CN116538763A - Air separation device and air separation method - Google Patents

Air separation device and air separation method Download PDF

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Publication number
CN116538763A
CN116538763A CN202310450033.5A CN202310450033A CN116538763A CN 116538763 A CN116538763 A CN 116538763A CN 202310450033 A CN202310450033 A CN 202310450033A CN 116538763 A CN116538763 A CN 116538763A
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CN
China
Prior art keywords
additional
heat exchanger
main heat
air separation
stream
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202310450033.5A
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Chinese (zh)
Inventor
李晓旭
曹建伟
邢博
付永兴
陈川川
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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Application filed by LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude filed Critical LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority to CN202310450033.5A priority Critical patent/CN116538763A/en
Publication of CN116538763A publication Critical patent/CN116538763A/en
Pending legal-status Critical Current

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Classifications

    • 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
    • F25J3/04406—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
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/04084—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
    • 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
    • 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
    • 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
    • F25J3/04296—Claude expansion, i.e. expanded into the main or 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
    • F25J3/04248—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.
    • F25J3/04387—Details relating to the work expansion, e.g. process parameter etc. using liquid or hydraulic turbine 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
    • F25J3/04248—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
    • F25J3/04642—Recovering noble gases from air
    • F25J3/04648—Recovering noble gases from air argon
    • F25J3/04654—Producing crude argon in a crude argon column
    • F25J3/04666—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system
    • F25J3/04672—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser
    • F25J3/04678—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser cooled by oxygen enriched liquid from high pressure column bottoms
    • 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
    • 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
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/50—Oxygen or special cases, e.g. isotope-mixtures or low purity O2
    • F25J2215/54—Oxygen production with multiple pressure O2
    • 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
    • F25J2240/10—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream 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
    • F25J2240/40—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
    • F25J2240/44—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval the fluid being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • 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

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

Abstract

The invention provides a space division device and a space division method. In the air separation plant, a feed line is used to feed at least a portion of the total feed gas from the main compressor to the rectification column system via the main heat exchanger, and a waste discharge line is used to discharge waste gas from the rectification column system via the main heat exchanger. The air separation plant also includes additional piping and additional expanders. An additional line leads from the position of the feed line before the main heat exchanger and leads to the position of the reject line between the main heat exchanger and the rectification column system. The additional expander is arranged in the additional pipeline, so that the flow in the additional pipeline is sent into the waste discharge pipeline after being expanded by the additional expander. The air separation equipment and the air separation method can adapt to different working conditions of air product quantity change.

Description

Air separation device and air separation method
Technical Field
The invention belongs to the field of space division, and relates to space division equipment and a space division method.
Background
Space division devices are widely used in various industries. Users using air separation plants are often faced with situations where the demand for air products, in particular gas products, is different in different time periods. For example, in the early stages of construction, the customer may only need a lower yield of gas product because the support facilities are not complete. In the latter stage, the amount of gaseous products required by the user is increasing as the supporting facilities are gradually maturing. The later period of time is used as a design working condition, and the earlier period of time is used as a low-yield working condition. Sometimes, the amount of air product, such as oxygen product, required for low production conditions is even less than half the amount of oxygen product required for design conditions.
The inventors analysis considered that in the case where the amount of air product required was significantly different under the design conditions and the low-yield conditions, the amount of feed air was also significantly different correspondingly under the two conditions. In this case, the main compressor can normally compress the feed air with a larger mass flow rate under the design condition. However, under low-yield conditions, the main compressor may not operate properly for feed air having a significantly reduced mass flow, e.g., a surge problem.
In this regard, the inventors further analyzed that, under low-yield conditions, it was possible to feed the main compressor with a mass flow rate exceeding that required, while the excess of feed air was not fed to the rectifying column system.
Thus, how to effectively utilize the excess portion of the feed air is a problem that needs to be further addressed.
Disclosure of Invention
The invention aims to provide air separation equipment and a method, which can adapt to different working conditions of air product quantity change, particularly significant change.
It is another object of the present invention to provide an air separation apparatus and method that can effectively utilize the entire feed air fed.
The invention provides an air separation apparatus. The air separation plant comprises a feed line and a waste discharge line. The feed line is for feeding at least a portion of the total feed gas from the main compressor to the rectification column system via the main heat exchanger, and the waste discharge line is for discharging waste gas from the rectification column system via the main heat exchanger. The air separation plant also includes additional piping and additional expanders. An additional line leads from the position of the feed line before the main heat exchanger and leads to the position of the reject line between the main heat exchanger and the rectification column system. The additional expander is arranged in the additional pipeline, so that the flow in the additional pipeline is sent into the waste discharge pipeline after being expanded by the additional expander.
In one embodiment, the air separation plant further comprises a regulating device for regulating the mass flow of the stream flowing from the feed line to the additional line.
In one embodiment, the air separation plant further comprises an additional compressor. The additional compressor is disposed in the additional line upstream of the additional expander such that the stream in the additional line is pressurized by the additional compressor and then expanded into the additional expander.
In one embodiment, the additional line reaches the additional expander downstream of the additional compressor via a first location and a second location of the main heat exchanger in sequence, wherein the first location is a hotter location relative to the second location.
In one embodiment, the air separation plant further comprises an aftercooler. An aftercooler is disposed in the additional line between the additional compressor and the main heat exchanger.
In one embodiment, the first location is the warm end of the main heat exchanger; and/or the second location is an intermediate location of the primary heat exchanger.
In one embodiment, the additional compressor and the additional expander are a boost end and an expansion end, respectively, of the expansion-booster that are mechanically coupled.
The invention also provides a space division method, which uses space division equipment. The air separation process includes feeding at least a portion of the total feed gas from a main compressor of the air separation plant to the rectification column system via a main heat exchanger as a feed stream to the rectification column system, and discharging an exhaust gas from the rectification column system via the main heat exchanger. The air separation process further includes, under predetermined conditions, withdrawing a portion of the total feed gas from the main heat exchanger as an additional stream and passing the additional stream through the expansion process to the offgas at a location between the main heat exchanger and the rectification column system.
In one embodiment, the additional stream is subjected to a pressure boost treatment prior to the expansion treatment.
In one embodiment, the additional stream is cooled via the main heat exchanger between the pressure boost treatment and the expansion treatment.
In one embodiment, the additional stream is cooled after the supercharging process first via an aftercooler and then via a main heat exchanger.
In one embodiment, the additional stream is taken in from the warm end of the main heat exchanger and taken out from an intermediate position of the main heat exchanger as it is cooled via the main heat exchanger; so that after expansion the pressure and temperature of the additional stream is reduced to a level comparable to the pressure and temperature of the exhaust gas.
In one embodiment, the ratio of the mass flow of the additional stream to the mass flow of the total feed gas is made to be between 5% and 20%. The ratio of the mass flow of the raw material flow of the rectifying tower system under the preset working condition to the mass flow of the raw material flow under other working conditions is 40% -60%.
