CN114838560A - Air separation device for preparing low-pressure oxygen and operation method - Google Patents

Air separation device for preparing low-pressure oxygen and operation method Download PDF

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Publication number
CN114838560A
CN114838560A CN202210435203.8A CN202210435203A CN114838560A CN 114838560 A CN114838560 A CN 114838560A CN 202210435203 A CN202210435203 A CN 202210435203A CN 114838560 A CN114838560 A CN 114838560A
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China
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air
heat exchanger
rectifying tower
expander
air separation
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CN202210435203.8A
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Chinese (zh)
Inventor
莫方淑
任文
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Sichuan Air Separation Plant Group Co ltd
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Sichuan Air Separation Plant Group Co ltd
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Priority to CN202210435203.8A priority Critical patent/CN114838560A/en
Publication of CN114838560A publication Critical patent/CN114838560A/en
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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
    • F25J3/04006—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
    • F25J3/04248—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
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    • 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
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    • 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
    • F25J3/04103—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 using solely hydrostatic liquid head
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    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04109—Arrangements of compressors and /or their drivers
    • F25J3/04115—Arrangements of compressors and /or their drivers characterised by the type of prime driver, e.g. hot gas expander
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    • 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
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    • 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
    • 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
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    • 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
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    • 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
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    • F25J3/04187—Cooling of the purified feed air by recuperative heat-exchange; Heat-exchange with product streams
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    • 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
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    • 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
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    • F25J3/04393—Details relating to the work expansion, e.g. process parameter etc. using multiple or multistage gas work expansion
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    • 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
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    • 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
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    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
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    • F25J2205/60—Processes or apparatus using other separation and/or other processing means using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
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    • 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)
  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

The invention provides an air separation device for preparing low-pressure oxygen and an operation method thereof, comprising two coupled air separation systems: the first air separation system comprises a first air compressor, a first expansion machine, a first heat exchanger, a first rectifying tower, a second rectifying tower and a first liquid oxygen evaporator; the second air separation system comprises a second air compressor, a second expansion machine, a second heat exchanger, a third rectifying tower, a fourth rectifying tower and a second liquid oxygen evaporator; the first coupling channel is connected with the second air compressor, the first heat exchanger and the first rectifying tower; the second coupling channel is connected with the first air compressor, the second heat exchanger and the second liquid oxygen evaporator; the exhaust pressure of the first air compressor is higher than that of the second air compressor. The device is coupled through two sets of air separation systems, and the first air compressor provides pressure air for the liquid oxygen evaporators of the two sets of air separation systems, and the second air compressor provides low-pressure air required by rectification for the two sets of air separation systems, so that the operation energy consumption is reduced, and the economic benefit is improved.

Description

Air separation device for preparing low-pressure oxygen and operation method
Technical Field
The invention relates to the technical field of low-temperature gas separation, in particular to an air separation device for preparing low-pressure oxygen and an operation method thereof.
Background
In the traditional air separation flow for preparing low-pressure oxygen by adopting a cryogenic process, when the required oxygen pressure is lower, the oxygen compressor with higher cost and relatively lower safety is replaced by a common liquid oxygen self-pressurization re-vaporization reheating process, in order to efficiently vaporize and utilize the self-pressurized liquid oxygen, the air is required to reach certain pressure, and the conventional configuration is as follows: when the oxygen production amount is large, an air supercharger is separately configured; when the oxygen production amount is small, if the superchargers are separately configured, firstly, the investment of the superchargers is large, and secondly, the superchargers with small flow are not suitable for model selection and have low efficiency, so that the pressure of the raw material air compressor is directly increased to realize the high-efficiency vaporization of the low-pressure liquid oxygen.
The direct configuration of a raw material air compressor with higher pressure replaces a supercharger, so that although the investment is more economic and the device is simplified, the energy consumption of the device is increased, and the operating cost is increased. The production cost of the product is not controlled by enterprises, and the market competitiveness of the product is improved.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides an air separation device for preparing low-pressure oxygen and an operation method thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
an air separation plant for producing low pressure oxygen, comprising a first air separation system and a second air separation system:
the first air separation system comprises a first air compressor, a first expander, a first heat exchanger, a first rectifying tower, a second rectifying tower, a first liquid oxygen evaporator, a first air pipeline and a second air pipeline;
the first air pipeline and the second air pipeline are both connected with the outlet end of the first air compressor, the first air pipeline is connected to the first liquid oxygen evaporator after passing through the first heat exchanger, and the second air pipeline is connected to the second rectifying tower after passing through the first expander and the first heat exchanger;
the second air separation system comprises a second air compressor, a second expander, a second heat exchanger, a third rectifying tower, a fourth rectifying tower, a second liquid oxygen evaporator, a fourth air pipeline and a fifth air pipeline;
the fourth air pipeline and the fifth air pipeline are both connected with the outlet end of the second air compressor; the fourth air pipeline is connected to the third rectifying tower through the second heat exchanger; the fifth air pipeline is connected to the fourth rectifying tower after passing through the second expander and the second heat exchanger;
the first space division system and the second space division system are connected through a first coupling channel and a second coupling channel;
the inlet end of the first coupling channel is connected with the second air compressor and is connected to the first rectifying tower through the first heat exchanger; the inlet end of the second coupling channel is connected with the first air compressor and is connected to the second liquid oxygen evaporator through the second heat exchanger;
the exhaust pressure of the first air compressor is higher than that of the second air compressor.
