CN104685310A - Air separation method and apparatus - Google Patents

Air separation method and apparatus Download PDF

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Publication number
CN104685310A
CN104685310A CN201280049443.9A CN201280049443A CN104685310A CN 104685310 A CN104685310 A CN 104685310A CN 201280049443 A CN201280049443 A CN 201280049443A CN 104685310 A CN104685310 A CN 104685310A
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CN
China
Prior art keywords
stream
air
pressure column
liquid
oxygen
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CN201280049443.9A
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Chinese (zh)
Inventor
H.E.霍华德
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Praxair Technology Inc
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Praxair Technology Inc
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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
    • F25J3/04078—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
    • F25J3/0423—Subcooling of liquid process streams
    • 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
    • F25J3/04406—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

Abstract

A cryogenic air separation method and apparatus in which a lower pressure distillation column is configured to receive, at successively higher locations of the lower pressure column and at successively lower temperatures, crude oxygen derived from a crude liquid oxygen stream discharged from a higher pressure column, an intermediate reflux stream and a nitrogen-rich reflux stream. All of the streams are subcooled and depressurized. The subcooling is conducted such that the intermediate reflux stream and the nitrogen-rich liquid stream cocurrently, indirectly exchange heat to a nitrogen-rich vapor stream withdrawn from the lower pressure column and the intermediate reflux stream is subcooled to a temperature between the temperatures over which the nitrogen-rich liquid stream is subcooled. Additionally, the crude liquid oxygen stream and the intermediate reflux stream can, cocurrently, indirectly exchange heat to a pressurized liquid stream used in forming an oxygen product and the nitrogen-rich vapor stream.

Description

Air separating method and equipment
Technical field
The present invention relates to a kind of method and apparatus for separating of air, to compress wherein and the air purified is separated within destilling tower unit, in destilling tower unit, cold decompression is crossed in thick liquid oxygen tower bottom product (bottom), intermediate reflux (it can be liquia air) and the backflow of rich nitrogen, and is introduced in lower pressure column at temperature lower continuously in position higher continuously.More specifically, the present invention relates to a kind of method and apparatus, the excessively cold of intermediate reflux is wherein enhanced, to improve the production of oxygen product and/or argon product.
Background technology
Air is by equipping in (plant) distillation carried out in air separation to be separated into its component portion.This type of equipment adopts main air compressor to carry out compressed air, adopt preliminary clearning (prepurification) unit to come to remove higher pollutant (such as carbon dioxide, steam and hydrocarbon etc.) from air, and adopt main heat exchanger by compressing of producing and the Air flow purified to the cryogenic temperature being suitable for it and carrying out distilling in destilling tower unit.Destilling tower unit adopts higher pressure column, lower pressure column and adopts argon column alternatively when argon is expected product.When this type of equipment is located in ambient (enclave), the parts of air separation equipment can share.Such as, main air compressor and clean unit can be used to as two or more destilling tower cell compression air.
The air compressed is introduced in higher pressure column and rectifying becomes thick liquid oxygen tower bottom product (being also known as still liquid (kettle liquid)) and nitrogen rich vapor overhead product (overhead).The stream of thick liquid oxygen is introduced in lower pressure column, for refining further within lower pressure column, to produce oxygen enriched liquid tower bottom product and the nitrogen rich vapor overhead product of this lower pressure column.Lower pressure column is run at low pressures, to enable the nitrogen rich vapor overhead product of oxygen enriched liquid condensation higher pressure column at least partially, for two towers that reflux object and for producing nitrogen product from condensate.Therefore, higher pressure column and lower pressure column are operably associated each other with heat transfer relation.From the oxygen enriched liquid of destilling tower unit, the returning stream and can be introduced in main heat exchanger, to help cooling-air of nitrogen rich vapor.This type of returns stream and heats within main heat exchanger, and is retrieved as oxygen product and nitrogen product.
When argon is expected product, argon column can be connected in lower pressure column, the steam stream containing argon and oxygen removed from lower pressure column with rectifying.In addition, when under high pressure (being supercritical pressure potentially) desirably oxygen and/or nitrogen product time, heat exchanger can be pumped in lower pressure column and heat in a heat exchanger subsequently as the stream of the oxygen enriched liquid of tower bottom product generation and/or as the stream of the nitrogen-rich liquid of condensate generation, to produce HCS or supercritical fluid.Typically, by after being compressed in main air compressor by air, further compressed-air actuated part in booster compressor, provides the heat exchange duty (duty) for this type of object.The charge air flow of gained is liquefied, and liquid air stream can be introduced into higher pressure column or lower pressure column or introduce in these two towers.In this regard, typically, liquia air is introduced in lower pressure column as intermediate liquid backflow stream (reflux stream) containing aerobic and nitrogen, and this type of flows through with the nitrogen enriched vapor stream indirect heat exchange obtained from the top of lower pressure column with excessively cold together with thick liquid oxygen tower bottom product at the nitrogen rich vapor of the condensation used in lower pressure column that refluxes.All these streams will enable these streams be introduced into pressure in lower pressure column being decompressed to by expansion valve after cold.Decompression also makes stream cool further.The cooling of stream can be vital for thick liquid oxygen stream, and for this type of tower of backflow and the object obtaining argon product, thick liquid oxygen stream must lower the temperature the condensation to the rich argon steam produced in argon column is carried out.
Usually, argon recovery and oxygen reclaim and can be limited by the factor of any amount.Such as, argon reclaims the total amount restriction that can be subject to being applied by the bottom of lower pressure column by the mode of the nitrogen condensation of the nitrogen rich vapor from higher pressure column the steam stream of (impart).Alternatively, the top section of lower pressure column can have backflow not enough for the liquid vapors ratio (liquid to vapor ratio) maintained to fully catch needed for most of argon/oxygen for reclaiming.Latter one of what the present invention paid close attention to is problems.When pressurized product is produced by pumping, argon reclaims also impaired, is the remarkable minimizing of the high-quality reflux fluid (reflux flow) owing to can be used for upper column greatly.Usually, for the object of liquid oxygen pumping, percent 30 of air can be liquefied to more than percent 35.Directly available upper column backflow also will be made to reduce from the process of ice chest extraction major part pressurization nitrogen.Production along with the liquefied air of liquid pumping circulation (or have high liquid make (high liquid make)) typically divides between elevated pressures nitrogen rectifying section and lower pressure nitrogen rectifying section.Liquia air is only partly excessively cold within main heat exchanger before flash distillation (flash) enters in Tower System.Argon is caused to reclaim upper measurable decline by the flash gas produced the liquia air throttling entered in upper pressure tower/low pressure tower.
[0006] in order to make the production of liquid oxygen and/or Liquid Argon maximize, upper zone liquid backflow as much as possible being caused lower pressure column is necessary.This type of liquid backflow be introduced in lower pressure column in downward direction on drive oxygen and argon, to improve recovery.Therefore, liquia air, thick liquid oxygen and the backflow of rich nitrogen to be generally inflated and whole excessively cold before introducing in lower pressure column, to prevent from forming steam at the decompression of this type of stream.In addition, it is also known that refluxed thick liquid oxygen, liquia air and rich nitrogen is chilled to temperature lower continuously, to optimize the amount of the liquid backflow of the upper zone being applied to lower pressure column, and therefore improves oxygen further and to reclaim and/or argon reclaims.
