CN104204699A - Process for the separation of air by cryogenic distillation - Google Patents

Process for the separation of air by cryogenic distillation Download PDF

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Publication number
CN104204699A
CN104204699A CN201380015981.0A CN201380015981A CN104204699A CN 104204699 A CN104204699 A CN 104204699A CN 201380015981 A CN201380015981 A CN 201380015981A CN 104204699 A CN104204699 A CN 104204699A
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CN
China
Prior art keywords
heat exchanger
stream
temperature
oxygen
cooling
Prior art date
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Pending
Application number
CN201380015981.0A
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Chinese (zh)
Inventor
B·哈
J-R·布吕格罗勒
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LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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Publication of CN104204699A publication Critical patent/CN104204699A/en
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04048—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of cold gaseous streams, e.g. intermediate or oxygen enriched (waste) streams
    • F25J3/04054—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of cold gaseous streams, e.g. intermediate or oxygen enriched (waste) streams of air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—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
    • F25J3/04163—Hot end purification of the feed air
    • F25J3/04169—Hot end purification of the feed air by adsorption of the impurities
    • F25J3/04175—Hot end purification of the feed air by adsorption of the impurities at a pressure of substantially more than the highest 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
    • F25J3/04296—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.
    • F25J3/04393—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
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/10—Mathematical formulae, modeling, plot or curves; Design methods

Abstract

A process for separation of air by cryogenic distillation, including cooling a first purified feed air stream in a heat exchanger, thereby producing a cooled first feed stream, removing a first portion from the heat exchanger at a first intermediate temperature, and compressing the cooled first portion in a first booster compressor, cooling the compressed first portion in the heat exchanger, thereby producing a cooled first portion, removing a second portion from the heat exchanger at a second intermediate temperature, and compressing the cooled second portion in a second booster compressor, cooling the compressed second portion in the heat exchanger, thereby producing a cooled second portion, and vaporizing a pressurized liquid stream from the column system in the heat exchanger at a vaporization temperature to form a pressurized gaseous product stream, wherein, both the first discharge temperature and said second discharge temperature are below -55 DEG C.

Description

By the method for separating air by cryogenic distillation
Technical field
The present invention relates to a kind of for by the method and apparatus of separating air by cryogenic distillation.
Background technology
Hereinafter, " gasification " should be considered to cover the standard gasification of supercritical liq, and " gasification temperature " should be considered to cover the inflection temperature of supercritical liq in the time that its concentration reduces.
For impure liquid, gasification temperature will can not be single temperature, and therefore this term refers to the mean temperature scope of liquid gasification.
By known cold compression method in the field of separating air by cryogenic distillation.Conventionally, in air-separating plant, the object of cold compression can be divided three classes:
1. in order to improve performance or the cost benefit of liquid oxygen pumped method.This improvement realizes by the liquid oxygen gasification portion section of the compression heat of cold compression being injected to heat exchanger.New invention has solved the improvement of the method in this classification.
2. in order to improve the distillation performance of air separation equipment.The heat pump cycle being driven by cold compressor/cryogenic compressor is the typical case of such cold compression plant.
3. for the surplus of the refrigerating capacity being provided by the external source of liquid supply is provided.
But, as US-A-5475980, US-A-5966967 and the single cold compressor method of describing in US-A-5901576 compared with using the best equipment of main air compressor and the combination (MAC+BAC) of booster air compressor at the low about 3-5% of efficiency aspect the detachment dynamic of oxygen.According to definition, the detachment dynamic of oxygen deducts product N by the feed air compressing from atmospheric pressure to the compression energy of required pressure by using 2, O 2obtain Deng the pressure energy with respect to atmospheric pressure.Because the distillation performance of two kinds of methods is similar, the poor efficiency of cold compressor method can be owing to the irreversibility or the poor efficiency that are associated with the enforcement of cold compression.
