CN1088183C - 空气分离 - Google Patents

空气分离 Download PDF

Info

Publication number
CN1088183C
CN1088183C CN96104330A CN96104330A CN1088183C CN 1088183 C CN1088183 C CN 1088183C CN 96104330 A CN96104330 A CN 96104330A CN 96104330 A CN96104330 A CN 96104330A CN 1088183 C CN1088183 C CN 1088183C
Authority
CN
China
Prior art keywords
pressure
liquid
nitrogen
low
oxygen
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CN96104330A
Other languages
English (en)
Other versions
CN1135596A (zh
Inventor
T·拉思邦
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BOC Group Ltd
Original Assignee
BOC Group Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BOC Group Ltd filed Critical BOC Group Ltd
Publication of CN1135596A publication Critical patent/CN1135596A/zh
Application granted granted Critical
Publication of CN1088183C publication Critical patent/CN1088183C/zh
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

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
    • F25J3/04151—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
    • F25J3/042—Division of the main heat exchange line in consecutive sections having different functions having an intermediate feed connection
    • 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
    • F25J3/04212—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 and simultaneously condensing vapor from a column serving as reflux within the or another 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
    • F25J3/04406—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
    • F25J3/04418—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 with thermally overlapping high and low pressure columns
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/20—Processes or apparatus using separation by rectification in an elevated pressure multiple column system wherein the lowest pressure column is at a pressure well above the minimum pressure needed to overcome pressure drop to reject the products to atmosphere
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • 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
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/50—Oxygen or special cases, e.g. isotope-mixtures or low purity O2
    • 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
    • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
    • F25J2235/52—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being oxygen enriched compared to air ("crude 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
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream
    • 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
    • F25J2250/20—Boiler-condenser with multiple exchanger cores in parallel or with multiple re-boiling or condensing 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
    • 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
    • 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
    • F25J2250/52—One fluid being oxygen enriched compared to air, e.g. "crude oxygen"
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S62/00—Refrigeration
    • Y10S62/90—Triple column
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S62/00—Refrigeration
    • Y10S62/902—Apparatus

Landscapes

  • 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

经压缩的空气流在单元4中除去二氧化碳和水蒸气，空气流过热交换器6被冷却到适于精馏的温度。在高压精馏器12中空气被分离成富氧液体和氮蒸气。使富氧液流减压并将其送入装有再沸腾器22的相分离器42，结果进一步分离而形成更浓的液流和中间蒸气。在低压精馏器34中更浓的液流被分离成氧和氮。中间蒸气流在冷凝器46中被冷凝并被送入低压精馏器34中。通过与来自精馏器34的中间传质区的液体进行间接热交换使精馏器12中分离出的氮蒸气冷凝而形成精馏器12和34的部分液氮回流。通过与来自精馏器34的氮蒸气进行间接热交换在冷凝器-再沸腾器72中使精馏34的不纯氧产品蒸发而形成另一部分液氮回流。

