CN112556312A - Steam-driven air separation method and steam T-stage utilization system for same - Google Patents
Steam-driven air separation method and steam T-stage utilization system for same Download PDFInfo
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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
- F25J3/04333—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams
- F25J3/04351—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen
- F25J3/04357—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen and comprising a gas work expansion loop
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
- F01D15/10—Adaptations for driving, or combinations with, electric generators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22G—SUPERHEATING OF STEAM
- F22G5/00—Controlling superheat temperature
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D1/00—Steam central heating systems
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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
- F25J3/04333—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams
- F25J3/04363—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of oxygen
Abstract
The invention discloses a steam-driven air separation method and a steam T-level utilization system used for the method, compared with the traditional electrically-driven air separation, the steam turbine replaces a motor, the steam drive replaces the electric drive, and the operation cost is only about half of that of the traditional electrically-driven air separation; the operation efficiency of the whole air separation system is improved, the system operation cost is low, the energy consumption is low, and the energy is saved. The cost of oxygen and nitrogen production can be reduced by 50 percent compared with the cost of an electrically driven oxygen and nitrogen production mode; meanwhile, when the oxygen and nitrogen are prepared by the process, the efficiency and the economy of air separation are further improved, compared with the conventional air separation technology, the operation cost is reduced by about 1/2, and the system is simple to operate and convenient to operate. Due to the fact that energy consumption is reduced, energy consumption discharge of monomer oxygen yield and nitrogen yield is lower, efficiency is higher, and effective collection and cyclic utilization of intermediate steam heat energy generated by a chemical chain are achieved.
Description
Technical Field
The invention relates to a steam-driven air separation method and a steam T-stage utilization system for the method.
Background
The technologies commonly used at present for preparing oxygen and nitrogen by air separation comprise a cryogenic rectification technology, a membrane separation technology and a pressure swing adsorption technology. The cryogenic rectification technology is the most mature air separation technology at present, and the principle is that the air is liquefied by utilizing the different boiling points of nitrogen and oxygen in the air, and then the cryogenic rectification is carried out to achieve the purpose of separating the nitrogen and the oxygen, and gases such as helium, argon and the like can be extracted at the same time.
According to the related investigation, the independent oxygen production operation occupies ninety percent of the total power consumption of the enterprise for the consumption of the electric power energy, so the control of the loss of the whole energy is particularly critical for other cost control. The energy loss generated in the air separation process of the cryogenic rectification technology is generally reflected in the aspects of rectification, compression, cold loss, product purity and the like. The existing air separation mode is that a motor drives a compressor to do work to realize air separation, and electricity is obtained by driving a steam turbine and then driving a generator through a transformer, circuit remote conveying and other links, so that transmission loss exists in the process, and the problems of steam energy waste and energy waste exist simultaneously.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a steam-driven air separation method and a steam T-level utilization system for the method.
The technical scheme for solving the problems comprises the following steps: a steam driven air separation process comprising the steps of:
s1: air enters an air compressor after being filtered by an air filter to remove dust and mechanical impurities, and enters a precooling system after being compressed;
s2; after the air is cooled in a precooling system and water-soluble impurities are removed, the air enters a purification system to remove moisture, carbon dioxide and hydrocarbon;
s3: mixing the air leaving the purification system with circulating air from a cold box, entering a circulating air compressor for compression and cooling after mixing, and then dividing the compressed air into two parts; a first strand of compressed air enters the main heat exchanger, is cooled to a certain temperature by the return gas and then is pumped out, the compressed air is sent into the hot end expander for expansion refrigeration, the expanded air returns to the main heat exchanger and is mixed with part of expanded reheating air in the cold end expander, then the mixture is continuously reheated to the normal temperature, and then the mixture is taken out of the cold box as circulating air and enters the circulating compressor;
the second compressed air enters a pressurizing end of a hot end expander for pressurization, is cooled by a cooler and then enters a pressurizing end of a cold end expander, is pressurized and cooled by the cooler and then enters a main heat exchanger, and then the air is divided into a part A and a part B; after the air of the part A is cooled to the liquefaction temperature at the bottom of the main heat exchanger, reducing the pressure and the temperature through throttling, entering a vapor-liquid separator, feeding the separated liquid into the middle part of a lower tower, and feeding the separated gas into the lower part of the lower tower to participate in rectification; after entering a cold-end expander for refrigeration, the part B of air is divided into a part B1 and a part B2, the part B1 enters the bottom of the lower tower to participate in rectification, and the part B2 is reheated to normal temperature by a main heat exchanger and then is taken as circulating air to be discharged out of a cold box;
