CN105444523A - Reliquefaction system and technique for compressing expanded liquified BOG through BOG - Google Patents
Reliquefaction system and technique for compressing expanded liquified BOG through BOG Download PDFInfo
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- CN105444523A CN105444523A CN201510694345.6A CN201510694345A CN105444523A CN 105444523 A CN105444523 A CN 105444523A CN 201510694345 A CN201510694345 A CN 201510694345A CN 105444523 A CN105444523 A CN 105444523A
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- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000003860 storage Methods 0.000 claims abstract description 31
- 239000007788 liquid Substances 0.000 claims abstract description 29
- 238000000926 separation method Methods 0.000 claims abstract description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 20
- 238000004891 communication Methods 0.000 claims description 19
- 239000007789 gas Substances 0.000 claims description 12
- 229910052757 nitrogen Inorganic materials 0.000 claims description 10
- 230000006835 compression Effects 0.000 claims description 7
- 238000007906 compression Methods 0.000 claims description 7
- 239000003949 liquefied natural gas Substances 0.000 abstract description 36
- 238000005265 energy consumption Methods 0.000 abstract description 10
- 239000002826 coolant Substances 0.000 abstract 2
- 238000001816 cooling Methods 0.000 abstract 1
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 238000004064 recycling Methods 0.000 abstract 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 239000003507 refrigerant Substances 0.000 description 6
- 238000005057 refrigeration Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000003345 natural gas Substances 0.000 description 3
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 206010000234 Abortion spontaneous Diseases 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 208000015994 miscarriage Diseases 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000012913 prioritisation Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 208000000995 spontaneous abortion Diseases 0.000 description 1
Classifications
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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
- F25J1/0025—Boil-off gases "BOG" from storages
-
- 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
- F25J1/0032—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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- 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
- F25J1/0201—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 only internal refrigeration means, i.e. without external refrigeration
- F25J1/0202—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 only internal refrigeration means, i.e. without external refrigeration in a quasi-closed internal refrigeration loop
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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.
- F25J1/0285—Combination of different types of drivers mechanically coupled to the same refrigerant compressor, possibly split on multiple compressor casings
- F25J1/0288—Combination 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
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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
- F25J2220/00—Processes or apparatus involving steps for the removal of impurities
- F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
- F25J2220/62—Separating 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 invention relates to a reliquefaction system and technique for compressing expanded liquified BOG through the BOG. The number of equipment is decreased, the cost is reduced, energy consumption is low, the starting and stopping response speed is high, the operating flexibility is high, the load varying capacity is high, and the application range is wide. The BOG generated through a liquefied natural gas (LNG) storage tank is subjected to cold quantity recycling through a heat exchanger and then enters a BOG buffer tank to be converged with BOG serving as a cooling agent. Then the BOG enters a BOG compressor. The compressed BOG is divided into two parts through a first cooler. The first part of BOG enters the heat exchanger to be further cooled and liquified and then enters a gas-liquid separator through a throttling valve to be subjected to gas-liquid separation. The second part of BOG serves as the cooling agent of the first part of the BOG. The second part of BOG is pressurized through a turbine expansion machine, then enters a second cooler for water cooling and enters the heat exchanger to be cooled, and enters the turbine expansion machine to be expanded. The expanded BOG returns to the heat exchanger to supply cold quantity while being reheated for entering the BOG buffer tank to be converged with the first part of BOG. Circulation is conducted in this way.
Description
Technical field
The present invention relates to a kind of liquefaction system again and the technique that adopt BOG self compression-expansion liquefaction BOG.
Background technology
Natural gas is as a kind of high-quality, the clean energy, and its calorific value is high, and environmental pollution is little, is considered to the following first-selected energy.Normal pressure liquefied natural gas (LNG) is as a kind of existence form of natural gas, and its volume is only equivalent to mark 1/625 of condition volume, is extremely conducive to transport and stores.Along with the world and China's expanding economy, grow with each passing day to Natural Gas Demand, LNG is subject to the favor of countries in the world with its very high economy, flexibility etc.Due to the condition of storage that LNG is special, produce a large amount of BOG gas in LNG liquefaction plant, LNG transfer station and LNG receiving station, main source is produce a large amount of BOG gas when natural evaporation and LNG tank car fill in LNG storage tank.In current liquefaction plant, BOG returns reliquefaction disposal in unstripped gas, but when liquefaction plant stops production, the BOG evaporated cannot process, if and do not configure reliquefaction disposal device in receiving station and transfer station, these BOG can only burn in emptying, while environment, waste a large amount of energy, cause the problems such as energy consumption is high.
