CN101899342A - Process for producing liquefied natural gas by coal bed gas in mine coal - Google Patents

Process for producing liquefied natural gas by coal bed gas in mine coal Download PDF

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CN101899342A
CN101899342A CN201010244261XA CN201010244261A CN101899342A CN 101899342 A CN101899342 A CN 101899342A CN 201010244261X A CN201010244261X A CN 201010244261XA CN 201010244261 A CN201010244261 A CN 201010244261A CN 101899342 A CN101899342 A CN 101899342A
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interchanger
gas
methane
enter
heat exchange
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CN101899342B (en
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陶鹏万
王大军
王少楠
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Southwest Research and Desigin Institute of Chemical Industry
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Southwest Research and Desigin Institute of Chemical Industry
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
    • F25J3/0209—Natural gas or substitute natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
    • F25J1/0022—Hydrocarbons, e.g. natural gas
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    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/0035—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by gas expansion with extraction of work
    • F25J1/0037—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by gas expansion with extraction of work of a return stream
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    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/004—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by flash gas recovery
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    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
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    • F25J1/0208—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using a single-component refrigerant [SCR] fluid in a closed vapor compression cycle in combination with an internal quasi-closed refrigeration loop, e.g. with deep flash recycle loop
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    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0228—Coupling of the liquefaction unit to other units or processes, so-called integrated processes
    • F25J1/0235—Heat exchange integration
    • F25J1/0237—Heat exchange integration integrating refrigeration provided for liquefaction and purification/treatment of the gas to be liquefied, e.g. heavy hydrocarbon removal from natural gas
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    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
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    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0257—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/02—Processes or apparatus using separation by rectification in a single pressure main column system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/72—Refluxing the column with at least a part of the totally condensed overhead gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/40—Air or oxygen enriched air, i.e. generally less than 30mol% of O2
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/20—Boiler-condenser with multiple exchanger cores in parallel or with multiple re-boiling or condensing streams
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2260/00—Coupling of processes or apparatus to other units; Integrated schemes
    • F25J2260/02—Integration in an installation for exchanging heat, e.g. for waste heat recovery
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    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2260/00—Coupling of processes or apparatus to other units; Integrated schemes
    • F25J2260/20—Integration in an installation for liquefying or solidifying a fluid stream
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    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/04—Internal refrigeration with work-producing gas expansion loop
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    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
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  • General Chemical & Material Sciences (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

The invention discloses a process for producing liquefied natural gas by coal bed gas in mine coal, comprising the following steps: feeding the coal bed gas in the mine coal after oxygen removal, pressurization, desulphurization, decarburization and drying treatment in a low temperature device to serve as a feed gas for low temperature separation, respectively obtaining waster nitrogen and methane gas after separation, feeding the methane gas obtained by low temperature separation in a refrigerating liquefaction plant for refrigeration and liquefaction, and obtaining the liquefied natural gas. In the process of the invention, the coal bed gas in the mine coal with a low methane content is utilized as the feed gas to produce the liquefied natural gas (LNG) with high methane content up to above 99%. The invention has simple process flow, less equipment input and maintenance cost, and can reduce power consumption of circulation and compression.

Description

A kind of technology of producing liquefied natural gas by coal bed gas in mine coal
Technical field
The invention belongs to gas delivery, the liquefaction technology field of adopting cryogenic method, particularly a kind of technology of producing liquefied natural gas by coal bed gas in mine coal.
Background technology
Coal-seam gas is the gas that is rich in methane, also is a kind of clean fuel.China's coal-seam gas is used to guarantee the safety in colliery mainly from the down-hole extraction at present.Since restrictions such as extraction technology and production technique, and the coal-seam gas that obtains (the coal field coal-seam gas, CMM) methane content is about 30%～60% (volume, down together), and concentration is not high, and changes with the variation of mining environment.Usually can be used as domestic fuel, public utilities usefulness gas and generating during the gas utilization of this kind content.But because civilian limited, generating efficiency is lower again, so the coal-seam gas of releasing mostly directly enters atmosphere, has both wasted resource, has polluted environment again, and has increased the weight of Greenhouse effect.In order to make full use of this type of coal-seam gas (CMM) resource, according to " Sweet natural gas " standard GB 17820-1999, must carry the dense methane content that arrives to the methane in this type of coal-seam gas more than 85%, export as gas product.For remote convenient transportation, producing natural gas liquids (LNG) is a kind of selection preferably.LNG requires methane purity higher, requires usually to reach more than 99%, and nitrogen content should be below 1%; Nitrogen content is higher, and meaning work LNG temperature is lower.According to " deep cooling handbook (the first volume) (chief editor of Design Academy No. 4, Ministry of Chemical Industry, fuel press published in 1973) the 277 pages of methane that provides-nitrogen system vapour-liquid biphase equilibrium composition data, under 0.2026MPa (2atm) pressure, nitrogen is 0 o'clock, and its equilibrium temperature is 120.2K (152.95 ℃); 1% the time, its equilibrium temperature is 115.2K (157.95 ℃) when nitrogenous, and the latter is lower 5 ℃ than the former, and temperature is low, institute's chilling requirement the more, energy consumption is bigger.