In the above-described air separation plant and method, under conditions where a large amount of air product, particularly gas product, is required, substantially all of the total feed gas may be fed to the rectification column system as a feed stream to the rectification column system without the use of additional piping. In conditions where a reduced amount of air product is required, a portion of the total feed gas fed in the feed line may be diverted through the additional line, and thus the total feed gas passing through the main compressor may include this portion of the feed gas diverted from the additional line in addition to the portion of the feed gas required as a feed stream. In this way, the mass flow of the total feed gas through the main compressor is not too low to cause a malfunction. Therefore, the air separation equipment and the air separation method can adapt to different working conditions of air product quantity change, and particularly the working condition that the air product quantity is obviously changed to cause faults.
In the air separation equipment and the air separation method, under the working condition that the air product quantity is reduced, the part of feed gas led out from the additional pipeline is expanded, refrigerated and then is converged into the waste gas, so that the waste gas and the waste gas absorb heat in the main heat exchanger together, and additional cold energy is provided for the whole air separation equipment, particularly the rectifying tower system, so that more liquid products can be produced. The liquid product may be converted directly into a liquid product for storage, in addition to the desired amount of air product. Thus, the portion of the feed gas exiting the additional line is also utilized to provide additional refrigeration, and thus the above-described air separation apparatus and method can effectively utilize the entire feed air fed.
Further, in the above-described air separation plant and method, the part of the feed gas led out from the additional line is introduced into the exhaust gas and then fed into the main heat exchanger together. That is, this part of the feed gas directly utilizes the passage in the main heat exchanger through which the exhaust gas passes, so that the change in the configuration of the main heat exchanger can be avoided to the maximum extent, and the overall equipment cost can be reduced.
Drawings
The advantages and spirit of the present invention may be further understood by reference to the following detailed description of the invention and the accompanying drawings.
Fig. 1 is a schematic diagram of an exemplary air separation apparatus according to the present invention.
Fig. 2 is a schematic diagram of an exemplary air separation apparatus as a comparative example.
Detailed Description
Specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention should be understood not to be limited to such an embodiment described below, and the technical idea of the present invention may be implemented in combination with other known technologies or functions, or other technologies identical to those known technologies.
The terms "first" and "second" are used for descriptive purposes only and are not intended to be limiting with respect to time sequence, number, or importance, and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of features indicated, but merely to distinguish one feature from another feature in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly specified otherwise. Likewise, the appearances of the phrase "a" or "an" in this document are not meant to be limiting, but rather describing features that have not been apparent from the foregoing. Likewise, unless a particular quantity of a noun is to be construed as encompassing both the singular and the plural, both the singular and the plural may be included in this disclosure. Likewise, modifiers similar to "about" and "approximately" appearing before a term in the text generally include the present number, and their specific meaning should be understood in conjunction with the context.
It should be understood that in the present invention, "at least one (secondary)" means one (secondary) or a plurality of (secondary). "and/or" is used to describe association relationships of associated objects, meaning that there may be three relationships, e.g., "a and/or B" may mean: only a, only B and both a and B are present, wherein a, B may be singular or plural.
As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.
In practical engineering, for a set of air separation plants, the demand of users for air products, in particular gas products, that can be produced by the air separation plant often varies. Often, the amount of air product required varies from 75% to 105% of the design operating conditions. At this time, the requirement for the load (1 load) capacity or performance of the individual devices in the air separation plant is not so high, and the air separation plant can generally accommodate such variations.
Sometimes, however, the amount of air product required by the user fluctuates over a vast range of design conditions. For example, in the early stages of construction, because the supporting facilities are not complete, the amount of air products required by the user may be small, and then the air products are lifted or climbed to a great extent to cope with the mature design conditions of the supporting facilities. The initial condition where the demand for air product is small may be referred to as a low-yield (turn down) condition, and may also be referred to as a ramp-up (ramp-up) condition. As an example, the demand for air products during low-production conditions may be, for example, only around 50% of the demand during design conditions. As a more specific example, the user needs the air separation plant to be initially in a stage where the production capacity of the oxygen product is low, and then gradually transition or abrupt transition to a stage where the production capacity of the oxygen product is high. The lower capacity phase may be considered the air separation plant 10 to be in a low-yield mode (or referred to as a low-yield mode), while the higher capacity phase may be considered the air separation plant 10 to be in a design mode (or referred to as a design mode).
The main compressor for compressing the feed gas is prepared for the design conditions, so that the feed gas with a larger mass flow rate can be dealt with under the design conditions. However, under low-yield conditions, the mass flow of feed gas as a feed stream will correspondingly be significantly reduced due to the significantly reduced amount of air product required. At this time, for feed gas with too small mass flow, the main compressor will have a surge problem, which not only causes an increase in energy consumption of the air separation plant, but also is unfavorable for machine operation, and even causes a failure of the whole air separation plant to work.
The low-yield condition may refer to a particular condition having a lower amount of air product than the design condition, or may refer to any one of a plurality of conditions having a lower amount of air product than the design condition. In actual engineering, the low-yield condition may gradually transition to the design condition, i.e., the air product amount may gradually increase from a lower value to a higher value continuously or intermittently. The low-yield condition may also be increased abruptly to the design condition, i.e., the air product amount may be changed abruptly from a lower value to a higher value. This can be specifically controlled depending on the actual situation.
By "air product" is meant various products separated from the air by the rectifying column system of the air separation plant that can be directly utilized or stored, including oxygen products, nitrogen products, argon products, and the like. Air products include "gas products" that exist in gaseous form, as well as "liquid products" that exist in liquid form and are thus particularly convenient for storage. The gaseous products may include oxygen products, nitrogen products, argon products, and the like. The liquid product may include a liquid oxygen product, a liquid nitrogen product, a liquid argon product, and the like. By "liquid product" is meant all intermediate products in liquid form, including, for example, liquid oxygen products, liquid nitrogen products, liquid argon products, and the like, produced directly from the rectification column system of the air separation plant. It is to be understood that "liquid product" includes a first portion of the liquid product directly as a liquid product and also includes a second portion of the liquid product that will be vaporized in the main heat exchanger to be converted into a gaseous product. Taking the liquid oxygen product contained as liquid product in fig. 1 as an example, the liquid oxygen product comprises a second part of the liquid oxygen product (denoted by streams c31 and c32, corresponding to the low pressure oxygen product and the high pressure oxygen product, respectively) which eventually is vaporized in the main heat exchanger 1b and converted into an oxygen product, and a first part of the liquid oxygen product (denoted by stream c 33) which can be directly fed to a storage tank for storage as liquid oxygen product. From the foregoing, it can be seen that the second part of the liquid product finally recovers its cold energy into the rectifying tower system by heat exchange in the main heat exchanger, and the first part of the liquid product needs to carry the cold energy out of the rectifying tower system. Thus, the first part of the liquid product, which is directly a liquid product, is essentially more demanding in terms of the cold to be fed to the rectification column system and is difficult to obtain. In other words, the yield or productivity of the liquid product is high with respect to the construction requirements of the whole air separation plant and process.
