CN110487023A - A method of liquid nitrogen is produced using LNG cold energy - Google Patents

A method of liquid nitrogen is produced using LNG cold energy Download PDF

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Publication number
CN110487023A
CN110487023A CN201910739821.XA CN201910739821A CN110487023A CN 110487023 A CN110487023 A CN 110487023A CN 201910739821 A CN201910739821 A CN 201910739821A CN 110487023 A CN110487023 A CN 110487023A
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nitrogen
liquid nitrogen
sent
lng
heat exchanger
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CN110487023B (en
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王军辉
施俊丰
张菁菁
彭荣梅
杨荣
周雯
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Zhejiang Zhihai Chemical Equipment Engineering Co Ltd
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Zhejiang Zhihai Chemical Equipment 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
    • F25J1/0012Primary atmospheric gases, e.g. air
    • F25J1/0015Nitrogen
    • 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
    • F25J1/003Processes 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"
    • F25J1/0045Processes 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 vaporising a liquid 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
    • F25J1/0221Processes 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 the cold stored in an external cryogenic component in an open 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
    • F25J1/0221Processes 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 the cold stored in an external cryogenic component in an open refrigeration loop
    • F25J1/0224Processes 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 the cold stored in an external cryogenic component in an open refrigeration loop in combination with an internal quasi-closed 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
    • F25J2210/00Processes characterised by the type or other details of the feed stream
    • F25J2210/62Liquefied natural gas [LNG]; Natural gas liquids [NGL]; Liquefied petroleum gas [LPG]
    • 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
    • F25J2270/00Refrigeration techniques used
    • F25J2270/04Internal refrigeration with work-producing gas expansion loop
    • F25J2270/06Internal refrigeration with work-producing gas expansion loop with multiple gas expansion loops
    • 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
    • F25J2290/00Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/34Details about subcooling of liquids

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Separation By Low-Temperature Treatments (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

A method of liquid nitrogen is produced using LNG cold energy, this method is: LNG is sent into heat exchanger after liquid pump is compressed and nitrogen exchanges heat, it is sent into BOG compressor boost after re-heat to lower temperature and is ultimately delivered to NG pipe network, nitrogen from pipe network or recycle compressor is divided into two strands: one first passes through the pressurization cooling of expanding machine pressurized end, subsequently into being drawn to expander after being cooled to certain temperature in main heat exchanger, nitrogen after expansion is again introduced into the pressurization cooling of expanding machine pressurized end after re-heat to room temperature, and it is cooling to return to the main heat exchanger in liquefier, to be lowered to pumping into expander in after certain temperature, low-pressure nitrogen after expansion returns heat exchanger re-heat, nitrogen circulation compressor cycle is directly vented or is sent into after cooling box;One is sent directly into heat exchanger and LNG exchanges heat, after being cooled to target temperature and being condensed into liquid nitrogen, liquid nitrogen is divided into two parts: one liquid nitrogen is sent into subcooler after throttling to low pressure and liquid nitrogen is subcooled, and the low pressure liquid nitrogen after evaporation is vented or returns circulating nitrogen gas compressor cycle through main heat exchanger re-heat;Secondly the liquid nitrogen by supercooling, which directly throttles, is sent into liquid nitrogen storage.

