorption process. Although the first acid gas absorption system and the second acid gas absorption system adopt 4 devices (namely the first infinitesimal generation device, the first gas-liquid separator, the second infinitesimal generation device and the second gas-liquid separator), the volumes are small, and the arrangement is flexible.
TABLE 3 desulfurization Effect, equipment size and energy consumption
Figure GDA0003518458040000131

Claims (8)

1. A natural gas desulfurization and decarburization system comprises a raw material gas pretreatment system, a first acid gas absorption system, a second acid gas absorption system, a flash evaporation system and an absorption liquid regeneration system;
the raw material gas pretreatment system comprises a raw material gas gravity separator and a raw material gas filtering separator; the outlet of the feed gas gravity separator is connected with the inlet of the feed gas filtering separator;
the first acid gas absorption system comprises a first infinitesimal generation device and a first gas-liquid separator; the outlet of the feed gas filtering separator is connected with the gas phase inlet of the first infinitesimal generation device; the outlet of the first infinitesimal generation device is connected with the inlet of the first gas-liquid separator;
the second acid gas absorption system comprises a second infinitesimal generation device and a second gas-liquid separator; the gas-phase outlet of the first gas-liquid separator is connected with the gas-phase inlet of the second infinitesimal generating device; the outlet of the second micro element generating device is connected with the inlet of the second gas-liquid separator;
the first infinitesimal generating device and the second infinitesimal generating device are infinitesimal generating devices capable of cutting a gas-liquid two-phase system into micron-scale infinitesimal generating devices;
the micro element generating device is one or a combination of series connection and/or parallel connection of a plurality of micro-porous membranes, venturi type micro-bubble generating devices, ultrasonic cavitation devices, hydrodynamic cavitation type micro-bubble generating devices, centrifugal type micro-bubble generating devices, jet type micro-bubble generating devices and rotational flow type micro-bubble generating devices;
the flash system comprises a pressure reduction device and a flash tank; the pressure reduction device is a turbine or a pressure reduction valve;
the liquid phase outlets of the first gas-liquid separator and the second gas-liquid separator are connected by 1) or 2) as follows:
1) The liquid phase outlet of the first gas-liquid separator is connected with the flash tank through the pressure reduction device; a liquid phase outlet of the second gas-liquid separator is connected with an inlet of the first infinitesimal generation device through a rich liquid circulating pump;
2) The liquid phase outlet of the first gas-liquid separator is divided into two paths, one path is connected with the flash tank through the pressure reduction device, and the other path is connected with the liquid phase inlet of the first infinitesimal generation device through a rich liquid circulating pump; the liquid phase outlet of the second gas-liquid separator is connected with the inlet of the first gas-liquid separator through a rich liquid circulating pump;
the absorption liquid regeneration system comprises a regeneration tower, a tower top condenser, an absorption liquid storage and configuration device, a regeneration tower reflux tank and a reboiler; the flash tank is connected with an inlet at the middle upper part of the regeneration tower through a lean-rich absorption liquid heat exchanger; the top outlet of the regeneration tower is sequentially connected with the tower top condenser and the regeneration tower reflux tank; a liquid phase outlet at the bottom of the regeneration tower reflux tank is connected with an inlet at the middle upper part of the regeneration tower through a regeneration tower reflux pump; the liquid phase outlet at the bottom of the regeneration tower is connected with the reboiler; the bottom outlet of the reboiler is connected with the lean and rich absorption liquid heat exchanger through a lean liquid delivery pump, the lean and rich absorption liquid heat exchanger is connected with a lean absorption liquid cooler, the absorption liquid storage and configuration device is connected with the inlet of the lean absorption liquid cooler, the outlet of the lean absorption liquid cooler is divided into two paths, one path is connected with a filtering and purifying device and then converged with the other path, and the two paths are connected with the inlet of the second infinitesimal generation device through a lean liquid booster pump.
2. The system of claim 1, wherein: the first gas-liquid separator and the second gas-liquid separator are gas-liquid separators capable of separating gas bubbles of 30 μm or more from a liquid phase;
the gas-liquid separator is one or a combination of a centrifugal separator, a gravity separator, a baffling separator, a filler separator, a wire mesh separator and a microporous filtering separator which are connected in series and/or in parallel.
3. The system according to claim 1 or 2, characterized in that: and the two paths of the outlet of the lean absorption liquid cooler are converged and then divided into two paths again, one path is connected with the inlet of the second gas-liquid separator through the lean liquid booster pump, and the other path is connected with the packing column of the flash tank.