By "yield" of liquid product is meant, for example, the ratio of moles of liquid product obtained per unit time to moles of the corresponding feed stream (i.e., feed air to the rectification column system), i.e., the conversion of the feed stream that can be used to characterize the total feed gas to liquid product by the cryogenic air separation plant. The yields are shown herein as a percentage of the molar amount. The number of moles of liquid product obtained per unit time can be scaled or characterized by the mass flow rate of liquid product and the number of moles of feed stream per unit time can be scaled or characterized by the mass flow rate of feed stream. For example, the mass flow of the feed stream or liquid product herein may be shown in terms of standard volumes of fluid fed or flowing per unit time, for example, in Nm3/h (standard cubic meters per hour). The mass flow of liquid product may also be referred to as the yield of liquid product. It will be appreciated that for a total feed gas feed amount that is substantially constant, the different yields of liquid product are directly reflected in the different yields of liquid product.
Analyzing and considering the above, the present invention is directed to an air separation apparatus and method that solve the above problems.
The inventors analysis considered that in the case where the amount of air product required was significantly different under the design conditions and the low-yield conditions, the amount of feed air was also significantly different correspondingly under the two conditions. In this case, the main compressor can normally compress the feed air with a larger mass flow rate under the design condition. However, under low-yield conditions, the main compressor may experience problems such as surge due to too small a mass flow of feed air through the main compressor, and malfunction. Accordingly, the present invention provides the following space division apparatus and method, which are intended to solve the above problems.
It is to be understood that the drawings are by way of example only and are not necessarily drawn to scale and that the scope of the invention should not be construed to be limited thereto.
Fig. 1 shows an exemplary air separation apparatus 10 according to the present invention. The air separation plant 10 comprises a feed line 81 and a waste line 82. Feed line 81 is used to feed at least a portion of total feed gas f0 from main compressor 61 to rectifying column system 2 via main heat exchanger 1. The exhaust line 82 is used to exhaust the offgas W0 from the rectifying column system 2 via the main heat exchanger 1.
A "compressor" is a device that is configured to compress a gaseous or at least partially gaseous stream, which pressurizes the stream while it is being compressed, while it is being warmed. The compressor may comprise a plurality of compression stages, wherein all compression stages are housed within the same housing or connected to the same drive shaft. In this case, the stream may be compressed in all or only a part of the compression stages. Each compression stage of the compressor may be, for example, a piston, screw, turbine, etc. An "expander" is a device that is configured to expand a stream, which, as it expands, cools the stream while depressurizing it. The expander may be, for example, a piston, screw, turbine, or the like. Typically, the stream is gaseous or at least partially gaseous. The expander may be coupled with other expanders or energy converters such as oil brakes, generators, additional compressors, etc., via a common shaft. When the expander is coupled to the compressor, the whole of the expander, the compressor, etc. may be referred to as an expansion booster. In an expansion-compressor, the compressor is driven by one or more expanders, i.e. the expansion work done in the expander is converted into compression work of the compressor. At this time, the expander and the compressor may be referred to as an expansion end and a supercharging end of the expansion supercharger, respectively, and the compressor at this time is often referred to as a supercharger. Wherein the expansion end and the pressure increasing end are mechanically connected in a suitable manner. By "mechanically coupled" is herein understood that a fixed or adjustable rotational speed relationship between these rotating components is achieved by mechanical means such as drive shafts, gears, belts, etc.
The "main compressor" is also referred to as a Main Air Compressor (MAC), which is a compressor as the name implies. The "main compressor" is a compressor that compresses all or a major portion of the feed air fed into the air separation plant, and is typically disposed before a purification device of the air separation plant that purifies the feed air. All or a major portion of the aforementioned feed air may be referred to as total feed gas. For example, in the MAC/BAC process, the main compressor typically compresses the total feed gas to a pressure comparable to the highest operating pressure of the rectification column system. The highest operating pressure of the rectification column system, i.e. the operating pressure of the higher pressure column. As another example, in HAP processes, the main compressor typically compresses the total feed gas to a pressure significantly higher than the highest operating pressure of the rectification column system. The main compressor is typically a compressor driven by external energy.
A "rectifying column system" is used to separate feed air into air products of various composition. The rectifying column system includes a rectifying column for separating air into various gaseous products or liquid products having different purities of components, such as nitrogen products (GAN), liquid nitrogen products (LIN), oxygen products (GOX), liquid oxygen products (LOX), etc., by using a cryogenic distillation technique. The rectification column system may take the form of a single column or a plurality of columns, typically, for example, a double column. In rectifying column systems in the form of multiple columns, there is also typically provided a condensing evaporator which exchanges heat between the streams of the two columns with each other.
The "main heat exchanger" is used to cool feed air, e.g., warm compressed air and one or more cold streams, or a low temperature liquid air product and one or more warm streams, upon indirect heat exchange with a return stream from a rectification column system of an air separation plant. The main heat exchanger may be formed by a single heat exchanger section or by a plurality of heat exchanger sections connected in parallel and/or in series. Each heat exchanger section is for example constituted by more than one plate heat exchanger block. The plate heat exchanger blocks may have channels separated from each other and having heat exchanging surfaces, through which different streams flow, thereby cooling or heating, respectively. Typically, the primary heat exchanger may be an aluminum brazed plate fin heat exchanger (BAHX). By "fully cooled" is meant that the cooled stream enters the main heat exchanger at the hot end and is then cooled to the cold end temperature of the main heat exchanger, i.e., the cooled stream exits the cold end of the main heat exchanger. By "partially cooled" is meant that the cooled stream is cooled to an intermediate temperature between the hot side temperature and the cold side temperature of the main heat exchanger, i.e. the cooled stream exits from an intermediate location between the hot side and the cold side of the main heat exchanger. Similarly, "fully heated" means that the heated stream exits the hot side of the main heat exchanger and is heated to a hot side temperature. And "partially heated" means that the heated stream exits an intermediate location in the main heat exchanger and is heated to an intermediate temperature.
Fig. 2 shows the air separation apparatus 10a as a comparative example. In comparison with the air separation apparatus 10a in the comparative example of fig. 2, the air separation apparatus 10 further includes an additional piping 83 and an additional expander 3. In fig. 2 and 1, the same or similar elements are given the same or similar reference numerals to omit partial description, so that the overall description is more concise.
It will be understood that "upstream" and "downstream" will be used herein to describe relative orientations, with respect to the direction of flow of the fluid in the corresponding conduit. The corresponding stream flows to a relatively upstream location and then to a relatively downstream location, and therefore, will sometimes be referred to herein as "upstream" and "downstream" as "downstream".
It is also to be understood that the terms "conduit," "pipe section," and the like are used herein to refer to a line through which a stream flows and are not intended to limit the physical form of the corresponding elements. Taking a "pipeline" as an example, a pipeline may refer to a segment of a complete pipeline. The pipeline can also be a combination of a plurality of pipelines which are connected in sequence. The multiple lines may be connected by pipe joints or by other piping elements such as valves. The space in the pipe connection or other pipe element through which the flow passes can also be considered part of the pipe. For example, in fig. 2, taking the feed line 81 as an example, the feed line 81 may essentially comprise a total feed line 810 located before the location Z31, or may comprise two branch feed lines 811, 812 branching downstream of the location Z31. Taking the feed line 811 as an example, the feed line 811 includes not only pipe sections located upstream and downstream of the main heat exchanger 1, respectively, but also a space within the main heat exchanger 1 through which the corresponding stream passes.
