CN109442867B - Device and method for preparing pure nitrogen by external pressurization and internal liquefaction - Google Patents
Device and method for preparing pure nitrogen by external pressurization and internal liquefaction Download PDFInfo
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- CN109442867B CN109442867B CN201811567023.5A CN201811567023A CN109442867B CN 109442867 B CN109442867 B CN 109442867B CN 201811567023 A CN201811567023 A CN 201811567023A CN 109442867 B CN109442867 B CN 109442867B
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 331
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 164
- 238000000034 method Methods 0.000 title abstract description 6
- 239000007788 liquid Substances 0.000 claims abstract description 80
- 239000002808 molecular sieve Substances 0.000 claims abstract description 20
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000006096 absorbing agent Substances 0.000 claims abstract description 8
- 238000002360 preparation method Methods 0.000 claims abstract description 6
- 239000002994 raw material Substances 0.000 claims description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 19
- 239000001301 oxygen Substances 0.000 claims description 19
- 229910052760 oxygen Inorganic materials 0.000 claims description 19
- 238000001816 cooling Methods 0.000 claims description 9
- 238000003303 reheating Methods 0.000 claims description 9
- 238000010992 reflux Methods 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 5
- 239000000428 dust Substances 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 4
- 239000007789 gas Substances 0.000 claims description 3
- 238000000746 purification Methods 0.000 claims description 3
- 229920006395 saturated elastomer Polymers 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 2
- 238000009833 condensation Methods 0.000 abstract description 6
- 230000005494 condensation Effects 0.000 abstract description 6
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 238000012423 maintenance Methods 0.000 abstract description 2
- 238000005057 refrigeration Methods 0.000 abstract description 2
- 239000002699 waste material Substances 0.000 abstract description 2
- 238000004519 manufacturing process Methods 0.000 description 10
- 239000000126 substance Substances 0.000 description 3
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
- F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
-
- 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
- F25J3/0228—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 characterised by the separated product stream
- F25J3/028—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 characterised by the separated product stream separation of noble gases
- F25J3/029—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 characterised by the separated product stream separation of noble gases of helium
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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
- F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
- F25J3/04157—Afterstage cooling and so-called "pre-cooling" of the feed air upstream the air purification unit and main heat exchange line
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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
- F25J3/04406—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system
- F25J3/04412—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
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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
- F25J3/04406—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
- F25J3/04424—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 without thermally coupled high and low pressure columns, i.e. a so-called split columns
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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
- F25J2200/00—Processes or apparatus using separation by rectification
- F25J2200/40—Features relating to the provision of boil-up in the bottom of a 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
- F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
- F25J2230/52—Processes or apparatus involving steps for increasing the pressure of gaseous process streams the fluid being oxygen enriched compared to air, e.g. "crude oxygen"
Abstract
The invention discloses an external pressurization and internal liquefaction pure nitrogen preparation device which comprises a filter, a turbine air compressor, an air precooling unit, an alternately used molecular sieve absorber, an electric heater, a main heat exchanger, a pressurization expander, a rectifying tower I, a rectifying tower II, a condensation evaporator I, a condensation evaporator II, a subcooler, a liquefier and a supercharger. The invention also discloses a method for preparing the pure nitrogen by external pressurization and internal liquefaction. The invention adopts the waste nitrogen back flow expansion refrigeration, the pressure utilization efficiency is high, and the energy consumption of the device is low; the double towers are connected in parallel to prepare nitrogen, the pressure of the upper tower can be higher or lower than that of the lower tower, two nitrogen products with the same pressure grade or different pressure grades can be prepared simultaneously, and partial liquid nitrogen products can be prepared; the internal liquefier and the external supercharger are arranged outside the cold box, so that the maintenance and the overhaul are convenient, the internal liquefier is arranged inside the cold box, the cold loss is small, and meanwhile, the external supercharger is not limited in shape selection, so that the application range of the invention can be greatly increased.
Description
Technical Field
The invention relates to the technical field of air separation, in particular to an external pressurization internal liquefaction pure nitrogen preparation device and method.
Background
With the technical development and innovation of industries such as chemical industry, electronics, new materials, porcelain steel industry, glass and the like, the demand for nitrogen is rapidly increased, and simultaneously, higher requirements on the purity of the nitrogen are also provided.