Fig. 3 in US-A-6962062 and 4 shows the cold compressor that uses two series connection with the method for the performance of improving one's methods.The operating temperature of the cold compressor of higher temperatures is more much higher than the gasification temperature of liquid oxygen, and in the time running into high hot-side temperature, uses this cold compressor to be suitable for.The heat of compression of the cold compressor of higher temperatures does not help the gasification of liquid oxygen.Only have the cold compressor of single lower temperature to work in the temperature range that approaches liquid oxygen gasification temperature and its heat of compression is injected into interchanger to improve the gasification of oxygen.
In US-A-7272954, outside cryogenic fluid source is admitted to Distallation systm so that refrigeration to be provided, and suggestion is compressed to elevated pressures for the follow-up liquefaction in main switch by the cold compressor of two series connection by feed air low temperature.Preferably produce the external source of liquid in the low period of power cost.Then, the gained liquia air forming by air liquefaction be admitted to Distallation systm with produce liquid oxygen, this liquid oxygen be pumped subsequently and gasify paramount pressure with form gaseous oxygen product.This method also has some shortcomings:
1. need outer liquid body source.
2. feed air is substantially under the pressure of the high-pressure tower in Distallation systm, and the cold compressor in this arrangement, by the quite high compression ratio of needs, therefore needs multiple levels.
3. because the pressure of feed air is low, can not be cost-saving for the size reduction of the front end clean unit (FEP) of removing moisture and carbon dioxide.
Therefore, need a kind of use that the method and apparatus of the cold compression of improved power consumption is provided.
Summary of the invention
The present invention relates to a kind of at least one equipment and method meeting in these needs.Some embodiment of the present invention relates to a kind of method that uses at least two cryogenic compressors (cold compressor, cold compressor) of arranged in series to improve the power consumption in such method.In certain embodiments, cryogenic compressor operates near making from the boiling point of the liquid gasification of destilling tower or inflection temperature.In another embodiment, the one or more strands of forced airs stream that leaves heat exchanger expanded before entering lower pressure column, high-pressure tower or their combination.
In another embodiment, provide a kind of for by the method for separating air by cryogenic distillation.In this embodiment, be included in cooling the first purification feed air stream in heat exchanger, thereby produce through the first cooling feed streams, under the first medium temperature, shift out Part I from heat exchanger, and in the first booster compressor, compress described through cooling Part I, cooling compressed Part I in heat exchanger, produce thus through cooling Part I, under the second medium temperature, shift out at least a portion through cooling Part I from heat exchanger, and in the second booster compressor, compress the described part being moved out of through cooling Part I to form compressed Part II, cooling described compressed Part II in heat exchanger, produce thus through cooling Part II, and in heat exchanger, gasification is flowed to form pressurized gaseous product from the pressurized liquid stream of Tower System under gasification temperature, wherein, described the first exhaust temperature and described the second exhaust temperature are both lower than-55 DEG C.
Brief description of the drawings
Fig. 1 show according to prior art conventionally approximately 30 to gasifying liquid oxygen and as the heat exchange chart between the air of heat medium under the pressure of 80bar.
Fig. 2 shows in the situation of two cryogenic compressors with series connection according to an embodiment of the invention, conventionally approximately 30 to gasifying liquid oxygen and as the heat exchange chart between the air of heat medium under the pressure of 80bar.
Fig. 3 shows schematic diagram according to an embodiment of the invention.
Detailed description of the invention
Illustrative examples of the present invention is described below.Although the various amendments of tolerable of the present invention and alternative form, its specific embodiment illustrates by way of example in the accompanying drawings and describes in detail in this article.But, be to be understood that, specific embodiment description is herein not intended to limit the invention to particular forms disclosed, but contrary, its intention is to contain all modifications, equivalent and the replacement scheme that fall in the spirit and scope of the present invention that limited by claims.
Can certainly understand, in the exploitation of any this actual embodiment, must formulate numerous embodiments---specifically determine, to realize developer's specific objective, for example meet with business relevant constraint relevant to system, this will change between different embodiments.In addition, it should be understood that this development effort may be complicated and time-consuming, but be to have to those skilled in the art the program that benefit of the present invention is carried out.