The additional line 83 leads from the location Z31 of the feed line 83 before the main heat exchanger 1 and leads to the location Z32 of the reject line 82 between the main heat exchanger 1 and the rectification column system 2. That is, the upstream end of the additional line 83 is connected to a position Z31 of the feed line 83 upstream of the main heat exchanger 1, and the downstream end is connected to a position Z32 of the waste discharge line 82 between the main heat exchanger 1 and the rectifying column system 2. In other words, the additional line 83 may eventually merge a portion f3 of the total feed gas f0 in the feed line 83 into the exhaust gas W0 in the exhaust line 82. For the purpose of distinguishing from other subsequent portions, a portion f3 of the total feed gas f0 may be referred to herein as a third portion f3 of the total feed gas f0, and for convenience of description and understanding, may sometimes be referred to as a third portion of the feed gas f3 or an additional stream f3.
The additional expander 3 is disposed in the additional pipeline 83 such that the stream f3 in the additional pipeline 83 is expanded by the additional expander 3 and then sent to the waste discharge pipeline 82. That is, the additional line 83 may send the third portion of the feed gas f3 from a location Z31 of the feed line 83 upstream of the main heat exchanger 1 to the inlet of the additional expander 3, and then send the expanded cooled third portion of the feed gas f3 from the outlet of the additional expander 3 to the exhaust line 82.
It will be appreciated that where a stream is described herein as entering a first element and a second element in sequence, or where similar descriptions are used, that is merely indicative of the sequence in which the stream enters the first element and the second element, it is not excluded that the stream also passes through a third element between the first element and the second element, nor that the stream also passes through the third element before the first element or after the second element. For example, describing the passage of the additional line 83 from the location Z31 to the location Z32 does not exclude that the above-mentioned additional line 83 also passes through the additional expander 3 between the location Z31 and the location Z32, nor that an additional compressor 4, the main heat exchanger 1, etc., which will be described later, are also passed before the additional expander 3.
It will be appreciated that, as previously mentioned, the description of individual components or processes merely indicates that the stream has been passed through or sequentially through the individual components or processes described above, and that other components or processes before, after, or between are not precluded. For example, the feed stream s0 may be dried, purified, etc., using a particular process or apparatus, e.g., by an absorber, filter, additional heat exchanger, etc., prior to being fed to the distillation column 81.
In comparison with the air separation plant 10a of fig. 2 as a comparative example, with the above-described air separation plant 10, under low-production conditions, the main compressor 61 can be fed with the total feed gas f0 having a mass flow exceeding the demand (corresponding to the sum of the mass flows of the feed gases f1 and f 2), and the excess portion of the feed gas f3 is led out through the additional line 83 without being sent to the rectifying column system 2. Thus, a large mass flow of the total feed gas f0 can be maintained through the main compressor 61 without causing a surge or other failure. Wherein the mass flow of the total feed gas f0 through the main compressor 61 may be made greater than or equal to the minimum mass flow that the main compressor 61 can withstand, which may be determined from the actual performance of the main compressor 61.
Further, in the above-described air separation plant 10, the part of the feed gas f3 in the additional line 83 is subjected to expansion refrigeration and then sent to the main heat exchanger 1a to absorb heat and vaporize, whereby the other part of the feed gas (in fig. 1, the feed gas f1, f 8) as a feed stream can be supplied with cold. That is, with the above arrangement, the third portion of the feed gas f3, which is larger than the actual demand, can supply cold to the rectifying column system 2, and thus more liquid products, more specifically, more liquid products, can be produced. In particular, "more liquid product" essentially refers to a higher yield of liquid product, which after all comes out of the mass flow of the feed stream (i.e., the feed to the rectification column system 2) to speak of a yield of liquid product being inadequate. It will be appreciated that users are generally particularly willing to access more liquid product because the liquid product is easy to store and expensive.
Further, in the above-described air separation plant 10, the third portion of the feed gas f3 in the additional line 83 is introduced into the exhaust gas W0, flows through the exhaust line 83, and is fed to the main heat exchanger 1a together with the exhaust gas W0. Thus, there is no need to additionally design a channel in the main heat exchanger 1a for the third portion of the feed gas f3 to circulate. Therefore, the structure of the main heat exchanger 1a does not need to be modified, and the cost can be remarkably reduced.
In addition, in the above-described air separation plant 10, there may be more of the portion of the feed gas that separates liquid products, such as liquid oxygen products. Therefore, in essence, even if only the amounts of the first portion of feed gas f1 and the second portion of feed gas f2 fed to the rectifying column system 2 are considered, the amount of this portion of feed gas can be higher than that required for the comparative example, which is little or not converted into a liquid product without the improvement of design, and thus the minimum mass flow rate that can be tolerated by the main compressor 61 can be more easily achieved.
In fig. 1, the air separation apparatus 10 may further comprise an adjusting device 51. The adjusting device 51 serves to adjust the mass flow of the stream f3 flowing from the feed line 81 to the additional line 83. For example, the regulating device 51 may be a regulating valve provided in the additional line 83, for example, which can regulate the mass flow of the stream f3 to zero.
In fig. 1, the air separation plant 10 may also comprise an additional compressor 4. The additional compressor 4 may be disposed in the additional line 83 upstream of the additional expander 3 such that the stream f3 in the additional line 83 is pressurized via the additional compressor 4 before entering the additional expander 3 for expansion. The expansion ratio of the additional expander 3 can be increased by increasing the pressure of the third portion of the feed gas f3 compressed by the additional compressor 4. Moreover, the volumetric flow rate of the third portion of the feed gas f3 compressed by the additional compressor 4 becomes smaller and can more easily enter the additional expander 3.
In fig. 1, the additional line 83 may reach the additional expander 3 downstream of the additional compressor 4 via the first location Z11 and the second location Z12 of the main heat exchanger 1 in sequence. Wherein the first bit Z11 is a hotter position relative to the second bit Z12. That is, the additional flow f3 in the additional line 83 passes through the main heat exchanger 1 from the first position Z11 to the second position Z12 and from the hotter flow to the colder flow. In other words, the additional stream f3 is first charged into the additional compressor 4, then cooled in the main heat exchanger 1, and finally expanded in the additional expander 3. Further, in fig. 1, the first bit Z11 may be the warm end of the main heat exchanger 1. The second position Z12 may be an intermediate position of the main heat exchanger 1. In other words, in fig. 1, the additional stream f3 is partially cooled by the main heat exchanger 1. The additional expander 3 is more efficient when the additional stream f3 at a lower temperature after cooling by the main heat exchanger 1 is expanded by the additional expander 3. Moreover, the additional stream f3 after cooling by the main heat exchanger 1 can easily reach a lower temperature after expansion by the additional expander 3, so as not to differ much from the temperature of the exhaust gas W0.
