CN110567192B - Oxygen production process waste heat gradient utilization system and method - Google Patents
Oxygen production process waste heat gradient utilization system and method Download PDFInfo
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- CN110567192B CN110567192B CN201910834083.7A CN201910834083A CN110567192B CN 110567192 B CN110567192 B CN 110567192B CN 201910834083 A CN201910834083 A CN 201910834083A CN 110567192 B CN110567192 B CN 110567192B
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 78
- 239000001301 oxygen Substances 0.000 title claims abstract description 78
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 78
- 239000002918 waste heat Substances 0.000 title claims abstract description 44
- 238000000034 method Methods 0.000 title claims abstract description 39
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 35
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 215
- 238000003860 storage Methods 0.000 claims abstract description 65
- 238000007906 compression Methods 0.000 claims abstract description 48
- 230000006835 compression Effects 0.000 claims abstract description 48
- 238000010438 heat treatment Methods 0.000 claims abstract description 39
- 238000005057 refrigeration Methods 0.000 claims abstract description 36
- 238000001816 cooling Methods 0.000 claims abstract description 28
- 239000007788 liquid Substances 0.000 claims abstract description 25
- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 claims description 29
- 230000001105 regulatory effect Effects 0.000 claims description 26
- 239000000498 cooling water Substances 0.000 claims description 24
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 17
- 238000004064 recycling Methods 0.000 claims description 9
- 239000013589 supplement Substances 0.000 claims description 6
- 229910000831 Steel Inorganic materials 0.000 abstract description 4
- 239000010959 steel Substances 0.000 abstract description 4
- 238000004134 energy conservation Methods 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 16
- 238000011084 recovery Methods 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000005338 heat storage Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000036284 oxygen consumption Effects 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000005381 potential energy Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
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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
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B27/00—Machines, plants or systems, using particular sources of energy
- F25B27/02—Machines, plants or systems, using particular sources of energy using waste heat, e.g. from internal-combustion engines
-
- 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
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
-
- 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
- F25J5/00—Arrangements of cold exchangers or cold accumulators in separation or liquefaction plants
- F25J5/002—Arrangements of cold exchangers or cold accumulators in separation or liquefaction plants for continuously recuperating cold, i.e. in a so-called recuperative heat exchanger
-
- 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
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/07—Details of compressors or related parts
- F25B2400/075—Details of compressors or related parts with parallel compressors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A30/00—Adapting or protecting infrastructure or their operation
- Y02A30/27—Relating to heating, ventilation or air conditioning [HVAC] technologies
- Y02A30/274—Relating to heating, ventilation or air conditioning [HVAC] technologies using waste energy, e.g. from internal combustion engine
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- Mechanical Engineering (AREA)
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- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Heat-Pump Type And Storage Water Heaters (AREA)
Abstract
The invention relates to the technical field of energy conservation in the steel industry, in particular to a gradient utilization system and method for waste heat in an oxygen production process. The system comprises an air compressor primary compression device, an air compressor secondary compression device, an air compressor tertiary compression device, a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, an oxygen generator, a refrigeration user, a heating user, a heat pump unit, a cooling tower, a water supply tank, a high-temperature water storage tank, a low-temperature liquid heat exchanger, a flow meter and various valves connected among the devices. The cascade utilization method of the waste heat in the oxygen production process comprises two operation models, namely a non-operation mode of a low-temperature heat exchanger; and the second is the operation mode of the low-temperature heat exchanger. The waste heat of the oxygen production process can be used for production and living heat supply of the oxygen process in a gradient manner, and the waste heat of the air compressor is utilized to effectively adapt to the demand fluctuation of a heat user.
Description
Technical Field
The invention relates to the technical field of energy conservation in the steel industry, in particular to a gradient utilization system and method for waste heat in an oxygen production process.
Background
Iron and steel enterprises need a large amount of energy media such as high-purity oxygen, nitrogen and the like in the smelting production process, so that large iron and steel enterprises usually have an oxygen production process, and are provided with a plurality of oxygen generators and oxygen pipe networks, and oxygen produced by the oxygen generators is sent to each oxygen consuming user through the pipe networks; when a trip fault occurs in a certain oxygen generator in the oxygen generation process and the amount of generated oxygen cannot meet the requirements of downstream oxygen consumption users, the pressure of an oxygen pipe network is insufficient, and the trip fault of the oxygen generator generally needs 15-20 hours to recover; in order to ensure stable production of downstream oxygen consuming users, a production plant is generally provided with a plurality of liquid oxygen tanks for storing a large amount of liquid oxygen, when the pressure of an oxygen pipe network is insufficient, the liquid oxygen stored in the liquid oxygen tanks for later use can be heated into normal-temperature gas to be conveyed into the oxygen pipe network, namely, the liquid oxygen is heated from minus 183 ℃ to 20 ℃ by a heat source heating mode and is conveyed into the pipe network to be supplied to the oxygen consuming users. Because the heating of the low-temperature liquid oxygen belongs to the unplanned and intermittent heating, and the instant heating quantity is large. At present, most domestic oxygen plants adopt a water bath type heat exchange mode to heat liquid oxygen, a heating heat source is generally steam, the heating mode can consume a large amount of high-quality energy, and the production cost of enterprises is increased.
