CN102506559A - Air-separation process for preparing high-purity nitrogen by multi-segment rectification - Google Patents

Air-separation process for preparing high-purity nitrogen by multi-segment rectification Download PDF

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CN102506559A
CN102506559A CN2011103019576A CN201110301957A CN102506559A CN 102506559 A CN102506559 A CN 102506559A CN 2011103019576 A CN2011103019576 A CN 2011103019576A CN 201110301957 A CN201110301957 A CN 201110301957A CN 102506559 A CN102506559 A CN 102506559A
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nitrogen
air
rectifying column
rectifying
liquid nitrogen
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曹钧
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KAIFENG DONGJING AIR SEPARATION GROUP CO Ltd
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KAIFENG DONGJING AIR SEPARATION GROUP CO Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—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
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/04084—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04151—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
    • F25J3/04193—Division of the main heat exchange line in consecutive sections having different functions
    • F25J3/04206—Division of the main heat exchange line in consecutive sections having different functions including a so-called "auxiliary vaporiser" for vaporising and producing a gaseous product
    • 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
    • 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
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04812—Different modes, i.e. "runs" of operation
    • F25J3/04824—Stopping of the process, e.g. defrosting or deriming; Back-up procedures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/50—Processes or apparatus using separation by rectification using multiple (re-)boiler-condensers at different heights of the column
    • F25J2200/54—Processes or apparatus using separation by rectification using multiple (re-)boiler-condensers at different heights of the column in the low pressure column of a double pressure main column system
    • 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
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/42—Processes or apparatus involving steps for recycling of process streams the recycled stream being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/30—External or auxiliary boiler-condenser in general, e.g. without a specified fluid or one fluid is not a primary air component or an intermediate fluid
    • F25J2250/40—One fluid being air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/30—External or auxiliary boiler-condenser in general, e.g. without a specified fluid or one fluid is not a primary air component or an intermediate fluid
    • F25J2250/42—One fluid being nitrogen

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

Abstract

The invention discloses an air-separation process for preparing high-purity nitrogen by multi-segment rectification. The air-separation process mainly utilizes a low-temperature method and adopts multi-segment rectification, isentropic expansion refrigeration cycle and partial high-purity nitrogen products with evaporators to realize internal compression. The air-separation process is characterized in that nitrogen products with different output pressures can be prepared by segment, the separation work in the rectification process is reasonably distributed, namely the irreversible loss in the nitrogen-preparing process is effectively reduced, and the utilizable useful work in the process flow can be fully utilized and is converted into the needed refrigerating capacity in the nitrogen-preparing process flow, so that the yield of liquid-nitrogen products is increased. By adoption of the air-separation process, not only can the internal compression of partial nitrogen products be realized, but also the high-purity products with two or more pressure grades such high-pressure nitrogen and medium-pressure nitrogen and the like can be provided due to addition of the flow distribution of the evaporator. According to the air-separation process, not only is the flow reasonable, but also the energy-saving effect is obvious, namely the unit nitrogen-preparing energy consumption is effectively reduced and is about 0.2164KW.h/Nm<3>N2, and the nitrogen extraction rate is up to 71%, so that the performance of high-purity nitrogen equipment is greatly improved.

