Triethylene glycol dehydration unit reboiler column tail gas recovery unit

Abstract

The present application provides a triethylene glycol dehydration device reboiler rectification column tail gas recovery device, relates to the technical field of triethylene glycol dehydration treatment.The triethylene glycol dehydration device reboiler rectification column tail gas recovery device, including air cooler, water distribution tank, the air cooler output end is connected with water distribution tank feed end through first centrifugal pump communication, the water distribution tank pressure detection end is provided with pressure gauge, the water distribution tank upper portion is provided with small flow exhaust port, and is communicated with fuel device through pipeline, the water distribution tank lower part output end is communicated with compression tank through pipeline, the pipeline between water distribution tank and compression tank is provided with water jet pressurizing device, the compression tank exhaust and absorption tower lower part gas inlet are communicated through pipeline.The cooperation of water jet pressurizing device and water distribution tank makes a small part of tail gas be used for combustion in fuel device, avoids the problem of excessive heavy hydrocarbon concentration, most of the tail gas enters the compression tank and is input into the absorption tower as stripping gas, which achieves the effect of further purifying triethylene glycol.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of triethylene glycol dehydration treatment, in particular to a tail gas recovery device of a reboiler rectification column of a triethylene glycol dehydration device. BACKGROUND

[0002] The triethylene glycol (TEG) dehydration device is a main device for natural gas treatment, which is used for removing gaseous water in natural gas to prevent water vapor from being separated from natural gas to form liquid water due to environmental temperature changes in the conveying process, and the generated liquid water can accelerate the corrosion of the pipeline and reduce the gas conveying efficiency of the pipeline. Solid ice can cause the blockage of valves and pipelines, affecting the smooth gas conveying.

[0003] During the operation of the triethylene glycol dehydration device, a certain amount of tail gas is generated due to its process characteristics, and the main causes are as follows:

[0004] (1) When the reboiler of the triethylene glycol dehydration device heats the regenerated triethylene glycol, the control temperature is 200℃, and the triethylene glycol cracking temperature is 206.7℃, so the working temperature of the triethylene glycol is very close to the cracking temperature, which inevitably causes some triethylene glycol to decompose, especially some solid crystals in the old and worn triethylene glycol fire tube, causing local overheating of the fire tube, resulting in serious decomposition of the triethylene glycol, and the decomposition products have a strong acid smell. Some gas wells have more heavy hydrocarbons in the gas composition, which are easily dissolved in triethylene glycol, and are heated and vaporized together with triethylene glycol in the reboiler and discharged into the atmosphere, which also produces a strong oil and gas odor.

[0005] (2) Most of the triethylene glycol is powered by a kimray pump, which is a gas / liquid power pump driven by pressure. During the operation of the device, the high-pressure gas of the absorption tower provides power and becomes low-pressure gas together with the triethylene glycol into the regeneration system. Although most of the gas is removed through the flash tank, some gas still enters the reboiler together with the triethylene glycol (theoretically, 8L of non-sulfur natural gas can be dissolved in 1L of triethylene glycol at 6.8MPa). After the triethylene glycol is heated, the content of dissolved gas decreases, and the gas is separated from the triethylene glycol and discharged into the atmosphere with water vapor.

[0006] (3) During the circulation of triethylene glycol, some liquid hydrocarbons are continuously adsorbed, and the composition of the hydrocarbons is related to the gas composition of the station. Some heavy hydrocarbons, especially aromatic hydrocarbons, have a large solubility in triethylene glycol and are adsorbed by triethylene glycol during the dehydration process in the tower. During regeneration, these heavy hydrocarbons are heated to become gas and discharged into the atmosphere with water vapor, causing environmental pollution and safety hazards, polluting the atmospheric environment and affecting the lives of station staff and surrounding people.

[0007] (4) Some gas stations contain trace amounts of toxic and harmful substances such as benzene, xylene, and hydrogen sulfide, which are discharged into the atmosphere with water vapor at the top of the rectification column.

[0008] In view of the above reasons, the treatment of tail gas is particularly important. However, the traditional treatment method of the tail gas of the reboiler rectification column of the triethylene glycol dehydration device is incineration, that is, the tail gas is used as fuel gas, but if the tail gas contains a large amount of heavy hydrocarbon, it is very dangerous to directly enter the incinerator. SUMMARY

[0009] In view of the deficiencies of the prior art, the present application provides a triethylene glycol dehydration device reboiler rectification column tail gas recovery device, which solves the problem that tail gas containing a large amount of heavy hydrocarbon directly entering an incinerator is very dangerous. At the same time, in cooperation with a water separation tank, a compression tank and an absorption tower, most of the tail gas is used as stripping gas, which further purifies the triethylene glycol.

