CN105444523B - Using BOG itself compression-expansions liquefaction BOG re-liquefied system and technique - Google Patents

Using BOG itself compression-expansions liquefaction BOG re-liquefied system and technique Download PDF

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Publication number
CN105444523B
CN105444523B CN201510694345.6A CN201510694345A CN105444523B CN 105444523 B CN105444523 B CN 105444523B CN 201510694345 A CN201510694345 A CN 201510694345A CN 105444523 B CN105444523 B CN 105444523B
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bog
heat exchanger
cooler
turbo
expander
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CN105444523A (en
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缪越
张行东
王丹
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China Air Separation Engineering Co Ltd
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China Air Separation Engineering Co Ltd
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/0002Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
    • F25J1/0022Hydrocarbons, e.g. natural gas
    • F25J1/0025Boil-off gases "BOG" from storages
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003Processes 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
    • F25J1/0032Processes 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"
    • F25J1/0035Processes 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
    • F25J1/0037Processes 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
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02Processes 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
    • F25J1/0201Processes 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 only internal refrigeration means, i.e. without external refrigeration
    • F25J1/0202Processes 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 only internal refrigeration means, i.e. without external refrigeration in a quasi-closed internal refrigeration loop
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02Processes 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
    • F25J1/0243Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0279Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
    • F25J1/0285Combination of different types of drivers mechanically coupled to the same refrigerant compressor, possibly split on multiple compressor casings
    • F25J1/0288Combination of different types of drivers mechanically coupled to the same refrigerant compressor, possibly split on multiple compressor casings using work extraction by mechanical coupling of compression and expansion of the refrigerant, so-called companders
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2220/00Processes or apparatus involving steps for the removal of impurities
    • F25J2220/60Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
    • F25J2220/62Separating low boiling components, e.g. He, H2, N2, Air

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

The present invention relates to a kind of re-liquefied system and technique using BOG itself compression-expansions liquefaction BOG, reduce equipment, reduce cost, and energy consumption is low, start and stop fast response time, operating flexibility is big, and varying duty ability is strong, applied widely.The BOG that LNG storage tank evaporates first converges after heat exchanger reclaims cold into BOG surge tanks with the BOG as cryogen, and then into BOG compressors, the BOG after compression is divided into two parts after the first cooler;Part I BOG, which enters in heat exchanger, to be further cooled by entering gas-liquid separator progress gas-liquid separation through choke valve after liquefaction;Part II is used as the cryogen of Part I, the BOG of the part enters heat exchanger after the second cooler water cooling after turbo-expander is pressurized and cooled down, enter back into turbo-expander expansion, BOG after expansion returns to heat exchanger and provides cold while converged after re-heat into the BOG of BOG surge tanks and Part I, so circulation.

Description

Using BOG itself compression-expansions liquefaction BOG re-liquefied system and technique
Technical field
The present invention relates to a kind of re-liquefied system and technique using BOG itself compression-expansions liquefaction BOG.
Background technology
Natural gas is as a kind of high-quality, clean energy, and its calorific value is high, and environmental pollution is small, it is considered to be following preferred The energy.Normal pressure liquefied natural gas(LNG)As a kind of existence form of natural gas, its volume just corresponds to mark the 1/ of condition volume 625, it is advantageous to transport and stores.It is growing day by day to Natural Gas Demand with the world and China's expanding economy, LNG with Its very high economy, flexibility etc. are favored by countries in the world.Due to the special conditions of storage of LNG, LNG liquefaction works Substantial amounts of BOG gases are produced in factory, LNG transfer stations and LNG receiving stations, main source is natural evaporation and LNG grooves in LNG storage tank Substantial amounts of BOG gases are produced when car fills.BOG is to return to reliquefaction disposal in unstripped gas mostly in liquefaction plant at present, but is worked as When liquefaction plant stops production, the BOG evaporated can not be handled, and if being configured without reliquefaction disposal dress in receiving station and transfer station Put, these BOG can only be vented burning, while being polluted to environment, waste the substantial amounts of energy, cause energy consumption height etc. to ask Topic.
