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
  • F25J3/04763—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
  • 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
  • F25J3/04278—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using external refrigeration units, e.g. closed mechanical or regenerative refrigeration units
• • 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
  • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
  • F25J3/0429—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of feed air, e.g. used as waste or product air or expanded into an auxiliary column
  • F25J3/04303—Lachmann expansion, i.e. expanded into oxygen producing or low pressure column
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
  • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
  • F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
  • F25J3/04381—Details relating to the work expansion, e.g. process parameter etc. using work extraction by mechanical coupling of compression and expansion so-called companders
• • 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
  • F25J3/04406—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
  • F25J3/04642—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
  • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
  • F25J3/04969—Retrofitting or revamping of an existing air fractionation unit
• • 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
  • F25J2200/00—Processes or apparatus using separation by rectification
  • F25J2200/20—Processes or apparatus using separation by rectification in an elevated pressure multiple column system wherein the lowest pressure column is at a pressure well above the minimum pressure needed to overcome pressure drop to reject the products to atmosphere
• • 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
  • F25J2215/40—Air or oxygen enriched air, i.e. generally less than 30mol% of 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
  • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
  • F25J2230/20—Integrated compressor and process expander; Gear box arrangement; Multiple compressors on a common shaft
• • 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

Definitions

• the present invention relates to a method and system for cryogenic air separation involving production of liquid products by using an integrated refrigeration system comprising a primary refrigeration circuit and an auxiliary refrigeration circuit. More particularly, the present invention relates to an auxiliary refrigeration circuit that can be easily tied-in to an existing cryogenic air separation plant and its existing refrigeration system.
• Oxygen, nitrogen and argon are separated from air through cryogenic rectification in an air separation plant.
• gaseous and/or liquid products are produced for on-site customers or pipeline customers, with any excess products often converted to merchant liquid products for nearby customers.
• the on-site or pipeline customer demand for gaseous products such as gaseous oxygen or gaseous nitrogen, may decrease over time either on a long-term basis or perhaps on a more temporary or mid-term basis.
• the cryogenic air separation plant may be operated so as to vent some of the unneeded gaseous product which is economically inefficient as such venting ultimately wastes the power/energy costs used to produce the vented gaseous products.
• the air separation plant may be operated in a turn-down mode which produces less gaseous product but at less than full plant capacity and separation efficiency.
• a third option is to adjust the product slate of the cryogenic air separation plant to produce more liquid products in lieu of the lowered gaseous product requirement.
• the conventional or main source of refrigeration for a cryogenic rectification plant is typically supplied by a turbine-based refrigeration system capable of expanding part of the feed air stream or a waste stream to generate a refrigeration stream that is then introduced into the main heat exchanger or the distillation column system of the cryogenic air separation plant.
• Supplemental refrigeration required to produce additional liquid products may be supplied with an additional turbine-based refrigeration source.
• additional turbine-based refrigeration systems involve additional capital costs and are often not optimized or fully integrated with the main source of refrigeration for a cryogenic air separation plant.
• the present invention may be characterized as a method of separating air in an air separation unit.
• the air separation unit preferably comprises a main heat exchanger configured to cool a compressed and purified feed air stream to a temperature suitable for the rectification and a distillation column system configured to rectify the compressed, purified and cooled air stream to produce at least one liquid product stream.
• the present method comprises the steps of: (a) compressing and purifying a feed air stream to produce the compressed and purified feed air stream; (b) diverting a first portion of the compressed and purified feed air stream to a first refrigeration circuit configured to produce a first cooled refrigeration stream; (c) diverting a second portion of the compressed and purified feed air stream to the main heat exchanger to cool the second portion of the compressed and purified feed air stream and wherein the cooled second portion of the compressed and purified feed air stream is subsequently directed to the higher pressure column of the distillation column system; (d) diverting a third portion of the compressed and purified feed air stream to a booster air compression circuit configured to produce a further compressed feed air stream and wherein part of the further compressed feed air stream is directed to the main heat exchanger where the further compressed feed air stream is cooled to produce a liquid air stream that is directed to the distillation column system; (e) diverting a fraction of the further compressed feed air stream from the booster air compression circuit to an auxiliary refrigeration circuit configured to produce
• the present invention may also be characterized as an air separation unit configured to produce at least one liquid product stream.