A plurality of air compressors are arranged in the oxygen production process; when the air compressor is in operation, the air compressor is really used for increasing the electric energy consumed by air potential energy, and only occupies a small part, about 15%, of the total electric energy consumption. About 85% of the electricity consumed is converted to heat in the compressed gas and is discharged to the air by air or water cooling. If the waste heat of the compressed gas is recovered and is used for the production and living heat supply of the oxygen process nearby, the energy utilization efficiency can be improved, and the enterprise cost can be reduced; meanwhile, the method is also beneficial to reducing the coal burning quantity and reducing the pollution of the coal to the environment.
At present, a plurality of researches and applications are developed aiming at the recovery and utilization of the waste heat of an air compressor in an oxygen production process. Through searching for new, some related patents are searched, for example, patent CN106762557A discloses an intelligent hot water supply device based on air compressor waste heat recovery; according to the invention, intelligent hot water supply is realized by adding the cache heat storage equipment between the heat exchanger and a hot user. Although the method realizes the stability of the heat supply system, the heat loss of the system is larger due to excessive intermediate heat exchange and heat storage equipment. Patent CN108150422A discloses an air compressor waste heat recycling system, which drives a lithium bromide absorption type water chilling unit to produce cold water in a hot water manner by recycling air compressor waste heat; however, the hot water (generally at about 70-75 ℃) after driving the lithium bromide absorption type water chilling unit is not utilized, so that the energy utilization rate is low. Patent CN107178934A discloses an air compressor waste heat deep recycling system, in which three-stage compression of the air compressor is performed by three-stage heat exchange, and high-temperature water after heat exchange enters a waste heat extraction device and is converted into high-temperature waste heat water after heat exchange again, and the high-temperature waste heat water enters the waste heat deep recycling system; the system does not solve the problems that the air temperature is lower after the primary compression of the air compressor and the waste heat cannot be effectively utilized after being recovered.
In summary, the system and the method for utilizing the waste heat of the oxygen production process have some problems. The system and the method mainly reflect that the existing system and method for utilizing the waste heat of the air compressor in the oxygen production process do not consider that the temperature of air is low after the primary compression of the air compressor is actually operated, and the air cannot be effectively utilized after the waste heat is recovered; meanwhile, no solution is provided for how to effectively adapt to the fluctuation of the demand of the heat user for the waste heat recovery of the air compressor. And the waste heat resources of the oxygen production process are mainly used for domestic heat supply after being recovered, and the domestic heat supply is usually limited by heat supply quantity and heat supply radius, so that a large amount of waste heat resources of the oxygen production process cannot be fully utilized. Therefore, it is very necessary to search for a more practical and effective system and method for cascade utilization of the waste heat of the oxygen generation process, so that the waste heat of the oxygen generation process can be fully used for production and living heat supply of the oxygen process nearby.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a waste heat gradient utilization system and method for an oxygen production process. The waste heat of the oxygen production process can be used for production and living heat supply of the oxygen process in a gradient manner, and the waste heat of the air compressor is utilized to effectively adapt to the demand fluctuation of a heat user.
In order to achieve the purpose, the invention adopts the following technical scheme:
the cascade utilization system for the waste heat in the oxygen production process comprises an air compressor, a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, an oxygen generator, a refrigeration user, a heating user, a heat pump unit, a cooling tower, a water supply tank, a high-temperature water storage tank, a low-temperature liquid heat exchanger, a flow meter and various valves connected among the devices. The refrigeration user is a warm water type lithium bromide refrigeration unit and a user needing refrigeration capacity in production and life in the oxygen generation process.
Wherein air compressor machine one-level compression export and one-level heat exchanger gas side entry linkage, one-level heat exchanger gas side export and air compressor machine second grade compression entry linkage, air compressor machine second grade compression export and second grade heat exchanger gas side entry linkage, second grade heat exchanger gas side export and air compressor machine tertiary compression entry linkage, air compressor machine tertiary compression export and tertiary heat exchanger gas side entry linkage, tertiary heat exchanger gas side export and oxygenerator entry linkage.