s4: rectifying the gas entering the lower part of the lower tower to obtain oxygen-enriched liquid air, lean liquid air and liquid nitrogen, wherein the liquid nitrogen is divided into a part C, a part D and a part E;
the oxygen-enriched liquid air, the lean liquid air and the liquid nitrogen of the part C are respectively led out from the bottom of the lower tower, the lower part of the lower tower and the condensing evaporator, enter the subcooler and are cooled and subcooled by the reflux nitrogen and the waste nitrogen from the upper tower; d, conveying the liquid nitrogen serving as a product into a cold box after throttling, depressurizing and cooling; e, feeding part of the liquid nitrogen into an upper tower, and rectifying the liquid nitrogen in the upper tower to obtain liquid oxygen, waste nitrogen and nitrogen gas at the bottom of a condensation evaporator, the upper part of the upper tower and the top of the upper tower respectively;
s5: the nitrogen and the polluted nitrogen are respectively pumped out from the top of the upper tower and the upper part of the upper tower to enter a subcooler, the nitrogen and the polluted nitrogen enter a main heat exchanger for heat exchange after the heat exchange, and the polluted nitrogen after the reheating is divided into an F part and a G part;
f part of the polluted nitrogen enters a molecular sieve purification system to be used as regenerated gas; and G part of polluted nitrogen and nitrogen enter a precooling system to be used as cold sources.
S6: and liquid oxygen is pumped out from the condensing evaporator, and is sent out of the cold box after being supercooled to enter the liquid oxygen storage tank. And drawing out the liquid nitrogen of the part C from the subcooler and sending the liquid nitrogen into a liquid nitrogen storage tank.
S7: extracting argon fraction gas from the lower part of the upper tower, introducing the argon fraction gas into a crude argon tower I, and introducing the argon fraction gas into a crude argon tower II after transferring heat and mass with liquid crude argon conveyed from a crude argon tower II through a circulating liquid argon pump; in the crude argon column II, a cold source of the crude argon column II is oxygen-enriched liquid air after being cooled, and oxygen components are removed from argon fraction gas after heat and mass transfer; and then the pure argon enters a pure argon tower, the top and the bottom of the pure argon tower are respectively provided with a condenser and an evaporator, a heat source and a cold source are respectively a supercooled liquid air and a throttled and cooled liquid air, the process argon is rectified in the pure argon tower to remove nitrogen components, and liquid pure argon is obtained at the bottom of the pure argon condenser.
Further, the precooling system comprises an air cooling tower and a water cooling tower which are communicated.
Further, the purification system comprises two purifiers connected in parallel, and an electric heater and a steam heater which are communicated with the purifiers;
one purifier is used for removing moisture, carbon dioxide and hydrocarbon in the precooled air, and the other purifier is used for regenerating the purifier for the waste nitrogen generated by the rectification system and heated by the electric heater and the steam heater so as to obtain the adsorption capacity again.
Further, the steam T-level utilization system comprises a power source, a low-pressure steam heating network, a first emptying silencer communicated with the power source through a branch pipeline, a discharge valve installed on a branch pipeline, a main pipeline communicated with the power source, a safety pipeline with one end communicated with the main pipeline and the other end communicated with the branch pipeline, a first safety valve installed on the safety pipeline, an air pressure turbine communicated with the main pipeline through a pipeline A, a first steam inlet emergency cut-off valve installed on the pipeline A, a booster turbine communicated with the main pipeline through a pipeline B, a second steam inlet emergency cut-off valve installed on the pipeline B, a conveying pipe communicated with the low-pressure steam heating network, a pipeline C with one end communicated with the air pressure turbine and the other end communicated with the conveying pipe, a first steam outlet merging network valve installed on the pipeline C, and a second emptying silencer communicated with the pipeline C through a pipeline D, a second safety valve installed on the pipeline D, a pipeline E with one end communicated with the pipeline D and the other end communicated with the pipeline C, a first emptying valve installed on the pipeline E, a pipeline F with one end communicated with the supercharging steam turbine and the other end communicated with the conveying pipe, a second steam discharging and net combining valve installed on the pipeline F, a third emptying silencer communicated with the pipeline F through a pipeline G, a third safety valve installed on the pipeline G, a pipeline H with one end communicated with the pipeline G and the other end communicated with the pipeline F, a second emptying valve installed on the pipeline H, a pipeline J with one end communicated with the main pipeline and the other end communicated with the conveying pipe, and a temperature and pressure reducing device installed on the pipeline J;
the power source is superheated steam generated by diluting high-concentration sulfuric acid.
