Disclosure of Invention
The invention aims to provide an efficient and compact natural gas glycol dehydration system and method.
The purpose of the invention is realized by the following technical scheme:
the invention relates to a high-efficiency compact natural gas glycol dehydration system, which comprises a filtering separator underflow valve 1, a filtering separator 2, a tubular gas-liquid contact absorber 3, a triethylene glycol condenser 4, a glycol pump 5, a natural gas/lean glycol heat exchanger 6, a demister 7, a demister underflow valve 8, a lean glycol storage tank 9, a lean/rich glycol heat exchanger 10, a tubular gas-liquid contact desorber 11, a condenser 12, a three-phase separator 13, a stripping agent pump 14, a first stop valve 15, a stripping agent injection stop valve 16, a coalescer 17, a coalescer drain valve 18, a first stripping agent dryer 19, a second stripping agent dryer 20, a stripping agent heater 21, a reboiler 22, a glycol filter 23, a flash tank 24 and a second stop valve 25 which are connected through pipelines;
the bottom outlet of the filter separator 2 is connected with a filter separator underflow valve 1, the outlet of the filter separator underflow valve 1 is connected with a downstream sewage disposal system, and the top outlet of the filter separator 2 is connected with a gas phase inlet of a tubular gas-liquid contact absorber 3;
a gas phase outlet of the tubular gas-liquid contact absorber 3 is connected with a natural gas inlet of a natural gas/lean glycol heat exchanger 6, a natural gas outlet of the natural gas/lean glycol heat exchanger 6 is connected with an inlet of a demister 7, a gas phase outlet at the upper part of the demister 7 is connected with a downstream natural gas treatment section, a liquid phase outlet at the lower part of the demister 7 is connected with an inlet of a demister underflow valve 8, and an outlet of the demister underflow valve 8 is connected with a flash tank 24;
a liquid phase outlet at the lower part of the tubular gas-liquid contact absorber 3 is connected with a second stop valve 25, the second stop valve 25 is connected with a flash drum 24, a gas phase outlet at the upper part of the flash drum 24 is connected with a tail gas treatment system, a liquid phase outlet at the bottom of the flash drum 24 is connected with an inlet of a glycol filter 23, an outlet of the glycol filter 23 is connected with a glycol-rich inlet of the lean/glycol-rich heat exchanger 10, a glycol-rich outlet of the lean/glycol-rich heat exchanger 10 is connected with a liquid phase inlet of the tubular gas-liquid contact desorber 11, and a liquid phase outlet of the tubular gas-liquid contact desorber 11 is connected with an inlet at the upper part of the reboiler 22;
a gas phase outlet of the tubular gas-liquid contact desorber 11 is connected with an inlet of a condenser 12, an outlet of the condenser 12 is connected with an inlet of a three-phase separator 13, a non-condensable gas outlet of the three-phase separator 13 leads to tail gas treatment, and a water outlet is arranged at the lower end of the three-phase separator 13;
the outlet of the stripping agent of the three-phase separator 13 is connected with the inlet of a stripping agent pump 14, the outlet of the stripping agent pump 14 is connected with the inlet of a stripping agent coalescer 17, the outlet of the stripping agent coalescer 17 is connected with the inlet of a first stripping agent dryer 19, the upper part of the stripping agent coalescer 17 is provided with a stripping agent feeding port and is connected with a stripping agent injection stop valve 16, the stripping agent is fed through the inlet of the stripping agent injection stop valve 16, and the lower part of the stripping agent coalescer 17 is provided with a water drain port and is connected with a coalescer drain valve 18;
the first stripping agent dryer 19, the second stripping agent dryer 20 and the stripping agent heater 21 are sequentially connected, and an outlet of the stripping agent heater 21 is connected with a stripping agent inlet at the lower part of the reboiler 22 to realize circulation of the stripping agent;
the gas phase outlet of the reboiler 22 is connected with the gas phase inlet of the tubular gas-liquid contact desorber 11, the liquid phase outlet of the reboiler 22 is connected with the lean glycol inlet of the lean/rich glycol heat exchanger 6, the lean glycol outlet of the lean/rich glycol heat exchanger 6 is connected with the inlet of the lean glycol storage tank 9, the bottom outlet of the lean glycol storage tank 9 is connected with the lean glycol inlet of the natural gas/lean glycol heat exchanger 6, the lean glycol outlet of the natural gas/lean glycol heat exchanger 9 is connected with the inlet of the glycol pump 5, the outlet of the glycol pump 5 is connected with the inlet of the triethylene glycol condenser 4, and the outlet of the triethylene glycol condenser 4 is connected with the liquid phase inlet of the tubular gas-liquid contact absorber 3, so that the circulation of the triethylene glycol is realized.
