Multistage utilization system and method for waste heat of air compressor
阅读说明：本技术 一种空压机余热多级利用系统及方法 (Multistage utilization system and method for waste heat of air compressor ) 是由 徐伟 倪健勇 马光宇 王声 张天赋 陈鹏 刘芳 高军 王飞 王永 于 2019-10-30 设计创作，主要内容包括：本发明涉及一种空压机余热多级利用系统,包括空压机一级压缩、空压机二级压缩、空压机三级压缩、一级换热器、二级换热器、三级换热器、制氧机、制冷用户、供热用户、热泵机组、冷却塔、补水泵、流量计；本发明通过对空压机三级压缩空气余热回收方案的设计,提出了一种空压机余热多级利用系统及方法,能够对空压机冷却水余热进行直接利用,减少了中间换热设备,避免了系统的过多散热损失,提高了系统的热效率；并通过部分回水驱动热泵方式加热一级换热器出水的方法,对空压机余热进行了多级有效利用,解决了空压机一级压缩后气体温度偏低进行余热回收后无法有效利用的问题,提高了系统的余热利用效率。具有节约能源、降低维护成本等特点。(The invention relates to a multistage utilization system for waste heat of an air compressor, which comprises primary compression of the air compressor, secondary compression of the air compressor, tertiary compression of the air compressor, a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, an oxygen generator, a refrigeration user, a heat supply user, a heat pump unit, a cooling tower, a water replenishing pump and a flow meter, wherein the primary compression of the air compressor is performed by the primary compression of the air compressor; the invention provides the multistage utilization system and the multistage utilization method for the waste heat of the air compressor through the design of the scheme for recovering the waste heat of the three-stage compressed air of the air compressor, so that the waste heat of the cooling water of the air compressor can be directly utilized, intermediate heat exchange equipment is reduced, excessive heat dissipation loss of the system is avoided, and the heat efficiency of the system is improved; and the method for heating the water discharged from the primary heat exchanger in a manner of driving the heat pump by partial backwater effectively utilizes the waste heat of the air compressor in multiple stages, solves the problem that the waste heat cannot be effectively utilized after the gas temperature is low after the primary compression of the air compressor and the waste heat recovery, and improves the waste heat utilization efficiency of the system. The method has the characteristics of saving energy, reducing maintenance cost and the like.)
1. A multi-stage utilization system for waste heat of an air compressor is characterized by comprising a primary compression of the air compressor, a secondary compression of the air compressor, a tertiary compression of the air compressor, a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, an oxygen generator, a refrigeration user, a heat supply user, a heat pump unit, a cooling tower, a water replenishing pump and a flowmeter;
the primary compression outlet of the air compressor is connected with the gas side inlet of the primary heat exchanger, the gas side outlet of the primary heat exchanger is connected with the secondary compression inlet of the air compressor, the secondary compression outlet of the air compressor is connected with the gas side inlet of the secondary heat exchanger, the gas side outlet of the secondary heat exchanger is connected with the tertiary compression inlet of the air compressor, the tertiary compression outlet of the air compressor is connected with the gas side inlet of the tertiary heat exchanger, and the gas side outlet of the tertiary heat exchanger is connected with the inlet of the; the water side outlet of the primary heat exchanger is connected with the inlet of the heat pump unit and is respectively connected with the inlet of the water bath type gasifier and the inlet of the heat supply user in a parallel mode; the outlet of the heat pump unit is connected with the water side outlets of the two-stage heat exchanger and the three-stage heat exchanger which are intersected, and is respectively connected with the inlet of a refrigeration user and the inlet of the water bath type gasifier in a parallel connection mode; the outlet of the refrigeration user is connected with the inlet of the water bath type gasifier; the outlet of the water bath type gasifier is connected with the inlet of a heat supply user and is connected with the outlet of the heat supply user in a parallel mode; the heat supply user outlet is respectively connected with the heat pump unit driving heat source inlet and the cooling tower inlet in a parallel connection mode; the heat pump set drives the heat source outlet and the cooling tower outlet and the outlet of the water replenishing pump to be connected in an intersecting manner, then the heat pump set is connected with the inlet of the flow meter, the outlet of the flow meter 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 flow meter is transmitted to the water replenishing pump.