Further, the superheated steam is 5.0MPa and 480 ℃.
Further, the working process of the steam T level utilization system is as follows:
s1: superheated steam enters an air pressure turbine and a supercharging turbine respectively, heat energy and pressure energy are consumed, an air compressor, a circulating air compressor and a supercharger are pushed to rotate to do work, and compressed air is compressed to the pressure required by the device;
s2: after the superheated steam consumes the heat energy and the pressure energy, the superheated steam is decompressed and cooled to enter a low-pressure steam heating network for being used by downstream users.
Further, the superheated steam is depressurized to 1.4MPa, and is cooled to 330 ℃.
The invention has the following beneficial effects: compared with the traditional electrically-driven air separation, the air separation system has the advantages that the steam turbine replaces a motor, the steam drive replaces the electric drive, and the operation cost is only about half of that of the traditional electric drive; the operation efficiency of the whole air separation system is improved, the system operation cost is low, the energy consumption is low, and the energy is saved. The cost of oxygen and nitrogen production can be reduced by 50 percent compared with the cost of an electrically driven oxygen and nitrogen production mode; meanwhile, when the oxygen and nitrogen are prepared by the process, the efficiency and the economy of air separation are further improved, compared with the conventional air separation technology, the operation cost is reduced by about 1/2, and the system is simple to operate and convenient to operate. Because the energy consumption is reduced, the monomer oxygen yield and the nitrogen yield are lower in energy consumption discharge and higher in efficiency, and the heat energy of intermediate steam generated by a chemical chain is effectively collected and recycled.
Drawings
FIG. 1 is a flow diagram of the air separation process of the present invention;
FIG. 2 is a schematic diagram of a steam T-stage utilization system according to the present invention.
Detailed Description
The invention is further described with reference to the following drawings and detailed description.
A steam driven air separation process comprising the steps of:
s1: air enters an air compressor after being filtered by an air filter to remove dust and mechanical impurities, and enters a precooling system after being compressed;
s2; the air passes through a precooling system, the precooling system comprises an air cooling tower and a water cooling tower which are communicated, the air is cooled and cooled in the air cooling tower by cooling water from the middle part of the air cooling tower and chilled water cooled by a water cooling tower, and the air is washed by water, water-soluble impurities are removed, and then the air enters a purification system to remove moisture, carbon dioxide and hydrocarbon;
the purification system comprises two purifiers connected in parallel, and an electric heater and a steam heater which are communicated with the purifiers;
one purifier is used for removing moisture, carbon dioxide and hydrocarbon in the precooled air, and the other purifier is used for regenerating the purifier for the waste nitrogen generated by the rectification system and heated by the electric heater and the steam heater to obtain the adsorption capacity again;
s3: mixing the air leaving the purification system with circulating air from a cold box, entering a circulating air compressor for compression and cooling after mixing, and then dividing the compressed air into two parts; a first strand of compressed air enters the main heat exchanger, is cooled to a certain temperature by the return gas and then is pumped out, the compressed air is sent into the hot end expander for expansion refrigeration, the expanded air returns to the main heat exchanger and is mixed with part of expanded reheating air in the cold end expander, then the mixture is continuously reheated to the normal temperature, and then the mixture is taken out of the cold box as circulating air and enters the circulating compressor;
the second compressed air enters a pressurizing end of a hot end expander for pressurization, is cooled by a cooler and then enters a pressurizing end of a cold end expander, is pressurized and cooled by the cooler and then enters a main heat exchanger, and then the air is divided into a part A and a part B; after the air of the part A is cooled to the liquefaction temperature at the bottom of the main heat exchanger, reducing the pressure and the temperature through throttling, entering a vapor-liquid separator, feeding the separated liquid into the middle part of a lower tower, and feeding the separated gas into the lower part of the lower tower to participate in rectification; after entering a cold-end expander for refrigeration, the part B of air is divided into a part B1 and a part B2, the part B1 enters the bottom of the lower tower to participate in rectification, and the part B2 is reheated to normal temperature by a main heat exchanger and then is taken as circulating air to be discharged out of a cold box;