The tubular gas-liquid contact absorber is characterized in that the atomizing part is a tubular atomizer or a wire mesh packing, and the gas-liquid separation part is a demisting tubular gas-liquid separator. The tubular gas-liquid contact desorber atomization mixing component is a tubular atomizer or a wire mesh packing, and the gas-liquid separation component is a tubular gas-liquid separator.
The method for dehydrating the natural gas glycol by using the efficient compact natural gas glycol dehydration system comprises the following steps:
(1) allowing natural gas with pressure of 2-20MPa to enter a filter separator, removing free liquid water and solid impurities, and discharging from an outlet of the filter separator;
(2) allowing the natural gas discharged in the step (1) to enter a tubular gas-liquid contact absorber, enabling the natural gas to be in parallel flow contact with micron-sized atomized triethylene glycol liquid drops in the tubular gas-liquid contact absorber, discharging the water of the raw material natural gas out of the tubular gas-liquid contact absorber after being absorbed, allowing the water to enter a demister after being cooled by a natural gas/lean glycol heat exchanger, further removing the tiny triethylene glycol liquid drops carried by the natural gas, and discharging the demisted and purified dry natural gas through a demister gas phase outlet to enter a downstream working section;
(3) discharging the rich triethylene glycol absorbing the moisture in the step (2) out of a tubular gas-liquid contact absorber, exchanging heat with triethylene glycol lean solution, then entering a flash tank, flashing the rich triethylene glycol in the flash tank, filtering the rich triethylene glycol through a filter, and then entering a lean/rich ethylene glycol heat exchanger to exchange heat with the lean triethylene glycol;
(4) in the step (3), the triethylene glycol-rich gas enters a tubular gas-liquid contact desorber after heat exchange through a lean/rich glycol heat exchanger, the triethylene glycol-rich gas is atomized into micron-sized liquid drops in the tubular gas-liquid contact desorber and is in countercurrent contact with a stripping agent gasified by a reboiler, and water in the triethylene glycol-rich gas migrates to a gas phase; on one hand, the stripping agent and water in the triethylene glycol form an azeotrope, so that the water is transferred to a gas phase in the form of the azeotrope, on the other hand, the gasified stripping agent can atomize the triethylene glycol into micron-sized liquid drops to increase the gas-liquid mass transfer area, and the triethylene glycol liquid drops and the gasified stripping agent turbulently transfer mass in the same direction, so that the water is promoted to migrate to the gas phase; the desorbed triethylene glycol is discharged from a liquid phase outlet of the tubular gas-liquid contact desorber and enters a reboiler, and the stripping agent is discharged from a gas phase outlet of the tubular gas-liquid contact desorber;
(5) the stripping agent discharged from the gas phase outlet of the tubular gas-liquid contact desorber in the step (4) enters a stripping agent condenser, and is discharged out of the stripping agent condenser after being condensed into a liquid state;
(6) the stripping agent discharged from the stripping agent condenser in the step (5) enters a three-phase separator, water is separated from the stripping agent, the non-condensable gas is led to a tail gas treatment working section, triethylene glycol and water are discharged out of the system, and the stripping agent enters a stripping agent coalescer for coalescence;
(7) in the step (6), the stripping agent is coalesced by a coalescer and then emulsified water in the stripping agent is separated, the coalesced and removed water is discharged out of the system through a bottom outlet, the stripping agent lost in the recovery process of the stripping agent is supplemented through an inlet at the top of the coalescer, and the stripping agent with the emulsified water removed enters a first stripping agent dryer;
(8) the stripping agent entering the first stripping agent dryer in the step (7) sequentially enters the second stripping agent dryer, trace moisture in the stripping agent is further removed through drying, then the stripping agent enters a reboiler, the stripping agent forms an azeotrope with water in triethylene glycol discharged from a liquid phase outlet of the tubular gas-liquid contact desorber in the step (4) in the reboiler, and the azeotrope is gasified, so that the recycling of the stripping agent is realized; the triethylene glycol is discharged from a liquid phase outlet of the reboiler after being further regenerated;
(9) the lean triethylene glycol discharged from the liquid phase outlet of the reboiler in the step (8) enters a lean ethylene glycol storage tank, and a stable liquid level is formed in the storage tank;
(10) and (4) carrying out heat exchange and cooling on the triethylene glycol lean solution in the lean ethylene glycol storage tank in the step (9) by a natural gas/lean ethylene glycol heat exchanger, conveying the triethylene glycol lean solution to a triethylene glycol condenser by a glycol pump, condensing the triethylene glycol condenser, and then feeding the triethylene glycol lean solution into a tubular gas-liquid contact absorber to realize circulation of triethylene glycol.
