CN113137828A - System and method for preparing oxygen enrichment by using liquefied natural gas terminal cold energy - Google Patents

System and method for preparing oxygen enrichment by using liquefied natural gas terminal cold energy Download PDF

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CN113137828A
CN113137828A CN202010050238.0A CN202010050238A CN113137828A CN 113137828 A CN113137828 A CN 113137828A CN 202010050238 A CN202010050238 A CN 202010050238A CN 113137828 A CN113137828 A CN 113137828A
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air
oxygen
pipe
heat exchanger
natural gas
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赖家俊
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04012—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of warm gaseous streams; details of intake or interstage cooling
    • F25J3/04018—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of warm gaseous streams; details of intake or interstage cooling of main feed air
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    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
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    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
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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
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/12—External refrigeration with liquid vaporising loop
    • 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
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/42—Quasi-closed internal or closed external nitrogen refrigeration cycle
    • 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
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
    • F25J2270/904—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration by liquid or gaseous cryogen in an open loop
    • 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
    • F25J2280/00—Control of the process or apparatus
    • F25J2280/10—Control for or during start-up and cooling down of the installation

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Water Supply & Treatment (AREA)
  • Environmental & Geological Engineering (AREA)
  • Emergency Medicine (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

The invention belongs to the field of natural gas cold energy utilization of liquefied natural gas terminals. The existing liquefied natural gas terminal application is stored in a storage tank (1), heated by an air temperature type vaporizer (2), subjected to pressure regulation, pressure stabilization and metering equipment (3), and then conveyed to terminal gas equipment through an outbound pipeline to be mixed with air for combustion application. The invention relates to a system and a method for preparing oxygen enrichment by utilizing cold energy of terminal liquefied natural gas, which are used for separating air into oxygen enrichment and waste nitrogen, delivering the oxygen enrichment to a natural gas terminal to participate in combustion, and improving the economic benefit of the natural gas terminal; the oxygen enrichment preparation system comprises an air filtering and compressing unit, an air purifying unit, an LNG cold energy recovery unit, a refrigerant circulating unit, an air liquefaction and fractionation unit and a liquid oxygen starting or buffering unit; the method is used for cold recovery of the liquefied natural gas in a new field of terminal application.

Description

System and method for preparing oxygen enrichment by using liquefied natural gas terminal cold energy
Technical Field
The invention belongs to the field of cold energy utilization of liquefied natural gas terminals, and particularly relates to a system for preparing oxygen-enriched air by utilizing cold energy of a liquefied natural gas terminal.
Background
Under the large background of energy conservation and emission reduction, the liquefied natural gas terminal gasification station is widely applied along with the popularization of the liquefied natural gas in industrial production. The liquefied natural gas terminal gasification station is in the gas pipeline uncovered area, solves the main mode of end user's natural gas use demand, is favorable to alleviateing the peak load of gas municipal pipeline, improves end user's gas use emergency guarantee ability, also is the main channel that LNG sales volume increased in recent years. The customs data show that the import of LNG in China in 2018 is 5378 ten thousand tons, and the ratio is increased by 41.2%.
The liquefied natural gas cold energy can be used in the fields of air separation, ice making, light hydrocarbon rectification, carbon dioxide capture, low-temperature cold storage and the like, and the energy consumption in the production process is saved. Because the system is an oxygen enrichment area, the natural gas is a combustible compound, and therefore, cold energy is transferred by adopting a cold medium to utilize the cold energy of the liquefied natural gas, and the direct heat exchange or contact between the natural gas and the rich oxygen is avoided. The oxygen-enriched combustion technology has obvious economic benefit in the application fields of multi-combined natural gas supply, power plants, smelting, glass manufacturing, industrial kiln combustion and the like. The system can obviously reduce the power consumption by utilizing the cold energy released in the gasification process of the liquefied natural gas, is favorable for reducing the preparation cost of rich oxygen and improves the utilization efficiency of the energy applied to the terminal natural gas.
Before entering a gas pipeline of a terminal user, liquefied natural gas needs to be gasified from a cryogenic liquefied state to normal temperature, and a large amount of high-grade cold energy is released in the liquefied natural gas gasification process.
At present, the utilization of liquefied natural gas terminal cold energy to prepare oxygen enrichment is a new application field, and a plurality of patent technologies for preparing high-pressure oxygen enrichment and carrying out air separation by utilizing liquefied natural gas cold energy of a receiving station are published in China.
1. The invention discloses an air separation method for producing high-pressure oxygen-enriched air by utilizing liquefied natural gas cold energy of a receiving station, which is introduced in Chinese invention patent CN 105783424 A.A medium-pressure fractionating tower is additionally arranged on the basis of a conventional double-tower air separation process, raw material air is respectively purified and distributed in high pressure, medium pressure and low pressure, and the system is too complex; in addition, the patent recovers the cold energy of the high-pressure LNG of the liquefied natural gas receiving station, and the liquefied natural gas receiving station is far away from the end user with the requirement of oxygen enrichment, so that the distribution difficulty is high; and the number of receiving stations of the liquefied natural gas is small, the application range of the invention is narrow, and the invention is not suitable for the liquefied natural gas terminal.
2. In the air separation method of the invention patent CN 109140903A, which utilizes the cold energy of liquefied natural gas, in order to fully utilize the cold energy of LNG, on one hand, the cold energy of LNG in the deep cooling part is used for cooling and liquefying nitrogen gas, and cold energy is provided for the air separation process; on the other hand, the system is matched with the receiving station LNG cold quantity change in a liquid nitrogen backflow cold supplementing mode, and the stability of the system for coping with the receiving station LNG cold quantity fluctuation is improved. Because the invention takes sufficient LNG of the receiving station of the liquefied natural gas as the cold source to carry on the air separation, the products are liquid oxygen, liquid nitrogen; the method is not suitable for the requirements of end users for direct combustion application by utilizing liquefied natural gas and oxygen enrichment, and the method is not suitable for liquefied natural gas terminals.
