CN219492359U - LNG cold energy utilization system with cold energy air separation and cold energy power generation coupled - Google Patents

LNG cold energy utilization system with cold energy air separation and cold energy power generation coupled Download PDF

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Publication number
CN219492359U
CN219492359U CN202320107292.3U CN202320107292U CN219492359U CN 219492359 U CN219492359 U CN 219492359U CN 202320107292 U CN202320107292 U CN 202320107292U CN 219492359 U CN219492359 U CN 219492359U
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cold energy
compressor
nitrogen
power generation
air separation
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任美凤
韩一松
沈今阳
田国栋
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Hang Yang Group Co ltd
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Hang Yang Group Co ltd
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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
    • F25J3/04109—Arrangements of compressors and /or their drivers
    • F25J3/04115—Arrangements of compressors and /or their drivers characterised by the type of prime driver, e.g. hot gas expander
    • 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
    • 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
    • F25J3/0403—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 nitrogen
    • 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
    • F25J3/04109—Arrangements of compressors and /or their drivers
    • F25J3/04115—Arrangements of compressors and /or their drivers characterised by the type of prime driver, e.g. hot gas expander
    • F25J3/04133—Electrical motor as the prime mechanical driver
    • 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
    • F25J3/04109—Arrangements of compressors and /or their drivers
    • F25J3/04139—Combination of different types of drivers mechanically coupled to the same compressor, possibly split on multiple compressor casings
    • 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
    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
    • F25J3/04187—Cooling of the purified feed air by recuperative heat-exchange; Heat-exchange with product streams
    • F25J3/04218—Parallel arrangement of the main heat exchange line in cores having different functions, e.g. in low pressure and high pressure cores
    • F25J3/04224—Cores associated with a liquefaction or 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
    • 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
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04254—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using the cold stored in external cryogenic fluids
    • F25J3/0426—The cryogenic component does not participate in the fractionation
    • F25J3/04266—The cryogenic component does not participate in the fractionation and being liquefied hydrocarbons
    • 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
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04333—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04351—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen
    • 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
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/20—Integrated compressor and process expander; Gear box arrangement; Multiple compressors on a common shaft

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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)

Abstract

The utility model provides a LNG cold energy utilization system of cold energy air separation and cold energy electricity generation coupling, including air separation system, nitrogen liquefaction system and rankine cycle power generation system, air compressor and low pressure nitrogen compressor are supporting respectively outside the air separation system, this low pressure nitrogen compressor is connected with nitrogen liquefaction system, the external supporting circulation nitrogen compressor that has of nitrogen liquefaction system is used for pressurizing pressure nitrogen, this air compressor, low pressure nitrogen compressor, circulation nitrogen compressor is connected with rankine cycle power generation system, through the coaxial integration of each compressor of rankine cycle expander and cold energy air separation system, and arrange the motor according to the energy matching condition as required when the system is running, can further reduce the electric energy consumption of air separation system, reduce unnecessary energy conversion loss simultaneously, retrieve the cold energy more effectively, realize energy saving and consumption reduction, the purpose of raise the efficiency, and is rational in infrastructure, the practicality is strong, advantages such as flexibility.

Description

LNG cold energy utilization system with cold energy air separation and cold energy power generation coupled
Technical Field
The utility model relates to the technical field of LNG cold energy utilization, in particular to an LNG cold energy utilization system with cold energy air separation and cold energy power generation coupled.
Background
In order to realize energy conservation and carbon reduction, the new high energy consumption project is required to meet the related energy conservation and consumption reduction requirements. The air separation equipment is used for producing oxygen, nitrogen, argon and other gas and liquid products in the fields of metallurgy, chemical industry, machinery and the like, and the air is required to be filtered, pressurized, precooled, decontaminated and cooled to an ultralow temperature environment, and the components are separated by utilizing the difference of boiling points of the components in the liquefied air, wherein the separation temperature is between-196 ℃ and-150 ℃. The conventional air separation equipment adopts expansion refrigeration to obtain an ultralow-temperature environment, and the refrigeration capacity is completely generated by an electric driving machine and needs to consume a large amount of electric power, so that the product unit power consumption of the conventional air separation equipment is very high, and the air separation equipment belongs to high-energy-consumption equipment.