Description

空气分离
本发明涉及一种空气分离方法和装置。
工业上最重要的空分方法是精馏。最常用的空分循环包括下述几步：压缩空气流；通过除去水蒸汽和二氧化碳纯化已压缩的空气流，以及通过与回流的产品流进行热交换将已压缩的空气流预冷到适于精馏的温度。在所谓“双精馏塔”中进行精馏，上述双精馏塔包括一个高压和一个低压精馏塔，也就是说，两个塔中的一个塔的工作压力高于另一塔，将大部分空气而并非全部空气导入高压塔并使之分离成富氧液空气和液氮蒸气。再将氮蒸气冷凝。将一部分冷凝物用作高压塔的回流液。从高压塔底部抽取富氧液体使之过冷，并经节流阀或减压阀将其送入低压塔的中部区域。在低压塔中，将富氧液体分离成大体为纯净的氧和氮产品。从低压塔以蒸气形式抽取上述产品。并将它们再作为回流液与流入的空气流进行热交换。从高压塔中抽取剩余冷凝物作为低压塔的回流液，使其过冷，再经过节流阀或减压阀将其送入低压塔的顶部。
通常，低压塔的工作压力范围为1-1.5巴。(除非指明意思相反，此处给出的全部压力为绝对压力，而不是标准压力。)将低压塔底部的液氧用在高压塔顶部起冷凝的作用。据此，使来自高压塔顶部的氮蒸气与低压塔底部的液氧进行热交换。因而可使液氧充分蒸发以满足低压塔再沸腾的需要，并提高气态氧产品的产率。使高压塔顶部的压力和经压缩的输入空气的压力值能满足冷凝氮的温度比低压塔中沸腾氧的温度高1-2K的要求。由于这些关系，通常，高压塔的工作压力不低于约5巴。
低压塔也可能在较高的压力下运行。如果低压精馏塔的工作压力升高，高压塔的工作压力亦随之升高。
为了产生不纯的氧产品，比方说，按体积计杂质的含量占3％-20％，曾有人建议，通过调整高压塔和低压塔之间的压力比来改进空分过程。在US-A-4410343中曾提出，如果需要纯度较低的氧，高低压塔之间不必保持上述关系。为了使低压塔再沸腾和蒸发氧产品，可以采用空气以使低压塔底部氧沸腾。然后将所形成的冷凝空气送入高压塔和低压塔中，从高压塔抽取富氧液流，使其流过节流阀，其中一部分用于冷凝高压塔顶部的氮。
US-A-3210951也公开了一种生产不纯氧的工艺流程，其中采用空气使低压塔底部的氧沸腾，以使低压塔再沸腾并蒸发氧产品。可是，在该例中，从低压塔的中部区域抽取富氧液流以完成冷凝高压塔中生产出的氮蒸气的功能。该工艺过程可将高压塔的工作压力降至4巴左右。
若低压塔的工作压力高于约1.5巴，US-A-3210951和US-A4410343所披露的方法就不太适用了。
EP-A-0538118公开了一种在通常的压力范围以上而不影响氧回收并能降低能源消耗的双塔工艺操作方法。在一个实例中，从高压精馏塔的底部抽取富氧液空，在高于另一塔的所有液体-蒸气转变表面之处将其引入该另一塔中。上述另一塔的工作压力为高压塔工作压力和低压塔工作压力的中间压力，从所述另一塔将液体和蒸气输入到低压塔的中部。
公布于1995年1月11日、公开号为EP-A-0633438的欧洲专利申请94302953.8结合其附图2公开了一种工艺流程，该流程除通过与从高压精馏塔中抽取的氮进行热交换蒸发不纯氧产品外，其它部分大体与本申请附图所示相似。这种流程的缺点是如果低压精馏器的工作压力比5巴高得多的话，产品的回收(也就是产氧率)就下降，在所谓的综合气化联合循环(IGCC)工艺中对高压氮产品的需求有所增加，因为氮气被送入通过燃料气体燃烧发电的气体涡轮机的燃烧室或膨胀机中，而上述燃料气体是一种气化产品。空气分离的氧产品本身还用作生产燃料气的反应物。因此，这种循环的优点是低压精馏器的工作压力范围为5-10巴时也不降低氧气产率。本发明旨在提供一种能具有这种优点的方法和装置。
根据本发明所提供的空分方法分括以下步骤：
a)使经预冷却和纯化的空气在高压精馏器中分离成富氧液体和氮蒸气；
b)在高压精馏器顶部压力和低压精馏器底部压力之间的压力下分离上述富氧液流，从而形成更浓的富氧液流和中间蒸气；
c)在低压精馏器中将更浓的液流分离成氧和氮；
d)向高压和低压精馏器提供液氮回流；
e)冷凝上述中间蒸气流，至少将所产生的冷凝物的一部分送入低压精馏器中；
其中，通过与来自低压精馏器中间传质区的液体进行间接热交换使上述氮蒸气冷凝，而形成液氮回流的一部分，通过与低压精馏器的蒸气氮产品进行间接热交换蒸发低压精馏器的不纯氧产品，形成上述液氮回流的另一部分。
本发明还提供了空分装置，该装置包括：
a)一台将预冷却和纯化后的空气分离成富氧液体和氮蒸气的高压精馏器：
b)一台生产氧和氮的低压精馏器：
c)在高压精馏器顶部压力和低压精馏器底部压力之间的压力下分离上述富氧液流以便生成更浓的富氧液体和中间蒸气的设备：
d)将更浓的富氧液流送入低压精馏器以便分离成氧和氮的设备：
e)一台冷凝上述中间蒸气流的第一冷凝器.该第一冷凝器有一个使所生成的冷凝物流入低压精馏器的出口：以及