The quality of BOG liquefaction process again will directly affect safety and the economic benefit of LNG accumulating.The BOG of current employing again liquefaction process roughly has two kinds: a kind of is nitrogen compression swell refrigeration technique, and this technique employing nitrogen is as cold-producing medium, and compression-expansion provides refrigerating capacity for BOG; This technique needs independently nitrogen kind of refrigeration cycle, and flow sheet equipment is many and complicated, and energy consumption is relatively high.The second adopts BOG direct condensation, and BOG is condensation again after mixing with the LNG carrying out self-pumping after BOG compressor compresses, utilizes the cold energy of the LNG exported from LNG storage tank; This process energy consumption is low, but is only applicable to situation when continuous LNG exports.
Application number be 201510167535.2 Chinese patent disclose a kind of BOG liquefaction process and recovery system that liquefies again thereof again, the cold adopting BOG self to compress deutomerite miscarriage raw in the process cooled BOG freezes to self, BOG is liquefied again, again collect in LNG storage tank, thus the cost adopting other refrigerant liquefaction BOG to bring can be avoided to increase.But the energy consumption of the technological process of this technical scheme and system unit volume BOG is very high (points out to be 3.45 ~ 7.655KW.h/Nm in patent
3), still have significant optimization space.
Summary of the invention
The object of the invention is to overcome above shortcomings in prior art, and the liquefaction system again providing a kind of self compression-expansion of employing BOG rational in infrastructure to liquefy BOG and technique, by adopting BOG self as cold-producing medium, only needing 1 normal temperature BOG compressor, 1 turbo-expander and 1 heat exchanger, significantly simplify flow process, decrease equipment, reduce cost, and energy consumption is low, start and stop fast response time, operating flexibility is large, varying duty ability is strong, applied widely.
The present invention's adopted technical scheme that solves the problem is: a kind of BOG self compression-expansion that adopts liquefies the liquefaction system again of BOG, it is characterized in that: LNG storage tank, BOG surge tank, BOG compressor, turbo-expander, heat exchanger, choke valve, gas-liquid separator, the first cooler and the second cooler;
Heat exchanger has first flow, the second runner, the 3rd runner and the 4th runner;
The BOG outlet of LNG storage tank is communicated with the cold-side inlet of the first flow of heat exchanger, and the outlet of the hot junction of the first flow of heat exchanger is communicated with the entrance of BOG surge tank; The outlet of BOG surge tank is communicated with the entrance of BOG compressor; The outlet of BOG compressor is communicated with the entrance of the first cooler;
The outlet of the first cooler is communicated with the hot-side inlet of the second runner of heat exchanger, and the cold side outlet of the second runner of heat exchanger is communicated with the entrance of choke valve, the outlet of choke valve is communicated with the entrance of gas-liquid separator, and the outlet of gas-liquid separator is communicated with the entrance of LNG storage tank;
The outlet of the first cooler is also communicated with the pressurized end entrance of turbo-expander, the pressurized end outlet of turbo-expander is communicated with the entrance of the second cooler, the outlet of the second cooler is communicated with the hot-side inlet of the 3rd runner of heat exchanger, and the cold side outlet of the 3rd runner of heat exchanger is communicated with the expanding end entrance of turbo-expander; The expanding end outlet of turbo-expander is communicated with the cold-side inlet of the 4th runner of heat exchanger, and the outlet of the hot junction of the 4th runner of heat exchanger is communicated with the entrance of BOG surge tank.
The present invention also comprises threeway; The outlet of the first cooler and three general pipeline communications, two outlets of threeway are communicated with the pressurized end entrance of turbo-expander with the hot-side inlet of the second runner of heat exchanger respectively.
First cooler of the present invention and the second cooler are water cooler.