As this type of excessively cold example of having discussed above can at US 5,878, find in 597.In this patent, the oxygen-rich stream that the oxygen enriched liquid produced from the tower bottom product as lower pressure column obtains is pumped and heats, to produce pressurized oxygen product.What entered by compression further in booster compressor is compressed and a part for the air purified, provides the heat exchange duty for this type of heating.Heat exchange result in the liquefaction of the air be further compressed and the production of liquid air stream.Liquid air stream is introduced in higher pressure column as intermediate reflux stream after expanding in expansion valve.This type of stream is called as " intermediate reflux stream ", because it is introduced in the centre position of lower pressure column between the position that rich nitrogen backflow and thick oxygen are introduced into.By it is noted that vicinity likely by being introduced at the liquia air place of being introduced into or liquia air removes this type of stream from dropping liq and forms this type of intermediate reflux within higher pressure column.In any case intermediate reflux stream containing aerobic and nitrogen, and will will have the nitrogen cut (fraction) larger than the nitrogen component of thick liquid oxygen.In this patent, intermediate reflux stream is excessively cold within sub-cooling unit before being introduced into the centre position of lower pressure column.Sub-cooling unit was also used for the cold thick liquid oxygen stream be made up of the thick liquid oxygen of producing in higher pressure column and the backflow stream be made up of the nitrogen rich vapor of the condensation of producing in higher pressure column.Sub-cooling unit is designed so that the backflow stream that thick liquid oxygen stream, intermediate reflux and the nitrogen rich vapor by condensation form is chilled to temperature lower continuously excessively, as mentioned above.But this type of is excessively cold strides across temperature range lower continuously and occurs, and does not have overlap between these scopes.Due to this type of heat exchange, intermediate reflux stream will cause being formed the temperature of significant flash gas/steam by having when being introduced into lower pressure column.This will affect argon negatively and reclaim and oxygen recovery.In addition, heat exchange itself by for poor efficiency because cooling unit will have the high temperature difference added between hot-fluid and cool stream.In this patent, cold hot-fluid is added or multiple hot-fluid that adds is the useless nitrogen stream that the nitrogen product stream that obtains from the top of lower pressure column and the position under the top of this lower pressure column remove from lower pressure column for carrying out heat exchange duty.
As discussed, the invention provides a kind of method and apparatus for separating of air, wherein, by more effectively transmitting heat adding between hot-fluid and cool stream crossing between cold period, the intermediate reflux stream being delivered to lower pressure column compared with prior art by more optimally excessively cold.In other words, heating curves and cooling curve closer to together with, cause intermediate reflux stream to be crossed and be chilled to the temperature lower than temperature possible in prior art.The flash vapors when being introduced in lower pressure column will be made according to of the present invention the temperature formed in intermediate reflux stream to be reduced the optimised cold of intermediate reflux stream, and therefore improve oxygen recovery and/or argon recovery.
Summary of the invention
On the one hand, the invention provides a kind of air separating method, wherein air is separated in cryogenic rectification process, at least to produce oxygen product stream.When in this article and when using in the claims, term " cryogenic rectification process " refers to following any process, to compress wherein and the air purified is cooled to temperature near its dew point or its dew point, and be introduced into subsequently in air gas separation unit, described air gas separation unit comprises higher pressure column and lower pressure column, described higher pressure column and lower pressure column operably associated with each other with heat transfer relation, airdistillation to be become oxygen product and rich nitrogen product, and also possibly, argon product.
Cryogenic rectification process of the present invention uses destilling tower unit, the lower pressure column that this destilling tower unit has higher pressure column and operably associates with this higher pressure column with heat transfer relation.The place of higher position continuously that lower pressure column is formed at lower pressure column receives thick oxygen, intermediate reflux stream and the rich nitrogen backflow that formed by the thick liquid oxygen stream of discharging from higher pressure column at least partially.
Cryogenic rectification process comprises the decompression at least partially making thick liquid oxygen stream, intermediate reflux stream and rich nitrogen backflow stream, and makes thick liquid oxygen stream, intermediate reflux stream and rich nitrogen backflow stream carry out to be chilled to temperature lower continuously by carrying out indirect heat exchange with at least nitrogen enriched vapor stream obtained from lower pressure column before depressurizing.In this regard, nitrogen enriched vapor stream employs for " at least ", because can be the nitrogen enriched vapor stream obtained from the top of lower pressure column, the impure nitrogen enriched vapor stream (being also known as useless nitrogen stream in the art) obtained under the top of lower pressure column or these two kinds streams.Intermediate reflux stream and nitrogen-rich liquid stream within the temperature range of overlap and stream (cocurrently), indirectly with at least nitrogen enriched vapor stream exchanged heat, intermediate reflux stream is crossed and is chilled to nitrogen-rich liquid stream by the temperature crossed between the temperature range of cold experience.When in this article with in claims use time, term " and stream " represent related streams indirectly simultaneously exchanged heat at least nitrogen enriched vapor stream, and further in the same direction under the background (context) of heat exchange flow.
And flow heat exchange as a result, within the heat exchanger crossing cold object for this by the heating curves of the fluid of heating and cooling and cooling curve by than the closer coincidence in prior-art devices.As a result, intermediate reflux stream is as cold as crossing than larger degree of the prior art.As described above, thick liquid oxygen stream, intermediate reflux stream and nitrogen-rich liquid stream all originate under the pressure higher than the pressure of lower pressure column, and therefore they must be decompressed to the pressure being suitable for being introduced in lower pressure column.The decompression of all these streams also reduces their temperature, and this is necessary when thick liquid oxygen stream, refluxes to enable this type of stream condensation argon column.But as is known in the art and as discussed above, this type of decompression also causes considerable vapor fraction to be formed in each stream.Backflow stream containing aerobic and nitrogen is crossed larger and is chilled to the temperature lower than temperature possible in prior art and result in occurred more liquid distillate significantly in this type of backflow stream, to order about oxygen and argon declines in tower, their recovery is brought up on the air separating method of prior art.In this regard, preferably, thick liquid oxygen stream is crossed is as cold as another temperature, and another temperature described is equal to or higher than the temperature of the nitrogen-rich liquid stream before the mistake of nitrogen-rich liquid stream is cold, and the backflow stream that another temperature described is positioned at containing oxygen and nitrogen is crossed within the temperature range of cold experience.Thick liquid oxygen stream preferably from another temperature by excessively cold, described another temperature is higher than the temperature of the intermediate reflux stream before the mistake of intermediate reflux stream is cold.This made the difference between cold period between heating curves and cooling curve reduce further, is crossed the degree be as cold as increase further to make intermediate reflux stream.
In a particular embodiment of the present invention, air is separated by cryogenic rectification process, to produce at least oxygen product stream, and oxygen product is flowed through to heat to the liquid stream of having pressurizeed to be formed.In this type of embodiment, be only required of thick liquid oxygen stream or thick liquid oxygen stream and intermediate reflux stream and flow ground, indirectly exchanged heat to the liquid stream of having pressurizeed and at least nitrogen enriched vapor stream.The increase of the liquid stream of having pressurizeed provides is crossing some the heat trnasfer loads be chilled to less in thick liquid oxygen stream, this is crossing allowing the larger task of heat trnasfer load by least nitrogen enriched vapor stream supply in cold intermediate reflux stream, and allows this type of stream to be crossed thus to be chilled to than degree larger in prior art.