According to the technical scheme provided by the invention, the efficient and compact natural gas glycol dehydration system and method provided by the embodiment of the invention adopt the tubular gas-liquid contact absorber to replace a rectification column of a traditional glycol regeneration system, so that the compactness of the natural gas glycol dehydration system is further enhanced, and the flexibility of the installation and arrangement of a dehydration device is improved. The whole device has light weight, small occupied area, low glycol circulation amount and flexible installation and arrangement, and the dehydrated natural gas water dew point meets the requirements of offshore platform production and long-distance gathering and transportation indexes. The problem that the existing natural gas triethylene glycol dehydration process technology adopting the traditional tower type mass transfer device is applied to an offshore platform is solved.
Detailed Description
The embodiments of the present invention will be described in further detail below. Details which are not described in detail in the embodiments of the invention belong to the prior art which is known to the person skilled in the art.
The high-efficiency compact natural gas glycol dehydration system of the invention has the preferred embodiment as shown in fig. 1 to 3:
the device comprises a filtering separator underflow valve 1, a filtering separator 2, a tubular gas-liquid contact absorber 3, a triethylene glycol condenser 4, a glycol pump 5, a natural gas/lean glycol heat exchanger 6, a demister 7, a demister underflow valve 8, a lean glycol storage tank 9, a lean/rich glycol heat exchanger 10, a tubular gas-liquid contact desorber 11, a condenser 12, a three-phase separator 13, a stripping agent pump 14, a first stop valve 15, a stripping agent injection stop valve 16, a coalescer 17, a coalescer drain valve 18, a first stripping agent dryer 19, a second stripping agent dryer 20, a stripping agent heater 21, a reboiler 22, a glycol filter 23, a flash tank 24 and a second stop valve 25 which are connected through pipelines;
the bottom outlet of the filter separator 2 is connected with a filter separator underflow valve 1, the outlet of the filter separator underflow valve 1 is connected with a downstream sewage disposal system, and the top outlet of the filter separator 2 is connected with a gas phase inlet of a tubular gas-liquid contact absorber 3;
a gas phase outlet of the tubular gas-liquid contact absorber 3 is connected with a natural gas inlet of a natural gas/lean glycol heat exchanger 6, a natural gas outlet of the natural gas/lean glycol heat exchanger 6 is connected with an inlet of a demister 7, a gas phase outlet at the upper part of the demister 7 is connected with a downstream natural gas treatment section, a liquid phase outlet at the lower part of the demister 7 is connected with an inlet of a demister underflow valve 8, and an outlet of the demister underflow valve 8 is connected with a flash tank 24;
a liquid phase outlet at the lower part of the tubular gas-liquid contact absorber 3 is connected with a second stop valve 25, the second stop valve 25 is connected with a flash drum 24, a gas phase outlet at the upper part of the flash drum 24 is connected with a tail gas treatment system, a liquid phase outlet at the bottom of the flash drum 24 is connected with an inlet of a glycol filter 23, an outlet of the glycol filter 23 is connected with a glycol-rich inlet of the lean/glycol-rich heat exchanger 10, a glycol-rich outlet of the lean/glycol-rich heat exchanger 10 is connected with a liquid phase inlet of the tubular gas-liquid contact desorber 11, and a liquid phase outlet of the tubular gas-liquid contact desorber 11 is connected with an inlet at the upper part of the reboiler 22;
a gas phase outlet of the tubular gas-liquid contact desorber 11 is connected with an inlet of a condenser 12, an outlet of the condenser 12 is connected with an inlet of a three-phase separator 13, a non-condensable gas outlet of the three-phase separator 13 leads to tail gas treatment, and a water outlet is arranged at the lower end of the three-phase separator 13;
the outlet of the stripping agent of the three-phase separator 13 is connected with the inlet of a stripping agent pump 14, the outlet of the stripping agent pump 14 is connected with the inlet of a stripping agent coalescer 17, the outlet of the stripping agent coalescer 17 is connected with the inlet of a first stripping agent dryer 19, the upper part of the stripping agent coalescer 17 is provided with a stripping agent feeding port and is connected with a stripping agent injection stop valve 16, the stripping agent is fed through the inlet of the stripping agent injection stop valve 16, and the lower part of the stripping agent coalescer 17 is provided with a water drain port and is connected with a coalescer drain valve 18;
the first stripping agent dryer 19, the second stripping agent dryer 20 and the stripping agent heater 21 are sequentially connected, and an outlet of the stripping agent heater 21 is connected with a stripping agent inlet at the lower part of the reboiler 22 to realize circulation of the stripping agent;
the gas phase outlet of the reboiler 22 is connected with the gas phase inlet of the tubular gas-liquid contact desorber 11, the liquid phase outlet of the reboiler 22 is connected with the lean glycol inlet of the lean/rich glycol heat exchanger 6, the lean glycol outlet of the lean/rich glycol heat exchanger 6 is connected with the inlet of the lean glycol storage tank 9, the bottom outlet of the lean glycol storage tank 9 is connected with the lean glycol inlet of the natural gas/lean glycol heat exchanger 6, the lean glycol outlet of the natural gas/lean glycol heat exchanger 9 is connected with the inlet of the glycol pump 5, the outlet of the glycol pump 5 is connected with the inlet of the triethylene glycol condenser 4, and the outlet of the triethylene glycol condenser 4 is connected with the liquid phase inlet of the tubular gas-liquid contact absorber 3, so that the circulation of the triethylene glycol is realized.