s4: rectifying the gas entering the lower part of the lower tower to obtain oxygen-enriched liquid air, lean liquid air and liquid nitrogen, wherein the liquid nitrogen is divided into a part C, a part D and a part E;
the oxygen-enriched liquid air, the lean liquid air and the liquid nitrogen of the part C are respectively led out from the bottom of the lower tower, the lower part of the lower tower and the condensing evaporator, enter the subcooler and are cooled and subcooled by the reflux nitrogen and the waste nitrogen from the upper tower; d, conveying the liquid nitrogen serving as a product into a cold box after throttling, depressurizing and cooling; e, feeding part of the liquid nitrogen into an upper tower, and rectifying the liquid nitrogen in the upper tower to obtain liquid oxygen, waste nitrogen and nitrogen gas at the bottom of a condensation evaporator, the upper part of the upper tower and the top of the upper tower respectively;
s5: the nitrogen and the polluted nitrogen are respectively pumped out from the top of the upper tower and the upper part of the upper tower to enter a subcooler, the nitrogen and the polluted nitrogen enter a main heat exchanger for heat exchange after the heat exchange, and the polluted nitrogen after the reheating is divided into an F part and a G part;
f part of the polluted nitrogen enters a molecular sieve purification system to be used as regenerated gas; and G part of polluted nitrogen and nitrogen enter a precooling system to be used as cold sources.
S6: and liquid oxygen is pumped out from the condensing evaporator, and is sent out of the cold box after being supercooled to enter the liquid oxygen storage tank. And drawing out the liquid nitrogen of the part C from the subcooler and sending the liquid nitrogen into a liquid nitrogen storage tank.
S7: extracting argon fraction gas from the lower part of the upper tower, introducing the argon fraction gas into a crude argon tower I, and introducing the argon fraction gas into a crude argon tower II after transferring heat and mass with liquid crude argon conveyed from a crude argon tower II through a circulating liquid argon pump; in the crude argon column II, a cold source of the crude argon column II is oxygen-enriched liquid air after being cooled, and oxygen components are removed from argon fraction gas after heat and mass transfer; and then the pure argon enters a pure argon tower, the top and the bottom of the pure argon tower are respectively provided with a condenser and an evaporator, a heat source and a cold source are respectively a supercooled liquid air and a further throttled and cooled liquid air, the process argon is rectified in the pure argon tower to remove nitrogen components, and liquid pure argon is obtained at the bottom of the pure argon condenser.
The main separation process is completed in the double-stage rectifying tower which is composed of an upper tower, a lower tower and a condensing evaporator positioned between the upper tower and the lower tower. The air entering the bottom of the lower column is partially liquefied. Because the boiling point of liquid nitrogen is lower than that of liquid oxygen, the liquefied gas at the bottom of the lower tower is oxygen-enriched liquid air, and the oxygen content is generally 30-40%.
The lower tower operating pressure is higher than that of the upper tower, so that the condensation temperature of nitrogen at the top of the lower tower is higher than the boiling temperature of liquid oxygen at the bottom of the upper tower, and heat in the condensation evaporator is transferred from the inside of the pipe to the inside of the pipe and has certain heat transfer temperature difference. The condensation evaporator simultaneously plays the roles of condensation at the top of the lower tower and evaporation at the bottom of the upper tower. The air is rectified from bottom to top in the lower tower through the multi-layer tower plates to gradually increase the concentration of the volatile component nitrogen and is condensed into liquid nitrogen in the condensation evaporator tube. A part of liquid nitrogen is used as reflux liquid in the lower tower; one part of the liquid is collected in a liquid nitrogen tank and is used as the reflux liquid at the top of the upper tower after pressure reduction. The oxygen-enriched liquid air at the bottom of the lower tower enters the middle part of the upper tower and is in countercurrent contact with the gas evaporated by the condensation evaporator. The oxygen content in the down-flow liquid is increased from top to bottom and finally accumulated between the tubes of the condensing evaporator, the oxygen content can reach more than 99.6 percent, and the product oxygen is continuously evaporated and led out of the tower.