[0010] To achieve the above object, the present application is realized by the following technical scheme: a triethylene glycol dehydration device reboiler rectification column tail gas recovery device, comprising an air cooler and a water separation tank, the output end of the air cooler is communicated with the feed end of the water separation tank through a first centrifugal pump, a pressure gauge is arranged at the pressure detection end of the water separation tank, a small flow exhaust port is arranged at the upper part of the water separation tank and is communicated with a fueler through a pipeline, the lower output end of the water separation tank is communicated with a compression tank through a pipeline, a water jet pressurizing device is arranged on the pipeline between the water separation tank and the compression tank, the exhaust port of the compression tank is communicated with the lower gas inlet of an absorption tower through a pipeline, the upper liquid inlet of the absorption tower is communicated with a triethylene glycol buffer tank, the liquid outlet at the bottom end of the absorption tower is communicated with a triethylene glycol reboiler, and the gas outlet at the upper end of the absorption tower is communicated with a lean liquid rectification column.

[0011] Preferably, the water jet pressurizing device comprises a jet device, one input end of the jet device is communicated with the lower output end of the water separation tank through a pipeline, an electromagnetic switch valve is arranged on the pipeline between the jet device and the water separation tank, the other input end of the jet device is communicated with the liquid discharge end of the compression tank through a circulating pump, and the output end of the jet device is communicated with the input end of the compression tank through a pipeline.

[0012] Preferably, the liquid discharge end of the compression tank is further connected with a waste water receiving device, a second centrifugal pump and a pneumatic switch are sequentially arranged on the connecting pipeline from the liquid discharge end of the compression tank to the waste water receiving device.

[0013] Preferably, the middle liquid inlet of the absorption tower is communicated with the output end of a triethylene glycol flash tank through a pipeline.

[0014] Preferably, a flame arrestor is further arranged on the pipeline between the small flow exhaust port at the upper part of the water separation tank and the fueler.

[0015] Preferably, the input end of the air cooler is communicated with the gas outlet of the rich liquid rectification column.

[0016] Preferably, the process flow of the recovery device comprises the following steps:

[0017] Step one, the mixed gas discharged from the vent of the rich liquid rectification column is cooled by an air cooler, and the liquefied liquid and non-condensable gas are transported to a water separation tank by a first centrifugal pump;

[0018] Step two, a small amount of gas is input to the fueler from the small flow vent of the upper part of the water separation tank and mixed with the conventional input fuel gas to be supplied to combustion;

[0019] Step three, as the device operates, the water level and pressure in the water separation tank become higher and higher, when the pressure is higher than the highest set value, the circulating pump is started, the electromagnetic switch valve is opened, the circulating water in the compression tank is lifted by the circulating pump, passes through the jet nozzle at high speed, forms a negative pressure at the nozzle outlet, and sucks the condensed water and gas in the water separation tank, the condensed water and gas sucked and the original circulating water are pressurized to enter the compression tank, and gas-liquid separation is realized under the action of gravity and the filler in the tank, and the gas at the top of the tank enters the absorption tower as stripping gas through the lower gas inlet of the absorption tower;

[0020] Step four, the triethylene glycol rich liquid from the triethylene glycol flash tank enters the middle part of the absorption tower, and part of the triethylene glycol regenerated lean liquid is introduced from the triethylene glycol buffer tank, and then the lean liquid enters the upper part of the absorption tower, so that the gas-liquid countercurrently contacts in the absorption tower;

[0021] Step five, the triethylene glycol rich liquid and lean liquid are mixed and heat exchanged, and then output from the bottom of the absorption tower to the triethylene glycol reboiler, and finally enter the rich liquid rectification column for regeneration;

[0022] Step six, the gas in the absorption tower enters the lean liquid rectification column as stripping gas again, and the triethylene glycol is further purified;

[0023] Step seven, when the pressure in the water separation tank decreases to the lowest set value, the electromagnetic switch valve is closed, the circulating pump is closed, and the above process is repeated after the pressure in the water separation tank rises to the highest set value.

[0024] The present application provides a triethylene glycol dehydration device reboiler rectification column tail gas recovery device. It has the following beneficial effects:

[0025] 1. The present application uses a small part of the tail gas for combustion in the fueler through the cooperation of the water jet pressurizing device and the water separation tank, avoiding the problem of too high concentration of heavy hydrocarbons, and most of the tail gas enters the compression tank and is input into the absorption tower as stripping gas, achieving the effect of further purifying triethylene glycol, and at the same time, the tail gas circulates in the whole system and is fully recycled, so that the harm of triethylene glycol regeneration waste gas in the original process to the environment, equipment and workers is reduced, and the energy is fully recycled, which is beneficial to energy saving and emission reduction.