Description

A method of liquid nitrogen is produced using LNG cold energy
Technical field
The present invention relates to a kind of method using LNG cold energy production liquid nitrogen, be primarily adapted for use in by air and liquid nitrogen into Row liquefaction, the liquid products such as production liquid nitrogen, belongs to Cryogenic air separation technical field.
Background technique
With national energy structural adjustment and the implementation of energy-saving and emission-reduction policy, replaced using the energy of more high-efficiency cleaning Traditional energy Efforts To Develop.Natural gas is as one of clean energy resource, and easy-to-use because of its energy density height, pollution is small, Consumption figure is increasing.According to the economic trend and relevant law and policy of country, China's natural gas demand from now on Potentiality will further expansion.By the development of nearly more than ten years, domestic natural gas supply at present has formed more gas source supply patterns, Basically formed more complete LNG industry chain, especially develop in terms of LNG receiving station in recent years it is very swift and violent, LNG into Mouth amount rapid growth, increases by 52% every year.
When natural gas is cooled to about 1 DEG C under atmospheric pressure, liquid, i.e. LNG are transformed by gaseous state.LNG is a kind of nothing Color transparency liquid, main component are methane, and LNG volume is about the l/625 of the standard gaseous natural gas volume of homogenous quantities, and density is 450kg/nf has the characteristics that energy storage rate is high, takes up an area less, is with low investment.LNG includes 30% high-grade cold energy, with LNG The continuous expansion of scale, LNG contain the making full use of with extremely important economic value and social effect of cold energy.
Current LNG cold energy use both at home and abroad relies primarily on air separation, lighter hydrocarbons separation, low-temperature electricity-generating, sea water desalination, dioxy Change carbon capture, waste old low-temperature grinding, refrigeration etc..Wherein the cold energy quality of LNG cold energy and Cryogenic air separation technology is the most It is close, it is generally acknowledged preferable mode, as reasonable utilization can significantly reduce air separation unit liquid product (liquid nitrogen) The cost of the cryogenic liquids product such as liquid nitrogen, liquid oxygen can be greatly lowered in production energy consumption.
Patent ZL200810121860.5 proposes one kind by low temperature nitrogen circulator, nitrogen turbo compressor, natural gas Heat exchanger, high temperature pressurised turbo-expander, low-temperature turbine boosting expansion machine, vapour liquid separator and liquid nitrogen subcooler form liquid nitrogen The electric consumption of process units and method, production 1kg liquid nitrogen is only 0.24kwh.Although method and device described in method has Higher LNG cold energy use efficiency, but because compressor, supercharger etc. all use low temperature air inlet mode, cause technology not nearly enough at It is ripe, and equipment cost is extremely expensive.
Patent ZL201410616943.7 proposes a kind of nitrogen gas liquefaction system for recycling LNG cold energy, which adopts It is simple that a kind of structure is intended to provide with a nitrogen circulation compressor, and cold energy use rate is high, can reduce nitrogen compressor pressure etc. Grade and heat exchanger pressure rating, the nitrogen gas liquefaction system of energy saving.The system equipment is simple, and technology maturation is reliable, but in reality There are LNG cold energy use rate is low in the application of border.
Summary of the invention
It is an object of the invention to overcome the shortcomings of the prior art, and a kind of technology maturation being provided, equipment is cheap, and And the high method using LNG cold energy production liquid nitrogen of LNG cold energy use rate.
The object of the present invention is achieved by the following technical solutions, a kind of side using LNG cold energy production liquid nitrogen Method, this method are: LNG is sent into heat exchanger after liquid pump is compressed and nitrogen exchanges heat, and BOG pressure is sent into after re-heat to lower temperature The pressurization of contracting machine is ultimately delivered to NG pipe network, and the nitrogen from pipe network or recycle compressor is divided into two strands: one first passes through expanding machine increasing Pressure side pressurization cooling, is drawn to expander subsequently into being cooled to after certain temperature in main heat exchanger, the nitrogen after expansion It is again introduced into the pressurization cooling of expanding machine pressurized end after re-heat to room temperature, and returns to the cooling of the main heat exchanger in liquefier, to It is reduced to the low-pressure nitrogen pumped in after certain temperature into expander, after expansion to return heat exchanger re-heat, it is straight after cooling box It connects emptying or is sent into nitrogen circulation compressor cycle;One is sent directly into heat exchanger and LNG and exchanges heat, and is cooled to target temperature and cold After congealing into liquid nitrogen, liquid nitrogen is divided into two parts: one liquid nitrogen is sent into subcooler after throttling to low pressure and liquid nitrogen is subcooled, and evaporates Low pressure liquid nitrogen afterwards is vented or returns circulating nitrogen gas compressor cycle through main heat exchanger re-heat;Secondly the liquid nitrogen by supercooling directly saves It streams into liquid nitrogen storage.
The present invention compresses low temperature NG using low temperature BOG compressor, it is ensured that the cold energy quality of LNG significantly obtains BOG Power consumption of compressor.
The present invention is connected using the pressuring expansion of high and low temperature expanding machine, so that heat exchanger heat transfer temperature difference is rationally to greatest extent LNG cold energy use efficiency, and the ability of the adaptive LNG change of component of energy are improved, off-design efficiency is greatly improved;
The present invention avoids expensive and poor reliability low temperature nitrogen using conventional products nitrogen compressor as recycle compressor The use of centrifugal compressor, is greatly lowered equipment investment, and reliability increases substantially;
In method of the present invention using LNG cold energy production liquid nitrogen, it is 0.3kwh/Nm3 that it is more excellent, which to obtain liquid nitrogen specific energy consumption, for production, Liquid nitrogen specific energy consumption than the production of conventional liquefying plant is low by 50% or more;Method of the invention not only significantly reduces liquid nitrogen unit Energy consumption, and equipment investment can be greatly lowered, improve equipment dependability.