Disclosure of Invention
The invention provides a method for preparing oxygen enrichment by using liquefied natural gas terminal cold energy, which is used for recovering LNG high-grade cold energy; the method comprises the processes of air filtration and compression, air purification, LNG cold energy recovery, refrigerant circulation, air liquefaction and fractionation and liquid oxygen starting/buffering; firstly, compressing and purifying air, cooling by utilizing finished product oxygen enrichment and finished product waste nitrogen, then further cooling by utilizing LNG cold energy through refrigerant throttling and cooling circulation and exchanging heat with air, liquefying the air, fractionating the liquefied air into liquid oxygen enrichment and waste nitrogen gas through a rectifying tower, gasifying the liquid oxygen enrichment and raw material air into oxygen enrichment after exchanging heat, and distributing to a terminal user through a pipeline to participate in natural gas combustion or application.
The invention also provides a system for preparing oxygen enrichment by utilizing the cold energy of the liquefied natural gas terminal, based on the application scene of the terminal user where the liquefied natural gas gasification station is located, the load characteristics and the oxygen enrichment requirement of the terminal user are combed, under the principle that the oxygen enrichment is required, because the output of liquid nitrogen and liquid oxygen products in the traditional air separation process is not available, the cold circulation process is simplified, the cost, the implementation period, the occupied area, the power consumption and the stability of the oxygen enrichment preparation system are more suitable for the application scenes of different types of terminal users, and the application range of the invention is widened. The system is provided with a liquid oxygen buffer tank, and cold supplement is carried out when the natural gas consumption of a terminal user fluctuates so as to keep the refrigeration working condition of the system stable; in addition, the buffer liquid oxygen is used for pre-cooling the system and supplying oxygen to the terminal in the initial stage when the terminal user starts.
The liquefied natural gas terminal comprises application fields of utilizing liquefied natural gas, such as a power plant, metal smelting and heat treatment, glass manufacturing, an industrial kiln, a boiler, ship power, a park gasification station and the like, and application fields of utilizing the liquefied natural gas to carry out multi-combined supply, such as a data center, a hospital, an airport and the like.
The object of the present invention is achieved by the following means
1. Fig. 1 shows the flow relationship between the lng vaporization station and the oxygen-enriched gas production system at the end user:
before the oxygen enrichment preparation system is applied, LNG is stored in the storage tank (1), flows through the air temperature type gasifier (2), is heated to normal temperature, and is conveyed to a terminal to be mixed with air for combustion or application after passing through the pressure regulating metering device (3).
After the oxygen enrichment preparation system is applied, LNG is stored in the storage tank (1), flows through the oxygen enrichment preparation system (4), is heated to normal temperature, is converged into a natural gas system after the air temperature type gasifier (2), and is conveyed to a terminal, air is separated into oxygen enrichment and waste nitrogen through the oxygen enrichment preparation system (4), and the oxygen enrichment is conveyed to the terminal to be mixed with natural gas for combustion or application.
2. Fig. 2 shows a system for producing oxygen-enriched gas by using the terminal cold energy of liquefied natural gas, which is characterized in that: comprises an air filtering and compressing unit, an air purifying unit, an LNG cold energy recovery unit, a refrigerant circulating unit, an air liquefaction and fractionation unit and a liquid oxygen starting/buffering unit.
1) Air filtering and compressing unit
The air filtering and compressing unit comprises a self-cleaning air filter (11), a low-pressure air compressor (12), an ethylene glycol heat exchanger (13), a medium-pressure air compressor (14), a precooling heat exchanger (31) and a pipeline through which the air flows.
Air enters the system from a self-cleaning air filter (11), particulate impurities such as dust and the like contained in the air are removed in the filter, and the air enters a primary filtering air pipe (101); the condensed water is compressed to low pressure by a low-pressure air compressor (12), and is subjected to heat exchange and temperature reduction with a low-temperature glycol solution (404) by a glycol heat exchanger (13), and the condensed water generated in the cooling process is discharged; the gas is compressed to medium pressure by a medium-pressure air compressor (14), enters a compressed air pipe (102), and exchanges heat with the oxygen-enriched gas and the waste nitrogen gas after fractionation through an air precooling heat exchanger (31) to reduce the temperature; enters a pre-cooling compressed air pipe (103).
The cold end and the hot end of the precooling heat exchanger (31) are respectively provided with 3 interfaces, the cold end is respectively connected with a precooling compressed air pipe (103), an oxygen-enriched outlet of the liquefying heat exchanger (32) and a waste nitrogen outlet of the liquefying heat exchanger (32), and the hot end is respectively connected with a compressed air pipe (102), a finished product oxygen-enriched pipe (109) and a finished product waste nitrogen pipe (204)
2) Air purification unit
The air purification unit comprises a molecular sieve (15), a regenerated waste nitrogen pipe (205), a vent silencer (17) and a waste nitrogen discharge pipe (206).
The air is processed into precooled compressed air through the step 1), and the precooled compressed air enters a molecular sieve (15) system through a precooled compressed air pipe (103) to remove water and compounds in the air, becomes low-pressure dry pure compressed air and enters a pure compressed air pipe (104).
For continuous uninterrupted use, the molecular sieve (15) is divided into two parts, which are used alternately, one for purification and one for regeneration. And the finished product sewage nitrogen is shunted and enters a regenerated sewage nitrogen pipe (205) and enters a molecular sieve (15) for regeneration, and the sewage nitrogen enters an emptying silencer (17) through a sewage nitrogen discharge pipe (206) to complete the regeneration of the molecular sieve.