[0026] 2. The present application makes the reboiler operate under negative pressure for a long time, which reduces the triethylene glycol surface water vapor

[0027] The partial pressure makes the lean glycol concentration of the regenerated glycol further increase, so that the dew point of the natural gas can be reduced by 3-5 ℃, and the dehydration effect of the original device is improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The figure is a process flow diagram of the present application.

[0029] Wherein, 1, air cooler; 2, first centrifugal pump; 3, water distribution tank; 4, electromagnetic switch valve; 5, jet device; 6, compression tank; 7, circulating pump; 8, absorption tower; 9, triethylene glycol flash tank; 10, triethylene glycol buffer tank; 11, lean liquid rectification column; 12, triethylene glycol reboiler; 13, rich liquid rectification column; 14, pressure gauge; 15, second centrifugal pump; 16, pneumatic switch; 17, fuel device; 18, flame arrester. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application. Embodiment one

[0031] Please refer to the accompanying Figure 1 The triethylene glycol dehydration device reboiler rectification column tail gas recovery device provided by the embodiments of the present application comprises an air cooler 1 and a water distribution tank 3. The output end of the air cooler 1 is communicated with the feed end of the water distribution tank 3 through a first centrifugal pump 2. A pressure gauge 14 is arranged at the pressure detection end of the water distribution tank 3. A small-flow exhaust port is arranged at the upper part of the water distribution tank 3 and is communicated with a fuel device 17 through a pipeline. The output end of the lower part of the water distribution tank 3 is communicated with a compression tank 6 through a pipeline. A water jet pressurizing device is arranged on the pipeline between the water distribution tank 3 and the compression tank 6. The exhaust port of the compression tank 6 is communicated with the lower gas inlet of an absorption tower 8 through a pipeline. The upper liquid inlet of the absorption tower 8 is communicated with a triethylene glycol buffer tank 10. The bottom liquid outlet of the absorption tower 8 is communicated with a triethylene glycol reboiler 12. The upper end exhaust port of the absorption tower 8 is communicated with a lean liquid rectification column 11.

[0032] The tail gas is condensed after passing through the air cooler 1 and then enters the water distribution tank 3. Part of the tail gas is input to the fuel device 17 through the small-flow exhaust port at the upper part of the water distribution tank 3 and is mixed with the conventional input fuel gas to provide combustion, so that the problem of excessively high heavy hydrocarbon concentration is avoided.

[0033] When the pressure in the water separation tank 3 is higher than the highest set value (+5KPa), the circulating pump 7 is started, the electromagnetic switch valve 4 is opened, the circulating water in the compression tank 6 is lifted by the circulating pump 7, and high-speed through the nozzle of the water jet device 5, a negative pressure is formed at the outlet of the nozzle, the condensed water and gas in the water separation tank 3 are sucked, the condensed water and tail gas sucked and the original circulating water are pressurized into the compression tank 6 together, and the gas-liquid separation is realized under the action of gravity and the filler in the tank. The gas at the top of the tank enters the absorption tower 8 from the lower gas inlet of the absorption tower 8 as stripping gas, the triethylene glycol rich liquid from the triethylene glycol flash tank 9 is further purified by countercurrent contact with the triethylene glycol regenerated lean liquid and stripping gas, and the rich liquid and lean liquid are mixed and heat exchanged and then enter the rich liquid rectification column 13 from the bottom of the absorption tower 8 for regeneration. The tail gas enters the lean liquid rectification column 11 again as stripping gas to further purify the triethylene glycol.

[0034] Through the cooperation of the water jet pressurizing device and the water separation tank 3, a small part of the tail gas is used for combustion in the fuel device 17, avoiding the problem of too high concentration of heavy hydrocarbons, and most of the tail gas enters the compression tank 6 and is used as stripping gas in the absorption tower 8, achieving the effect of further purifying the triethylene glycol. At the same time, the tail gas circulates in the whole system and can be fully recycled. In summary, it can not only reduce the harm of triethylene glycol regeneration waste gas in the original process to the environment, equipment and workers, but also realize the full recycling of energy, which is beneficial to energy saving and emission reduction.

