CN108072235B - Air separation system - Google Patents

Air separation system Download PDF

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Publication number
CN108072235B
CN108072235B CN201611022494.9A CN201611022494A CN108072235B CN 108072235 B CN108072235 B CN 108072235B CN 201611022494 A CN201611022494 A CN 201611022494A CN 108072235 B CN108072235 B CN 108072235B
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China
Prior art keywords
pipeline
air separation
output end
separation plant
heat exchanger
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CN201611022494.9A
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CN108072235A (en
Inventor
钱立新
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JIANGSU SUZHOU STEEL GROUP CO Ltd
New Founder Holdings Development Co ltd
Suzhou Suxin Special Steel Co ltd
Original Assignee
JIANGSU STEEL GROUP CO Ltd JIANGSU
SUZHOU SUXIN SPECIAL STEEL CO Ltd
Peking University Founder 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
    • F25J3/04406—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 using a dual pressure main column system
    • F25J3/04412—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 using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
    • 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
    • F25J3/04151—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
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/0429—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of feed air, e.g. used as waste or product air or expanded into an auxiliary column
    • F25J3/04303—Lachmann expansion, i.e. expanded into oxygen producing or low pressure column
    • 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
    • F25J3/04357—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 and comprising a gas work expansion 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
    • 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
    • F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
    • F25J3/04393—Details relating to the work expansion, e.g. process parameter etc. using multiple or multistage gas work expansion
    • 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
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04793—Rectification, e.g. columns; Reboiler-condenser
    • 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
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04812—Different modes, i.e. "runs" of operation
    • F25J3/04818—Start-up of the process
    • 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
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
    • F25J3/04951—Arrangements of multiple air fractionation units or multiple equipments fulfilling the same process step, e.g. multiple trains in a network
    • F25J3/04957—Arrangements of multiple air fractionation units or multiple equipments fulfilling the same process step, e.g. multiple trains in a network and inter-connecting equipments upstream of the fractionation unit (s), i.e. at the "front-end"
    • 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
    • F25J2230/24—Multiple compressors or compressor stages in parallel
    • 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
    • F25J2230/40—Processes or apparatus involving steps for increasing the pressure of gaseous process streams the fluid being 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
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • F25J2240/04—Multiple expansion turbines in parallel
    • 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
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/40—Processes or apparatus involving steps for recycling of process streams the recycled stream being air

Abstract

The invention provides an air separation system, comprising: the air separation equipment comprises a raw material processing device, a heat exchange device and a return pipeline, wherein the output end of the return pipeline is connected with the cold medium input end of the heat exchange device through a first pipeline and a second pipeline, one end of the first pipeline is communicated with the output end of the raw material processing device, and a first control unit is arranged on the first pipeline 3; one end of the second pipeline is communicated with the backflow pipeline, and a second control unit is arranged on the second pipeline; the input end and the output end of the cooling device are respectively communicated with the other end of the first pipeline and the other end of the second pipeline; when the air separation plant is started, the first control unit controls the first pipeline to be conducted, and the second control unit controls the second pipeline to be conducted. The invention utilizes the cooling device of the liquefying device to assist the starting of the air separation plant, thereby greatly shortening the starting time of the air separation plant, further obviously reducing the energy consumption of industries such as metallurgy and the like and realizing the purpose of energy conservation.

Description

Air separation system
Technical Field
The invention relates to the technical field of air separation, in particular to an air separation system.
Background
Air separation equipment is an energy-consuming large household in industries such as metallurgy, and the air separation equipment needs to complete a starting process before normal production. The starting process of the air separation equipment comprises three stages of cooling equipment, liquid accumulation and purity regulation, wherein the cooling equipment and the liquid accumulation in the three stages need a large amount of cold energy to complete, and particularly the required cold storage amount is larger by adopting the conventional flow of full-rectification argon preparation by using structured packing.
In the prior art, the cold energy in the starting process of the air separation plant generally comes from a turboexpander of the air separation plant, but the turboexpander of the air separation plant is matched with the supplementary cold loss in normal operation, so the refrigerating capacity is limited, and the starting time of the air separation plant is very long. In the process of starting the air separation plant, main high-power equipment such as a raw material air compressor and the like continuously run, but the main condensation evaporator does not work at the stage, so a large amount of processed air is diffused, and only a small amount of processed air enters the turboexpander for refrigeration, so that the energy consumption at the starting stage is very high, and only the energy consumption is realized, and no product is produced.
Disclosure of Invention
In order to solve at least one of the above technical problems, an object of the present invention is to provide an air separation system.
The invention provides an air separation system, comprising: the air separation equipment comprises a raw material processing device, a heat exchange device and a return pipeline, wherein the raw material processing device can output dry and clean air, and the output end of the return pipeline is connected with the cold medium input end of the heat exchange device; one end of the first pipeline is communicated with the output end of the raw material processing device, and a first control unit for controlling the on-off of the first pipeline is arranged on the first pipeline; one end of the second pipeline is communicated with the backflow pipeline, and a second control unit for controlling the on-off of the second pipeline is arranged on the second pipeline; the input end of the cooling device is communicated with the other end of the first pipeline, and the output end of the cooling device is communicated with the other end of the second pipeline; when the air separation plant is started, the first control unit controls the first pipeline to be conducted, and the second control unit controls the second pipeline to be conducted.
The air separation system provided by the invention utilizes the cooling device of the liquefying device to assist in refrigeration, and the refrigerating capacity of the cooling device is very large because the liquefying device needs to produce liquid, so that the starting time of the air separation device can be greatly shortened, the energy consumption of industries such as metallurgy and the like is further remarkably reduced, and the purpose of saving energy is realized; meanwhile, the air-cooled type air separation plant is different from a normal liquefaction device which utilizes an air source of a circulating compressor to refrigerate, but utilizes air diffused by a raw material processing device of the air separation plant to refrigerate, so that the utilization rate of the air processed by the raw material processing device is improved, the energy consumption of the liquefaction device during refrigeration is also saved, and the energy is also greatly saved.
In addition, since gas users of metallurgical enterprises are in discontinuous use, but the matched air separation plants are in continuous production, in order to reduce the waste of the gas product, the related enterprises are generally equipped with a separate liquefying device to liquefy and store the surplus gas product. Before the air separation plant is normally started, the liquefaction plant is often shut down because no acceptable gas product has been produced, just to make use of it to assist in refrigeration. Therefore, the technical scheme can achieve the purpose of shortening the starting time of the air separation plant only by slightly modifying the existing air separation plant and the liquefying device, thereby generating considerable energy-saving effect, being convenient for popularization and having very good application prospect.
Specifically, when the air separation plant starts, the raw material processing device can process raw material air into dry and clean air to be output, wherein a part of air enters the cooling device of the liquefying device through the first pipeline, is cooled into low-temperature fluid in the cooling device and then is conveyed to the backflow pipeline of the air separation plant through the second pipeline, and enters the heat exchange device of the air separation plant through the backflow pipeline, so that cold energy is contributed in the heat exchange device to be used in the starting stage of the air separation plant. When the liquid level of the main condensation evaporator of the air separation plant is close to the working height, namely the air separation plant is basically started, the first pipeline and the second pipeline are cut off, and meanwhile, the cooling device of the liquefying device is closed, so that the air separation plant can normally work.