Natural Gas (NG) is a widely used green energy source, and is converted into Liquefied Natural Gas (LNG) through a low temperature process when transported in the ocean, and the storage temperature is typically-162 ℃. When the LNG is used, the LNG is gasified to normal temperature, a large amount of cold energy is released in the process, the cold energy of the LNG is absorbed by taking seawater as a heat source, and the cold seawater is discharged into the sea again, so that huge waste of the cold energy of the LNG and environmental pollution can be caused. And if the cold energy is utilized, huge economic benefits can be generated.
The air separation temperature zone is close to the LNG storage temperature, so that the high-grade low-temperature cold energy of LNG can be fully utilized, and the energy consumption of the air separation equipment is greatly reduced. The prior mature LNG cold energy space division technology is a liquefied circulating nitrogen technology by utilizing LNG cold energy: after nitrogen extracted from the air separation system is cooled to a certain temperature through a nitrogen liquefaction system, the nitrogen enters a circulating nitrogen compressor for pressurization, and then returns to the nitrogen liquefaction system to exchange heat with low-temperature LNG continuously, the nitrogen is liquefied, a liquid nitrogen product is output, and the rest liquid nitrogen is conveyed to air separation equipment to obtain low-temperature liquid oxygen and liquid argon. After the LNG is cooled by the nitrogen, residual cooling can be provided for the glycol aqueous solution, and after the glycol aqueous solution is cooled, the glycol aqueous solution can replace interstage circulating cooling water of the air compressor and is used for cooling between the air compressors, so that the interstage gas temperature of the air compressor is reduced, and the power of the air compressor is reduced. The LNG cold energy air separation omits a refrigeration expander, reduces the inlet air temperature of an air compressor and a circulating nitrogen compressor, and can reduce the total energy consumption by about 50 percent. However, after the cold energy air separation technology is adopted, the energy consumption of the whole set of air separation equipment still belongs to high energy consumption equipment, so that further measures of energy conservation and consumption reduction are needed.
The LNG cold energy power generation technology is to partially convert cold energy released during LNG gasification into electric energy, and is another utilization mode of LNG cold energy. At present, single-stage low-temperature Rankine cycle is widely adopted in each cold energy power generation method for power generation, hydrocarbon substances are used as an intermediate medium, seawater is used as a heat source, cold energy is obtained from LNG, pressure is provided by a pump, working medium outputs work through an expander under the action of temperature difference and pressure difference, and kinetic energy is converted into electric energy by a generator. However, there are multiple functional conversion losses, firstly, the mechanical work converted into electric energy by cold energy generation generates losses, and then the electric power is transmitted to other equipment to be converted into mechanical work by a motor, and a series of losses are generated. Therefore, the utility model provides an LNG cold energy utilization system with cold energy air separation and cold energy power generation coupled.
Disclosure of Invention
In order to solve the problems of overhigh power consumption and LNG cold energy waste of an air separation system, the utility model provides an LNG cold energy utilization system with cold energy air separation and cold energy power generation coupled, on the basis that a great amount of electric energy is saved by applying an LNG cold energy air separation technology, the LNG cold energy power generation technology is used for further reducing the electric energy consumption of equipment such as an air compressor, a circulating nitrogen compressor, a low-pressure nitrogen compressor and the like, and meanwhile, the energy loss of electric energy and mechanical energy conversion is reduced in a mode of coaxially integrating the compressor and an expander, so that the more effective utilization of LNG cold energy is realized.
