CN102538391B - Multi-level single-component refrigeration natural gas liquefaction system and multi-level single-component refrigeration natural gas liquefaction method - Google Patents
Multi-level single-component refrigeration natural gas liquefaction system and multi-level single-component refrigeration natural gas liquefaction method Download PDFInfo
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 328
- 239000003345 natural gas Substances 0.000 title claims abstract description 99
- 238000005057 refrigeration Methods 0.000 title claims abstract description 31
- 238000000034 method Methods 0.000 title abstract description 33
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims abstract description 212
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims abstract description 112
- 239000001294 propane Substances 0.000 claims abstract description 106
- 239000005977 Ethylene Substances 0.000 claims abstract description 48
- 239000003507 refrigerant Substances 0.000 claims abstract description 6
- 238000001704 evaporation Methods 0.000 claims description 19
- 230000008020 evaporation Effects 0.000 claims description 18
- 238000001816 cooling Methods 0.000 claims description 15
- 238000003860 storage Methods 0.000 claims description 13
- 238000003825 pressing Methods 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 7
- 125000000816 ethylene group Chemical class [H]C([H])([*:1])C([H])([H])[*:2] 0.000 claims description 3
- 238000005265 energy consumption Methods 0.000 abstract description 8
- 230000008901 benefit Effects 0.000 abstract description 4
- 238000010276 construction Methods 0.000 abstract description 4
- 239000002994 raw material Substances 0.000 abstract description 2
- 238000005516 engineering process Methods 0.000 description 11
- 239000007789 gas Substances 0.000 description 7
- 239000003949 liquefied natural gas Substances 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 238000002156 mixing Methods 0.000 description 5
- 235000019628 coolness Nutrition 0.000 description 2
- 210000004243 sweat Anatomy 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
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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
- 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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- 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
- F25J1/003—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
- F25J1/0047—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 an "external" refrigerant stream in a closed vapor compression cycle
- F25J1/0052—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 an "external" refrigerant stream in a closed vapor compression cycle by vaporising a liquid refrigerant stream
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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
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/006—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the refrigerant fluid used
- F25J1/008—Hydrocarbons
- F25J1/0082—Methane
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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
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/006—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the refrigerant fluid used
- F25J1/008—Hydrocarbons
- F25J1/0085—Ethane; Ethylene
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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
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/006—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the refrigerant fluid used
- F25J1/008—Hydrocarbons
- F25J1/0087—Propane; Propylene
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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
- 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
- F25J1/0203—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
- F25J1/0207—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 as at least a three level SCR refrigeration cascade
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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
- 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
- F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
- F25J1/0257—Construction and layout of liquefaction equipments, e.g. valves, machines
- F25J1/0262—Details of the cold heat exchange system
- F25J1/0263—Details of the cold heat exchange system using different types of heat exchangers
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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
- 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
- F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
- F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
- F25J1/0292—Refrigerant compression by cold or cryogenic suction of the refrigerant gas
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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
- F25J2250/00—Details related to the use of reboiler-condensers
- F25J2250/02—Bath type boiler-condenser using thermo-siphon effect, e.g. with natural or forced circulation or pool boiling, i.e. core-in-kettle heat exchanger
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- Mechanical Engineering (AREA)
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- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Separation By Low-Temperature Treatments (AREA)
Abstract
The invention discloses a multi-level single-component refrigeration natural gas liquefaction system and a multi-level single-component refrigeration natural gas liquefaction method. Purified natural gas is cooled gradually in six heat exchangers (evaporators) and a plate fin type heat exchanger (natural gas subcooler) until being liquefied. Cold energy required by the liquefying process is provided by a propane system, an ethylene system and a methane system. The system is rich in adjusting means, the cold energy matched with the natural gas liquefying process can be provided for the naturalgas liquefying process, and thereby operational flexibility and adaptability to raw materials of the method are embodied. The system and the method have the advantages that the natural gas liquefyingprocess is low in energy consumption; refrigerant compressors are all single-component compressors, so that design is easier, purchase is more convenient, the compressors are more stable in operation, domestic equipment can be used, and construction investment of liquefaction factories can be effectively reduced; and the liquefying process is wide in heat exchanger selection range, and a cold boxstructure and a tube-shell structure can be used simultaneously or alternatively.