The current commercial pure nitrogen facilities on the market fall into two categories: single tower nitrogen production and double tower nitrogen production. The single-tower nitrogen production is smooth, and the nitrogen gas with certain pressure can be directly used by users, and the process has the advantages of simple structure, low extraction rate of the device, high unit consumption of the product and inapplicability to the requirement of large-scale nitrogen consumption; the double-tower nitrogen production is divided into a normal pressure nitrogen production process and a pressurized nitrogen production process, wherein the normal pressure nitrogen production process can be used for producing normal pressure nitrogen or low-pressure nitrogen with the pressure of 0.1-0.2MpaG, the device extraction rate is high, the energy consumption is lower than that of the single-tower nitrogen production process, but because the product pressure is lower, the product nitrogen can meet the requirement of a user on the nitrogen pressure after being compressed by a nitrogen compressor, the pressurized nitrogen production process is generally a liquid nitrogen pump production process, and the nitrogen quantity is less than 4500Nm 3 In the air separation device of/h, the liquid nitrogen pump is difficult to select, and meanwhile, as the liquid nitrogen pump is generally placed in the cold box, once the liquid nitrogen pump fails, the cold box must be frosted, so that the liquid nitrogen pump is generally selected to be arranged as an inlet liquid pump and is used for one.
Disclosure of Invention
The invention aims to provide an external pressurization internal liquefaction pure nitrogen preparation device and method, which are used for solving the defects in the prior art.
The invention adopts the following technical scheme:
an external pressurizing internal liquefying pure nitrogen preparing device comprises a filter, a turbine air compressor, an air precooling machine set, a molecular sieve absorber, an electric heater, a main heat exchanger, a pressurizing expansion machine, a rectifying tower I, a rectifying tower II, a condensing evaporator I, a condensing evaporator II, a subcooler, a liquefier and a supercharger,
the device comprises a filter, a turbine air compressor, an air precooling unit, a molecular sieve adsorber, an electric heater and a supercharger which are alternately used, wherein the filter, the turbine air compressor, the air precooling unit, the molecular sieve adsorber, the electric heater and the supercharger are arranged outside a cold box;
the filter, the turbine air compressor, the air precooling unit and the alternately used molecular sieve adsorbers are sequentially connected, the alternately used molecular sieve adsorbers are connected with a main heat exchanger, and the main heat exchanger is connected with a raw material air inlet at the bottom of the rectifying tower I;
the pressure nitrogen outlet at the top of the rectifying tower I is respectively connected with a main heat exchanger and a condensing evaporator I, and the main heat exchanger is connected with an external pipeline to provide pressure nitrogen products; the liquid nitrogen outlet of the condensing evaporator I is respectively connected with the top of the rectifying tower I and a liquid nitrogen storage tank outside the cold box, wherein an angle type cold valve is arranged on a connecting pipeline between the liquid nitrogen outlet of the condensing evaporator I and the top of the rectifying tower I;
the liquid-air outlet at the bottom of the rectifying tower I is connected with a subcooler, the subcooler is respectively connected with a condensing evaporator I and a rectifying tower II, a throttle valve is arranged on a connecting pipeline of the subcooler and the condensing evaporator I, and a throttle valve is arranged on a connecting pipeline of the subcooler and the rectifying tower II; the dirty nitrogen outlet of the condensing evaporator I is connected with a liquefier, the liquefier is connected with a booster, the booster is connected with the liquefier, the liquefier is connected with the bottom of the rectifying tower II, and a throttle valve is arranged on a connecting pipeline between the liquefier and the bottom of the rectifying tower II;
the pressure nitrogen outlet at the top of the rectifying tower II is respectively connected with a main heat exchanger and a condensing evaporator II, the main heat exchanger is connected with an external pipeline to provide pressure nitrogen products, and the liquid nitrogen outlet of the condensing evaporator II is connected with the top of the rectifying tower II;
the oxygen-enriched liquid air outlet at the bottom of the rectifying tower II is connected with a condensing evaporator II, a throttle valve is arranged on a connecting pipeline between the oxygen-enriched liquid air outlet at the bottom of the rectifying tower II and the condensing evaporator II, a dirty nitrogen outlet of the condensing evaporator II is connected with a subcooler, the subcooler is connected with a main heat exchanger, a part of reheating outlet of the main heat exchanger is connected with a booster expander, the booster expander is connected with the main heat exchanger, the main heat exchanger is respectively connected with an electric heater and an external emptying pipeline, and the electric heater is connected with a molecular sieve adsorber used alternately.