Destilling tower unit also can be provided with argon column.In such cases, crude argon steam stream obtains and rectifying argon column from lower pressure column, to produce rich argon vapor overhead product and to contain oxygen column bottom product.By being introduced in lower pressure column containing oxygen stream of forming containing oxygen column bottom product.Thick liquid oxygen stream at least partially crossed cold after be inflated and carry out indirect heat exchange with the rich argon steam stream be made up of rich argon vapor overhead product, thus make partly gasifying at least partially and making rich argon steam condensation of thick liquid oxygen stream, to form the liquid and gas at least partially of rich argon liquid stream and thick liquid oxygen stream.A part for rich argon liquid stream is discharged as argon product stream, and another part of rich argon liquid stream is introduced in argon column as argon column backflow stream.The liquid phase stream be made up of thick liquid oxygen and vapor phase stream are introduced in lower pressure column, and are formed and be introduced into thick oxygen in lower pressure column at least partially.
Air can be compressed and purify to be formed and be compressed and the air stream purified, and this compressed and a part for the air stream purified by cooling with nitrogen enriched vapor stream indirect heat exchange, and to be after this introduced in higher pressure column.By compress further compress and the another part of the air stream purified with formed boost pressure compress and the air stream purified, pumping oxygen enriched liquid stream at least partially with form the liquid stream of having pressurizeed and by with boost pressure compress and the air stream indirect heat exchange purified heats this liquid stream of having pressurizeed at least partially, form oxygen product stream.This produces oxygen product from the liquid stream of having pressurizeed, and compressing and the generation liquid air stream at least partially of the air stream purified from boost pressure.Intermediate reflux stream forming at least partially by liquid air stream.In an embodiment of the present invention, wherein thick liquid oxygen stream or thick liquid oxygen stream and intermediate reflux stream can and flow ground, indirectly exchanged heat to the liquid stream of having pressurizeed and at least nitrogen enriched vapor stream, the liquid stream of having pressurizeed and oxygen product stream can be formed in the mode directly set forth above.
In any embodiment of the invention, boost pressure compress and the Part I of the air stream purified can be completely cooled and form liquid air stream.Boost pressure compress and the Part II of the air stream purified is already partially cooled and is introduced in turbo-expander (turboexpander), to form exhaust stream.Exhaust stream is introduced in higher pressure column and lower pressure column, refrigeration to be exerted in cryogenic rectification process.
On the other hand, the invention provides a kind of air separation equipment.This air separation equipment comprise air separation equipment, this air separation equipment construction for be separated air by cryogenic rectification, at least to produce oxygen product stream.When in this article and when using in claim, term " air separation equipment " refers to the equipment with main heat exchanger, with will compress and the Air flow purified to the temperature being suitable for its rectifying within the air gas separation unit with destilling tower unit, this destilling tower unit comprises higher pressure column and lower pressure column, higher pressure column operably associates with heat transfer relation with lower pressure column, airdistillation to be become oxygen cut and rich nitrogen cut, and this destilling tower unit also comprises argon column possibly, so that air is distilled into Argon fraction further.
According to the present invention, air separation equipment has destilling tower unit, and this destilling tower unit comprises higher pressure column and the lower pressure column operably associated with this higher pressure column with heat transfer relation.The place of higher position continuously that lower pressure column is formed at lower pressure column receives thick oxygen, intermediate reflux stream and the rich nitrogen backflow stream that formed by the thick liquid stream of discharging from higher pressure column at least partially.What also comprise is one group of expansion valve and mistake cool-heat-exchanger.When in this article with claims in use time, term " cross cool-heat-exchanger " refers to any heat exchanger crossing cold object for this type of, and can be independent unit, or to be incorporated in main heat exchanger and to form the part of main heat exchanger thus.
Expansion valve is made the decompression at least partially of thick liquid oxygen stream, intermediate reflux stream and rich nitrogen backflow stream by locating.Cross cool-heat-exchanger be positioned in the upstream of expansion valve and be connected to lower pressure column, to receive at least nitrogen enriched vapor stream from lower pressure column.Cross cool-heat-exchanger to be constructed, thick liquid oxygen stream, intermediate reflux stream and nitrogen-rich liquid are flowed through carry out indirect heat exchange with at least nitrogen enriched vapor stream to be as cold as temperature lower continuously.Intermediate reflux stream and nitrogen-rich liquid stream also flow ground, indirectly exchanged heat at least nitrogen enriched vapor stream, and intermediate reflux stream is crossed and is chilled to nitrogen-rich liquid stream by the temperature between the temperature of cold experience excessively.Preferably, cross cool-heat-exchanger and also can be constructed, thick liquid oxygen stream is crossed and is as cold as another temperature, another temperature be equal to or greater than nitrogen-rich liquid flow through cold before the temperature of nitrogen-rich liquid stream, and be positioned at intermediate reflux stream and crossed the temperature range of cold experience.More preferably, cross cool-heat-exchanger and be also constructed, make thick liquid oxygen stream from another temperature by excessively cold, the temperature of the intermediate reflux stream before another temperature is cold higher than the mistake of intermediate reflux stream.
In another specific embodiment of the present invention, air separation equipment is constructed, to be separated air by cryogenic rectification, to produce at least oxygen product stream from the liquid stream of having pressurizeed.In this type of embodiment, cross cool-heat-exchanger and can be constructed such that under minimum level, thick liquid oxygen stream or thick liquid oxygen stream and intermediate reflux stream also flow ground, indirectly exchanged heat to the liquid stream of having pressurizeed and at least nitrogen enriched vapor stream.
Destilling tower unit also can be provided with argon column.Argon column is connected in lower pressure column, and crude argon steam stream is obtained and rectifying argon column from lower pressure column, to produce rich argon vapor overhead product and to contain oxygen column bottom product, and by being introduced in lower pressure column containing oxygen stream of forming containing oxygen column bottom product.Additionally provide argon condenser, and an expansion valve in one group of expansion valve is positioned between sub-cooling unit and argon condenser, make thick liquid oxygen stream at least partially by cross cold after expansion.Argon condenser to be connected on argon column and to be connected on expansion valve, and be constructed so that thick liquid oxygen stream at least partially by cross cold and expand after by carrying out indirect heat exchange with the rich argon steam stream be made up of rich argon vapor overhead product, make partly gasifying at least partially and making rich argon steam condensation of thick liquid oxygen stream thus, to form the liquid and gas at least partially of rich argon liquid stream and thick liquid oxygen stream.A part for rich argon liquid stream is discharged from argon condenser to form argon product stream, and another part of rich argon liquid stream is introduced into argon column from argon condenser as argon column backflow.Argon condenser is connected in lower pressure column, and the liquid phase stream that is made up of liquid and gas and gas phase stream are introduced in lower pressure column respectively, is introduced into thick oxygen in lower pressure column at least partially to be formed.