Description
Technical field
The present invention relates to a kind of natural gas liquefaction process, especially relate to a kind of multistage one pack system refrigeration natural gas liquefaction system and method.
Background technology
Liquefied natural gas (LNG) has the performance of clean environment firendly, promotes rapidly in many applications such as middle samll cities and towns gas, industrial fuel, gas peak regulation and the accident emergency of no natural gas line arrival area, gas combustion automobile, high-grade porcelain processing.But be subjected to the influence of International Crude Oil, Gas Prices is constantly soaring, and natural gas liquefaction plant's benefit natural gas liquefaction plant cost of material constantly increases, thereby causes the liquefaction plant profit margin constantly to descend.Natural gas liquefaction plant develops to maximization, scale direction both at home and abroad in recent years, and the maximum liquefying power of single cover has arrived 7,800,000 tons/year at present.Energy consumption is low, construction cost is relatively low, can be applied to the developing direction that large-scale liquefaction process is China's liquefaction technology in future again.
Natural gas liquefaction process is broadly divided into following three kinds both at home and abroad at present:
1) stepwise kind of refrigeration cycle; 2) azeotrope kind of refrigeration cycle is subdivided into single-stage mixing cryogen circulation and the circulation of multistage azeotrope with or without precooling again; 3) swell refrigeration is subdivided into single-stage expansion refrigeration and multiple expansion refrigeration with or without precooling again.
Above technology is adapted to the natural gas liquefaction plant of different disposal scale because of characteristics separately.The natural gas liquefaction process of band swell refrigeration circulation is too high because of plant energy consumption, and single covering device treating capacity is little, is substituted by the mixing cryogen refrigerating cycle liquefied technology of single-stage gradually in recent years.Single-stage mixing cryogen refrigerating cycle liquefied technology is present domestic and international 50 * 10
4The main flow technology of the liquefaction factory of the following treatment scale of t/a.And mixing cryogen refrigerating cycle liquefied technology (C3/MRC) and the multistage azeotrope refrigeration liquefying flow path of the precooling of band propane are used for the above medium-and-large-sized base load type natural gas liquefaction device of natural gas more.The refrigerating cycle liquefied flow process energy consumption of stepwise is low, be applicable to 100 * 10
4The above ultra-large type natural gas liquefaction device of t/a.
As seen from the above analysis, mixing cryogen refrigerating cycle liquefied technology (C3/MRC), multistage azeotrope refrigeration liquefying flow path and the refrigerating cycle liquefied flow process of stepwise of the precooling of band propane can be applicable to large-scale or the ultra-large type natural gas liquefaction process.But be subjected to the monopolization of foreign natural gas liquefaction technology and key equipment, Chinese large-sized liquefaction factory construction cost can't be effectively controlled.Develop and a kind ofly can be applicable to that the large-scale natural gas liquefaction process of China's autonomy-oriented equipment that can use again is very necessary.
Summary of the invention
In order to overcome the above-mentioned shortcoming of prior art, the invention provides a kind of multistage one pack system refrigeration natural gas liquefaction system and method, combine traditional stepwise refrigeration process advantage, from the key equipment production domesticization technology of traditional stepwise refrigeration process has been carried out improving and innovation simultaneously, except having traditional stepwise refrigeration process characteristics, also have the characteristics of cryogen compressor, heat exchanger production domesticization, convenient buying, investment more economize.
The technical solution adopted for the present invention to solve the technical problems is: a kind of multistage one pack system refrigeration natural gas liquefaction system comprises that propane chilldown system, ethene liquefying refrigerating system and methane crosses cooling system; Described propane chilldown system comprises propane compressor, propane tank, high pressure propane evaporimeter, middle pressure propane evaporator and the low-pressure propane evaporimeter that connects successively; Described ethene liquefying refrigerating system comprises ethene storage tank, high-pressure ethylene evaporimeter, middle pressure ethene evaporimeter, low pressure ethylene evaporimeter and the ethylene compressor that connects successively; Described methane is crossed cooling system and is comprised natural gas subcooler and the methane compressor that connects successively; Described ethene storage tank is connected with the low-pressure propane evaporimeter, and described ethylene compressor is connected with the high pressure propane evaporimeter, and described methane compressor is connected with the high pressure propane evaporimeter.