It is worth to be noted that, the liquefaction device generally includes a medium input pipeline, a circulation compressor, a cooling device, a circulation backflow pipeline and a liquid storage device, the cooling device includes a pressure-increasing expansion machine and a heat exchanger, the medium input pipeline is connected with an input end of the circulation compressor and one end of the circulation backflow pipeline, an output end of the circulation compressor is connected with an input end of a pressure-increasing portion of the pressure-increasing expansion machine, an output end of the pressure-increasing portion is connected with a heat medium input end of the heat exchanger and an input end of an expansion portion of the pressure-increasing expansion machine, an output end of the expansion portion is connected with a cold medium input end of the heat exchanger, a heat medium output end of the heat exchanger is connected with the other end of the circulation. The corresponding working principle is as follows: the fluid medium enters a liquefying device through a medium input pipeline, then enters a circulating compressor to be primarily compressed in the circulating compressor, then enters a pressurizing part of a pressurizing expansion machine to be secondarily compressed, and then enters a heat exchanger; the fluid medium entering the heat exchanger is divided into two paths, one path of fluid medium enters an expansion part of the booster expander after being preliminarily cooled to carry out deep refrigeration, and returns to the heat exchanger after the deep refrigeration, and exchanges heat with the other path of fluid medium in the heat exchanger, so that the other path of fluid medium can be fully exchanged and cooled in the heat exchanger to be changed into liquid which is output from a cold medium output end of the heat exchanger, and the fluid medium which is output from a hot medium output end of the heat exchanger after the heat exchange returns to an input end of the circulating compressor through a circulating reflux pipeline, and enters the circulating compressor after being converged with the fluid medium input by a medium input pipeline to; and the liquid output from the cold medium output end of the heat exchanger enters the liquid storage device for storage.
Therefore, when the liquefaction device is normally used, the air source of the circulating compressor is utilized for refrigeration, and the energy consumption of the circulating compressor during operation is very large; when the liquefaction device is used for assisting the air separation plant to start, the liquefaction device utilizes the air processed by the raw material processing device of the air separation plant to refrigerate, and the raw material processing device is in a running state when the air separation plant is started, so that part of the processed air is supplied to the liquefaction device, the utilization rate of the air processed by the liquefaction device is improved, the running of a high-power circulating compressor of the liquefaction device is avoided, and the energy is greatly saved.
It will be appreciated that an air separation plant generally comprises a feedstock treatment unit, a refrigeration unit, a heat exchange unit, a rectification column, a return conduit and a media outlet conduit: the output end of the raw material processing device is connected with the hot medium input end of the heat exchange device and the input end of the refrigerating device, the cold medium output end of the heat exchange device is connected with the lower tower of the rectifying tower, the output end of the refrigerating device is connected with the upper tower of the rectifying tower, the input end of the backflow pipeline is connected with the medium output end of the rectifying tower, the output end of the backflow pipeline is connected with the cold medium input end of the heat exchange device, and the hot medium output end of the heat exchange device is connected with the medium output pipeline. The corresponding working principle is as follows: the dry clean air output by the raw material processing device is divided into two paths, one path of the dry clean air enters the heat exchange device, exchanges heat with the low-temperature medium input into the heat exchange device through the backflow pipeline, is cooled and then enters the lower tower of the rectifying tower; the other path enters a refrigerating device, and enters an upper tower of the rectifying tower after deep refrigeration and temperature reduction in the refrigerating device; the upper tower and the lower tower are matched to separate air into various fluid media, such as low-temperature nitrogen, low-temperature oxygen, low-temperature waste nitrogen and the like, and the fluid media are output from the medium output end of the upper tower; the output low-temperature fluid medium enters a return pipeline, then flows to the heat exchange device, exchanges heat with air in the heat exchange device and is output to a medium output pipeline through a heat medium output end.
Therefore, the essence of the present application is: the output end of a raw material output device of the air separation plant is connected with a dry air pipeline to a cooling device of a liquefying device, and meanwhile, the output end of the cooling device of the liquefying device is connected with a low-temperature fluid pipeline to a backflow pipeline of the air separation plant, so that not only is the refrigerating device (generally a turboexpander) of the air separation plant provide cold for the starting stage of the air separation plant, but also the cooling device of the liquefying device is included, and the refrigerating capacity of the cooling device of the liquefying device is far greater than that of the refrigerating device of the air separation plant, so that the decisive influence is exerted on the starting time of the air separation plant, the starting time of the air separation plant is greatly shortened, the energy consumption is remarkably saved, great influence can be generated on industries such as metallurgy, and a new era of industries such as metallurgy is developed.
In addition, the air separation system in the above embodiment provided by the present invention may further have the following additional technical features:
in the above technical solution, the first control unit includes a first cut-off valve; the second control unit includes a second shutoff valve.
The first stop valve is arranged on the first pipeline, the second stop valve is arranged on the second pipeline, the on-off of the first pipeline and the second pipeline can be effectively controlled through the on-off of the first stop valve and the second stop valve, the structure is simple, and the control is reliable. Specifically, when the air separation plant is started, the first stop valve and the second stop valve are opened, and the cooling device of the liquefaction device is started, so that the air separation plant can be started by the aid of the liquefaction device; and when the air separation plant is basically started, closing the first stop valve and the second stop valve, and closing the cooling device of the liquefying device, so that the air separation plant and the liquefying device can be normally produced according to respective production procedures.
In any one of the above technical solutions, the first control unit further includes a third stop valve and a first release valve, the third stop valve is disposed adjacent to the first stop valve, and the first release valve is located between the first stop valve and the third stop valve.
The first control unit further comprises a third stop valve and a first emptying valve, namely two stop valves and one emptying valve are arranged on the first pipeline, so that the first pipeline can be reliably cut off after the air separation plant is started, and the pollution of the leakage air of the first pipeline to fluid media in the liquefying device is avoided during normal work. Specifically, when the air separation plant is started, a first stop valve and a second stop valve are opened, and a first emptying valve is closed to realize the conduction of a first pipeline; when the air separation plant finishes starting, close first stop valve and second stop valve, open first atmospheric valve to whether the first pipeline of inspection leaks, be convenient for in time take measures.
It is worth mentioning that, because the two ends of the second pipeline are high-purity fluid media flowing during normal operation, the risk of pollution is low, and only one stop valve needs to be arranged.
In any of the above technical solutions, the exterior of the first pipeline and the exterior of the second pipeline are wrapped with thermal insulation materials.
In any of the above technical solutions, the heat insulating material wrapped outside the first pipeline is a mineral wool material; the heat insulation material wrapped outside the second pipeline is a polyurethane foam material.
The heat insulation materials are wrapped outside the first pipeline and the second pipeline, so that the cold loss of fluid media in the first pipeline and the second pipeline can be reduced, the utilization rate of cold is improved, and the starting time of the air separation equipment is further shortened. The first pipeline is wrapped with mineral wool materials with general heat preservation performance, and is not limited to the mineral wool materials certainly, because the air output by the raw material processing device flows in the first pipeline, and the air is only subjected to preliminary precooling by the cooling tower, so that the temperature is not particularly low, and the heat preservation can be carried out by using the common mineral wool materials; and the air which is deeply refrigerated by the cooling device flows in the second pipeline, the temperature of the air is lower, and the air is conveyed to the air separation equipment for starting the air separation equipment, so that a polyurethane foaming material with relatively good heat insulation performance needs to be adopted, and the cold loss can be effectively reduced by adopting other heat insulation materials with relatively good heat insulation performance.