[0035] At the same time, the reboiler is operated at negative pressure for a long time, which reduces the partial pressure of water vapor on the surface of triethylene glycol, further increases the concentration of regenerated lean glycol, and thus reduces the dew point of natural gas by 3-5℃, improving the dehydration effect of the original device.

[0036] The water jet pressurizing device comprises the water jet device 5, one input end of the water jet device 5 is communicated with the lower output end of the water separation tank 3 through a pipeline, an electromagnetic switch valve 4 is arranged on the pipeline between the water jet device 5 and the water separation tank 3, the other input end of the water jet device 5 is communicated with the liquid discharge end of the compression tank 6 through the circulating pump 7, and the output end of the water jet device 5 is communicated with the input end of the compression tank 6 through a pipeline.

[0037] The circulating pump 7 is started, the electromagnetic switch valve 4 is opened, the circulating water in the compression tank 6 is lifted by the circulating pump 7, high-speed through the nozzle of the water jet device 5, a negative pressure is formed at the outlet of the nozzle, the condensed water and gas in the water separation tank 3 are sucked, and the condensed water and tail gas sucked and the original circulating water are pressurized into the compression tank 6 together.

[0038] The liquid discharge end of the compression tank 6 is further connected with a waste water receiving device, and a second centrifugal pump 15 and a pneumatic switch 16 are sequentially arranged on the connecting pipeline from the liquid discharge end of the compression tank 6 to the waste water receiving device.

[0039] When the circulating water in the compression tank 6 is too much, the second centrifugal pump 15 is started and the pneumatic switch 16 is opened, and the excess circulating water is discharged to the waste water receiving device.

[0040] The middle liquid inlet of the absorption tower 8 is connected with the output end of the triethylene glycol flash tank 9 through a pipeline.

[0041] The triethylene glycol rich solution from the triethylene glycol flash tank 9 is connected to the absorption tower 8, so that the stripping gas is further purified.

[0042] A flame arrester 18 is further arranged on the pipeline between the small flow gas outlet at the upper part of the water separation tank 3 and the fueler 17.

[0043] The flame arrester 18 is used to avoid the backflow of the flame.

[0044] The input end of the air cooler 1 is connected with the gas outlet of the rich solution rectification column 13.

[0045] The air cooler 1 is used to cool and condense the tail gas discharged from the rich solution rectification column 13. Embodiment Two

[0046] On the basis of the above-mentioned embodiment, the embodiment provides a process flow of the tail gas recovery device of the triethylene glycol dehydration device reboiler rectification column, which comprises the following steps:

[0047] Step one, the mixed gas discharged from the gas outlet of the rich solution rectification column 13 is cooled and condensed by the air cooler 1, and the liquefied liquid and non-condensable gas are transported to the water separation tank 3 by the first centrifugal pump 2;

[0048] Step two, a small part of the gas is input to the fueler 17 through the small flow gas outlet at the upper part of the water separation tank 3 and mixed with the conventional input fuel gas to supply combustion;

[0049] Step three, with the operation of the device, the water level and pressure in the water separation tank 3 become higher and higher, when the pressure is higher than the highest set value, the circulating pump 7 is started, the electromagnetic switch valve 4 is opened, and the circulating water in the compression tank 6 is lifted by the circulating pump 7, passes through the nozzle of the jetifier 5 at a high speed, and forms a negative pressure at the outlet of the nozzle to suck the condensed water and gas in the water separation tank 3, and the condensed water and gas sucked together with the original circulating water are pressurized into the compression tank 6, and the gas-liquid separation is realized under the action of gravity and the filler in the tank, and the gas at the top of the tank enters the absorption tower 8 through the lower gas inlet of the absorption tower 8 as the stripping gas;

[0050] Step four, the triethylene glycol rich solution from the triethylene glycol flash tank 9 enters the middle part of the absorption tower 8, and part of the triethylene glycol regenerated lean solution from the triethylene glycol buffer tank 10 enters the upper part of the absorption tower 8, so that the gas-liquid countercurrently contacts in the absorption tower 8;

[0051] Step five, the triethylene glycol rich solution and the lean solution are mixed and heat-exchanged, and then output from the bottom of the absorption tower 8 to the triethylene glycol reboiler 12, and finally enter the rich solution rectification column 13 for regeneration;

[0052] Step six, the gas from absorption tower 8 is again used as stripping gas to enter lean liquid rectification column 11 to further purify triethylene glycol.

[0053] Step seven, when the pressure in water knockout drum 3 drops to the lowest set value, close electromagnetic switch valve 4 and close circulating pump 7. Wait until the pressure in water knockout drum 3 rises to the highest set value, then repeat the above process.

