CN104696700B - methane gas recovery system and recovery method - Google Patents

methane gas recovery system and recovery method Download PDF

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Publication number
CN104696700B
CN104696700B CN201510106834.5A CN201510106834A CN104696700B CN 104696700 B CN104696700 B CN 104696700B CN 201510106834 A CN201510106834 A CN 201510106834A CN 104696700 B CN104696700 B CN 104696700B
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methane gas
methane
flash vessel
gas
pressure
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CN104696700A (en
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陈�峰
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ENN Science and Technology Development Co Ltd
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ENN Science and Technology Development Co Ltd
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Abstract

The present invention relates to a kind of methane gas recovery system and recovery method, the system includes flash vessel, the air inlet of the flash vessel is used to receive methane gas, the gas outlet of the flash vessel is connected with the air inlet of compressor, the gas outlet of the compressor is connected with cooling device, and the cooling device is connected to the refluxing opening of the flash vessel by choke valve.The flow of not only gas recovery of the invention is simple, reduces the recovery power consumption of methane, and I&M cost is low, and the rate of recovery is high, and it is that liquefied natural gas can be with market goods locally to reclaim product.

Description

Methane gas recovery system and recovery method
Technical field
The present invention relates to the technical field of gas recycling, refers in particular to apply in liquefied natural gas (LNG) storage With the re-liquefied of boil-off gas in transportation (BOG) and recovery.
Background technology
Liquefied natural gas (LNG) main component is methane, and it is the energy most clean on the earth to be recognized, colourless, tasteless, nothing Malicious and non-corrosiveness, its volume are about the 1/625 of same amount gaseous natural gas volume, and the weight of liquefied natural gas is only androgynous ponding 45% or so.Liquefied natural gas be natural gas is compressed, be cooled to its boiling temperature after become liquid, usual liquefied natural gas It is stored in subzero 161.5 degrees Celsius, in 0.1MPa or so low-temperature storage tank, is transported with special purpose ship or oil truck, weight during use New gasification.It is very small to air pollution after liquefied natural gas burning, and liberated heat is big, so liquefied natural gas is a kind of The more advanced energy.
But in LNG ship oceangoing ship, tank car transportation and LNG filling, uninstall process, due to environment temperature and low temperature Heat transfer caused by the huge temperature difference between LNG, the precooling of station system and other reasons, the LNG of low temperature can be continuous It is heated to produce boil-off gas (abbreviation BOG).Although storage LNG low-temperature (low temperature) vessel has heat insulation layer, but still can not avoid outer heat Influence, cause produce BOG, BOG increase cause system pressure rise, once pressure exceed storage tank allow work pressure Power is, it is necessary to start safety guard release BOG decompressions.
The methane gas that existing methane gas way of recycling includes gasification to come out is through with entering city after air heat-exchange These methane gas are become CNG (pressure is more than 20MPa methane gas product) by pipe network using compressor.Into city Pipe network scheme needs LNG filling stations to common LNG filling stations and not applied to close to urban pipe network;Make CNG product market prices It is worth relatively low, accumulating is complicated, and compression power consumption is higher, and equipment is taken up an area larger.Also have and methane is cooled down using low-temperature receivers such as liquid nitrogen, weight It is new to be changed into low temperature methane liquid reuse, but this method need to be separately provided cold generation device, investment and operation power consumption are higher, stream Journey is complicated and occupation of land is larger, and the cost of the methane of recovery is higher, and the rate of recovery is low, causes the waste of the energy to a certain extent.
In order to overcome above mentioned problem, there is a kind of small-sized re-liquefied recovery of prizing liquefied natural gas boil-off gas in the prior art The mounting structure of device, including:Low-temperature storage tank, regenerating type low-temperature refrigerator, condensing heat exchanger;Condensing heat exchanger is arranged on backheat The cold end of formula Cryo Refrigerator;Boil-off gas transfer passage is provided between low-temperature storage tank and condensing heat exchanger and liquefaction is natural Gas transfer passage;Liquefied natural gas at condensing heat exchanger can enter along liquefied natural gas transfer passage under gravity Low-temperature storage tank.Although above-mentioned document improves re-liquefied efficiency, ensure that equipment operational reliability and security, but described time Heating type low-temperature refrigeration machine and condensing heat exchanger are necessarily mounted at the top of the low-temperature storage tank, therefore being provided with for equipment Certain requirement, being not easy to realize effectively reduces I&M cost;In addition, the rate of recovery of gas does not increase substantially.
The content of the invention
Therefore, the technical problems to be solved by the invention be to overcome in the prior art reclaim methane I&M into The problem of this height and the low rate of recovery, is low so as to provide a kind of I&M cost of not only equipment, and the first that the rate of recovery is high The recovery system and recovery method of alkane gas.