In an embodiment of the present application, the first air separation system further includes a third air pipeline, and the third air pipeline is sequentially connected to the first air compressor, the first heat exchanger, and the first rectifying tower;
and/or the presence of a gas in the gas,
the second air separation system further comprises a third expander, a sixth air conduit, and a seventh air conduit;
the sixth air pipeline is sequentially connected with the second air compressor, the compression end of the third expansion machine, the second heat exchanger and the second liquid oxygen evaporator;
and the seventh air pipeline is sequentially connected with the second air compressor, the second heat exchanger, the expansion end of the third expander, the second heat exchanger and the fourth rectifying tower.
In an embodiment of the present application, the third air pipe, the fifth air pipe, the sixth air pipe, the seventh air pipe, the first coupling channel, and the second coupling channel are all provided with a shut-off valve.
In one embodiment of the present application, the first coupling passage and the third air duct, the second coupling passage and the sixth air duct, and the fifth air duct and the seventh air duct may partially merge into a common duct.
In an embodiment of the application, the exhaust pressure of the first air compressor is 700-720 kPa, and the exhaust pressure of the second air compressor is 560-620 kPa.
In one embodiment of the present application, the process roles of the second expander and the third expander are different and not operated simultaneously.
In an embodiment of the present application, the first air separation system further includes a first condensation evaporator, the first rectifying tower, the first condensation evaporator and the second rectifying tower are sequentially arranged from bottom to top, and an evaporation side liquid outlet of the first condensation evaporator is connected with an evaporation side of the first liquid oxygen evaporator;
the second air separation system further comprises a second condensation evaporator, the third rectifying tower, the second condensation evaporator and the fourth rectifying tower are sequentially arranged from bottom to top, and an evaporation side liquid outlet of the second condensation evaporator is connected with an evaporation side of the second liquid oxygen evaporator.
An operation method of an air separation plant for producing low-pressure oxygen, the air separation plant being the air separation plant described above, the operation method comprising a first operation mode, the first operation mode comprising the steps of:
step S100: opening a first coupling channel and a second coupling channel;
step S200: the first air separation system operates, and raw material air is compressed by a first air compressor to obtain compressed air A;
step S210: a first part of the compressed air A enters a second coupling channel, is cooled by a second heat exchanger and then is sent to a condensation side of a second liquid oxygen evaporator;
step S220: a second part of the compressed air A enters a first air pipeline, is cooled by a first heat exchanger and then is sent to a condensation side of a first liquid oxygen evaporator;
step S230: the third part of the compressed air A enters a second air pipeline, sequentially passes through the compression end of the first expander, the first heat exchanger, the expansion end of the first expander and the first heat exchanger, and then is sent to a second rectifying tower to participate in rectification;
step S300: the second air separation system operates, and raw air is compressed by a second air compressor to obtain compressed air B;
step S310: a first part of the compressed air B enters a first coupling channel, is cooled by a first heat exchanger and then is sent to a first rectifying tower to participate in rectification;
step S320: a second part of the compressed air B enters a fourth air pipeline, is cooled by a second heat exchanger and then is sent to a third rectifying tower to participate in rectification;
step S330: and the third part of the compressed air B enters a fifth air pipeline, sequentially enters the compression end of the second expander, the second heat exchanger, the expansion end of the second expander and the second heat exchanger, and then is sent to a fourth rectifying tower to participate in rectification.
In an embodiment of the application, the air separation plant is the air separation plant described above, and the operation method further includes a second operation mode, where the second operation mode includes the following steps:
step M100: closing the first coupling channel and the second coupling channel;
step M200: the first air separation system operates, and raw air is compressed by a first air compressor to obtain compressed air C;
step M210: a first part of the compressed air C enters a third air pipeline, is cooled by a first heat exchanger and then is sent to a first rectifying tower to participate in rectification;
step M220: a second part of the compressed air C enters a first air pipeline, is cooled by a first heat exchanger and then is sent to a condensation side of a first liquid oxygen evaporator;
step M230: the third part of the compressed air C enters a second air pipeline, is sequentially processed by a compression end of a first expander, a first heat exchanger, an expansion end of the first expander and the first heat exchanger, and then is sent to a second rectifying tower to participate in rectification;
and/or the presence of a gas in the gas,
step M300: the second air separation system operates, and raw air is compressed by a second air compressor to obtain compressed air D;
step M310: a first part of the compressed air D enters a fourth air pipeline, is cooled by a second heat exchanger and then is sent to a third rectifying tower to participate in rectification;
step M320: a second part of the compressed air D enters a sixth air pipeline, is sequentially pressurized by a compression end of a third expander and cooled by a second heat exchanger, and then is sent to a condensation side of a second liquid oxygen evaporator;
step M330: and the third part of the compressed air D enters a seventh air pipeline, sequentially passes through the second heat exchanger, the expansion end of the third expansion machine and the second heat exchanger, and then is sent to a fourth rectifying tower to participate in rectification.