Description

The high pure nitrogen space division technique is produced in multistage rectifying
Technical field
The present invention relates to a kind of low temperature process and produce the space division technique of high pure nitrogen, particularly the high pure nitrogen space division technique is produced in multistage rectifying.It is applicable to that low temperature process produces the high pure nitrogen industry.
Background technology
At present; It is to adopt single-stage rectifying mostly that low temperature process is produced the high pure nitrogen industry; The technology of the drag flow or the constant entropy expansion kind of refrigeration cycle of backflowing is produced high pure nitrogen; Characteristics such as though this nitrogen producing craft has simple flow, device cartridge list and quantity is few, floor space is little, simple to operate, stable, nitrogen product quality height.But the space division technique that high pure nitrogen is produced in single-stage rectifying has the wasted work of separation big, the inherent shortcoming that energy consumption is high.Specific energy consumption is at 0.30-0.37KW.h/Nm 3N 2, the nitrogen product recovery rate is low, be merely between the 37-45%, and it is single to produce product, only can a kind of pressure rating nitrogen product of output, and liquid nitrogen product output is less in addition.
In recent years, the space division technique that a kind of two sections rectifying, drag flow constant entropy expansion kind of refrigeration cycle are produced high pure nitrogen has abroad appearred.Though this technology can improve the recovery rate of nitrogen product, reduce the specific energy consumption of nitrogen product, make specific energy consumption can reach 0.25KW.h/Nm 3N 2About, and the high pure nitrogen product of two kinds of different pressures grades of the ability middle and high pressure of output, thereby make the performance of equipment obtain very significantly promoting.But if along with the requirement of the output pressure of user's centering, high pressure high pure nitrogen product when higher, a large amount of useful work can not make full use of, and irreversible loss also can strengthen.When the output pressure of middle and high pressure high pure nitrogen product was high more, above-mentioned phenomenon was just more outstanding.Therefore; Need product nitrogen gas is adopted the method for external compression, can alleviate described outstanding problem, equipment increase, investment increase, external compression lectotype selection difficulty but this has brought again; Product nitrogen gas pressurization back is polluted because of pressure process its purity is reduced, and is difficult to satisfy user's drawbacks such as requirement.
Summary of the invention
The object of the present invention is to provide a kind of multistage rectifying to produce the high pure nitrogen space division technique; It can overcome the deficiency of prior art; Can reduce the irreversible loss of producing in the high pure nitrogen space division technique flow process effectively, can utilize useful work fully, and make it to be converted into and produce the required cold of high pure nitrogen space division technique flow process; Thereby can increase the output of liquid nitrogen product, can necessary condition be provided for compression in the part nitrogen product again; And can make energy consumption index reduction, good energy-conserving effect, product quality is high.
Technological process of the present invention comprises following processing step:
< 1>air is through making it to become dry compressed air after the compressor compresses and after precooling, purification system carry out preliminary treatment; This dry compressed air is sent in the main heat exchanger of distillation system and is carried out heat exchange with the cool gas that backflows; And compressed air self that should drying is able to cooling; Cooled part compressed air is sent to the 1# decompressor and is carried out constant entropy expansion, and the part cold of generation gets into goes up rectifying column participation rectifying, realizes first order drag flow constant entropy expansion kind of refrigeration cycle.
< 2>the remaining dried compressed air in the said main heat exchanger is further cooled off, and in this main heat exchanger, is cooled to saturation temperature, the further heat exchange of liquid nitrogen after delivering to evaporimeter and pressurizeing; Deliver to down rectifying column after the heat exchange and participate in rectifying; In following rectifying column distillation process, following rectifying column top has produced high pure nitrogen, the oxygen-enriched liquid air heat exchange in the 1# condenser/evaporator of this high pure nitrogen and last rectifier bottoms and form liquid nitrogen; Liquid nitrogen behind the partial liquefaction is participated in rectifying column rectifying down as phegma; Another part liquid nitrogen is crossed through subcooler and is seen distillation system off as liquid nitrogen product after cold, and the remainder liquid nitrogen is delivered in the evaporimeter after the liquid nitrogen pump pressurization, carries out heat exchange with air from above-mentioned main heat exchanger and is able to vaporization; Liquid nitrogen after the vaporization is delivered to above-mentioned main heat exchanger re-heat again to normal temperature, becomes product high pressure nitrogen gas and sees distillation system off.The high pure nitrogen that obtains at last rectifying column cat head, a part is taken out from last rectifying tower top, and is cold excessively through subcooler, again through above-mentioned main heat exchanger re-heat to normal temperature, press nitrogen product to see distillation system off in becoming.Another part high pure nitrogen is then in the 2# condenser/evaporator in the last rectifying column; With from last rectifier bottoms 1# condenser/evaporator and through the cold excessively oxygen-enriched liquid air of subcooler carry out heat exchange and condensation, condensed liquid nitrogen is participated in rectifying as phegma at last rectifying column, and the evaporation of the oxygen-enriched liquid air in the 2# of last rectifying column cat head condenser/evaporator, the gas after this evaporates is again after the subcooler heat exchange; Get into the 2# decompressor and carry out constant entropy expansion; Produce cold, this cold to normal temperature, is seen distillation system through above-mentioned main heat exchanger re-heat off; Remove next unit purification system regeneration purifier, realized the second level constant entropy expansion kind of refrigeration cycle of backflowing like this.