f)向高、低压精馏器供给液氮回流的设备，该设备包括将氮蒸气流与来自低压精馏器的中间传质区的液体进行间接热交换的第二冷凝器以及通过与低压精馏器的冷凝的蒸气产品进行间接热交换蒸发低压精馏器的不纯的液体产品的第三冷凝器。
由于中间蒸气通常含氮量按体积计高于80％，可以采取将上述冷凝物的上述部分送入低压精馏器，以消除低压精馏器工作压力提高时低压精馏器中回流不足的倾向。如上面所提到的，这种回流不足的趋势在低压精馏器工作压力高于5巴时变得尤其明显。但是，根据本发明，低压精馏器的部分液氮回流液是通过从低压精馏器抽取氧产品使之在与低压精馏器的氮蒸气产品进行间接热交换的过程中蒸发而得到的，用于低压精馏器的液氮回流液可以比蒸发流体源高压精馏器顶部时的多。因为在后面的实例中，需要将所得到的氮冷凝物的一部分返送到高压精馏器中以用作高压精馏器的回流，因此，降低了用于低压精馏器的氮冷凝物的比例。
既可以通过(i)在另一精馏器中精馏(下面往往称之为“中间精馏”)，也可以通过(ii)在高压精馏器顶部压力和低压精馏器底部压力之间的压力下使富氧液流闪蒸以形成液体-蒸气混合物再将所形成的液体-蒸气混合物分离成液相和蒸气相以便形成更浓的液体和中间蒸气(这些步骤总起来称之为“中间闪蒸分离”)来实现本发明方法的步骤(b)中富氧液流的分离。为了提高中间蒸气的形成速率，最好使一部分更浓的液体再沸腾。
如果采取中间精馏实现本发明方法的步骤(b)，最好在该另一精馏器的所有液体-蒸气变换装置的下方输入富氧液流。最好使上述液体与来自高压精馏器的另一股氮蒸气进行间接热交换使部分上述液体再沸腾，同时使氮冷凝。(此种氮冷凝提供另一回流源，此回流源最好用于高压精馏器中。)为此，上述另一精馏器最好装有一个再蒸发器，以便使此精馏器底部的液体部分地再沸腾。上述另一精馏器最好生产作为中间蒸气的氮气。
如果采用中间闪蒸分离来完成本发明方法的步骤(b)，可以在相分离器的上游或相分离器中实现部分再沸腾。通过与来自高压精馏器的另外的氮蒸气流进行间接热交换可实现上述部分再沸腾，同时使氮冷凝。上述氮冷凝物可作为高压精馏器和/或低压精馏器的另一回流源。
不管用什么方式完成步骤(b)，最好通过与更浓的液流进行间接热交换完成中间蒸气的冷凝，上述更浓的液流在间接热交换之前压力被降低。借此常使上述更浓液流部分蒸发，同时最好将所得到的流体输入低压精馏器。(如果需要，可将更浓液流送入低压精馏器，使之与中间蒸气进行间接热交换。)此外，也可通过与从低压精馏器的中间传质区抽取的液体进行间接热交换使中间蒸气冷凝，从而使从低压精馏器的中间传质区抽出的液体至少部分再沸腾。最好使再沸腾的液体再返回到低压精馏器的传质区。
通常，通过在再沸腾器-冷凝器中与经预冷和纯化的原料空气进行间接热交换可使低压精馏器底部再沸腾，从而使原料空气流至少部分冷凝。
最好高压精馏器和上述另一精馏器各包括一个精馏塔。低压精馏器也可以包括一个独立的精馏塔，或者可以包括两个分离的塔。后一种安排的优点是可以将使氮蒸气流与来自低压精馏器中间传质区的液体进行间接热交换的第二冷凝器置于一个塔的底部区，因此，第二冷凝器可以是一种传统的温差环流型冷凝器-再沸腾器。
最好使低压精馏器中分离出的氧的纯度达85％-96％。最好使低压精馏器中分离出的氮纯度至少为98％。
通过或使原料空气流或使氮流对外作功膨胀的性能可以使本发明方法进行制冷。
下面结合附图用举例的方式对本发明的方法和装置进行描述，所示附图为本发明的空气分离装置的流程示意图，该附图没有按比例绘制。
参见附图，原料空气流由压缩机2压缩，然后使被压缩的原料空气流经过纯化单元4，有效地除去空气流中的水蒸汽和二氧化碳。压缩机2通常构成气体透平(未示出)的一部分，在气体透平中，例如原料空气流只是压缩机2输出的一小部分，该部分原料空气流在位于纯化单元4上游的单独的热交换器(未示出)中被冷却到约为环境温度。
为了有效地除去水蒸气、二氧化碳及如碳氢化合物之类的其它杂质，纯化单元4采用若干吸附剂床(未示出)。上述若干床彼此不连续运行，因此，当一个或几个床对原料空气流进行纯化时，其余的床处于再生阶段，例如用热氮流进行吹洗。这类纯化单元及其运行情况均是公知的，此处无需进一步描述。
将纯化后的原料空气流分第一和第二空气流。使第一空气流流过主热交换器6，从其热端8流到其冷端10，从而使第一空气流从约为环境温度冷却到其饱和温度(或者适于用精馏对其进行分离的其他温度)。使被冷却的第一空气流流过冷凝器-再沸腾器16的冷凝通道而部分冷凝，将所得到的部分冷凝空气经入口18送入高压精馏塔12。高压精馏塔12包括液体-蒸气接触设备(未示出)，借助该设备使下行的液相与上升的蒸气相直接接触，因而在两相之间出现传质。
上述下行的液相逐渐地富含氧，而上升的蒸气相逐渐地富含氮。上述液体-蒸气接触设备可以包括液体-蒸气接触盘构件和相关的下行管。或者可以包括网格填料或不规则填料。通常将富氧液空气(未示出)收集在高压精馏塔12的底部。