In order to obtain highly purified methane, the contriver is devoted to this research for many years, updates the technology of production high density methane from various coal-seam gas.The applicant promptly discloses a kind of " the coal-seam gas low ternperature separation process is carried dense methane technology " in the Chinese patent ZL 200410040155.4 that files an application in July, 2004, in the low ternperature separation process operation auxiliary circulation system that is used to improve low temperature separation unit reboiler steam output is set, condenser is gone in the methane throttling of cooling back and liquefaction in the auxiliary circulation, as the low-temperature receiver that condensation is used, can guarantee that like this methane purity brings up to 95%～99%; But the methane of this concentration range can't satisfy the requirement as natural gas liquids (LNG).
Only have in the world at present and from the coal-seam gas of methane content higher (～67%), separate the industrialized unit that obtains about 96% purity methane, still separate obtaining methane content and require in the coal field coal-seam gas of methane content lower (content is more than 35%) of having no way of, can't from the lower low-quality coal-seam gas of methane content, separate obtaining liquefied methane product (LNG) according to prior art at the industrialized unit of the liquefied natural gas product more than 99% (LNG) and the report of related process.
Summary of the invention
Main purpose of the present invention is can't separate the higher liquefied methane product problems such as (LNG) of methane content that obtains at what exist in the above-mentioned prior art from the lower low-quality coal-seam gas such as coal field coal-seam gas of methane content, providing a kind of is the technology of raw material production natural gas liquids with the lower coal field low-quality coal-seam gas of methane content, can the lower coal field coal-seam gas of methane content be raw material, make methane content and reach natural gas liquids LNG more than 99%.
In order to realize the foregoing invention purpose, the technical solution used in the present invention is as follows:
A kind of technology of producing liquefied natural gas by coal bed gas in mine coal:
The coal field coal-seam gas enters cryogenic unit as unstripped gas and carries out low ternperature separation process after deoxygenation, pressurization, desulfurization, decarburization and drying; After the cooling, the reboiler that enters rectifying tower is as the evaporation thermal source, and cooling in first interchanger, enter again that second interchanger further cools off, throttling, enter rectifying tower, under the refinery distillation of rectifying tower, cat head obtains useless nitrogen, discharger after interchanger reclaims the cold re-heat; The tower still obtains liquid methane, and throttling is gone into overhead condenser as low-temperature receiver; The methane of evaporation is after interchanger reclaims the cold re-heat, as gases methane output cryogenic unit;
Wherein:
In the low ternperature separation process operation, be provided for improving the auxiliary circulation of the steam output of rectifying tower reboiler, be throttled to a higher intermediate pressure by refrigeration system high pressure methane, extract a certain amount of not liquefied methane out and enter the rectifying tower reboiler as the evaporation thermal source, the methane liquefaction that is cooled, the low intermediate pressure of throttling to again, enter first interchanger and cool off into tower coal-seam gas, and then turn back to the corresponding position of refrigeration system; Cat head evaporates, the gases methane after re-heat is sent into refrigeration system again, carries out refrigeration liquefying and obtains liquid methane, promptly can be used as natural gas liquids output.
Higher intermediate pressure in the above-mentioned low ternperature separation process operation is for being higher than more than the rectifying tower pressure 0.2MPa; Low intermediate pressure is 0.3MPa～0.45MPa.
In the low ternperature separation process operation, the liquid methane that rectifying Tata still obtains, the methane of available cat head evaporation cross cold after again throttling go into overhead condenser.
In the refrigeration liquefying operation, can adopt the liquefaction cycle of the high pressure methane second throttle that has precooling, or have the rear methane expansion cycles of precooling, refrigeration agent is a methane.
In the cryogenic unit, can provide the liquid methane of 0.3MPa～0.45MPa as low-temperature receiver by refrigeration system.
As preferred version more specifically, in the above-mentioned technology of the present invention,
The low ternperature separation process operation comprises:
A, unstripped gas enter cryogenic unit, cool off by the first interchanger heat exchange;
B, enter the 4th interchanger in rectifying tower (low-temperature fractionating tower) reboiler,, in the heating tower bottoms, self be cooled as the evaporation thermal source of tower bottoms;
C, enter the further heat exchange of second interchanger cooling again;
D, through the throttling step-down, enter rectifying tower then, under the refinery distillation of rectifying tower, separate, cat head obtains useless nitrogen, the tower still obtains liquid methane (in volumn concentration, the purity of liquid methane can reach more than 99.0%);
The useless nitrogen that E, rectifying tower cat head obtain reclaims cold re-heat discharger to the normal temperature through second interchanger, first interchanger respectively;
The liquid methane that F, rectifying Tata still obtain, cold excessively through the 3rd interchanger, again after the throttling step-down, the condenser that enters the rectifying tower cat head can increase the condenser cold as low-temperature receiver, increases to reflux; The methane gas of evaporation reclaims the cold re-heat to normal temperature through the 3rd interchanger, first interchanger respectively, as gases methane output cryogenic unit, enters refrigeration system and carries out next step refrigeration liquefying operation.