3) LNG cold energy recovery unit
The LNG cold energy recovery unit comprises an LNG control valve (41), an LNG heat exchanger (37), a glycol heat exchanger (42), a glycol heat exchanger (13), a water pump (43) and a pipeline flowing through
When the LNG control valve (41) works, LNG from a liquefied natural gas gasification station enters an LNG heat exchanger (37) through an LNG pipe (401), high-grade cold energy of the LNG is transferred to a refrigerant circulation unit, the LNG is gasified into low-temperature gaseous natural gas in the LNG heat exchanger (37), the low-temperature gaseous natural gas passes through a low-temperature natural gas pipe (402), enters an ethylene glycol heat exchanger (42) and is further heated to normal-temperature natural gas, and then the normal-temperature natural gas pipe (403) outputs the natural gas;
the glycol solution absorbs the cold energy of the natural gas in the glycol heat exchanger (42) for cooling, enters the low-temperature glycol pipe (404) through the water pump (43), then enters the glycol heat exchanger (13) for cooling the compressed air, then returns to the glycol heat exchanger (42) through the glycol pipe (405) to complete circulation, and the low-grade cold energy of the low-temperature natural gas is recovered to cool the air.
4) Refrigerant circulation unit
The refrigerant circulating unit comprises an LNG heat exchanger (37), a compressor (23), a compressor (24), a throttle valve (25), a liquefaction heat exchanger (32) and a pipeline through which the LNG heat exchanger flows.
The gaseous refrigerant is compressed into a medium-pressure refrigerant through the compressor (23), is cooled after LNG cold energy is absorbed by the LNG heat exchanger (37), is further compressed into a high-pressure refrigerant pipe (208) through the compressor (24), is further cooled and liquefied into a low-temperature high-pressure refrigerant through the LNG heat exchanger (37), is throttled, cooled and depressurized through the throttle valve (25), flows through the low-temperature refrigerant pipe (207), exchanges heat with the pure compressed air pipe in the step 2) through the liquefying heat exchanger (32), cools air into a gas-liquid mixture, and flows back to the compressor (23) after absorbing air heat to complete refrigerant circulation.
The cold end and the hot end of the liquefaction heat exchanger (32) are respectively provided with 4 interfaces, the cold end is respectively connected with the low-temperature refrigerant pipe (207), the liquid air pipe (105), the liquid oxygen pipe (108) and the low-temperature polluted nitrogen pipe (202), and the hot end is respectively connected with the inlet of the compressor (23), the pure compressed air pipe (104), the oxygen-enriched inlet of the precooling heat exchanger (31) and the polluted nitrogen inlet of the precooling heat exchanger (31).
5) Air liquefaction fractionation unit
The air liquefaction fractionation unit comprises a precooling heat exchanger (31), a liquefaction heat exchanger (32), a lower tower (33), an upper tower (34), a main condensation evaporator (35), an oxygen-enriched throttling device (16), a liquid nitrogen pressure reducing device (21), a waste nitrogen discharge valve (22) and pipelines flowing through.
Air is processed into pure compressed air through the step 2), the pure compressed air flows into the liquefaction heat exchanger (32) through the pure compressed air pipe (104), the pure compressed air exchanges heat with low-temperature refrigerants, finished product liquid oxygen and low-temperature waste nitrogen, the pure compressed air is cooled and liquefied into liquid gas-liquid mixtures, the liquid gas-liquid mixtures flow into the lower tower (33) system through the liquid air pipe (105) for preliminary separation, medium-pressure liquid oxygen enriched in the bottom of the lower tower (33) flows to the oxygen-enriched throttling device (16) through the liquid oxygen-enriched pipe (106), the liquid oxygen enriched air flows into the middle of the upper tower (34) after being decompressed to participate in upper tower rectification, finished product liquid oxygen is obtained at the bottom of the upper tower (34), the liquid oxygen enriched air flows into the liquefaction heat exchanger (32) through the liquid oxygen pipe (107) to exchange heat with incoming pure compressed air and gasify the incoming material into enriched air, and the enriched air is output from the finished product oxygen-enriched pipe (109) after being further reheated through the precooling heat exchanger (31).
After liquid air is primarily separated in a lower tower (33) system, medium-pressure nitrogen is obtained at the top of the lower tower (33), the medium-pressure nitrogen enters a main condensation evaporator (35) and is condensed into liquid nitrogen by liquid oxygen at the bottom of an upper tower (34), one part of the liquid nitrogen is sent back to the lower tower (33) to maintain the rectification working condition of the lower tower, and the other part of the liquid nitrogen flows to a liquid nitrogen pressure reducing device (21) through a liquid nitrogen pipe (201) to be reduced in pressure and then flows into the top of the upper tower (34) to participate in rectification; the low-pressure waste nitrogen obtained at the top of the upper tower (34) flows into the liquefying heat exchanger (32) through the low-temperature waste nitrogen pipe (202) to exchange heat with incoming pure compressed air and is gasified into waste nitrogen, and the waste nitrogen is further reheated through the precooling heat exchanger (31) and then is output from the finished product waste nitrogen pipe (204); one part of the waste gas is shunted to a regenerated waste nitrogen pipe (205) for regenerating the molecular sieve (15).
Dirty nitrogen discharge valve (22) is system operating mode adjusting device, use the gas when end user high load, when LNG consumption is balanced stable, the system cold volume is sufficient, earlier through some oxygen boosting of liquid oxygen buffer tank storage, if the nitrogen argon volume rises in the finished product oxygen boosting, can open dirty nitrogen discharge valve (22), liquid dirty nitrogen gets into behind low temperature dirty nitrogen pipe (202) reheat from finished product dirty nitrogen pipe (204) through liquid dirty nitrogen pipe (203), because heat transfer area is unchangeable, cold volume emission increases, reduce the discharge temperature of finished product dirty nitrogen gas and take away partly cold volume, it is balanced to reach the rectification operating mode.
6) Liquid oxygen starting/buffering unit
When the terminal user starts, the oxygen enrichment requirement exists, and because the precooling time lag exists in the oxygen enrichment preparation system, the starting requirement is met by adopting the storage liquid oxygen. When the system is started, liquid oxygen is reserved from a liquid oxygen buffer tank (36), flows into a liquefaction heat exchanger (32) through a liquid oxygen pipe (108) to exchange heat and gasify into rich oxygen, is further reheated through a precooling heat exchanger (31), is output from a finished product oxygen enrichment pipe (109) to participate in combustion application, and simultaneously quickly cools the system; the oxygen-enriched preparation system can rapidly enter a stable working condition.