2. The waste heat recovery method of the air compressor waste heat multistage utilization system according to claim 1, characterized by comprising the following steps:
summer refrigeration mode
In a summer refrigeration operation mode, normal temperature and pressure air is subjected to primary compression by an air compressor to reach 75-95 ℃, enters a primary heat exchanger to exchange heat with cooling water at 30-35 ℃, enters a secondary compression air compressor and a tertiary compression air compressor to reach 100-120 ℃ after the temperature of the compressed air after heat exchange is 35-40 ℃, enters the secondary heat exchanger and the tertiary heat exchanger to exchange heat, and finally enters an oxygen generator after the air subjected to the tertiary compression and cooling;
the cooling water entering the primary heat exchanger is subjected to heat exchange, then the temperature of the cooling water is 65-75 ℃, and the cooling water enters a heat pump unit through a switch valve; the cooling water entering the secondary heat exchanger and the tertiary heat exchanger is heated to 80-90 ℃ through heat exchange; the refrigerant enters a refrigeration user through a switch valve to serve as a heat source to drive a refrigeration unit, and the cold energy is generated to be required by the refrigeration user; after the refrigeration of a driving refrigerating unit, the temperature of hot water is reduced to 70-75 ℃ and flows out of a refrigeration user, the hot water enters a water bath type gasifier to heat a low-temperature air source of an oxygen production process, the temperature is reduced to 45-55 ℃ after heat exchange and flows out, the hot water enters a heat pump unit to serve as a driving heat source of the heat pump unit, water at 65-75 ℃ from a primary heat exchanger is heated to 80-90 ℃, the water is mixed with water at 80-90 ℃ from a secondary heat exchanger and a tertiary heat exchanger and enters the refrigeration user to drive the refrigerating unit, the temperature is reduced to 30-35 ℃ after the low-temperature hot water at 45-55 ℃ drives the heat pump unit, and the water flows out from a heat source outlet;
after the hot water drives the refrigerating unit to refrigerate, the hot water enters a water bath type gasifier to heat a low-temperature gas source, the temperature is reduced to 45-55 ℃ after heat exchange, the low-temperature gas source flows out, a part of return water is controlled to enter the heat pump unit as a driving heat source, and the 65-75 ℃ water from the primary heat exchanger is continuously heated to 80-90 ℃ and is supplied to a refrigerating user for use; the temperature of the part of return water is reduced to 30-35 ℃ after the part of return water drives the heat pump unit, the part of return water flows out and is converged with the rest of return water flowing through the cooling tower and cooled to 30-35 ℃, the part of return water is used as cooling water of the air compressor again for recycling, the return water amount is detected through a flowmeter, and when the return water amount is lower than the total circulation amount by 2-5%, the return water amount is fed back to the water replenishing pump for replenishing.
3. The waste heat recovery method of the air compressor waste heat multistage utilization system according to claim 1, characterized by comprising the following steps:
winter heating mode
In a winter heating operation mode, normal temperature and pressure air is subjected to primary compression by an air compressor to reach 75-95 ℃, enters a primary heat exchanger to exchange heat with cooling water at 30-35 ℃, enters a secondary compression air compressor and a tertiary compression air compressor to reach 100-120 ℃ after heat exchange, enters the secondary heat exchanger and the tertiary heat exchanger to exchange heat after compression, and finally enters an oxygen generator after tertiary compression and cooling;
the temperature of the cooling water entering the primary heat exchanger is 65-75 ℃ after heat exchange; the cooling water entering the second-stage heat exchanger and the third-stage heat exchanger is heated to 80-90 ℃ after heat exchange, enters a water bath type gasifier to heat a low-temperature air source of an oxygen production process, the temperature is reduced to 60-70 ℃ after heat exchange, the low-temperature air source flows out, is mixed with the effluent water of 65-75 ℃ after heat exchange with the first-stage heat exchanger, the mixed hot water enters a heat supply user, and the water temperature is reduced to 40-50 ℃ after heat supply; wherein, part of the return water enters a heat pump unit as a driving heat source, the water with the temperature of 65-75 ℃ from the primary heat exchanger is heated to 80-90 ℃ and is supplied to a water bath type gasifier for use, and the rest of the low-temperature water enters a cooling tower to be cooled to 30-35 ℃ and is reused as cooling water of an air compressor; the system detects the return water amount through a flowmeter, and when the return water amount is lower than the circulation total amount by 2-5%, the return water amount is fed back to a water replenishing pump for water replenishing.