The water side outlet of the primary heat exchanger is connected with the inlet of the heat pump unit through a switch regulating valve and is connected with the inlet of a heating user through a switch valve in a parallel mode; the water side outlet of the second-stage heat exchanger and the water side outlet of the third-stage heat exchanger are connected with a refrigerating user inlet through a switch valve; the refrigerating user outlet is connected with the high-temperature water storage tank inlet and the heating user inlet in parallel through the switch valve respectively; the outlet of the heat pump unit is connected with the inlet of the high-temperature water storage tank through a switch valve; the outlet of the high-temperature water storage tank is connected with the inlet of the low-temperature liquid heat exchanger and the inlet of a heating user respectively through a switch valve in a parallel mode; and the outlet of the heating user is connected with the inlet of the cooling tower through a switch valve.
The outlet of the low-temperature liquid heat exchanger is connected with the heat source inlet and the cooling tower inlet of the heat pump unit through a switch regulating valve and a switch valve respectively in parallel; the outlet of the cooling tower is converged with the heat source outlet and the water supply pool outlet driven by the heat pump unit through a switch valve, and is connected with the inlet of the water supply pool in a parallel mode; the convergence point is connected with the inlet of a flowmeter, the outlet of the flowmeter is respectively connected with the inlets of the water side of the first-stage heat exchanger, the second-stage heat exchanger and the third-stage heat exchanger, and the feedback signal of the flowmeter is connected with the switch regulating valve of the outlet of the water supply tank.
The cascade utilization method of the waste heat in the oxygen production process comprises two operation models, namely a non-operation mode of a low-temperature heat exchanger; and the second is the operation mode of the low-temperature heat exchanger.
Firstly, a non-operation mode of the low-temperature heat exchanger:
the normal temperature and normal pressure air is subjected to primary compression by an air compressor, the temperature reaches 75-95 ℃, the air enters a primary heat exchanger to exchange heat with cooling water at the temperature of 30-35 ℃, the temperature of the compressed air after heat exchange is 35-40 ℃, the air enters the air compressor for secondary compression and the air compressor for tertiary compression, the temperature of the secondary compressed air and the temperature of the tertiary compressed air can reach 100-120 ℃, the air after compression enters a secondary heat exchanger and a tertiary heat exchanger to exchange heat, and finally the air after tertiary compression and cooling enters an oxygen generator.
The cooling water entering the primary heat exchanger is subjected to heat exchange, then the temperature of the cooling water is 50-60 ℃, and the cooling water enters an inlet of a heating user through a switch valve; after the cooling water entering the secondary heat exchanger and the tertiary heat exchanger is heated to 80-90 ℃ through heat exchange, the cooling water enters a refrigeration user through a switch valve to serve as a heat source to drive a lithium bromide refrigeration unit, and the cooling energy is generated to be required by the user. After the lithium bromide unit is driven to refrigerate, the temperature of the hot water is reduced to 70-75 ℃ and flows out of a refrigeration user, and the hot water completely enters the high-temperature water storage tank through the switch valve.
30-50% of hot water at 70-75 ℃ in the high-temperature water storage tank is converged with low-temperature water at 55-65 ℃ from the primary heat exchanger through a switch regulating valve to serve as hot water to enter a heating user, and 50-70% of hot water at 70-75 ℃ is left in the high-temperature water storage tank; after heat supply, the water temperature is reduced to 40-50 ℃ and flows out of a heating user, the water enters a cooling tower through a switch valve and is cooled to 30-35 ℃, and the water flows out of the switch valve and passes through a flowmeter to be reused as cooling water of an air compressor for recycling; 50% -70% of hot water is left in the high-temperature water storage tank, and the water supply tank needs to be supplemented with water in an equivalent amount through a switch regulating valve; in the above operation process, the heating user belongs to low-load operation.
1500Nm after 25-35 hours of system operation3～2000Nm3The water storage amount in the high-temperature water storage tank can meet the water amount required by the low-temperature liquid heat exchanger in one-time operation; at the moment, the refrigeration parameters of the lithium bromide unit are adjusted, the temperature of hot water after the lithium bromide unit is driven to refrigerate is reduced to 65-70 ℃, the hot water flows out of a refrigeration user, a switch valve connected with a high-temperature water storage tank is closed, and the hot water which flows out of the switch valve and flows out of a primary heat exchanger and is at the temperature of 55-65 ℃ is gathered to be used as hot water to enter a heating user; after the circulation operation, the amount of hot water supplied to the heating user reaches a stable state, and the normal operation is realizedLoad operation; and the water storage capacity in the high-temperature water storage tank can completely meet the water quantity required by the low-temperature liquid heat exchanger in one-time operation.