It is worth to say that, because the first pipeline is completely positioned outside the cold box, the whole pipeline is required to be wrapped with a heat-insulating material; the second pipeline may be partially located in the cold box and partially located outside the cold box, and the temperature in the cold box is very low, so that the heat-insulating material is only required to be wrapped on the part located outside the cold box.
In any one of the above technical solutions, the cooling device includes a booster expander and a heat exchanger, the booster expander includes a booster portion and an expansion portion, an input end of the booster portion is communicated with an input end of the cooling device, an output end of the booster portion is communicated with a heat medium input end of the heat exchanger and an input end of the expansion portion, an output end of the expansion portion is communicated with a cold medium input end of the heat exchanger, and a cold medium output end of the heat exchanger is communicated with an output end of the cooling device; when the air separation plant is started, the heat medium output end of the heat exchanger is communicated with the outside and used for diffusing the fluid medium output from the heat medium output end of the heat exchanger.
In any of the above technical solutions, a circulation return line is provided between a medium input line of the liquefaction device and a heat medium output end of the heat exchanger; fluid media output by a heat medium output end of the heat exchanger sequentially flow through the circulating return pipeline and the medium input pipeline and then are discharged; or, a fourth stop valve close to the medium input pipeline is arranged on the circulating reflux pipeline, a third pipeline close to the heat medium output end of the heat exchanger is connected to the circulating reflux pipeline, a second emptying valve is arranged on the third pipeline, and fluid medium output by the heat medium output end of the heat exchanger is discharged through the third pipeline.
As before, when the liquefaction device is in normal operation, the air source enters the input end of the cooling device, specifically the pressurizing part of the pressurizing expansion machine, from the circulating compressor; the liquid medium after being cooled and liquefied is output to a liquid storage device from the output end of the cooling device, specifically, the liquid medium is output from the cold medium output end of the heat exchanger; in the working process of the cooling device, the low-temperature gas output by the expansion part of the booster expander is a refrigerant source in the heat exchanger, namely the expansion part needs to convey the low-temperature gas to the heat exchanger, and the low-temperature gas is output from the heat medium output end of the heat exchanger after heat exchange and temperature rise in the heat exchanger and circularly flows back to the circulating compressor. However, when the liquefaction device assists the air separation plant to start, the circulating compressor does not work, so that the gas output by the heat medium output end of the heat exchanger needs to be dispersed to ensure the normal operation of the cooling device. As for the specific diffusion manner, there may be, but not limited to, the following two cases:
because the circulation return pipeline is connected with the medium input pipeline of the liquefaction device, and the medium input pipeline can be communicated with the outside necessarily, the gas output by the heat medium output end of the heat exchanger can be directly diffused into the external environment through the circulation return pipeline and the medium input pipeline, so that the improvement of the existing device is smaller and the implementation is easier; or
The medium return pipeline is connected with a third pipeline with a second emptying valve, gas output by a heat medium output end of the heat exchanger is released to the external environment through the third pipeline, meanwhile, in order to ensure the normal operation of the liquefying device, a fourth stop valve is required to be arranged on the circulating return pipeline and is positioned between the medium input pipeline and the third pipeline, when the air separation equipment is started, the fourth stop valve is closed, the second emptying valve is opened, and when the air separation equipment is started, the fourth stop valve is opened, the second emptying valve is closed, so that the aims of the invention can be achieved, and the protection scope of the invention is also included.
In any of the above embodiments, the liquefaction unit is a single expansion liquefaction unit with a freezer; or, the liquefaction device is a high-low pressure two-stage expansion liquefaction device, the cooling device of the high-low pressure two-stage expansion liquefaction device comprises two booster expanders which are respectively a low-pressure stage booster expander and a high-pressure stage booster expander, and when the air separation plant is started, only the low-pressure stage booster expander is started.
The liquefaction device is a single expansion liquefaction device with a refrigerating machine, namely, the cooling device only comprises one additional expansion machine, but the refrigerating machine is also connected between the booster expansion machine and the heat exchanger, and the refrigerating machine can further improve the cooling capacity conveyed to the air separation plant by the cooling device, so that the starting time of the air separation plant is further shortened.
The liquefaction device is a high-pressure and low-pressure two-stage expansion liquefaction device, namely the cooling device comprises two booster expanders, the medium pressure output by one booster expander is relatively low and is a low-pressure stage booster expander, the medium pressure output by the other booster expander is relatively high and is a high-pressure stage booster expander, and the low-pressure stage expander is only used for assisting the starting of the air separation plant because most of metallurgical air separation plants are full low-pressure processes, so that only the gas pressure output by the low-pressure stage expander is matched with the air separation plant.
Naturally, the variety of the liquefaction plant is various, and is not limited to the two cases, and they are not listed here, but those skilled in the art should understand that as long as the cooling device of the liquefaction plant is used to assist the air separation plant in cooling, it is in accordance with the design idea and spirit of the present application, and thus all should be within the protection scope of the present application.
In any of the above technical solutions, the raw material processing apparatus includes a raw material air compressor and a molecular sieve adsorber, an input end of the molecular sieve adsorber is connected to an output end of the raw material air compressor, and an output end of the molecular sieve adsorber is communicated with an output end of the raw material processing apparatus.
The raw material processing device comprises a raw material air compressor and a molecular sieve adsorber, the raw material air compressor can compress raw material air into air with certain pressure, the molecular sieve adsorber can remove components harmful to the air separation equipment and the liquefaction device, such as water vapor, carbon dioxide, acetylene, propylene, propane, nitrous oxide and the like in the compressed air, and the obtained dry and clean air is used by the air separation equipment and the liquefaction device so as to ensure the normal operation of the air separation equipment and the liquefaction device.
In any one of the above technical solutions, the backflow pipeline includes a nitrogen backflow pipe, an oxygen backflow pipe and a waste nitrogen backflow pipe, and one end of the second pipeline is connected to the nitrogen backflow pipe.
One end of the second pipeline is connected to the nitrogen return pipe, because the input end of the nitrogen return pipe is positioned at the uppermost part of the upper tower relative to other return pipes and is discharged out of the cold box through the safety valve pipeline above the upper tower, the second pipeline can be directly connected to the pipe of the safety valve pipeline discharged out of the cold box for the unit of the existing air separation equipment and liquefaction device, thereby being convenient for implementation and saving investment; as for the other end of the second pipeline, the cold box of the liquefaction device is very small, and the direct sand raking transformation can be carried out. Of course, for newly-built units of the air separation plant and the liquefaction device, the pipeline can be directly arranged in the cold box by using the method, the cold box of the air separation plant and the cold box of the liquefaction device are preferably made on the same concrete foundation, and even the liquefaction device is embedded into the cold box of the air separation plant, so that the pipeline can be designed in a targeted optimization manner. And for the first pipeline, the first pipeline is easy to reform because the first pipeline is outside the cold box.
Of course, it should be understood by those skilled in the art that since the air separation plant is started, the fluid medium flowing through is air, and there is no product output and collection, one end of the second pipeline may also be connected to the oxygen return pipe or the waste nitrogen return pipe, or when the return pipe further includes return pipes for other media, such as argon return pipe, etc., these return pipes may also be connected to the pipelines of the heat exchange devices, so long as the matching of pressure levels is considered and measures for preventing product contamination during operation are taken, the effect of shortening the start-up time of the air separation plant can be achieved, and the basic principles are the same, which are not listed one by one here, but all fall within the protection scope of the present invention.