The tubular gas-liquid contact absorber is characterized in that the atomizing part is a tubular atomizer or a wire mesh packing, and the gas-liquid separation part is a demisting tubular gas-liquid separator. The tubular gas-liquid contact desorber atomization mixing component is a tubular atomizer or a wire mesh packing, and the gas-liquid separation component is a tubular gas-liquid separator.
The method for dehydrating the natural gas glycol by using the efficient compact natural gas glycol dehydration system comprises the following steps:
(1) allowing natural gas with pressure of 2-20MPa to enter a filter separator, removing free liquid water and solid impurities, and discharging from an outlet of the filter separator;
(2) allowing the natural gas discharged in the step (1) to enter a tubular gas-liquid contact absorber, enabling the natural gas to be in parallel flow contact with micron-sized atomized triethylene glycol liquid drops in the tubular gas-liquid contact absorber, discharging the water of the raw material natural gas out of the tubular gas-liquid contact absorber after being absorbed, allowing the water to enter a demister after being cooled by a natural gas/lean glycol heat exchanger, further removing the tiny triethylene glycol liquid drops carried by the natural gas, and discharging the demisted and purified dry natural gas through a demister gas phase outlet to enter a downstream working section;
(3) discharging the rich triethylene glycol absorbing the moisture in the step (2) out of a tubular gas-liquid contact absorber, exchanging heat with triethylene glycol lean solution, then entering a flash tank, flashing the rich triethylene glycol in the flash tank, filtering the rich triethylene glycol through a filter, and then entering a lean/rich ethylene glycol heat exchanger to exchange heat with the lean triethylene glycol;
(4) in the step (3), the triethylene glycol-rich gas enters a tubular gas-liquid contact desorber after heat exchange through a lean/rich glycol heat exchanger, the triethylene glycol-rich gas is atomized into micron-sized liquid drops in the tubular gas-liquid contact desorber and is in countercurrent contact with a stripping agent gasified by a reboiler, and water in the triethylene glycol-rich gas migrates to a gas phase; on one hand, the stripping agent and water in the triethylene glycol form an azeotrope, so that the water is transferred to a gas phase in the form of the azeotrope, on the other hand, the gasified stripping agent can atomize the triethylene glycol into micron-sized liquid drops to increase the gas-liquid mass transfer area, and the triethylene glycol liquid drops and the gasified stripping agent turbulently transfer mass in the same direction, so that the water is promoted to migrate to the gas phase; the desorbed triethylene glycol is discharged from a liquid phase outlet of the tubular gas-liquid contact desorber and enters a reboiler, and the stripping agent is discharged from a gas phase outlet of the tubular gas-liquid contact desorber;
(5) the stripping agent discharged from the gas phase outlet of the tubular gas-liquid contact desorber in the step (4) enters a stripping agent condenser, and is discharged out of the stripping agent condenser after being condensed into a liquid state;
(6) the stripping agent discharged from the stripping agent condenser in the step (5) enters a three-phase separator, water is separated from the stripping agent, the non-condensable gas is led to a tail gas treatment working section, triethylene glycol and water are discharged out of the system, and the stripping agent enters a stripping agent coalescer for coalescence;
(7) in the step (6), the stripping agent is coalesced by a coalescer and then emulsified water in the stripping agent is separated, the coalesced and removed water is discharged out of the system through a bottom outlet, the stripping agent lost in the recovery process of the stripping agent is supplemented through an inlet at the top of the coalescer, and the stripping agent with the emulsified water removed enters a first stripping agent dryer;
(8) the stripping agent entering the first stripping agent dryer in the step (7) sequentially enters the second stripping agent dryer, trace moisture in the stripping agent is further removed through drying, then the stripping agent enters a reboiler, the stripping agent forms an azeotrope with water in triethylene glycol discharged from a liquid phase outlet of the tubular gas-liquid contact desorber in the step (4) in the reboiler, and the azeotrope is gasified, so that the recycling of the stripping agent is realized; the triethylene glycol is discharged from a liquid phase outlet of the reboiler after being further regenerated;
(9) the lean triethylene glycol discharged from the liquid phase outlet of the reboiler in the step (8) enters a lean ethylene glycol storage tank, and a stable liquid level is formed in the storage tank;
(10) and (4) carrying out heat exchange and cooling on the triethylene glycol lean solution in the lean ethylene glycol storage tank in the step (9) by a natural gas/lean ethylene glycol heat exchanger, conveying the triethylene glycol lean solution to a triethylene glycol condenser by a glycol pump, condensing the triethylene glycol condenser, and then feeding the triethylene glycol lean solution into a tubular gas-liquid contact absorber to realize circulation of triethylene glycol.