• the air separation unit comprises: (i) an incoming air compression and purification train configured to produce a compressed and purified feed air stream; (ii) a primary refrigeration circuit having a first turbo-expander, the primary refrigeration circuit operatively coupled to the incoming air compression and purification train and configured to receive a first portion of the compressed and purified feed air stream and expand the first portion of the compressed and purified feed air stream in the first turbo-expander to produce a first cooled refrigeration stream; (iii) a main heat exchanger operatively coupled to the incoming air compression and purification train and configured to receive a second portion of the compressed and purified feed air stream and to cool the second portion of the compressed and purified feed stream to a temperature suitable for the rectification of the compressed and purified feed air stream; (iv) a booster air compression circuit operatively coupled to the incoming air compression and purification train and the main heat exchanger,
• the first refrigeration circuit may include a compressor for further compressing the first portion of the compressed and purified feed air stream; a cooling means such as an aftercooler and/or main heat exchanger configured to cool the further compressed first portion of the compressed and purified feed air stream; and a first turbo-expander disposed within the first refrigeration circuit and configured to expand the further compressed first portion of the compressed and purified feed air stream to produce the first refrigeration stream.
• the auxiliary refrigeration circuit may also include an auxiliary compressor and cooling means.
• the diversion of the fraction of the further compressed feed air stream to the auxiliary refrigeration circuit preferably includes further includes diverting one or more fractions of the third portion of the compressed and purified feed air stream from one or more interstage locations of the plurality of compression stages to the auxiliary refrigeration circuit.
• One or more flow control valves are disposed between the booster air compression circuit and the second turbo- expander in the auxiliary refrigeration circuit to control the flow of the diverted one or more fractions and the inlet pressure to the second turbo-expander in the auxiliary refrigeration circuit.
• FIG. 1 is a schematic process flow diagram of a cryogenic air separation plant integrated with an add-on supplemental or auxiliary refrigeration circuit in accordance with the present invention.
• FIG. 2 is a schematic process flow diagram of a cryogenic air separation plant integrated with an alternate embodiment of the add-on supplemental or auxiliary refrigeration circuit also in accordance with the present invention.
• an air separation unit 10 generally includes an incoming air compression and purification train or circuit (not shown); a primary refrigeration circuit 20; a booster air compression train or circuit 30; a main heat exchanger 40; and a distillation column system 50.
• the incoming feed air is compressed in a multi-stage, intercooled, main air compressor arrangement to a pressure that can be between about 5 bar(a) and about 15 bar(a).
• This main air compressor arrangement may be an integrally geared compressor or a direct drive compressor arrangement.
• the compressed air feed is then purified in a pre-purification unit to remove high boiling contaminants from the incoming feed air.
• a pre-purification unit typically contains beds of alumina and/or molecular sieve operating in accordance with a temperature and/or pressure swing adsorption cycle in which moisture and other impurities, such as carbon dioxide, water vapor and hydrocarbons, are adsorbed.
• the compressed and purified feed air stream 12 is divided into a plurality of portions which are further compressed and/or cooled.
• the different portions of the compressed and purified air stream are then separated into oxygen-rich, nitrogen-rich, and argon-rich fractions in a plurality of distillation columns that comprise the distillation column system 50.
• the distillation column system 50 may include thermally linked higher pressure column 54 and lower pressure column 56, as well as an optional argon rectification column 58.
• portions of the compressed and purified feed air stream 12 may be further compressed in a booster air compression train or circuit 30 and/or cooled to temperatures suitable for rectification within a primary or main heat exchanger 40.
• the cooling is typically achieved using refrigeration from the various oxygen, nitrogen and/or argon streams produced by the air separation unit 10 as well as refrigeration generated by one or more refrigeration circuits often as a result of turbo-expansion of various air streams in an upper column turbine (UCT) arrangement, a lower column turbine (LCT) arrangement, and/or a warm recycle turbine (WRT) arrangement as known to persons skilled in the art.
• UCT upper column turbine
• LCDT lower column turbine
• WRT warm recycle turbine
• FIG. 1 an embodiment of the present invention is illustrated that includes a plurality of divided portions of the compressed and purified feed air stream.