In any of the above technical solutions, the air separation plant is an air separation plant of an external compression process.
Compared with the air separation plant in the internal compression process, the air separation plant in the external compression process does not need to produce liquid, the cooling capacity of the configured turbine expansion machine is relatively smaller, and the starting time is longer only by supplementing the cold loss in normal production, so that the starting is assisted by using the liquefying device, and the energy-saving significance is more remarkable. Certainly, the air separation plant in the internal compression process can also utilize the liquefaction device to assist the start-up of the air separation plant, and can also achieve the purpose of shortening the start-up time and saving energy consumption.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic configuration diagram of an air separation plant according to an embodiment of the present invention;
FIG. 2 is a schematic structural view of a liquefaction apparatus according to an embodiment of the present invention.
Wherein, the correspondence between the reference numbers and the component names in fig. 1 and fig. 2 is:
1 air separation plant, 10 raw material air compressors, 20 molecular sieve adsorbers, 30 turboexpanders, 40 heat exchange devices, 50 subcoolers, 61 lower towers, 62 main condensing evaporators, 63 upper towers, 71 nitrogen return pipes, 72 oxygen return pipes, 73 waste nitrogen return pipes, 81 nitrogen output pipes, 82 oxygen output pipes, 83 waste nitrogen output pipes, 2 liquefaction devices, 210 circulating compressors, 211 fifth stop valves, 220 booster expanders, 221 pressurization parts, 222 expansion parts, 230 refrigerators, 240 heat exchangers, 250 liquid storage devices, 260 circulating return pipes, 261 fourth stop valves, 270 medium input pipes, 3 first pipes, 310 first stop valves, 320 third stop valves, 330 first emptying valves, 4 second pipes, 410 second stop valves, 5 third pipes and 510 second emptying valves.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.
An air separation system according to some embodiments of the present invention is described below with reference to fig. 1 and 2.
As shown in fig. 1 and fig. 2, the air separation system provided by the present invention includes: an air separation plant 1, a first conduit 3, a second conduit 4 and a liquefaction plant 2.
Specifically, the air separation plant 1 comprises a raw material processing device, a heat exchange device 40 and a return pipeline, wherein the raw material processing device can output dry and clean air, and the output end of the return pipeline is connected with the cold medium input end of the heat exchange device 40; one end of the first pipeline 3 is communicated with the output end of the raw material processing device, and a first control unit for controlling the on-off of the first pipeline 3 is arranged on the first pipeline 3; one end of the second pipeline 4 is communicated with the backflow pipeline, and a second control unit for controlling the on-off of the second pipeline 4 is arranged on the second pipeline 4; the liquefaction device 2 comprises a cooling device, the input end of the cooling device is communicated with the other end of the first pipeline 3, and the output end of the cooling device is communicated with the other end of the second pipeline 4; when the air separation plant 1 is started, the first control unit controls the first pipeline 3 to be conducted, and the second control unit controls the second pipeline 4 to be conducted.
The air separation system provided by the invention utilizes the cooling device of the liquefying device 2 to assist in refrigeration, and the liquefying device 2 needs to produce liquid, so that the refrigerating capacity of the cooling device is very large, the starting time of the air separation plant 1 can be greatly shortened, the energy consumption of industries such as metallurgy and the like is further remarkably reduced, and the purpose of saving energy is realized; meanwhile, the air source of the circulating compressor 210 is used for refrigeration of the normal liquefaction device 2, but the air released by the raw material processing device of the air separation plant 1 is used for refrigeration, so that the utilization rate of the air processed by the raw material processing device is improved, the energy consumption of the liquefaction device 2 during refrigeration is also saved, and the energy is also greatly saved.
In addition, since the gas users of the metallurgical enterprises are in discontinuous use, but the air separation plant 1 is continuously produced, in order to reduce the waste of the gas product, the related enterprises are generally equipped with a separate liquefaction device 2 to liquefy and store the surplus gas product. Before the air separation plant 1 is normally started up, the liquefaction plant 2 is often also shut down, just to use it to assist in refrigeration, since no acceptable gas product has been produced. Therefore, the technical scheme can achieve the purpose of shortening the starting time of the air separation plant 1 only by slightly modifying the existing air separation plant 1 and the liquefying device 2, thereby generating considerable energy-saving effect, being convenient for popularization and having very good application prospect.
More specifically, as shown in fig. 2, the cooling device includes a booster expander 220 and a heat exchanger 240, the booster expander 220 includes a booster part 221 and an expansion part 222, an input end of the booster part 221 is communicated with an input end of the cooling device, an output end of the booster part 221 is communicated with a heat medium input end of the heat exchanger 240 and an input end of the expansion part 222, an output end of the expansion part 222 is communicated with a cold medium input end of the heat exchanger 240, and a cold medium output end of the heat exchanger 240 is communicated with an output end of the cooling device; when the air separation plant 1 is started, the heat medium output end of the heat exchanger 240 is communicated with the outside, and is used for discharging the fluid medium output from the heat medium output end of the heat exchanger 240.
Further, as shown in fig. 2, a circulation return pipe 260 is provided between the medium input pipe 270 of the liquefaction device 2 and the heat medium output end of the heat exchanger 240; the fluid medium output from the heat medium output end of the heat exchanger 240 flows through the circulation return pipeline 260 and the medium input pipeline 270 in sequence and is discharged; or, a fourth stop valve 261 close to the medium input pipeline 270 is arranged on the circulation return pipeline 260, a third pipeline 5 close to the heat medium output end of the heat exchanger 240 is connected to the circulation return pipeline 260, a second vent valve 510 is arranged on the third pipeline 5, and the fluid medium output by the heat medium output end of the heat exchanger 240 is discharged through the third pipeline 5.
When the liquefaction device 2 normally operates, an air source enters the input end of the cooling device from the circulating compressor 210, specifically, enters the pressurization part 221 of the pressurization expander 220; the liquid medium after temperature reduction and liquefaction is output to the liquid storage device 250 from the output end of the cooling device, specifically, is output from the cold medium output end of the heat exchanger 240; in the operation process of the cooling device, the low-temperature gas output by the expansion part 222 of the booster expander 220 is a source of the refrigerant in the heat exchanger 240, that is, the expansion part 222 must deliver the low-temperature gas to the heat exchanger 240, and the low-temperature gas is output from the heat medium output end of the heat exchanger 240 after being subjected to heat exchange and temperature rise in the heat exchanger 240 and circulates and returns to the recycle compressor 210. However, when the liquefaction device 2 assists the air separation plant 1 to start, the recycle compressor 210 does not work, so that the gas output from the heat medium output end of the heat exchanger 240 needs to be dispersed to ensure the normal operation of the cooling device. As for the specific diffusion manner, there may be, but not limited to, the following two cases:
because the circulation return pipeline 260 is connected with the medium input pipeline 270 of the liquefaction device 2, and the medium input pipeline 270 can be communicated with the outside necessarily, the gas output by the heat medium output end of the heat exchanger 240 can be directly diffused into the external environment through the circulation return pipeline 260 and the medium input pipeline 270, so that the improvement of the existing device is smaller and the implementation is easier; or
The third pipeline 5 with the second vent valve 510 is connected to the medium return pipeline, the gas output from the heat medium output end of the heat exchanger 240 is released to the external environment through the third pipeline 5, meanwhile, in order to ensure the normal operation of the liquefaction device 2, a fourth stop valve 261 is arranged on the circulation return pipeline 260, the fourth stop valve 261 is positioned between the medium input pipeline 270 and the third pipeline 5, when the air separation plant 1 is started, the fourth stop valve 261 is closed, the second vent valve 510 is opened, when the air separation plant 1 is started, the fourth stop valve 261 is opened, the second vent valve 510 is closed, the purpose of the invention can be achieved, and the protection scope of the invention is also included.