为使从液体-蒸气接触设备的顶部流出的蒸气馏分基本上是纯氮，上述液体-蒸气接触设备(未示出)应具有足够的塔盘数或足够高度的填料，通过出口20从高压精馏塔12的顶部抽出的氮蒸气流在另一个再沸腾器-冷凝器22中被冷凝。冷凝物再通过入口24返回到处于高压精馏塔12的顶部的收集器30中。使从高压精馏塔12顶部抽出的另一股氮蒸气流在又一个冷凝器-再沸腾器28中冷凝。再将冷凝器-再沸腾器28流出的冷凝物返回到收集器30中。将流入收集器30的液氮的一部分用作高压精馏塔12的液氮回流；如下面将要描述的那样，将冷凝物的另一部分用作低压精馏器(即精馏塔)34的回流液。
使通过出口36从高压精馏塔12底部抽取的富氧液流(通常以氧体积含量计含氧30-35％)在热交换器38中过冷。使过冷的富氧液流经第一减压阀40闪蒸，形成含氧贫乏的闪蒸气(“中间蒸气”)和含氧更浓的剩余液体的混合物。通过入口44将上述含氧更浓的液体和中间蒸气的混合物送入相分离器42的底部区域。相分离器42装有冷凝器-再沸腾器22。该冷凝器-再沸腾器适用于沸腾部分液相。这种再沸腾过程提高了中间蒸气形成的速率。另一个冷凝器-再沸腾器46将从相分离器42的顶部抽出的蒸气冷凝。将所形成的冷凝物的一部分经节流阀35送入低压精馏器34，以用作在其中分离的第一股流体。将所得到的冷凝物的另一部分由泵43返送到高压精馏塔12的中部传质区。
通过出口48从  相分离器42的底部连续地抽取剩余的更浓的液流(通常，按体积计约含氧40％)使其中的一部分通过节流阀或减压阀49，致使其压力降至约为低压精馏器34的工作压力。所形成的降压后的更浓液体(通常含部分蒸气)流过冷凝器-再沸腾器46，从而冷却该冷凝器-再沸腾器中的氮蒸气冷凝物。使上述更浓液流在冷凝器-再沸腾器46中至少部分蒸发，将所形成的富氧流作为第二原料流在中部经入口50送入低压精馏器34中。剩余更浓的液氧经节流阀51减压，并作为第三原料流通过位于入口50上方的入口53被送入低压精馏器34。
借助于来自纯化单元4的第二股已纯化的空气流来满足附图中所示装置的制冷要求。并使该股空气流经压缩机80进一步压缩，通过使压缩后的第二股空气流与第一空气流同向流动将第二空气流冷却到介于热交换器6的冷端10和热端8的温度之间的中间温度。从主热交换器6的中部区域抽取第二空气流，并使其在透平膨胀机82中对外作功膨胀。再使所得到的膨胀后的气流返回到热交换器6中。使之流过该热交换器后温度进一步降低。膨胀后的第二空气流流出热交换器6的冷端10后经入口84流入低压精馏器34，此股气流作为第四原料流与其它三股原料流一道被分离。
四股原料流在低压精馏器34中分离生成氧产品和氮产品低压精馏器34包含液体-蒸汽接触设备(未示出)，在该设备中下行的液相与上行的蒸气相直接接触，因此在两相之间发生传质。此液体-蒸气接触设备(未示出)可以与高压精馏塔12中所用的液体-蒸气接触设备相同，也可以与其不同。可从两处向低压精馏器34供应液氮回流。第一处为收集器30的出口66，从收集器30抽取液氮流，使之在热交换器38中过冷，已过冷的液氮流经减压阀68再经入口70流入低压精馏器34的上部区域。从低压精馏器34的顶部抽取氮蒸气流。使其在冷凝器-再沸腾器72中冷凝，将所形成的氮冷凝物返回到精馏器34的顶部。这就构成了第二股液氮回流，故而形成了向下流过低压精馏器34的液体。借助于使该精馏器底部液体再沸腾的冷凝器-再沸腾器16的运行可形成朝上流过低压精馏器34的蒸气。通过使该精馏器34中部流体再沸腾的冷凝器-再沸腾器22的运行可以增加流过低压精馏器34上部区域的蒸气流。
通过出口76从低压精馏器34底部区域抽取氧产品，通常其纯度达90％-95％。再使此氧产品流过热交换器38而过冷，然后使上述氧产品流过节流阀77并在冷凝器-再沸腾器72中蒸发，使所形成的氧蒸气先流过热交换器38，再从主热交换器6的冷端10流到其热端8而复热。可以使所得到的约为环境温度的氧产品经压缩机84压缩到适于气化反应的压力。从低压精馏器34的顶部抽取气氮产品流，使其流过热交换器38，从而可为其它流过该热交换器的流体过冷提供冷量。从热交换器38流出的氮气流入热交换器6，从其冷端10流到热端8，此股氮气流离开热交换器6时接近环境温度。还可以使氮气流经压缩机86压缩到压力范围为15至20巴，然后送入气体涡轮机的燃烧室(未示出)。
此外，可从高压精馏塔12顶部抽取高压气氮产品，并使其流入主热交换器6从该热交换器的冷端10流到热端8而复热。还可使该氮产品经压缩机88压缩。附图所示装置最显著的优点是：即使精馏器34工作在6巴压力而且从高压精馏塔12抽取高达20％的氮产品也能向低压精馏器34供给足够的回流。
在附图所示装置运行的典型实例中，高压塔12的工作压力约13.5巴，低压精馏器34的压力约6巴，相分离器42的工作压力约为9巴，冷凝器-再沸腾器72的压力约1.8巴。