The present invention also provides a kind of multistage one pack system refrigeration natural gas liquefaction, comprises the steps:
1) the propane chilldown system carries out precooling to natural gas, methane and ethylene refrigerant:
After natural gas, methane and ethene at first are cooled to-35 ℃ through three grades of propane device sweat coolings, enter the heat exchange cooling of ethene liquefying refrigerating system; The propane steam that comes out from three grades of propane evaporators through propane cooler water-cooled to 40 ℃, enters propane tank and stores after propane compressor is pressurized to 1.32MPa.g; Cold-producing medium propane from propane tank passes through the throttling of one-level J-T valve, and pressure enters the high pressure propane evaporimeter after being down to 0.735MPa.g, and natural gas, methane and ethene are cooled off; The gaseous propane of high pressure propane evaporator evaporation is got back to the propane compressor supercharging, and LPG is by the throttling of secondary J-T valve, and pressure enters the middle propane evaporator of pressing after being down to 0.305MPa.g, and natural gas, methane and ethene are cooled off; The middle gaseous propane of propane evaporator evaporation of pressing is got back to the propane compressor supercharging, LPG is by the throttling of three grades of J-T valves, pressure enters the low-pressure propane evaporimeter after being down to 0.011MPa.g, natural gas, methane and ethene are cooled off, and the gaseous propane of low-pressure propane evaporator evaporation is got back to the propane compressor supercharging and is circulated;
2) ethene liquefying refrigerating system is cooled to-95～-85 ℃ with natural gas, methane:
Ethene through ethylene chiller water-cooled to 40 ℃, enters the propane chilldown system and is cooled to-35 ℃ and liquefaction after ethylene compressor is pressurized to 1.9MPa.g, enters the ethene storage tank stores then; Through the throttling of one-level J-T valve, pressure enters the high-pressure ethylene evaporimeter after being down to 0.95MPa.g, and natural gas and methane are cooled off from-35 ℃ of liquid ethylenes of ethene storage tank; The ethene of high-pressure ethylene evaporator evaporation is got back to the ethylene compressor supercharging, and liquid ethylene is through the throttling of secondary J-T valve, and pressure enters the middle ethene evaporimeter of pressing after being down to 0.23MPa.g, and natural gas and methane are cooled off; The middle ethene of ethene evaporator evaporation of pressing is got back to the ethylene compressor supercharging, liquid ethylene is by the throttling of three grades of J-T valves, pressure enters the low pressure ethylene evaporimeter after being down to 0.017MPa.g, natural gas and methane are cooled off, and the ethene of low pressure ethylene evaporator evaporation is got back to the ethylene compressor supercharging and is circulated;
3) methane is crossed cooling system natural gas and the cold excessively cold that provides of methane self is provided:
Methane is crossed cooling system and the natural gas of ethene liquefying refrigerating system liquefaction is crossed by the natural gas subcooler is chilled to-150 ℃, cross the natural gas throttling after cold after temperature be down to-162 ℃, enter the LNG storage tank stores; Simultaneously, cold-producing medium methane is cooled in this one-level about-150 ℃, then by the choke valve decrease temperature and pressure, pressure is down to 100KPa, temperature enters the heat exchange of natural gas subcooler after being down to-152.9 ℃ again, temperature goes out the natural gas subcooler after being upgraded to-100 ℃～-120 ℃ again, and directly enter the methane compressor supercharging, after finishing, supercharging enters the circulation of propane chilldown system.
Compared with prior art, good effect of the present invention is: purified natural gas temperature in six heat exchangers (evaporimeter) and a plate-fin heat exchanger (natural gas subcooler) reduces gradually, until liquefaction; The required cold of liquefaction process is provided by propane, ethene, three systems of methane, and this system's regulating measure is abundant, can provide the cold that is complementary for gas deliquescence process, thereby embodies this method in operational flexibility with to the adaptability of raw material.Compared with prior art, have the following advantages:
One, the gas deliquescence process energy consumption is low.