4. The waste heat recovery method of the air compressor waste heat multistage utilization system according to claim 1, characterized by comprising the following steps:
spring and autumn non-refrigeration and non-heating mode
Under a spring and autumn non-refrigeration non-heating operation mode, normal temperature and normal pressure air is subjected to primary compression by an air compressor, then the temperature of the air reaches 75-95 ℃, the air enters a primary heat exchanger to exchange heat with cooling water at 30-35 ℃, the temperature of the compressed air after heat exchange is 35-40 ℃, the air enters the air compressor to be subjected to secondary compression and tertiary compression by the air compressor, 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;
cooling water entering a primary heat exchanger is subjected to heat exchange, and the temperature is 65-75 ℃; the cooling water entering the secondary heat exchanger and the tertiary heat exchanger is heated to about 80-90 ℃ through heat exchange, the 80-90 ℃ outlet water of the secondary heat exchanger and the tertiary heat exchanger is mixed with the 65-75 ℃ outlet water of the primary heat exchanger, the mixed hot water with the temperature of 75-85 ℃ enters a water bath type gasifier to heat a low-temperature air source, and the temperature is reduced to 45-60 ℃ after heat exchange; then the mixture enters a cooling tower to be cooled to 30-35 ℃, and then flows out to be used as cooling water of an air compressor again for recycling; and the flow meter detects the return water amount, and when the return water amount is lower than 2-5% of the total amount, the return water amount is fed back to the water replenishing pump for water replenishing.
Technical Field
The invention relates to the technical field of energy conservation in the steel industry, in particular to a multistage utilization system and method for waste heat of an air compressor
Background
The large-scale iron and steel enterprises are provided with an oxygen generation process, energy media such as liquid oxygen, liquid nitrogen, liquid helium and the like can be produced in the process, the liquid oxygen, the liquid nitrogen, the liquid helium and the like need to be heated and gasified when corresponding energy media are needed in production, and the gas energy media are conveyed to users through a pipe network. At present, most of domestic oxygen production processes adopt a water bath type gasifier to heat a low-temperature energy medium, a heating heat source is generally steam, and a large amount of high-quality energy can be consumed by the heating mode, so that the production cost of enterprises is increased. Meanwhile, 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 production and living heat supply of an oxygen production 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 the air compressor in China.
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 air compressor waste heat utilization system and method have some problems. The waste heat utilization system and the method mainly reflect that the heat loss of the system is large due to excessive intermediate heat exchange equipment in the conventional air compressor waste heat utilization system and method; and the problems that the temperature of air is lower after the primary compression of the air compressor in actual operation, the waste heat cannot be effectively utilized after being recovered and the like are not considered. Therefore, it is very necessary to find a more practical and effective system and method for utilizing the waste heat of the air compressor.
Disclosure of Invention
The invention aims to solve the technical problem of providing a multi-stage utilization system and a method for waste heat of an air compressor, wherein the intermediate heat exchange equipment is reduced by directly utilizing the waste heat of cooling water of the air compressor in multiple stages, so that excessive heat loss of the system is avoided; and the water outlet of the primary heat exchanger is heated in a mode of driving the heat pump by partial backwater, so that the waste heat utilization efficiency of the system is improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
a multi-stage utilization system for waste heat of an air compressor comprises primary compression of the air compressor, secondary compression of the air compressor, tertiary compression of the air compressor, a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, an oxygen generator, a refrigeration user, a heat supply user, a heat pump unit, a cooling tower, a water replenishing pump and a flow meter;
the primary compression outlet of the air compressor is connected with the gas side inlet of the primary heat exchanger, the gas side outlet of the primary heat exchanger is connected with the secondary compression inlet of the air compressor, the secondary compression outlet of the air compressor is connected with the gas side inlet of the secondary heat exchanger, the gas side outlet of the secondary heat exchanger is connected with the tertiary compression inlet of the air compressor, the tertiary compression outlet of the air compressor is connected with the gas side inlet of the tertiary heat exchanger, and the gas side outlet of the tertiary heat exchanger is connected with the inlet of the; the water side outlet of the primary heat exchanger is connected with the inlet of the heat pump unit and is respectively connected with the inlet of the water bath type gasifier and the inlet of the heat supply user in a parallel mode; the outlet of the heat pump unit is connected with the water side outlets of the two-stage heat exchanger and the three-stage heat exchanger which are intersected, and is respectively connected with the inlet of a refrigeration user and the inlet of the water bath type gasifier in a parallel connection mode; the outlet of the refrigeration user is connected with the inlet of the water bath type gasifier; the outlet of the water bath type gasifier is connected with the inlet of a heat supply user and is connected with the outlet of the heat supply user in a parallel mode; the heat supply user outlet is respectively connected with the heat pump unit driving heat source inlet and the cooling tower inlet in a parallel connection mode; the heat pump set drives the heat source outlet and the cooling tower outlet and the outlet of the water replenishing pump to be connected in an intersecting manner, then the heat pump set is connected with the inlet of the flow meter, the outlet of the flow meter 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 flow meter is transmitted to the water replenishing pump.