The temperature of the return water of a heating user is reduced to 40-50 ℃ and flows out, the return water enters a cooling tower through a switch valve and is cooled to 30-35 ℃, and the return water flows out of the switch valve and passes through a flowmeter to be reused as cooling water of an air compressor for recycling; and the flow meter detects the return water amount, and when the return water amount is less than 2-5% of the total amount, the return water amount is fed back to a switch regulating valve of the water supply tank for water supplement.
Secondly, operating modes of the low-temperature heat exchanger are as follows:
when a trip fault occurs in a certain oxygen generator in the oxygen generation process and the amount of produced oxygen cannot meet the requirements of downstream oxygen consumption users, the pressure of an oxygen pipe network is insufficient; the trip fault of the oxygen generator generally needs 15-20 hours to recover, in order to ensure the stable production of downstream oxygen consuming users, liquid oxygen stored in a liquid oxygen tank for later use needs to be heated into normal-temperature gas to be conveyed into an oxygen pipe network, namely the liquid oxygen is heated from 183 ℃ below zero to 20 ℃ through a low-temperature liquid heat exchanger and is sent into the pipe network; according to the oxygen amount lost due to the fault of the oxygen generator, the supplement amount required by the oxygen pipe network is 3-5 thousands of standards per hour, and the longest time is 15-20 hours. On the basis, the water storage capacity of the high-temperature water storage tank is designed to be 1500Nm3～2000Nm3And the water storage capacity can meet the water quantity required by the operation of the low-temperature liquid heat exchanger for one time.
Stopping heating the heating user in the operation mode of the low-temperature heat exchanger; water with the temperature of 70-75 ℃ in the high-temperature water storage tank enters a low-temperature liquid heat exchanger through a switch regulating valve at the flow rate of 180-300 t/h to heat low-temperature liquid oxygen, so that the water is heated to 20 ℃ and enters an oxygen pipe network, the water with the temperature of 70-75 ℃ is cooled to 45-55 ℃ after heat exchange and flows out of the low-temperature liquid heat exchanger, wherein 20-40% of the low-temperature water enters a heat pump unit through the switch regulating valve to serve as a driving heat source, is cooled to 30-35 ℃ after driving the heat pump unit, and flows out of a driving heat source outlet; 60-80% of low-temperature water enters the cooling tower through the switch valve to be cooled to 30-35 ℃.
The heat exchange water with the temperature of 50-60 ℃ from the primary heat exchanger enters a heat pump unit through a switch regulating valve to be heated to 70-75 ℃, and then flows out of the switch valve to enter a high-temperature water storage tank; compared with the non-operation mode of the low-temperature heat exchanger, the water inlet flow of the high-temperature water storage tank is increased by 50-80% in the operation mode of the low-temperature heat exchanger, and the water outlet flow is increased by 100-300%; the water outlet flow of the 1500Nm 3-2000 Nm3 high-temperature water storage tank can reach 180-300 t/h; after the operation is carried out for 15-20 hours, the oxygen generator is recovered to operate, and the water storage amount in the high-temperature water storage tank can be reduced to 5% of the full load amount to the maximum extent; after the oxygen generator recovers, the system is switched from the operation mode of the low-temperature heat exchanger to the non-operation mode of the low-temperature heat exchanger until the water amount in the high-temperature water storage tank is increased to full load for the next operation of the low-temperature heat exchanger.
Compared with the prior art, the invention has the beneficial effects that:
the cascade utilization of the waste heat of the air compressor is realized; the problem of unplanned, intermittent and instant heating quantity of low-temperature liquid oxygen heating is solved through the optimization design of the oxygen generation process waste heat cascade utilization system and method, and the waste heat of the oxygen generation process is effectively utilized in production and life. Meanwhile, the problem that the air temperature of the air compressor after primary compression is low and the air cannot be effectively utilized after waste heat recovery is carried out is solved, and the waste heat utilization efficiency of the system is improved. The method has the characteristics of saving energy, reducing maintenance cost and the like.
Drawings
FIG. 1 is a schematic diagram of the structure and process of the present invention.
In the figure:
1. the system comprises an air compressor primary compression device, an air compressor secondary compression device, an air compressor tertiary compression device, a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, a 7 oxygen generator, a 8 refrigeration user, a 9 heating user, a 10 heat pump unit, a 11 cooling tower, a 12 water supply tank, a 13 high-temperature water storage tank, a 14 low-temperature liquid heat exchanger, a 15, 16, 19, 21, 22, 23, 25, 28 and 29 switch valve, a 17, 18, 20, 24, 26 and 27 switch adjusting valve and a 30 flow meter.
Detailed Description
The invention discloses a cascade utilization system and method for waste heat in an oxygen production process. Those skilled in the art can modify the process parameters appropriately to achieve the desired results with reference to the disclosure herein. It is expressly intended that all such similar substitutes and modifications which would be obvious to one skilled in the art are deemed to be included in the invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and modifications in the methods and applications described herein, as well as other suitable variations and combinations, may be made to implement and use the techniques of this invention without departing from the spirit and scope of the invention.