In order to solve the above technical problems, a kind of methane gas recovery system of the present invention, the system include flash vessel, The air inlet of the flash vessel is used to receive methane gas, and the gas outlet of the flash vessel is connected with the air inlet of compressor, institute The gas outlet for stating compressor is connected with cooling device, and the cooling device is connected to the backflow of the flash vessel by choke valve Mouthful.
In one embodiment of the invention, the liquid outlet of the flash vessel is connected with finished pot.
In one embodiment of the invention, force (forcing) pump is provided between the flash vessel and the finished pot.
In one embodiment of the invention, the cooling device is water-cooling apparatus.
In one embodiment of the invention, the cooling device is air-cooling device.
In one embodiment of the invention, the cooling device is heat exchanger, and it is logical that the heat exchanger includes at least two Road, one of passage and the flash vessel are to the pipeline connection between the compressor, another passage and the compressor Pipeline connection between to the choke valve.
In one embodiment of the invention, the air inlet of the flash vessel is connected with surge tank, the sudden strain of a muscle by pipeline Steaming device receives the methane gas by the surge tank.
In one embodiment of the invention, pressure-reducing valve is provided between the surge tank and the flash vessel.
In this one embodiment of the present of invention, each part for forming the methane gas recovery system is installed on a chassis jointly On, form skid integral structure.
Present invention also offers a kind of methane gas recovery method, and for reclaiming methane gas and collecting methane liquid, its step is such as Under, including:Step S1:The methane gas is compressed to form high pressure methane gas;Step S2:The high pressure methane gas is carried out It is cooled into high pressure low temperature methane gas;Step S3:The high pressure low temperature methane gas is throttled, forms gaseous methane and liquid The mixture of methane;Step S4:The mixture of the gaseous methane and liquid methane is separated, gaseous methane is returned and walked Rapid S1 carries out circular treatment;Liquid methane is reclaimed.
In another embodiment of the present invention, before the step S1, in addition to step S0:The methane gas that will be reclaimed Body is collected buffering, when the methane gas of collection reaches the first predetermined amount, performs the step S1-S4;And in collection When methane gas is less than the second predetermined amount, stop performing the step S1-S4.
In another embodiment of the present invention, in the step S2, by the high pressure-temperature methane gas and the step Methane gas before being compressed in S1 carries out heat exchange to complete to cool down.
The above-mentioned technical proposal of the present invention has advantages below compared with prior art:
Methane gas recovery system of the present invention and recovery method, utilize the low temperature feature for diffusing methane gas itself The possessed high-grade cold energy, the flow of gas recovery is simple, reduces the recovery power consumption of methane, and cost is low, and reclaims Product is that liquefied natural gas can be with market goods locally.
Brief description of the drawings
In order that present disclosure is more likely to be clearly understood, specific embodiment and combination below according to the present invention Accompanying drawing, the present invention is further detailed explanation, wherein
Fig. 1 is the embodiment of the present invention one and the methane gas recovery system schematic diagram described in embodiment two;
Fig. 2 is the methane gas recovery system schematic diagram described in the embodiment of the present invention three;
Fig. 3 is the methane gas recovery system schematic diagram described in the embodiment of the present invention four;
Fig. 4 is the top view in methane gas recovering device of the present invention.
Embodiment
Embodiment one:
As shown in figure 1, present embodiments providing a kind of methane gas recovery system, the system includes flash vessel 12, described The air inlet of flash vessel 12 is used to receive methane gas 10, and the gas outlet of the flash vessel 12 is connected with the air inlet of compressor 14 Connect, the gas outlet of the compressor 14 is connected with cooling device, and the cooling device is connected to the sudden strain of a muscle by choke valve 15 The refluxing opening of steaming device 12.
Above-mentioned is core technology scheme of the present invention, and methane gas recovery system of the present invention includes being used to receive The flash vessel 12 of methane gas 10, wherein, the air inlet of the flash vessel 12 is used to receive methane gas 10, and the methane gas enters to dodge After in steaming device 12, low-temp low-pressure methane gas and methane liquid are separated into;The gas outlet of the flash vessel 12 and the compressor 14 Air inlet is connected, and the methane gas isolated in the flash vessel 12 is pressed to form into high pressure-temperature methane gas, the compressor 14 gas outlet is connected with cooling device, institute's high pressure-temperature methane gas is formed high pressure low temperature methane gas after cooling, described Cooling device is connected to the refluxing opening of the flash vessel 12 by the choke valve 15, makes the high pressure low temperature methane gas through decompression The mixture of the mixture of formation gaseous methane and liquid methane after processing, the methane gas and liquid methane enters the flash distillation Low-temp low-pressure methane gas and methane liquid are separated into device 12;Wherein, the flash vessel 12, the compressor 14 and the cooling dress Put and the choke valve 15 forms gas circulation channel A, the low-temp low-pressure methane gas isolated out of described flash vessel 12 exists Constantly circulated in gas circulation channel A, the liquid outlet outflow methane liquid of the flash vessel 12 can form liquids recovery passage B, institute The methane liquid for stating separation in flash vessel 12 flows out from liquids recovery passage B.Gas circulation channel A of the present invention setting makes The low temperature methane gas constantly discharged from the gas outlet of the flash vessel 12 can be recycled, and effectively improves energy utilization rate, avoids Energy waste, reduces recovery power consumption;It is sharp that the setting of the liquids recovery passage B enables methane liquid finished product directly to collect again With so as to improve energy utilization rate;Furthermore present invention process flow is simple, skid integral type, investment and operation can be made Small power consumption, recovery product are that liquefied natural gas can reduce methane recovery power consumption, therefore not only reclaim methane gas with market goods locally Efficiency increases substantially, and reduces I&M cost.