Further, as shown in fig. 1, the raw material processing apparatus includes a raw material air compressor 10 and a molecular sieve adsorber 20, an input end of the molecular sieve adsorber 20 is connected to an output end of the raw material air compressor 10, and an output end of the molecular sieve adsorber 20 is communicated with an output end of the raw material processing apparatus.
The raw material processing device comprises a raw material air compressor 10 and a molecular sieve adsorber 20, the raw material air compressor 10 can compress raw material air into air with certain pressure, the molecular sieve adsorber 20 can remove components harmful to the air separation equipment 1 and the liquefaction device 2, such as water vapor, carbon dioxide, acetylene, propylene, propane, nitrous oxide and the like in the compressed air, and the obtained dry and clean air is used by the air separation equipment 1 and the liquefaction device 2 so as to ensure the normal operation of the air separation equipment 1 and the liquefaction device 2.
It will be understood that the lines in fig. 1 and 2 where some of the conduits intersect are broken, but are intended to illustrate that the two conduits are not in communication, rather than to indicate that one conduit is broken at that location.
In the above embodiment, as shown in fig. 2, the first control unit includes the first cut-off valve 310; the second control unit includes a second cut-off valve 410.
Preferably, as shown in FIG. 2, the first control unit further includes a third cut-off valve 320 and a first air release valve 330, the third cut-off valve 320 being disposed adjacent to the first cut-off valve 310, the first air release valve 330 being located between the first cut-off valve 310 and the third cut-off valve 320.
The first stop valve 310 is arranged on the first pipeline 3, the second stop valve 410 is arranged on the second pipeline 4, and the on-off of the first pipeline 3 and the second pipeline 4 can be effectively controlled through the on-off of the first stop valve 310 and the second stop valve 410, so that the structure is simple, and the control is reliable. Specifically, when the air separation plant 1 is started, the first stop valve 310 and the second stop valve 410 are opened, and the cooling device of the liquefaction device 2 is started, that is, the liquefaction device 2 can be used to assist in starting the air separation plant 1; when the air separation plant 1 is substantially completely started up, the first stop valve 310 and the second stop valve 410 are closed, and the cooling device of the liquefaction device 2 is closed, so that the air separation plant 1 and the liquefaction device 2 can be normally produced according to the respective production processes.
The first control unit further comprises a third stop valve 320 and a first vent valve 330, namely, two stop valves and one vent valve are arranged on the first pipeline 3, so that the first pipeline 3 can be reliably cut off after the air separation plant 1 is started, and the fluid medium in the liquefaction device 2 is prevented from being polluted by air leaked from the first pipeline 3 in normal operation. Specifically, when the air separation plant 1 is started, the first stop valve 310 and the second stop valve 410 are opened, and the first vent valve 330 is closed, so that the first pipeline 3 is conducted; when the air separation plant 1 is started up, the first stop valve 310 and the second stop valve 410 are closed, and the first vent valve 330 is opened to check whether the first pipeline 3 leaks, so that measures can be taken in time.
It is worth to be noted that, because the two ends of the second pipeline 4 are high-purity fluid media flowing during normal operation, the risk of pollution is relatively low, and only one stop valve needs to be arranged.
In the above embodiment, the exterior of the first pipe 3 and the exterior of the second pipe 4 are wrapped with insulation.
Preferably, the insulation material wrapped outside the first pipe 3 is a mineral wool material; the heat insulation material wrapped outside the second pipeline 4 is a polyurethane foam material.
The heat insulation materials are wrapped outside the first pipeline 3 and the second pipeline 4, so that the cold loss of fluid media in the first pipeline 3 and the second pipeline 4 can be reduced, the utilization rate of cold is improved, and the starting time of the air separation equipment 1 is further shortened.
Wherein, the mineral wool material with general heat preservation performance is wrapped outside the first pipeline 3, certainly not limited to the mineral wool material, because the air output by the raw material processing device flows in the first pipeline 3, and the air is only subjected to preliminary precooling by the cooling tower, so that the temperature is not particularly low, and the heat preservation can be carried out by using the common mineral wool material; the air which is deeply refrigerated by the cooling device flows in the second pipeline 4, the temperature of the air is lower, and the air is conveyed to the air separation plant 1 for starting the air separation plant 1, so that a polyurethane foaming material with relatively good heat insulation performance needs to be adopted, and certainly, other heat insulation materials with relatively good heat insulation performance can be adopted, and the loss of cold energy can be effectively reduced.
It is worth to say that, because the first pipeline 3 is completely positioned outside the cold box, the whole pipeline needs to be wrapped with a heat-insulating material; the second pipeline 4 may be partially located inside the cold box and partially located outside the cold box, and since the temperature inside the cold box is very low, the part located outside the cold box is only required to be wrapped with the thermal insulation material.
In the above embodiment, the liquefaction apparatus 2 is the single expansion liquefaction apparatus 2 with the refrigerator 230; or, the liquefaction device 2 is a high-low pressure two-stage expansion liquefaction device 2, the cooling device of the high-low pressure two-stage expansion liquefaction device 2 includes two booster expanders 220, which are a low-pressure stage booster expander 220 and a high-pressure stage booster expander 220, respectively, and when the air separation plant 1 is started, only the low-pressure stage booster expander 220 is started.
The liquefaction plant 2 is a single expansion liquefaction plant 2 with a refrigerating machine 230, that is, the cooling plant includes only one additional expansion machine, but the refrigerating machine 230 is also connected between the booster expansion machine 220 and the heat exchanger 240, and the refrigerating machine 230 can further increase the cooling capacity delivered to the air separation plant 1 by the cooling plant, thereby further shortening the start-up time of the air separation plant 1.
The liquefaction device 2 is a high-low pressure two-stage expansion liquefaction device 2, and only a low-pressure stage expansion machine is used for assisting the starting of the air separation plant 1 because most of the metallurgical air separation plant 1 is a full low-pressure flow, so that only the gas pressure output by the low-pressure stage expansion machine is matched with the air separation plant 1.
Naturally, the variety of the liquefaction plant 2 is various, and is not limited to the two cases, and they are not listed here, but those skilled in the art should understand that the cooling device of the liquefaction plant 2 is used to assist the air separation plant 1 in cooling, which is in accordance with the design idea and spirit of the present application, and therefore, all of them should be within the protection scope of the present application.
In the above embodiment, as shown in fig. 1, the return pipe includes the nitrogen return pipe 71, the oxygen return pipe 72, and the dirty nitrogen return pipe, and one end of the second pipe 4 is connected to the nitrogen return pipe 71.