The nitrogen is extracted from the top of the upper tower, and the concentration can reach more than 99.999%. The temperature of the product nitrogen and the waste nitrogen which are discharged from the tower is lower, and the input air can be cooled through the heat exchanger to recover cold energy and can be reheated to normal temperature to be sent to users.
The air separation system provides energy by means of the steam T-level utilization system, the compressor is directly driven to work, and energy is saved to the maximum extent.
The steam T-level utilization system comprises a power source, a low-pressure steam heating network, a first emptying silencer communicated with the power source through a branch pipeline, a discharge valve arranged on a branch pipeline, a main pipeline communicated with the power source, a safety pipeline with one end communicated with the main pipeline and the other end communicated with the branch pipeline, a first safety valve arranged on the safety pipeline, an air pressure turbine communicated with the main pipeline through a pipeline A, a first steam inlet emergency cut-off valve arranged on the pipeline A, a booster turbine communicated with the main pipeline through a pipeline B, a second steam inlet emergency cut-off valve arranged on the pipeline B, a conveying pipe communicated with the low-pressure steam heating network, a pipeline C with one end communicated with the air pressure turbine and the other end communicated with the conveying pipe, a first steam discharge and network valve arranged on the pipeline C, a second emptying silencer communicated with the pipeline C through a pipeline D, and a second safety valve arranged on the pipeline D, the system comprises a pipeline E, a first emptying valve, a pipeline F, a second steam discharging and net combining valve, a third emptying silencer, a third safety valve, a pipeline H, a second emptying valve, a pipeline J and a temperature and pressure reducing device, wherein one end of the pipeline E is communicated with a pipeline D, the other end of the pipeline E is communicated with a pipeline C;
the power source is superheated steam with the pressure of 5.0MPa and the temperature of 480 ℃ generated by diluting high-concentration sulfuric acid.
The steam T level utilization system is controlled by adopting a DCS control system, the opening and closing of a valve, the opening and closing of an air pressure turbine, the opening and closing of a supercharging turbine and the like are controlled, and a plurality of pipelines, a steam inlet emergency cut-off valve, a steam exhaust grid valve and the like are matched to form interlocking protection, so that the safe operation is ensured; the device interlocking protection measures comprise: when the power source, the low-pressure steam heating network, the air pressure steam turbine or the supercharging steam turbine generate steam break, water break, power break or equipment failure to send out interlocking signals, the following interlocking protection actions are carried out:
1. the first steam inlet emergency cut-off valve and the second steam inlet emergency cut-off valve are automatically and fully closed, and the air pressure turbine and the supercharging turbine are stopped;
2. the first emptying valve and the second emptying valve are automatically and fully opened, and residual steam is discharged for pressure relief;
3. the first steam discharging grid combining valve and the second steam discharging grid combining valve are automatically and fully closed and are isolated from the heat supply network;
4. the discharge valve enters an automatic regulation state, and the regulation ensures that the steam pressure is constant, so as to prevent overpressure;
5. the steam pressure and the temperature of the low-pressure heat supply network are automatically adjusted and balanced to be constant through the temperature and pressure reducing device, so that the steam stability of downstream low-pressure steam users is guaranteed.
6. When the pressure is ultrahigh, the first safety valve, the second safety valve and the third safety valve automatically release the pressure and discharge the pressure to a safety place;
7. all the emptying valves and the safety valves are drained into the emptying silencer to be discharged, so that the discharge safety is guaranteed.