The cascade utilization system for the waste heat in the oxygen production process comprises an air compressor primary compression 1, an air compressor secondary compression 2, an air compressor tertiary compression 3, a primary heat exchanger 4, a secondary heat exchanger 5, a tertiary heat exchanger 6, an oxygen generator 7, a refrigeration user 8, a heating user 9, a heat pump unit 10, a cooling tower 11, a water supply tank 12, a high-temperature water storage tank 13, a low-temperature liquid heat exchanger 14, a flow meter 30 and various valves connected among the devices. The refrigeration user 8 is a warm water type lithium bromide refrigeration unit and a user needing refrigeration capacity in production and life in an oxygen generation process.
1 export of air compressor machine one-level compression and 4 gas side entry linkage of one-level heat exchanger, 4 gas side exports and 2 entry linkage of air compressor machine second grade compression of one-level heat exchanger, 2 exports of air compressor machine second grade compression and 5 gas side entry linkage of second grade heat exchanger, 5 gas side exports and 3 entry linkage of air compressor machine tertiary compression, 3 exports of air compressor machine tertiary compression and 6 gas side entry linkage of tertiary heat exchanger, 6 gas side exports and 7 entry linkage of oxygenerator of tertiary heat exchanger.
The outlet of the water side of the primary heat exchanger 4 is connected with the inlet of the heat pump unit 10 through a switch regulating valve 18, and is connected with the inlet of the heating user 9 through a switch valve in a parallel mode; the water side outlets of the secondary heat exchanger 5 and the tertiary heat exchanger 6 are connected with the inlets of refrigeration users 8 through switch valves.
The outlet of the refrigeration user 8 is connected with the inlet of the high-temperature water storage tank 13 and the inlet of the heating user 9 in parallel through switch valves respectively; the outlet of the heat pump unit 10 is connected with the inlet of the high-temperature water storage tank 13 through a switch valve; the outlet of the high-temperature water storage tank 13 is also connected with the inlet of the low-temperature liquid heat exchanger 14 and the inlet of the heating user 9 in parallel through a switch regulating valve respectively;
the outlet of the heating user 9 is connected with the inlet of the cooling tower 11 through a switch valve; the outlet of the low-temperature liquid heat exchanger 14 is connected with the heat source inlet and the inlet of the cooling tower 11 driven by the heat pump unit 10 through a switch regulating valve 20 and a switch valve respectively in parallel;
the outlet of the cooling tower 11 is converged with the outlet of the heat source and the outlet of the water supply pool driven by the heat pump unit 10 through a switch valve, and is connected with the inlet of the water supply pool 12 in a parallel mode; the convergence point is connected with the inlet of a flowmeter 30, the outlet of the flowmeter 30 is respectively connected with the water side inlets of the first-stage heat exchanger 4, the second-stage heat exchanger 5 and the third-stage heat exchanger 6, and the feedback signal of the flowmeter 30 is connected with the outlet switch regulating valve 24 of the water supply pool 12.
Example 1:
non-operation mode of the low-temperature heat exchanger:
in the non-operation mode of the low-temperature heat exchanger, the switching valves 15, 16, 22, 23 and 25 are in an opening state, and the switching valves 19, 21, 28 and 29 are in a closing state; the on-off regulating valves 17, 24 are in an open state, and the on-off regulating valves 18, 20, 26, 27 are in a closed state. The maximum designed water storage capacity of the high-temperature water storage tank 13 is 1800m3。
15 ten thousand Nm3The temperature of normal temperature and pressure air reaches 95 ℃ after the air passes through the first-stage compression 1 of the air compressor, the air enters the first-stage heat exchanger 4 to exchange heat with cooling water at the temperature of 35 ℃, the temperature of the compressed air after heat exchange is 40 ℃ and enters the second-stage compression of the air compressor and the third-stage compression of the air compressor, the temperature of the second-stage compressed air and the temperature of the third-stage compressed air can reach 120 ℃, the air after compression enters the second-stage heat exchanger 5 and the third-stage heat exchanger 6 to exchange heat, and finally the.
The temperature of cooling water entering the primary heat exchanger 4 is 60 ℃ after heat exchange, and the cooling water enters the inlet of a heat supply user 9 through a switch valve 25; cooling water entering the secondary heat exchanger 5 and the tertiary heat exchanger 6 is about 48t/h respectively, and is heated to 90 ℃ through heat exchange; hot water with the temperature of 90 ℃ at about 96t/h enters a refrigeration user 8 through a switch valve 15 to be used as a heat source to drive a lithium bromide refrigeration unit, and cold energy is generated to be required by the user. After the lithium bromide unit is driven to refrigerate, the temperature of hot water is reduced to 75 ℃ and flows out of a refrigeration user, and 75 ℃ water of about 96t/h enters the high-temperature water storage tank 13 through the switch valve 16.