One end of the second pipeline 4 is connected to the nitrogen return pipe 71, because the input end of the nitrogen return pipe 71 is positioned at the uppermost part of the upper tower 63 relative to other return pipes, and the nitrogen return pipe passes through the safety valve pipeline above the upper tower 63 to discharge the cold box, for the units of the existing air separation plant 1 and the liquefaction device 2, the second pipeline 4 can be directly connected to the pipe of the safety valve pipeline discharge cold box, so the implementation is convenient, and the investment is saved; as for the other end of the second pipeline 4, the cold box of the liquefaction device 2 is very small, and direct sand raking transformation can be performed. Of course, for newly built units of air separation plant 1 and liquefaction device 2, this pipeline can be directly arranged in the cold box by using the present application, and it is better to make the cold box of air separation plant 1 and the cold box of liquefaction device 2 on the same concrete foundation, and even embed liquefaction device 2 in the cold box of air separation plant 1, so that the pipeline can be designed in a targeted optimization manner. And for the first pipe 3, since it is outside the cold box, it is easy to reform.
Of course, it should be understood by those skilled in the art that since the fluid medium flowing through the air separation plant 1 is air and no product is collected, one end of the second pipe 4 may also be connected to the oxygen return pipe 72 or the waste nitrogen return pipe 73, or when the return pipe further includes return pipes for other media, such as an argon return pipe, etc., the return pipes may also be connected to the pipelines of the heat exchange devices 40, so that the effect of shortening the start-up time of the air separation plant 1 can be achieved as long as the matching of the pressure levels is considered and measures for preventing product contamination during operation are taken, and the basic principles are the same, which are not listed herein but fall within the protection scope of the present invention.
In the above embodiment, the air separation plant 1 is the air separation plant 1 of the external compression flow.
Compared with the air separation plant 1 in the internal compression process, the air separation plant 1 in the external compression process does not need to produce liquid, the refrigerating capacity of the configured turboexpander 30 is relatively smaller, and only the cold loss in normal production needs to be supplemented, so that the starting time is longer, the starting is assisted by the liquefying device 2, and the energy-saving significance is more remarkable. Of course, the air separation plant 1 in the internal compression process may also utilize the liquefaction device 2 to assist the startup thereof, and also can achieve the purpose of shortening the startup time and saving energy consumption.
The following describes the air separation system provided by the present invention in detail with reference to some specific embodiments of the present invention.
Example one
As shown in fig. 1 and 2, the air separation plant 1 is an air separation plant 1 of a full low-pressure, external compression flow scheme, and outputs nitrogen gas, oxygen gas and waste nitrogen, the liquefaction plant 2 is a nitrogen gas single-expansion liquefaction plant 2 with a refrigerator 230, and a return gas output from the liquefaction plant 2 is connected to a nitrogen gas return pipe 71 at the top of an upper column 63.
As shown in fig. 1, the air separation plant 1 includes a raw material processing device, a refrigeration device, a heat exchange device 40, a rectification tower, a return flow pipeline and a medium output pipeline, the principle processing device includes a raw material air compressor 10 and a molecular sieve adsorber 20, the refrigeration device includes two turboexpanders 30, the heat exchange device 40 includes a main heat exchanger, a subcooler 50 is further connected between the return flow pipeline and the main heat exchanger, the rectification tower includes a lower tower 61, a main condensation evaporator 62 and an upper tower 63, the return flow pipeline includes a nitrogen return flow pipe 71, an oxygen return flow pipe 72 and a waste nitrogen return flow pipe 73, the medium output pipeline includes a nitrogen output pipe 81, an oxygen output pipe 82 and a waste nitrogen output pipe 83, the nitrogen return flow pipe 71 is communicated with the nitrogen output pipe 81, the oxygen return flow pipe 72 is communicated with the oxygen output pipe 82, and the waste nitrogen return flow pipe 73 is communicated with the waste nitrogen output pipe.
Specifically, as shown in fig. 1, the output end of the raw material air compressor 10 is connected to the input end of the molecular sieve adsorber 20, the output end of the molecular sieve adsorber 20 is connected to the heat medium input end of the main heat exchanger and the input end of the pressurizing portion of the turbo expander 30, the cold medium output end of the main heat exchanger is connected to the lower tower 61 of the rectifying tower, the output end of the expansion portion of the turbo expander 30 is connected to the upper tower 63 of the rectifying tower, the input end of the reflux pipeline is connected to the medium output end of the rectifying tower, the output end of the reflux pipeline is connected to the cold medium input end of the heat exchanging device 40, and the heat medium output end of the heat exchanging device 40 is connected to the medium output pipeline.
When the air separation plant 1 works normally, dry clean air output by the raw material processing device is divided into two paths, one path of the dry clean air enters the heat exchange device 40, exchanges heat with low-temperature media (low-temperature nitrogen, low-temperature oxygen and low-temperature waste nitrogen) input into the heat exchange device 40 by a backflow pipeline, is cooled, and then enters a lower tower 61 of the rectifying tower; the other path enters a refrigerating device, and enters an upper tower 63 of the rectifying tower after deep refrigeration and temperature reduction in the refrigerating device; the upper tower 63 is matched with the lower tower 61, so that air is separated into low-temperature nitrogen, low-temperature oxygen and low-temperature waste nitrogen, and the low-temperature nitrogen, the low-temperature oxygen and the low-temperature waste nitrogen are output from a medium output end of the upper tower 63; the output low-temperature nitrogen, low-temperature oxygen and low-temperature waste nitrogen respectively enter the nitrogen return pipe 71, the oxygen return pipe 72 and the waste nitrogen return pipe 73, then flow to the heat exchange device 40, and are output to the corresponding nitrogen output pipe 81, oxygen output pipe 82 and waste nitrogen output pipe 83 from the heat medium output end after exchanging heat with air in the heat exchange device 40.
As shown in fig. 2, the liquefaction plant 2 includes a medium input line 270, a recycle compressor 210, a cooling device including a booster expander 220, a refrigerator 230, and a heat exchanger 240, a recycle return line 260, and a liquid storage device 250; the medium input pipeline 270 is a nitrogen input pipeline, the circulating compressor 210 is a circulating nitrogen compressor, the liquid storage device 250 is a liquid nitrogen storage tank, and the heat exchanger 240 is a liquefied plate heat exchanger.
Specifically, as shown in fig. 2, the medium input pipe 270 is connected to an input end of the circulation compressor 210 and one end of the circulation return pipe 260, an output end of the circulation compressor 210 is connected to an input end of the pressure increasing portion 221 of the pressure increasing expander 220, an output end of the pressure increasing portion 221 is connected to a heat medium input end of the heat exchanger 240 and an input end of the expansion portion 222 of the pressure increasing expander 220, an output end of the expansion portion 222 is connected to a cold medium input end of the heat exchanger 240, a heat medium output end of the heat exchanger 240 is connected to the other end of the circulation return pipe 260, a cold medium output end of the heat exchanger 240 is connected to the liquid storage device 250, and the refrigerator 230 is further connected between the pressure increasing portion 221 and.