For natural gas liquefaction, the principal element that influences energy consumption is the heat transfer temperature difference of cryogenic temperature and refrigeration heat transfer process.Under identical cryogenic temperature operating mode, heat transfer temperature difference is more big, and the energy consumption of refrigeration system is more high.
Adopt multistage one pack system of the present invention to carry out natural gas liquefaction, propane, ethene evaporate under 3 different evaporating pressures, are divided into 3 temperature grade cooled natural gas, and the vaporized refrigerant under each pressure enters corresponding compressor compresses.Adopt methane to provide cold as crossing cryogen for natural gas and the cooling of self at last.The whole heat transfer process temperature difference is comparatively even, no heat transfer bottleneck, and the available energy loss is little, and is energy-conservation obvious.Than the C3/MRC process energy consumption that generally uses at present low about 5%.
Two, the cryogen compressor is the one pack system compressor, and it is easier to design, and purchases more conveniently, and compressor operating is more stable, and can adopt production domesticization equipment, effectively reduces the construction investment of liquefaction factory.
The cryogen compressor comprises propane compressor, ethylene compressor, methane compressor, wherein the minimum suction temperature of propane compressor is-40～-35 ℃, the minimum suction temperature of ethylene compressor is-101 ℃, for propane compressor and ethylene compressor low temperature industry extensively utilization at home, so this compressor is easy to buying, the realization production domesticization.The minimum suction temperature of methane compressor in traditional stepwise refrigeration process is-150 ℃, and home equipment can't use, and has limited the popularization of this technology.
Adopt natural gas liquefaction process of the present invention, the minimum suction temperature of methane compressor is brought up to-120 ℃, adopts the one-level air inlet, and the compressor of this operating mode is existing ripe achievement in the low temperature industry at home, has solved the bottleneck of domestic Large LNG factory production domesticization.
Three, liquefaction process heat exchanger range of choice is big, can adopt the ice chest structure, also can adopt tube shell type structure, or both structure combining.
Both at home and abroad the main heat exchanger equipment of LNG factory mainly is around heat exchange of heat pipe and plate-fin heat exchanger, has only APCI and LINDE two families around the existing world production merchant of heat exchange of heat pipe, and price is higher, and plate-fin heat exchanger manufacturer at home is more.Main heat exchanger in the external Large LNG factory all adopt around pipe.Adopt natural gas liquefaction process of the present invention, main heat exchanger adopts tube shell type structure and plate-fin heat exchanger, and large-scale liquefaction plant production domesticization is limited by the form of main heat exchanger no longer.
Description of drawings
The present invention will illustrate by example and with reference to the mode of accompanying drawing, wherein:
Fig. 1 is system principle schematic diagram of the present invention.
The specific embodiment
A kind of multistage one pack system refrigeration natural gas liquefaction system, as shown in Figure 1, comprising: propane compressor 1, ethylene compressor 2, methane compressor 3, high pressure propane evaporimeter 4, middle pressure propane evaporator 5, low-pressure propane evaporimeter 6, high-pressure ethylene evaporimeter 7, middle pressure ethene evaporimeter 8, low pressure ethylene evaporimeter 9, natural gas subcooler 10, propane cooler 11, ethylene chiller 12, methane cooler 13, propane tank 14, ethene storage tank 15.Wherein:
Propane compressor 1, propane cooler 11, propane tank 14, high pressure propane evaporimeter 4, middle pressure propane evaporator 5 are connected successively with low-pressure propane evaporimeter 6, constitute the propane chilldown system, are used for natural gas, methane and ethylene refrigerant are carried out precooling.
Ethene storage tank 15, high-pressure ethylene evaporimeter 7, middle pressure ethene evaporimeter 8, low pressure ethylene evaporimeter 9, ethylene compressor 2 are connected successively with ethylene chiller 12, constitute ethene liquefying refrigerating system, are used for natural gas, methane are cooled to-95 ~-85 ℃.
A kind of multistage one pack system refrigeration natural gas liquefaction comprises the steps:
1) the propane chilldown system carries out precooling to natural gas, methane and ethylene refrigerant:
Natural gas, methane and ethene at first after high pressure propane evaporimeter 4, middle pressure propane evaporator 5 and 6 three grades of propane sweat coolings of low-pressure propane evaporimeter are cooled to-35 ℃, enter the heat exchange cooling of ethene liquefying refrigerating system.