As shown in fig. 1, the third portion of the feed gas f3 after passing through the additional compressor 4 may be cooled by an after cooler 52. That is, the aftercooler 52 is disposed downstream of the additional compressor 4 and upstream of the additional expander 3, more precisely, upstream of the main heat exchanger 1, which will be mentioned later. In this way, more cooling may be provided by the aftercooler 52.
The "aftercooler" is used to cool the high temperature gas at the compressor outlet to below 40 ℃. Under certain conditions, the aftercooler may also help condense large amounts of water vapor and spoiled oil mist into liquid droplets and oil droplets for their removal. Typically, the aftercooler is a water-cooled aftercooler using cooling water at a lower temperature. The structure of the aftercooler may be, for example, a tube stack, with cooling water running through it.
In fig. 1, the additional compressor 4 and the additional expander 3 may be a boost end and an expansion end, respectively, mechanically connected in the expansion-supercharger 30. That is, the work of expansion of the additional stream f3 in the downstream additional expander 3 is directly converted into work of pressurizing the additional stream f3 in the upstream additional compressor 4. The additional compressor 4 at this time is often referred to as a supercharger.
With reference to fig. 1, the present invention also provides a space division method M0. The space division method M0 uses the space division apparatus 10. In essence, it can also be considered that the air separation apparatus 10 operates by using the air separation method M0.
The air separation method M0 includes feeding at least a part of the total feed gas f0 (the branched feed gases f4, f8 in the first portion f1 and the second portion f 2) from the main compressor 61 of the air separation apparatus 10 to the rectifying column system 2 via the main heat exchanger 1 as a feed stream of the rectifying column system 2. The air separation method M0 includes discharging the off-gas W0 from the rectifying column system 2 via the main heat exchanger 1.
The air separation method M0 further comprises, under predetermined conditions, withdrawing a portion (third portion f 3) from the total feed gas f0 as an additional stream f3 before the main heat exchanger 1 and letting the additional stream f3, after expansion treatment, to sink into the offgas W0 at a location Z32 between the main heat exchanger 1 and the rectifying column system 2.
In the above-mentioned air separation method M0, under the above-mentioned predetermined working conditions, the third portion of the feed gas f3 may be branched off from the total feed gas f0 in addition to the first portion of the feed gas f1 and the second portion of the feed gas f 2. The third portion of the feed gas f3 is introduced into the offgas W0 after the expansion treatment, and thus additional cold can be provided when it is vaporized together with the offgas W0 through the main heat exchanger 1, and thus the yield or production of liquid products can be improved. The predetermined operating conditions herein may correspond to the aforementioned low-yield operating conditions.
In another condition, the total feed gas f0 is split into only the first portion of feed gas f1 and the second portion of feed gas f2, and the third portion of feed gas f3 is not drawn out any more, and less cold is supplied to the system at this time, so that the yield of liquid products is low. The other condition here corresponds to the aforementioned design condition. It follows that, under design conditions, the additional line 83 and some components thereon, such as the additional expander 3, the additional compressor 4, etc., are essentially inactive, similar to vanishing. The additional expander 3 and the additional compressor 4 may be a low-pressure air expander, a low-pressure air compressor, or the like.
In fig. 1, the additional stream f3 may be subjected to a pressure boosting treatment prior to the expansion treatment described above in the space division method M0. That is, the additional stream f3 is pressurized and then expanded.
In fig. 1, in the space division method M0, the additional stream f3 may be cooled via the main heat exchanger 1a between the foregoing pressurization treatment and the foregoing expansion treatment. That is, the additional stream f3 is first subjected to a pressure increasing treatment, then cooled by the main heat exchanger 1a, and finally subjected to the aforementioned expansion treatment.
In the space division method M0, the additional stream f3 may be taken in from the warm end Z11 of the main heat exchanger 1a and taken out from the intermediate position Z12 of the main heat exchanger 1a when the additional stream f3 is cooled via the main heat exchanger 1 a. In other words, the additional stream f3 is partially cooled via the main heat exchanger 1 a.
In the space division method M0, the additional stream f3 may be cooled first via the aftercooler 52 and then via the main heat exchanger 1a after the foregoing supercharging. That is, after being pressurized by the additional compressor 4, the third portion of the feed gas f3 is primarily cooled by the aftercooler 52 and then further cooled by the main heat exchanger 1 a.
The pressure and temperature of the additional stream f3 after the expansion process described above can be reduced to a pressure and temperature comparable to that of the exhaust gas W0. I.e. such that the pressure, temperature of the additional stream f3 matches the pressure, temperature of the exhaust gas W0 to be led into it. The term "equivalent" here does not require a complete equality in the mathematical sense, but a certain degree of difference can be tolerated. For example, the temperature of the additional stream f3 and the exhaust gas W0 differ by within 20 ℃, preferably within 5 ℃ or even within 2 ℃; the pressure difference between the additional stream f3 and the exhaust gas W0 is within 0.1bar, preferably 0.01bar.
In the space division process M0, the ratio of the mass flow rate of the additional stream f3 to the mass flow rate of the total feed gas f0 can be made to be 5% to 20%, for example 7%. That is, under the aforementioned predetermined conditions, the third portion of the feed gas f3 accounts for 5% to 20% of the total feed gas f 0. The ratio of the mass flow of the feed stream (i.e., feed gases f1, f4, f 8) to the mass flow of the other conditions of the rectifying column system 2 under the aforementioned predetermined conditions is 40% to 60%, for example, 50%. It will be appreciated that "other operating conditions" are intended to be other than the predetermined operating conditions described above. For the case where the predetermined condition is a low-yield condition, the other condition is, for example, a design condition. It is understood that unless specifically stated otherwise, all ranges indicated herein include the endpoints.
An exemplary flow of the air separation apparatus 10 is described in detail below in conjunction with fig. 1. In fig. 1, the air separation plant 10 comprises two main heat exchangers 1. The main heat exchanger 1a may for example heat and vaporise a low pressure product gas, often referred to as a low pressure heat exchanger, while the main heat exchanger 1b may for example heat and vaporise a high pressure product gas, often referred to as a high pressure heat exchanger. Constructing the main heat exchanger 1 as a separate low pressure heat exchanger and high pressure heat exchanger may save manufacturing costs of the entire main heat exchange unit.
Feed line 81 may include feed lines 810, 811, 812, 813, 814, 815, 816, 817, 818, etc., for ease of description. It will be appreciated that when describing pressure herein, natural pressure losses are generally not considered. If the pressure difference between the respective locations is not greater than the natural line loss caused by the pressure loss in the piping, heat exchanger, cooler, adsorber, ordinary regulating valve (non-throttle valve), etc., the pressure is considered to be "equal" here even if the magnitude of such natural line loss is not small. For example, the second portion of feed gas f2 prior to recompression 62 and the first portion of feed gas f1 prior to rectification column system 2 are both described as being at first pressure P1. However, in practice, the pressure drop actually experienced by the first portion of feed gas f1 and the second portion of feed gas f2 is not substantially the same, as the lines flowing through are not the same, e.g. the pressure of the two may be + -1%, 5%, 10%, 20% or even 50% of the average. Conversely, the pressure of the stream downstream of certain process steps is described as "below" or "above" the pressure upstream of these process steps only if the corresponding pressure difference is higher than the natural line loss, in particular by pressurization by at least one compression stage or purposeful depressurization by at least one throttle valve and/or at least one expander. The above applies analogously to the description of the temperature. Further, in this case, the respective pressures and temperatures may be within a range of disjoint or within a range of overlapping each other. In particular, the pressure comprises, for example, an unavoidable or expected pressure drop and the temperature comprises, for example, an unavoidable or expected temperature drop.