In the step e wherein, the useless nitrogen that the rectifying tower cat head obtains, after reclaiming cold through the second interchanger heat exchange, also can be by the decompressor step-down of expanding, reclaim cold re-heat discharger to the normal temperature by the further heat exchange of first interchanger again.
The refrigeration liquefying operation comprises:
G, the gases methane of exporting from cryogenic unit enter refrigeration plant, carry out the compression of 3-5 level by compressor;
H, go out behind the compressor respectively through the 7th interchanger, the 6th interchanger, the 8th interchanger heat exchange cooling;
I, through the throttling step-down, enter first gas-liquid separator then and carry out the gas-liquid separation first time, obtain not liquefied gas and liquid methane respectively;
J, the not liquefied gas that first gas-liquid separator is obtained are divided into two portions;
J1, first part enter cryogenic unit, in the 5th interchanger in the rectifying tower reboiler of cryogenic unit, as the evaporation thermal source of tower bottoms, self are cooled and liquefy in the heating tower bottoms; Through the throttling step-down, again by second interchanger heat exchange gasification; Return refrigeration system then, with from step L after the gasification methane blended after the 9th interchanger re-heat, respectively by the 8th interchanger and the 7th interchanger heat exchange, re-heat to normal temperature, enter compressor again, mix with gases methane, enter the next stage compression jointly from cryogenic unit; This part not liquefied gas circulation can make compression ratio reduce, thus the save compressed power consumption;
J2, second section respectively by the 8th interchanger and the 7th interchanger heat exchange, re-heat to normal temperature, enter compressor again, mixes with other gas in the compressor, enter next stage jointly and compress;
K, the liquid methane that is obtained by first gas-liquid separator are cold excessively through the 9th interchanger heat exchange; Again through the throttling step-down; Enter second gas-liquid separator then and carry out the gas-liquid separation second time, methane (on a small quantity) and liquid methane obtain respectively gasifying;
L, the gasification methane that obtains by second gas-liquid separator, through the 9th interchanger heat exchange, when crossing the liquid methane that cold first gas-liquid separator obtains, self is by re-heat; Mix by the cooled gas of the second interchanger heat exchange again with from step J1, pass through the 8th interchanger and the 7th interchanger heat exchange, re-heat then respectively, enter compressor again to normal temperature;
M, the liquid methane purity that is obtained by second gas-liquid separator can reach more than 99%, promptly can be used as natural gas liquids (LNG) output.
Among the step J2 wherein, second section in the not liquefied gas that obtains by first gas-liquid separator, after the 8th interchanger heat exchange, also can be by the decompressor step-down of expanding, again with from step J1 by the cooled gas of the second interchanger heat exchange and from step L after the 9th interchanger re-heat the gasification methane blended, pass through the 8th interchanger and the 7th interchanger heat exchange, re-heat then respectively to normal temperature, enter compressor again.
In the step K wherein, after second gas-liquid separator carries out the gas-liquid separation second time, the liquid methane that obtains can be extracted a part, after throttling, pass through the second interchanger heat exchange of cryogenic unit, be used for replenishing cold, the further unstripped gas that cools off from rectifying tower reboiler the 4th interchanger, self be heated simultaneously; Return refrigeration system then, with from step J1 by the cooled gas of the second interchanger heat exchange and from step L after the 9th interchanger re-heat the gasification methane blended, pass through the 8th interchanger and the 7th interchanger heat exchange, re-heat respectively to normal temperature, enter compressor again.
In the technology of the present invention, in refrigeration cycle, high pressure methane is throttled to a higher intermediate pressure (more than the high 0.2MPa of rectifying tower pressure), extracting one gases methane that does not liquefy out goes rectifying tower still reboiler to make the evaporation thermal source, itself is liquefied, (0.30MPa～0.45Mpa) remove to cool off high pressure CMM, itself is heated, and then gets back to the corresponding position of refrigeration system to be throttled to low intermediate pressure again.Compression ratio is reduced, thus the save compressed power consumption; Secondly, with tower still methane cross cold after again throttling go into the tower condenser, can increase tower condenser cold like this, increase and reflux.In addition, when the nitrogen that need not give up expands, adopt a part of LNG to replenish as cold, need be less because separate cold, can simplify flow process like this.