In one embodiment of the present application, when the first mode of operation is in operation, the third air duct, the sixth air duct, the seventh air duct, and the third expander are all in a closed state.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the air separation device for preparing low-pressure oxygen, the first air separation system and the second air separation system are arranged for coupling, and the first air compressor with higher matched pressure provides pressure air for the liquid oxygen evaporators of the two sets of air separation systems to exchange heat with the low-pressure liquid oxygen; a second air compressor with lower matched pressure provides low-pressure air required by rectification for the two sets of air separation systems; in the two sets of air separation systems, the operation requirements of the two sets of air separation systems can be met only by configuring the first air compressor with higher pressure, and compared with the traditional process, the configuration of the second air compressor in the second set of air separation systems can be reduced, so that the purposes of reducing operation energy consumption and improving economic benefits are achieved.
2. The first air separation system is provided with a third air pipeline, and the second air separation system is provided with a third expansion machine, a sixth air pipeline and a seventh air pipeline, so that the two sets of air separation systems can be operated in a coupling mode and can also be operated independently; and the energy consumption of the second air separation system during independent operation is slightly lower than that of the scheme with higher matching pressure of the traditional air compressor.
3. The air separation device provides an upgrading and transforming scheme for preparing low-pressure oxygen, when an original air separation system (a first air separation system in the application) is matched with an air compressor with higher pressure and a set of air separation system needs to be newly built, a second air separation system in the application can be used as the newly built air separation system, and the two sets of air separation systems are coupled through a first coupling channel and a second coupling channel; the air compressor of the second air separation system is configured with an air compressor with the exhaust pressure lower than that of the first air separation system, and the coupling operation can effectively ensure that the two sets of air separation systems normally operate to prepare the required low-pressure oxygen and can effectively reduce the overall operation energy consumption; in addition, two sets of air separation systems can independently operate, are convenient to overhaul and maintain and have strong adaptability.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic process flow diagram of an air separation plant in an embodiment of the present invention.
FIG. 2 is a schematic process flow diagram of an air separation plant in the second embodiment of the present invention.
Reference numerals:
100. a first air separation system;
110. a first air compressor; 111. a first air duct; 112. a second air duct; 113. a third air duct; 120. a first expander; 130. a first heat exchanger; 140. a first rectification column; 150. a second rectification column; 160. a first liquid oxygen evaporator; 170. a first condensing evaporator;
200. a second air separation system;
210. a second air compressor; 211. a fourth air duct; 212. a fifth air duct; 213. a sixth air duct; 214. a seventh air duct; 220. a second expander; 230. a third expander; 240. a second heat exchanger; 250. a third rectifying column; 260. a fourth rectifying column; 270. a second liquid oxygen evaporator; 280. a second condenser-evaporator;
300. a first coupling channel;
400. a second coupling channel;
500. and (6) cutting off the valve.
Detailed Description
In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the claimed embodiments. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Example one
As shown in fig. 1, an embodiment of the present invention provides an air separation plant for producing low-pressure oxygen, which comprises a first air separation system 100 and a second air separation system 200 coupled and connected with each other.
The first air separation system 100 includes a first air compressor 110, a first expander 120, a first heat exchanger 130, a first rectifying tower 140, a second rectifying tower 150, a first liquid oxygen evaporator 160, a first condensing evaporator 170, and the like.
The outlet end of the first air compressor 110 is connected to an air duct, which is divided into a first air duct 111 and a second air duct 112. The first air duct 111 is connected to the condensing side of the first liquid oxygen evaporator 160 after passing through the first heat exchanger 130. Namely, a part of the compressed air of the first air compressor 110 is cooled by the first heat exchanger 130 in the first air pipeline 111, and then sent to the condensation side of the first liquid oxygen evaporator 160 after being cooled to a certain temperature, and sent to the first rectifying tower 130 for rectification after being condensed by the liquid oxygen in the first liquid oxygen evaporator 160. The second air duct 112 is connected to the second rectification column 150 after passing through the first expander 120 and the first heat exchanger 130. Specifically, the other part of the compressed air of the first air compressor 110 enters the supercharging end of the first expander 120 through the second air pipeline 112 for supercharging, is cooled by the first heat exchanger 130 after supercharging, is sent to the expansion end of the first expander 120 for expansion and refrigeration after being cooled to a certain temperature, is returned to the first heat exchanger 130 for cooling again, and is sent to the second rectifying tower 150 for rectification after being cooled again.