In the present embodiment, the liquid outlet of the flash vessel 12 is connected with finished pot 16, the liquid outlet of the flash vessel 12 It is connected to form liquids recovery passage B with the finished pot 16, methane liquid finished product is passed straight back to the finished pot 16 In, so as to avoid finished pot diffuse cause reduce fluid temperature the problem of.
Illustrate the operation principle of methane gas recovery system below:
The methane gas enters in the flash vessel 12, and the operative liquid methane carried in methane gas can be in flash vessel 12 It is interior by initial gross separation, liquid methane is sent back to finished pot, and the low-temp low-pressure methane gas isolated out of described flash vessel 12 is entered Enter in the compressor 14, form high pressure methane gas by compressor compresses, the high pressure methane gas is by the cooling device High pressure low temperature methane gas is formed after cooling, then the throttling action by the choke valve 15, wherein methane gas volumetric expansion become The gaseous methane of low-temp low-pressure, because methane can absorb most of heat in expansion process, so that methane becomes liquid, Form the mixture of gaseous methane and liquid methane.The mixture of the gaseous methane and liquid methane is back to the flash vessel In 12, methane gas and methane liquid are separated into the flash vessel 12, the methane gas is arranged from the gas outlet of the flashed vapour 12 Go out to carry out circular treatment;The methane liquid isolated is discharged from the liquid outlet of the flash vessel 12, passes through liquids recovery passage B Complete the recovery of methane liquid.
Embodiment two:
As shown in figure 1, embodiment two is the improvement made on the basis of embodiment one, in order to improve recovery methane gas System, the equipment that recycling is added in the system of embodiment one, the following detailed description of:
In the present embodiment, the cooling device is heat exchanger 13, and the heat exchanger 13 includes at least two passages, wherein one Individual passage and the flash vessel 12 are to the pipeline connection between the compressor 14, another passage and the compressor 14 to institute State the pipeline connection between choke valve 15, the low temperature methane gas and the height after pressurization that the outlet side of the flash vessel 12 is constantly discharged Warm methane gas is exchanged heat, and advantageously reduces energy loss.
The air inlet of the flash vessel 12 is connected with the surge tank 11 by pipeline, and the flash vessel 12 passes through described slow Rush tank 11 and receive the methane gas 10, the present invention diffuses the recovery of methane due to can apply to LNG filling stations, make use of LNG Filling station diffuses the pressure feature of methane gas, and the setting of the surge tank 11 can overcome the unstable of LNG filling station source of releases Property, increase the time of the system each run.
Methane gas recovery system describes operation principle in detail in 1 below in conjunction with the accompanying drawings:
The surge tank 11 collects the methane gas 10 flowed into it by pipeline, when the methane gas that surge tank 11 is collected reaches When a certain amount of, the low-temp low-pressure methane gas in the surge tank 11 enters in the flash vessel 12, at the same time opens compressor 14, the operative liquid methane carried in methane gas can be sent back to finished pot in flash vessel 12 by initial gross separation, liquid methane 16, the low-temp low-pressure methane gas isolated out of described flash vessel 12 enters the heat exchanger 13, and the methane gas of low-temp low-pressure exists Carry out entering in the compressor 14 after heat exchange heating in the heat exchanger 13, the methane gas of low-voltage high-temperature passes through the pressure High pressure methane gas is formed after the pressurization of contracting machine 14, pressure is 8MPa and temperature raises, and high pressure-temperature methane enters the heat exchanger 13 exchange heat with the low-pressure low-temperature methane gas that the gas outlet of flash vessel 12 is discharged, fully the high pressure low temperature methane gas after heat exchange It is changed into the low-pressure low-temperature methane gas and methane liquid of lower 83 DEG C of zero temperature by the throttling action decompression cooling of the choke valve 15 Mixture, in the straight flash vessel 12 of mixture backflow of the low-pressure low-temperature methane gas and methane liquid, the flash vessel 12 The low-pressure low-temperature methane gas and methane liquid are separated, wherein from the gas outlet of the flashed vapour, discharge is followed methane gas Ring processing;The methane liquid isolated enters in LNG finished pots 16, and the recovery of methane liquid is completed by liquids recovery passage B.