Compared with prior art, the invention has the beneficial effects as follows:
Adopting technology of the present invention, is unstripped gas with the lower coal field coal-seam gas of methane content, can produce to make methane content and reach natural gas liquids LNG more than 99%.And, in this technological process, from the not liquefied gas that first gas-liquid separator separates of refrigeration liquefying device obtains, tell the methane gas of a part of higher intermediate pressure and remove the rectifying tower of cryogenic unit, thermal source heating tower bottoms as reboiler, be throttled to 0.30MPa～0.45MPa pressure again and go to cool off high pressure feed, can save the rectifying tower heating and need ad hoc auxiliary circulating equipment usually, and refrigeration plant that usually need be ad hoc in the cryogenic unit and refrigeration agent etc., and low ternperature separation process does not partly have movable machinery, make the flow process of whole technology simple, equipment input and maintenance cost are few, also can reduce power consumption of circulation and compression, cut down the consumption of energy etc.
Description of drawings
Fig. 1 is the process flow diagram of the embodiment of the invention 1;
Fig. 2 is the process flow diagram of the embodiment of the invention 2;
Fig. 3 is the process flow diagram of the embodiment of the invention 3.
Among Fig. 1-3, each mark is represented respectively: E1～E9 is respectively first～the 9th interchanger, T is a rectifying tower, C is the condenser of rectifying tower cat head, and R is a vaporizer, and EXP is a decompressor, COP is a compressor, V1 is first gas-liquid separator, and V2 is second gas-liquid separator, and 1-17,21-44 are respectively the pipeline of different sections.
Embodiment
Below in conjunction with embodiment foregoing invention content of the present invention is described in further detail.
But this should be interpreted as that the scope of the above-mentioned theme of the present invention only limits to following embodiment.Not breaking away under the above-mentioned technological thought situation of the present invention, according to ordinary skill knowledge and customary means, make various replacements and change, all should comprise within the scope of the invention.
Embodiment 1
The technical process of present embodiment producing liquefied natural gas by coal bed gas in mine coal as shown in Figure 1.
The coal field coal-seam gas is through deoxygenation, desulfurization, and decarburization and dry back are as unstripped gas, and its flow is 6000Nm 3/ h, composition (vol%) is: CH 435%, N 265%.Pressure 4.3MPa, 30 ℃ of temperature.
Enter the first interchanger E1 by pipeline 1, cooling back enters the 4th interchanger E4 heating tower bottoms by pipeline 2, enters the second interchanger E2 by pipeline 3 and further cools off, and goes out the second interchanger E2 and is depressured to 2.1MPa by pipeline 4 by throttling, temperature-141 ℃ enters low-temperature fractionating tower T by pipeline 5.Under the refinery distillation of low-temperature fractionating tower T, the tower still obtains the liquid methane of 99.5% purity, temperature-108 ℃; Cat head is useless nitrogen, and temperature-154 ℃ contains methane 2.3%.
Useless nitrogen enters the second interchanger E2 by pipeline 6, be warmed up to-128 ℃, enter decompressor EXP by pipeline 13, going out expander pressure is 0.6MPa, enter pipeline 14 and be depressured to 0.14MPa by throttling, to normal temperature, discharge cryogenic unit by pipeline 15, the second interchanger E2, pipeline 16, the first interchanger E1 re-heat by pipeline 17.
The liquid methane of tower still enters the 3rd interchanger E3 by pipeline 7, crosses and is as cold as-130 ℃, is throttled to 0.14MPa through pipeline 8, is entered the condenser C of low-temperature fractionating tower T cat head by pipeline 9.To normal temperature, by pipeline 12 output cryogenic units, tolerance is 2017Nm to the methane of gasification by pipeline 10, the 3rd interchanger E3, pipeline 11, the first interchanger E1 re-heat 3/ h sends to the refrigeration liquefying device and carries out refrigeration liquefying.
Need the methane 2017Nm of liquefaction 3/ h enters compressor COP by pipeline 21 (with pipeline 12), goes out compressor one-level compression and is 2000Nm from pipeline 42, tolerance 3The gas that returns that hangs down intermediate pressure (0.3MPa) of/h mixes, and enters the next stage compression, is 1652Nm through three grades of compression outlets and from pipeline 36, tolerance 3The gas of the higher intermediate pressure (2.4MPa) of/h mixes, and enters the next stage compression, is pressurized to 15.0MPa at last, tolerance 5669Nm 3/ h.
Gas after the compression is through pipeline 22, the 7th interchanger E7, pipeline 23, the 6th interchanger (pre-cooler) E6, be pre-chilled to-45 ℃, further be cooled to-62 ℃ through pipeline 24, the 8th interchanger E8, go into pipeline 25, through being throttled to 2.5MPa, enter the first gas-liquid separator V1 by pipeline 26, separate obtaining not liquefied gas and liquid methane.