The propane steam that comes out from three grades of propane evaporators through propane cooler 11 water-cooleds to 40 ℃, enters propane tank 14 and stores after propane compressor 1 is pressurized to 1.32MPa.g; Cold-producing medium propane from propane tank 14 passes through the throttling of one-level J-T valve, and pressure enters high pressure propane evaporimeter 4 after being down to 0.735MPa.g, and natural gas, methane and ethene are cooled off; The propane of high pressure propane evaporimeter 4 evaporations is got back to propane compressor 1 supercharging, and operative liquid propane is by the throttling of secondary J-T valve, and pressure enters the middle propane evaporator 5 of pressing after being down to 0.305MPa.g, and natural gas, methane and ethene are cooled off; The middle propane of propane evaporator 5 evaporations of pressing is got back to propane compressor 1 supercharging, operative liquid propane is by the throttling of three grades of J-T valves, pressure enters low-pressure propane evaporimeter 6 after being down to 0.011MPa.g, natural gas, methane and ethene are cooled off, and the propane of low-pressure propane evaporimeter 6 evaporations is got back to propane compressor 1 supercharging and is circulated.
2) ethene liquefying refrigerating system is cooled to-95～-85 ℃ with natural gas, methane:
Ethene through ethylene chiller 12 water-cooleds to 40 ℃, enters the propane chilldown system and is cooled to-35 ℃ and liquefaction after ethylene compressor 2 is pressurized to 1.9MPa.g, enters ethene storage tank 15 and stores; Through the throttling of one-level J-T valve, pressure enters high-pressure ethylene evaporimeter 7 after being down to 0.95MPa.g, and natural gas and methane are cooled off from-35 ℃ of liquid ethylenes of ethene storage tank 15; The ethene of high-pressure ethylene evaporimeter 7 evaporations is got back to ethylene compressor 2 superchargings, and operative liquid ethene is through the throttling of secondary J-T valve, and pressure enters the middle ethene evaporimeter 8 of pressing after being down to 0.23MPa.g, and natural gas and methane are cooled off; The middle ethene of ethene evaporimeter 8 evaporations of pressing is got back to ethylene compressor 2 superchargings, operative liquid ethene is by the throttling of three grades of J-T valves, pressure enters low pressure ethylene evaporimeter 9 after being down to 0.017MPa.g, natural gas and methane are cooled off, and the ethene of low pressure ethylene evaporimeter 9 evaporations is got back to ethylene compressor 2 superchargings and is circulated.
3) methane is crossed cooling system natural gas and the cold excessively cold that provides of methane self is provided:
Methane is as the cold-producing medium of super cooled sect, the natural gas that liquefaction stages (ethene liquefying refrigerating system) has been liquefied is by natural gas subcooler 10(plate-fin heat exchanger) cross and be chilled to-150 ℃, temperature is down to-162 ℃ after crossing the natural gas throttling after cold, enters the LNG storage tank stores; Simultaneously, cold-producing medium methane is cooled in this one-level about-150 ℃, and by the choke valve decrease temperature and pressure, pressure is down to 0.1MPa.g then, and temperature is down to-152.9 ℃, enters natural gas subcooler 10 again, and natural gas and self cold excessively cold that provides are provided.The temperature that methane after the throttling goes out natural gas subcooler 10 is-100 ℃～-120 ℃, and this gas directly enters methane compressor 3 superchargings, by methane cooler 13 water-cooleds, enters the circulation of propane chilldown system then after supercharging is finished.
The basic principle of multistage one pack system refrigeration natural gas liquefaction process is: the circulation of adjacent higher temperature level is given to heat in the circulation of lower temperature level.The circulation of first order propane refrigeration provides cold for natural gas, cold-producing medium ethene and cold-producing medium methane; Ethylene refrigeration circulation in the second level provides cold for natural gas and cold-producing medium methane; Third level methane refrigeration cycle is for natural gas and self provide cold.By six heat exchangers (evaporimeter 4 to 9) and a plate-fin heat exchanger (natural gas subcooler 10) cooling, the temperature of natural gas reduces gradually, until liquefaction.