The quality of the re-liquefied techniques of BOG will directly affect the safety and economic benefit of LNG accumulatings.Current use The re-liquefied techniques of BOG substantially have two kinds:One kind compresses swell refrigeration technique for nitrogen, and the technique is employed nitrogen as refrigerant, Compression-expansion provides refrigerating capacity for BOG;The technique needs independent nitrogen kind of refrigeration cycle, and flow sheet equipment is more and complicated, energy consumption phase To higher.Second is to use BOG direct condensations, weight after BOG is mixed after BOG compressor compresses with the LNG from pump New condensation, utilizes the LNG exported from LNG storage tank cold energy;This process energy consumption is low, but when being only applicable to continuous LNG output Situation.
The Chinese patent of Application No. 201510167535.2 discloses a kind of re-liquefied techniques of BOG and its re-liquefied recovery System, itself is made using cold caused by BOG itself compression deutomerite streams during being cooled down to BOG It is cold so that BOG is re-liquefied, is collected into again in LNG storage tanks, so as to avoid using other refrigerant liquefactions BOG The cost increase brought.But the technological process of the technical scheme and system unit volume BOG energy consumption are very high(In patent Point out as 3.45~7.655KW.h/Nm3), still have significant optimization space.
The content of the invention
It is an object of the invention to overcome above shortcomings in the prior art, and provide a kind of use rational in infrastructure BOG itself compression-expansions liquefaction BOG re-liquefied system and technique, by using BOG itself as refrigerant, it is only necessary to which 1 often Warm BOG compressors, 1 turbo-expander and 1 heat exchanger, significantly simplify flow, reduce equipment, reduce cost, And energy consumption is low, start and stop fast response time, operating flexibility is big, and varying duty ability is strong, applied widely.
Technical scheme is used by the present invention solves the above problems:It is a kind of to liquefy BOG's using BOG itself compression-expansions Re-liquefied system, it is characterised in that:LNG storage tank, BOG surge tanks, BOG compressors, turbo-expander, heat exchanger, choke valve, gas Liquid/gas separator, the first cooler and the second cooler;
Heat exchanger has first flow, second flow channel, third flow channel and the 4th runner;
The BOG outlets of LNG storage tank connect with the cold-side inlet of the first flow of heat exchanger, and the first flow of heat exchanger Hot junction outlet connects with the entrance of BOG surge tanks;The outlet of BOG surge tanks connects with the entrance of BOG compressors;BOG compressors Outlet connected with the entrance of the first cooler;
The outlet of first cooler connects with the hot-side inlet of the second flow channel of heat exchanger, and the second flow channel of heat exchanger Cold side outlet connects with the entrance of choke valve, and the outlet of choke valve connects with the entrance of gas-liquid separator, and gas-liquid separator goes out Mouth connects with the entrance of LNG storage tank;
The outlet of first cooler also connects with the supercharging end entrance of turbo-expander, the pressurized end outlet of turbo-expander Connected with the entrance of the second cooler, the outlet of the second cooler connects with the hot-side inlet of the third flow channel of heat exchanger, and changes The cold side outlet of the third flow channel of hot device connects with the expansion end entrance of turbo-expander;Turbo-expander expanding end outlet with The cold-side inlet connection of 4th runner of heat exchanger, and the outlet of the hot junction of the 4th runner of heat exchanger and the entrance of BOG surge tanks Connection.
Present invention additionally comprises threeway;The outlet of first cooler and three general pipeline communications, two outlet difference of threeway Connected with the hot-side inlet of the second flow channel of heat exchanger and the supercharging end entrance of turbo-expander.
First cooler and the second cooler of the present invention are water cooler.
A kind of re-liquefied technique for the BOG that liquefied using BOG itself compression-expansions, it is characterised in that:Using above-mentioned system Handled;
The BOG that LNG storage tank evaporates first through heat exchanger reclaim cold re-heat to 15~30 DEG C, enter back into BOG surge tanks with The BOG as cryogen of same re-heat to 15~30 DEG C converges, then into BOG compressor compresses to 600~1000Kpa.A, BOG after compression is divided into two parts after the first cooler is cooled to 35~40 DEG C;
Part I BOG, which enters in heat exchanger, is further cooled by liquefaction to -150~-155 DEG C, afterwards through choke valve section Enter gas-liquid separator to 120Kpa.A after stream and carry out gas-liquid separation, the high gas emptying of the nitrogen content isolated, liquid enters LNG storage tank stores;
Part II is used as the cryogen of Part I, and the pressurized end that the BOG of the part first passes through turbo-expander is pressurized to 1000~1200Kpa.A, then it is cooled to -95~-110 DEG C into heat exchanger to after 35~40 DEG C through the second cooler water cooling, then Into turbo-expander expanding end be expanded to 130~150Kpa.A, -155~-160 DEG C, BOG after expansion returns to heat exchanger There is provided cold simultaneously by re-heat to the BOG for entering BOG surge tanks and Part I after 15~30 DEG C to be converged, so circulation.