Then 75 ℃ water in the high-temperature water storage tank 13 flows out 36t/h through the switch regulating valve 17 and is converged into 108t/h hot water at 65 ℃ with the temperature of 60t/h and low-temperature hot water from the primary heat exchanger 4, and the hot water enters the heat supply user 9, and the residual 60t/h water at 75 ℃ is left in the high-temperature water storage tank 13; after heat supply, the water temperature is reduced to 45 ℃ and flows out of a heat supply user 9, enters a cooling tower 11 through a switch valve 22 to be reduced to 35 ℃, flows out of a switch valve 23 and is reused as cooling water of the air compressor through a flowmeter 30.
Since 60t/h of water with 75 ℃ is left in the high-temperature water storage tank 13, the water supply tank 12 needs to be supplemented with equal amount of water through the switch regulating valve 24. After the system operates for 30 hours, the water storage amount in the high-temperature water storage tank 13 reaches 1800m3This water storage capacity can satisfy the water amount required for the operation of the low-temperature liquid heat exchanger 14 for one time; at the moment, the refrigeration parameters of the lithium bromide unit are adjusted, the temperature of hot water is reduced to 70 ℃ and flows out of a refrigeration user, meanwhile, the switch valve 16 is closed, and the switch valve 29 is opened; 96t/h of low-temperature hot water with the temperature of 60 ℃ flows out of the primary heat exchanger 4 through the switch regulating valve 29, and is converged into 168t/h of 65.7 ℃ hot water to enter a heat supply user 9.
After one circulation stable operation, the hot water quantity supplied to the heat supply user 9 reaches 168t/h, and the water storage quantity in the high-temperature water storage tank 13 reaches 1800m3, so that the requirement of one-time low-temperature liquid heat exchange can be completely met. The temperature of the return water of the heat supply user 9 is reduced to 45 ℃ and flows out, the return water enters the cooling tower 11 through the switch valve 22 and is cooled to 35 ℃, and the return water flows out of the switch valve 23 and passes through the flowmeter 30 to be reused as cooling water of the air compressor for recycling; the flow meter 30 detects the amount of return water, and when the amount of return water is less than 4% of the total amount, the return water is fed back to the switch regulating valve 24 for water supplement.
Example 2:
the operation mode of the low-temperature heat exchanger is as follows:
in the low-temperature heat exchanger operation mode, the switching valves 15, 16, 19, 21, 23, 28 are in an open state, and the switching valves 22, 25, 29 are in a closed state; the on-off regulating valves 18, 20, 24, 26, 27 are in an open state, and the on-off regulating valve 17 is in a closed state. The maximum designed water storage capacity of the high-temperature water storage tank 13 is 1800m3。
15 ten thousand Nm3The temperature of normal temperature and pressure air reaches 95 ℃ after the air passes through the first-stage compression 1 of the air compressor, the air enters the first-stage heat exchanger 4 to exchange heat with cooling water at the temperature of 35 ℃, the temperature of the compressed air after heat exchange is 40 ℃ and enters the second-stage compression of the air compressor and the third-stage compression of the air compressor, the temperature of the second-stage compressed air and the temperature of the third-stage compressed air can reach 120 ℃, the air after compression enters the second-stage heat exchanger 5 and the third-stage heat exchanger 6 to exchange heat, and finally the.
The temperature of cooling water entering the primary heat exchanger 4 is 60 ℃ after heat exchange, and the cooling water enters the inlet of a heat supply user 9 through a switch valve 25; cooling water entering the secondary heat exchanger 5 and the tertiary heat exchanger 6 is about 48t/h respectively, and is heated to 90 ℃ through heat exchange; hot water with the temperature of 90 ℃ at about 96t/h enters a refrigeration user 8 through a switch valve 15 to be used as a heat source to drive a lithium bromide refrigeration unit, and cold energy is generated to be required by the user. After the lithium bromide unit is driven to refrigerate, the temperature of hot water is reduced to 70 ℃ and flows out of a refrigeration user, about 96t/h of hot water flows out of the lithium bromide unit through a switch adjusting valve 29, and the hot water with the temperature of 65.7 ℃ and the temperature of 168t/h of low-temperature hot water flowing out of the primary heat exchanger 4 is converged into hot water with the temperature of 65.7 ℃ and enters a heat supply user 9.