The refrigeration user is refrigerated by a lithium bromide unit.
The waste heat recovery method of the system comprises a summer refrigeration mode, a winter heating mode and a spring and autumn non-refrigeration non-heating mode, and specifically comprises the following steps:
summer cooling mode
In a summer refrigeration operation mode, normal temperature and pressure air is subjected to primary compression by an air compressor to reach 75-95 ℃, enters a primary heat exchanger to exchange heat with cooling water at 30-35 ℃, enters a secondary compression air compressor and a tertiary compression air compressor to reach 100-120 ℃ after the temperature of the compressed air after heat exchange is 35-40 ℃, enters the secondary heat exchanger and the tertiary heat exchanger to exchange heat, and finally enters an oxygen generator after the air subjected to the tertiary compression and cooling;
the cooling water entering the primary heat exchanger is subjected to heat exchange, then the temperature of the cooling water is 65-75 ℃, and the cooling water enters a heat pump unit through a switch valve; the cooling water entering the secondary heat exchanger and the tertiary heat exchanger is heated to 80-90 ℃ through heat exchange; the refrigerant enters a refrigeration user through a switch valve to be used as a heat source to drive a lithium bromide refrigeration unit, and the cold energy is generated to be required by the refrigeration user; after a lithium bromide unit is driven to refrigerate, the temperature of hot water is reduced to 70-75 ℃ and flows out of a refrigeration user, the hot water enters a water bath type gasifier to heat a low-temperature air source of an oxygen generation process, the temperature is reduced to 45-55 ℃ after heat exchange and flows out, the hot water enters a heat pump unit to serve as a driving heat source of the heat pump unit, water at 65-75 ℃ from a primary heat exchanger is heated to 80-90 ℃, the water is mixed with water at 80-90 ℃ from a secondary heat exchanger and a tertiary heat exchanger and enters the refrigeration user to drive the lithium bromide unit, the temperature is reduced to 30-35 ℃ after the low-temperature hot water at 45-55 ℃ drives the heat pump unit, and the low-temperature hot water flows;
after the hot water drives the lithium bromide unit to refrigerate, the lithium bromide unit enters a water bath type gasifier to heat a low-temperature air source, the temperature is reduced to 45-55 ℃ after heat exchange, the low-temperature air source flows out, a part of return water is controlled to enter the heat pump unit as a driving heat source, and 65-75 ℃ water from the primary heat exchanger is continuously heated to 80-90 ℃ and is supplied to a refrigeration user for use; the temperature of the part of return water is reduced to 30-35 ℃ after the part of return water drives the heat pump unit, the part of return water flows out and is converged with the rest of return water which flows through the cooling tower and is cooled to 30-35 ℃, the part of return water is used as cooling water of the air compressor again for recycling, the return water amount is detected through a flowmeter, and when the return water amount is lower than the total circulation amount by 2-5%, the return water amount is fed back to a water replenishing pump;
heating mode in winter
In a winter heating operation mode, normal temperature and pressure air is subjected to primary compression by an air compressor to reach 75-95 ℃, enters a primary heat exchanger to exchange heat with cooling water at 30-35 ℃, enters a secondary compression air compressor and a tertiary compression air compressor to reach 100-120 ℃ after heat exchange, enters the secondary heat exchanger and the tertiary heat exchanger to exchange heat after compression, and finally enters an oxygen generator after tertiary compression and cooling;
the temperature of the cooling water entering the primary heat exchanger is 65-75 ℃ after heat exchange; the cooling water entering the second-stage heat exchanger and the third-stage heat exchanger is heated to 80-90 ℃ after heat exchange, enters a water bath type gasifier to heat a low-temperature air source of an oxygen production process, the temperature is reduced to 60-70 ℃ after heat exchange, the low-temperature air source flows out, is mixed with the effluent water of 65-75 ℃ after heat exchange with the first-stage heat exchanger, the mixed hot water enters a heat supply user, and the water temperature is reduced to 40-50 ℃ after heat supply; wherein, part of the return water enters a heat pump unit as a driving heat source, the water with the temperature of 65-75 ℃ from the primary heat exchanger is heated to 80-90 ℃ and is supplied to a water bath type gasifier for use, and the rest of the low-temperature water enters a cooling tower to be cooled to 30-35 ℃ and is reused as cooling water of an air compressor; the system detects the amount of return water through a flowmeter, and when the amount of return water is lower than the total circulation amount by 2-5%, the return water is fed back to a water replenishing pump for water replenishing;