Detailed description of the invention
Fig. 1 is a kind of of the present invention, flow diagram using LNG production liquid nitrogen.
Specific embodiment
Below in conjunction with specific embodiment, the present invention is described in detail, a kind of utilization LNG cold energy of the present invention The method for producing liquid nitrogen, this method is: LNG is sent into heat exchanger after liquid pump is compressed and nitrogen exchanges heat, and re-heat is to compared with low temperature It is sent into BOG compressor boost after degree and is ultimately delivered to NG pipe network, the nitrogen from pipe network or recycle compressor is divided into two strands: one elder generation It is pressurized and cools down by expanding machine pressurized end, subsequently into being drawn to expander after being cooled to certain temperature in main heat exchanger, Nitrogen after expansion is again introduced into the pressurization cooling of expanding machine pressurized end after re-heat to room temperature, and returns to the master in liquefier and change Hot device is cooling, returns heat exchanger re-heat, In to be lowered to the low-pressure nitrogen pumped into expander, after expansion in after certain temperature Nitrogen circulation compressor cycle is directly vented or is sent into after cooling box;One is sent directly into heat exchanger and LNG exchanges heat, and is cooled to mesh Mark temperature and after being condensed into liquid nitrogen, liquid nitrogen are divided into two parts: one liquid nitrogen be sent into after throttling to low pressure in subcooler to liquid nitrogen into Row supercooling, the low pressure liquid nitrogen after evaporation are vented or return circulating nitrogen gas compressor cycle through main heat exchanger re-heat;Secondly by supercooling Liquid nitrogen directly throttle be sent into liquid nitrogen storage.
The present invention is configured with low temperature BOG compressor, and the main heat exchanger re-heat being sent into liquefaction ice chest after LNG pump compression is multiple It is sent into BOG compressor compresses after heat to 0-130 DEG C of low temperature of temperature range, and is ultimately delivered to NG pipe network;It is led when LNG stream amount is larger When refrigerating capacity is more, the temperature of NG feeding BOG compressor is reduced to reduce the consumption of BOG compressor, while reducing nitrogen compression The load of machine and expanding machine, to reduce liquid nitrogen specific energy consumption.
The present invention is configured with conventional products nitrogen compressor and high/low temperature expanding machine, and expanding machine process is the increasing of tandem Pressure, expansion, pressurization, expansion, the Load Regulation of each unit is determined according to whether LNG cooling capacity is sufficient, as flow or component become LNG cooling capacity caused by changing is sufficient, then can suitably reduce the load of each unit, to reduce liquid nitrogen specific energy consumption, on the contrary LNG cold Amount is insufficient, then should increase each unit load to supplement the cooling capacity of liquid nitrogen product.
In the method, low temperature BOG compressor inlet temperature range is 20 ~ -130 DEG C, is -40 DEG C compared with the figure of merit, specifically It is matched according to the cooling capacity of LNG;Inlet pressure range is 1-3bar, is 1.6bar compared with the figure of merit;Pressure at expulsion is used according to terminal The matching of gas situation;
In the method, the pressure at expulsion range of circulating nitrogen gas compressor is 24-30bar, is 27bar, entrance pressure compared with the figure of merit Power and capacity are matched according to LNG cooling capacity and liquid yield;
In the method, each stage pressure of high/low temperature expanding machine, temperature and flow are according to LNG cooling capacity and liquid yield progress Match;
It in the method, when LNG component, flow change, is matched, is become by adjusting expanding machine, nitrogen compressor parameter Open adjusting can be carried out when changing larger by start-stop expanding machine.
Embodiment: shown in Fig. 1, a kind of method using LNG cold energy production liquid nitrogen of the present invention, this method is: LNG is sent into heat exchanger and nitrogen after liquid pump P1 is compressed to 1.6bar and exchanges heat, and re-heat is to after about -40 degrees Celsius of lower temperature It is sent into BOG compressor boost and is ultimately delivered to NG pipe network.It is divided into two from the nitrogen that pipe network or recycle compressor pressure are 27bar Stock: one 01 first passes through the pressurization cooling of expanding machine pressurized end, subsequently into being drawn to after being cooled to certain temperature in main heat exchanger Expander, the nitrogen after expansion are again introduced into the pressurization cooling of expanding machine pressurized end, and rework solution after re-heat to room temperature The main heat exchanger changed in device is cooling, returns to be lowered to the low-pressure nitrogen pumped into expander, after expansion in after certain temperature Heat exchanger re-heat is directly vented or is sent into nitrogen circulation compressor cycle after cooling box;One 02 be sent directly into heat exchanger with LNG heat exchange, after being cooled to target temperature and being condensed into liquid nitrogen, liquid nitrogen is divided into two parts: 04 liquid nitrogen of one is sent after throttling to low pressure Enter in subcooler and liquid nitrogen is subcooled, the low pressure liquid nitrogen after evaporation is vented or returns circulating nitrogen gas compressor through main heat exchanger re-heat Circulation;Secondly 03 liquid nitrogen by supercooling, which directly throttles, is sent into liquid nitrogen storage.
In the method, if the variation of LNG stream amount causes cooling capacity sufficient, then the suction port of compressor low temperature BOG temperature is suitably reduced Degree, inlet temperature that is on the contrary then properly increasing BOG compressor;If LNG change of component causes cooling capacity sufficient, then can only suitably reduce Nitrogen compressor and the load for expanding unit, it is on the contrary then need to increase corresponding load.
In the method, the circulating nitrogen gas compressor inlet temperature used is room temperature, it is necessary to ensure that inlet temperature is at 0 DEG C More than, guarantee equipment safety;The outlet pressure of nitrogen compressor can be with appropriate adjustment;It, can be with when being varied widely such as operating condition Start-stop high and low temperature expanding machine appropriate is to adapt to operating condition variation.