Because the load of the LNG gasification station terminal fluctuates, the signal feedback is obtained by monitoring the natural gas and the oxygen-enriched flow in real time, the system can adjust the waste nitrogen discharge amount and the system air input in real time, and the change of the system working condition still needs certain liquid oxygen buffering to keep the output of the enriched oxygen stable.
The invention is provided with the LNG heat exchanger and the glycol heat exchange cycle, and adopts the cold medium to transfer cold energy for the utilization of the cold energy of the liquefied natural gas, thereby avoiding the direct contact of the natural gas with rich oxygen and air.
The invention is provided with the liquid oxygen buffer tank, and the cold compensation is carried out when the natural gas consumption of the end user fluctuates so as to keep the refrigeration working condition of the system stable; in addition, the buffer liquid oxygen is used for pre-cooling the system and supplying oxygen to the terminal in the initial stage when the terminal user starts.
According to the technical scheme, the refrigeration capacity circulation process is simplified based on the application field scene of the end user where the liquefied natural gas is located, the oxygen enrichment is produced by utilizing the field cold energy for near application, the cost, the implementation period, the occupied area, the power consumption and the stability of the oxygen enrichment preparation system are more suitable for the application scenes of different types of end users, the application range of the refrigeration capacity recovery system is expanded, and the refrigeration capacity recovery system is applied to the liquefied natural gas cold recovery in a new field.
Drawings
FIG. 1 is a flow relationship between an oxygen-enriched gas production system and a liquefied natural gas terminal
A storage tank-1, an air-temperature gasifier-2, a pressure-regulating metering device-3 and an oxygen-enriched preparation system-4.
FIG. 2 is a schematic diagram of the operation of the present invention
A self-cleaning air filter-11, a low-pressure air compressor-12, a glycol heat exchanger-13, a medium-pressure air compressor-14, a molecular sieve-15, an oxygen-enriched throttling device-16, a vent silencer-17, a liquid nitrogen pressure reducing device-21, a waste nitrogen discharge valve-22, a compressor-23, a compressor-24, a throttle valve-25, a precooling heat exchanger-31, a liquefaction heat exchanger-32, a lower tower-33, an upper tower-34, a main condensation evaporator-35, a liquid oxygen buffer tank-36, an LNG heat exchanger-37, an LNG control valve-41, a glycol heat exchanger-42 and a water pump-43;
a primary filter air pipe-101, a compressed air pipe-102, a pre-cooling compressed air pipe-103, a pure compressed air pipe-104, a liquid air pipe-105, a liquid oxygen-rich pipe-106, a liquid oxygen pipe-107, a liquid oxygen pipe-108, a finished product oxygen-rich pipe-109, a liquid nitrogen pipe-201, a low-temperature sewage nitrogen pipe-202, a liquid sewage nitrogen pipe-203, a finished product sewage nitrogen pipe-204, a regenerated sewage nitrogen pipe-205, a sewage nitrogen gas discharge pipe-206, a low-temperature refrigerant pipe-207, a high-pressure refrigerant pipe-208, an LNG pipe-401, a low-temperature natural gas pipe-402, a normal-temperature natural gas pipe-403, a low-temperature ethylene glycol pipe-404 and an ethylene glycol pipe-405.
Detailed Description
The present invention will be described in further detail below with reference to two examples, i.e., a liquefied natural gas terminal of a glass manufacturing plant consuming a certain amount of natural gas of 30 kilo-square/day and a liquefied natural gas terminal of a power plant consuming a certain amount of natural gas of 60 kilo-square/day, in conjunction with the accompanying drawings, but the embodiments of the present invention are not limited thereto, and the present invention is applicable to an application of a liquefied natural gas terminal consuming an amount of natural gas of 1000 kilo-square/day or more. For process parameters not specifically noted, reference may be made to conventional techniques.
Example 1: liquefied natural gas terminal of glass manufacturing plant with natural gas consumption of 30 ten thousand standard squares/day
Fig. 2 shows a system for producing oxygen-enriched air by using the cold energy of the LNG terminal, which includes an air filtering and compressing unit, an air purifying unit, an LNG cold energy recovering unit, a refrigerant circulating unit, an air liquefying and fractionating unit, and a liquid oxygen starting/buffering unit.
The glass manufacturing plant comprises the following process parameters:
the natural gas dosage is as follows: 30 ten thousand standard squares/day, the average flow rate is 3.5 standard squares/second, and the gas pressure is 0.3 MPa;
oxygen enrichment requirement: 72 ten thousand standard square/day, the average flow rate is 8.3 standard square/second, the oxygen-enriched pressure is 0.15MPa, and the oxygen content is more than 90 percent;
the molar composition of the air raw material is as follows: 77.4% of nitrogen, 20.85% of oxygen, 0.92% of argon, 0.03% of CO2 and 0.80% of water;
after the oxygen-enriched preparation system, the discharge amount of waste nitrogen is as follows: 258 million squares/day, and average flow 29.8 squares/second.
1) Air filtering and compressing unit
The air filtering and compressing unit comprises a self-cleaning air filter (11), a low-pressure air compressor (12), an ethylene glycol heat exchanger (13), a medium-pressure air compressor (14), a precooling heat exchanger (31) and a pipeline through which the air flows.
The air flow is 39 square/second, enters the system from a self-cleaning air filter (11), removes particulate impurities such as dust and the like contained in the air in the filter, and enters a primary filtering air pipe (101); the condensed water is compressed to low pressure by a low-pressure air compressor (12), and is subjected to heat exchange and temperature reduction with a low-temperature glycol solution (404) by a glycol heat exchanger (13), and the condensed water generated in the cooling process is discharged; the gas is compressed to medium pressure by a medium-pressure air compressor (14), enters a compressed air pipe (102), and exchanges heat with the oxygen-enriched gas and the waste nitrogen gas after fractionation through an air precooling heat exchanger (31) to reduce the temperature; enters a pre-cooling compressed air pipe (103) and has the flow rate of 38.7 standard squares/second.