Embodiment three:
As shown in Fig. 2 embodiment three is the deformation made on the basis of embodiment two, in order to improve recovery methane gas System, the equipment that recycling is added in the system of embodiment two, the following detailed description of:
Valve can be set between the surge tank 11 and the flash vessel 12, the valve is preferably pressure-reducing valve 17, so that Temperature can be further reduced after methane gas decompression, the cold methane gas of high-quality is supplied to the flash vessel 12, is advantageous to first Separation of the alkane gas in the flash vessel 12, the low-temp low-pressure methane gas in the surge tank 11 are decompressed to through the pressure-reducing valve 17 0.1MPa enters in the flash vessel 12, is advantageous to the flash vessel 12 and carries out obtaining more methane liquid during gas-liquid separation.
Force (forcing) pump 18 is provided between the flash vessel 12 and the finished pot 16, for by methane liquid in the flash vessel 12 Body is evacuated in the finished pot 16, is advantageous to the methane liquid stream and is entered in the finished pot 16, is easy to recycle.
In the present embodiment, the cooling device is water-cooling apparatus, and the exit of the compressor 14 is provided with water cooling system System 19, for the methane air cooling after compression, the water cooling system 19 to be included into upper circulation water 191 and lower recirculated water 192. In gas circulation channel A, the low-temp low-pressure methane gas isolated in the flash vessel 12 enters the heat exchanger 13, and low temperature is low The methane gas of pressure enters in the compressor 14 after carrying out heat exchange heating in the heat exchanger 13, when low-pressure methane passes through The compressor 14 forms high pressure methane gas after pressurizeing, pressure is 8MPa and temperature raises, and is carried out through the water cooling system 19 Cooling, normal temperature is cooled to by the high pressure-temperature methane gas that the compressor 14 exports, specifically, by common with the compressor 14 Upper circulation water 191 and lower recirculated water 192 to high pressure methane gas so as to cool, the methane gas after now high pressure cooling It is more beneficial for exchanging heat with the low-pressure low-temperature methane gas of the gas outlet of flash vessel 12 discharge into the heat exchanger 13, fully subtracts Required energy during small heat exchange, the high pressure low temperature methane gas after heat exchange is by the choke valve 15 expansion decompression cooling It is changed into the low-pressure low-temperature methane gas of lower 85 DEG C of zero temperature and the mixture of methane liquid, the low-pressure low-temperature methane gas and methane liquid Mixture enter in the flash vessel 12, the flash vessel 12 is by the mixture of the low-pressure low-temperature methane gas and methane liquid point From into methane gas and recyclable methane liquid.
Deformed as one kind, this implementation cooling device may be alternatively provided as air-cooling device, and the compressor 14 goes out Water air-cooling device is provided with mouthful, the methane gas after compression can equally be cooled.
In the present embodiment, the storage capacity of surge tank 11 is equal to system hour disposal ability.
Example IV:
As shown in figure 3, example IV is the deformation made on the basis of embodiment three, in order to improve recovery methane gas System, the monitoring device for controlling gas to reclaim automatically is added in the system of example IV, the following detailed description of:
Pressure-reducing valve 17 described in the present embodiment is pressure self-adjusting valve, and the pressure self-adjusting valve, which is provided with, controls the pressure certainly The pressure monitoring device 171 for adjusting valve and compressor 14 to open and close, when the pressure of the surge tank 11 reaches 0.6MPa described in unlatching Pressure self-adjusting valve, the low-temp low-pressure methane in surge tank 11 are decompressed to 0.15MPa through the pressure self-adjusting valve and enter the flash distillation In device 12, more methane liquid are obtained so as to be advantageous to separation of the methane gas in the flash vessel 12.In the flash vessel 12 The low-temp low-pressure methane gas isolated enters the heat exchanger 13, and the methane gas of low-temp low-pressure is changed in the heat exchanger 13 Enter after heat heating in the compressor 14, high pressure methane is formed after low-pressure methane is pressurizeed by the compressor 14 Gas, pressure is 8.5MPa and temperature raises, and is cooled through the water cooling system 19, and the methane gas after high pressure cooling enters institute State and be more beneficial for exchanging heat with the low-pressure low-temperature methane gas of the gas outlet of flash vessel 12 discharge in heat exchanger 13, so as to reduce energy High pressure low temperature methane gas after loss, fully heat exchange expands decompression cooling transformation by the throttling action of the choke valve 15 The mixture of low-pressure low-temperature methane gas and methane liquid for lower 90 DEG C of zero temperature, is advantageous to enter the 12 laggard promoting the circulation of qi of flash vessel Liquid separates.