Claims (2)
1. a multistage one pack system refrigeration natural gas liquefaction is characterized in that: comprise the steps:
1) the propane chilldown system carries out precooling to natural gas, methane and ethylene refrigerant:
After natural gas, methane and ethene at first are cooled to-35 ℃ through three grades of propane evaporators, enter the heat exchange cooling of ethene liquefying refrigerating system; The propane steam that comes out from three grades of propane evaporators through propane cooler water-cooled to 40 ℃, enters propane tank and stores after propane compressor is pressurized to 1.32MPa.g; Cold-producing medium propane from propane tank passes through the throttling of one-level J-T valve, and pressure enters the high pressure propane evaporimeter after being down to 0.735MPa.g, and natural gas, methane and ethene are cooled off; The gaseous propane of high pressure propane evaporator evaporation is got back to the propane compressor supercharging, and LPG is by the throttling of secondary J-T valve, and pressure enters the middle propane evaporator of pressing after being down to 0.305MPa.g, and natural gas, methane and ethene are cooled off; The middle gaseous propane of propane evaporator evaporation of pressing is got back to the propane compressor supercharging, LPG is by the throttling of three grades of J-T valves, pressure enters the low-pressure propane evaporimeter after being down to 0.011MPa.g, natural gas, methane and ethene are cooled off, and the gaseous propane of low-pressure propane evaporator evaporation is got back to the propane compressor supercharging and is circulated;
2) ethene liquefying refrigerating system is cooled to-95～-85 ℃ with natural gas, methane:
Ethene through ethylene chiller water-cooled to 40 ℃, enters the propane chilldown system and is cooled to-35 ℃ and liquefaction after ethylene compressor is pressurized to 1.9MPa.g, enters the ethene storage tank stores then; Through the throttling of one-level J-T valve, pressure enters the high-pressure ethylene evaporimeter after being down to 0.95MPa.g, and natural gas and methane are cooled off from-35 ℃ of liquid ethylenes of ethene storage tank; The ethene of high-pressure ethylene evaporator evaporation is got back to the ethylene compressor supercharging, and liquid ethylene is through the throttling of secondary J-T valve, and pressure enters the middle ethene evaporimeter of pressing after being down to 0.23MPa.g, and natural gas and methane are cooled off; The middle ethene of ethene evaporator evaporation of pressing is got back to the ethylene compressor supercharging, liquid ethylene is by the throttling of three grades of J-T valves, pressure enters the low pressure ethylene evaporimeter after being down to 0.017MPa.g, natural gas and methane are cooled off, and the ethene of low pressure ethylene evaporator evaporation is got back to the ethylene compressor supercharging and is circulated;
3) methane is crossed cooling system natural gas and the cold excessively cold that provides of methane self is provided:
Methane is crossed cooling system and the natural gas of ethene liquefying refrigerating system liquefaction is crossed by the natural gas subcooler is chilled to-150 ℃, cross the natural gas throttling after cold after temperature be down to-162 ℃, enter the LNG storage tank stores; Simultaneously, cold-producing medium methane is cooled in this one-level about-150 ℃, then by the choke valve decrease temperature and pressure, pressure is down to 0.1MPa.g, temperature enters the heat exchange of natural gas subcooler after being down to-152.9 ℃ again, temperature goes out the natural gas subcooler after being upgraded to-100 ℃～-120 ℃ again, and directly enter the methane compressor supercharging, after finishing, supercharging enters the circulation of propane chilldown system.
2. multistage one pack system refrigeration natural gas liquefaction according to claim 1, it is characterized in that: described natural gas subcooler is plate-fin heat exchanger.
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| EP3781885A1 (en) * | 2018-04-20 | 2021-02-24 | Chart Energy & Chemicals, Inc. | Mixed refrigerant liquefaction system and method with pre-cooling |
| CN108613478A (en) * | 2018-05-15 | 2018-10-02 | 中国石油工程建设有限公司 | A kind of extremely cold area natural gas liquefaction device and method |
| CN110186251B (en) * | 2019-06-11 | 2024-01-26 | 中国石油集团工程股份有限公司 | Three-cycle natural gas liquefaction device and method suitable for ultra-large scale |
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