The re-liquefied technique of the BOG of the present invention that liquefied using BOG itself compression-expansions, it is characterised in that:
The BOG that LNG storage tank evaporates first reclaims cold re-heat to 20 DEG C through heat exchanger, enter back into BOG surge tanks with it is same The BOG as cryogen of re-heat to 20 DEG C converges, and then into BOG compressor compresses to 700Kpa, the BOG after compression is through first Cooler is divided into two parts after being cooled to 40 DEG C;
Part I BOG, which enters in heat exchanger, is further cooled by liquefaction to -152 DEG C, afterwards after choke valve throttles extremely 120Kpa enters gas-liquid separator and carries out gas-liquid separation, and the high gas emptying of the nitrogen content isolated, liquid stores up into LNG storage tank Deposit;
Part II is used as the cryogen of Part I, and the pressurized end that the BOG of the part first passes through turbo-expander is pressurized to 1080Kpa, then enter back into the swollen of turbo-expander to being cooled to -100 DEG C into heat exchanger after 40 DEG C through the second cooler water cooling Swollen end is expanded to 130Kpa and -160 DEG C, and BOG after expansion returns to heat exchanger and provides cold simultaneously by re-heat to entering after 20 DEG C The BOG of BOG surge tanks and Part I converges, so circulation.
The present invention compared with prior art, has advantages below and effect:
1st, refrigerant of the invention uses BOG in itself, without extra cryogen and cryogen preparation facilities, reduces refrigeration and follows The configuration of cryogen storage tank in ring, reduces extra refrigerant compressor, it is only necessary to the BOG compressors of 1 normal temperature, makes whole flow process more Add simply, investment more saves.
2nd, the pressure after BOG compressor compresses of the invention is 700Kpa, can use helical-lobe compressor, reliability is high, the longevity Life is long, automaticity is high, strong adaptability, reduced investment;And in LNG liquefaction plants, also compressed using original BOG Machine, without extra configuration.
3rd, flow of the present invention is simple, and equipment is few, only 1 normal temperature BOG compressor, 1 BOG turbo-expander, 1 heat exchange Device, 1 choke valve and flash tank, reduced investment and can realize skid at good economy performance.
4th, gas is vented after throttling, and is avoided the aggregation of nitrogen content in whole technique stream and is increased energy consumption.
5th, two parts are divided after present invention compression, for a part to need liquefied BOG amounts, a part is into turbo-expander Refrigerant amount, the refrigerant amount or tune of turbo-expander according to the situation of BOG amounts and component in actual items, can be adjusted into Pressure meets the requirement of refrigerating capacity after whole turbo-expander machine, the requirement that is allowed to meet disparity items difference BOG amounts and becomes negative Lotus produces, and operation is easy to adjust simple, and adaptability is good.
6th, this flow uses turbine expander refrigeration, the characteristics of making full use of expanding machine high pressure, high enthalpy drop, reduces energy Consumption;The output work of expanding machine is made full use of, cryogen BOG is expanded after continuing supercharging, improves refrigerating capacity;
7th, the BOG that storage tank evaporates avoids the waste of cold, reduces energy by entering compressor after heat exchanger re-heat Consumption, and compressor can use normal temperature compressed machine, greatly reduce cost.
Therefore, the present invention has that flow is simple, floor space is small, reduced investment, and plant energy consumption is low, and operating flexibility is big, Varying duty ability is strong, applied widely, and the advantages that being easy to do sled block, being particularly suitable for use in LNG receiving stations or has a unnecessary BOG LNG Liquefaction plant.
Brief description of the drawings
Fig. 1 is the structural representation of system of the embodiment of the present invention.
Embodiment
Below in conjunction with the accompanying drawings and the present invention is described in further detail by embodiment, and following examples are to this hair Bright explanation and the invention is not limited in following examples.