The utility model adopts the following technical scheme:
the utility model provides a cold energy air separation and LNG cold energy utilization system of cold energy electricity generation coupling, includes air separation system, nitrogen gas liquefaction system and rankine cycle power generation system, air separation system is external to be supporting respectively to have air compressor and low pressure nitrogen gas compressor, and this low pressure nitrogen gas compressor is connected with nitrogen gas liquefaction system, gets into in the nitrogen gas liquefaction system after merging the nitrogen gas after the pressurization of low pressure nitrogen gas compressor, the external supporting circulation nitrogen gas compressor that has of nitrogen gas liquefaction system, this air compressor, low pressure nitrogen gas compressor, circulation nitrogen gas compressor are connected with at least one rankine cycle power generation system.
As preferable: the system comprises a plurality of Rankine cycle power generation systems, wherein the Rankine cycle power generation systems are respectively connected with an air compressor, a low-pressure nitrogen compressor and a circulating nitrogen compressor, each Rankine cycle power generation system is provided with a working medium circulating pump, a seawater gasifier, an expander and an LNG heat exchanger which are connected through pipelines, wherein low-temperature low-pressure liquid working medium enters the circulating pump for pressurization and then enters a cold fluid runner of the seawater gasifier, seawater flowing in a hot runner is heated into high-temperature high-pressure saturated gas and enters the expander ET, the high-temperature high-pressure saturated gas is expanded into low-temperature low-pressure gas and mechanical work is output to the outside, the low-temperature low-pressure saturated gas enters the hot fluid runner of the LNG heat exchanger, LNG flowing in the cold fluid runner is condensed into liquid, and finally the LNG working medium enters the working medium circulating pump to complete one cycle.
As preferable: and one or more compressors of the air compressor, the low-pressure nitrogen compressor and the circulating nitrogen compressor can be selected to be respectively connected with an expander of the Rankine cycle power generation system according to actual production requirements so as to replace the traditional motor drive, and the compressors matched with the air separation system can be an air compressor and a low-pressure nitrogen compressor or only an air compressor.
As preferable: the air compressor, the low-pressure nitrogen compressor and the circulating nitrogen compressor are respectively connected with the expander into a horizontal structure and are integrated in a connecting shaft mode, wherein the expander does work to drive the air compressor, the low-pressure nitrogen compressor and the circulating nitrogen compressor to operate, and a clutch is arranged on the connecting shaft and used for disconnecting the expander from the compressor when a certain system stops operating.
As preferable: when the working capacity of the expander is not matched with the power required by the air compressor, the low-pressure nitrogen compressor and the circulating nitrogen compressor, additional motors are respectively arranged, and the motors are connected with an external power grid and can be used for taking electricity from the power grid or transmitting electric energy to the power grid.
As preferable: the circulating working medium in the Rankine cycle power generation system can be a single working medium or a mixed working medium.
According to the cold energy air separation and cold energy power generation coupling method, through coaxial integration of the Rankine cycle expander and each compressor of the cold energy air separation system and arrangement of the motors according to energy matching conditions of the Rankine cycle expander and the compressors when the system is in operation, the electric energy consumption of the air separation system can be further reduced, unnecessary energy conversion loss is reduced, LNG cold energy is effectively recovered, the purposes of saving energy, reducing consumption and improving efficiency are achieved, and the method has the advantages of being reasonable in structure, strong in practicability, high in flexibility and the like.
Drawings
Fig. 1 is a schematic diagram of a method of coupling a cold energy air separation system and an LNG cold energy power generation system according to the present utility model.
Fig. 2 is a schematic diagram of several different connection modes of the expander, the compressor and the motor.