The volume ratio of the triethylene glycol barren solution to the natural gas in the step (2) is 1:500-1: 10000.
The volume ratio of the triethylene glycol rich solution to the gaseous stripping agent in the step (4) is 1:50-1: 1000.
The flow velocity of natural gas in the tubular gas-liquid contact absorber in the step (2) is 6-30 m/s, the D32 particle size of the atomized triethylene glycol-poor liquid drops is 5-200 mu m, the gas phase flow velocity in the tubular gas-liquid contact desorber in the step (4) is 6-30 m/s, and the D32 particle size of the atomized triethylene glycol-rich liquid drops is 5-200 mu m.
In the step (4), the stripping agent is one or more of isooctane, n-heptane, toluene, ethylbenzene and the like which can form a low-boiling-point azeotrope with water.
In the step (8) and the step (9), the heating temperature in the reboiler is 195 ℃ -204 ℃.
In the step (10), the temperature of the triethylene glycol condenser is 15-40 ℃.
The method is used for dehydrating natural gas glycol in an offshore gas field.
The tubular gas-liquid contact absorber for gas-liquid parallel flow contact absorption and mass transfer enhancement is compact and efficient gas-liquid contact absorption equipment, replaces a traditional absorption tower in a natural gas dehydration process method, and can obviously reduce the space and the weight of a natural gas dehydration treatment device. The glycol is atomized into small drops in the glycol rectification regeneration process, and the gas-liquid mass transfer process of the regeneration system can also be enhanced.
The efficient compact natural gas glycol dehydration system and the method improve the natural gas glycol dehydration system in the prior art, adopt the tubular gas-liquid contact absorber to replace a rectifying column of a traditional glycol regeneration system, further enhance the compactness of the natural gas glycol dehydration system and improve the flexibility of the installation and the arrangement of a dehydration device. The whole device has light weight, small occupied area, low glycol circulation amount and flexible installation and arrangement, and the dehydrated natural gas water dew point meets the requirements of offshore platform production and long-distance gathering and transportation indexes. The problem that the existing natural gas triethylene glycol dehydration process technology adopting the traditional tower type mass transfer device is applied to an offshore platform is solved.
The absorption and regeneration processes of the invention both adopt tubular gas-liquid mass transfer equipment based on micro-droplet gas-liquid parallel flow enhanced mass transfer, and combine the technical advantages of the natural gas dehydration technology by the triethylene glycol method, thus not only ensuring that the water dew point of the gas outlet is maintained in the required range when the flow fluctuation of the gas inlet is large, leading the water dew point of the outlet to reach the standard requirement of gathering or downstream processing technology, but also simplifying the natural gas glycol dehydration system. The requirements of the offshore platform on the size and the weight of the equipment can be met by utilizing the characteristics of high mass transfer efficiency, light weight, small occupied area and flexible installation and arrangement of the tubular gas-liquid contact mass transfer equipment.
The triethylene glycol solution has the advantages of good thermal stability, high boiling point, low steam pressure, easiness in regeneration, high hygroscopicity, small carrying loss, reliability in operation and the like, and the gas-liquid contact mass transfer process is strengthened by utilizing the parallel flow of the atomized micron-sized triethylene glycol liquid drops and the high-speed gas flow in the tubular gas-liquid contact absorber and the tubular gas-liquid contact desorber.
The natural gas dehydration process of the tubular gas-liquid contact mass transfer device based on the micro-droplet gas-liquid parallel flow enhanced mass transfer has the advantages of large treatment capacity and high efficiency, has a large treatment range of liquid-gas ratio, can still achieve an ideal dehydration effect at a low liquid-gas ratio, reduces the consumption of triethylene glycol, and thus saves the energy consumption of a glycol regeneration device. The absorption equipment and the regeneration device both adopt a tubular gas-liquid contact mass transfer device, and the gas-liquid contact mass transfer device can reach the feed gas dehydration balance degree and the outlet water dew point which are difficult to reach by tower-type gas-liquid mass transfer equipment. In addition, the water content, namely the dehydration balance degree, of the outlet gas and the dew point of the outlet gas can be effectively controlled by regulating the injection amount of the glycol liquid and the particle size of the atomized liquid drops. Therefore, the preferable conditions make the natural gas-glycol dehydration process of the tubular gas-liquid contact mass transfer device based on micro-droplet gas-liquid cocurrent flow reinforced contact mass transfer far superior to the traditional tower dehydration process.