There are some advantages compared with traditional liquid pumping method according to the method for some embodiment of the present invention:
There is single main air compressor (MAC): this simplified compression be and reduced equipment cost because no longer need booster air compressor (BAC).
The blowdown presssure of this MAC is in the scope of 10 to 20bar abs, or 14 and 20barabs between, make the quite compactness of size for removing the required front end clean unit of moisture and carbon dioxide (FEP or mol sieve unit), thereby significantly reduce costs.
By move MAC under such high pressure, can cancel for FEP's cooler or cooling tower.The reliability that this has also significantly reduced cost and has improved equipment.
In particular, the present invention relates to a kind ofly for produce the method and apparatus of gaseous oxygen under pressure, wherein used the cryogenic compressor of two series connection to compress feed air.Cryogenic compressor under this particular case is considered to the compressor of inlet temperature between-60 DEG C and-170 DEG C.
Fig. 1 show according to prior art conventionally approximately 30 to gasify under the pressure of 80bar liquid oxygen and as the air of heat medium between carry out heat exchange chart.Relation between heat exchange and oxygen temperature is illustrated as continuous line, and the relation between heat exchange and air themperature is illustrated as dotted line.Carry out compressed air stream 101 so that liquid oxygen stream 102 gasifies with single cryogenic compressor 103 in this example.Can find out, the cold air of the temperature in high about 2 to 5 DEG C of the inflection temperature than in the supercritical pressure situation of the boiling point of gasification liquid oxygen or gasification liquid oxygen enters cryogenic compressor and is compressed to higher pressure.Compressed-air actuated temperature is because the heat of compression becomes higher, but still in cryogenic conditions.Then, this air carries out heat exchange and is cooled with gasification oxygen in interchanger.Because this curvature is almost similar to the heating curves of oxygen because the step that phase transformation produces changes, the temperature difference therefore as far as possible reducing in heat exchanger at those temperature levels is quite difficult.The large temperature difference means high irreversibility or poor efficiency.The compressed-air actuated cooling slope that causes air cooling curve changes, and makes this heating curves can follow the tracks of cooling curve, but the linear cooling curve of air heating and gasifying liquid effectively.
Fig. 2 has described identical application, but uses according to one embodiment of present invention two cryogenic compressors of series connection instead of one.Compressed air stream 201 in the first cryogenic compressor 203.The outlet air of discharging the first cryogenic compressor 203 is cooled and enters the second compressor 204 and arrives higher pressure with further low temperature compression.The exhaust of the second compressor is cooling in interchanger and liquefaction subsequently.In one embodiment, the operation inlet temperature of two cryogenic compressors can be chosen to than high approximately 2 to 5 DEG C of the gasification boiling point of oxygen 202 or inflection temperature.Can find out, by twice, compressed air is delivered to gasification portion section, the slope of the cooling curve of air can significantly change, thereby follows the tracks of better the heating curves of oxygen.In addition,, by using this intercooled two cryogenic compressors that have, the compression ratio of cryogenic compressor reduces and can obtain less temperature rise.This has further improved the efficiency of heat exchange chart and compression method.
Referring now to Fig. 3,, be preferably introduced in heat exchanger 490 from the liquid stream 471 of low temperature distillation process, wherein, this liquid stream is gasificated into pressurized gaseous product stream 472.The purified air stream 401 that can be compressed purified air stream can be divided into the first purified air stream 402, the second purified air stream 435 and the 3rd purified air stream 408.
Can be in high temperature compressed machine (warm compressor) 484 further supercharging first to purify feed air stream 402 cooling in heat exchanger 490, produce thus through the first cooling feed streams 453.This Part I 403 through the first cooling feed streams 453 shifts out from the mid portion of heat exchanger 490 under the first medium temperature, and compressed in the first cryogenic compressor 482.Compressed Part I 404 in the first exhaust temperature is cooling in heat exchanger 490 subsequently, produces thus through cooling Part I 451.A part 474 through cooling Part I 451 shifts out from the mid portion of heat exchanger 490 under the second medium temperature, and compressed in the second cryogenic compressor 485.