Adopt a liquefaction process again of BOG self compression-expansion liquefaction BOG, it is characterized in that: adopt above-mentioned system to process;
The BOG that LNG storage tank evaporates first reclaims cold re-heat to 15 ~ 30 DEG C through heat exchanger, the BOG as cryogen entering BOG surge tank and same re-heat to 15 ~ 30 DEG C again converges, then enter BOG compressor compresses to 600 ~ 1000Kpa.A, the BOG after compression is divided into two parts after the first cooler is cooled to 35 ~ 40 DEG C;
Part I BOG to enter in heat exchanger cooled liquefaction further to-150 ~-155 DEG C, after after choke valve throttling, enter gas-liquid separator to 120Kpa.A carry out gas-liquid separation, the gas emptying that isolated nitrogen content is high, liquid enters LNG storage tank and stores;
Part II is used as the cryogen of Part I, the BOG of this part is first pressurized to 1000 ~ 1200Kpa.A through the pressurized end of turbo-expander, behind the second cooler water-cooled to 35 ~ 40 DEG C, enter heat exchanger again and be cooled to-95 ~-110 DEG C, the expanding end entering turbo-expander be again expanded to 130 ~ 150Kpa.A ,-155 ~-160 DEG C, BOG after expansion returns heat exchanger provides cold to be converged by the BOG entering BOG surge tank and Part I behind re-heat to 15 ~ 30 DEG C simultaneously, so circulates.
The liquefaction process again of employing BOG self compression-expansion liquefaction BOG of the present invention, is characterized in that:
The BOG that LNG storage tank evaporates first reclaims cold re-heat to 20 DEG C through heat exchanger, the BOG as cryogen entering BOG surge tank and same re-heat to 20 DEG C again converges, then enter BOG compressor compresses to 700Kpa, the BOG after compression is divided into two parts after the first cooler is cooled to 40 DEG C;
Part I BOG to enter in heat exchanger cooled liquefaction further to-152 DEG C, after after choke valve throttling, enter gas-liquid separator to 120Kpa carry out gas-liquid separation, the gas emptying that isolated nitrogen content is high, liquid enters LNG storage tank and stores;
Part II is used as the cryogen of Part I, the BOG of this part is first pressurized to 1080Kpa through the pressurized end of turbo-expander, after the second cooler water-cooled to 40 DEG C, enter heat exchanger again and be cooled to-100 DEG C, the expanding end entering turbo-expander is again expanded to 130Kpa and-160 DEG C, BOG after expansion returns heat exchanger provides cold to be converged by the BOG entering BOG surge tank and Part I after re-heat to 20 DEG C simultaneously, so circulates.
The present invention compared with prior art, has the following advantages and effect:
1, cold-producing medium of the present invention adopts BOG itself, without the need to extra cryogen and cryogen preparation facilities, decreases the configuration of cryogen storage tank in kind of refrigeration cycle, decrease extra refrigerant compressor, only need the BOG compressor of 1 normal temperature, make whole flow process more simple, investment more economizes.
2, the pressure after BOG compressor compresses of the present invention is 700Kpa, can adopt helical-lobe compressor, reliability is high, the life-span is long, automaticity is high, strong adaptability, reduced investment; And in LNG liquefaction plant, also can utilize original BOG compressor, without the need to additional configuration.
3, flow process of the present invention is simple, and equipment is few, only has 1 normal temperature BOG compressor, 1 BOG turbo-expander, 1 heat exchanger, 1 choke valve and flash tank, reduced investment, good economy performance and can realize skid.
4, gas emptying after throttling, avoids the gathering of nitrogen content in whole technique stream and increases energy consumption.
5, the present invention divides two parts after compressing, a part is for needing the BOG amount of liquefaction, a part is for entering the refrigerant amount of turbo-expander, can according to the situation of BOG amount and component in actual items, after adjusting the refrigerant amount or adjustment turbo-expander machine entering turbo-expander, pressure is to meet the requirement of refrigerating capacity, make it the requirement and the varying duty production that meet disparity items different B OG amount, operate simply easy to adjust, adaptability is good.
6, this flow process adopts turbine expander refrigeration, makes full use of the feature of decompressor high pressure, high enthalpy drop, reduces energy consumption; Make full use of the output work of decompressor, expand after making cryogen BOG continue supercharging, improve refrigerating capacity;
7, the BOG that evaporates of storage tank is by entering compressor after heat exchanger re-heat, avoid the waste of cold, reduce energy consumption, and compressor can adopt normal temperature compressed machine, greatly reduces cost.
Therefore, the present invention has that flow process is simple, floor space is little, reduced investment, and plant energy consumption is low, and operating flexibility is large, and varying duty ability is strong, applied widely, is easy to do the advantages such as sled block, is particularly useful for LNG receiving station or has the LNG liquefaction plant of unnecessary BOG.