Claims (13)

1.一种空气分离方法，包括下述步骤：
(a)在高压精馏器中将经预冷却和纯化的空气分离成富氧液体和氮蒸气：
(b)在高压精馏器顶部压力和低压精馏器底部压力之间的压力下分离上述富氧液流，从而形成更浓的富氧液流和中间蒸气；
(c)在低压精馏器中将上述更浓的液体分离成氧和氮；
(d)向高压和低压精馏器提供液氮回流；
(e)冷凝上述中间蒸气流，至少将所产生的冷凝物的一部分送入低压精馏器；
其中，通过与来自低压精馏器中间传质区的液体进行间接热交换，使上述氮蒸气冷凝而形成液氮回流的一部分；通过与低压精馏器的蒸气氮产品进行间接热交换蒸发低压精馏器的不纯氧产品形成上述液氮回流的另一部分。
2.如权利要求1所述的方法，其中通过在另一精馏器中精馏来实现步骤(b)中的富氧液流的分离。
3.如权利要求1或2所述的方法，其中上述中间蒸气是氮。
4.如权利要求1所述的方法，其中，在高压精馏器顶部压力和低压精馏器底部压力之间的压力下使富氧液流闪蒸发形成液体-蒸气混合物；再将所形成的液体-蒸气混合物分离成液相和蒸气相以便形成更浓的液体和中间蒸气，借此完成步骤(b)中富氧液流分离。
5.如权利要求4所述的方法，其中使上述更浓的液体的一部分再沸腾。
6.如权利要求5所述的方法，其中，通过与来自高压精馏器的另一股氮蒸气流进行间接热交换完成上述部分再沸腾，同时使氮冷凝。
7.如上述任一项权利要求所述的方法，其中通过与上述更浓液流进行间接热交换实现中间蒸气的冷凝，上述更浓液流在进行间接热交换之前被减压。
8.如上述任一项权利要求所述的方法，其中通过在再沸腾器-冷凝器中与冷凝的预冷和纯化后的原料空气进行间接热交换而使低压精馏器底部再沸腾。
9.空分装置，包括：
a)一台将预冷和纯化后的空气分离成富氧液体和氮蒸气的高压精馏器；
b)一台生产氧和氮的低压精馏器；
c)在高压精馏器顶部压力和低压精馏器底部压力之间的压力下分离上述富氧液流以便形成更浓的富氧液体和中间蒸气的设备；
d)将更浓的液流送入低压精馏器以便分离出氧和氮的设备；
e)一台冷凝上述中间蒸气流的第一冷凝器，该第一冷凝器有一个使所生成的冷凝物流入低压精馏器的出口；以及
f)向高、低压精馏器提供液氮回流的设备，该设备包括将氮蒸气流与来自低压精馏器中间传质区的液体进行间接热交换的第二冷凝器，以及通过与低压精馏器的顶部蒸气产品进行间接热交换蒸发低压精馏器的不纯液体产品的第三冷凝器。
10.如权利要求9所述的装置，其中，上述分离设备包括另一台精馏器。
11.如权利要求9所述的装置，其中，上述分离设备包括一个减压阀和一个位于该减压阀下游的相分离器。
12.如权利要求11所述装置，还包括一台位于相分离器上游或位于相分离器中的再沸腾器。
13.如权利要求9至12中任一项所述的装置，还包括一台和低压精馏器底部相通的再沸腾器-冷凝器，该再沸腾器-冷凝器包括与预冷、纯化后的空气源相通的冷凝通道。
CN96104330A 1995-01-05 1996-01-05 空气分离 Expired - Fee Related CN1088183C (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9500120.2A GB9500120D0 (en) 1995-01-05 1995-01-05 Air separation
GB9500120.2 1995-01-05