Detailed Description
The utility model will be described in detail below with reference to the attached drawings: as shown in fig. 1, the cold energy utilization system with coupled air separation and cold energy power generation comprises an air separation system a, a nitrogen liquefaction system b, a rankine cycle power generation system c, a rankine cycle power generation system d and a rankine cycle power generation system e;
the Rankine cycle power generation system c comprises a working medium circulating pump P1, a seawater gasifier H1, an expander ET1 and an LNG heat exchanger E1 which are connected through pipelines. The low-temperature low-pressure liquid working medium enters a circulating pump P1 for pressurization, then enters a cold fluid flow channel of a seawater gasifier H1, is heated into high-temperature high-pressure saturated gas by seawater flowing in the hot fluid flow channel, enters an expander ET1 for expansion into low-temperature low-pressure gas and outputting mechanical work to the outside, then enters an LNG heat exchanger E1 hot fluid flow channel, is condensed into liquid by LNG flowing in the cold fluid flow channel, and finally enters a working medium circulating pump P1 for completing a cycle.
The Rankine cycle power generation system d comprises a working medium circulating pump P2, a seawater gasifier H2, an expander ET2 and an LNG heat exchanger E2 which are connected through pipelines. The low-temperature low-pressure liquid working medium enters a circulating pump P2 for pressurization, then enters a cold fluid flow channel of a seawater gasifier H2, is heated into high-temperature high-pressure saturated gas by seawater flowing in the hot fluid flow channel, enters an expander ET2, expands into low-temperature low-pressure gas and outputs mechanical work to the outside, then enters an LNG heat exchanger E2 hot fluid flow channel, is condensed into liquid by LNG flowing in the cold fluid flow channel, and finally enters a working medium circulating pump P2 to complete one cycle.
The Rankine cycle power generation system E comprises a working medium circulating pump P3, a seawater gasifier H3, an expander ET3 and an LNG heat exchanger E3 which are connected through pipelines. The low-temperature low-pressure liquid working medium enters a circulating pump P3 for pressurization, then enters a cold fluid flow channel of a seawater gasifier H3, is heated into high-temperature high-pressure saturated gas by seawater flowing in the hot fluid flow channel, enters an expander ET3, expands into low-temperature low-pressure gas and outputs mechanical work to the outside, then enters an LNG heat exchanger E3 hot fluid flow channel, is condensed into liquid by LNG flowing in the cold fluid flow channel, and finally enters a working medium circulating pump P3 to complete one cycle.
The air separation system a is matched with an air compressor C1 and a low-pressure nitrogen compressor C2. The filtered air is pressurized by an air compressor C1 and then sent to other devices for next operation, and finally products such as oxygen, nitrogen, argon and the like are obtained through separation. The low-pressure nitrogen compressor C2 is used for compressing low-pressure nitrogen pumped out from the top of the air separation system and is used as a raw material for supplementing liquid nitrogen products.
The nitrogen liquefaction system b is used for providing LNG cold energy for high-pressure nitrogen so as to produce liquid nitrogen and providing liquid nitrogen for the air separation system, and is matched with a circulating nitrogen compressor C3. The pressure nitrogen is pumped out of the air separation system a, is converged with the nitrogen pressurized by the low-pressure nitrogen compressor C2, enters the nitrogen liquefaction system b, absorbs LNG cold energy to become low-temperature nitrogen, is compressed by the circulating nitrogen compressor C3, and finally becomes liquid nitrogen to be used as a cold source to return to the air separation system a or be sent out as a product. LNG enters the nitrogen liquefaction system b, the cold energy is transferred to circulating nitrogen, and the circulating nitrogen is heated and then is discharged out of the nitrogen liquefaction system b.
Further, the circulating working media in the rankine cycle power generation system c, the rankine cycle power generation system d and the rankine cycle power generation system e can be a single working medium or a mixed working medium.
Further, according to engineering practice, one or more compressors of the air compressor C1, the low-pressure nitrogen compressor C2 and the circulating nitrogen compressor C3 can be selected to be respectively connected with an expander of the Rankine cycle power generation system to replace a traditional motor to acquire kinetic energy. The compressors matched with the air separation system can be an air compressor C1 and a low-pressure nitrogen compressor C2 or only the air compressor C1. For example, only the air compressor C1 is selected to be connected with the rankine cycle power generation system C to obtain power, and the low-pressure nitrogen compressor C2 and the circulating nitrogen compressor C3 are still driven by a traditional motor in various manners.