The cold end and the hot end of the precooling heat exchanger (31) are respectively provided with 3 interfaces, the cold end is respectively connected with a precooling compressed air pipe (103), an oxygen-enriched outlet of the liquefying heat exchanger (32) and the liquefying heat exchanger (32), and the hot end is respectively connected with a compressed air pipe (102) with the flow rate of 38.7 standard square/second, a finished product oxygen-enriched pipe (109) with the flow rate of 8.3 standard square/second and a finished product sewage nitrogen pipe (204) with the flow rate of a sewage nitrogen outlet of 29.8 standard square/second.
2) Air purification unit
The air purification unit comprises a molecular sieve (15), a regenerated waste nitrogen pipe (205), a vent silencer (17) and a waste nitrogen discharge pipe (206).
The air is processed into precooled compressed air through the step 1), and the precooled compressed air enters a molecular sieve (15) system through a precooled compressed air pipe (103) to remove water and compounds in the air, becomes low-pressure dry pure compressed air and enters a pure compressed air pipe (104).
For continuous uninterrupted use, the molecular sieve (15) is divided into two parts, which are used alternately, one for purification and one for regeneration. And the finished product sewage nitrogen is shunted and enters a regenerated sewage nitrogen pipe (205) and enters a molecular sieve (15) for regeneration, and the sewage nitrogen enters an emptying silencer (17) through a sewage nitrogen discharge pipe (206) to complete the regeneration of the molecular sieve.
3) LNG cold energy recovery unit
The LNG cold energy recovery unit comprises an LNG control valve (41), an LNG heat exchanger (37), a glycol heat exchanger (42), a glycol heat exchanger (13), a water pump (43) and a pipeline flowing through
When the LNG control valve (41) works, LNG from a liquefied natural gas gasification station enters an LNG heat exchanger (37) through an LNG pipe (401), high-grade cold energy of the LNG is transferred to a refrigerant circulation unit, the LNG is gasified into low-temperature gaseous natural gas in the LNG heat exchanger (37), the low-temperature gaseous natural gas passes through a low-temperature natural gas pipe (402), enters an ethylene glycol heat exchanger (42) and is further heated to normal-temperature natural gas, the flow rate is 3.5 standard square/second, and the normal-temperature natural gas pipe (403) outputs the natural gas;
the ethylene glycol solution absorbs cold energy of natural gas in the ethylene glycol heat exchanger (42) for cooling, enters the low-temperature ethylene glycol pipe (404) through the water pump (43), then enters the ethylene glycol heat exchanger (13) for cooling compressed air, then returns to the ethylene glycol heat exchanger (42) through the ethylene glycol pipe (405) to complete circulation, low-grade cold energy of the low-temperature natural gas is recycled to cool air, and air flow is 39 standard square/second.
4) Refrigerant circulation unit
And selecting nitrogen as a circulating refrigerant, wherein the refrigerant circulating unit comprises an LNG heat exchanger (37), a compressor (23), a compressor (24), a throttle valve (25), a liquefaction heat exchanger (32) and a pipeline through which the LNG heat exchanger flows.
The nitrogen is compressed into medium-pressure nitrogen through a compressor (23), is cooled after LNG cold energy is absorbed by an LNG heat exchanger (37), is further compressed into a high-pressure nitrogen pipe (208) through a compressor (24), is further cooled into liquid nitrogen through the LNG heat exchanger (37), is throttled, cooled and depressurized through a throttle valve (25), flows through a low-temperature nitrogen pipe (207), exchanges heat with the pure compressed air pipe in the step 2) through a liquefaction heat exchanger (32), cools the air into a gas-liquid mixture, and flows back to the compressor (23) after the nitrogen absorbs air heat to complete refrigerant circulation.
The cold end and the hot end of the liquefaction heat exchanger (32) are respectively provided with 4 interfaces, the cold end is respectively connected with the low-temperature nitrogen pipe (207), the liquid air pipe (105), the liquid oxygen pipe (108) and the low-temperature nitrogen pipe (202), the hot end is respectively connected with the inlet of the compressor (23), the flow of the pure compressed air pipe (104) is 38.3 standard square/second, the flow of the oxygen-enriched inlet of the precooling heat exchanger (31) is 8.3 standard square/second, and the flow of the nitrogen-contaminated inlet of the precooling heat exchanger (31) is 29.8 standard square/second.
5) Air liquefaction fractionation unit
The air liquefaction fractionation unit comprises a precooling heat exchanger (31), a liquefaction heat exchanger (32), a lower tower (33), an upper tower (34), a main condensation evaporator (35), an oxygen-enriched throttling device (16), a liquid nitrogen pressure reducing device (21), a waste nitrogen discharge valve (22) and pipelines flowing through.
Air is processed into pure compressed air through the step 2), the pure compressed air flows into the liquefaction heat exchanger (32) through the pure compressed air pipe (104), the pure compressed air exchanges heat with low-temperature refrigerants, finished product liquid oxygen and low-temperature dirty nitrogen, the pure compressed air is cooled and liquefied into liquid gas-liquid mixtures, the liquid gas-liquid mixtures flow into the lower tower (33) system through the liquid air pipe (105) for primary separation, medium-pressure liquid oxygen enriched in the bottom of the lower tower (33) flows to the oxygen-enriched throttling device (16) through the liquid oxygen-enriched pipe (106), the liquid oxygen enriched air flows into the middle of the upper tower (34) after being decompressed to participate in upper tower rectification, finished product liquid oxygen is obtained at the bottom of the upper tower (34), the liquid oxygen enriched air flows into the liquefaction heat exchanger (32) through the liquid oxygen pipe (107) to exchange heat and gasify with incoming pure compressed air into enriched oxygen, and 8.3 standard/second enriched oxygen is output from the finished product oxygen-enriched pipe (109) after being further reheated through the precooling heat exchanger (31).