In fig. 1, the MAC/BAC method is employed, and the air separation plant 10 includes a recompressor 62 in addition to the main compressor 61. The recompressor 62 further compresses at least a portion of the total feed gas f0 that has been compressed once by the main compressor 61 to a higher pressure, also referred to as BAC. In fig. 1, the main compressor 61 and the recompressor 62 are both compressors driven by external energy, and are the booster ends of the non-expansion booster.
It will be appreciated that the feed gas may be in a liquid state, a gas-liquid mixture state, etc. at some locations after various treatments. It is contemplated herein that the various treatments do not cause a change in the composition of the respective streams and, therefore, are sometimes still referred to as gases. For example, the third portion of the feed gas f3 passing through the throttle valve 53 is referred to as gas, but is substantially in a gas-liquid mixture.
After being compressed by the main compressor 61, the total feed gas f0 in the feed line 810, for example, atmospheric ambient air, reaches a first pressure P1 corresponding to the operating pressure of the higher pressure column 21. The temperature of the stream is likely to change in response to the pressure change, and therefore, when the stream is at a predetermined pressure after a certain treatment in some of the descriptions, the stream is necessarily also at a certain temperature in response thereto.
The feed line 810 branches downstream into feed lines 811, 812. The total feed gas f0 is divided into a first portion f1 (also referred to as first portion feed gas f 1), a second portion f2 (also referred to as second portion feed gas f 2), and a third portion f3 (also referred to as third portion feed gas f 3). The first portion of the feed gas f1 passes through feed line 811 to main heat exchanger 1a for cooling and enters rectifying column system 2.
The rectifying column system 2 includes a higher pressure column 21, a lower pressure column 22, and a main condensing evaporator 23 provided between the higher pressure column 21 and the lower pressure column 22. A first portion of feed gas f1 may enter the lower position of higher pressure column 21 of rectifying column system 2 via feed line 811.
After being compressed, for example, in part, by the recompressor 62, a portion f3 of the second partial feed gas f2 (also referred to as the first branched feed gas f 8) reaches the second pressure P2. The second pressure P2 is greater than the first pressure P1.
After partial compression by the recompressor 62, a portion f3 of the second partial feed gas f2 (also referred to as the first branched feed gas f 8) reaches a second pressure P2. After the first branched feed gas f8 has entered the main heat exchanger 1a and been completely cooled, it is continued to be fed via feed line 813 to the bottom position H3 of the higher pressure column 21. As will be described later, after the main heat exchanger 1a, the first branched feed gas f8 in the feed line 813 is converged into the downstream feed line 818 together with the first branched feed gas f5, and thus enters the higher pressure column 21 via the feed line 818.
In fig. 1, the feed line 813 is provided with a throttle valve 53 after the main heat exchanger 1 a. That is, the first branched feed gas f8 is expanded via the throttle valve 53 and then depressurized and cooled.
In fig. 1, after having been compressed, for example, completely, by means of a recompressor, a further portion f4 of the second partial feed gas f2 (also referred to as second branched feed gas f 4) reaches a third pressure P3. The third pressure P3 is greater than the second pressure P2. For example, the recompressor may include multiple compression stages, the first branched feed gas f8 may be compressed only through the previous compression stage or stages (not all compression stages) of the recompressor, and the second branched feed gas f4 may be compressed through all compression stages of the recompressor.
Also shown in fig. 1, similar to the first branched feed gas f8, a further portion fi of the second branched feed gas f2 (also referred to as third branched feed gas fi) is also drawn off by partial compression by a recompressor. In fig. 1, the third branched feed gas fi after being compressed by the recompressor also reaches the second pressure P2, temperature T2. The third branch feed gas fi may be a meter gas.
With continued reference to fig. 1, the second branched feed gas f4 in feed line 814 branches into feed lines 815 and 816 at downstream location Z56. That is, the second branch feed gas f4 in the feed line 814 splits downstream into a first branch feed gas f5 and a second branch feed gas f6, in other words, the first branch feed gas f5 and the second branch feed gas f6 are each part of the second branch feed gas f 4.
The feed line 815 may lead to the higher pressure column 21 of the rectification column system 2 via the main heat exchanger 1b (from a hotter to a colder position of the main heat exchanger 1 b). That is, the first branch feed gas f5 in feed line 815 enters the main heat exchanger 1b, e.g., is fully cooled, and is then fed to the higher pressure column 21 of the rectification column system 2, e.g., at a lower position H12.
The feed line 815 may pass through the compressor 63 before passing through the main heat exchanger 1 b. That is, the first leg feed gas f5 in feed line 815 may be compressed by compressor 63 and thus pressurized to pressure P31 and warmed to temperature T31. Then, the first branch feed gas f5 at the pressure P31 and the temperature T31 is completely cooled by the main heat exchanger 1b, and is cooled down to the temperature T32.
After passing through the main heat exchanger 1b, the feed line 815 may pass through the expander 72 before reaching the rectifying column system 2. That is, the first branch feed gas f5 in the feed line 815, after having been cooled by the main heat exchanger 1b, enters the expander 72 to expand, thereby lowering the pressure to the pressure P33, and lowering the temperature to the temperature T33. As previously mentioned, feed line 815, after passing through expander 72, merges with feed line 813 through throttle valve 53 to form a downstream feed line 817. That is, the first branch feed gas f5 in feed line 815 merges with the first branch feed gas f8 in feed line 813 to be fed to higher pressure column 21 at a common location H12. In fig. 1, the expander 72 is not an expansion end of the expansion supercharger, but is externally supplied with energy, and may be connected to a generator, for example.
Feed line 816 may lead to higher pressure column 21 of rectifying column system 2 via main heat exchanger 1b (from a hotter to a colder location of main heat exchanger 1 b). That is, the second branch feed gas f6 in feed line 816 enters main heat exchanger 1b, e.g., partially cooled, and is then fed to higher pressure column 21 of rectifying column system 2, e.g., at lower location H11.
After passing through the main heat exchanger 1b, the feed line 816 may pass through the expander 71 before reaching the rectifying column system 2. That is, the second branch feed gas f6 in feed line 816, after being cooled by main heat exchanger 1b, enters expander 71 for expansion, thereby reducing pressure to pressure P62 and reducing temperature to temperature T62. The feed line 816 merges with the feed line 811 through the main heat exchanger 1a after passing through the expander 71. That is, the second branch feed gas f6 in feed line 816 merges with the first portion of feed gas f1 in feed line 811 to be fed to higher pressure column 21 at location H1 1. In fig. 1, position H11 is lower than position H12. In fig. 1, the expander 71 and the compressor 63 may be an expansion end and a boost end of an expansion booster, respectively. This can make full use of expansion work, saving energy consumption.