This air separation equipment can be provided with: main heat exchanger; Main air compressor, its compressed air; Clean unit, it is connected in main air compressor, to purify air after air is by compression, and is formed thus and has compressed and the air stream purified.Booster compressor is connected on clean unit, is further compressed and the air stream purified to be formed.Main heat exchanger is connected between clean unit and higher pressure column, and be constructed to compress and a part for the air stream purified by carrying out indirect heat exchange to cool with nitrogen enriched vapor stream, and to be introduced in higher pressure column.Pump is connected on destilling tower unit, the liquid stream of having pressurizeed is formed at least partially with pumping oxygen enriched liquid stream, and main heat exchanger is connected on booster compressor, and be constructed by with boost pressure compress and the air stream purified carries out indirect heat exchange, heat the liquid stream of having pressurizeed at least partially, thus from boost pressure compress and the air stream purified produce liquid air stream at least partially.Main heat exchanger becomes to flow with lower pressure column and is communicated with, and another expansion valve in expansion valve group is positioned between sub-cooling unit and lower pressure column, make liquid air stream at least partially cross excessivelys cold in cool-heat-exchanger, expand and introduce in lower pressure column, and the intermediate liquid backflow formed thus containing aerobic and nitrogen is flowed.Cross cool-heat-exchanger can be connected between lower pressure column and main heat exchanger, and be constructed so that partly to heat oxygen enriched liquid stream by carrying out indirect heat exchange with thick liquid oxygen stream between the mistake cold period of thick liquid oxygen stream.In embodiment discussed above, wherein cross cool-heat-exchanger to be constructed to make thick liquid oxygen stream or thick liquid oxygen stream and intermediate reflux stream and flow ground, indirectly exchanged heat to the liquid stream of having pressurizeed, and at least nitrogen enriched vapor stream, the liquid stream of pressurizeing and oxygen product stream can be formed in the mode set forth above.
Air separation equipment can have turbo-expander, this turbo-expander is connected in lower pressure column and higher pressure column, in one that makes the exhaust stream produced by turbo-expander be introduced in lower pressure column and higher pressure column, refrigeration is exerted in air separation equipment.Main heat exchanger is constructed to make compressing of boost pressure and the Part I of the air stream purified is completely cooled and forms liquid air stream, and boost pressure compress and the Part II of the air stream purified is already partially cooled and discharges from main heat exchanger.Turbo-expander is connected on main heat exchanger, make boost pressure compress and the Part II of the air stream purified expands to produce exhaust stream in turbo-expander.
Accompanying drawing explanation
Although this description ending claims clearly indicate the theme of the present invention that applicant thinks, it is believed that by reference to the accompanying drawings time will understand the present invention better, wherein:
Fig. 1 is the schematic diagram for implementing the air separation equipment according to method of the present invention; And
Fig. 2 represents along the figure crossing the example of the temperature of the length of cool-heat-exchanger of the present invention.
Detailed description of the invention
With reference to Fig. 1, illustrate air separation equipment 1, this air separation equipment 1 is designed to carry out cryogenic rectification process, to produce the oxygen product and argon product that have pressurizeed.But, the present invention is not limited thereto kind equipment, and there is the more generally application of this kind equipment any being used for producing oxygen product, with or without argon product for design.
More specifically, in air separation equipment 1, conveying air stream 10 is compressed by main air compressor 12, and purifies in clean unit 14 subsequently.Main air compressor 12 can be multi-grade machines, and with intercooler between these level and aftercoolers, with the heat by removing compression from final level.Although not shown, independent aftercooler directly can be arranged on the downstream of compressor 12.Prepurification unit 14 as known to those skilled in the art can comprise the bed of absorbent (such as, aluminium oxide or molecular sieve type absorbent) to absorb the higher impurity contained in air, and therefore carries air stream 10.Such as, as everyone knows, this type of higher impurity will comprise steam and carbon dioxide, and steam and carbon dioxide will freeze and gather under the low rectification temperature planning (contemplate) by air separation equipment 1.In addition, hydrocarbon also can be absorbed, and it can assemble within oxygen enriched liquid, and presents security risk thus.
Gained compress and the air stream 16 purified is divided into first subsequently attachedly to have compressed and the air stream 18 purified and second has attachedly compressed and the air stream 20 purified.First attachedly to have compressed and the air stream 18 purified is cooled to close to saturated in main heat exchanger 22.Although will it is noted that main heat exchanger 22 is illustrated as individual unit, as skilled generals will, for cooling-air and for carry out other heat exchange operation really cutting mechanism can be different from illustrated mechanism.Typically, the mechanism utilized can be made up of two or more heat exchangers be connected in parallel, and further, each in this type of heat exchanger can be divided into multiple section at its hot junction (warm end) and cold junction place.In addition, heat exchanger can to connect design (banked design) Further Division, the heat exchange duty that wherein needs at elevated pressures (such as supercharging compress and between the air stream 53 purified and the Part I 104 at least partially of liquid stream 108 pressurizeed, two streams all will be discussed) implement in one or more hp heat exchanger.Other heat exchange duty of carrying out at low pressures is implemented in lower pressure heat exchanger, such as, attachedly to have compressed and between the air stream 18 purified and nitrogen enriched vapor stream 94, this also will discuss first.This type of heat exchangers all can be plate-fin design, and in conjunction with the constructed of aluminium of brazing.The heat exchanger of spiral winding is possible alternative for elevated pressures heat exchanger.
The compressing of gained, to purify and the stream 24 cooled is introduced into subsequently and has in the destilling tower unit 26 of higher pressure column 28 and lower pressure column 30 and argon column 32.Specifically, compress, to have purified and the stream 24 cooled is introduced in higher pressure column 28, run under the pressure of higher pressure column 28 between about 5 to about 6 bar (absolute pressure), and be therefore noted as " higher ", reason is that higher pressure column 28 is run under the pressure higher than the pressure of lower pressure column 30, lower pressure column 30 is noted as " lower ", and reason is that lower pressure column 30 is run under the pressure lower than the pressure of higher pressure column 28.Higher pressure column 28 is provided with the quality usually marked by reference number 34 and 36 and transmits contact element (mass transfer contact element), and quality is transmitted contact element and contacted with the liquid phase of decline for making the liquid phase of rising of mixture (air) to be separated.Along with gas phase rises in tower, it becomes more is rich in nitrogen, and to produce nitrogen rich vapor overhead product 76 and thick liquid oxygen tower bottom product 50 (being also known as still liquid), they will further refining in lower pressure column 30.Mass transfer elements can be made up of the combination of structured packing, tower tray (tray), random packing or this class component.Lower pressure column 30 is provided with this type of mass transfer elements usually marked by reference number 38,40,42,44 and 46, and argon column 32 is also provided with the mass transfer elements usually marked by reference number 48.