When a certain oxygen generator has a trip and the pressure of an oxygen pipe network is insufficient, the maximum oxygen supplement amount is 4.5 kilomega per hour, and the maximum oxygen supplement amount lasts for 20 hours; during the period, liquid oxygen needs to be heated by a low-temperature liquid heat exchanger to raise the temperature from minus 183 ℃ to 20 ℃, and the required water amount at 75 ℃ is 250 t/h. And under the operation mode of the low-temperature heat exchanger, the refrigeration parameters of the lithium bromide unit are adjusted, the temperature of hot water is reduced to 75 ℃ and flows out of a refrigeration user, meanwhile, the switch valve 29 is closed, and the switch valve 16 is opened, so that 96t/h of water at 75 ℃ enters the high-temperature water storage tank 13.
75 ℃ water in the high-temperature water storage tank 13 enters the low-temperature liquid heat exchanger 14 through the switch regulating valve 26 at a flow rate of 250t/h to heat low-temperature liquid oxygen, so that the temperature of the low-temperature liquid oxygen is raised to 20 ℃ and enters an oxygen pipe network, the 250t/h 75 ℃ water is cooled to 50 ℃ after heat exchange and flows out of the low-temperature liquid heat exchanger 14, wherein 55t/h of low-temperature water enters the heat pump unit 10 through the switch regulating valve 20 to serve as a driving heat source, the temperature of the low-temperature water is reduced to 35 ℃ after the heat pump unit 10 is driven, and the; the rest 195t/h of low-temperature water enters the cooling tower 11 through the on-off switch 28 to be cooled to 35 ℃.
Meanwhile, the switch valves 17 and 25 are controlled to be closed, and the high-temperature water storage tank 13 stops supplying heat to the heat supply user 9; the heat exchange water with the temperature of about 72t/h and the temperature of 60 ℃ from the primary heat exchanger 4 enters the heat pump unit 10 through the switch regulating valve 18 to be heated to 75 ℃, and then flows out of the switch valve 19 to enter the high-temperature water storage tank 13; at the moment, the water inlet flow of the high-temperature water storage tank 13 is 168t/h, the water outlet flow is 250t/h, the oxygen generator is recovered to operate after the operation for 20 hours, and the water storage amount in the high-temperature water storage tank 14 is reduced from 1800m3 to 160m 3. Meanwhile, the system is switched from the low-temperature heat exchanger operation mode to the low-temperature heat exchanger non-operation mode until the water quantity in the high-temperature water storage tank 14 is increased to 1800m3 for the next low-temperature heat exchanger operation.
The cascade utilization of the waste heat of the air compressor is realized; and the problems of unplanned, intermittent and instant heating of low-temperature liquid oxygen heating are solved through the design of the high-temperature water storage tank, and the effective utilization of the waste heat of the oxygen production process in production and life is realized. Meanwhile, the problem that the air temperature of the air compressor after primary compression is low and the air cannot be effectively utilized after waste heat recovery is carried out is solved, and the waste heat utilization efficiency of the system is improved. The method has the characteristics of saving energy, reducing maintenance cost and the like.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (2)
1. The cascade utilization system for the waste heat in the oxygen production process is characterized by comprising an air compressor primary compression device, an air compressor secondary compression device, an air compressor tertiary compression device, a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, an oxygen generator, a refrigeration user, a heating user, a heat pump unit, a cooling tower, a water supply tank, a high-temperature water storage tank, a low-temperature liquid heat exchanger, a flow meter and a valve; the refrigeration users are warm water type lithium bromide refrigeration units and users needing refrigeration capacity in production and life in the oxygen generation process;
the primary compression of the air compressor, the air side of the primary heat exchanger, the secondary compression of the air compressor, the air side of the secondary heat exchanger, the tertiary compression of the air compressor, the air side of the tertiary heat exchanger and the oxygen generator are connected in series;
the water side outlet of the primary heat exchanger is connected with the inlet of the heat pump unit and is connected with the inlet of a heating user in a parallel mode; the water side outlet of the second-stage heat exchanger and the water side outlet of the third-stage heat exchanger are connected with a refrigerating user inlet;
the refrigerating user outlet is respectively connected with the high-temperature water storage tank inlet and the heating user inlet in a parallel mode; the outlet of the heat pump unit is connected with the inlet of the high-temperature water storage tank; the outlet of the high-temperature water storage tank is also connected with the inlet of the low-temperature liquid heat exchanger and the inlet of a heating user in parallel;
the outlet of the heating user is connected with the inlet of the cooling tower through a switch valve; the outlet of the low-temperature liquid heat exchanger is respectively connected with the heat source inlet and the cooling tower inlet of the heat pump unit in a parallel connection manner;
the outlet of the cooling tower is converged with the outlet of the heat source driven by the heat pump unit and the outlet of the water supply pool, and is connected with the inlet of the water supply pool in a parallel mode; the convergence point is connected with the inlet of a flowmeter, the outlet of the flowmeter is respectively connected with the inlets of the water side of the first-stage heat exchanger, the second-stage heat exchanger and the third-stage heat exchanger, and the feedback signal of the flowmeter is connected with the switch regulating valve of the outlet of the water supply tank.