The first rectifying tower 140, the first condensing evaporator 170 and the second rectifying tower 150 are sequentially arranged from bottom to top, and an evaporation side liquid outlet at the lower part of the first condensing evaporator 170 is connected with an evaporation side inlet of the first liquid oxygen evaporator 160 through a pipeline. The liquid oxygen obtained from the bottom of the second rectifying tower 150 enters the first condensing evaporator 170, and a part of the liquid oxygen is pumped out from the first condensing evaporator 170 and enters the first liquid oxygen evaporator 160 for obtaining liquid oxygen and obtaining low-pressure oxygen through self-pressurization vaporization.
The second air separation system 200 includes a second air compressor 210, a second expander 220, a second heat exchanger 240, a third rectifying tower 250, a fourth rectifying tower 260, a second liquid oxygen evaporator 270, a second condensing evaporator 280, and the like.
The outlet end of the second air compressor 210 is connected to an air duct, which is divided into a fourth air duct 211 and a fifth air duct 212. Fourth air conduit 211 is connected to third rectification column 250 after passing through second heat exchanger 240. Namely, a part of the compressed air of the second air compressor 210 is cooled by the second heat exchanger 240 in the fourth air duct 211, and is sent to the third rectification 250 for rectification after being cooled to a certain temperature. The fifth air pipe 212 is connected to the fourth rectifying tower 260 after passing through the second expander 220 and the second heat exchanger 240. Specifically, the other part of the compressed air of the second air compressor 210 enters the supercharging end of the second expander 220 through the fifth air pipeline 121 for supercharging, the supercharged compressed air enters the second heat exchanger 240 for cooling, and after being cooled to a certain temperature, the supercharged compressed air is sent to the expansion end of the second expander 220 for expansion and refrigeration, the expanded air returns to the second heat exchanger 240 for cooling again, and the cooled air is sent to the fourth rectifying tower 260 for rectification.
The third rectifying tower 250, the second condensing evaporator 280 and the fourth rectifying tower 260 are sequentially arranged from bottom to top, wherein an evaporation side liquid outlet of the second condensing evaporator 280 is connected with an evaporation side liquid inlet of the second liquid oxygen evaporator 270. The liquid oxygen obtained from the bottom of the fourth rectifying tower 260 enters the second condensing evaporator 280, and a part of the liquid oxygen is extracted from the second condensing evaporator 280 and enters the second liquid oxygen evaporator 270, so as to obtain the liquid oxygen and obtain low-pressure oxygen through self-pressurization vaporization.
The first space division system 100 and the second space division system 200 are coupled via a first coupling channel 300 and a second coupling channel 400.
The inlet end of the first coupling channel 300 is connected with the outlet end of the second air compressor 210 in the second air separation system 200, then enters the first air separation system 100, passes through the first heat exchanger 130 and is connected to the first rectifying tower 140. That is, the raw material compressed air from the second air separation system 200 enters the first air separation system 100, and is cooled to a certain temperature in the first air separation system 100 by the first heat exchanger 130, and then is sent to the first rectifying tower 140 to participate in rectification.
The inlet end of the second coupling channel 400 is connected with the outlet end of the first air compressor 110 in the first air separation system 100, then enters the second air separation system 200, passes through the second heat exchanger 240 and is connected to the second liquid oxygen evaporator 270. That is, the raw material compressed air from the first air separation system 100 enters the second air separation system 200, is cooled to a certain temperature by the second heat exchanger 240 in the second air separation system 200, and then is sent to the condensation side of the second liquid oxygen evaporator 270, and is sent to the third rectifying tower 150 for rectification after being condensed by liquid oxygen in the second liquid oxygen evaporator 270.
The discharge pressure of the first air compressor 110 configuration should be higher than the discharge pressure of the second air compressor 210 configuration. The discharge pressure of the first air compressor 110 may be configured to be 720kpa (a) and the discharge pressure of the second air compressor 210 may be configured to be 560kpa (a).
The outlet ends of the first air compressor 110 and the second air compressor 210 are both provided with a pretreatment system for precooling, drying and purifying the compressed raw air, and the like, so that the obtained compressed air is clean and dry.
When the air-cooled air separation system operates, the first air compressor 110 with higher exhaust pressure is configured to provide pressure air for the liquid oxygen heat exchangers of the two air separation systems so as to exchange heat with low-pressure liquid oxygen; the second air compressor 210 with lower exhaust pressure is configured to provide low-pressure air required for rectification for the two sets of air separation systems. In other words, in the two sets of air separation systems, the operating requirements of the two sets of air separation systems can be met only by configuring the first air compressor 110 with higher exhaust pressure, and compared with the traditional process, the configuration of the second air compressor 210 in the second set of air separation system 200 is reduced, so that the purposes of reducing the operating energy consumption and improving the economic benefit are achieved.