The preparation method of the external pressurizing and internal liquefying pure nitrogen comprises the following steps:
step one, filtering raw material air through a filter to remove dust and mechanical impurities, and then enabling the raw material air to enter a turbine air compressor to compress the air to a set pressure; then, the mixture is precooled by an air precooling unit and enters an alternately used molecular sieve absorber for purification;
secondly, using part of purified raw material air for instrument air, and cooling the rest of the raw material air into a main heat exchanger to be saturated and to be wet to a certain extent, and then entering the bottom of a rectifying tower I to participate in rectification;
step three, air is separated into pressure nitrogen and liquid air after being rectified by a rectifying tower I; the pressure nitrogen is divided into two streams, one stream is directly led out of a cold box after reheating by a main heat exchanger to serve as a product for a user, the other stream is led into a condensing evaporator I to exchange heat with liquid air, the pressure nitrogen is condensed into liquid nitrogen, part of the liquid nitrogen is led out to serve as the product for the user, and the rest of the liquid nitrogen is led into a rectifying tower I to serve as reflux liquid; the liquid air is supercooled by a supercooler and then divided into two strands, one strand is throttled and then is introduced into a rectifying tower II to participate in rectification, the other strand is throttled and then enters a condensing evaporator I to be used as a cold source for heat exchange with pressure nitrogen, the liquid air is gasified into dirty nitrogen, the dirty nitrogen is reheated by a liquefier and then is discharged out of a cold box, the dirty nitrogen is pressurized by a booster and then returns to the liquefier, the pressurized dirty nitrogen and the dirty nitrogen are subjected to heat exchange, the pressurized dirty nitrogen is partially liquefied, and the throttled dirty nitrogen is introduced into the rectifying tower II to participate in rectification;
step four, partially liquefied dirty nitrogen and liquid air introduced by a rectifying tower I are separated into oxygen-enriched liquid air and pressure nitrogen after being rectified by a rectifying tower II, the pressure nitrogen is divided into two streams, one stream is directly led out and is reheated by a main heat exchanger and then is discharged out of a cold box to be used as a product for a user, the other stream is led into a condensing evaporator II to exchange heat with the oxygen-enriched liquid air, the pressure nitrogen is condensed into liquid nitrogen, and the liquid nitrogen is led into the rectifying tower II to be used as reflux liquid; the oxygen-enriched liquid air is throttled and then is introduced into a condensing evaporator II to be used as a cold source for heat exchange with pressure nitrogen, the oxygen-enriched liquid air is vaporized into dirty nitrogen by the pressure nitrogen, the dirty nitrogen is reheated by a subcooler and then is introduced into a booster expander to expand to prepare cold energy required by a cold box, the expanded dirty nitrogen is compounded by the main heat exchanger and then is discharged out of the cold box, part of the dirty nitrogen is used as regenerated gas and is heated by an electric heater and then is introduced into a molecular sieve adsorber used alternately, and the rest of the dirty nitrogen is discharged.
The invention has the beneficial effects that:
the invention adopts the waste nitrogen back flow expansion refrigeration, has high pressure utilization efficiency and low energy consumption of the device.
The invention adopts the double towers to produce nitrogen in parallel, the pressure of the upper tower can be higher or lower than that of the lower tower, two nitrogen products with the same pressure grade or different pressure grades can be produced at the same time, and partial liquid nitrogen products can be produced.
The invention is provided with the inner liquefier and the outer supercharger, the outer supercharger is arranged outside the cold box, the maintenance and the overhaul are convenient, the inner liquefier is arranged inside the cold box, the cold loss is small, and meanwhile, the outer supercharger is not limited in the aspect of selection, so that the application range of the invention can be greatly increased.
Drawings
FIG. 1 is a schematic view of the structure of the device of the present invention.
Detailed Description
The invention will be further explained with reference to examples and figures. The following examples are only illustrative of the present invention and are not intended to limit the scope of the invention.