The working process of the steam T level utilization system is as follows:
s1: superheated steam enters an air pressure turbine and a supercharging turbine respectively, heat energy and pressure energy are consumed, an air compressor, a circulating air compressor and a supercharger are pushed to rotate to do work, and compressed air is compressed to the pressure required by the device;
s2: after the superheated steam consumes the heat energy and the pressure energy, the superheated steam enters a low-pressure steam heat supply network after being decompressed and cooled to 1.4MPa and 330 ℃ and is supplied to downstream users for use.
The invention adopts the T-stage utilization of steam to directly drive the steam turbine to drive the compressor, thereby realizing air separation; the traditional electric driving mode is avoided, the rapid energy conversion is directly realized, the energy conversion efficiency is improved, the rapid and efficient energy conversion is realized, the energy-saving and environment-friendly effects are realized compared with the traditional mode, no dangerous product is produced in the whole production process, and no thermal pollution is caused to realize zero energy emission; through introducing high-pressure high-temperature steam, set up many return circuits, the bypass, through centralized control system DCS, in operation real time monitoring, in case the appearance is unusual, do the unloading of steam and handle, the reliable steady operation of guarantee system.
Many other changes and modifications can be made without departing from the spirit and scope of the invention. It is to be understood that the invention is not to be limited to the specific embodiments, but only by the scope of the appended claims.
Claims (7)
1. A steam driven air separation process, comprising the steps of:
s1: air enters an air compressor after being filtered by an air filter to remove dust and mechanical impurities, and enters a precooling system after being compressed;
s2; after the air is cooled in a precooling system and water-soluble impurities are removed, the air enters a purification system to remove moisture, carbon dioxide and hydrocarbon;
s3: mixing the air leaving the purification system with circulating air from a cold box, entering a circulating air compressor for compression and cooling after mixing, and then dividing the compressed air into two parts; a first strand of compressed air enters the main heat exchanger, is cooled to a certain temperature by the return gas and then is pumped out, the compressed air is sent into the hot end expander for expansion refrigeration, the expanded air returns to the main heat exchanger and is mixed with part of expanded reheating air in the cold end expander, then the mixture is continuously reheated to the normal temperature, and then the mixture is taken out of the cold box as circulating air and enters the circulating compressor;
the second compressed air enters a pressurizing end of a hot end expander for pressurization, is cooled by a cooler and then enters a pressurizing end of a cold end expander, is pressurized and cooled by the cooler and then enters a main heat exchanger, and then the air is divided into a part A and a part B; after the air of the part A is cooled to the liquefaction temperature at the bottom of the main heat exchanger, reducing the pressure and the temperature through throttling, entering a vapor-liquid separator, feeding the separated liquid into the middle part of a lower tower, and feeding the separated gas into the lower part of the lower tower to participate in rectification; after entering a cold-end expander for refrigeration, the part B of air is divided into a part B1 and a part B2, the part B1 enters the bottom of the lower tower to participate in rectification, and the part B2 is reheated to normal temperature by a main heat exchanger and then is taken as circulating air to be discharged out of a cold box;
s4: rectifying the gas entering the lower part of the lower tower to obtain oxygen-enriched liquid air, lean liquid air and liquid nitrogen, wherein the liquid nitrogen is divided into a part C, a part D and a part E;
the oxygen-enriched liquid air, the lean liquid air and the liquid nitrogen of the part C are respectively led out from the bottom of the lower tower, the lower part of the lower tower and the condensing evaporator, enter the subcooler and are cooled and subcooled by the reflux nitrogen and the waste nitrogen from the upper tower; d, conveying the liquid nitrogen serving as a product into a cold box after throttling, depressurizing and cooling; e, feeding part of the liquid nitrogen into an upper tower, and rectifying the liquid nitrogen in the upper tower to obtain liquid oxygen, waste nitrogen and nitrogen gas at the bottom of a condensation evaporator, the upper part of the upper tower and the top of the upper tower respectively;
s5: the nitrogen and the polluted nitrogen are respectively pumped out from the top of the upper tower and the upper part of the upper tower to enter a subcooler, the nitrogen and the polluted nitrogen enter a main heat exchanger for heat exchange after the heat exchange, and the polluted nitrogen after the reheating is divided into an F part and a G part;
f part of the polluted nitrogen enters a molecular sieve purification system to be used as regenerated gas; and G part of polluted nitrogen and nitrogen enter a precooling system to be used as cold sources.