Referring to Fig. 1, the embodiment of the present invention includes LNG storage tank using BOG itself compression-expansions liquefaction BOG re-liquefied system 1st, BOG surge tanks 2, BOG compressors 3, turbo-expander 4, heat exchanger 5, choke valve 6, gas-liquid separator 7, the and of the first cooler 8 Second cooler 9.
Heat exchanger 5 has first flow, second flow channel, third flow channel and the 4th runner.
First cooler and the second cooler are water cooler.
The BOG outlets of LNG storage tank 1 and the cold-side inlet pipeline communication of the first flow of heat exchanger 5, and heat exchanger 5 The hot junction outlet of first flow and the entrance pipeline communication of BOG surge tanks 2;The outlet of BOG surge tanks 2 and BOG compressors 3 Entrance pipeline communication;The outlet of BOG compressors 3 and the entrance pipeline communication of the first cooler 8.
The outlet of first cooler 8 and the hot-side inlet pipeline communication of the second flow channel of heat exchanger 5, and heat exchanger 5 The cold side outlet of second flow channel and the entrance pipeline communication of choke valve 6, the outlet of choke valve 6 and the entrance of gas-liquid separator 7 With pipeline communication, the outlet of gas-liquid separator 7 and the entrance pipeline communication of LNG storage tank 1.
Supercharging end entrance pipeline communication of the outlet of first cooler 8 also with turbo-expander 4, turbo-expander 4 Pressurized end exports the entrance pipeline communication with the second cooler 9, the outlet of the second cooler 9 and the third flow channel of heat exchanger 5 Hot-side inlet pipeline communication, and the expansion end entrance of the cold side outlet of the third flow channel of heat exchanger 5 and turbo-expander 4 is used Pipeline communication;The expanding end outlet of turbo-expander 4 and the cold-side inlet pipeline communication of the 4th runner of heat exchanger 5, and change The hot junction outlet of 4th runner of hot device 5 and the entrance pipeline communication of BOG surge tanks 2.
The outlet of first cooler 8 and three general pipeline communications, and two of threeway outlets respectively with heat exchanger 5 second The hot-side inlet of runner and the supercharging end entrance pipeline communication of turbo-expander 4, the outlet of such first cooler 8 are just distinguished With the hot-side inlet of the second flow channel of heat exchanger 5 and the supercharging end entrance pipeline communication of turbo-expander 4.
The present invention is as follows using BOG itself compression-expansions liquefaction BOG re-liquefied technique:
The BOG pressure that LNG storage tank 1 evaporates is 120Kpa.A, temperature is -140~-160 DEG C, and the BOG is first through heat exchanger 5 Cold re-heat is reclaimed to 15~30 DEG C, BOG surge tanks 2 is entered back into and the cryogen BOG of same re-heat to 15~30 DEG C converges, then 600~1000Kpa.A is compressed into BOG compressors 3, the BOG after compression divides after the first cooler 8 is cooled to 35~40 DEG C For two parts.
Part I BOG flow is the BOG amounts that LNG storage tank 1 evaporates, and pressure is 600~1000Kpa.A, temperature For 35~40 DEG C, this part is the BOG amounts that BOG flashes off from LNG storage tank 1 per hour, and this part BOG enters heat exchanger 5 In be further cooled by liquefaction to -150~-155 DEG C, enter afterwards after the throttling of choke valve 6 to 120Kpa into gas-liquid separator 7 Row gas-liquid separation, the high gas emptying of the nitrogen content isolated, liquid store into LNG storage tank 1.
Part II is used as the cryogen of Part I, and its flow of the BOG of the part is 6~9 times of Part I BOG amounts, Pressure is 600~1000Kpa.A, temperature is 35~40 DEG C, and the pressurized end that this part BOG first passes through turbo-expander 4 is pressurized to 1000~1200Kpa.A, then through the water cooling of the second cooler 9 to being cooled to -95~-110 DEG C into heat exchanger 5 after 35~40 DEG C, Enter back into turbo-expander 4 expanding end be expanded to 130~150Kpa.A, -155~-160 DEG C, BOG after expansion returns to heat exchange Device 5 provides cold and converged simultaneously by re-heat to the BOG for entering BOG surge tanks 2 and Part I after 15~30 DEG C, so circulates.