The flash vessel 12 is provided with the level monitoring device 121 that control force (forcing) pump 18 opens and closes, the force (forcing) pump 18 and institute State and be provided with liquid level self-adjusting valve 122 between finished pot 16, the level monitoring device 121 controls the force (forcing) pump 18 and the liquid The unlatching of position self-adjusting valve 122 or closure, specifically, the liquid level monitoring arrangement 121 detect the inside of flash vessel 12 When liquid height exceedes preset value, the liquid level self-adjusting valve 122 and the force (forcing) pump 18 are may turn on, utilizes the force (forcing) pump 18 Liquid pressing is entered in the finished pot 16.Device for detecting temperature is provided between the heat exchanger 13 and the compressor 14 20, the temperature for monitoring methane gas ensures that the trouble-free operation of system, including detection export what is flowed out from the heat exchanger 13 Methane gas temperature and the methane gas temperature for flowing to the entrance of compressor 14.
In the present embodiment, the storage capacity of surge tank 11 is more than system hour disposal ability.
Embodiment five:
The present embodiment provides a kind of methane gas recovery method, utilizes embodiment one, embodiment two, embodiment three, embodiment Four any one of methane gas recovery system recovery methane gas and collection methane liquid, its step is as follows:Step S1:By institute Methane gas is stated to be compressed to form high pressure methane gas;Step S2:The high pressure methane gas is carried out being cooled into high pressure low temperature first Alkane gas;Step S3:The high pressure low temperature methane gas is throttled, forms the mixture of gaseous methane and liquid methane;Step S4:The mixture of the gaseous methane and liquid methane is separated, gaseous methane return to step S1 is subjected to circular treatment; Liquid methane is reclaimed.
In methane gas recovery method described in the present embodiment, the low temperature methane constantly discharged from the gas outlet of the flash vessel 12 Gas can be recycled, and effectively improve energy utilization rate, avoid energy waste, reduce recovery power consumption;The methane liquid finished product It can be passed straight back in the finished pot 16, recovery process is simple, and cost is low, and it is that liquefied natural gas can be just to reclaim product Sell on ground.
In the present embodiment, also include step S0 before the step S1:The methane gas that will be reclaimed is collected buffering, When the methane gas of collection reaches the first predetermined amount, the step S1-S4 is performed, ensures a system run time as far as possible It is longer, avoid frequently opening;And when the methane gas of collection is less than the second predetermined amount, stops performing the step S1-S4, have Effect avoids problem of being felt suffocated in the flash vessel 12.
In the step S2, the methane gas before being compressed in the high pressure-temperature methane gas and the step S1 is carried out Heat exchange is completed to cool down, and can not only effectively improve energy utilization rate, and advantageously reduce energy loss.
The storage capacity of surge tank 11 can make methane gas constantly automatic when being more than or equal to system hour disposal ability Recovery, so as to be easily achieved the market goods locally of liquefied natural gas.
Embodiment six:
The present embodiment provides a kind of methane gas recycling and control method, using described in embodiment two, embodiment three, example IV Any one methane gas recovery system recovery methane gas, including:
Step S1:The methane gas that will be reclaimed is collected buffering, and the pressure is controlled certainly using pressure monitoring device The keying of valve is adjusted, when the methane gas of collection reaches the first predetermined amount, the pressure self-adjusting valve is opened, into step S2; When the methane gas of collection is less than the second predetermined amount, the pressure self-adjusting valve is closed, continues collection methane gas to methane gas and reaches To first predetermined amount, the pressure self-adjusting valve is opened, into step S2;Step S2:Start compressor, by the methane gas It is compressed to form high pressure methane gas;Step S3:The high pressure methane gas is carried out being cooled into high pressure low temperature methane gas;Step S4:The high pressure low temperature methane gas is throttled, forms the mixture of gaseous methane and liquid methane;Step S5:By described in The mixture of gaseous methane and liquid methane is separated, and gaseous methane return to step S2 is carried out into circular treatment;By liquid first Alkane is reclaimed.
Methane gas recycling and control method described in the present embodiment, pressure is provided between the surge tank 11 and the flash vessel 12 Detection means 171, the pressure-detecting device 171 can enter to the motor switch of the pressure-reducing valve 17 and the compressor 14 Row interlocked control, be advantageous to extension system separate run times, now the pressure-reducing valve 17 is pressure self-adjusting valve.This method passes through The pressure of the surge tank 11 is monitored to judge whether to open recovery system, once the pressure of the surge tank 11 is pre- higher than first If amount is pressure high-value, the pressure self-adjusting valve is opened, whole system automatically turns on, the methane gas in the surge tank 11 Respectively enter in the gas circulation channel A and the liquids recovery passage B;If the pressure of the surge tank 11 is pre- less than second If amount is pressure low-value, the pressure self-adjusting valve is closed, continues to collect methane gas to methane gas that to reach described first pre- If untill amount, the pressure self-adjusting valve, activation system are opened.Furthermore control method of the present invention is controlled by pressure interlock The keying of system, be advantageous to extension system separate run times, avoid controlling using manpower, solve the automation of methane recovery Control problem, so not only having saved human cost but also having reduced inoperative power cost.