2. The cascade utilization method for the waste heat of the oxygen generation process based on the system of claim 1 is characterized by comprising two operation models, namely a non-operation mode of the low-temperature heat exchanger and an operation mode of the low-temperature heat exchanger;
1) non-operation mode of the low-temperature heat exchanger:
the normal temperature and pressure air is subjected to primary compression by an air compressor, the temperature reaches 75-95 ℃, the air enters a primary heat exchanger to exchange heat with cooling water, the compressed air after heat exchange and cooling enters a secondary compression of the air compressor and a tertiary compression of the air compressor, the temperature of the secondary compressed air and the temperature of the tertiary compressed air are 100-120 ℃, the compressed air enters the secondary heat exchanger and the tertiary heat exchanger to exchange heat after compression, and finally the air after the tertiary compression and cooling enters an oxygen generator;
the cooling water entering the primary heat exchanger is subjected to heat exchange, then the temperature of the cooling water is 50-60 ℃, and the cooling water enters an inlet of a heat supply user; after the cooling water entering the secondary heat exchanger and the tertiary heat exchanger is heated to 80-90 ℃ through heat exchange, the cooling water enters a refrigeration user to serve as a heat source to drive a lithium bromide refrigeration unit, and cold energy is generated to be required by the user; after the lithium bromide unit is driven to refrigerate, the temperature of hot water is reduced to 70-75 ℃, the hot water flows out of a refrigeration user and completely enters a high-temperature water storage tank;
30% -50% of hot water in the high-temperature water storage tank and low-temperature water with the temperature of 55-65 ℃ from the primary heat exchanger are converged to be used as hot water to enter a heat supply user, and 50% -70% of the hot water is left in the high-temperature water storage tank; after heat supply, the water temperature is reduced to 40-50 ℃, flows out of a heat supply user, enters a cooling tower, and is cooled to 30-35 ℃ for recycling; 50% -70% of hot water is left in the high-temperature water storage tank, and the water supply tank needs to be supplemented with water in an equivalent amount; in the operation process, the heating user belongs to low-load operation;
1500Nm after 25-35 hours of system operation3～2000Nm3The water storage amount in the high-temperature water storage tank can meet the water amount required by the low-temperature liquid heat exchanger in one-time operation; at the moment, the refrigeration parameters of the lithium bromide unit are adjusted, the temperature of hot water after the lithium bromide unit is driven to refrigerate is reduced to 65-70 ℃, the hot water flows out of a refrigeration user, a switch valve connected with a high-temperature water storage tank is closed, and the hot water which flows out of the switch valve and flows out of a primary heat exchanger and is at the temperature of 55-65 ℃ is gathered to serve as hot water to enter a heat supply user;
the temperature of the return water of the heat supply user is reduced to 40-50 ℃, the return water flows out, and the return water enters a cooling tower to be cooled to 30-35 ℃ for recycling; the flow meter detects the amount of return water, and when the amount of return water is lower than 2-5% of the total amount, the return water is fed back to a switch regulating valve of the water supply tank for water supplement;
2) the operation mode of the low-temperature heat exchanger is as follows:
stopping heating the heating user in the operation mode of the low-temperature heat exchanger; water with the temperature of 70-75 ℃ in the high-temperature water storage tank enters a low-temperature liquid heat exchanger at the flow rate of 180-300 t/h to heat low-temperature liquid oxygen, the water is heated to 20 ℃ and enters an oxygen pipe network, the water with the temperature of 70-75 ℃ is cooled to 45-55 ℃ after heat exchange and flows out of the low-temperature liquid heat exchanger, wherein 20-40% of the low-temperature water enters a heat pump unit as a driving heat source, and is cooled to 30-35 ℃ after the heat pump unit is driven, and flows out of a driving heat source outlet; 60 to 80 percent of low-temperature water enters a cooling tower to be cooled to 30 to 35 ℃;
the heat exchange water with the temperature of 50-60 ℃ from the primary heat exchanger enters a heat pump unit to be heated to 70-75 ℃, and then flows out to enter a high-temperature water storage tank; after the operation is carried out for 15-20 hours, the oxygen generator recovers, the system is switched from the operation mode of the low-temperature heat exchanger to the non-operation mode of the low-temperature heat exchanger until the water amount in the high-temperature water storage tank is increased to full load, so that the next operation of the low-temperature heat exchanger is required.
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