After liquid air is primarily separated in a lower tower (33) system, medium-pressure nitrogen is obtained at the top of the lower tower (33), the medium-pressure nitrogen enters a main condensation evaporator (35) and is condensed into liquid nitrogen by liquid oxygen at the bottom of an upper tower (34), one part of the liquid nitrogen is sent back to the lower tower (33) to maintain the rectification working condition of the lower tower, and the other part of the liquid nitrogen flows to a liquid nitrogen pressure reducing device (21) through a liquid nitrogen pipe (201) to be reduced in pressure and then flows into the top of the upper tower (34) to participate in rectification; low-pressure waste nitrogen obtained at the top of the upper tower (34) flows into the liquefying heat exchanger (32) through the low-temperature waste nitrogen pipe (202) to exchange heat with incoming pure compressed air and is gasified into waste nitrogen, and 29.8 standard/second waste nitrogen is output from the finished product waste nitrogen pipe (204) after being further reheated by the precooling heat exchanger (31); one part of the waste gas is shunted to a regenerated waste nitrogen pipe (205) for regenerating the molecular sieve (15).
Dirty nitrogen discharge valve (22) is system operating mode adjusting device, use the gas when glass manufacturing factory high load, when the LNG consumption is balanced stable, the system cold volume is sufficient, can store partly oxygen boosting through liquid oxygen buffer unit, if nitrogen-containing argon volume rises in the finished product oxygen boosting, dirty nitrogen discharge valve (22) can be opened, liquid dirty nitrogen gets into behind low temperature dirty nitrogen pipe (202) reheat from finished product dirty nitrogen pipe (204) through liquid dirty nitrogen pipe (203), because heat transfer area is unchangeable, cold volume emission increases, reduce the discharge temperature of finished product dirty nitrogen gas and take away partly cold volume, it is balanced to reach the rectification operating mode.
6) Liquid oxygen starting/buffering unit
When a production line of a glass manufacturing plant starts a furnace, oxygen enrichment is required, and since a precooling time lag exists in an oxygen enrichment preparation system, liquid oxygen is stored to meet the furnace starting requirement. When the system is started, liquid oxygen is reserved from a liquid oxygen buffer tank (36), flows into a liquefaction heat exchanger (32) through a liquid oxygen pipe (108) to exchange heat and gasify into rich oxygen, is further reheated through a precooling heat exchanger (31), is output from a finished product oxygen enrichment pipe (109) to participate in combustion application, and simultaneously quickly cools the system; the oxygen-enriched preparation system can rapidly enter a stable working condition. When the glass manufacturing plant produces, the oxygen-rich flow rate is 8.3 standard square/second, the stable work is started according to the 10 minutes of the system, and the liquid oxygen-rich gasification rate is calculated according to the 720 volume ratio. The effective volume V of the oxygen-enriched buffer tank is 600 multiplied by 8.3/720 is 6.9 cubic meters; for this purpose, a liquid oxygen buffer tank of 8 cubes is used.
Because the load of the LNG gasification station terminal fluctuates, the system can adjust the discharge amount of the waste nitrogen and the air input amount of the system in real time by monitoring the feedback of terminal signals such as natural gas and oxygen-enriched flow in real time, but the change of the working condition of the system still needs certain liquid oxygen buffering to keep the output stability of the enriched oxygen.
Example 2: the liquefied natural gas terminal of a power plant with a certain natural gas consumption of 60 kilo-square/day comprises the following process parameters:
the natural gas dosage is as follows: 60 ten thousand standard squares/day, the average flow rate is 7.0 standard squares/second, and the gas pressure is 0.3 MPa;
oxygen enrichment requirement: 144 ten thousand standard square/day, the average flow is 16.6 standard square/second, the oxygen-enriched pressure is 0.15MPa, and the oxygen content is more than 90 percent;
the molar composition of the air raw material is as follows: 77.4% of nitrogen, 20.85% of oxygen, 0.92% of argon, 0.03% of CO2 and 0.80% of water;
after the oxygen-enriched preparation system, the discharge amount of waste nitrogen is as follows: 516 million square/day, average flow 59.8 square/second.
Two 72-ten-thousand-square/day oxygen-enriched preparation systems which are the same as those in the real-time example 1 are selected and used in parallel, the liquid oxygen starting/buffering units are integrated and shared, and a 15-cubic liquid oxygen buffer tank is selected. The single machine operation mode is the same as that of the example 1, and the combined operation is different in that: when the power plant is in a low-load working condition, starting 1 set of oxygen enrichment preparation system, and keeping the other set for standby; when the power plant is in a high-load state, the buffer oxygen enrichment meets the starting requirement of the 2 nd set of oxygen enrichment preparation system, and stable oxygen enrichment output is kept.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the above embodiments, which are only illustrative, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be equivalents thereof, which may be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims (8)

1. A method for preparing oxygen-enriched air by utilizing liquefied natural gas terminal cold energy is characterized by comprising the following steps: the method comprises the processes of air filtration and compression, air purification, LNG cold energy recovery, refrigerant circulation, air liquefaction and fractionation, and liquid oxygen starting or buffering; firstly, air is compressed and purified, finished product oxygen enrichment and finished product waste nitrogen are utilized for cooling, then LNG cold energy is utilized to be subjected to refrigerant throttling and cooling circulation, the air is further cooled and is liquefied through heat exchange with the air, the liquefied air is fractionated into liquid oxygen enrichment and waste nitrogen through a rectifying tower, the liquid oxygen enrichment is gasified into oxygen enrichment after heat exchange with raw material air, and the oxygen enrichment is distributed to a terminal user through a pipeline to participate in natural gas combustion or application.