The operation method of the air separation plant includes a first operation mode in which the first air separation system 100 and the second air separation system 200 are coupled to operate. Specifically, taking the oxygen pressure requirement of 220kpa (a) as an example, the first mode of operation comprises the following operational steps:
step S100: the first coupling path 300 and the second coupling path 400 are open and both coupling paths are in use.
Step S200: the first air separation system 100 operates to compress the feed air to a pressure of about 720kpa (a) via the first air compressor 110 and to obtain clean and dry compressed air a after treatment via the pre-treatment system, wherein the pressure of the compressed air a is about 695kpa (a).
Step S210: the first part of the compressed air a enters the second air separation system 200 through the second coupling channel 400, is cooled by the second heat exchanger 240 in the second air separation system 200, is sent to the condensation side of the second liquid oxygen evaporator 270 after being cooled to a certain temperature, and is sent to the third rectifying tower for rectification after being condensed by low-pressure liquid oxygen.
Step S220: the second part of the compressed air a enters the first air pipeline 111, is cooled by the first heat exchanger 130, is sent to the condensation side of the first liquid oxygen evaporator 160 after being cooled to a certain temperature, is sent to the first rectifying tower 140 after being condensed by the liquid oxygen in the first liquid oxygen evaporator 160 for rectification.
Step S230: the third part of the compressed air a enters the second air pipeline 112, is pressurized by the compression end of the first expander 120, enters the first heat exchanger 130 for cooling after being pressurized, is sent to the expansion end of the first expander 120 for expansion and refrigeration after being cooled to a certain temperature, returns to the first heat exchanger for cooling, and is sent to the second rectifying tower 150 for rectification after being cooled.
Step S300: the second air separation system 200 operates simultaneously with the first air separation system 100; the raw air is compressed by the second air compressor 210 to a pressure of about 560kpa (a) and is processed by the pre-treatment system to obtain clean and dry compressed air B, which has a pressure of about 535kpa (a).
Step S310: the first part of the compressed air B enters the first air separation system 100 through the first coupling channel 300, and is cooled by the first heat exchanger 130 in the first air separation system 100 and then sent to the first rectifying tower 140 to be rectified.
Step S320: the second part of the compressed air B enters the fourth air pipe 211, is cooled by the second heat exchanger 240, and is sent to the third rectifying tower 250 to be rectified after being cooled to a certain temperature.
Step S330: the third part of the compressed air B enters the fifth air pipeline 212, is pressurized by the compression end of the second expander 230, enters the second heat exchanger 240 after being pressurized, is cooled to a certain temperature, is sent to the expansion end of the second expander 230 for expansion and refrigeration, returns to the second heat exchanger 240 for re-cooling, and is sent to the fourth rectifying tower 260 for rectification.
Further comprising step S240: the liquid oxygen obtained from the bottom of the second rectifying tower 150 enters the first condensing evaporator 170, and a part of the liquid oxygen is pumped to the evaporation side of the first liquid oxygen evaporator 160 to exchange heat with the second part of the compressed air a, so as to prepare low-pressure oxygen and liquid oxygen.
Correspondingly, the method also comprises the step S340: the liquid oxygen obtained from the bottom of the fourth rectifying tower 260 enters the second condensing evaporator 280, and a part of the liquid oxygen is pumped to the evaporation side of the second liquid oxygen evaporator 270 to exchange heat with the first part of the compressed air a to prepare low-pressure oxygen and liquid oxygen.
Example two
As shown in fig. 2, the present embodiment provides an air separation plant for producing low-pressure oxygen, which is different from the air separation plant described in the first embodiment in that the first air separation system 100 further includes a third air conduit 113, and/or the second air separation system 200 further includes a third expander 230, a sixth air conduit 213, and a seventh air conduit 214.
Wherein, the third air pipeline 113 is connected to the first air compressor 110, the first heat exchanger 130 and the first rectifying tower 140 in sequence. That is, one end of the third air duct 113 is connected to the outlet end of the first air compressor 110, exchanges heat with the first heat exchanger 130, and is then connected to the first rectifying tower 140.
The sixth air pipe 213 is connected to the outlet of the second air compressor 210, the compression end of the third expander 230, the second heat exchanger 240, and the condensation side of the second liquid oxygen evaporator 270 in sequence, and pressurizes and cools part of the compressed air of the second air compressor 210, and then sends the cooled part of the compressed air to the second liquid oxygen evaporator 270.
The seventh air duct 214 is connected to an outlet end of the second air compressor 210, the second heat exchanger 240, an expansion end of the third expander 230, the second heat exchanger 240, and the fourth rectifying tower 260 in sequence. That is, after part of the compressed air of the second air compressor 210 is cooled by the second heat exchanger 240, it is expanded and cooled by the third expander 230, and then it returns to the second heat exchanger 240 to be cooled again, and after cooled again, it is sent to the fourth rectifying tower 260 to participate in rectification.