The invention has the following beneficial effects:
1) the tubular gas-liquid contact absorption dehydration device comprises a tubular atomization component and a tubular gas-liquid separator, wherein the tubular atomization component atomizes glycol lean solution into micron-sized liquid drops in high-speed gas flow, and the high-speed gas flow and the micron-sized liquid drops form a gas-liquid high-dispersion system in a contact mass transfer pipe section, so that the gas-liquid contact area is remarkably increased, the gas-liquid absorption mass transfer dehydration effect is improved, and the dehydration efficiency is higher;
2) the tubular gas-liquid contact dehydration regeneration device comprises a tubular atomization component and a tubular gas-liquid separator, the tubular atomization component atomizes glycol rich liquid into micron-sized liquid drops in high-speed gas flow, the high-speed gas flow and the micron-sized liquid drops form a gas-liquid high-dispersion system in a contact mass transfer pipe section, the gas-liquid contact area is remarkably increased, so that moisture in the glycol rich liquid drops is volatilized as far as possible, triethylene glycol lean solution is obtained through regeneration, and the glycol regeneration efficiency is higher;
3) the glycol liquid holdup in the tubular gas-liquid contact mass transfer equipment is low, the gas-liquid contact mass transfer efficiency of a gas-liquid high dispersion system formed by micron-sized liquid drops is high, and the dehydration system designed by adopting the tubular gas-liquid contact mass transfer process has the advantage of low glycol circulation amount, can obviously reduce the energy consumption of glycol regeneration, and is more beneficial to industrial application.
4) By combining the natural gas dehydration process of the tubular gas-liquid contact mass transfer enhancement based on the micro-droplet high-dispersion tubular gas-liquid contact mass transfer dehydration and regeneration device, the flash tank and the reboiler in the technology, the organic combination of the tubular micro-droplet enhancement gas-liquid mass transfer technology, the traditional triethylene glycol dehydration tower process and the ethylene glycol rectification column regeneration process is realized. Compared with the dehydration process adopting the traditional tower-type gas-liquid contact mass transfer equipment, the whole process has the characteristics of high absorption mass transfer efficiency, low outlet dew point, light weight of the equipment, small occupied area, flexible installation and arrangement, high system robustness and the like.
The specific embodiment is as follows:
referring to fig. 1, the invention provides a high-efficiency compact natural gas glycol dehydration process, which comprises a filter separator underflow valve 1, a filter separator 2, a tubular gas-liquid contact absorber 3, a triethylene glycol condenser 4, a glycol pump 5, a natural gas/lean glycol heat exchanger 6, a demister 7, a demister underflow valve 8, a lean glycol storage tank 9, a lean/rich glycol heat exchanger 10, a tubular gas-liquid contact desorber 11, a condenser 12, a three-phase separator 13, a stripping agent pump 14, a first stop valve 15, a stripping agent injection stop valve 16, a coalescer 17, a coalescer drain valve 18, a first stripping agent dryer 19, a second stripping agent dryer 20, a stripping agent heater 21, a reboiler 22, a glycol filter 23, a flash tank 24 and a second stop valve 25.
The bottom outlet of the filter separator 2 is connected with a filter separator underflow valve 1, the outlet of the filter separator underflow valve 1 is connected with a downstream sewage disposal system, and the top outlet of the filter separator 2 is connected with a gas phase inlet of a tubular gas-liquid contact absorber 3;
the gas phase outlet of the tubular gas-liquid contact absorber 3 is connected with the natural gas inlet of the natural gas/lean glycol heat exchanger 6, the natural gas outlet of the natural gas/lean glycol heat exchanger 6 is connected with the inlet of a demister 7, the gas phase outlet at the upper part of the demister 7 is connected with a downstream natural gas treatment section, the liquid phase outlet at the lower part of the demister 7 is connected with the inlet of a demister underflow valve 8, and the outlet of the demister underflow valve 8 is connected with a flash tank 24.
A liquid phase outlet at the lower part of the tubular gas-liquid contact absorber 3 is connected with a second stop valve 25, the second stop valve 25 is connected with a flash drum 24, a gas phase outlet at the upper part of the flash drum 24 is connected with a tail gas treatment system, a liquid phase outlet at the bottom of the flash drum 24 is connected with an inlet of a glycol filter 23, an outlet of the glycol filter 23 is connected with a glycol-rich inlet of the lean/glycol-rich heat exchanger 10, a glycol-rich outlet of the lean/glycol-rich heat exchanger 10 is connected with a liquid phase inlet of the tubular gas-liquid contact desorber 11, and a liquid phase outlet of the tubular gas-liquid contact desorber 11 is connected with an inlet at the upper part of the reboiler 22;
a gas phase outlet of the tubular gas-liquid contact desorber 11 is connected with an inlet of a condenser 12, an outlet of the condenser 12 is connected with an inlet of a three-phase separator 13, a non-condensable gas outlet of the three-phase separator 13 leads to tail gas treatment, and a water outlet is arranged at the lower end of the three-phase separator 13;
the outlet of the stripping agent of the three-phase separator 13 is connected with the inlet of a stripping agent pump 14, the outlet of the stripping agent pump 14 is connected with the inlet of a stripping agent coalescer 17, the outlet of the stripping agent coalescer 17 is connected with the inlet of a first stripping agent dryer 19, the upper part of the stripping agent coalescer 17 is provided with a stripping agent feeding port and is connected with a stripping agent injection stop valve 16, and the stripping agent is fed through the inlet of the stripping agent injection stop valve 16. The lower part of the stripping agent coalescer 17 is provided with a water discharge port connected with a coalescer water discharge valve 18.