When the liquefaction device 2 works normally, nitrogen enters the liquefaction device 2 through the medium input pipeline 270, then enters the circulating compressor 210 to be primarily compressed in the circulating compressor 210, then enters the pressurization part 221 of the pressurization expander 220 to be secondarily compressed, and then enters the heat exchanger 240; the nitrogen entering the heat exchanger 240 is divided into two paths, one path of nitrogen enters the expansion part 222 of the booster expander 220 for deep refrigeration after being preliminarily cooled, and returns to the heat exchanger 240 after deep refrigeration, and exchanges heat with the other path of nitrogen in the heat exchanger 240, so that the other path of fluid medium can be fully exchanged heat and cooled in the heat exchanger 240 to be changed into liquid nitrogen to be output from the cold medium output end of the heat exchanger 240, and the low-pressure nitrogen output from the hot medium output end of the heat exchanger 240 after heat exchange returns to the input end of the circulating compressor 210 through the circulating reflux pipeline 260, and enters the circulating compressor 210 to be continuously compressed after being converged with the nitrogen input from the medium input pipeline; and the liquid nitrogen output from the cold medium output end of the heat exchanger 240 enters the liquid storage device 250 for storage.
Next, the air separation plant 1 and the liquefaction device 2 are appropriately modified to obtain the air separation system capable of being started quickly, specifically:
the method comprises the following steps: a first pipeline 3 is connected between the outlet of the molecular sieve adsorber 20 of the air separation plant 1 and the inlet pipe of the pressurizing part 221 of the liquefaction device 2, so that dry clean air processed by the raw material processing device of the air separation plant 1 can enter the cooling device of the liquefaction device 2; two stop valves and an emptying valve (a first stop valve 310, a third stop valve 320 and a first emptying valve 330) are arranged on the first pipeline 3 so as to ensure that the first pipeline 3 can be reliably cut off after the air separation plant 1 is started; the pipeline is wrapped with mineral wool materials for heat preservation. Since the first pipes 3 are all outside the cold box, the modification is easy.
Step two: a second pipeline 4 is connected between the cold medium output end of the plate heat exchanger of the liquefying device 2 and a nitrogen return pipe 71 fixed on an upper tower 63 of the air separation plant 1, so that the low-temperature air output by the liquefying device 2 can enter the air separation plant 1 for heat exchange to assist the starting of the air separation plant 1; a stop valve (a second stop valve 410) is arranged on the second pipeline 4 to ensure that the second pipeline 4 can be cut off after the air separation plant 1 is started; the part of the pipeline, which is positioned outside the cold box, is wrapped by polyurethane foaming material for heat preservation.
For newly building units of the air separation plant 1 and the liquefaction device 2, the connecting pipeline can be directly arranged in the cold box, the air separation cold box and the liquefaction cold box are preferably made on the same concrete foundation, and even the liquefaction device 2 is embedded in the air separation cold box, so that the pipeline can be designed in a targeted optimization manner.
For the units of the existing air separation plant 1 and the liquefaction device 2, in order to facilitate implementation and save investment, the safety valve pipeline of the upper tower 63 can be utilized to connect the second pipeline 4 to the pipe of the safety valve outlet cold box at the top of the upper tower 63, and the cold box of the liquefaction device 2 is very small, so that the direct sand raking transformation can be carried out.
Step three: a third line 5 of a second vent valve 510 is connected to the recirculation line 260 at the outlet for the heat medium of the plate heat exchanger of the liquefaction plant 2 for venting the low-pressure air.
Step four: check whether there is a shut-off valve on the recirculation return line 260, and if not, add a shut-off valve (fourth shut-off valve 261).
Thus, the modification of the air separation plant 1 and the liquefaction plant 2 is completed. Specifically, when the air separation plant 1 is started, the following steps are performed:
the method comprises the following steps: recording an outlet valve of the circulating nitrogen press as a fifth stop valve 211, and closing inlet and outlet valves of the circulating nitrogen press, namely closing the fourth stop valve 261 and the fifth stop valve 211;
step two: when the air separation plant 1 is started, the original diffused compressed air rich in the air compressor is sent to the liquefying device 2 through the first pipeline 3, the refrigerating machine 230 and the booster expansion machine 220 of the liquefying device 2 are started for auxiliary refrigeration, and then the air is sent to the air separation plant 1 through the second pipeline 4 for cold energy recovery;
step three: when the liquid level of the main condensation evaporator 62 of the air separation plant 1 is close to the working height, the booster turbine and the refrigerator 230 of the liquefaction device 2 are closed;
step four: the first and second pipes 3 and 4 are cut off, i.e., the first, second, and third cut-off valves 310, 410, and 320 are closed, the first vent valve 330 is opened, and the third pipe 5 is cut off, i.e., the second vent valve 510 is closed.
The rest of the process was carried out as described for the air separation plant 1 and the liquefaction plant 2.
When the air separation plant 1 is started, the raw material processing device can process raw material air into dry and clean air to be output, wherein a part of air enters the cooling device of the liquefying device 2 through the first pipeline 3, is cooled into low-temperature fluid in the cooling device and then is conveyed to the nitrogen return pipe 71 of the air separation plant 1 through the second pipeline 4, and enters the main heat exchanger of the air separation plant 1 through the nitrogen return pipe 71, so that cold energy is contributed in the main heat exchanger and is used in the starting stage of the air separation plant 1, and the refrigerating capacity of the cooling device is very large, so that the cold energy supplied to the air separation plant 1 is also considerable, thereby greatly shortening the starting time of the air separation plant 1 and saving considerable energy. When the liquid level of the main condensing evaporator 62 of the air separation plant 1 is close to the working height, that is, the air separation plant 1 has basically finished being started up, the first pipeline 3 and the second pipeline 4 are cut off, and meanwhile, the cooling device of the liquefaction device 2 is closed, so that the air separation plant 1 can normally work.
Therefore, the essence of the present embodiment is: the output end of a raw material output device of the air separation plant 1 is connected with a dry air pipeline to a cooling device of the liquefaction device 2, and the output end of the cooling device of the liquefaction device 2 is connected with a low-temperature fluid pipeline to a backflow pipeline near a rectifying tower of the air separation plant 1, so that the refrigerating capacity of the cooling device of the liquefaction device 2 can be provided for the starting stage of the air separation plant 1, namely not only a refrigerating device (generally a turboexpander 30) of the air separation plant 1, but also the cooling device of the liquefaction device 2 is included, and the refrigerating capacity of the cooling device of the liquefaction device 2 is far greater than that of the refrigerating device of the air separation plant 1, so that the starting time of the air separation plant 1 is decisively influenced, the starting time of the air separation plant 1 is greatly shortened, the energy consumption is remarkably saved, great influence can be generated on industries such as metallurgy, and the like, and a new era of the.
When the liquefaction device 2 is normally used, the nitrogen compressed by the recycle compressor 210 is used for refrigeration, and the energy consumption of the recycle compressor 210 during operation is very large; when the liquefaction device 2 is used for assisting the air separation plant 1 to start, the liquefaction device 2 utilizes the air processed by the raw material processing device of the air separation plant 1 to refrigerate, and because the raw material processing device is in a running state when the air separation plant 1 is started, part of the processed air is supplied to the liquefaction device 2, the utilization rate of the air processed by the liquefaction device is improved, the running of the high-power circulating compressor 210 of the liquefaction device 2 is avoided, and therefore energy is greatly saved.