Compressed Part II 475 under the second exhaust temperature is cooling in heat exchanger 490, produces thus through cooling Part II 450.Described the first exhaust temperature and the second exhaust temperature are both lower than-55 DEG C.
Through the first cooling feed streams 453, can combine to form liquefied air stream 455 through cooling Part I 451 with through cooling Part II 450, be then sent to the first destilling tower 500.
Liquid stream 471 can be for example, subcritical pressurized liquid stream from Tower System (, 500 and 502).So, described the first medium temperature and the second medium temperature can differ and be less than 10 DEG C with gasification temperature, or are preferably less than 5 DEG C.
Liquid stream 471 can be the overcritical pressurized liquid stream from Tower System.So, described the first medium temperature and the second medium temperature can differ and be less than 10 DEG C with inflection temperature, or are preferably less than 5 DEG C.
In one embodiment, the 3rd purified air stream 408 is cooling in heat exchanger 490, can at the temperature lower than described the first medium temperature and the second medium temperature, shift out from heat exchanger 490 through the 3rd cooling feed air stream 429.Can be sent to the first turbo-expander 486 through the 3rd cooling feed air stream 429, the second feed air stream that then at least a portion expands is sent to the first destilling tower 500.The first destilling tower 500 can be medium pressure column.
Second purifies feed air stream 435 can be cooling in heat exchanger 490, shifts out, and be sent to the second turbo-expander 481 at the temperature lower than described the first medium temperature and the second medium temperature as stream 433 from heat exchanger 490.At least a portion of stream 434 air streams that expand can be introduced into after-fractionating tower 502.
Purified air stream 401 can 15 and 20bar abs between.The liquefied air stream 455 that enters the first destilling tower 500 comprises the stream obtaining from the Part I 451 through cooling with through the first cooling feed streams 453.Pressurized liquid stream 471 can 30bar abs at least, preferably at least 60bar abs, more preferably at least under the pressure of 80bar abs, be vaporized.
In one embodiment, be sent to the first destilling tower 500, after-fractionating tower 502 or heat exchanger 490 without any the liquid storing.In one embodiment, produce by the first turbo-expander 486 and the second turbo-expander 481 for whole refrigerating capacitys of distilling.The 3rd purified air stream 408 is can be in heat exchanger 490 cooling to produce stream 452 and to be sent to before the first destilling tower 500 with the first feed streams 453 through cooling, through cooling Part I 451 and the one or more combinations in cooling Part II 450.
The 3rd purified air stream 408 and the second purified air stream 435 are depicted as stream separately, so that described method easily understands, but can certainly be combined as single stream.
example
In order to prove neoteric efficiency, the method is used for simulation and produces the oxygen equipment of 95% the low-purity gaseous oxygen by volume of 80bar.Do not produce pressurization nitrogen.Fig. 3 shows the method.
Described method is used a main heat exchanger 490 and has by the hot linked high-pressure tower 500 of bottom reboiler of lower pressure column bottom and the double tower of lower pressure column 502.
The purification feed air stream 401 in about 10.6bar from single main air compressor (not shown) is sent to main heat exchanger 490.A part 402 for this air is further compressed to produce the first compressive flow 406 of about 16bar in high temperature compressed machine 484, and this first compressive flow is cooled to the low temperature of approximately-109 DEG C in main heat exchanger 490.The Part I 403 of this cooling-air subsequently in the first cryogenic compressor 482 by low temperature compression to form compressed Part I 404 in 31bar.Then, compressed Part I 404 is cooling to form through the second cooling compressive flow in main heat exchanger 490, its part, part 474 in second cryogenic compressor 485 of inlet temperature with approximately-109 DEG C further by low temperature compression to form the compressed Part II 475 in 60bar.Then, this stream is cooled to through cooling Part II 450, and expands and liquefaction before being supplied to Tower System as a part for liquefied air stream 455.