• a first portion 13 of the compressed and purified feed air stream resulting from the compression and pre-purification of the incoming feed air, is diverted to a first or primary refrigeration circuit 20 shown as an upper column turbine (UCT) arrangement that is configured to produce a first cooled refrigeration stream 22.
• the first portion 13 of the compressed and purified feed air stream is further compressed in compressor 24 and cooled in an aftercooler 25 and/or main heat exchanger 40.
• the compressed and cooled (or partially cooled) stream is then expanded in the first turbo-expander 26 to produce the first refrigeration stream 22.
• a portion of the first refrigeration stream is directed to the lower pressure column while a second portion of the first refrigeration stream is diverted to the auxiliary or second refrigeration circuit 60 as described in more detail below.
• a second portion 15 of the compressed and purified feed air stream is directed or diverted to the main heat exchanger 40 to cool this portion of the compressed and purified feed air stream.
• the resulting cooled second portion 42 of the compressed and purified feed air stream is then directed to the higher pressure column 54 of the distillation column system 50 as generally known in the art and practiced in many cryogenic air separation units.
• a third portion 17 of the compressed and purified feed air stream is diverted to a booster air compression circuit 30 configured to produce a further compressed, high pressure feed air stream 32.
• the booster air compression circuit 30 employs a booster air compressor arrangement 33 having a plurality of compression stages with intercoolers and aftercoolers 31 and forms a high pressure air stream 32 that is fed to the main heat exchanger 40.
• the high pressure air stream forms a liquid phase or a dense fluid if its pressure exceeds the critical pressure after cooling in the main heat exchanger.
• This liquid air stream 34 is then split into two portions 35, 36, with a first portion 35 being directed through an expansion valve 37 and into the higher pressure column 54 of the distillation column system 50 and a second portion 36 is expanded through another expansion valve 38 and introduced into the lower pressure column 56 of distillation column system 50.
• a fraction 62A, 62B of the third portion 17 of the compressed and purified feed air stream is further diverted from the booster air compression circuit 30 to an auxiliary refrigeration circuit 60 configured to produce a second refrigeration stream 66.
• the auxiliary refrigeration circuit 60 preferably includes an auxiliary compressor 63, a second turbo-expander 64, and an auxiliary heat exchanger 65.
• This fraction 62A, 62B of the further compressed feed air stream from the booster air compression circuit 30 is diverted via one or more flow control valves 67 A, 67B, to the auxiliary compressor 63 where the diverted fraction stream is further compressed (as stream 61), optionally cooled or partially cooled and then expanded in a turbo-expander 64.
• the diverted fraction stream is then cooled in the auxiliary heat exchanger 65 via indirect heat exchange with one or more cooling streams, preferably a diverted portion of the first refrigeration stream 28, to produce the cooled second refrigeration stream 66 exiting the auxiliary heat exchanger 65 and a warmed stream 29.
• the cooled second refrigeration stream 66 is then combined with the cooled second portion 34 of the compressed and purified feed air stream and the resulting combined stream 68 is then directed to the higher pressure column 54 to impart another or second portion of the refrigeration required by the distillation column system 50.
• part of the first refrigeration stream 22 is preferably diverted as a cooling stream 28 to the auxiliary heat exchanger 65 where it cools the diverted fraction 62A, 62B of the further compressed feed air stream in the auxiliary refrigeration circuit 60.
• the remaining portion of the first refrigeration stream 22 is directed to the lower pressure column 56 to impart a portion of the refrigeration required by the distillation column system 50.
• the supplemental refrigeration created by the expansion of the first portion 13 of the compressed and purified air stream in the first or primary refrigeration circuit 20 is thus imparted partly to the lower pressure column 56 and partly to the auxiliary heat exchanger 65 thereby alleviating some of the cooling duty of the primary heat exchanger 40.
• the present embodiment also shows a fourth portion 19 of the compressed and purified feed air stream that may also be diverted from the incoming air purification and compression circuit (not shown) as a carrier fluid to the auxiliary heat exchanger 65 where it is cooled and subsequently directed to the higher pressure column 54 of the distillation column system 50 so as to capture the auxiliary refrigeration.
• this cooled fourth portion 69 of the compressed and purified feed air stream may be combined with the warmed second refrigeration stream 66 and/or the cooled second portion 42 of the compressed and purified feed air stream exiting the main heat exchanger 40 with the resulting combined stream 68 then directed to the higher pressure column 54.