In fig. 1, the rectifying column system 2 may include a higher pressure column 21, a lower pressure column 22, and a main condensing evaporator 23. It will be appreciated that the pressure in higher pressure column 21 and lower pressure column 22 are relatively high and low. For example, in practice, in some projects, higher pressure column 21 is also referred to as a medium pressure column, and the operating pressure of the medium pressure column is higher than that of lower pressure column 22.
The feed line 3 finally feeds at least part of the total feed gas f0 to the higher pressure column 21 as a feed stream to the rectification column system 2 at lower positions H11, H12 by branching, merging or the like.
A waste line 82 leads from the lower pressure column 22 to the main heat exchanger 1a (from a colder to a hotter position). In other words, the off-gas W0 in the off-gas discharge line 82 is discharged from the low-pressure column 22 after being completely heated, for example, by the main heat exchanger 1 a. The exhaust gas W0 heated by the main heat exchanger 1a in the exhaust line 82 may be directly discharged to the atmosphere or may be led to another device for reuse. The other means may be, for example, a pre-cooling purification means of the air separation plant 10, which pre-cooling purification means may be arranged between the main compressor 61 and the recompressor 62, in particular after the main compressor 1 and before the branching of the main feed line 810 into the feed lines 811, 812.
In fig. 1, the waste line 82 also passes through a subcooler 91 (from a colder to a hotter) before being routed to the main heat exchanger 1 a. In other words, the exhaust gas W0 in the exhaust line 82 passes through the subcooler 91 for the first time, for example, for complete heating, and then passes through the main heat exchanger 1a for the second time after exiting the low pressure column 22. The location Z32 is located between the main heat exchanger 1a and the subcooler 91.
In fig. 1, between the subcooler 91 and the main heat exchanger 1a, further, between the subcooler 91 and the position Z32, the exhaust line 82 is further led out of a branch exhaust line 821, and a part of the exhaust gas W0 (denoted by W1 in the drawing) is led into the main heat exchanger 1b, and is heated to a gaseous state in the main heat exchanger 1 b. In addition, as shown in fig. 1, it is noted that, in the case where the waste discharge line 82 branches into a plurality of branches (two branches in fig. 1) at a downstream branching point, a position Z32 where the third portion of the feed gas f3 merges is disposed downstream of the branching point so as to merge into one of the plurality of branches, so that parameter matching is easily achieved. In addition, compared with an upstream main pipeline which is not branched, the pipe diameter of the branch pipe is smaller, and even if the pipe diameter change is caused by the convergence of the third part of feed gas f3, the pipe diameter is not too large.
Fig. 1 and 2 also show other exemplary lines involved in the rectifying column system 2. An exemplary configuration is described in further detail herein in connection with fig. 1.
Oxygen-enriched liquid f50 accumulated at the bottom of higher pressure column 21 may be fed from bottom position H0 to subcooler 91 for cooling and then fed to lower pressure column 22 at position H7 after throttling expansion via throttle valve 57. In fig. 1, between the throttle valve 71 and the subcooler 91, a portion of the liquid stream f501 is diverted from the oxygen-enriched liquid f50 and may be passed to the pseudo-argon column 24, and in particular, to the overhead condenser in the pseudo-argon column 24.
Under the distillation action of higher pressure column 21, nitrogen-rich stream f52 may be withdrawn from location H2 of higher pressure column 21. The nitrogen-rich stream f52 is cooled by the subcooler 91, throttled and expanded by the throttle valve 52, and then fed to the low-pressure column 22 at a position H91 as reflux.
Under the distillation of the higher pressure column 21 and the condensation of the main condensation evaporator 23, nitrogen-rich streams c1, c2 can be obtained at the top positions H31, H32 of the higher pressure column 21. Wherein the positions H31 and H32 may be located at substantially the same height. The nitrogen-rich stream c2 may be cooled via subcooler 91 and then throttled expanded via throttle valve 55 directly as a liquid nitrogen product (LIN), for example stored in a storage tank. The nitrogen-rich stream c1 may be split into two portions, a first portion of the nitrogen-rich stream c11 and a second portion of the nitrogen-rich stream c12. The first part of the nitrogen-rich stream c11 may be pumped under pressure via pump 65 to the main heat exchanger 1a and thus heated to a gaseous state, forming a low pressure nitrogen product (LPGAN), for example at a pressure of 9bara. The second portion of the nitrogen-rich stream c12 may be pressurized via pump 66, throttled expanded via throttle valve 56, and then fed to main heat exchanger 1a, thereby being heated to a gaseous state to form a high pressure nitrogen product at a higher pressure relative to the low pressure nitrogen product. In the embodiment of fig. 1, the high pressure nitrogen product is essentially 31bara, commonly referred to in the project as MPGAN. It is understood that bar is a unit of pressure, and bara means that the pressure is absolute.
The oxygen-enriched stream c3 may be withdrawn at position H4 of the main condensing evaporator 23 under the evaporating action of the main condensing evaporator 23. The oxygen-enriched stream c3 may be split into three portions, a first portion of the oxygen-enriched stream c31, a second portion of the oxygen-enriched stream c32, and a third portion of the oxygen-enriched stream c33. A first portion of the oxygen-enriched stream c31 may be pumped under pressure via pump 67 to main heat exchanger 1b and thus heated to a gaseous state to form a low pressure oxygen product (LPGOX), for example at a pressure of 14bara. The second portion of the oxygen-enriched stream c32 may be pressurized via pump 68 to a higher pressure relative to the previously described low pressure oxygen product and pumped into main heat exchanger 1b and thus heated to a gaseous state to form a high pressure oxygen product (HPGOX), for example at a pressure of 31bara. The third oxygen-enriched stream c33 may be cooled via subcooler 91 and then throttled to expand via throttle valve 54 directly as a liquid oxygen product (LOX).
In fig. 1, feed line 817, formed by the joining of feed lines 813, 815, also exits a branch line 818 at location Z17 before reaching rectifying column system 2 (specifically, location H12). Stream f18 (a portion of the stream after combining feed gas f3 and feed gas f 5) in branch line 818 is cooled by subcooler 91 and then throttled expanded by throttle valve 58 before being fed to lower pressure column 22 at location H8.
In FIG. 1, there is also shown an oxygen-enriched gas f71 exiting from the location H5 of the lower pressure column 22 and fed to the pseudo argon column 24, as well as a crude argon gas f72 produced from the pseudo argon column 24. The crude argon gas f72 from the pseudo argon column 24 is heated by the subcooler 91 and then enters the main heat exchanger 1b for heating.
Also shown in FIG. 1 are an oxygen-enriched blowdown (purge) stream f61 and an oxygen-enriched stream f62 fed from pseudo argon column 24 to low pressure column 22 at locations H61 and H62. Wherein the oxygen-rich blowdown stream f61 may flow out of the bottom of the top condenser in the pseudo argon column 24.