Second attachedly to have compressed and the air stream 20 purified compresses further in booster compressor 52, to produce compressing and the air stream 53 purified of the boost pressure be introduced in main heat exchanger 22.Boost pressure compress and the air stream 53 purified be configured to enter whole air of air separation equipment 1 about percent 30 to about percent 40 between.Boost pressure compress and the Part I 54 of the air stream 53 purified is removed from main heat exchanger 22 after its part is crossed, and expand in expansion turbine 56, to produce refrigeration by producing exhaust stream 58 under the pressure between about 1.1 to about 1.5 bar (absolute pressure), exhaust stream 58 is imported in lower pressure column 30.Typically, boost pressure compress and the Part I 54 of the air stream 53 purified forms compressing of boost pressure and between about percent 10 of the air stream 53 purified to about percent 20.It is to be noted that the shaft work expanded can be applied to the compression of expansion flow, or for compressing the object of another process streams or generation electric power.As known in the art, in order to such as compensate warm end losses in heat exchanger, enter the heat leak in equipment and produce the object of liquid, refrigeration must be exerted in air separation equipment.In this area, also other means known produce this type of refrigeration, such as, introduce in higher pressure column by gas turbine exhaust, the nitrogen of nitrogen-enriched stream expands (nitrogen-enriched stream taken out from lower pressure column after its part is heated) and other expansion cycles as known in the art.Likely freeze comparably from external source and apply, can be so when air separation equipment ambient.Boost pressure compress and the Part II of the air stream 53 purified or remainder cool in main heat exchanger 22 time form liquid air stream 60, liquid air stream 60 has at about 98K to the temperature in the scope between about 103K.By it is noted that boost pressure compress and the Part I 54 of the air stream 53 purified by intergrade place from booster compressor 52 remove stream and compress this stream further to produce subsequently.Second boost pressure compress and the air stream 53 purified can be introduced into subsequently in main heat exchanger 22 and fully to cross over main heat exchanger 22.
Part I 62 and Part II 64 is divided into after liquid air stream 60.Alternatively, the air stream liquefied partly reduces pressure by close phase (dense phase) decompressor (Liquid turbine) or expansion valve.The Part I 62 of liquid air stream 60 carries out valve expansion by expansion valve 66 and is introduced in higher pressure column 28, and Part II 64 forms intermediate reflux stream, its cross cross in cool-heat-exchanger 70 cold after pass through to expand through expansion valve 65, and to be introduced in lower pressure column 30.Will it is noted that other means can be used for forming intermediate reflux stream.Such as, intermediate reflux stream is formed by the following step: valve expands, and liquid air stream 60 is introduced in higher pressure column 28, and forms intermediate reflux stream in the position that liquid air stream 60 is introduced into by the dropping liq removed from higher pressure column 28 subsequently.In such cases, intermediate reflux stream is by component close for the component of the liquid air stream 60 had and enter.In addition, intermediate reflux stream can be formed by the dropping liq obtained in the higher position of higher pressure column 28.But in all cases, intermediate reflux stream will have the nitrogen cut higher than the nitrogen cut of thick liquid oxygen tower bottom product 50.
The thick liquid oxygen stream 68 be made up of the thick liquid oxygen tower bottom product 50 produced in higher pressure column 28 is excessively cold in mistake cool-heat-exchanger 70, and with the further refining of mode hereinafter also will discussed in lower pressure column 30.As being widely known by the people in this area, other means can be used, such as, enter crossing cold function i ntegration in a part for main heat exchanger 22.By it is noted that when utilizing independent sub-cooling unit, the physical location of heat exchanger can be necessary to need liquor pump, returns upper column to promote thick liquid oxygen.The refining of thick liquid oxygen creates the oxygen enriched liquid tower bottom product 72 of lower pressure column 30, partly evaporate in the condenser reboiler 74 of oxygen enriched liquid tower bottom product 72 in the bottom of lower pressure column 30, prevent nitrogen rich vapor overhead stream 76 condensation making to take out from higher pressure column 28.The nitrogen-rich liquid stream 78 of gained is divided into the first rich nitrogen backflow stream 80 and the second rich nitrogen backflow stream 82, first rich nitrogen backflow stream 80 and the second rich nitrogen backflow stream 82 and serves as backflow to higher pressure column 28 and lower pressure column 30 respectively.Second rich nitrogen backflow stream is formed by the following step: introduced in higher pressure column 28 by all nitrogen-rich liquid stream 78, and obtain impure nitrogen liquid stream from the lower position of higher pressure column 28 subsequently.
Second rich nitrogen backflow stream 82, crossing in cool-heat-exchanger 70 excessively cold, and to be expanded by expansion valve 86 valve at least in part as backflow stream 84, and is introduced in lower pressure column 30 as backflow.Liquid nitrogen product stream 87 obtains after can expanding in valve 88 alternatively.There is provided nitrogen enriched vapor stream 94 to crossing cold heat exchange duty, nitrogen enriched vapor stream 94 is made up of the overhead product from lower pressure column 30.After nitrogen enriched vapor stream is partly heated in mistake cool-heat-exchanger 70, this nitrogen enriched vapor stream is fully heated and is retrieved as nitrogen product stream 96 in main heat exchanger 22.Useless nitrogen miscarriage is wherein raw and from the device that the lower position of lower pressure column 30 obtains, this type of stream also can participate in cold heat exchange duty.
As diagram, the oxygen enriched liquid stream 78 be made up of oxygen enriched liquid tower bottom product 72 whole or alternatively a part by pump 100 pumping, to produce the liquid stream 102 of having pressurizeed.The Part I 104 of the liquid stream 102 of having pressurizeed can in main heat exchanger 22 with first attached compressed air stream 18 indirect heat exchange and being heated, to produce the oxygen product stream 106 pressurizeed.Depend on the compression levels of the liquid stream 102 of having pressurizeed, the oxygen product stream 106 pressurizeed will will be maybe HCS for supercritical fluid.Alternatively, a part 108 for the liquid stream 102 of having pressurizeed can expand at expansion valve 110 internal valve and be retrieved as oxygen enriched liquid product stream 112.As known to those of skill in the art, additionally or its alternatively, another liquid stream being rich in component being rich in nitrogen can be used for forming the product pressurizeed.
Argon column 32 runs under the pressure similar with the pressure of lower pressure column 30, and typically, depends on desired argon refining amount, by the progression between employing 50 grades to 180 grades.Conveying stream 114 containing gaseous state argon and oxygen is at least removed from lower pressure column 30 close to the some place of maximum in argon concentration, and in argon column 32, is distillated into rich argon vapor overhead product and oxygen enriched liquid tower bottom product containing argon with the transported substance of oxygen.Rich argon steam stream 115 condensation in the argon condenser 116 with housing 117 and core 118 be made up of the overhead product produced in argon column 32, to produce rich argon liquid stream 120.A part 122 for rich argon liquid stream 120 is back to argon column 32 as backflow stream 122, and a part 124 expands at expansion valve 126 internal valve and is retrieved as argon product stream 128.Depend on the number of level, this type of rich argon product can process to remove oxygen and nitrogen in a manner known in the art further.Such as, additional level can be combined in independent tower, with further refining argon product stream 128.Alternatively, argon product stream 128 can by the further refining of deoxidation (deoxo) unit to remove oxygen, and by light-duty destilling tower (lights distillation column) further refining with except denitrification.
The oxygen enrichment of the gained of the argon column 32 and liquid bottoms product of poor argon can be retrieved as stream 130, be back to lower pressure column 30 as poor argon liquid stream 134 subsequently by pump 132 pumping.It should be pointed out that the object for controlling, a part for pump effluent can turn back to the storage tank (sump) of tower 32 alternatively.