The not liquefied gas that is come out by the first gas-liquid separator V1 is through pipeline 27 separated into two parts, the tolerance 1125Nm of first part 3/ h goes into the 5th interchanger E5 through pipeline 29, the heating tower bottoms, and the liquefaction that itself is cooled enters pipeline 30, is throttled to about 0.4MPa, goes into second interchanger E2 cooling unstripped gas through pipeline 31, is converged by pipeline 32 and pipeline 41 and returns refrigeration system.Second section arrives normal temperature via pipeline 28, the 8th interchanger E8, pipeline 35, the 7th interchanger E7 re-heat, the gas that returns as higher intermediate pressure (2.4MPa) enters 4 sections on compressor by pipeline 36, mix with the gas after three grades of compressions of compressor, enter the level Four compression.
By the liquid methane that the first gas-liquid separator V1 comes out, it is cold excessively to enter the 9th interchanger E9 through pipeline 37, goes into pipeline 38, is throttled to 0.4MPa, goes into the second gas-liquid separator V2 by pipeline 39, separates obtain gasifying methane and liquefied methane.
Directly export tolerance 2017Nm by pipeline 40 by the liquefied methane that the second gas-liquid separator V2 comes out as product LNG 3/ h, the about 0.4Mpa of pressure, methane content are 99.5%.
The gasification methane that comes out by the second gas-liquid separator V2 by the methane blended of pipeline 41 and pipeline 32 after by pipeline 33, the 8th interchanger E8, pipeline 34, the 7th interchanger E7 re-heat to normal temperature, enter 2 sections on compressor by pipeline 42, mix with the gas after the compression of compressor one-level, enter the secondary compression.
The every liquefaction of this embodiment 1Nm 3Methane compression power consumption (contain the CMM material pressure and be reduced to 4.3MPa) is 0.977kWh/Nm 3
Embodiment 2
The technical process of present embodiment producing liquefied natural gas by coal bed gas in mine coal as shown in Figure 2.
The coal field coal-seam gas is through deoxygenation, desulfurization, and decarburization and dry back are as unstripped gas, and its flow is 6000Nm 3/ h, composition (vol%) is: CH 435%, N 265%.Pressure 4.3MPa, 30 ℃ of temperature.
Enter the first interchanger E1 by pipeline 1, the cooling back enters the 4th interchanger E4 by pipeline 2, the heating tower bottoms, enter the second interchanger E2 by pipeline 3 and further cool off, go out the second interchanger E2 and be depressured to 2.1MPa by throttling, temperature-141 ℃ by pipeline 4, enter low-temperature fractionating tower T by pipeline 5, under the refinery distillation of low-temperature fractionating tower T, the tower still obtains the liquid methane of 99.5% purity, temperature-108 ℃.Cat head is useless nitrogen, and temperature-154 ℃ contains methane 2.3%.
Useless nitrogen is by pipeline 6 and be throttled to 0.14MPa pressure and enter the second interchanger E2, to normal temperature, discharges cryogenic units by pipeline 14 by pipeline 13, the first interchanger E1 re-heat.
The liquid methane of tower still enters the 3rd interchanger E3 by pipeline 7, crosses and is as cold as-130 ℃, is throttled to 0.14MPa through pipeline 8, is entered the condenser C of low-temperature fractionating tower T cat head by pipeline 9.To normal temperature, by pipeline 12 output cryogenic units, tolerance is 2017Nm to the methane of gasification by pipeline 10, the 3rd interchanger E3, pipeline 11, the first interchanger E1 re-heat 3/ h sends to the refrigeration liquefying device and carries out refrigeration liquefying.
Need the methane 2017Nm of liquefaction 3/ h enters compressor COP by pipeline 21 (with pipeline 12), goes out compressor one-level compression and is 2060Nm from pipeline 44, tolerance 3The gas that returns that hangs down intermediate pressure (0.3MPa) of/h mixes, and enters the next stage compression, is 1807Nm three grades of compression outlets and from pipeline 36, tolerance 3The gas of the higher intermediate pressure (2.4MPa) of/h mixes, and enters the next stage compression, is pressurized to 15.0MPa at last, tolerance 5984Nm 3/ h.
Gas after the compression is through pipeline 22, the 7th interchanger E7, pipeline 23, the 6th interchanger (pre-cooler) E6, be pre-chilled to-45 ℃, further be cooled to-62 ℃ through pipeline 24, the 8th interchanger E8, go into pipeline 25, through being throttled to 2.5MPa, enter the first gas-liquid separator V1 by pipeline 26, separate obtaining not liquefied gas and liquid methane.
The not liquefied gas that is come out by the first gas-liquid separator V1 is through pipeline 27 separated into two parts, the tolerance 1125Nm of first part 3/ h goes into the 5th interchanger E5 through pipeline 29, the heating tower bottoms, and the liquefaction that itself is cooled is throttled to about 0.4MPa, goes into second interchanger E2 cooling unstripped gas through pipeline 31, is converged by pipeline 32 and pipeline 41 and returns the refrigeration liquefying device.Second section to normal temperature, enters compressor 4 section through pipeline 36 via pipeline 28, the 8th interchanger E8, pipeline 35, the 7th interchanger E7 re-heat, mixes with gas after three grades of compressions of compressor, enters level Four and compresses.