Refrigerant needed for above-mentioned expansion flow, after BOG compressors, during driving, first with after BOG compressors Gas introduces the pressurized end of turbo-expander 4, after expanding required refrigerant amount and reaching refrigeration requirement, regulation BOG compressors 3 Remove the valve of the supercharging contracting of turbo-expander 4., can be by adjusting refrigerant BOG after normal temperature BOG compressors when BOG amounts change Amount and heat exchanger after cryogen BOG temperature and turbo-expander after pressure meet the requirement of refrigerating capacity.
The embodiment of the present invention is as follows using BOG itself compression-expansions liquefaction BOG re-liquefied process optimization scheme:
Its flow of the BOG that LNG storage tank 1 evaporates is 800Nm3/ h, pressure 120Kpa.A, temperature are -140 DEG C, the BOG Cold re-heat first is reclaimed to 20 DEG C through heat exchanger 5, enters back into BOG surge tanks 2 and the cryogen BOG of same re-heat to 20 DEG C converges, 700Kpa then is compressed into BOG compressors 3, the BOG after compression is divided into two after the first cooler 8 is cooled to 40 DEG C Point.
Part I BOG flow is 800Nm3/ h, pressure 700Kpa.A, temperature are 40 DEG C, and this part is BOG per small When the BOG amounts that are flashed off from LNG storage tank 1, this part BOG, which enters in heat exchanger 5, is further cooled by liquefaction to -152 DEG C, Enter gas-liquid separator 7 to 120Kpa after the throttling of choke valve 6 afterwards and carry out gas-liquid separation, the high gas of the nitrogen content isolated Emptying, liquid store into LNG storage tank 1.
Part II is used as the cryogen of Part I, and its flow of the BOG of the part is 5800 Nm3/ h, pressure are 700Kpa.A, temperature are 40 DEG C, and the pressurized end that this part BOG first passes through turbo-expander 4 is pressurized to 1080Kpa, then through second To being cooled to -100 DEG C into heat exchanger 5 after 40 DEG C, the expanding end for entering back into turbo-expander 4 is expanded to the water cooling of cooler 9 130Kpa, -160 DEG C, BOG after expansion returns to heat exchanger 5 and provides cold simultaneously by re-heat to entering BOG surge tanks 2 after 20 DEG C Converge with the BOG of Part I, so circulation.
Refrigerant needed for above-mentioned expansion flow, after BOG compressors, during driving, first with after BOG compressors Gas introduces the pressurized end of turbo-expander 4, after expanding required refrigerant amount and reaching refrigeration requirement, regulation BOG compressors 3 Remove the valve of the supercharging contracting of turbo-expander 4., can be by adjusting refrigerant BOG after normal temperature BOG compressors when BOG amounts change Amount and heat exchanger after cryogen BOG temperature and turbo-expander after pressure meet the requirement of refrigerating capacity.
Furthermore, it is necessary to illustrate, the specific embodiment described in this specification, the shape of its parts and components, it is named Title etc. can be different, and the above content described in this specification is only to structure example explanation of the present invention.

Claims (5)

  1. A kind of 1. re-liquefied system for the BOG that liquefied using BOG itself compression-expansions, it is characterised in that:LNG storage tank, BOG bufferings Tank, BOG compressors, turbo-expander, heat exchanger, choke valve, gas-liquid separator, the first cooler and the second cooler;
    Heat exchanger has first flow, second flow channel, third flow channel and the 4th runner;
    The BOG outlets of LNG storage tank connect with the cold-side inlet of the first flow of heat exchanger, and the hot junction of the first flow of heat exchanger Outlet connects with the entrance of BOG surge tanks;The outlet of BOG surge tanks connects with the entrance of BOG compressors;BOG compressors go out Mouth connects with the entrance of the first cooler;
    The outlet of first cooler connects with the hot-side inlet of the second flow channel of heat exchanger, and the cold end of the second flow channel of heat exchanger Outlet connected with the entrance of choke valve, the outlet of choke valve connects with the entrance of gas-liquid separator, the outlet of gas-liquid separator and The entrance connection of LNG storage tank;
    The outlet of first cooler also connects with the supercharging end entrance of turbo-expander, the pressurized end of turbo-expander outlet and the The entrance connection of two coolers, the outlet of the second cooler connects with the hot-side inlet of the third flow channel of heat exchanger, and heat exchanger The cold side outlet of third flow channel connected with the expansion end entrance of turbo-expander;The expanding end outlet and heat exchange of turbo-expander The cold-side inlet connection of 4th runner of device, and the outlet of the hot junction of the 4th runner of heat exchanger connects with the entrance of BOG surge tanks.