In the present embodiment, the setting of the pressure low-value is considered based on the pressure requirements that follow-up system is run, if pressure Too low, the methane gas in the surge tank 11 will be difficultly flowed into the flash vessel 12, easily be felt suffocated;The pressure is high The pressure in the source of methane gas 10 is diffused in the setting of place value based on leading portion, and methane source gas is diffused when the pressure high-value is higher than Collected during pressure, in the surge tank 11 it is enough diffuse methane gas, to ensure that the storage capacity of surge tank 11 is big In equal to system hour recovery ability so that a system run time as far as possible is longer, avoids frequently opening.If the buffering When the pressure of tank 11 is less than pressure low-value, whole system is closed, if the pressure of the surge tank 11 is higher than pressure high-value, Whole system is opened, specifically, when the pressure of the surge tank 11 is less than 0.1Mpa-0.3Mpa, halt system operation, preferably It is 0.2Mpa for the pressure low-value, halt system is run;Opened when the pressure of surge tank 11 is higher than 0.5Mpa-0.7Mpa System, preferably described pressure high-value are 0.6Mpa open systems.
In order to improve the automatic recovery of methane gas, in the present embodiment, the exit of flash vessel 12 and the compressor 14 Device for detecting temperature 20 is provided with inlet duct, wherein, the device for detecting temperature 20 is provided with temperature alarming high-value and temperature Stop high-value.When the temperature detected is higher than temperature alarming high-value, whether system automatic alarm, detecting system normally transports OK;When the temperature detected is higher than parking high-value, the pressure self-adjusting valve and the compressor 14 are closed, system is stopped automatically Car.The device for detecting temperature 20 is used to carry out interlocked control to the motor of the pressure self-adjusting valve and the compressor 14, Be advantageous to monitor the heat exchanger 13 and the compressor 14 whether normal operation, not only can effective monitoring running situation, And essential safety can be accomplished.Wherein, it is by monitoring the entrance methane of compressor 14 the purpose of design temperature alarm high-value The temperature of gas, the heat exchanger 13 as described in temperature too high possible display breaks down or the compressor 14 exports methane gas Temperature is too high, influences overall operation.Methane gas temperature between the heat exchanger 13 and the compressor 14 is higher than temperature alarming During high-value, system automatic alarm;Methane gas temperature between the heat exchanger 13 and the compressor 14 is high-order higher than parking During value, system automatic stopping.Specifically, the entrance methane gas temperature of the compressor 14 is if above 10 DEG C -30 DEG C, and system is certainly Dynamic alarm, the entrance methane gas temperature of preferably described compressor 14 is if above 15 DEG C, and system is with regard to automatic alarm;The heat exchange If the Outlet Gas Temperature of device 13 is higher than 20 DEG C -40 DEG C, system automatic stopping, the exit gas of preferably described heat exchanger 13 If temperature is higher than 30 DEG C, system automatic stopping.When actual process is set, temperature parking high-value is high-order higher than temperature alarming Value.
For the automatic recovery of constantly improve methane gas, in the present embodiment, the flash vessel 12 is provided with liquid level detection device 121, liquid level self-adjusting valve 122 is provided between the force (forcing) pump 18 and the finished pot 16.The liquid level detection device 121 is provided with Liquid level high-value and liquid level low-value, after the methane gas is separated into methane liquid in the flash vessel 12, examined by liquid level The liquid level that device 121 detects methane liquid is surveyed, when the liquid level of the methane liquid detected is higher than liquid level high-value, starts force (forcing) pump 18, methane liquid is transported in finished pot 16;When the liquid level of the methane liquid detected is less than liquid level low-value, force (forcing) pump is closed 18, the present embodiment to motor switch on the force (forcing) pump 18 and the liquid level self-adjusting valve 122 by carrying out interlocked control, so as to have Beneficial to the separate run times for extending the force (forcing) pump 18, avoid the problem of full liquid note does not enter gas in the flash vessel 12 or Liquid level too low the problem of causing gas to seal in force (forcing) pump 18.