By the liquid methane that the first gas-liquid separator V1 comes out, cold excessively through the 9th interchanger E9, go into pipeline 38, be throttled to 0.4MPa, go into the second gas-liquid separator V2 by pipeline 39, separate obtain gasifying methane and liquefied methane.
Directly export tolerance 2017Nm by pipeline 40 by the liquefied methane that the second gas-liquid separator V2 comes out as product LNG 3/ h, the about 0.4Mpa of pressure, methane content are 99.5%.
The gasification methane that comes out by the second gas-liquid separator V2 by the methane blended of pipeline 41 and pipeline 32 after by pipeline 42, the 8th interchanger E8, pipeline 43, the 7th interchanger E7 re-heat to normal temperature, enter 2 sections on compressor by pipeline 42, mix with the gas after the compression of compressor one-level, enter the secondary compression.
Present embodiment low ternperature separation process part does not adopt useless nitrogen adiabatic expansion refrigeration, but provides cold by refrigeration system, can obtain the ideal refrigeration equally.
And, extract product natural gas liquids LNG 112Nm out by the second gas-liquid separator V2 in order to replenish the required cold of low temperature separation unit 3/ h (being converted into gaseous state) enters by pipeline 33 and changes the second hot device E2, the cooling unstripped gas, self gasified after pipeline 34 mixes with pipeline 32, the refrigeration cycle that enters lower pressure is returned the gas system, through reclaiming the cold re-heat to normal temperature, enter compressor secondary inlet by pipeline 44, mixes, enter secondary and compress with gas after the compression of compressor one-level.
The every liquefaction of this embodiment 1Nm 3Methane compression power consumption (contain the CMM material pressure and be reduced to 4.3MPa) is 1.01kWh/Nm 3
Embodiment 3
The technical process of present embodiment producing liquefied natural gas by coal bed gas in mine coal as shown in Figure 3.
The coal field coal-seam gas is through deoxygenation, desulfurization, and decarburization and dry back are as unstripped gas, and its flow is 6000Nm 3/ h, composition (vol%) is: CH 435%, N 265%.Pressure 4.3MPa, 30 ℃ of temperature.
Enter the first interchanger E1 by pipeline 1, the cooling back enters the 4th interchanger E4 by pipeline 2, the heating tower bottoms, enter the second interchanger E2 by pipeline 3 and further cool off, go out the second interchanger E2 and be depressured to 2.1MPa by throttling, temperature-141 ℃ by pipeline 4, enter low-temperature fractionating tower T by pipeline 5, under the refinery distillation of low-temperature fractionating tower T, the tower still obtains the liquid methane of 99.5% purity, temperature-108 ℃.Cat head is useless nitrogen, and temperature-154 ℃ contains methane 2.3%.
Useless nitrogen is by pipeline 6 and be throttled to 0.14MPa and enter the second interchanger E2, to normal temperature, discharges cryogenic units by pipeline 14 by pipeline 13, the first interchanger E1 re-heat.
The liquid methane of tower still enters the 3rd interchanger E3 by pipeline 7, crosses and is as cold as-130 ℃, is throttled to 0.14MPa through pipeline 8, enters condenser C by pipeline 9.To normal temperature, by pipeline 12 output cryogenic units, tolerance is 2017Nm to the methane of gasification by pipeline 10, the 3rd interchanger E3, pipeline 11, the first interchanger E1 re-heat 3/ h sends to the refrigeration liquefying device and carries out refrigeration liquefying.
Need the methane 2017Nm of liquefaction 3/ h enters compressor COP by pipeline 21 (with pipeline 12), goes out compressor one-level compression and is 7913Nm from pipeline 44, tolerance 3The gas that returns of/h mixes, and enters the next stage compression, is pressurized to 5.0Mpa through three grades of compressions.
Gas after the compression is through pipeline 22, the 7th interchanger E7, pipeline 23, the 6th interchanger (pre-cooler) E6, be pre-chilled to-45 ℃, entering the 8th interchanger E8 further cools off, be throttled to 3.0MPa again through pipeline 25, enter the first gas-liquid separator V1 through pipeline 26,, separate obtaining not liquefied gas and liquid methane.
By the not liquefied gas separated into two parts that the first gas-liquid separator V1 comes out, the tolerance 1125Nm of first part 3/ h through pipeline 29, the 5th interchanger E5, pipeline 30 heating tower bottomss, and liquefaction, is throttled to 0.4MPa, enters the second interchanger E2 by pipeline 31, and the cooling unstripped gas enters pipeline 42 by the methane blended of pipeline 32 and pipeline 41.Second section 5515Nm 3/ h is through through pipeline 28, the 8th interchanger E8 is warmed up to-48 ℃, enter decompressor EXP by pipeline 35, expand into 0.6MPa, be depressured to 0.4MPa again, merge through pipeline 36 and pipeline 42, enter the 8th interchanger E8 as returning gas, enter 2 sections of compressor COP through pipeline 43, the 7th interchanger E7, pipeline 44, mixes, enter secondary and compress with gas after the compressor one-level compression.