A part for the first compressive flow 406 is not sent to the first cryogenic compressor 482, but quilt is completely cooling to form through the first cooling feed streams 453 in main heat exchanger 490, expands and be sent to the first destilling tower 500 as liquefied air stream 455 in valve.
Be not sent to the second cryogenic compressor 485 from a compressed-air actuated part for the first cryogenic compressor 482, but in heat exchanger, be cooled to lead to cold junction through cooling Part I 451, in valve, expand and be sent to the first destilling tower 500 as liquefied air stream 455.
The 3rd purified air stream 408 is sent to described interchanger under 10.6bar, is cooled to the temperature lower than the inlet temperature of cryogenic compressor 482,485 and is divided into two parts.Be sent to the first turbo-expander 486 through the 3rd cooling feed air stream 429, and gaseous state feed 430 is sent to the bottom of high-pressure tower 500.The remainder of the 3rd purified air stream 408 is fully cooling to form stream 452, expand and to be sent to high-pressure tower 500 as a part for liquefied air stream 455 in heat exchanger 490.
The second purified air stream 435 is cooling in described interchanger under 10.6bar pressure, is cooled to the temperature lower than the inlet temperature of cryogenic compressor 482,485 and is all delivered to the second turbo-expander 481 as stream 433.The stream 434 expanding is sent to lower pressure column 502.
Extract oxygen enriched liquid 470 from the bottom of lower pressure column 502, be forced into about 80bar and in heat exchanger 490, gasify to form gaseous state pressurised oxygen 472 by pump 483.
Gaseous nitrogen from the top of lower pressure column is heated to form gaseous nitrogen stream 422 in heat exchanger 490.
Oxygen-rich stream 410, intermediate flow 413 and nitrogen-enriched stream 414 all shift out, expand and are sent to lower pressure column 502 from high-pressure tower 500 with liquid form.
Turbo-expander 481 and 486 can be arranged to drive the first cryogenic compressor 482, the second cryogenic compressor 485 and/or high temperature compressed machine 484.Decompressor can be divided into the different decompressors that move with paralleling model and drive booster.In addition, also can drive one or more boosters with electro-motor, this can reduce the quantity of decompressor.
By using formula: [flow × 0.1 × log (P 2/ P 1)] estimate that described stream is in pressure P 2under with respect in pressure P 1under energy, can realize 0.3kWh/Nm by the method 3separation energy.The efficiency obtaining is goodish, is similar to the efficiency of mixing column method.Owing to not producing nitrogen, the method can be applicable to easily by extracting N from high-pressure tower 500 2produce N 2(stream 443).When producing N 2time, the flow of the second turbo-expander 481 must reduce, and the air pressure of purified air stream 401 can raise with the reduction of compensate for dilatation device flow.
Can see, except forming liquid by the cooling air from the second cryogenic compressor, can under some pressure, extract about 131Nm from interchanger altogether 3the liquid air of/h is to raise the efficiency: extract stream 452 at 10.4bar, extract through the first cooling feed streams 453 at 15.8bar, extract through cooling Part I 451 at 30.4bar.This represents the flow almost identical with the flow of the second cryogenic compressor.Because this flow of liquefied air is not compressed by the second cryogenic compressor, can obtain significant power and save.
Such method also can be used for producing with good efficiency the air gas separation unit of argon.
It should be understood that the present invention is also applicable to the situation of multiple fluid under pressure, one of wherein said fluid under pressure is nitrogen-rich liquid.
Depend on the pressure of (one or more) pressurized stream and treat the amount of the liquid form product of being produced by air separation equipment, from the pressure of the main air flow of air compressor can 10 and 20bar between, preferably 11 and 15bar between.
Although the present invention is described in conjunction with its specific embodiment, it is evident that, according to aforementioned description, manyly substitute, modifications and variations will be apparent for a person skilled in the art.Therefore, the invention is intended to allly such substituting, within amendment and modification be included in the spirit and scope of claims.The present invention can suitably comprise, comprise or mainly comprise disclosed key element, and can in the situation that not there is not undocumented key element, implement.In addition,, if there is the language of for example first and second order of instruction, should be understood to exemplary meaning instead of restrictive.For example, those skilled in the art will recognize that some step can be combined into one step.