Publications (2)

Publication Number Publication Date
CN1135596A CN1135596A (zh) 1996-11-13
CN1088183C true CN1088183C (zh) 2002-07-24

Family

ID=10767614

Family Applications (1)

Application Number Title Priority Date Filing Date
CN96104330A Expired - Fee Related CN1088183C (zh) 1995-01-05 1996-01-05 空气分离

Country Status (8)

Country Link
US (1) US5644933A (zh)
EP (1) EP0721094B1 (zh)
JP (1) JPH08240380A (zh)
CN (1) CN1088183C (zh)
AU (1) AU706680B2 (zh)
DE (1) DE69521285T2 (zh)
GB (1) GB9500120D0 (zh)
ZA (1) ZA9633B (zh)

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5761927A (en) * 1997-04-29 1998-06-09 Air Products And Chemicals, Inc. Process to produce nitrogen using a double column and three reboiler/condensers
US5881570A (en) * 1998-04-06 1999-03-16 Praxair Technology, Inc. Cryogenic rectification apparatus for producing high purity oxygen or low purity oxygen
US6925821B2 (en) * 2003-12-02 2005-08-09 Carrier Corporation Method for extracting carbon dioxide for use as a refrigerant in a vapor compression system
US7533540B2 (en) * 2006-03-10 2009-05-19 Praxair Technology, Inc. Cryogenic air separation system for enhanced liquid production
US8286446B2 (en) * 2008-05-07 2012-10-16 Praxair Technology, Inc. Method and apparatus for separating air
JP5032407B2 (ja) * 2008-07-24 2012-09-26 大陽日酸株式会社 窒素製造方法及び装置
US20100124410A1 (en) * 2008-11-18 2010-05-20 Fsi International, Inc. System for supplying water vapor in semiconductor wafer treatment
WO2010132142A1 (en) * 2009-05-14 2010-11-18 Exxonmobil Upstream Research Company Nitrogen rejection methods and systems
US20130000352A1 (en) * 2011-06-30 2013-01-03 General Electric Company Air separation unit and systems incorporating the same
JP5355657B2 (ja) * 2011-10-21 2013-11-27 中国電力株式会社 発電システム
US9150801B2 (en) 2012-01-27 2015-10-06 General Electric Company System and method for heating a gasifier
US9145524B2 (en) 2012-01-27 2015-09-29 General Electric Company System and method for heating a gasifier