As discussed previously, the thick liquid oxygen stream 68 be made up of the thick liquid oxygen tower bottom product 50 of higher pressure column 28 is excessively cold in mistake cool-heat-exchanger 70, and is divided into the first attached thick liquid oxygen stream 138 and the second attached thick liquid oxygen stream 140 subsequently.First attached thick liquid oxygen stream 138 valve in expansion valve 142 expands and is introduced into and contains in the housing 117 of core 118, with condensation rich argon steam stream 115.This makes the first attached thick liquid oxygen stream 138 partly gasify and produce liquid and gas.The liquid phase stream 146 of the gentle phase composition of liquid-like phase thus and vapor phase stream 148 are introduced in lower pressure column 30, for the further refining of thick liquid oxygen tower bottom product 50 respectively.In addition, the second attached thick liquid oxygen stream 140 valve in valve 150 expands and is introduced in lower pressure column 30 subsequently, for further refining.
Cold in order to optimally make the intermediate reflux to lower pressure column flow through, crossing cool-heat-exchanger 70 is designed to make the Part II 64 (serving as intermediate reflux stream) of thick liquid oxygen stream 68, liquid air stream 60 and the second rich nitrogen backflow stream 82 to be as cold as temperature lower continuously, i.e. " T2 ", " T4 " and " T5 " by all crossing respectively with nitrogen enriched vapor stream 94 indirect heat exchange.But, from above discussed wherein excessively cold be that continuous print prior art is different, cross cool-heat-exchanger 70 be designed to serve as the Part II 64 of the liquid air stream 60 of intermediate reflux stream and the second rich nitrogen backflow stream 82 and flow ground, indirectly with nitrogen enriched vapor stream 94 heat exchange, and the Part II 64 of liquid air stream 60 is crossed is as cold as temperature " T4 ", temperature " T4 " is crossed between cold experience temperature, namely between temperature " T3 " and " T5 " between the second rich nitrogen backflow stream 82.As mentioned above, such effect reduced being separated of heating curves in cool-heat-exchanger 70 and cooling curve, and allow the Part II 64 of liquid air stream 60 to be crossed thus and be chilled to the temperature lower than temperature possible in prior art, and in the Part II 64 of liquid air stream 60, form significant vapor fraction after preventing from expanding in expansion valve 65.
Preferably, as diagram, thick liquid oxygen stream 68 is crossed from temperature " T0 " and is as cold as temperature " T2 ".Temperature " T2 " be more than or equal to the second rich nitrogen backflow stream 82 cross cold before temperature, also i.e. temperature " T3 ".In addition, this temperature " T2 " is positioned at the Part II 64 of liquid air stream 60 by the temperature range of the cold experience of mistake, also namely between " T1 " and " T4 ".This allowed the heating curves in cool-heat-exchanger 70 and cooling curve to mate more closely further, result in the lower temperature of the intermediate reflux stream being delivered to lower pressure column 30.As diagram, although " T0 " is higher than temperature " T1 ", for this type of temperature, possible but more not preferred embodiment be that " T0 " is the temperature lower than " T1 ".
In addition, as diagram, alternatively, cross cool-heat-exchanger 70 can be designed so that the Part II 64 of thick liquid oxygen stream 68 and liquid air stream 60 and flow ground indirect exchange heat to oxygen enriched liquid stream 78 and nitrogen enriched vapor stream 94.In possibility embodiment of the present invention, cross cool-heat-exchanger 70 and can be designed so that only thick liquid oxygen stream 68 participates in this heat exchange.Typically, the base portion of lower pressure column 42 typically will be positioned in about 70 foot to 100 foot places higher than ground level, and sub-cooling unit is positioned on ground level.As a result, oxygen enriched liquid stream 78 will be heated effectively crossing in cool-heat-exchanger 70, and thus temperature will be reduced to this type of stream be further cooled required temperature in main heat exchanger 22.In this regard, likely form oxygen product stream 106, it is pressurizeed by head (head), and this head produces due to difference in height discussed above, and any oxygen enriched liquid stream 78 of non-pumping.Also by it is noted that following embodiment of the present invention is also possible, wherein only the Part II 64 of thick liquid oxygen stream 68 or thick liquid oxygen stream 68 and liquid air stream 60 between the two ground connection exchanged heat to oxygen enriched liquid stream 78 and nitrogen enriched vapor stream 94.In possibility embodiment of the present invention, wherein only thick liquid oxygen stream 68 participates in indirect heat exchange, and cold or this stream and liquid air stream 60 the excessively cold of Part II 64 of mistake of the second rich nitrogen backflow stream 82 can be as carrying out in order in the prior art.In the case, if a part for the cold demand of the mistake of nitrogen enriched vapor stream 94 will be provided by oxygen enriched liquid stream 78 and more thermic load can be used for other stream, then the Part II 64 of liquid air stream will be crossed and is as cold as the temperature lower than the temperature of prior art.
Cross aluminium matter, fin type heat exchanger that cool-heat-exchanger 70 can be brazing.For the detailed design of reaching this type of heat exchanger of heat trnasfer demand of the present invention will be conventional design to those of skill in the art.With reference to Fig. 2, illustrated the example that may run of cool-heat-exchanger 70, the air separation equipment of contact shown in Fig. 1 and when not heating oxygen enriched liquid stream 78.Fig. 2 showed the composite curve of temperature difference in cool-heat-exchanger 70, and this composite curve is relative to hot side temperature, and is the difference between heating curves and cooling curve.As known in the art, this type of curve negotiating is produced by the stream of multiple streams of heating and cooling and enthalpy weighted average.By checking, in this particular example, bot 502 includes, in mistake cool-heat-exchanger 70, there is multiple narrow point (pinch point).But with typically seen about 96K is relative in the prior art, " T4 " (i.e. intermediate reflux stream temperature when crossing cold) will be 87.15K.Process simulation shows, liquia air (or in other words, backflow stream containing aerobic and nitrogen after decompression in expansion valve 65) decompression make flash gas reduce more than 70%, oxygen reclaims and improves about 0.4% and argon reclaims and improves about 1.7%.
Although describe the present invention with reference to preferred embodiment, as those of skill in the art will expect, when not departing from the spirit and scope of the present invention set forth in claims, many changes, interpolation and omission can be made.

Claims (18)

1. an air separating method, it comprises:
Air is separated, to produce at least oxygen product stream by cryogenic rectification process;
Described cryogenic rectification process uses destilling tower unit, described destilling tower unit has higher pressure column and lower pressure column, described lower pressure column operably associates with described higher pressure column with heat transfer relation, and described lower pressure column is configured to receive at the continuous print higher position place of described lower pressure column thick oxygen, intermediate reflux stream and the rich nitrogen backflow stream that formed by the thick liquid oxygen stream of discharging from described higher pressure column at least partially;
Described cryogenic rectification process comprises, make described the decompression at least partially of described thick liquid oxygen stream, described intermediate reflux stream and described rich nitrogen backflow stream, and before depressurizing and by with at least nitrogen enriched vapor stream indirect heat exchange obtained from described lower pressure column, described thick liquid oxygen stream, described intermediate reflux stream and described rich nitrogen are flow through and are chilled to temperature lower continuously; And
Described intermediate reflux stream and described rich nitrogen flow and flow ground, indirectly exchanged heat to described at least nitrogen enriched vapor stream, described intermediate reflux stream is crossed and is chilled to described nitrogen-rich liquid stream by the temperature crossed between the temperature of cold experience.