The V1 liquid methane that comes out by the first gas-liquid separator V1, cold excessively through pipeline 37, the 9th interchanger E9, be throttled to 0.4MPa again through pipeline 38, enter the second gas-liquid separator V2 through pipeline 39, separate obtain gasifying methane and liquefied methane.
Directly export tolerance 2017Nm by pipeline 40 by the liquefied methane that the second gas-liquid separator V2 comes out as product LNG 3/ h, the about 0.4Mpa of pressure, methane content are 99.5%.
The gasification methane that comes out by the second gas-liquid separator V2 by the methane blended of pipeline 41 and pipeline 32 after by pipeline 42, the 8th interchanger E8, pipeline 43, the 7th interchanger E7 re-heat to normal temperature, enter 2 sections on compressor by pipeline 44, mix with the gas after the compression of compressor one-level, enter the secondary compression.
Present embodiment has adopted rear-mounted methane adiabatic expansion refrigeration cycle.In order to replenish the required cold of low temperature separation unit, extract product natural gas liquids LNG 112Nm out by the second gas-liquid separator V2 3/ h (being converted into gaseous state) enters the second interchanger E2 by pipeline 33, the cooling unstripped gas, mix with the methane gas of pipeline 32 by pipeline 34 after self being gasified, the refrigeration cycle that enters lower pressure is returned the gas system, through reclaiming the cold re-heat to normal temperature, enter compressor secondary inlet by pipeline 44, mixes, enter secondary and compress with gas after the compression of compressor one-level.
The every liquefaction of this embodiment 1Nm 3Methane compression power consumption (contain the CMM material pressure and be reduced to 4.3MPa) is 1.12kWh/Nm 3

Claims (10)

1. the technology of a producing liquefied natural gas by coal bed gas in mine coal, the coal field coal-seam gas enters cryogenic unit as unstripped gas and carries out low ternperature separation process after deoxygenation, pressurization, desulfurization, decarburization and drying; After the cooling, the reboiler that enters rectifying tower is as the evaporation thermal source, and cooling in first interchanger, enters that second interchanger further cools off, throttling again, enters rectifying tower; Under the refinery distillation of rectifying tower, cat head obtains useless nitrogen, discharger after interchanger reclaims the cold re-heat; The tower still obtains liquid methane, and throttling is gone into overhead condenser as low-temperature receiver; The methane of evaporation is after interchanger reclaims the cold re-heat, as gases methane output cryogenic unit;
It is characterized in that:
In the low ternperature separation process operation, be provided for improving the auxiliary circulation of the steam output of rectifying tower reboiler, be throttled to a higher intermediate pressure by refrigeration system high pressure methane, extract a certain amount of not liquefied methane out and enter the rectifying tower reboiler as the evaporation thermal source, the methane liquefaction that is cooled, the low intermediate pressure of throttling to again, enter second interchanger and cool off into tower coal-seam gas, and then turn back to the corresponding position of refrigeration system; Cat head evaporates, the gases methane after re-heat is sent into refrigeration system again, carries out refrigeration liquefying and obtains liquid methane, promptly can be used as natural gas liquids output.
2. technology according to claim 1 is characterized in that:
Described higher intermediate pressure is for being higher than more than the rectifying tower pressure 0.2MPa;
Described low intermediate pressure is 0.3MPa～0.45MPa.
3. technology according to claim 1 is characterized in that:
The liquid methane that described rectifying Tata still obtains, with the methane of cat head evaporation cross cold after again throttling go into overhead condenser.
4. technology according to claim 1 is characterized in that:
In the described refrigeration liquefying operation, adopt the liquefaction cycle of the high pressure methane second throttle that has precooling, or have the rear methane expansion cycles of precooling, refrigeration agent is a methane.
5. technology according to claim 1 is characterized in that:
In the described cryogenic unit, provide the liquid methane of 0.3MPa～0.45MPa as low-temperature receiver by refrigeration system.
6. technology according to claim 1 is characterized in that:
Described low ternperature separation process operation comprises:
A, unstripped gas enter cryogenic unit, cool off by the first interchanger heat exchange;
B, enter the 4th interchanger in the rectifying tower reboiler,, in the heating tower bottoms, self be cooled as the evaporation thermal source of tower bottoms;
C, enter the further heat exchange of second interchanger cooling again;
D, through the throttling step-down, enter rectifying tower then, under the refinery distillation of rectifying tower, separate, cat head obtains useless nitrogen, the tower still obtains liquid methane;
The useless nitrogen that E, rectifying tower cat head obtain reclaims cold re-heat discharger to the normal temperature through second interchanger, first interchanger respectively;
The liquid methane that F, rectifying Tata still obtain, cold excessively through the 3rd interchanger, again after the throttling step-down, the condenser that enters the rectifying tower cat head is as low-temperature receiver; The methane gas of evaporation reclaims the cold re-heat to normal temperature through the 3rd interchanger, first interchanger respectively, as gases methane output cryogenic unit, enters refrigeration system and carries out next step refrigeration liquefying operation.