In the present embodiment, the setting of the liquid high-value is run based on total system, if storing enough methane liquid again The frequent unlatching of the force (forcing) pump 18 can be avoided by opening the force (forcing) pump 18, if the liquid level in the flash vessel 12 is high higher than liquid It is too small that place value also results in the upper end gas compartment of flash vessel 12, causes air pressure in the flash vessel 12 to raise, if be higher than into When entering the methane gas pressure of the flash vessel 12, it can cause to carry out gas to cannot be introduced into, easily cause and feel suffocated;The liquid low-value Once setting be based on consider liquid level it is relatively low, the methane gas in the flash vessel 12 may be mixed into methane liquid and enter finished pot 16 In.In order to which the methane liquid for ensureing to isolate from the flash vessel smoothly can enter in liquids recovery passage B, the flash vessel 12 Interior liquid level starts the force (forcing) pump 18 when being higher than liquid level high-value, if the liquid level in the flash vessel 12 is less than liquid level low-value When, close the force (forcing) pump 18.Specifically, when the liquid level on the flash vessel 12 reaches the general assembly liquid height of flash vessel 12 During 60%-80%, start the force (forcing) pump 18, and open the liquid level self-adjusting valve 122, preferably described liquid level high-value is institute State 70% of general assembly liquid height in flash vessel 12;When the liquid level on the flash vessel 12 is less than 10%-30%, described add is closed Press pump 18 and the liquid level self-adjusting valve 122, preferably described liquid level low-value are the 20% of the general assembly liquid height of flash vessel 12.
Also include tentatively dividing the liquid methane carried in methane gas in the present embodiment, between the step S1 and S2 From the liquid methane isolated is delivered into finished pot 16, methane gas is transported into compressor 14, performs step S2.
In the present embodiment, the storage capacity of surge tank 11 can make methane gas when being more than or equal to system hour disposal ability Constantly automatic recovery, so as to be easily achieved the market goods locally of liquefied natural gas.
Embodiment seven:
As shown in figure 4, methane gas recovery system of the present embodiment according to embodiment three or example IV provides one Kind methane gas recovering device, the retracting device are made package unit, and each part for forming the methane gas recovery system is pacified jointly Loaded on a chassis, skid integral structure is formed, so as to ensure that operational reliability and security, specific size can be according to reality The design of border service requirement, if skid body is 10 meters * 6 meters * 2.5 meters, wherein a length of 10 meters, a width of 6 meters, a height of 2.5 meters, wherein, The distance of wall vertically is 2m in the surge tank 11 to skid body, and wall is along level side in the surge tank 11 to skid body To distance be 1.8m, the distance of the surge tank 11 to the flash vessel 12 vertically is 3.5m, the flash vessel 12 To the distance of distance and the heat exchanger 13 to the compressor 14 vertically of the force (forcing) pump 18 vertically It is 3m, the distance of the flash vessel 12 to the heat exchanger 13 in the horizontal direction is 3m.
In the present invention, the source of the gas of surge tank 11 is LNG filling processes, LNG finished pots diffuse process, LNG tank cars are let out Press through journey etc..
To sum up, above technical scheme of the present invention has advantages below:
1. present invention could apply to the recovery that LNG filling stations diffuse methane, LNG filling stations make use of to diffuse methane gas Pressure feature, the setting of the surge tank can overcome the unstability of LNG filling station source of releases, increase the system each run Time;The setting of the gas circulation channel makes the low temperature methane gas constantly discharged from the gas outlet of the flash vessel and pressurization High-temperature methane gas afterwards is exchanged heat, and reduces energy loss;The setting of the liquids recovery passage enables methane liquid finished product Be passed straight back in the finished pot, so as to avoid finished pot diffuse cause reduce fluid temperature the problem of;Furthermore this hair Bright technological process is simple, can make skid integral type, investment and operation small power consumption, and recovery product is that liquefied natural gas can be just Ground is sold, and reduces methane recovery power consumption, therefore the efficiency for not only reclaiming methane gas increases substantially, and reduces installation and dimension Protect cost.
2. pressure-reducing valve is provided between surge tank of the present invention and the flash vessel, so that one can be entered after methane gas decompression Step reduces temperature, is advantageous to separation of the methane gas in the flash vessel so as to obtain more methane liquid;The flash vessel and Force (forcing) pump is provided between the finished pot, is advantageous to the methane liquid stream and enters in the finished pot, be easy to recycle;The pressure The exit of contracting machine is provided with water cooling system, is advantageous to cool to high pressure methane gas, is easy to reduce required during follow-up heat exchange The energy wanted.
3. pressure-reducing valve of the present invention is provided with the pressure monitoring device for controlling the pressure-reducing valve and compressor to open, described Pressure-detecting device can carry out interlocked control to the motor switch of the pressure-reducing valve and the compressor, be advantageous to extend system System separate run times;Device for detecting temperature, the temperature are provided with the flash vessel exit and the compressor inlet duct Spend monitoring device to be used to carry out interlocked control to the motor of the pressure-reducing valve and the compressor, be advantageous to monitor the heat exchange Device and the compressor whether normal operation, not only can effective monitoring running situation, and essential safety can be accomplished;It is described Flash vessel is provided with liquid level detection device, liquid level self-adjusting valve is provided between the force (forcing) pump and the finished pot, when the flash vessel After the interior methane gas is separated into methane liquid, liquid level detection device is opened, to motor switch on the force (forcing) pump and the liquid Position self-adjusting valve carries out interlocked control, so as to be advantageous to extend the separate run times of the force (forcing) pump, avoids the flash vessel from expiring Liquid note the problem of not entering gas or liquid level too low the problem of causing gas to seal in the force (forcing) pump.