2. The invention relates to a system for preparing oxygen-enriched air by utilizing liquefied natural gas terminal cold energy, which is characterized in that: the system comprises an air filtering and compressing unit, an air purifying unit, an LNG cold energy recovery unit, a refrigerant circulating unit, an air liquefaction and fractionation unit and a liquid oxygen starting/buffering unit;
a) the air filtering and compressing unit is characterized by comprising a self-cleaning air filter (11), a low-pressure air compressor (12), an ethylene glycol heat exchanger (13), a medium-pressure air compressor (14), a precooling heat exchanger (31) and a pipeline through which the air flows; air is cleaned of particulate matters such as dust and the like contained in the air through a self-cleaning air filter (11), the air is compressed through a low-pressure air compressor (12), is subjected to heat exchange and cooling through an ethylene glycol heat exchanger (13), is compressed to medium pressure through a medium-pressure air compressor (14), and is subjected to heat exchange and cooling with fractionated oxygen-enriched gas and contaminated nitrogen gas through an air precooling heat exchanger (31);
the cold end and the hot end of the precooling heat exchanger (31) are respectively provided with 3 connectors, the cold end is respectively connected with a precooling compressed air pipe (103), an oxygen-enriched outlet of the liquefying heat exchanger (32) and a waste nitrogen outlet of the liquefying heat exchanger (32), and the hot end is respectively connected with a compressed air pipe (102), a finished product oxygen-enriched pipe (109) and a finished product waste nitrogen pipe (204);
b) the air purification unit is characterized by comprising a molecular sieve (15), a regenerated waste nitrogen pipe (205), a vent silencer (17) and a waste nitrogen discharge pipe (206);
air enters a molecular sieve (15) system through a precooling compressed air pipe (103) to remove water and compounds in the air, becomes low-pressure dry pure compressed air and enters a pure compressed air pipe (104); for continuous uninterrupted use, the molecular sieve (15) is divided into two parts which are used alternately, one for purification and one for regeneration; the finished product sewage nitrogen is shunted and enters a regenerated sewage nitrogen pipe (205) and enters a molecular sieve (15) for regeneration, and the sewage nitrogen enters an emptying silencer (17) through a sewage nitrogen discharge pipe (206) to complete the regeneration of the molecular sieve;
c) the LNG cold energy recovery unit is characterized by comprising an LNG control valve (41), an LNG heat exchanger (37), a glycol heat exchanger (42), a glycol heat exchanger (13), a water pump (43) and a pipeline through which the water flows;
when the LNG control valve (41) works, LNG from a liquefied natural gas gasification station enters an LNG heat exchanger (37) through an LNG pipe (401), high-grade cold energy of the LNG is transferred to a refrigerant circulation unit, the LNG is gasified into low-temperature gaseous natural gas in the LNG heat exchanger (37), the low-temperature gaseous natural gas passes through a low-temperature natural gas pipe (402), enters an ethylene glycol heat exchanger (42) and is further heated to normal-temperature natural gas, and then the normal-temperature natural gas pipe (403) outputs the natural gas;
the ethylene glycol solution absorbs the cold energy of the natural gas in the ethylene glycol heat exchanger (42) for cooling, enters the low-temperature ethylene glycol pipe (404) through the water pump (43), then enters the ethylene glycol heat exchanger (13) for cooling the compressed air, then returns to the ethylene glycol heat exchanger (42) through the ethylene glycol pipe (405) to complete circulation, and recovers the low-grade cold energy of the low-temperature natural gas to cool the air;
d) the refrigerant circulating unit is characterized by comprising an LNG heat exchanger (37), a compressor (23), a compressor (24), a throttle valve (25), a liquefaction heat exchanger (32) and a pipeline through which the LNG heat exchanger flows;
in application scenes of different scales, the compressor (23) and the throttle valve (25) can be replaced by the expansion machine, and the expansion machine is favorable for improving the utilization efficiency of cold energy and reducing the energy consumption, but occupies a large area; wherein the compressor (23) is replaced by the compression end of the expander, and the throttle valve (25) is replaced by the expansion end of the expanding agent;
the gaseous refrigerant is compressed into a medium-pressure refrigerant through a compressor (23), is cooled after LNG cold energy is absorbed by an LNG heat exchanger (37), further compresses the refrigerant through a compressor (24) and enters a high-pressure refrigerant pipe (208), is further cooled and liquefied into a low-temperature high-pressure refrigerant through the LNG heat exchanger (37), is throttled, cooled and depressurized through a throttle valve (25), flows through a low-temperature refrigerant pipe (207), exchanges heat with the pure compressed air pipe in the step 2) through a liquefying heat exchanger (32), cools air into a gas-liquid mixture, and flows back to the compressor (23) after absorbing air heat to complete refrigerant circulation;
the cold end and the hot end of the liquefaction heat exchanger (32) are respectively provided with 4 interfaces, the cold end is respectively connected with the low-temperature refrigerant pipe (207), the liquid air pipe (105), the liquid oxygen pipe (108) and the low-temperature waste nitrogen pipe (202), and the hot end is respectively connected with the inlet of the compressor (23), the pure compressed air pipe (104), the oxygen-enriched inlet of the precooling heat exchanger (31) and the waste nitrogen inlet of the precooling heat exchanger (31);
e) the air liquefaction fractionation unit is characterized by comprising a precooling heat exchanger (31), a liquefaction heat exchanger (32), a lower tower (33), an upper tower (34), a main condensation evaporator (35), an oxygen-enriched throttling device (16), a liquid nitrogen pressure reducing device (21), a waste nitrogen discharge valve (22) and pipelines flowing through;
air flows into a liquefying heat exchanger (32) through a pure compressed air pipe (104), the pure compressed air exchanges heat with a low-temperature refrigerant, finished product liquid oxygen and low-temperature waste nitrogen in the liquefying heat exchanger (32), is cooled and liquefied into a liquid gas-liquid mixture, flows into a lower tower (33) system through a liquid air pipe (105) for preliminary separation, medium-pressure liquid oxygen enriched at the bottom of the lower tower (33) flows to an oxygen-enriched throttling device (16) through a liquid oxygen-enriched pipe (106), flows into the middle part of an upper tower (34) after being decompressed to participate in upper tower rectification, obtains finished product liquid oxygen at the bottom of the upper tower (34), flows into the liquefying heat exchanger (32) through a liquid oxygen pipe (107) to exchange heat with incoming pure compressed air and gasify the incoming material into enriched oxygen, and is output from a finished product oxygen-enriched pipe (109) after being further reheated through a precooling heat exchanger (31);