7. technology according to claim 6 is characterized in that:
In the described step e, the useless nitrogen that the rectifying tower cat head obtains after reclaiming cold through the second interchanger heat exchange, by the decompressor step-down of expanding, reclaims cold re-heat discharger to the normal temperature by the further heat exchange of first interchanger again.
8. according to claim 6 or 7 described technologies, it is characterized in that:
Described refrigeration liquefying operation comprises:
G, the gases methane of exporting from cryogenic unit enter the refrigeration liquefying device, carry out the compression of 3-5 level by compressor;
H, go out behind the compressor respectively through the 7th interchanger, the 6th interchanger, the 8th interchanger heat exchange cooling;
I, through the throttling step-down, enter first gas-liquid separator then and carry out the gas-liquid separation first time, obtain not liquefied gas and liquid methane respectively;
J, the not liquefied gas that first gas-liquid separator is obtained are divided into two portions;
J1, first part enter cryogenic unit, in the 5th interchanger in the rectifying tower reboiler of cryogenic unit, as the evaporation thermal source of tower bottoms, self are cooled and liquefy in the heating tower bottoms; Through the throttling step-down, again by second interchanger heat exchange gasification; Return refrigeration system then, with from step L after the gasification methane blended after the 9th interchanger re-heat, respectively by the 8th interchanger and the 7th interchanger heat exchange, re-heat to normal temperature, enter compressor again, mix with gases methane, enter the next stage compression jointly from cryogenic unit;
J2, second section respectively by the 8th interchanger and the 7th interchanger heat exchange, re-heat to normal temperature, enter compressor again, mixes with other gas in the compressor, enter next stage jointly and compress;
K, the liquid methane that is obtained by first gas-liquid separator are cold excessively through the 9th interchanger heat exchange; Again through the throttling step-down; Enter second gas-liquid separator then and carry out the gas-liquid separation second time, methane and liquid methane obtain respectively gasifying;
L, the gasification methane that obtains by second gas-liquid separator, through the 9th interchanger heat exchange, when crossing the liquid methane that cold first gas-liquid separator obtains, self is by re-heat; Mix by the cooled gas of the second interchanger heat exchange again with from step J1, pass through the 8th interchanger and the 7th interchanger heat exchange, re-heat then respectively, enter compressor again to normal temperature;
M, by the liquid methane that second gas-liquid separator obtains, export as natural gas liquids.
9. technology according to claim 8 is characterized in that:
In the described step K, after second gas-liquid separator carries out the gas-liquid separation second time, the liquid methane that obtains is extracted a part, after throttling, pass through the second interchanger heat exchange of cryogenic unit, further cooling self is heated from the unstripped gas of the 4th interchanger in the rectifying tower reboiler simultaneously; Return the refrigeration liquefying device then, with from step J1 by the cooled gas of the second interchanger heat exchange and from step L after the 9th interchanger re-heat the gasification methane blended, pass through the 8th interchanger and the 7th interchanger heat exchange, re-heat respectively to normal temperature, enter compressor again.
10. technology according to claim 8 is characterized in that:
Among the described step J2, second section in the not liquefied gas that obtains by first gas-liquid separator, after the 8th interchanger heat exchange, by the decompressor step-down of expanding, again with from step J1 by the cooled gas of the second interchanger heat exchange and from step L after the 9th interchanger re-heat the gasification methane blended, pass through the 8th interchanger and the 7th interchanger heat exchange, re-heat then respectively to normal temperature, enter compressor again.
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CN102654348A (en) * 2012-05-22 2012-09-05 中国海洋石油总公司 Method for producing liquefied natural gas by using coke oven gas
CN102654348B (en) * 2012-05-22 2015-01-28 中国海洋石油总公司 Method for producing liquefied natural gas by using coke oven gas
CN106536689A (en) * 2014-06-27 2017-03-22 Rtj技术有限责任公司 Method and arrangement for producing liquefied methane gas (LMG) from various gas sources
CN109916135A (en) * 2019-02-15 2019-06-21 酷豹低碳新能源装备科技(常州)有限公司 It is a kind of for small gas liquefying plant without pump circulation method
CN109916135B (en) * 2019-02-15 2021-09-24 酷豹低碳新能源装备科技(常州)有限公司 Pump-free circulation method for small gas liquefaction device
CN113881470A (en) * 2021-09-30 2022-01-04 深圳市英策科技有限公司 Device and method for obtaining liquid methane from mixture containing methane
CN113881470B (en) * 2021-09-30 2024-04-05 深圳市英策科技有限公司 Device and method for obtaining liquid methane from mixture containing methane

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