The first stripping agent dryer 19, the second stripping agent dryer 20 and the stripping agent heater 21 are sequentially connected, and an outlet of the stripping agent heater 21 is connected with a stripping agent inlet at the lower part of the reboiler 22, so that the circulation of the stripping agent is realized.
The gas phase outlet of the reboiler 22 is connected with the gas phase inlet of the tubular gas-liquid contact desorber 11, the liquid phase outlet of the reboiler 22 is connected with the lean glycol inlet of the lean/rich glycol heat exchanger 6, the lean glycol outlet of the lean/rich glycol heat exchanger 6 is connected with the inlet of the lean glycol storage tank 9, the bottom outlet of the lean glycol storage tank 9 is connected with the lean glycol inlet of the natural gas/lean glycol heat exchanger 6, the lean glycol outlet of the natural gas/lean glycol heat exchanger 9 is connected with the inlet of the glycol pump 5, the outlet of the glycol pump 5 is connected with the inlet of the triethylene glycol condenser 4, and the outlet of the triethylene glycol condenser 4 is connected with the liquid phase inlet of the tubular gas-liquid contact absorber 3, so that the circulation of the triethylene glycol is realized.
The invention utilizes the process for carrying out the compact and high-efficiency tubular triethylene glycol method natural gas dehydration based on the micro-droplet reinforced gas-liquid mass transfer, which comprises the following steps:
(1) allowing natural gas with pressure of 2-20MPa to enter a filter separator, removing free liquid water and solid impurities, and discharging from an outlet of the filter separator;
(2) allowing the natural gas discharged in the step (1) to enter a tubular gas-liquid contact absorber, enabling the natural gas to be in parallel flow contact with micron-sized atomized triethylene glycol liquid drops in the tubular gas-liquid contact absorber, discharging the water of the raw gas out of the tubular gas-liquid contact absorber after being absorbed, allowing the water to enter a demister after being cooled by a natural gas/lean glycol heat exchanger, further removing the tiny triethylene glycol liquid drops carried by the natural gas, and discharging the demisted and purified dry natural gas through a demister gas phase outlet to enter a downstream working section;
(3) discharging the rich triethylene glycol absorbing the moisture in the step (2) out of a tubular gas-liquid contact absorber, exchanging heat with triethylene glycol lean solution, then entering a flash tank, flashing the rich triethylene glycol in the flash tank, filtering the rich triethylene glycol through a filter, and then entering a lean/rich ethylene glycol heat exchanger to exchange heat with the lean triethylene glycol;
(4) in the step (3), the triethylene glycol-rich gas enters a tubular gas-liquid contact desorber after heat exchange through a lean/rich glycol heat exchanger, the triethylene glycol-rich gas is atomized into micron-sized liquid drops in the tubular gas-liquid contact desorber and is in countercurrent contact with a stripping agent gasified by a reboiler, and water in the triethylene glycol-rich gas migrates to a gas phase; on one hand, the stripping agent and water in the triethylene glycol form an azeotrope, so that the water is transferred to a gas phase in the form of the azeotrope, on the other hand, the gasified stripping agent can atomize the triethylene glycol into micron-sized liquid drops to increase the gas-liquid mass transfer area, and the triethylene glycol liquid drops and the gasified stripping agent turbulently transfer mass in the same direction, so that the water is promoted to migrate to the gas phase; the desorbed triethylene glycol is discharged from a liquid phase outlet of the tubular gas-liquid contact desorber and enters a reboiler, and the stripping agent is discharged from a gas phase outlet of the tubular gas-liquid contact desorber;
(5) the stripping agent discharged from the gas phase outlet of the tubular gas-liquid contact desorber in the step (4) enters a stripping agent condenser, and is discharged out of the stripping agent condenser after being condensed into a liquid state;
(6) the stripping agent discharged from the stripping agent condenser in the step (5) enters a three-phase separator, water is separated from the stripping agent, the non-condensable gas is led to a tail gas treatment working section, triethylene glycol and water are discharged out of the system, and the stripping agent enters a stripping agent coalescer for coalescence;
(7) in the step (6), the stripping agent is coalesced by a coalescer and then emulsified water in the stripping agent is separated, the coalesced and removed water is discharged out of the system through a bottom outlet, the stripping agent lost in the recovery process of the stripping agent is supplemented through an inlet at the top of the coalescer, and the stripping agent with the emulsified water removed enters a first stripping agent dryer;