The present invention adopts technique scheme; Produce the nitrogen space division technique owing to carry out compressing in multistage rectifying, twin-stage constant entropy expansion kind of refrigeration cycle and the band evaporimeter, the high pure nitrogen product of different output pressures, the work of separation in the reasonable distribution distillation process are produced in the ability segmentation; Promptly reduce effectively and produce the irreversible loss in the high pure nitrogen process; Utilize the available useful work in the technological process fully, make it to be converted into and produce needed cold in the high pure nitrogen space division technique flow process, thereby can increase the output of liquid nitrogen product; Can also necessary condition be provided for the interior compression of nitrogen product; Compression adds the flow arrangement that has evaporimeter in the implementation part liquid nitrogen product, has not only solved defectives such as the equipment that the product external compression caused increases, investment increases, external pressure lectotype selection difficulty, product nitrogen gas pressurization back purity reduction; Improve the air compressor machine row pressure height that the processing air pressure is brought, shortcomings such as energy consumption increase, the increase of pressure of equipment grade, equipment cost increase but also reduced simple employing.If when obtaining following product high pressure nitrogen gas with prior art, the high pressure nitrogen discharge pressure is: 1.4MPa (A), output: 1000N 3/ h, purity: oxygen content is less than 5PPM, and then the air compressor machine row pressure will reach 1.49MPa (A), and the present invention is when adopting in the band evaporimeter compression method to reach above-mentioned same index, the air compressor machine row pressure then be 1.2MPa (A), the about 256KW of air compressor machine energy consumption reduction.The present invention compared with present technology, energy-saving effect is remarkable.The present invention can reduce system of unit nitrogen energy consumption effectively and improve the nitrogen recovery rate, and its system of unit nitrogen energy consumption is about 0.2164KW.h/Nm 3N 2, and the nitrogen recovery rate can reach 71%, and the high-purity nitrogen plant performance is greatly improved, and can significantly improve liquid nitrogen production, compared with present technology liquid nitrogen production can be more than 2 times of prior art.High pressure nitrogen and middle nitrogen product of pressing two or more pressure rating of nitrogen can also be provided simultaneously.And, compared with present technology only need increase by two liquid nitrogen pumps, two decompressors and evaporimeter, equipment investment and floor space increase less, and the equipment pressure rating also is minimized.Simultaneously simple to operate, liquid nitrogen, high pressure nitrogen and the middle equal scalable of output of pressing nitrogen, the variable working condition ability is strong.
Description of drawings
Accompanying drawing is produced high pure nitrogen space division technique process principle figure for multistage rectifying.
The specific embodiment
Describe the specific embodiment of the present invention in detail below in conjunction with accompanying drawing.
The present invention adopts multistage rectifying, twin-stage constant entropy expansion kind of refrigeration cycle and the interior compression process of band evaporimeter to produce high pure nitrogen.Existing is example with two sections rectifying, and its concrete technological process is following:
< 1>air gets into chilldown system 16 precoolings after 15 compressions of air filtration and compressibility, get into purification system 17 purifying again after; Get dry compressed air; Send into the main heat exchanger that is arranged in ice chest 51 of distillation system to this compressed air, carry out heat exchange, and compressed air self that should drying is able to cooling with the cold air of backflowing; When dried compressed air be cooled to＜15 ℃ the time; A part is taken out the 1# decompressor 2 that goes to be arranged in ice chest 5 and is carried out adiabatic expansion, and the part cold of generation gets into goes up rectifying column 8 participation rectifying, realizes first order drag flow constant entropy expansion kind of refrigeration cycle;
< 2>remaining compressed air continues to be cooled in above-mentioned main heat exchanger 1, and the further heat exchange of liquid nitrogen after being cooled to saturation temperature and delivering to the evaporimeter 4 that is arranged in ice chest 5 and pressurization is delivered to the following rectifying column 11 that is arranged in ice chest 5 and participated in rectifying after the heat exchange; Described saturation temperature is along with the variation of the required pressure of technological process changes, and existing is example with saturation temperature-110K, through the rectifying of rectifying column 11 down; Cat head at this time rectifying column 11 has produced high pure nitrogen; And at the bottom of tower, having produced oxygen-enriched liquid air, this oxygen-enriched liquid air takes out from descend rectifying column 11 after subcooler 14 mistakes are cold, delivers to the last rectifying column 8 that is arranged in ice chest 5 and participates in rectifying; Oxygen-enriched liquid air in high pure nitrogen that following rectifying column 11 cats head obtain and the last rectifying column 8 bottom 1# condenser/evaporators 9 carries out heat exchange; The evaporation of this oxygen-enriched liquid air becomes the rising steam of going up in the rectifying column 8, and high pure nitrogen is liquefied and is liquid nitrogen, and wherein a part of liquid nitrogen is back to down as phegma and participates in rectifying in the rectifying column 11; And another part liquid nitrogen through subcooler 14 cross cold after as liquid nitrogen product; See distillation system off after liquid nitrogen graduated cylinder 10 metering in ice chest 5, get into storage system 12, the remainder liquid nitrogen adds through liquid nitrogen pump 6 and is sent in the evaporimeter 4; With carry out from the air in the said main heat exchanger 1 heat exchange be able to the vaporization; Liquid nitrogen after the liquefaction is delivered in the main heat exchanger 1 re-heat again to normal temperature, product high pressure nitrogen gas, and see distillation system off to user 18.
And, getting into said going up in the rectifying column 8 after the participation rectifying from the expanded air of said 1# decompressor 2 and from the said oxygen-enriched liquid air of rectifying column 11 down, the cat head of rectifying column 8 obtains high pure nitrogen on this, and at the bottom of tower, obtains high oxygen-enriched liquid air.Part in this high oxygen-enriched liquid air is taken out from last rectifying column 8 bottoms, through subcooler 14 cross cold after, deliver in the 2# condenser/evaporator 7 at rectifying column 8 tops as low-temperature receiver.And go up the high pure nitrogen at rectifying column 8 tops, a part is taken out in this tower, through subcooler 14 cross cold after, get into main heat exchanger 1 re-heat to normal temperature, in press nitrogen product, see distillation system off to user 18.Another part high pure nitrogen is delivered in the said 2# condenser/evaporator 7; With carry out heat exchange and condensation from last rectifying column 8 bottom 1# condenser/evaporators 2 and through the cold excessively high oxygen-enriched liquid air of subcooler 14, return rectifying column 8 as phegma after the heat exchange condensation and participate in rectifying, and the high pure nitrogen heat exchange at the high oxygen-enriched liquid air in this 2# condenser/evaporator 7 and last rectifying column 8 tops and vaporize after; Send into subcooler 14 heat exchange; Then, get into the 2# decompressor 3 that is arranged in ice chest 5 and carry out adiabatic expansion, the high oxygen-enriched air after the expansion gets into after main heat exchanger 1 re-heat and sees distillation system off; Remove purification system 17 regeneration purifiers, constant entropy expansion kind of refrigeration cycle thereby backflow in the realization second level.When fluid discharge groove 13 stops for equipment, the usefulness of remaining liq discharging.