Accompanying drawing explanation
Fig. 1 is the structural representation of embodiment of the present invention system.
Detailed description of the invention
Below in conjunction with accompanying drawing, also by embodiment, the present invention is described in further detail, and following examples are explanation of the invention and the present invention is not limited to following examples.
See Fig. 1, the embodiment of the present invention adopts the liquefaction system again of BOG self compression-expansion liquefaction BOG to comprise LNG storage tank 1, BOG surge tank 2, BOG compressor 3, turbo-expander 4, heat exchanger 5, choke valve 6, gas-liquid separator 7, first cooler 8 and the second cooler 9.
Heat exchanger 5 has first flow, the second runner, the 3rd runner and the 4th runner.
First cooler and the second cooler are water cooler.
The BOG outlet of LNG storage tank 1 and the cold-side inlet pipeline communication of the first flow of heat exchanger 5, and the entrance pipeline communication of the outlet of the hot junction of the first flow of heat exchanger 5 and BOG surge tank 2; The outlet of BOG surge tank 2 and the entrance pipeline communication of BOG compressor 3; The outlet of BOG compressor 3 and the entrance pipeline communication of the first cooler 8.
The hot-side inlet pipeline communication of the outlet of the first cooler 8 and the second runner of heat exchanger 5, and the cold side outlet of the second runner of heat exchanger 5 and the entrance pipeline communication of choke valve 6, the outlet of choke valve 6 and the entrance pipeline communication of gas-liquid separator 7, the outlet of gas-liquid separator 7 and the entrance pipeline communication of LNG storage tank 1.
The outlet of the first cooler 8 also with the pressurized end entrance pipeline communication of turbo-expander 4, the pressurized end outlet of turbo-expander 4 and the entrance pipeline communication of the second cooler 9, the hot-side inlet pipeline communication of the outlet of the second cooler 9 and the 3rd runner of heat exchanger 5, and the cold side outlet of the 3rd runner of heat exchanger 5 and the expanding end entrance pipeline communication of turbo-expander 4; The expanding end outlet of turbo-expander 4 and the cold-side inlet pipeline communication of the 4th runner of heat exchanger 5, and the entrance pipeline communication of the outlet of the hot junction of the 4th runner of heat exchanger 5 and BOG surge tank 2.
The outlet of the first cooler 8 and three general pipeline communications, and two of threeway outlets respectively with the hot-side inlet of the second runner of heat exchanger 5 and the pressurized end entrance pipeline communication of turbo-expander 4, the outlet of such first cooler 8 just respectively with the hot-side inlet of the second runner of heat exchanger 5 and the pressurized end entrance pipeline communication of turbo-expander 4.
The present invention adopts the liquefaction process again of BOG self compression-expansion liquefaction BOG as follows:
The BOG pressure that LNG storage tank 1 evaporates is 120Kpa.A, temperature is-140 ~-160 DEG C, this BOG first reclaims cold re-heat to 15 ~ 30 DEG C through heat exchanger 5, the cryogen BOG entering BOG surge tank 2 and same re-heat to 15 ~ 30 DEG C again converges, then enter BOG compressor 3 and be compressed to 600 ~ 1000Kpa.A, the BOG after compression is divided into two parts after the first cooler 8 is cooled to 35 ~ 40 DEG C.
The flow of Part I BOG is the BOG amount for LNG storage tank 1 evaporates, pressure is 600 ~ 1000Kpa.A, temperature is 35 ~ 40 DEG C, this part i.e. the BOG BOG amount flashed off from LNG storage tank 1 per hour, this part BOG enters cooled liquefaction extremely-150 ~-155 DEG C further in heat exchanger 5, after after choke valve 6 throttling, enter gas-liquid separator 7 to 120Kpa carry out gas-liquid separation, the gas emptying that isolated nitrogen content is high, liquid enters LNG storage tank 1 and stores.
Part II is used as the cryogen of Part I, its flow of the BOG of this part is 6 ~ 9 times that Part I BOG measures, pressure is 600 ~ 1000Kpa.A, temperature is 35 ~ 40 DEG C, this part BOG is first pressurized to 1000 ~ 1200Kpa.A through the pressurized end of turbo-expander 4, behind the second cooler 9 water-cooled to 35 ~ 40 DEG C, enter heat exchanger 5 again and be cooled to-95 ~-110 DEG C, the expanding end entering turbo-expander 4 is again expanded to 130 ~ 150Kpa.A,-155 ~-160 DEG C, BOG after expansion returns heat exchanger 5 and provides cold simultaneously to be entered BOG surge tank 2 behind re-heat to 15 ~ 30 DEG C to converge with the BOG of Part I, circulation like this.