(8) the stripping agent entering the first stripping agent dryer in the step (7) sequentially enters the second stripping agent dryer, trace moisture in the stripping agent is further removed through drying, then the stripping agent enters a reboiler, the stripping agent forms an azeotrope with water in triethylene glycol discharged from a liquid phase outlet of the tubular gas-liquid contact desorber in the step (4) in the reboiler, and the azeotrope is gasified, so that the recycling of the stripping agent is realized; the triethylene glycol is discharged from a liquid phase outlet of the reboiler after being further regenerated;
(9) the lean triethylene glycol discharged from the liquid phase outlet of the reboiler in the step (8) enters a lean ethylene glycol storage tank, and a stable liquid level is formed in the storage tank;
(10) and (4) carrying out heat exchange and cooling on the triethylene glycol lean solution in the lean ethylene glycol storage tank in the step (9) by a natural gas/lean ethylene glycol heat exchanger, conveying the triethylene glycol lean solution to a triethylene glycol condenser by a glycol pump, condensing the triethylene glycol condenser, and then feeding the triethylene glycol lean solution into a tubular gas-liquid contact absorber to realize circulation of triethylene glycol.
In certain embodiments of the invention, the volume ratio of triethylene glycol to natural gas in step (2) is from 1:500 to 1: 10000.
In certain embodiments of the present invention, in step (2), the triethylene glycol lean solution concentration can reach 99.99%, the equilibrium degree of dehydration of the natural raw material gas reaches more than 95%, and the outlet dew point reaches below-60 ℃.
In some embodiments of the invention, the tubular gas-liquid contact absorber atomization component in step (2) is a tubular atomizer or a wire mesh packing, the gas-liquid separation component is a demisting type tubular gas-liquid separator,
in certain embodiments of the present invention, the tubular gas-liquid contact desorber atomizing and mixing component in step (4) is a tubular atomizer or a wire mesh packing, and the gas-liquid separation component is a tubular gas-liquid separator.
In certain embodiments of the invention, the volume ratio of triethylene glycol rich to gaseous stripping agent in step (4) is from 1:50 to 1: 1000.
In some embodiments of the present invention, the flow rate of the natural gas in the tubular gas-liquid contact absorber in step (2) is 6 to 30m/s, the particle size of D32 of the atomized triethylene glycol-poor liquid droplets is 5 to 200 μm, the flow rate of the gas phase in the tubular gas-liquid contact desorber in step (4) is 6 to 30m/s, and the particle size of D32 of the atomized triethylene glycol-rich liquid droplets is 5 to 200 μm.
In certain embodiments of the present invention, the stripping agent in step (4) is one or more of isooctane, n-heptane, toluene, ethylbenzene, etc., which can form a low boiling azeotrope with water.
In certain embodiments of the invention, the reboiler temperature in steps (8) and (9) is 195 ℃ to 204 ℃.
In certain embodiments of the invention, in step (10), the temperature of the triethylene glycol condenser is between 15 ℃ and 40 ℃.
Example 1
The above apparatus and process were used to remove gaseous water from natural gas with triethylene glycol:
the natural gas pressure entering the system is 7MPa, the volume ratio of the triethylene glycol lean solution to the natural gas to be treated is 1:10000, the volume ratio of the using amount of a stripping agent to the using amount of the triethylene glycol rich solution is 0.15:1, the stripping agent is n-heptane, the temperature of a triethylene glycol condenser is 35 ℃, the natural gas flow rate in a tubular gas-liquid contact absorber is 12m/s, the particle size of triethylene glycol lean solution atomized liquid drops D32 is 100 mu m, the gas flow rate in the tubular gas-liquid contact desorber is 12m/s, the particle size of triethylene glycol rich solution atomized liquid drops D32 is 100 mu m, and the temperature of a reboiler is 204 ℃; under the process condition, the purity of the regenerated triethylene glycol barren solution reaches 99.99 wt%, and the water dew point of the dehydrated natural gas reaches-60 ℃.
Example 2
As shown in example 1, other conditions are unchanged, the flow rate of the natural gas in the tubular gas-liquid contact absorber is 20m/s, the particle size of the atomized droplets D32 of the triethylene glycol lean solution is 60 μm, the flow rate of the gas phase in the tubular gas-liquid contact desorber is 20m/s, and the particle size of the atomized droplets D32 of the triethylene glycol rich solution is 60 μm, so that the purity of the regenerated triethylene glycol lean solution reaches 99.99 wt%, and the water dew point of the dehydrated natural gas reaches-70 ℃.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.