2. an air separating method, it comprises:
Be separated air to produce at least oxygen product stream by cryogenic rectification process, and described oxygen product flowed through heat the liquid stream of having pressurizeed to be formed;
Described cryogenic rectification process uses destilling tower unit, described destilling tower unit has higher pressure column and lower pressure column, described lower pressure column operably associates with described higher pressure column with heat transfer relation, and is constructed to receive at the place of higher position continuously of described lower pressure column thick oxygen, intermediate reflux stream and the rich nitrogen backflow stream that formed by the thick liquid oxygen stream of discharging from described higher pressure column at least partially;
Described cryogenic rectification process comprises described the decompression at least partially making described thick liquid oxygen stream, described intermediate reflux stream and described rich nitrogen backflow stream, and before depressurizing and by with at least nitrogen enriched vapor stream indirect heat exchange obtained from described lower pressure column, described thick liquid oxygen stream, described intermediate reflux stream and described rich nitrogen are flow through and are chilled to temperature lower continuously; And
Make described thick liquid oxygen stream or described thick liquid oxygen stream and described intermediate reflux stream and flow ground, indirectly exchanged heat to described liquid stream of having pressurizeed and described at least described nitrogen enriched vapor stream.
3. method according to claim 1, wherein, described thick liquid oxygen stream is crossed is as cold as another temperature, another temperature described is equal to or greater than the temperature of the described rich nitrogen backflow before the described mistake of described rich nitrogen backflow stream is cold, and another temperature described is positioned at described intermediate reflux stream by within the temperature range of the cold experience of mistake.
4. method according to claim 3, wherein, makes described thick liquid oxygen stream excessively cold from another temperature, and described another temperature is than higher in the temperature making described intermediate reflux stream before the described mistake of described intermediate reflux is cold.
5. method according to claim 1 and 2, wherein:
Described destilling tower unit also has argon column;
Crude argon steam stream obtains and rectifying described argon column from described lower pressure column, to produce rich argon vapor overhead product and to contain oxygen column bottom product;
By by described containing oxygen column bottom product form contain oxygen stream introduce in described lower pressure column;
Make expanding after excessively cold at least partially of described thick liquid oxygen stream, and pass through and the rich argon steam stream indirect heat exchange be made up of described rich argon vapor overhead product, the described partly gasification and make described rich argon steam condensation at least partially making described thick liquid oxygen stream thus, to form described in rich argon liquid stream and described thick liquid oxygen stream liquid and gas at least partially;
A part for described rich argon liquid stream is discharged as argon product stream, and another part of described rich argon liquid stream is introduced in described argon column as argon column backflow stream; And
The liquid phase stream be made up of described thick liquid oxygen and gas phase stream are introduced in described lower pressure column respectively, and is formed and be introduced into described thick oxygen in described lower pressure column at least partially.
6. air separating method according to claim 1, wherein:
Described air pressure to be contractd purification, compress and the air stream purified to be formed;
Described compressed and a part for the air stream purified by cooling with described nitrogen enriched vapor stream indirect heat exchange, and be after this introduced in described higher pressure column;
By compressed described in compressing further and the another part of the air stream purified to form compressing and the air stream purified of boost pressure, oxygen enriched liquid stream described in pumping described at least partially to form the liquid stream of having pressurizeed, and by with described boost pressure compress and the air stream indirect heat exchange purified heat described in the liquid stream of having pressurizeed at least partially, to form described oxygen product stream, described oxygen product is produced thus from described liquid stream of having pressurizeed, and compressing and the generation liquid air stream at least partially of the air stream purified from described boost pressure, and
Described intermediate reflux stream forming at least partially by described liquid air stream.
7. air separating method according to claim 6, wherein, described thick liquid oxygen stream or described thick liquid oxygen stream and described intermediate reflux stream flow ground, indirectly exchanged heat to described liquid stream of having pressurizeed and at least described nitrogen enriched vapor stream and described liquid stream of having pressurizeed.
8. air separating method according to claim 2, wherein:
Described air pressure to be contractd purification, compress and the air stream purified to be formed;
Described compressed and a part for the air stream purified by cooling with described nitrogen enriched vapor stream indirect heat exchange, and be after this introduced in described higher pressure column;
By compressed described in compressing further and the another part of the air stream purified to form compressing and the air stream purified of boost pressure, oxygen enriched liquid stream described in pumping described at least partially with the liquid stream of having pressurizeed described in being formed, and by with described boost pressure compress and the air stream indirect heat exchange purified and the liquid stream of having pressurizeed described in heating at least partially, to form described oxygen product stream, described oxygen product is produced thus from described liquid stream of having pressurizeed, and compressing and the generation liquid air stream at least partially of the air stream purified from described boost pressure, and
Described intermediate reflux stream forming at least partially by described liquid air stream.
9. the air separating method according to claim 6 or 8, wherein:
Described in making boost pressure compress and the Part I of the air stream purified cools fully, and form described liquid air stream;
Described in making boost pressure compress and the Part II of the air stream purified partly cools, and introduce in turbo-expander, to form exhaust stream; And
Described exhaust stream is introduced in described higher pressure column and described lower pressure column, refrigeration is exerted in described cryogenic rectification process.
10. an air separation equipment, it comprises:
Air separation is equipped, and it is constructed by cryogenic rectification to be separated air, to produce at least oxygen product stream;
Described air separation equipment has destilling tower unit, one group of expansion valve and crosses cool-heat-exchanger, described destilling tower unit comprises higher pressure column and lower pressure column, described lower pressure column operably associates with heat transfer relation with described higher pressure column, and is constructed to receive at the place of higher position continuously of described lower pressure column thick oxygen, intermediate reflux stream and the rich nitrogen backflow stream that formed by the thick liquid oxygen stream of discharging from described higher pressure column at least partially;
Described expansion valve location makes described the decompression at least partially of described thick liquid oxygen stream, described intermediate reflux stream and described rich nitrogen backflow stream;
Described cool-heat-exchanger of crossing is positioned at the upstream of described expansion valve and is connected to described lower pressure column, to receive at least nitrogen enriched vapor stream from described lower pressure column; And
Described cross cool-heat-exchanger be constructed so that described thick liquid oxygen stream, described intermediate reflux stream and described nitrogen-rich liquid flow through with and flow ground, indirectly exchanged heat carry out indirect heat exchange at least nitrogen enriched vapor stream of described at least described nitrogen enriched vapor stream, described intermediate reflux stream and described nitrogen-rich liquid stream, and be excessively chilled to temperature lower continuously, and described intermediate reflux stream is chilled to described nitrogen-rich liquid stream excessively by the temperature crossed between the temperature of cold experience.