[0054] While the embodiments of the application have been illustrated and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and alterations can be made therein without departing from the spirit and scope of the application, which is defined by the following claims and their equivalents.

Claims

1. The tail gas recovery device of the rectifying column of the triethylene glycol dehydration device reboiler, comprising an air cooler (1), a water segregating tank (3), characterized in that, The air cooler (1) output end and the water distribution tank (3) feed end are communicated through the first centrifugal pump (2), the water distribution tank (3) pressure detection end is provided with a pressure gauge (14), the water distribution tank (3) upper portion is provided with a small flow exhaust port, and is communicated with the fuel device (17) through a pipeline, the water distribution tank (3) lower portion output end is communicated with the compression tank (6) through a pipeline, the pipeline between the water distribution tank (3) and the compression tank (6) is provided with a water jet pressurizing device, the compression tank (6) exhaust port and the absorption tower (8) lower portion gas inlet are communicated through a pipeline, the absorption tower (8) upper portion liquid inlet is communicated with the triethylene glycol buffer tank (10), the absorption tower (8) bottom end liquid outlet is communicated with the triethylene glycol reboiler (12), and the absorption tower (8) upper end exhaust port is communicated with the lean liquid rectification column (11); The absorption tower (8) middle portion liquid inlet is communicated with the triethylene glycol flash tank (9) output end through a pipeline; The air cooler (1) input end is communicated with the rich liquid rectification column (13) exhaust port; The water jet pressurizing device includes a jet device (5), one input end of the jet device (5) is communicated with the water distribution tank (3) lower portion output end through a pipeline, and the pipeline between the jet device (5) and the water distribution tank (3) is provided with an electromagnetic switch valve (4), another input end of the jet device (5) is communicated with the compression tank (6) liquid outlet through a circulating pump (7), and the jet device (5) output end is communicated with the compression tank (6) input end through a pipeline.

2. The triethylene glycol dehydration plant reboiler column vent recovery apparatus of claim 1, wherein, The compression tank (6) liquid outlet is also connected with a waste water receiving device, and a second centrifugal pump (15) and a pneumatic switch (16) are sequentially arranged on the connecting pipeline from the compression tank (6) liquid outlet to the waste water receiving device.

3. The triethylene glycol dehydration plant reboiler column vent recovery apparatus of claim 2, wherein, The pipeline between the water distribution tank (3) upper portion small flow exhaust port and the fuel device (17) is also provided with a fire arrester (18).

4. The triethylene glycol dehydration plant reboiler column vent recovery apparatus of claim 3, wherein, The process flow of the recycling device includes the following steps: Step one, the mixed gas discharged from the rich liquid rectification column (13) exhaust port is cooled by the air cooler (1), and the liquefied liquid and incondensable gas are transported to the water distribution tank (3) by the first centrifugal pump (2); Step two, a small part of gas is input to the fuel device (17) through the water distribution tank (3) upper portion small flow exhaust port and mixed with the conventional input fuel gas to supply combustion; Step three, with the operation of the device, the water level and pressure in the water distribution tank (3) are higher and higher, when the pressure is higher than the highest set value, the circulating pump (7) is started, the electromagnetic switch valve (4) is opened, the circulating water in the compression tank (6) is lifted through the circulating pump (7), high-speed passes through the jet device (5) nozzle, forms a negative pressure at the nozzle outlet, and the condensed water and gas in the water distribution tank (3) are sucked, the condensed water and gas sucked and the original circulating water are pressurized into the compression tank (6) together, and the gas-liquid separation is realized under the action of gravity and the tank filler, and the tank top gas enters the absorption tower (8) as stripping gas through the absorption tower (8) lower portion gas inlet at a certain pressure; Step four, triethylene glycol rich liquid from triethylene glycol flash tank (9) enters the middle of the absorption tower (8), and part of the triethylene glycol lean liquid from the triethylene glycol buffer tank (10) enters the upper part of the absorption tower (8), then the gas and liquid contact countercurrently in the absorption tower (8); Step five, after mixing and heat exchange, the triethylene glycol rich liquid and lean liquid are output from the bottom of the absorption tower (8) to the triethylene glycol reboiler (12), and finally enter the rich liquid rectification column (13) for regeneration; Step six, the gas in the absorption tower (8) enters the lean liquid rectification column (11) again as stripping gas, and the triethylene glycol is further purified; Step seven, when the pressure in the water separation tank (3) drops to the lowest set value, close the electromagnetic switch valve (4) and the circulating pump (7), and wait for the pressure in the water separation tank to rise to the highest set value, then repeat the above process.

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