Cold-producing medium needed for above-mentioned expansion flow process, after BOG compressor, during driving, first with the pressurized end introducing turbo-expander 4 from the gas after BOG compressor, reach after refrigeration requirement wait the required refrigerant amount that expands, regulate the valve that BOG compressor 3 goes turbo-expander 4 supercharging to contract.BOG amount is when changing, and meets the requirement of refrigerating capacity by pressure after the temperature of cryogen BOG after the amount of cold-producing medium BOG after regulating normal temperature BOG compressor and heat exchanger and turbo-expander.
The embodiment of the present invention adopts the prioritization scheme of liquefaction process again of BOG self compression-expansion liquefaction BOG as follows:
Its flow of the BOG that LNG storage tank 1 evaporates is 800Nm
3/ h, pressure are 120Kpa.A, temperature is-140 DEG C, this BOG first reclaims cold re-heat to 20 DEG C through heat exchanger 5, the cryogen BOG entering BOG surge tank 2 and same re-heat to 20 DEG C again converges, then enter BOG compressor 3 and be compressed to 700Kpa, the BOG after compression is divided into two parts after the first cooler 8 is cooled to 40 DEG C.
The flow of Part I BOG is 800Nm
3/ h, pressure are 700Kpa.A, temperature is 40 DEG C, this part i.e. the BOG BOG amount flashed off from LNG storage tank 1 per hour, this part BOG enters cooled liquefaction extremely-152 DEG C further in heat exchanger 5, after after choke valve 6 throttling, enter gas-liquid separator 7 to 120Kpa carry out gas-liquid separation, the gas emptying that isolated nitrogen content is high, liquid enters LNG storage tank 1 and stores.
Part II is used as the cryogen of Part I, and its flow of the BOG of this part is 5800Nm
3/ h, pressure are 700Kpa.A, temperature is 40 DEG C, this part BOG is first pressurized to 1080Kpa through the pressurized end of turbo-expander 4, after the second cooler 9 water-cooled to 40 DEG C, enter heat exchanger 5 again and be cooled to-100 DEG C, the expanding end entering turbo-expander 4 be again expanded to 130Kpa ,-160 DEG C, BOG after expansion returns heat exchanger 5 and provides cold simultaneously to be entered BOG surge tank 2 after re-heat to 20 DEG C to converge with the BOG of Part I, so circulate.
Cold-producing medium needed for above-mentioned expansion flow process, after BOG compressor, during driving, first with the pressurized end introducing turbo-expander 4 from the gas after BOG compressor, reach after refrigeration requirement wait the required refrigerant amount that expands, regulate the valve that BOG compressor 3 goes turbo-expander 4 supercharging to contract.BOG amount is when changing, and meets the requirement of refrigerating capacity by pressure after the temperature of cryogen BOG after the amount of cold-producing medium BOG after regulating normal temperature BOG compressor and heat exchanger and turbo-expander.
In addition, it should be noted that, the specific embodiment described in this description, the shape, institute's title of being named etc. of its parts and components can be different, and the above content described in this description is only to structure example of the present invention explanation.
Claims (5)
1. adopt a liquefaction system again of BOG self compression-expansion liquefaction BOG, it is characterized in that: LNG storage tank, BOG surge tank, BOG compressor, turbo-expander, heat exchanger, choke valve, gas-liquid separator, the first cooler and the second cooler;
Heat exchanger has first flow, the second runner, the 3rd runner and the 4th runner;
The BOG outlet of LNG storage tank is communicated with the cold-side inlet of the first flow of heat exchanger, and the outlet of the hot junction of the first flow of heat exchanger is communicated with the entrance of BOG surge tank; The outlet of BOG surge tank is communicated with the entrance of BOG compressor; The outlet of BOG compressor is communicated with the entrance of the first cooler;
The outlet of the first cooler is communicated with the hot-side inlet of the second runner of heat exchanger, and the cold side outlet of the second runner of heat exchanger is communicated with the entrance of choke valve, the outlet of choke valve is communicated with the entrance of gas-liquid separator, and the outlet of gas-liquid separator is communicated with the entrance of LNG storage tank;
The outlet of the first cooler is also communicated with the pressurized end entrance of turbo-expander, the pressurized end outlet of turbo-expander is communicated with the entrance of the second cooler, the outlet of the second cooler is communicated with the hot-side inlet of the 3rd runner of heat exchanger, and the cold side outlet of the 3rd runner of heat exchanger is communicated with the expanding end entrance of turbo-expander; The expanding end outlet of turbo-expander is communicated with the cold-side inlet of the 4th runner of heat exchanger, and the outlet of the hot junction of the 4th runner of heat exchanger is communicated with the entrance of BOG surge tank.