S6: and liquid oxygen is pumped out from the condensing evaporator, and is sent out of the cold box after being supercooled to enter the liquid oxygen storage tank. And drawing out the liquid nitrogen of the part C from the subcooler and sending the liquid nitrogen into a liquid nitrogen storage tank.
S7: extracting argon fraction gas from the lower part of the upper tower, introducing the argon fraction gas into a crude argon tower I, and introducing the argon fraction gas into a crude argon tower II after transferring heat and mass with liquid crude argon conveyed from a crude argon tower II through a circulating liquid argon pump; in the crude argon column II, a cold source of the crude argon column II is oxygen-enriched liquid air after being cooled, and oxygen components are removed from argon fraction gas after heat and mass transfer; and then the pure argon enters a pure argon tower, the top and the bottom of the pure argon tower are respectively provided with a condenser and an evaporator, a heat source and a cold source are respectively a supercooled liquid air and a further throttled and cooled liquid air, the process argon is rectified in the pure argon tower to remove nitrogen components, and liquid pure argon is obtained at the bottom of the pure argon condenser.
2. The steam driven air separation process of claim 1, wherein the pre-cooling system comprises an air cooling column and a water cooling column in communication.
3. The steam driven air separation process of claim 1, wherein the purification system comprises two purifiers in parallel, an electric heater in communication with the purifiers, a steam heater;
one purifier is used for removing moisture, carbon dioxide and hydrocarbon in the precooled air, and the other purifier is used for regenerating the purifier for the waste nitrogen generated by the rectification system and heated by the electric heater and the steam heater so as to obtain the adsorption capacity again.
4. A steam T stage utilization system for the steam driven air separation method as claimed in claim 1, 2 or 3, characterized in that the steam T stage utilization system comprises a power source, a low pressure steam heating network, a first discharge muffler communicated with the power source through a branch pipeline, a discharge valve installed on the branch pipeline, a main pipeline communicated with the power source, a safety pipeline having one end communicated with the main pipeline and the other end communicated with the branch pipeline, a first safety valve installed on the safety pipeline, an air pressure turbine communicated with the main pipeline through a pipeline A, a first steam inlet emergency cut-off valve installed on the pipeline A, a booster turbine communicated with the main pipeline through a pipeline B, a second steam inlet emergency cut-off valve installed on the pipeline B, a delivery pipe communicated with the low pressure steam heating network, a pipeline C having one end communicated with the air pressure turbine and the other end communicated with the delivery pipe, a first exhaust merging and exhausting valve installed on the pipeline C, a second exhaust silencer communicated with the pipeline C through the pipeline D, a second safety valve installed on the pipeline D, a pipeline E with one end communicated with the pipeline D and the other end communicated with the pipeline C, a first exhaust valve installed on the pipeline E, a pipeline F with one end communicated with the supercharging steam turbine and the other end communicated with the conveying pipe, a second exhaust merging and exhausting valve installed on the pipeline F, a third exhaust silencer communicated with the pipeline F through the pipeline G, a third safety valve installed on the pipeline G, a pipeline H with one end communicated with the pipeline G and the other end communicated with the pipeline F, a second exhaust valve installed on the pipeline H, a pipeline J with one end communicated with the main pipeline and the other end communicated with the conveying pipe, and a temperature and pressure reducing device installed on the pipeline J;
the power source is superheated steam generated by diluting high-concentration sulfuric acid.
5. The steam T stage utilization system of claim 4, wherein the superheated steam is 5.0MPa, 480 ℃.
6. The steam T-stage utilization system according to claim 4 or 5, wherein the working process of the steam T-stage utilization system is as follows:
s1: superheated steam enters an air pressure turbine and a supercharging turbine respectively, heat energy and pressure energy are consumed, an air compressor, a circulating air compressor and a supercharger are pushed to rotate to do work, and compressed air is compressed to the pressure required by the device;
s2: after the superheated steam consumes the heat energy and the pressure energy, the superheated steam is decompressed and cooled to enter a low-pressure steam heating network for being used by downstream users.
7. The steam T-stage utilization system of claim 6, wherein the superheated steam is depressurized to 1.4MPa and cooled to 330 ℃.
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