Claims (3)

1. a kind of method using LNG cold energy production liquid nitrogen, it is characterised in that this method is: LNG is sent after liquid pump is compressed Enter heat exchanger and nitrogen to exchange heat, BOG compressor boost be sent into after re-heat to lower temperature and is ultimately delivered to NG pipe network, from pipe network or The nitrogen of recycle compressor is divided into two strands: one first passes through the pressurization cooling of expanding machine pressurized end, subsequently into cold in main heat exchanger But to expander is drawn to after certain temperature, the nitrogen after expansion is again introduced into expanding machine pressurization after re-heat to room temperature End pressurization cooling, and it is cooling to return to the main heat exchanger in liquefier, to be lowered to pumping into expander in after certain temperature, Low-pressure nitrogen after expansion returns heat exchanger re-heat, is directly vented or is sent into nitrogen circulation compressor cycle after cooling box;One It is sent directly into heat exchanger and LNG exchanges heat, after being cooled to target temperature and being condensed into liquid nitrogen, liquid nitrogen is divided into two parts: one liquid nitrogen It is sent into subcooler after throttling to low pressure and liquid nitrogen is subcooled, the low pressure liquid nitrogen after evaporation is vented or returns through main heat exchanger re-heat Circulating nitrogen gas compressor cycle;Secondly the liquid nitrogen by supercooling, which directly throttles, is sent into liquid nitrogen storage.
2. the method according to claim 1 using LNG cold energy production liquid nitrogen, it is characterised in that: be configured with low temperature BOG pressure Contracting machine, the main heat exchanger re-heat being sent into liquefaction ice chest after LNG pump compression, is sent into after re-heat to 0-130 DEG C of low temperature of temperature range BOG compressor compresses, and it is ultimately delivered to NG pipe network;When LNG stream amount is larger causes cooling capacity more, reduces NG and be sent into BOG compression The temperature of machine reduces the load of nitrogen compressor and expanding machine to reduce the consumption of BOG compressor, to reduce liquid nitrogen unit Energy consumption.
3. the method according to claim 1 or 2 using LNG cold energy production liquid nitrogen, it is characterised in that: be configured with conventional production Product nitrogen compressor and high/low temperature expanding machine, and expanding machine process is pressurization, expansion, pressurization, the expansion of tandem, each unit Load Regulation be to be determined according to whether LNG cooling capacity sufficient, the LNG cooling capacity as caused by flow or change of component is sufficient, then can be with The load of each unit is suitably reduced, to reduce liquid nitrogen specific energy consumption, otherwise LNG cooling capacity is insufficient, then it is negative should to increase each unit Lotus is to supplement the cooling capacity of liquid nitrogen product.
CN201910739821.XA 2019-08-12 2019-08-12 Method for producing liquid nitrogen by utilizing LNG cold energy Active CN110487023B (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115751838A (en) * 2022-11-02 2023-03-07 广东粤豫科技有限公司 Energy-saving liquefaction system and energy-saving nitrogen liquefier device