An external pressurization and internal liquefaction pure nitrogen preparing device comprises a filter 1, a turbine air compressor 2, an air precooling machine set 3, a molecular sieve absorber 4, an electric heater 5, a main heat exchanger 6, a pressurization expander 7, a rectifying tower I8, a rectifying tower II9, a condensing evaporator I10, a condensing evaporator II11, a subcooler 12, a liquefier 13 and a supercharger 14 which are alternately used,
the device comprises a filter 1, a turbine air compressor 2, an air precooling unit 3, a molecular sieve adsorber 4, an electric heater 5 and a supercharger 14 which are alternately used, wherein the main heat exchanger 6, a booster expander 7, a rectifying tower I8, a rectifying tower II9, a condensing evaporator I10, a condensing evaporator II11, a subcooler 12 and a liquefier 13 are arranged in the cold box, the condensing evaporator I10 is arranged above the rectifying tower I8, and the condensing evaporator II11 is arranged above the rectifying tower II 9;
the filter 1, the turbine air compressor 2, the air precooling machine set 3 and the alternately used molecular sieve adsorbers 4 are sequentially connected, the alternately used molecular sieve adsorbers 4 are connected with the main heat exchanger 6, and the main heat exchanger 6 is connected with a raw material air inlet at the bottom of the rectifying tower I8;
the pressure nitrogen outlet at the top of the rectifying tower I8 is respectively connected with the main heat exchanger 6 and the condensing evaporator I10, and the main heat exchanger 6 is connected with an external pipeline to provide pressure nitrogen products; the liquid nitrogen outlet of the condensation evaporator I10 is respectively connected with the top of the rectifying tower I8 and a liquid nitrogen storage tank outside the cold box, wherein an angle type cold valve is arranged on a connecting pipeline between the liquid nitrogen outlet of the condensation evaporator I10 and the top of the rectifying tower I8;
the liquid air outlet at the bottom of the rectifying tower I8 is connected with a subcooler 12, the subcooler 12 is respectively connected with a condensing evaporator I10 and a rectifying tower II9, a connecting pipeline of the subcooler 12 and the condensing evaporator I8 is provided with a throttle valve, and a connecting pipeline of the subcooler 12 and the rectifying tower II9 is provided with a throttle valve; the dirty nitrogen outlet of the condensing evaporator I10 is connected with a liquefier 13, the liquefier 13 is connected with a booster 14, the booster 14 is connected with the liquefier 13 again, the liquefier 13 is connected with the bottom of the rectifying tower II9, and a throttle valve is arranged on a connecting pipeline between the liquefier 13 and the bottom of the rectifying tower II 9;
the pressure nitrogen outlet at the top of the rectifying tower II9 is respectively connected with the main heat exchanger 6 and the condensing evaporator II11, the main heat exchanger 6 is connected with an external pipeline to provide pressure nitrogen products, and the liquid nitrogen outlet of the condensing evaporator II11 is connected with the top of the rectifying tower II 9;
the oxygen-enriched liquid air outlet at the bottom of the rectifying tower II9 is connected with a condensing evaporator II11, a throttle valve is arranged on a connecting pipeline between the oxygen-enriched liquid air outlet at the bottom of the rectifying tower II9 and the condensing evaporator II11, a dirty nitrogen outlet of the condensing evaporator II11 is connected with a subcooler 12, the subcooler 12 is connected with a main heat exchanger 6, a part of reheating outlet of the main heat exchanger 6 is connected with a booster expander 7, the booster expander 7 is connected with the main heat exchanger 6, the main heat exchanger 6 is respectively connected with an electric heater 5 and an external emptying pipeline, and the electric heater 5 is connected with a molecular sieve absorber 4 which is alternatively used.
The functions of the above components are as follows:
a filter 1 for filtering dust and mechanical impurities in raw material air;
a turbine air compressor 2 for compressing the filtered raw air to a set pressure;
an air pre-cooling unit 3 for pre-cooling the filtered and compressed raw material air;
the molecular sieve absorber 4 is used for purifying the filtered, compressed and precooled raw material air to remove water and CO 2 、C 2 H 2 Substances such as;
an electric heater 5 for heating the contaminated nitrogen gas to regenerate the molecular sieve adsorber;
the main heat exchanger 6 is used for cooling the filtered, compressed, precooled and purified raw material air, reheating the pressure nitrogen of the rectifying tower I8, the pressure nitrogen of the rectifying tower II9 and the expanded polluted nitrogen, and partially reheating the polluted nitrogen reheated by the cooler 12;
the booster expander 7 is used for expanding the polluted nitrogen partially reheated by the main heat exchanger 6 to prepare the necessary cold energy of the cold box;
the rectifying tower I8 is used for separating raw material air subjected to filtration, compression, precooling, purification and cooling into pressure nitrogen and liquid air through low-temperature rectification;
the rectifying tower II9 is used for rectifying the partially liquefied dirty nitrogen and the liquid air introduced by the rectifying tower I8 to separate the partially liquefied dirty nitrogen into oxygen-enriched liquid air and pressure nitrogen;
the condensing evaporator I10 is used for exchanging heat between pressure nitrogen of the rectifying tower I8 and liquid air, the pressure nitrogen is condensed into liquid nitrogen, and the liquid air is vaporized into polluted nitrogen;
the condensing evaporator II11 is used for exchanging heat between pressure nitrogen of the rectifying tower II9 and oxygen-enriched liquid air, the pressure nitrogen is condensed into liquid nitrogen, and the oxygen-enriched liquid air is vaporized into polluted nitrogen;
the subcooler 12 is used for subcooling liquid air and reheating the polluted nitrogen of the condensation evaporator II 11;
the liquefier 13 is used for reheating the polluted nitrogen of the condensation evaporator I10 and partially liquefying the pressurized polluted nitrogen;
and a booster 14 for boosting the dirty nitrogen gas reheated by the liquefier 13.