4. in methane gas recovery method of the present invention, low temperature methane gas that the gas outlet of the flash vessel is constantly discharged with High-temperature methane gas after pressurization is exchanged heat, and energy loss can be made small, avoid energy waste, reduce recovery power consumption;Institute Stating methane liquid finished product can be passed straight back in the finished pot, and recovery process is simple, and cost is low, and reclaim product as liquefaction day Right gas can be with market goods locally.
5. methane gas recycling and control method of the present invention, in order to improve the automatic recovery of methane gas, the flash vessel goes out Be provided with device for detecting temperature at mouthful place and the compressor inlet duct, the device for detecting temperature for the pressure-reducing valve with And the motor of the compressor carries out interlocked control, be advantageous to monitor the heat exchanger and the compressor whether normal operation, Not only can effective monitoring running situation, and essential safety can be accomplished.
Obviously, above-described embodiment is only intended to clearly illustrate example, not to the restriction of embodiment.For For those of ordinary skill in the art, other various forms of changes or change can also be made on the basis of the above description It is dynamic.There is no necessity and possibility to exhaust all the enbodiments.And the obvious change or change thus extended out Move still in the protection domain of the invention.

Claims (9)

  1. A kind of 1. methane gas recovery system, it is characterised in that:The system includes flash vessel (12), and flash vessel (12) are entered Gas port is used to receive methane gas (10), and the gas outlet of the flash vessel (12) is connected with the air inlet of compressor (14), described The gas outlet of compressor (14) is connected with cooling device, and the cooling device is connected to the flash vessel by choke valve (15) (12) refluxing opening, the air inlet of the flash vessel (12) are connected with surge tank (11) by pipeline, and the flash vessel (12) is logical Cross the surge tank (11) and receive the methane gas (10), decompression is provided between the surge tank (11) and the flash vessel (12) Valve (17), the pressure-reducing valve (17) are provided with the pressure monitoring dress for controlling the pressure-reducing valve (17) and the compressor (14) keying Put (171).
  2. 2. methane gas recovery system according to claim 1, it is characterised in that:The liquid outlet of the flash vessel (12) with into Product tank (16) is connected.
  3. 3. methane gas recovery system according to claim 2, it is characterised in that:The flash vessel (12) and the finished pot (16) force (forcing) pump (18) is provided between.
  4. 4. methane gas recovery system according to claim 1, it is characterised in that:The cooling device is water-cooling apparatus (19)。
  5. 5. methane gas recovery system according to claim 1, it is characterised in that:The cooling device is air-cooling device.
  6. 6. methane gas recovery system according to claim 1, it is characterised in that:The cooling device is heat exchanger (13), The heat exchanger (13) includes at least two passages, one of passage and the flash vessel (12) to the compressor (14) it Between pipeline connection, the pipeline connection between another passage and the compressor (14) to the choke valve (15).
  7. 7. the methane gas recovery system according to any one in claim 1-6, it is characterised in that:Form the methane gas Each part of recovery system is installed on a chassis jointly, forms skid integral structure.
  8. 8. a kind of methane gas recovery method, for reclaiming methane gas and collecting methane liquid, its step is as follows, including:
    Step S1:The methane gas that will be reclaimed is collected buffering, and the keying of pressure-reducing valve is controlled using pressure monitoring device, When the methane gas of collection reaches the first predetermined amount, the pressure-reducing valve is opened,
    Into step S2;When the methane gas of collection is less than the second predetermined amount, the pressure-reducing valve is closed, continues to collect methane gas Reach first predetermined amount to methane gas, open the pressure-reducing valve, into step S2;
    Step S2:The methane gas is compressed to form high pressure methane gas;
    Step S3:The high pressure methane gas is carried out being cooled into high pressure low temperature methane gas;
    Step S4:The high pressure low temperature methane gas is throttled, forms the mixture of gaseous methane and liquid methane;
    Step S5:The mixture of the gaseous methane and liquid methane is separated, gaseous methane return to step S2 is carried out Circular treatment;Liquid methane is reclaimed.
  9. 9. methane gas recovery method according to claim 8, it is characterised in that:In the step S3, by the high pressure first Alkane gas carries out heat exchange to complete to cool down with the methane gas before being compressed in the step S2.
CN201510106834.5A 2015-03-11 2015-03-11 methane gas recovery system and recovery method Expired - Fee Related CN104696700B (en)

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US20140352331A1 (en) * 2013-05-30 2014-12-04 Hyundai Heavy Industries Co., Ltd. Liquefied gas treatment system
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