4. A natural gas desulfurization and decarburization method comprises the following steps:
(1) Pretreating the natural gas feed gas to remove solid particles and liquid drops in the natural gas feed gas;
the pretreated natural gas and the circulating rich solution enter a first infinitesimal generating device to be dispersed into a first infinitesimal dispersion system with micron scale, acid gas in the first infinitesimal dispersion system and absorption liquid are subjected to absorption reaction, and the reacted first infinitesimal dispersion system enters a first gas-liquid separator to be separated into first coarse decarburized natural gas and first rich absorption liquid;
the first coarse decarbonized natural gas and the poor absorption liquid enter a second infinitesimal generating device to be dispersed into a second infinitesimal dispersion system with a micron scale, acid gas in the second infinitesimal dispersion system and the absorption liquid are subjected to absorption reaction, and the reacted second infinitesimal dispersion system enters a second gas-liquid separator to be separated into fine decarbonized natural gas and a second rich absorption liquid;
the first infinitesimal generating device and the second infinitesimal generating device are infinitesimal generating devices capable of cutting a gas-liquid two-phase system into micron scales;
the micro element generating device is one or a combination of series connection and/or parallel connection of a microporous membrane, a Venturi type micro bubble generating device, an ultrasonic cavitation device, a hydrodynamic cavitation type micro bubble generating device, a centrifugal type micro bubble generating device, a jet type micro bubble generating device and a rotational flow type micro bubble generating device;
(2) The first rich absorption liquid and the second rich absorption liquid are conveyed by the following 1) or 2);
1) The first rich absorption liquid is depressurized by a turbine or a pressure reducing valve and then enters a flash tank for flash evaporation; the second rich absorption liquid is conveyed to the first infinitesimal generation device by a rich liquid circulating pump to be used as the circulating rich liquid in the step (1);
2) The first rich absorption liquid is divided into two parts, one part is conveyed to the first infinitesimal generation device by a rich liquid circulating pump to be used as the circulating rich liquid in the step (1), and the other part enters a flash evaporation tank for flash evaporation after being subjected to pressure reduction by a turbine or a pressure reducing valve; the second rich absorption liquid is conveyed to the first gas-liquid separator through a rich liquid circulating pump;
(3) Hydrogen sulfide in flash gas flowing out of the top of the flash tank is removed, the flash gas enters a fuel gas system, and rich absorption liquid flowing out of a liquid phase outlet of the flash tank enters a lean and rich absorption liquid heat exchanger;
the rich absorption liquid flowing out of the liquid phase outlet of the flash tank exchanges heat with the regenerated lean absorption liquid, the temperature is raised, the rich absorption liquid enters the upper inlet of the regeneration tower, the acid gas in the natural gas enriched in the absorption liquid is desorbed and discharged from the top of the regeneration tower, the natural gas is condensed by a condenser at the top of the regeneration tower and enters a reflux tank of the regeneration tower, the separated acid gas is discharged from a gas phase outlet at the top of the reflux tank of the regeneration tower, the separated reflux liquid is discharged from a liquid phase outlet at the bottom of the reflux tank of the regeneration tower and is sent back to the top of the regeneration tower through a reflux pump of the regeneration tower; liquid flowing out of a liquid phase outlet at the bottom of the regeneration tower enters a reboiler at the bottom of the regeneration tower, one part of the liquid is heated in the reboiler, the part of the liquid is gasified and returned to the bottom of the regeneration tower, and the other part of the liquid is discharged from an outlet at the bottom of the reboiler to serve as the regenerated lean absorption liquid to enter the lean absorption liquid heat exchanger;
and (2) exchanging heat between the regenerated lean absorption liquid and rich absorption liquid flowing out of a liquid phase outlet of the flash tank, cooling, merging with supplementary absorption liquid from an absorption liquid storage and configuration unit, then feeding into a lean absorption liquid cooler for further cooling, dividing into two parts after cooling, feeding one part into a filtering and purifying unit for removing impurities, then re-merging with the other part, and conveying to the second infinitesimal generation device by a lean liquid booster pump to serve as the lean absorption liquid in the step (1).
5. The method of claim 4, wherein: the size of the first infinitesimal dispersion system and the second infinitesimal dispersion system is 1-800 mu m.
6. The method according to claim 4 or 5, characterized in that: the operating pressure of the first infinitesimal generating device and the second infinitesimal generating device is 3-15 MPa, the operating temperature is 30-80 ℃, and the gas-liquid ratio is 200-5000 Nm 3 /m 3 。
7. The method of claim 6, wherein: the gas-liquid ratio is 200-1000 Nm 3 /m 3 。
8. The method according to claim 4 or 5, characterized in that: the content of hydrogen sulfide in the natural gas feed gas is lower than 0.8mol%, and the content of carbon dioxide is lower than 8mol%.
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