The preparation method of the external pressurizing and internal liquefying pure nitrogen comprises the following steps:
step one, filtering raw material air through a filter 1 to remove dust and mechanical impurities, and then enabling the raw material air to enter a turbine air compressor 2 to compress the air to a set pressure of 0.4-1.5MpaA; then pre-cooling to 5-8deg.C by an air pre-cooling unit 3, purifying in an alternately used molecular sieve adsorber 4, and removing water and CO 2 、C 2 H 2 Substances such as;
secondly, using part of purified raw material air for instrument air (not labeled in the figure), and cooling the rest of the raw material air into a main heat exchanger 6 to be saturated and enter the bottom of a rectifying tower I8 to participate in rectification after the raw material air is certain moisture;
step three, air is separated into pressure nitrogen and liquid air after being rectified by a rectifying tower I8; the pressure nitrogen is divided into two streams, one stream is directly led out of a cold box after reheating by a main heat exchanger 6 to serve as a product for a user, the other stream is led into a condensing evaporator I10 to exchange heat with liquid air, the pressure nitrogen is condensed into liquid nitrogen, part of the liquid nitrogen is led out to serve as the product for the user, and the rest of the liquid nitrogen is led into a rectifying tower I8 to serve as reflux liquid; the liquid air is supercooled by a cooler 12 and then divided into two streams, one stream is throttled and then is introduced into a rectifying tower II9 to participate in rectification, the other stream is throttled and then enters a condensing evaporator I10 to be used as a cold source for heat exchange with pressure nitrogen, the liquid air is gasified into dirty nitrogen, the dirty nitrogen is reheated by a liquefier 13 and then is discharged out of a cold box, the liquid air is pressurized by a booster 14 and then returns to the liquefier 13, the pressurized dirty nitrogen and the dirty nitrogen are subjected to heat exchange, the pressurized dirty nitrogen is partially liquefied, and the throttled dirty nitrogen is introduced into the rectifying tower II9 to participate in rectification;
step four, partially liquefied dirty nitrogen and liquid air introduced by a rectifying tower I8 are separated into oxygen-enriched liquid air and pressure nitrogen after being rectified by a rectifying tower II9, the pressure nitrogen is divided into two streams, one stream is directly led out and is reheated by a main heat exchanger 6 and then is discharged out of a cold box to be used as a product for a user, the other stream is introduced into a condensing evaporator II11 to exchange heat with the oxygen-enriched liquid air, the pressure nitrogen is condensed into liquid nitrogen, and the liquid nitrogen is introduced into the rectifying tower II9 to be used as reflux liquid; the oxygen-enriched liquid air is throttled and then introduced into a condensing evaporator II11 to be used as a cold source for heat exchange with pressure nitrogen, the oxygen-enriched liquid air is vaporized into dirty nitrogen by the pressure nitrogen, the dirty nitrogen is reheated by a subcooler 12, the dirty nitrogen is partially reheated by a main heat exchanger 6 and then introduced into a booster expander 7 to be expanded to prepare the cold quantity required by a cold box, the expanded dirty nitrogen is compounded by the main heat exchanger 6 and then discharged out of the cold box, part of the dirty nitrogen is heated by an electric heater 5 as regenerated gas and then introduced into a molecular sieve absorber 4 used alternately, and the rest of the dirty nitrogen is discharged.