• the first portion of the compressed and purified feed air stream directed to the primary refrigeration circuit represents roughly 8% to 20% of the incoming feed air stream. Of this first portion, 0% to 12% of the incoming feed air stream is diverted as the second portion to the auxiliary heat exchanger to balance the temperatures in the auxiliary heat exchanger. Varying the amount of diverted air from the first refrigeration circuit to the auxiliary refrigeration circuit enables the air separation unit to readily switch between a high gaseous product make cycle and a high liquid product make cycle.
• the third portion of the compressed and purified feed air stream represents roughly 25% to 32% of the incoming feed air stream with roughly 5% to 10% of the incoming feed air stream being diverted to the auxiliary refrigeration circuit.
• the second portion and fourth portion of the compressed and purified feed air stream combined represents the remainder roughly of the incoming feed air stream 48% to 67% of the incoming feed air stream.
• the exact split between the second portion and fourth portion of the compressed and purified feed air stream depends on the heat exchange duties in the main heat exchanger and auxiliary heat exchanger.
• the main heat exchanger 40 and auxiliary heat exchanger 65 are preferably a brazed aluminum plate-fin type heat exchanger.
• Such heat exchangers are advantageous due to their compact design, high heat transfer rates and their ability to process multiple streams. They are manufactured as fully brazed and welded pressure vessels.
• the brazing operation involves stacking corrugated fins, parting sheets and end bars to form a core matrix. The matrix is placed in a vacuum brazing oven where it is heated and held at brazing temperature in a clean vacuum environment.
• a heat exchanger comprising a single core may be sufficient.
• a heat exchanger may be constructed from several cores which may be connected in parallel or series.
• the turbo-expanders 26 and 64 are preferably linked with booster air compressors 24 and 63 respectively, either directly or by appropriate gearing.
• the turbo-expanders may also to be connected or operatively coupled to a generator.
• Such generator loaded turbo-expander arrangement allows the speed of the turbo-expander to be maintained constant even at very high or low loads. This arrangement is desirable in some applications because the speed of the turbo- expander would remain generally constant at the ideal efficiency across the entire operating envelope.
• the generator load may be connected to the turbo-expander by means of a high speed generator.
• the generator load may be connected to the turbo-expander by means of a high speed coupling connected to an internal or external gearbox and with a low speed coupling from the gearbox to the generator.
• the distillation column system 50 preferably includes a thermally linked higher pressure column 54 and lower pressure column 56 as well as an optional argon rectification column 58.
• vapor and liquid are counter- currently contacted in order to affect a gas/liquid mass-transfer based separation of the respective feed streams.
• Such columns will preferably employ structured packing or trays or combinations thereof.
• the higher pressure column 54 typically operates in the range from between about 20 bar(a) to about 60 bar(a) whereas the lower pressure column 56 typically operates at pressures between about 1.1 bar(a) to about 1.5 bar(a).
• the higher pressure column 54 and the lower pressure column 56 are linked in a heat transfer relationship such that a nitrogen-rich vapor column overhead, extracted from the top of higher pressure column as a stream 71, is condensed within a main condenser-reboiler 55 located in the base of lower pressure column 56 against boiling an oxygen-rich liquid column bottoms 72.
• the boiling of oxygen-rich liquid column bottoms 72 initiates the formation of an ascending vapor phase within lower pressure column 56.
• the condensation produces a liquid nitrogen containing stream 73 that is divided into streams 74 and 75 that reflux the higher pressure column 54 and the lower pressure column 56, respectively to initiate the formation of descending liquid phases in such columns. If liquid nitrogen product is required, stream 76 may also be recovered.
• Streams 34, 66, and 69 are introduced into the higher pressure column 54 along with the expanded liquid air stream 39 for rectification by contacting an ascending vapor phase of such mixture within a plurality of mass transfer contacting elements with a descending liquid phase that is initiated by reflux stream 74.
• a stream 79 representing a portion of the nitrogen-rich column overhead 78 may be directed to the main heat exchanger 40 to provide refrigeration to the feed air streams.
• a stream 101 of the crude liquid oxygen column bottoms 77 may be directed to the argon column 58 to as a reflux to aid in the recovery of argon product 93.
• a stream of the crude liquid oxygen column bottoms may be expanded in an expansion valve to the pressure at or near that of the lower pressure column and introduced into the lower pressure column for further rectification.