thirdly, in spring and autumn, the non-refrigeration and non-heating mode
Under a spring and autumn non-refrigeration non-heating operation mode, normal temperature and normal pressure air is subjected to primary compression by an air compressor, then the temperature of the air reaches 75-95 ℃, the air enters a primary heat exchanger to exchange heat with cooling water at 30-35 ℃, the temperature of the compressed air after heat exchange is 35-40 ℃, the air enters the air compressor to be subjected to secondary compression and tertiary compression by the air compressor, 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;
cooling water entering a primary heat exchanger is subjected to heat exchange, and the temperature is 65-75 ℃; the cooling water entering the secondary heat exchanger and the tertiary heat exchanger is heated to about 80-90 ℃ through heat exchange, the 80-90 ℃ outlet water of the secondary heat exchanger and the tertiary heat exchanger is mixed with the 65-75 ℃ outlet water of the primary heat exchanger, the mixed hot water with the temperature of 75-85 ℃ enters a water bath type gasifier to heat a low-temperature air source, and the temperature is reduced to 45-60 ℃ after heat exchange; then the mixture enters a cooling tower to be cooled to 30-35 ℃, and then flows out to be used as cooling water of an air compressor again for recycling; and the flow meter detects the return water amount, and when the return water amount is lower than 2-5% of the total amount, the return water amount is fed back to the water replenishing pump for water replenishing.
In the system and the method for multistage utilization of the waste heat of the air compressor, a main user with cache regulation on the utilization of the waste heat is a water bath type gasifier, and the water bath type gasifier is equipment used for heating a low-temperature air source in an oxygen generation process; because the extremely-low-temperature liquid gas source is heated, a large number of heat sources with higher temperature are needed in the initial heating stage, and the lower the external environment temperature is, the higher the heat source temperature is needed; the common heat source of the water bath type gasifier in the oxygen production process is low-pressure steam, the waste heat of the air compressor is used as the main heat source of the water bath type gasifier, and the insufficient part is supplemented by the steam.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides the multistage utilization system and the multistage utilization method for the waste heat of the air compressor through the design of the scheme for recovering the waste heat of the three-stage compressed air of the air compressor, so that the waste heat of the cooling water of the air compressor can be directly utilized, intermediate heat exchange equipment is reduced, excessive heat dissipation loss of the system is avoided, and the heat efficiency of the system is improved; and the method for heating the water discharged from the primary heat exchanger in a manner of driving the heat pump by partial backwater effectively utilizes the waste heat of the air compressor in multiple stages, solves the problem that the waste heat cannot be effectively utilized after the gas temperature is low after the primary compression of the air compressor and the waste heat recovery, and improves the waste heat utilization efficiency of the system. The method has the characteristics of saving energy, reducing maintenance cost and the like.
Drawings
FIG. 1 is a schematic structural diagram of the present invention.
In the figure: the system comprises an air compressor primary compression 1, an air compressor
Detailed Description
The following further describes embodiments of the present invention with reference to the accompanying drawings:
as shown in fig. 1, a multistage utilization system for waste heat of an air compressor comprises a primary compression 1 of the air compressor, a
an outlet of a primary compression 1 of the air compressor is connected with an inlet of a 4 gas side of the primary heat exchanger, an outlet of the 4 gas side of the primary heat exchanger is connected with an inlet of a
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