EXAMPLE two (not shown)
The difference from the first embodiment is that the liquefaction device 2 is an oxygen single expansion liquefaction device 2, that is, the liquefaction device 2 using oxygen is used to assist the start-up of the air separation plant 1, and the return gas of the second pipeline 4 is connected to the oxygen return pipe 72 (of course, the return gas may be connected to the nitrogen return pipe 71 or the waste nitrogen return pipe 73). Correspondingly, the medium input pipeline 270 of the liquefaction device 2 is an oxygen input pipeline, the circulation compressor 210 is a circulation oxygen compressor, and the liquid storage device 250 is a liquid oxygen storage tank, which also shortens the start-up time of the air separation plant 1, and the basic principle thereof is the same as that of the first embodiment, and is not described herein again.
EXAMPLE three (not shown)
The difference from the first embodiment is that the liquefaction device 2 is a high-low pressure two-stage expansion liquefaction device 2 for nitrogen, the return gas of the second pipeline 4 is connected to the nitrogen return pipe 71 of the upper tower 63, but when the auxiliary air separation plant 1 is started, only the low pressure stage booster expansion machine 220 is started to ensure that the pressure of the gas input into the air separation plant 1 is matched with that of the air separation plant 1, the effect of shortening the starting time of the air separation plant 1 is also achieved, the basic principle is the same, and details are not repeated herein.
EXAMPLE four (not shown)
The difference from the first embodiment is that the air separation plant 1 and the liquefaction plant 2 are newly built, and the return flow access point of the second pipeline 4 is arranged on the waste nitrogen return pipe 73, which is obtained by using the operation parameters of the raw material air during refrigeration through relatively accurate calculation according to the refrigeration capacity (i.e. liquefaction capacity) of the liquefaction plant 2, and the effect of shortening the start-up time of the air separation plant 1 is also achieved, and the basic principle is the same, and is not described herein again.
In conclusion, the air separation system provided by the invention utilizes the cooling device of the liquefying device 2 to assist in refrigeration, and the liquefying device 2 needs to produce liquid, so that the refrigerating capacity of the cooling device is very large, the starting time of the air separation plant 1 can be greatly shortened, the energy consumption of industries such as metallurgy and the like can be obviously reduced, and the purpose of energy conservation can be realized; meanwhile, the air source of the circulating compressor 210 is used for refrigeration of the normal liquefaction device 2, but the air released by the raw material processing device of the air separation plant 1 is used for refrigeration, so that the utilization rate of the air processed by the raw material processing device is improved, the energy consumption of the liquefaction device 2 during refrigeration is also saved, and the energy is also greatly saved.
In addition, since the gas users of the metallurgical enterprises are in discontinuous use, but the air separation plant 1 is continuously produced, in order to reduce the waste of the gas product, the related enterprises are generally equipped with a separate liquefaction device 2 to liquefy and store the surplus gas product. Before the air separation plant 1 is normally started up, the liquefaction plant 2 is often also shut down, just to use it to assist in refrigeration, since no acceptable gas product has been produced. Therefore, the technical scheme can achieve the purpose of shortening the starting time of the air separation plant 1 only by slightly modifying the existing air separation plant 1 and the liquefying device 2, thereby generating considerable energy-saving effect, being convenient for popularization and having very good application prospect.
In the present invention, the terms "first", "second", "third", "fourth", "fifth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the term "plurality" means two or more unless expressly limited otherwise. The terms "mounted," "connected," "fixed," and the like are to be construed broadly, and for example, "connected" may be a fixed connection, a removable connection, or an integral connection; "coupled" may be direct or indirect through an intermediary. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the description herein, the description of the terms "one embodiment," "some embodiments," "specific embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (11)

1. An air separation system, comprising:
the air separation equipment comprises a raw material processing device, a heat exchange device and a return pipeline, wherein the raw material processing device can output dry and clean air, and the output end of the return pipeline is connected with the cold medium input end of the heat exchange device;
one end of the first pipeline is communicated with the output end of the raw material processing device, and a first control unit for controlling the on-off of the first pipeline is arranged on the first pipeline; one end of the second pipeline is communicated with the backflow pipeline, and a second control unit for controlling the on-off of the second pipeline is arranged on the second pipeline;
the input end of the cooling device is communicated with the other end of the first pipeline, and the output end of the cooling device is communicated with the other end of the second pipeline;
when the air separation plant is started, the first control unit controls the first pipeline to be conducted, and the second control unit controls the second pipeline to be conducted.
2. The air separation system according to claim 1,
the first control unit includes a first shut-off valve;
the second control unit includes a second shutoff valve.
3. The air separation system according to claim 2,
the first control unit further includes a third stop valve disposed adjacent to the first stop valve and a first dump valve disposed between the first stop valve and the third stop valve.
4. The air separation system according to claim 1,
and the outside of the first pipeline and the outside of the second pipeline are wrapped with heat insulation materials.
5. The air separation system according to claim 4,
the heat insulation material wrapped outside the first pipeline is a mineral wool material;
the heat insulation material wrapped outside the second pipeline is a polyurethane foam material.
6. The air separation system according to any one of claims 1 to 5,
the cooling device comprises a booster expander and a heat exchanger, the booster expander comprises a booster part and an expansion part, the input end of the booster part is communicated with the input end of the cooling device, the output end of the booster part is communicated with the heat medium input end of the heat exchanger and the input end of the expansion part, the output end of the expansion part is communicated with the cold medium input end of the heat exchanger, and the cold medium output end of the heat exchanger is communicated with the output end of the cooling device;
when the air separation plant is started, the heat medium output end of the heat exchanger is communicated with the outside and used for diffusing the fluid medium output from the heat medium output end of the heat exchanger.
7. The air separation system according to claim 6,
a circulating reflux pipeline is arranged between a medium input pipeline of the liquefying device and a heat medium output end of the heat exchanger;
fluid media output by a heat medium output end of the heat exchanger sequentially flow through the circulating return pipeline and the medium input pipeline and then are discharged; or, a fourth stop valve close to the medium input pipeline is arranged on the circulating reflux pipeline, a third pipeline close to the heat medium output end of the heat exchanger is connected to the circulating reflux pipeline, a second emptying valve is arranged on the third pipeline, and fluid medium output by the heat medium output end of the heat exchanger is discharged through the third pipeline.
8. The air separation system according to claim 6,
the liquefaction device is a single expansion liquefaction device with a refrigerator; or
The liquefaction device is a high-low pressure two-stage expansion liquefaction device, the cooling device of the high-low pressure two-stage expansion liquefaction device comprises two booster expanders which are respectively a low-pressure stage booster expander and a high-pressure stage booster expander, and only the low-pressure stage booster expander is started when the air separation plant is started.
9. The air separation system according to any one of claims 1 to 5,
the raw material processing device comprises a raw material air compressor and a molecular sieve adsorber, wherein the input end of the molecular sieve adsorber is connected with the output end of the raw material air compressor, and the output end of the molecular sieve adsorber is communicated with the output end of the raw material processing device.
10. The air separation system according to any one of claims 1 to 5,
the backflow pipeline comprises a nitrogen backflow pipe, an oxygen backflow pipe and a waste nitrogen backflow pipe, and one end of the second pipeline is connected to the nitrogen backflow pipe.
11. The air separation system according to any one of claims 1 to 5,
the air separation equipment is the air separation equipment of an external compression process.
CN201611022494.9A 2016-11-17 2016-11-17 Air separation system Expired - Fee Related CN108072235B (en)

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