As shown in fig. 2, the connection between the air compressor C1 of the air separation system a and the rankine cycle power generation system C is taken as an example, and the connection between the expander and the compressor is shown. The compressor C1 and the expander ET1 are of a horizontal structure, are integrated in a coaxial mode, and work of the expander ET1 drives the compressor C1 to operate; the connecting shaft is provided with a clutch ACLH1 (connection modes 1-3 in fig. 2) or a clutch ACLH1 (connection modes 1-3 in fig. 2) and a clutch BCLH2 (connection mode 4 in fig. 2) which are used for disconnecting the expander ET1 from the compressor C1 when a certain system stops running. According to the matching condition of the acting capacity of the expansion machine ET1 and the power required by the compressor C1 when the system operates, the motors M1, M2 and M3 are arranged according to the requirement and are connected with an external power grid, and the power can be taken from the power grid or the power can be transmitted to the power grid. When the output power of the expander ET1 exceeds the power required by the compressor C1, a motor M1 is arranged at the side of the expander ET1 and connected with the expander ET1; when the output power of the expander ET1 does not meet the power required by the compressor C1, a motor M2 is arranged at the side of the compressor C1 and is connected with the compressor C1; when the system is running, the motor M1 can be arranged at the side of the expander ET1 to be connected with the expander ET1 and the motor M2 can be arranged at the side of the compressor C1 to be connected with the compressor C1, or the motor M3 can be arranged on the connecting shaft of the compressor C1 and the expander ET1 to be connected with the compressor C1 and the expander ET1.
Alternatively, if the demand for liquid nitrogen product is not high, it is not necessary to withdraw low pressure nitrogen from the upper column of air separation system a to replenish the liquid nitrogen and omit low pressure nitrogen compressor C2.
It is specifically noted that: the cold energy power generation method coupled with cold energy space division is not limited to the single-stage Rankine cycle power generation method, and all the modified forms of Rankine cycle and other methods for performing expansion power generation by utilizing LNG cold energy belong to the protection scope of the utility model.
The implementation case parameters are as follows:
an air separation system a with the production scale liquid yield of 600 tons/day is to be built, the hour power consumption is 17000kWh, the year power consumption is 13600 kWh, and the year power consumption is converted into standard coal 16714 tons. The LNG cold energy air separation technology is adopted, namely a nitrogen liquefaction system b is added, the LNG cold energy is used for creating a low-temperature environment from the air separation system a through circulating nitrogen, the power consumption of the whole equipment per hour can be reduced to 8000kWh, the annual power consumption is 6400 kWh, the standard coal 7865.6 tons is converted, and the higher standard coal consumption is still achieved. On the basis, a set of Rankine cycle cold energy power generation device C with the LNG design flow of 200 tons/hour and rated power of 3500kWh is added, the air compressor C1 is driven to operate, the power consumption of the whole equipment is 4500kWh in hours, the annual power consumption is 3600 kWh, the standard coal 4424 tons is converted, and the consumed standard coal amount is greatly reduced. Through the coupling Rankine cycle cold energy power generation device c, compared with the technology of only adopting cold energy space division, the annual energy saving 2800 kilokWh is realized, the standard coal 3440 tons is converted, the carbon emission is reduced by 9254 tons, the requirements of national energy conservation, carbon reduction and development of circular economy are met, and the energy-saving and carbon reduction combined type solar energy power generation device has obvious economic and environmental benefits.
Through the real implementation case, on the basis that LNG cold energy provides cold energy for the air separation system, the expander of the LNG cold energy Rankine cycle power generation system is utilized to directly drive the compressor of the air separation system to operate, so that the electric energy consumption of the air separation system is further reduced, a series of unnecessary losses such as energy conversion loss are reduced, and the cold energy utilization efficiency is truly improved.