2. the liquefaction system again of employing BOG self compression-expansion liquefaction BOG according to claim 1, is characterized in that: also comprise threeway; The outlet of the first cooler and three general pipeline communications, two outlets of threeway are communicated with the pressurized end entrance of turbo-expander with the hot-side inlet of the second runner of heat exchanger respectively.
3. the liquefaction system again of employing BOG self compression-expansion liquefaction BOG according to claim 1 and 2, is characterized in that: the first described cooler and the second cooler are water cooler.
4. adopt a liquefaction process again of BOG self compression-expansion liquefaction BOG, it is characterized in that: adopt the system described in the arbitrary claim of claims 1 to 3 to process;
The BOG that LNG storage tank evaporates first reclaims cold re-heat to 15 ~ 30 DEG C through heat exchanger, the BOG as cryogen entering BOG surge tank and same re-heat to 15 ~ 30 DEG C again converges, then enter BOG compressor compresses to 600 ~ 1000Kpa.A, the BOG after compression is divided into two parts after the first cooler is cooled to 35 ~ 40 DEG C;
Part I BOG to enter in heat exchanger cooled liquefaction further to-150 ~-155 DEG C, after after choke valve throttling, enter gas-liquid separator to 120Kpa.A carry out gas-liquid separation, the gas emptying that isolated nitrogen content is high, liquid enters LNG storage tank and stores;
Part II is used as the cryogen of Part I, the BOG of this part is first pressurized to 1000 ~ 1200Kpa.A through the pressurized end of turbo-expander, behind the second cooler water-cooled to 35 ~ 40 DEG C, enter heat exchanger again and be cooled to-95 ~-110 DEG C, the expanding end entering turbo-expander be again expanded to 130 ~ 150Kpa.A ,-155 ~-160 DEG C, BOG after expansion returns heat exchanger provides cold to be converged by the BOG entering BOG surge tank and Part I behind re-heat to 15 ~ 30 DEG C simultaneously, so circulates.
5. the liquefaction process again of employing BOG self compression-expansion liquefaction BOG according to claim 4, is characterized in that:
The BOG that LNG storage tank evaporates first reclaims cold re-heat to 20 DEG C through heat exchanger, the BOG as cryogen entering BOG surge tank and same re-heat to 20 DEG C again converges, then enter BOG compressor compresses to 700Kpa, the BOG after compression is divided into two parts after the first cooler is cooled to 40 DEG C;
Part I BOG to enter in heat exchanger cooled liquefaction further to-152 DEG C, after after choke valve throttling, enter gas-liquid separator to 120Kpa carry out gas-liquid separation, the gas emptying that isolated nitrogen content is high, liquid enters LNG storage tank and stores;
Part II is used as the cryogen of Part I, the BOG of this part is first pressurized to 1080Kpa through the pressurized end of turbo-expander, after the second cooler water-cooled to 40 DEG C, enter heat exchanger again and be cooled to-100 DEG C, the expanding end entering turbo-expander is again expanded to 130Kpa and-160 DEG C, BOG after expansion returns heat exchanger provides cold to be converged by the BOG entering BOG surge tank and Part I after re-heat to 20 DEG C simultaneously, so circulates.
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| CN113339082A (en) * | 2021-06-30 | 2021-09-03 | 上海康恒环境股份有限公司 | Low-temperature cold energy recovery power generation system |
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| CN114017988A (en) * | 2021-12-01 | 2022-02-08 | 上海齐耀动力技术有限公司 | BOG (boil-off gas) reliquefaction circulation system for LNG (liquefied Natural gas) ship based on mixed working medium refrigeration technology |
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