11. 1 kinds of air separation equipments, it comprises:
Air separation is equipped, and its structure is separated air by cryogenic rectification, at least to produce oxygen product stream from the liquid stream of having pressurizeed;
Described air separation equipment has destilling tower unit, one group of expansion valve and crosses cool-heat-exchanger, described destilling tower unit comprises higher pressure column and lower pressure column, described lower pressure column operably associates with heat transfer relation with described higher pressure column, and is configured to receive at the place of higher position continuously of described lower pressure column thick oxygen, intermediate reflux stream and the rich nitrogen backflow stream that formed by the thick liquid oxygen stream of discharging from described higher pressure column at least partially;
Described expansion valve location makes described the decompression at least partially of described thick liquid oxygen stream, described intermediate reflux stream and described rich nitrogen backflow stream;
Described cool-heat-exchanger of crossing is positioned at the upstream of described expansion valve and is connected to described lower pressure column, to receive at least nitrogen enriched vapor stream from described lower pressure column; And
Described cross cool-heat-exchanger be constructed so that described thick liquid oxygen stream, described intermediate reflux stream and described nitrogen-rich liquid flow through with and flow at least described nitrogen enriched vapor stream described in ground, indirectly exchanged heat to described liquid stream of having pressurizeed and described at least described nitrogen enriched vapor stream and described thick liquid oxygen stream or described thick liquid oxygen stream and described intermediate reflux stream and carry out indirect heat exchange, and be excessively chilled to the temperature reduced continuously.
12. air separation equipments according to claim 10, wherein, described cool-heat-exchanger excessively is also constructed so that described thick liquid oxygen stream is crossed and is as cold as another temperature, another temperature described is equal to or greater than the temperature of the described nitrogen-rich liquid stream before the described mistake of described nitrogen-rich liquid stream is cold, and is positioned at described intermediate reflux stream by the temperature range of the cold experience of mistake.
13. air separation equipments according to claim 12, wherein, described cool-heat-exchanger of crossing also is constructed so that described thick liquid oxygen stream is excessively cold from another temperature, and described another temperature is higher than the temperature of the described intermediate reflux stream before the described mistake of described intermediate reflux stream is cold.
14. air separation equipments according to claim 10 or 11, wherein:
Described destilling tower unit also has argon column;
Described argon column is connected to described lower pressure column, crude argon steam stream is obtained and rectifying described argon column from described lower pressure column, to produce rich argon vapor overhead product and containing oxygen column bottom product, and be introduced in described lower pressure column by the described oxygen stream that contains form containing oxygen column bottom product;
Argon condenser;
An expansion valve in described one group of expansion valve is positioned between described sub-cooling unit and described argon condenser, makes expanding after cold at least partially of described thick liquid oxygen stream;
Described argon condenser is connected to described argon column and described expansion valve, and be constructed so that described thick liquid oxygen stream at least partially through cold and through carrying out indirect heat exchange with the rich argon steam stream be made up of described rich argon vapor overhead product after expanding, described thick the described of liquid oxygen stream is made partly to gasify at least partially thus, and make described rich argon steam condensation, to form described in rich argon liquid stream and described thick liquid oxygen stream liquid and gas at least partially, a part for described rich argon liquid stream is discharged from described argon condenser to form argon product stream, and another part of described rich argon liquid stream is introduced described argon column from described argon condenser, as argon column backflow stream, and
Described argon condenser is connected to described lower pressure column, make the liquid phase stream that is made up of described liquid phase and described gas phase respectively and vapor phase stream be introduced in described lower pressure column, be introduced into described thick oxygen in described lower pressure column at least partially to be formed.
15. air separation equipments according to claim 10, wherein:
Described air separation equipment has: main heat exchanger; Main air compressor, with compressed air; Clean unit, it is connected to described main air compressor, with at described air by air described in the after-purification compressed, and formed thus and compressed and the air stream purified; And booster compressor, it is connected to described clean unit, has compressed further and the air stream purified to be formed;
Described main heat exchanger is connected between described clean unit and described higher pressure column, and to compress described in being constructed so that and a part for the air stream purified is cooled by carrying out indirect heat exchange with described nitrogen enriched vapor stream, and be introduced in described higher pressure column;
Pump is connected to described destilling tower unit and carrys out at least partially described of oxygen enriched liquid stream described in pumping, to form the liquid stream of having pressurizeed, and described main heat exchanger is connected to described booster compressor, and structure by with described boost pressure compress and the air stream purified carry out indirect heat exchange to heat described in the liquid stream of having pressurizeed at least partially, described oxygen product is produced thus from described liquid stream of having pressurizeed, and compressing and the generation liquid air stream at least partially of the air stream purified from described boost pressure; And
Described main heat exchanger and described lower pressure column and another expansion valve in being positioned between described sub-cooling unit and described lower pressure column described one group of expansion valve become to flow and are communicated with, make described liquid air stream at least partially described cross excessivelys cold in cool-heat-exchanger, expand and be introduced in described lower pressure column, and form the described intermediate liquid backflow containing oxygen and nitrogen thus and flow.
16. air separation equipments according to claim 15, wherein, described cool-heat-exchanger of crossing is connected between described lower pressure column and described main heat exchanger, and is constructed so that described thick liquid oxygen stream or described thick liquid oxygen stream and described intermediate reflux stream and flows ground, indirectly exchanged heat to described liquid stream of having pressurizeed and at least described nitrogen enriched vapor stream.
17. air separation equipments according to claim 11, wherein:
Described air separation equipment has: main heat exchanger; Main air compressor, with compressed air; Clean unit, it is connected to described main air compressor, with at described air by air described in the after-purification compressed, and formed thus and compressed and the air stream purified; And booster compressor, it is connected to described clean unit, has compressed further and the air stream purified to be formed;
Described main heat exchanger is connected between described clean unit and described higher pressure column, and to compress described in being constructed so that and a part for the air stream purified cools by carrying out indirect heat exchange with described nitrogen enriched vapor stream, and be introduced in described higher pressure column;
Pump is connected to described destilling tower unit and carrys out at least partially described of oxygen enriched liquid stream described in pumping, with the liquid stream of having pressurizeed described in being formed, and described main heat exchanger is connected to described booster compressor, and be constructed by with described boost pressure compress and the air stream purified carry out indirect heat exchange to heat described in the liquid stream of having pressurizeed at least partially, described oxygen product is produced thus from described liquid stream of having pressurizeed, and compressing and the generation liquid air stream at least partially of the air stream purified from described boost pressure, and
Described main heat exchanger and described lower pressure column and another expansion valve of described one group of expansion valve be positioned between described sub-cooling unit and described lower pressure column become to flow and are communicated with, make described liquid air stream excessively cold in described heat exchanger at least partially, expand and be introduced in described lower pressure column, and formed thus described intermediate liquid backflow stream.
18. air separation equipments according to claim 15 or 17, wherein:
Described air separation equipment has turbo-expander, described turbo-expander is connected to one in described lower pressure column and described higher pressure column, in described one that makes the exhaust stream produced by described turbo-expander be introduced in described lower pressure column and described higher pressure column, refrigeration is exerted in described air separation equipment; And
Described in described main heat exchanger is constructed so that boost pressure compress and the Part I of the air stream purified is completely cooled and forms described liquid air stream, and described boost pressure compress and the Part II of the air stream purified is already partially cooled and discharges from described main heat exchanger; And
Described turbo-expander is connected to described main heat exchanger, described in making boost pressure compress and the described Part II of the air stream purified expands in described turbo-expander, to produce described exhaust stream.
CN201280049443.9A 2011-10-07 2012-09-21 Air separation method and apparatus Pending CN104685310A (en)

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