  2. 2. the re-liquefied system of the BOG according to claim 1 that liquefied using BOG itself compression-expansions, it is characterised in that: Also include threeway;The outlet of first cooler and three general pipeline communications, two outlets of threeway respectively with heat exchanger second The hot-side inlet of runner connects with the supercharging end entrance of turbo-expander.
  3. 3. the re-liquefied system of the BOG according to claim 1 or 2 that liquefied using BOG itself compression-expansions, its feature are existed In:The first described cooler and the second cooler are water cooler.
  4. A kind of 4. re-liquefied technique for the BOG that liquefied using BOG itself compression-expansions, it is characterised in that:Using claims 1 to 3 System described in any claim is handled;
    The BOG that LNG storage tank evaporates first reclaims cold re-heat to 15~30 DEG C through heat exchanger, enter back into BOG surge tanks with it is same The BOG as cryogen of re-heat to 15~30 DEG C converges, and then into BOG compressor compresses to 600~1000Kpa.A, compresses BOG afterwards is divided into two parts after the first cooler is cooled to 35~40 DEG C;
    Part I BOG, which enters in heat exchanger, is further cooled by liquefaction to -150~-155 DEG C, afterwards after choke valve throttles Enter gas-liquid separator to 120Kpa.A and carry out gas-liquid separation, the high gas emptying of the nitrogen content isolated, liquid stores up into LNG Tank stores;
    Part II is used as the cryogen of Part I, and the pressurized end that the BOG of the part first passes through turbo-expander is pressurized to 1000 ~1200Kpa.A, then entered back into through the second cooler water cooling to being cooled to -95~-110 DEG C into heat exchanger after 35~40 DEG C The expanding end of turbo-expander be expanded to 130~150Kpa.A, -155~-160 DEG C, BOG after expansion returns to heat exchanger and provided Cold is converged by re-heat to the BOG for entering BOG surge tanks and Part I after 15~30 DEG C simultaneously, so circulation.
  5. 5. the re-liquefied technique of the BOG according to claim 4 that liquefied using BOG itself compression-expansions, it is characterised in that:
    The BOG that LNG storage tank evaporates first reclaims cold re-heat to 20 DEG C through heat exchanger, enters back into BOG surge tanks and same re-heat Converge to 20 DEG C of the BOG as cryogen, then into BOG compressor compresses to 700Kpa, the BOG after compression is through the first cooling Device is divided into two parts after being cooled to 40 DEG C;
    Part I BOG, which enters in heat exchanger, is further cooled by liquefaction to -152 DEG C, afterwards after choke valve throttles extremely 120Kpa enters gas-liquid separator and carries out gas-liquid separation, and the high gas emptying of the nitrogen content isolated, liquid stores up into LNG storage tank Deposit;
    Part II is used as the cryogen of Part I, and the pressurized end that the BOG of the part first passes through turbo-expander is pressurized to 1080Kpa, then enter back into the swollen of turbo-expander to being cooled to -100 DEG C into heat exchanger after 40 DEG C through the second cooler water cooling Swollen end is expanded to 130Kpa and -160 DEG C, and BOG after expansion returns to heat exchanger and provides cold simultaneously by re-heat to entering after 20 DEG C The BOG of BOG surge tanks and Part I converges, so circulation.
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CN108870866A (en) * 2017-05-09 2018-11-23 中海石油气电集团有限责任公司 It is a kind of to make the re-liquefied recovery process of BOG that refrigerant is suitable for LNG cargo ship using BOG
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WO2019231001A1 (en) * 2018-05-29 2019-12-05 주식회사 엔케이 Bog reliquefaction system and bog reliquefaction method using same
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CN114017989A (en) * 2021-12-01 2022-02-08 上海齐耀动力技术有限公司 LNG-BOG reliquefaction system and mixed refrigerant suitable for same
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