The above embodiments are merely preferred examples for clearly illustrating the present utility model, but the embodiments of the present utility model are not limited to the above examples. Therefore, all equivalent changes and modifications made in accordance with the present utility model fall within the scope of the present utility model.

Claims (5)

1. The utility model provides a cold energy air separation and cold energy electricity generation coupled LNG cold energy utilization system, includes air separation system (a), nitrogen liquefaction system (b) and rankine cycle power generation system, its characterized in that: the air separation system (a) is externally matched with an air compressor (C1) and a low-pressure nitrogen compressor (C2), the low-pressure nitrogen compressor (C2) is connected with the nitrogen liquefaction system (b), nitrogen generated by the air separation system (a) is pressurized by the low-pressure nitrogen compressor (C2) and then is converged with pressure nitrogen to enter the nitrogen liquefaction system (b), the nitrogen liquefaction system (b) is externally matched with a circulating nitrogen compressor (C3) for pressurizing the pressure nitrogen, and the air compressor (C1), the low-pressure nitrogen compressor (C2) and the circulating nitrogen compressor (C3) are connected with at least one Rankine cycle power generation system.
2. The LNG cold energy utilization system of cold energy air separation and cold energy power generation coupling of claim 1, wherein: the system comprises a Rankine cycle power generation system, wherein the Rankine cycle power generation system is divided into 3 units, the three units are respectively connected with an air compressor (C1), a low-pressure nitrogen compressor (C2) and a circulating nitrogen compressor (C3), each Rankine cycle power generation system is provided with a working medium circulating pump (P), a seawater gasifier (H), an Expander (ET) and an LNG heat exchanger (E), the Rankine cycle power generation system, the two units are connected through pipelines, a low-temperature low-pressure liquid working medium enters the circulating pump (P) for pressurization, then enters the cold fluid runner of the seawater gasifier (H), is heated into high-temperature high-pressure saturated gas by the seawater flowing in the hot fluid runner and enters the Expander (ET), expands into low-temperature low-pressure gas and outputs mechanical work to the outside, then enters the hot fluid runner of the LNG heat exchanger (E), the LNG flowing in the cold fluid runner is condensed into liquid, and finally enters the working medium circulating pump (P) to complete one cycle.
3. The LNG cold energy utilization system coupled with cold energy air separation and cold energy power generation according to claim 2, wherein: the air compressor (C1), the low-pressure nitrogen compressor (C2), the circulating nitrogen compressor (C3) and the Expander (ET) are of a horizontal structure and are integrated in a connecting shaft mode, wherein the expander ET does work to drive the air compressor (C1), the low-pressure nitrogen compressor (C2) and the circulating nitrogen compressor (C3) to operate, and a clutch A (CLH 1) or a clutch A (CLH 1) and a clutch B (CLH 2) are arranged on the connecting shaft and are used for disconnecting the expander (ET 1) from the compressor (C1) when a certain system stops operating.
4. The LNG cold energy utilization system of cold energy air separation and cold energy power generation coupling according to claim 3, wherein: when the working capacity of the Expander (ET) is not matched with the power required by the air compressor (C1), the low-pressure nitrogen compressor (C2) and the circulating nitrogen compressor (C3), an additional motor is also arranged, and the motor is connected with an external power grid and can take electricity from the power grid or transmit electric energy to the power grid.
5. The LNG cold energy utilization system coupled with cold energy air separation and cold energy power generation according to claim 2, wherein: the circulating working medium in the Rankine cycle power generation system can be a single working medium or a mixed working medium.
CN202320107292.3U 2023-02-03 2023-02-03 LNG cold energy utilization system with cold energy air separation and cold energy power generation coupled Active CN219492359U (en)

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