Singulative " one ", " one " and " being somebody's turn to do " comprise that plural number refers to, unless context separately has clearly regulation.
Be open transitional term " the comprising " in claim, and it refers to that it is the display (, within any other can additionally comprise and remain on the scope of " comprising ") of a nonexcludability that established right subsequently requires element." comprising " used herein can be by having more restrictive transitional term " substantially by ... composition " and " by ... composition " is alternative, unless separately indicated herein.
" providing " in claim be defined as assignment standby, supply with, make available or prepare something or other.When described step can not have the Explicit Language contrary with represented scope in the claims, carry out by anyone, be understood that another embodiment is from described embodiment.
Optionally or optionally refer to that event or the situation described subsequently may or may not can occur.This description comprises the situation that event or situation occur and situation about not occurring.
Scope can be expressed as in this article from an about particular value and/or to about another particular value.During when such particular value and/or to another particular value, comprise the whole combinations in described scope.
All bibliography of listing herein separately by reference entirety be incorporated to the application, and quote each bibliography for customizing messages.

Claims (21)

1. for separate a method for air by carrying out low temperature distillation with heat exchanger, the Tower System that comprises lower pressure column and high-pressure tower, the method comprises the steps:
A) in heat exchanger, cooling and purifying air stream flows to produce liquefied air, described heat exchanger has hot junction, cold junction and mid portion, wherein said purified air stream is under the remarkable higher pressure than high-pressure tower, and described liquefied air flows in the time leaving the cold junction of heat exchanger in temperature T c;
B) liquefied air stream is introduced to described Tower System under the cryogenic conditions that is configured to come by the low temperature distillation in described Tower System production oxygen-rich stream and nitrogen-enriched stream;
C) extract described oxygen-rich stream from described Tower System, and use pump to pressurize to produce pressurization oxygen-rich stream to described oxygen rich stream;
D) described pressurization oxygen-rich stream is caused to the cold junction of heat exchanger; With
E) gasify described pressurization oxygen-rich stream to produce gaseous oxygen product stream in the hot junction of heat exchanger,
Wherein, step is a) further comprising the steps of:
I) shift out the Part I of described purified air stream and the first cryogenic compressor, compress this Part I to form the Part I of supercharging from the described mid portion of heat exchanger, wherein said Part I in the time leaving described mid portion in temperature T i;
Ii) in heat exchanger the Part I of cooling described supercharging with form through cooling Part I;
Iii) from the described mid portion of heat exchanger shift out described compress through cooling Part I and the second cryogenic compressor described through cooling Part I to form the Part II of supercharging, wherein, described through cooling Part I in the time leaving described mid portion in temperature T ii; With
Iv) in heat exchanger, the Part II of cooling described supercharging flows to form liquefied air,
Wherein, described the first cryogenic compressor moves near the gasification temperature of gasification oxygen;
Wherein step is b) further comprising the steps of:
I) in temperature T 2under shift out the Part II of described purified air stream and use subsequently the first turbo-expander to make this Part II expand to form the Part II of expansion from the described mid portion of heat exchanger;
Ii) Part II of described expansion is caused to the lower pressure column of Tower System;
Iii) in temperature T 3under shift out the Part III of described purified air stream and use subsequently the second turbo-expander to make this Part III expand to form the Part III of expansion from the described mid portion of heat exchanger; And
Iv) Part III of described expansion is caused to the high-pressure tower of described Tower System.
2. according to the method described in claim 0, wherein, described purified air stream is under the absolute pressure between about 10bar and about 20bar.
3. according to the method described in claim 0, wherein, described purified air stream is under the absolute pressure between about 14bar and about 20bar.
4. according to the method described in claim 0, wherein, T 2compare T iand T iilow.
5. according to the method described in claim 0, wherein, T 3compare T iand T iilow.