The third air duct 113, the fifth air duct 212, the sixth air duct 213, the seventh air duct 214, the first coupling passage 300, and the second coupling passage 400 are all provided with a shut-off valve 500.
After entering the first air separation system 100, the first coupling channel 300 can be connected and merged with the third air pipeline 113, sharing a pipeline. The third air conduit 113 is provided with a shut-off valve 500 prior to connection to the junction, the shut-off valves 500 on the first coupling channel 300 and the third air conduit 113 being alternatively opened and not simultaneously opened.
Second coupling passage 400, after entering second air separation system 200, may join sixth air conduit 213 at a junction located after the pressure side of third expander 230 and before entering second heat exchanger 240 in sixth air conduit 213. The fifth air conduit 212 joins the seventh air conduit 214 after the pressurized end of the second expander 220. The second coupling passage 400 and the fifth air duct 212 are not operated simultaneously with the sixth air duct 213 and the seventh air duct 214.
The first coupling channel 300 and the third air pipeline 113, the second coupling channel 400 and the sixth air pipeline 213, and the fifth air pipeline 212 and the seventh air pipeline 214 are partially arranged to be converged to share the pipeline, so that the pipeline arrangement is effectively simplified, the pipe consumption is reduced, and the later maintenance is facilitated.
In the air separation device of the embodiment, the two sets of air separation systems can be operated in a coupling mode or can be operated independently. To ensure that both modes of operation are operating properly, it is preferred that the discharge pressure of the first air compressor 110 be 720kPa (A) and the discharge pressure of the second air compressor 210 be 605kPa (A).
The operation method of the air separation device of the embodiment includes two operation modes, namely a first operation mode and a second operation mode.
The first operation mode is a coupling operation mode of the first air separation system 100 and the second air separation system 200, and the specific operation method refers to the description in the first embodiment. In the first operating mode, the third air line 113, the sixth air line 213, the seventh air line 214 and the third expansion machine 230 are all closed.
The second operation mode is a mode in which the first air separation system 100 and the second air separation system 200 are independently operated alternatively or independently operated simultaneously. Specifically, taking the oxygen pressure requirement of 220kpa (a) as an example, the second operating mode includes the following operating steps:
step M100: the first coupling path 300 and the second coupling path 400 are closed, and the first air separation system 100 and the second air separation system 200 are independent of each other, are operated alternatively, or are operated independently at the same time.
Step M200: the first air separation system 100 operates independently, and the raw air is compressed by the first air compressor 110 to a pressure of about 720kpa (a), and is pre-cooled and dried and purified by the pre-treatment system to obtain clean and dry compressed air C, wherein the pressure of the compressed air C is about 695kpa (a).
Step M210: the first part of the compressed air C enters the third air pipeline 113, is cooled by the first heat exchanger 130, and is sent to the first rectifying tower 140 for rectification after being cooled.
Step M220: the second part of the compressed air C enters the first air pipeline 111, is cooled by the first heat exchanger 130, enters the condensation side of the first liquid oxygen evaporator 160 after being cooled, and enters the first rectifying tower 140 for rectification after being condensed by the liquid oxygen.
Step M230: the third part of the compressed air C enters the second air pipeline 112, and then sequentially enters the compression end of the first expander 120 for pressurization, enters the first heat exchanger 130 for cooling after pressurization, enters the expansion end of the first expander 120 for expansion and refrigeration after cooling, returns to the first heat exchanger 130 for cooling again after expansion, and enters the second rectifying tower 150 for rectification after cooling again.
And/or the presence of a gas in the gas,
step M300: the second air separation system 200 operates independently, and the raw air is compressed by the second air compressor 210 to a pressure of about 605kpa (a), and is precooled and dried and purified by the pretreatment system to obtain dry and clean compressed air D, wherein the pressure of the compressed air D is about 575kpa (a).
Step M310: the first part of the compressed air D enters the fourth air pipeline 211, is cooled by the second heat exchanger 240, and is sent to the third rectifying tower 250 for rectification after being cooled to a certain temperature.
Step M320: the second part of the compressed air D enters the sixth air pipeline 213, is pressurized to 695kpa (a) through the pressurizing end of the third expander 230, is cooled by the second heat exchanger 240, is cooled to a certain temperature, is sent to the condensing side of the second liquid oxygen evaporator 270, is condensed by liquid oxygen, and is sent to the third rectifying tower 250 for rectification.
Step M330: the third part of the compressed air D enters the seventh air pipeline 214, is cooled to a certain temperature by the second heat exchanger 240, then is sent to the expansion end of the third expander 230 for expansion and refrigeration, returns to the second heat exchanger 240 for cooling again after expansion, and then is sent to the fourth rectifying tower 260 for rectification.