• Lower pressure column 56 is also provided with a plurality of mass transfer contacting elements that can be trays or structured packing or random packing or other known elements in the art of cryogenic air separation. As stated previously, the separation produces an oxygen-rich liquid 80 and a nitrogen-rich vapor column overhead 82 that is extracted as a nitrogen product stream 84. Additionally, a waste stream 85 is also extracted to control the purity of nitrogen product stream 84. Both nitrogen product stream 84 and waste stream 85 are passed through a subcooling unit 90 designed to subcool the reflux stream 75. A portion of the reflux stream may optionally be taken as a liquid product stream 76 and the remaining portion (shown as stream 75B) may be introduced into lower pressure column 56 after passing through expansion valve 99.
• a subcooling unit 90 designed to subcool the reflux stream 75.
• a portion of the reflux stream may optionally be taken as a liquid product stream 76 and the remaining portion (shown as stream 75B) may be introduced into lower pressure column 56 after passing through expansion valve 99.
• the warmed waste stream 95 may be used to regenerate the adsorbents within pre-purification unit.
• an oxygen-rich liquid stream 80 is extracted from the oxygen-rich liquid column bottoms 72 near the bottom of the lower pressure column 56.
• Oxygen-rich liquid stream 80 can be pumped by a pump 83 to form a pumped product stream as illustrated by pumped liquid oxygen stream 86.
• Part of the pumped liquid oxygen stream 86 can optionally be taken directly as a liquid oxygen product stream 88, with the remainder, namely stream 87, being directed to the main heat exchanger 40 where it is warmed and vaporized to produce a pressurized oxygen product stream 97.
• Pumped liquid oxygen stream 86 can be pressurized to above or below the critical pressure so that oxygen product stream 97 when discharged from main heat exchanger 40 will be a supercritical fluid. Alternatively, the pressurization of pumped liquid oxygen stream 86 could be lower to produce an oxygen product stream 97 in a vapor form.
• Fig. 2 differs from Fig. 1 in that all or a portion of the partially warmed, expanded working fluid 27 in the auxiliary refrigeration circuit 60 is recycled back to the first refrigeration circuit 20 at a location upstream of the first turbo-expander 26. In this manner, the working fluid 27 undergoes two stages of expansion in a serial arrangement.
• the turbo-expander 64 of the auxiliary refrigeration circuit 60 is arranged in series with the turbo-expander 26 of the first refrigeration circuit 20 with the resulted expanded working fluid being directed to the lower pressure column 56 and/or the auxiliary heat exchanger 65.
• auxiliary refrigeration circuit 60 Another difference between the embodiment shown in Fig. 2 and that of Fig. 1 is found in the auxiliary refrigeration circuit 60.
• all or a portion of the diverted fraction stream may optionally bypass the auxiliary compressor 63 and go directly to the second turbo-expander 64 and on to the auxiliary heat exchanger 65.
• flow control valve 67C When flow control valve 67C is open and flow control valve 67D is closed, the combined streams 62A and 62B are further compressed in auxiliary compressor 63, then expanded in second turbo-expander 64 and warmed in auxiliary heat exchanger 65.
• air separation unit 10 is capable of producing liquid products, namely, nitrogen-rich liquid stream 76 and liquid oxygen product stream 88.
• additional refrigeration is supplied by an add-on or auxiliary refrigeration circuit.
• the add-on refrigeration circuit is the auxiliary refrigeration circuit 60 that is preferably configured to be added to or bolted on the cryogenic air separation unit 10 after initial plant construction.
• the design of the auxiliary refrigeration circuit 60 is tailored for such late add-on or retrofit application and the tie-in points to the cryogenic air separation unit 10 are minimized.
• the first tie-in point 1 10 preferably occurs downstream of the main air compression train or circuit where the fourth portion 19 of the compressed and purified feed air stream 12 is diverted to the auxiliary or second refrigeration circuit, and more particularly, to the auxiliary heat exchanger 65.
• This first tie in point 110 is configured to provide the carrier fluid (i.e. compressed and purified air) to which the auxiliary refrigeration from the auxiliary refrigeration circuit 60 is provided.