6. for separate a method for air by carrying out low temperature distillation with heat exchanger, the Tower System that comprises lower pressure column and high-pressure tower, the method comprises the steps:
A) in heat exchanger, cooling and purifying air stream flows to produce liquefied air, described heat exchanger has hot junction, cold junction and mid portion, wherein said purified air stream is in the pressure higher than described high-pressure tower, and wherein said liquefied air flows in the time leaving the cold junction of heat exchanger in temperature T c;
B) described liquefied air stream is introduced to described Tower System under the cryogenic conditions that is configured to come by the low temperature distillation in described Tower System production oxygen-rich stream and nitrogen-enriched stream;
C) extract oxygen-rich stream from described Tower System, and use pump to pressurize to produce pressurization oxygen-rich stream to described oxygen rich stream;
D) described pressurization oxygen-rich stream is caused to the cold junction of heat exchanger; With
E) gasify described pressurization oxygen-rich stream with the hot junction generation gaseous oxygen product stream at heat exchanger, wherein said pressurization oxygen-rich stream provides at least a portion refrigerating capacity to carry out cooling described purified air stream,
Wherein, step is a) further comprising the steps of:
I) shift out the Part I of described purified air stream and the first cryogenic compressor, compress described Part I to form the Part I of supercharging from the described mid portion of heat exchanger, wherein said Part I in the time leaving described mid portion in temperature T i;
Ii) in heat exchanger the Part I of cooling described supercharging with form through cooling Part I;
Iii) from the described mid portion of heat exchanger shift out described compress through cooling Part I and the second cryogenic compressor described through cooling Part I to form the Part II of supercharging, wherein, described through cooling Part I in the time leaving described mid portion in temperature T ii; With
Iv) in heat exchanger, the Part II of cooling described supercharging flows to form described liquefied air,
Wherein T iand T iibe roughly the same and compare T chigh temperature.
7. method according to claim 6, wherein said the first cryogenic compressor and described the second cryogenic compressor move near the gasification temperature of gasification oxygen.
8. method according to claim 6, wherein said the first cryogenic compressor and described the second cryogenic compressor move in the scope of approximately 10 DEG C of the gasification temperature of gasification oxygen.
9. method according to claim 6, wherein said the first cryogenic compressor and described the second cryogenic compressor move in the scope of approximately 5 DEG C of the gasification temperature of gasification oxygen.
10. method according to claim 6, wherein T iand T iilower than approximately-55 DEG C.
11. methods according to claim 6, wherein said purified air stream before being just cooled in heat exchanger under ambient temperature conditions.
12. methods according to claim 6, further comprising the steps of:
In temperature T 2under shift out the Part II of described purified air stream from the described mid portion of heat exchanger, then use the first turbo-expander to make this Part II expand to form the Part II of expansion; With
The Part II of described expansion is caused to the lower pressure column of described Tower System.
13. method according to claim 12, wherein T 2compare T iand T iilow.
14. methods according to claim 6, further comprising the steps of:
In temperature T 3under shift out the Part III of described purified air stream from the described mid portion of heat exchanger, then use the second turbo-expander to make this Part III expand to form the Part III of expansion; With
The Part III of described expansion is caused to the high-pressure tower of described Tower System.
15. method according to claim 14, wherein T 3compare T iand T iilow.
16. methods according to claim 6, are also included in step and a) in high temperature pressurised device, compress before described purified air stream.
17. methods according to claim 6, wherein said purified air stream is under the absolute pressure between about 10bar and about 20bar.
18. methods according to claim 6, under the pressure of wherein said pressurization oxygen-rich stream in 50bar abs at least.
19. methods according to claim 6, under the pressure of wherein said pressurization oxygen-rich stream in 60bar abs at least.
20. methods according to claim 6, under the pressure of wherein said pressurization oxygen-rich stream in 70bar abs at least.
21. methods according to claim 6, the heat of compression of wherein said the first cryogenic compressor and described the second cryogenic compressor described pressurization oxygen-rich stream that contributes to gasify.
CN201380015981.0A 2012-03-29 2013-03-27 Process for the separation of air by cryogenic distillation Pending CN104204699A (en)

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