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Publication number Priority date Publication date Assignee Title
US5139547A (en) * 1991-04-26 1992-08-18 Air Products And Chemicals, Inc. Production of liquid nitrogen using liquefied natural gas as sole refrigerant
FR2805034A1 (en) * 2000-02-11 2001-08-17 Air Liquide Nitrogen liquefaction process involves compressing nitrogen to supercritical pressure, cooling by heat exchange with flow of liquefied natural gas in primary exchanger, expanded to specific pressure and liquefying
AU2009100992A4 (en) * 2009-09-30 2009-11-05 Jayaram, Narsimhan Mr LPG / LNG floating production unit, using a novel direct injected, single nitrogen expanded refrigeration cycle
CN101614464A (en) * 2008-06-23 2009-12-30 杭州福斯达实业集团有限公司 Method for liquefying natural gas through double-expansion of high-temperature and low-temperature nitrogen gas
US20140352353A1 (en) * 2013-05-28 2014-12-04 Robert S. Wissolik Natural Gas Liquefaction System for Producing LNG and Merchant Gas Products
CN106288650A (en) * 2015-06-26 2017-01-04 上海恩图能源科技有限公司 Nitrogen at room reclaims LNG cold energy technique

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5139547A (en) * 1991-04-26 1992-08-18 Air Products And Chemicals, Inc. Production of liquid nitrogen using liquefied natural gas as sole refrigerant
FR2805034A1 (en) * 2000-02-11 2001-08-17 Air Liquide Nitrogen liquefaction process involves compressing nitrogen to supercritical pressure, cooling by heat exchange with flow of liquefied natural gas in primary exchanger, expanded to specific pressure and liquefying
CN101614464A (en) * 2008-06-23 2009-12-30 杭州福斯达实业集团有限公司 Method for liquefying natural gas through double-expansion of high-temperature and low-temperature nitrogen gas
AU2009100992A4 (en) * 2009-09-30 2009-11-05 Jayaram, Narsimhan Mr LPG / LNG floating production unit, using a novel direct injected, single nitrogen expanded refrigeration cycle
US20140352353A1 (en) * 2013-05-28 2014-12-04 Robert S. Wissolik Natural Gas Liquefaction System for Producing LNG and Merchant Gas Products
CN106288650A (en) * 2015-06-26 2017-01-04 上海恩图能源科技有限公司 Nitrogen at room reclaims LNG cold energy technique

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115751838A (en) * 2022-11-02 2023-03-07 广东粤豫科技有限公司 Energy-saving liquefaction system and energy-saving nitrogen liquefier device
CN115751838B (en) * 2022-11-02 2024-01-02 广东粤豫科技有限公司 Energy-saving external liquefaction system and energy-saving nitrogen and oxygen external liquefier device

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