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3210951A (en) 1960-08-25 1965-10-12 Air Prod & Chem Method for low temperature separation of gaseous mixtures
GB2057660B (en) * 1979-05-17 1983-03-16 Union Carbide Corp Process and apparatus for producing low purity oxygen
US4410343A (en) 1981-12-24 1983-10-18 Union Carbide Corporation Air boiling process to produce low purity oxygen
US4453957A (en) * 1982-12-02 1984-06-12 Union Carbide Corporation Double column multiple condenser-reboiler high pressure nitrogen process
US4543115A (en) * 1984-02-21 1985-09-24 Air Products And Chemicals, Inc. Dual feed air pressure nitrogen generator cycle
US4936099A (en) * 1989-05-19 1990-06-26 Air Products And Chemicals, Inc. Air separation process for the production of oxygen-rich and nitrogen-rich products
US5006137A (en) * 1990-03-09 1991-04-09 Air Products And Chemicals, Inc. Nitrogen generator with dual reboiler/condensers in the low pressure distillation column
US5137559A (en) * 1990-08-06 1992-08-11 Air Products And Chemicals, Inc. Production of nitrogen free of light impurities
US5069699A (en) * 1990-09-20 1991-12-03 Air Products And Chemicals, Inc. Triple distillation column nitrogen generator with plural reboiler/condensers
US5231837A (en) 1991-10-15 1993-08-03 Liquid Air Engineering Corporation Cryogenic distillation process for the production of oxygen and nitrogen
US5257504A (en) * 1992-02-18 1993-11-02 Air Products And Chemicals, Inc. Multiple reboiler, double column, elevated pressure air separation cycles and their integration with gas turbines
GB9212224D0 (en) * 1992-06-09 1992-07-22 Boc Group Plc Air separation
GB9304710D0 (en) * 1993-03-08 1993-04-28 Boc Group Plc Air separation
GB9405071D0 (en) 1993-07-05 1994-04-27 Boc Group Plc Air separation
US5341646A (en) * 1993-07-15 1994-08-30 Air Products And Chemicals, Inc. Triple column distillation system for oxygen and pressurized nitrogen production

Also Published As

Publication number Publication date
EP0721094A2 (en) 1996-07-10
AU4072695A (en) 1996-07-11
ZA9633B (en) 1996-07-10
EP0721094B1 (en) 2001-06-13
US5644933A (en) 1997-07-08
AU706680B2 (en) 1999-06-24
JPH08240380A (ja) 1996-09-17
CN1135596A (zh) 1996-11-13
DE69521285D1 (de) 2001-07-19
EP0721094A3 (en) 1997-05-07
GB9500120D0 (en) 1995-03-01
DE69521285T2 (de) 2002-05-16

Similar Documents

Publication Publication Date Title
EP0633438B1 (en) Air separation
US5546766A (en) Air separation
CN1091867C (zh) 空气分离
CN1057380C (zh) 低温空气分离方法和设备
EP0577349B1 (en) Air separation
US5080703A (en) Air separation
CN1058468A (zh) 具有双进气侧冷凝器的低温空气分离系统
CN1088183C (zh) 空气分离
CN1123399A (zh) 空气分离
US5582031A (en) Air separation
JPH07198249A (ja) 空気を分離するための方法および装置
US5660059A (en) Air separation
TW554160B (en) Nitrogen generation
KR970004729B1 (ko) 극저온 공기 분리방법 및 장치
JPH11325717A (ja) 空気の分離
CN1084870C (zh) 分离空气的方法和设备
CN1277347A (zh) 空气的分离
CN1488908A (zh) 排除氮气的方法和设备
CN111542723B (zh) 一种基于深冷精馏工艺生产空气产品的方法及空分系统
US5689975A (en) Air separation
EP0722074A2 (en) Air separation
JPH06207776A (ja) 窒素と酸素を製造する方法及び設備
AU719240B2 (en) Air separation

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C10 Entry into substantive examination
SE01 Entry into force of request for substantive examination
C14 Grant of patent or utility model
GR01 Patent grant
C19 Lapse of patent right due to non-payment of the annual fee
CF01 Termination of patent right due to non-payment of annual fee