• the second tie-in point 120 is within the booster air compression circuit 30 and is configured to divert a fraction of the further compressed third portion of the compressed and purified stream as compressed stream s 62A, 62B to the auxiliary refrigeration circuit 60.
• This second tie in point 1 10 provides a working fluid (i.e. boosted compressed air) that is to be expanded to provide a portion of the auxiliary refrigeration from the auxiliary refrigeration circuit 60.
• the third tie-in point 130 is located within the distillation column system 50 and is configured to return the cooled carrier fluid 69 (i.e. compressed and purified air) as well as the warmed working fluid 66 (i.e. fully warmed, expanded working fluid) to the higher pressure column 54.
• the fourth tie-in point 140 is located within the first refrigeration circuit 20 and is configured to divert a portion 28 of the first refrigeration stream 22 to the auxiliary refrigeration circuit 60 where it provides further cooling or refrigeration to the carrier stream 19 via indirect heat exchange in the auxiliary heat exchanger 65.
• a fifth tie in point 150 is also required in the embodiment shown in Fig. 2.
• This fifth tie-in point 150 is also located within the first refrigeration circuit 20 and configured to return a portion of the partially warmed, expanded working fluid 27 back to the first refrigeration circuit 20 upstream of the first turbo-expander 26.
• the supplemental or auxiliary refrigeration system is configured and constructed as a portable, skid-mounted refrigeration system that can be easily added to the cryogenic air separation plant/unit after initial plant construction in a manner that minimizes cold-box entry.
• the preferred skid-mounted supplemental or auxiliary refrigeration system would include: (i) one or more auxiliary compressors 63; (ii) the warm second turbo-expander 64; (iii) the auxiliary heat exchanger 65; (iv) associated piping to facilitate the above-identified four or five tie-in points; and (v) one or more control valves 67A, 67B, 67C, and 67D configured to control the air stream flows to the one or more auxiliary compressors 63, second turbo-expander 64, and auxiliary heat exchanger 65 as described above with reference to Figs.
• some of the flow control valves 67A, 67B, 67C, and 67D configured to control the air stream flows to the one or more auxiliary compressors 63, second turbo-expander 64, and auxiliary heat exchanger 65 may be configured as part of the cryogenic air separation plant and where the skid-mounted supplemental or auxiliary refrigeration system is tied-in downstream of such control valves.
• the presently disclosed system can easily switch between a high gaseous product cycle - when the flow control valves are closed and a high liquid make cycle where the flow control valves are operated to produce an increased amount of refrigeration and associated liquid product make.
• An advantage of the present system and method for providing auxiliary refrigeration to a cryogenic air separation plant is the ability to increase the amount of refrigeration and associated liquid product make in a cost-effective manner.
• the amount of refrigeration produced and amount of liquid make is adjusted by varying the warm turbine inlet pressure and flow in the supplemental or auxiliary refrigeration circuit. Adjustments to the warm turbine inlet pressure and flow are effected by selectively opening and/or closing the one or more flow control valves 67 A, 67B, 67C, and 67D.
• the discharge flow from the warm second turbo-expander is passed through the auxiliary heat exchanger and then directed to the higher pressure column along with the main air (i.e. cooled second portion of the of the compressed and purified feed air stream) and the fourth portion of the of the compressed and purified feed air stream exiting the auxiliary heat exchanger.
• An additional advantage presented by the present system and method is that by diverting a portion of the first refrigeration stream from the primary refrigeration circuit to the auxiliary refrigeration circuit and thus bypassing the lower pressure column separation, the gaseous oxygen product produced by the distillation column system is reduced but the argon recovery within the distillation column system can be maintained or possibly enhanced.
• diverting a portion of the first refrigeration stream to the auxiliary refrigeration circuit is preferably controlled to balance the temperatures in auxiliary heat exchanger and preserve recovery in the auxiliary booster-turbine arrangement.
• the flow and pressure ratio within the primary refrigeration circuit is maximized.
• the upper column turbine arrangement is used more as a heat pump to improve liquid making capability of the cryogenic air separation plant.

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• 2016
  • 2016-01-22 US US15/004,210 patent/US20170211881A1/en not_active Abandoned
  • 2016-08-26 WO PCT/US2016/048884 patent/WO2017127136A1/en active Application Filing
  • 2016-08-26 EP EP16759960.4A patent/EP3405726B1/de active Active
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