Claims (1)

1. the high pure nitrogen space division technique is produced in a multistage rectifying, it is characterized in that this technology comprises the steps:
< 1>will be through the dried compressed air behind compression, precooling, the purifying; Send in the main heat exchanger (1) in the distillation system and carry out heat exchange with the cool gas that backflows; This dried compressed air self is able to cooling; Cooled part compressed air is sent to 1# decompressor (2) and is carried out constant entropy expansion, and the part cold of generation gets into goes up rectifying column (8) participation rectifying, thereby realizes first order constant entropy expansion kind of refrigeration cycle;
< 2>the residue dried compressed air in the said main heat exchanger (1) is further cooled off, and in this main heat exchanger (1), is cooled to saturation temperature, deliver in the evaporimeter (4) with pressurization after the further heat exchange of liquid nitrogen after; Deliver to down rectifying column (11) again and participate in rectifying, in following rectifying column (11) distillation process, produce high pure nitrogen in the top of following rectifying column (11); This high pure nitrogen carries out heat exchange and forms liquid nitrogen with the oxygen-enriched liquid air of last rectifying column (8) bottom in 1# condenser/evaporator (9), and the liquid nitrogen after part is liquefied is participated in rectifying column (11) rectifying down as phegma, and another part liquid nitrogen is crossed through subcooler (14) and seen distillation system off as liquid nitrogen product after cold; The remainder liquid nitrogen is delivered in the evaporimeter (4) after liquid nitrogen pump (6) pressurization, is able to vaporization with carry out heat exchange from the air in the said main heat exchanger (1), and the liquid nitrogen after the vaporization is delivered to the middle re-heat of this main heat exchanger (1) again to normal temperature; Become product high pressure nitrogen gas and see distillation system off, and the high pure nitrogen that the cat head of last rectifying column (8) obtains, a part is taken out from last rectifying column (8) cat head; Cold excessively through subcooler (14); Again through said main heat exchanger (1) re-heat to normal temperature, press nitrogen product to see distillation system off in becoming, and in the 2# condenser/evaporator (7) of another part high pure nitrogen in the last rectifying column (8); With 1# condenser/evaporator (9) bottom last rectifying column (8) and through subcooler (14) cold excessively oxygen-enriched liquid air heat exchange and condensation; Condensed liquid nitrogen is participated in rectifying as phegma in last rectifying column (8), and the evaporation of the oxygen-enriched liquid air in the 2# condenser/evaporator (7) in last rectifying column (8), the gas after this evaporation is again after subcooler (14) heat exchange; Send into 2# decompressor (3) and carry out constant entropy expansion; Produce cold, this cold is seen distillation system through said main heat exchanger (1) re-heat off to normal temperature; Remove purification system (17) regeneration purifier, thereby realize second level constant entropy expansion kind of refrigeration cycle.
CN2011103019576A 2011-09-28 2011-09-28 Air-separation process for preparing high-purity nitrogen by multi-segment rectification Pending CN102506559A (en)

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