The second expander 220 and the third expander 230 are two expanders with different configurations, which have different functions in the process and are respectively coupled with the second heat exchanger 240. The second expander 220 meets the requirement when the second air separation system 200 is operated in coupling with the first air separation system 100 (first operation mode), and the third expander 230 meets the requirement when the second air separation system 200 is operated independently.
As shown in Table 1, the oxygen production rate was 2500Nm in the second air separation system 200 3 H, oxygen purity 99.6% and pressure 220kPa (A) as an example, and compares the operation conditions of a traditional air separation system and the second air separation system 200 in the application.
Table 1 comparison of the second air separation system with the conventional air separation system
Figure 437893DEST_PATH_IMAGE001
As can be seen from Table 1, when the two air separation systems are operated in a coupling mode, the air pressure of the raw material of the second air separation system 200 is reduced by about 160kPa compared with that of the traditional air separation system, the compression power of the raw material air is reduced by more than 10%, and the energy-saving effect is obvious.
The two air separation systems can independently operate, when the first air separation system 100 is stopped for maintenance, the second air separation system 200 can independently operate, and when the second air separation system 200 independently operates, the compression power of raw air is lower than that of a traditional air separation system.
In summary, in the present application, a first air separation system 100 (an original conventional air separation system) is coupled with a second air separation system 200 (a newly-built air separation system), under the condition that the investment of power equipment is not additionally increased, a first air compressor 110 with a higher pressure and matched with the first air separation system 100 can provide pressure air for liquid oxygen heat exchangers of two sets of air separation systems, and a second air compressor 210 with a lower pressure and matched with the second air separation system 200 can provide low-pressure air required for rectification for the two sets of air separation systems, so that the problem that the operation energy consumption is high when a higher-pressure air compressor needs to be configured in a newly-built air separation system according to a conventional scheme is solved, the operation energy consumption is reduced when the second air separation system 200 is coupled or independently operated, and the economic benefit can be effectively improved.
The scope of the present application shall be defined by the appended claims, and the above description is only an exemplary embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be made by those skilled in the art within the technical scope of the present application disclosed in the present application without inventive work shall be covered by the scope of the present application.

Claims (10)

1. The utility model provides a prepare air separation plant of low pressure oxygen which characterized in that includes first air separation system and second air separation system:
the first air separation system comprises a first air compressor, a first expander, a first heat exchanger, a first rectifying tower, a second rectifying tower, a first liquid oxygen evaporator, a first air pipeline and a second air pipeline;
the first air pipeline and the second air pipeline are both connected with the outlet end of the first air compressor, the first air pipeline is connected to the first liquid oxygen evaporator after passing through the first heat exchanger, and the second air pipeline is connected to the second rectifying tower after passing through the first expander and the first heat exchanger;
the second air separation system comprises a second air compressor, a second expander, a second heat exchanger, a third rectifying tower, a fourth rectifying tower, a second liquid oxygen evaporator, a fourth air pipeline and a fifth air pipeline;
the fourth air pipeline and the fifth air pipeline are both connected with the outlet end of the second air compressor; the fourth air pipeline is connected to the third rectifying tower through the second heat exchanger; the fifth air pipeline is connected to the fourth rectifying tower after passing through the second expander and the second heat exchanger;
the first space division system and the second space division system are connected through a first coupling channel and a second coupling channel;
the inlet end of the first coupling channel is connected with the second air compressor and is connected to the first rectifying tower through the first heat exchanger; the inlet end of the second coupling channel is connected with the first air compressor and is connected to the second liquid oxygen evaporator through the second heat exchanger;
the exhaust pressure of the first air compressor is higher than that of the second air compressor.
2. The air separation plant for producing low pressure oxygen of claim 1 wherein the first air separation system further comprises a third air conduit, the third air conduit connecting in sequence the first air compressor, the first heat exchanger and the first rectification column;
and/or the presence of a gas in the gas,
the second air separation system further comprises a third expander, a sixth air conduit, and a seventh air conduit;
the sixth air pipeline is sequentially connected with the second air compressor, the compression end of the third expansion machine, the second heat exchanger and the second liquid oxygen evaporator;
and the seventh air pipeline is sequentially connected with the second air compressor, the second heat exchanger, the expansion end of the third expander, the second heat exchanger and the fourth rectifying tower.
3. The air separation plant for producing low pressure oxygen of claim 2 wherein the third air line, the fifth air line, the sixth air line, the seventh air line, the first coupling passage and the second coupling passage are provided with shut-off valves.
4. An air separation plant for producing low pressure oxygen as claimed in claim 3 wherein said first coupling passage and said third air line, said second coupling passage and said sixth air line, and said fifth air line and said seventh air line may partially merge into a common line.
5. An air separation plant for producing low pressure oxygen as claimed in any one of claims 1 to 4 wherein the discharge pressure of the first air compressor is 700 to 720kPa and the discharge pressure of the second air compressor is 560 to 620 kPa.