Claims (1)
1. The preparation method of the externally pressurized and internally liquefied pure nitrogen is characterized by comprising the following steps of:
step one, filtering raw material air through a filter to remove dust and mechanical impurities, and then enabling the raw material air to enter a turbine air compressor to compress the air to a set pressure; then, the mixture is precooled by an air precooling unit and enters an alternately used molecular sieve absorber for purification;
secondly, using part of purified raw material air for instrument air, and cooling the rest of the raw material air into a main heat exchanger to be saturated and to be wet to a certain extent, and then entering the bottom of a rectifying tower I to participate in rectification;
step three, air is separated into pressure nitrogen and liquid air after being rectified by a rectifying tower I; the pressure nitrogen is divided into two streams, one stream is directly led out of a cold box after reheating by a main heat exchanger to serve as a product for a user, the other stream is led into a condensing evaporator I to exchange heat with liquid air, the pressure nitrogen is condensed into liquid nitrogen, part of the liquid nitrogen is led out to serve as the product for the user, and the rest of the liquid nitrogen is led into a rectifying tower I to serve as reflux liquid; the liquid air is supercooled by a supercooler and then divided into two strands, one strand is throttled and then is introduced into a rectifying tower II to participate in rectification, the other strand is throttled and then enters a condensing evaporator I to be used as a cold source for heat exchange with pressure nitrogen, the liquid air is gasified into dirty nitrogen, the dirty nitrogen is reheated by a liquefier and then is discharged out of a cold box, the dirty nitrogen is pressurized by a booster and then returns to the liquefier, the pressurized dirty nitrogen and the dirty nitrogen are subjected to heat exchange, the pressurized dirty nitrogen is partially liquefied, and the throttled dirty nitrogen is introduced into the rectifying tower II to participate in rectification;
step four, partially liquefied dirty nitrogen and liquid air introduced by a rectifying tower I are separated into oxygen-enriched liquid air and pressure nitrogen after being rectified by a rectifying tower II, the pressure nitrogen is divided into two streams, one stream is directly led out and is reheated by a main heat exchanger and then is discharged out of a cold box to be used as a product for a user, the other stream is led into a condensing evaporator II to exchange heat with the oxygen-enriched liquid air, the pressure nitrogen is condensed into liquid nitrogen, and the liquid nitrogen is led into the rectifying tower II to be used as reflux liquid; the oxygen-enriched liquid air is throttled and then is introduced into a condensing evaporator II to be used as a cold source for heat exchange with pressure nitrogen, the oxygen-enriched liquid air is vaporized into dirty nitrogen by the pressure nitrogen, the dirty nitrogen is reheated by a subcooler and then is introduced into a booster expander to expand to prepare cold energy required by a cold box, the expanded dirty nitrogen is compounded by the main heat exchanger and then is discharged out of the cold box, part of the dirty nitrogen is used as regenerated gas and is heated by an electric heater and then is introduced into a molecular sieve adsorber used alternately, and the rest of the dirty nitrogen is discharged.
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| CN110207457B8 (en) * | 2019-06-08 | 2023-12-29 | 苏州制氧机股份有限公司 | Air separation equipment capable of preparing liquid nitrogen and application method thereof |
| CN114174747A (en) * | 2019-07-26 | 2022-03-11 | 乔治洛德方法研究和开发液化空气有限公司 | Method and apparatus for separating air by cryogenic distillation |
| CN111141110B (en) * | 2020-01-19 | 2021-05-07 | 杭州特盈能源技术发展有限公司 | Low-energy-consumption medium-pressure nitrogen preparation process |
| CN111486663B (en) * | 2020-04-08 | 2021-01-22 | 广州广钢气体能源股份有限公司 | Nitrogen making machine suitable for electronic gas factory |
| CN111412724B (en) * | 2020-04-29 | 2021-06-04 | 杭州特盈能源技术发展有限公司 | Novel low-energy-consumption pressure oxygen enrichment preparation process for kiln |
| CN113606866A (en) * | 2021-08-06 | 2021-11-05 | 苏州市兴鲁空分设备科技发展有限公司 | Device and method for preparing nitrogen by air separation |
| CN114440553A (en) * | 2022-02-18 | 2022-05-06 | 杭州制氧机集团股份有限公司 | Low-energy-consumption double-tower pure nitrogen preparation device adopting nitrogen expansion refrigeration and application method |
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