after liquid air is primarily separated in a lower tower (33) system, medium-pressure nitrogen is obtained at the top of the lower tower (33), the medium-pressure nitrogen enters a main condensation evaporator (35) and is condensed into liquid nitrogen by liquid oxygen at the bottom of an upper tower (34), one part of the liquid nitrogen is sent back to the lower tower (33) to maintain the rectification working condition of the lower tower, and the other part of the liquid nitrogen flows to a liquid nitrogen pressure reducing device (21) through a liquid nitrogen pipe (201) to be reduced in pressure and then flows into the top of the upper tower (34) to participate in rectification; the low-pressure waste nitrogen obtained at the top of the upper tower (34) flows into the liquefying heat exchanger (32) through the low-temperature waste nitrogen pipe (202) to exchange heat with incoming pure compressed air and is gasified into waste nitrogen, and the waste nitrogen is further reheated through the precooling heat exchanger (31) and then is output from the finished product waste nitrogen pipe (204); one part of the waste gas is shunted to a regenerated waste nitrogen pipe (205) for regenerating the molecular sieve (15);
the waste nitrogen discharge valve (22) is a system working condition adjusting device, when high-load gas is used by a terminal user, the system cold quantity is sufficient, a part of oxygen enrichment is stored through the liquid oxygen buffer tank firstly, if the nitrogen and argon content in the finished product oxygen enrichment rises, the waste nitrogen discharge valve (22) can be opened, liquid waste nitrogen enters the low-temperature waste nitrogen pipe (202) through the liquid waste nitrogen pipe (203) for reheating and then flows out of the finished product waste nitrogen pipe (204), the discharge temperature of the finished product waste nitrogen is reduced, and a part of cold quantity is taken away, so that the balance of the rectification working condition is achieved;
f) the liquid oxygen starting or buffering unit is characterized in that: the system is provided with a liquid oxygen buffer tank, wherein cold supplement is carried out when the natural gas consumption of a terminal user fluctuates, and in addition, buffer liquid oxygen is used for system precooling and terminal oxygen enrichment initial supply when the terminal user starts; when a terminal user starts, the oxygen enrichment requirement exists, and because the precooling time lag exists in the oxygen enrichment preparation system, the liquid oxygen is stored to meet the starting requirement; when the system is started, liquid oxygen is reserved from a liquid oxygen buffer tank (36), flows into a liquefaction heat exchanger (32) through a liquid oxygen pipe (108) to exchange heat and gasify into rich oxygen, is further reheated through a precooling heat exchanger (31), is output from a finished product oxygen enrichment pipe (109) to participate in combustion application, and simultaneously quickly cools the system; the oxygen-enriched preparation system can rapidly enter a stable working condition.
3. The invention is characterized in that: set up the liquid oxygen buffer tank in order to keep oxygen boosting output stable and satisfy the terminal and start the oxygen boosting demand, because LNG vaporizing station terminal load can fluctuate to some extent, through signal feedback such as real-time supervision natural gas, oxygen-enriched flow pressure, dirty nitrogen emission and system air input can be adjusted in real time to the system, and system operating mode changes still needs the liquid oxygen buffering.
4. The invention is characterized in that: the LNG heat exchanger and the ethylene glycol heat exchange cycle are arranged, cold energy is transferred by using cold medium to the cold energy of the liquefied natural gas, and the direct heat exchange or contact of the natural gas with rich oxygen and air is avoided.
5. The invention is characterized in that: based on the application scene of the end user where the liquefied natural gas is located, the refrigeration capacity circulation flow is simplified, and the on-site cold energy is utilized to produce the near application of the oxygen enrichment, so that the cost, the implementation period, the occupied area, the power consumption and the stability of the oxygen enrichment preparation system are more suitable for the application scenes of different types of end users, and the application range of the invention is widened; and for terminal application occasions with surplus cold energy, liquid oxygen and liquid nitrogen output interfaces can be added.
6. The invention is characterized in that: the method is suitable for the liquefied natural gas terminal application occasions with the gas consumption of 1000 square/day or more at the liquefied natural gas terminal.
7. The invention is characterized in that: the lng end users include, but are not limited to, power plants, metal smelting and heat treatment, glass manufacturing, industrial kilns, boilers, ship power, and gasification stations in a park, and data centers, hospitals, airports, and the like, which use lng for multiple co-generation.
8. The present invention is not limited to the above-described embodiments, but is intended to cover modifications, changes, substitutions, combinations, simplifications, and equivalents, which may be made without departing from the spirit and scope of the invention.
CN202010050238.0A 2020-01-17 2020-01-17 System and method for preparing oxygen enrichment by using liquefied natural gas terminal cold energy Pending CN113137828A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111174529A (en) * 2020-03-05 2020-05-19 赖家俊 System and method for removing hydrocarbon and carbon by using cold energy of liquefied natural gas
CN113797700A (en) * 2021-09-22 2021-12-17 乔治洛德方法研究和开发液化空气有限公司 Integrated unit and method for separating air and producing carbon dioxide-rich product

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111174529A (en) * 2020-03-05 2020-05-19 赖家俊 System and method for removing hydrocarbon and carbon by using cold energy of liquefied natural gas
CN113797700A (en) * 2021-09-22 2021-12-17 乔治洛德方法研究和开发液化空气有限公司 Integrated unit and method for separating air and producing carbon dioxide-rich product

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