Referring to fig. 1, in higher pressure column 21, from low to high, positions H0, H11, H12, H2, H31 are in this order, wherein positions H31 and H32 are at substantially the same height. In the low pressure column 22, positions H5, H61, H62, H7, H8, H9, and H10 are in this order from low to high.
Specific examples of applying the above-described air separation apparatus 10 and air separation method M0 are provided below. The total feed gas f0 in feed line 810 is at atmospheric temperature prior to compression by main compressor 61. For example, the temperature is 32℃and the pressure is 1bara. The operating pressures of lower pressure column 22 and higher pressure column 21 were 1.2bara and 5.5bara, respectively.
In design mode, the total feed gas f0 mass flow in feed line 810 is 213500Nm3/h. The mass flow of the feed stream (f1+f4+f8) of the rectification column system 2 was 209500Nm3/h. After compression by the main compressor 61, the total feed gas f0 reaches 5.6bara, 100 ℃. After the total feed gas f0 was split, the mass flow rates of the first part feed gas f1 and the second part feed gas f2 were 54400Nm3/h and 159100Nm3/h, respectively. That is, by means of the adjusting means 5, the mass flow of the third portion of feed gas f3 can be made zero. After the second partial feed gas f2 was split, the mass flow rates of the first branched feed gas f8, the second branched feed gas f4 and the third branched feed gas fi were 24000Nm3/h, 131100Nm3/h and 4000Nm3/h, respectively.
In the low-yield mode, the total feed gas f0 in the feed line 810 has a mass flow rate of 161900Nm3/h. After compression by the main compressor 61, the total feed gas f0 reaches 5.5bara, 100 ℃. After the total feed gas f0 was split, the mass flow rates of the first part feed gas f1 and the second part feed gas f2 were 7600Nm3/h and 140500Nm3/h, respectively. That is, the mass flow rate of the third portion of the feed gas f3 can be made 13800Nm3/h by the adjusting means 5. After the second partial feed gas f2 was split, the mass flow rates of the first branched feed gas f8, the second branched feed gas f4 and the third branched feed gas fi were 12000Nm3/h, 124500Nm3/h and 4000Nm3/h, respectively. Thus, the mass flow rate of the feed stream (f1+f4+f8) of the rectifying column system 2 was 144100Nm3/h.
After compression by the additional compressor 4, the third portion of feed gas f3 is boosted and warmed to 9.2bara, 80 ℃. After cooling by aftercooler 52, the third portion of feed gas f3 is cooled to 36 ℃. After the partial cooling by the main heat exchanger 1a, the third portion of the feed gas f3 is cooled to-90 ℃. After expansion by the additional expander 3, the third part of the feed gas f3 is depressurized and cooled to 1bara, -165 ℃. Wherein the dirty nitrogen W0 is 1bara, -177 ℃ before entering the main heat exchanger 1 a.
Table 1 below lists the comparison of the parameters produced in the two modes in the specific example described above.
TABLE 1
In the above example, the mass flow rate of HPGOX is not reduced in the low-yield mode compared to the design mode. This can present a significant challenge to the varying loads of all units in the air separation plant.
Table 1 above shows that in the low yield mode, the yield of liquid oxygen product LOX and even liquid nitrogen product LIN can be significantly improved. In practice, the control system may be used to shift the yields of liquid oxygen and liquid nitrogen products in the low-yield mode.
Each aspect or embodiment defined herein may be combined with any other aspect or embodiment unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.
The preferred embodiments of the present invention are described in this specification, which are intended to be illustrative of the technical solution of the present invention and not limiting. All technical solutions that can be obtained by logic analysis, reasoning or limited experiments according to the inventive concept by those skilled in the art shall be within the scope of the present invention.

Claims (13)

1. An air separation plant comprising a feed conduit for feeding at least a portion of a total feed gas from a main compressor to a rectifying column system via a main heat exchanger and a waste discharge conduit for discharging waste gas from the rectifying column system via the main heat exchanger, characterized in that the air separation plant further comprises:
an additional line leading from a location of the feed line prior to the main heat exchanger and leading to a location of the waste discharge line between the main heat exchanger and the rectifying column system; and
the additional expander is arranged on the additional pipeline, so that the flow in the additional pipeline is sent into the waste discharge pipeline after being expanded by the additional expander.
2. The air separation apparatus of claim 1, further comprising:
and adjusting means for adjusting the mass flow of the stream flowing from the feed line to the additional line.
3. The air separation apparatus of claim 1, further comprising:
and an additional compressor arranged on the additional pipeline and upstream of the additional expander, so that the flow in the additional pipeline enters the additional expander for expansion after being pressurized by the additional compressor.
4. A space division apparatus according to claim 3 wherein the additional line reaches the additional expander downstream of the additional compressor via a first location and a second location of the main heat exchanger in sequence, wherein the first location is a hotter location relative to the second location.
5. The air separation apparatus of claim 4, further comprising:
an aftercooler is disposed in the additional line between the additional compressor and the main heat exchanger.
6. The air separation plant of claim 4 wherein the first location is a warm end of the main heat exchanger; and/or
The second location is an intermediate location of the primary heat exchanger.
7. A space division apparatus according to claim 3, wherein the additional compressor and the additional expander are a boost end and an expansion end, respectively, of a mechanical connection in an expansion booster.
8. An air separation method using an air separation plant, the air separation method comprising feeding at least a portion of a total feed gas from a main compressor of the air separation plant to a rectifying column system via a main heat exchanger as a feed stream to the rectifying column system and discharging an exhaust gas from the rectifying column system via the main heat exchanger, characterized in that the air separation method further comprises:
Under predetermined conditions, a portion is withdrawn from the total feed gas as an additional stream prior to the main heat exchanger and the additional stream is passed into the offgas via an expansion process at a location between the main heat exchanger and the rectification column system.
9. The air separation process of claim 8 wherein said additional stream is subjected to a pressure boost treatment prior to said expansion treatment.
10. The air separation process of claim 9 wherein said additional stream is cooled via said main heat exchanger between passing through said pressure boost treatment and said expansion treatment.
11. The air separation process of claim 10 wherein said additional stream is cooled after said pressure boost treatment by first passing through an aftercooler and then passing through said main heat exchanger.
12. The air separation process of claim 10, wherein the additional stream is taken in from the warm end of the main heat exchanger and taken from an intermediate location of the main heat exchanger as the additional stream is cooled via the main heat exchanger;
so that after the expansion process the pressure and temperature of the additional stream is reduced to a pressure and temperature comparable to the exhaust gas.
13. The air separation process according to any one of claims 8 to 12, wherein the ratio of the mass flow of the additional stream to the mass flow of the total feed gas is made to be 5% to 20%;
the ratio of the mass flow rate of the raw material flow of the rectifying tower system under the preset working condition to the mass flow rate under other working conditions is 40% -60%.
CN202310450033.5A 2023-04-24 2023-04-24 Air separation device and air separation method Pending CN116538763A (en)

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