6. An air separation plant for the production of low pressure oxygen as claimed in claim 2 wherein the second expander and third expander are operated differently and not simultaneously.
7. An air separation plant for producing low pressure oxygen as claimed in any one of claims 1 to 3 wherein:
the first air separation system further comprises a first condensation evaporator, the first rectifying tower, the first condensation evaporator and the second rectifying tower are sequentially arranged from bottom to top, and an evaporation side liquid outlet of the first condensation evaporator is connected with an evaporation side of the first liquid oxygen evaporator;
the second air separation system further comprises a second condensation evaporator, the third rectifying tower, the second condensation evaporator and the fourth rectifying tower are sequentially arranged from bottom to top, and an evaporation side liquid outlet of the second condensation evaporator is connected with an evaporation side of the second liquid oxygen evaporator.
8. An air separation plant operating method for producing low pressure oxygen, characterized in that it is an air separation plant according to any one of claims 1 to 7, said operating method comprising a first operating mode comprising the steps of:
step S100: opening a first coupling channel and a second coupling channel;
step S200: the first air separation system operates, and raw material air is compressed by a first air compressor to obtain compressed air A;
step S210: a first part of the compressed air A enters a second coupling channel, is cooled by a second heat exchanger and then is sent to a condensation side of a second liquid oxygen evaporator;
step S220: a second part of the compressed air A enters a first air pipeline, is cooled by a first heat exchanger and then is sent to a condensation side of a first liquid oxygen evaporator;
step S230: the third part of the compressed air A enters a second air pipeline, sequentially passes through the compression end of the first expander, the first heat exchanger, the expansion end of the first expander and the first heat exchanger, and then is sent to a second rectifying tower to participate in rectification;
step S300: the second air separation system operates, and raw air is compressed by a second air compressor to obtain compressed air B;
step S310: a first part of the compressed air B enters a first coupling channel, is cooled by a first heat exchanger and then is sent to a first rectifying tower to participate in rectification;
step S320: a second part of the compressed air B enters a fourth air pipeline, is cooled by a second heat exchanger and then is sent to a third rectifying tower to participate in rectification;
step S330: and the third part of the compressed air B enters a fifth air pipeline, sequentially enters the compression end of the second expander, the second heat exchanger, the expansion end of the second expander and the second heat exchanger, and then is sent to a fourth rectifying tower to participate in rectification.
9. The method for operating an air separation plant for the production of low pressure oxygen according to claim 8, wherein the air separation plant is an air separation plant according to any one of claims 2 to 4, the method further comprising a second mode of operation comprising the steps of:
step M100: closing the first coupling channel and the second coupling channel;
step M200: the first air separation system operates, and raw air is compressed by a first air compressor to obtain compressed air C;
step M210: a first part of the compressed air C enters a third air pipeline, is cooled by a first heat exchanger and then is sent to a first rectifying tower to participate in rectification;
step M220: a second part of the compressed air C enters a first air pipeline, is cooled by a first heat exchanger and then is sent to a condensation side of a first liquid oxygen evaporator;
step M230: the third part of the compressed air C enters a second air pipeline, is sequentially processed by a compression end of a first expander, a first heat exchanger, an expansion end of the first expander and the first heat exchanger, and then is sent to a second rectifying tower to participate in rectification;
and/or the presence of a gas in the gas,
step M300: the second air separation system operates, and raw air is compressed by a second air compressor to obtain compressed air D;
step M310: a first part of the compressed air D enters a fourth air pipeline, is cooled by a second heat exchanger and then is sent to a third rectifying tower to participate in rectification;
step M320: a second part of the compressed air D enters a sixth air pipeline, is sequentially pressurized by a compression end of a third expander and cooled by a second heat exchanger, and then is sent to a condensation side of a second liquid oxygen evaporator;
step M330: and the third part of the compressed air D enters a seventh air pipeline, sequentially passes through the second heat exchanger, the expansion end of the third expansion machine and the second heat exchanger, and then is sent to a fourth rectifying tower to participate in rectification.
10. The method of operating an air separation plant for the production of low pressure oxygen of claim 9 wherein in the first mode of operation, the third air conduit, the sixth air conduit, the seventh air conduit and the third expander are all in a closed state.
CN202210435203.8A 2022-04-24 2022-04-24 Air separation device for preparing low-pressure oxygen and operation method Pending CN114838560A (en)

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Application Number Priority Date Filing Date Title
CN202210435203.8A CN114838560A (en) 2022-04-24 2022-04-24 Air separation device for preparing low-pressure oxygen and operation method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210435203.8A CN114838560A (en) 2022-04-24 2022-04-24 Air separation device for preparing low-pressure oxygen and operation method

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Publication Number Publication Date
CN114838560A true CN114838560A (en) 2022-08-02

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Country Link
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