Method for improving waste heat utilization rate of air compressor

Abstract

The invention discloses a method for improving the waste heat utilization rate of an air compressor, which comprises the following steps of: recovering hot exhaust waste heat of the air compressor by using an air source heat pump unit, recovering working oil waste heat of the air compressor by using a heat exchanger, and supplying the hot exhaust waste heat and / or the working oil waste heat to a first user side through a first heat supply unit; the second heat supply unit supplies heat to the first user side or provides production hot water for the first user side, hot exhaust waste heat and / or working oil waste heat are / is supplied to the second user side through the second heat supply unit, and domestic hot water is provided for the second user side. The heat pump unit is used for recycling waste heat of hot exhaust air of the air compressor, the heat exchanger is used for recycling oil heat of the air compressor, and the waste heat recycling rate of the air compressor is increased; the second heat supply unit is provided with two water tanks, one water tank is hot, and the other water tank is cold, so that the heat consumption influence of water replenishing on a second user side is reduced; flexible use of hot exhaust waste heat and working oil waste heat can be achieved, independent work can be achieved, the hot exhaust waste heat and the working oil waste heat can supply heat or heat living water together, and the recycling rate of the waste heat of the air compressor is increased.

Description

Technical Field

[0001] The invention relates to the technical field of waste heat recovery, and in particular to a method for improving the utilization rate of waste heat of an air compressor. Background Art

[0002] Compressed air is the second largest power source after electricity. Air compressors are widely used in various fields. According to statistics, the power consumption of air compressors accounts for 10% of industrial energy consumption. During the operation of the air compressor, a large amount of heat will be generated due to air compression, mechanical friction, and motor heating. According to authoritative testing, only 10% of the power consumed by the air compressor is converted into compressed air potential energy, and the remaining 90% is converted into heat energy (nearly 85% of the heat can be recycled). In order to ensure the normal and stable operation of the air compressor and maintain the normal operating temperature of the air compressor, this heat is usually discharged into the external environment, causing energy waste and environmental thermal pollution. Therefore, it is very important to recover and reasonably utilize the heat generated during the operation of the air compressor.

[0003] Using air compressor waste heat for domestic hot water is the most common and effective energy-saving measure. The current common air compressor waste heat recovery system uses a waste heat recovery heat exchanger to recover heat, that is, it is connected to the air compressor through a bypass oil or gas line and recovers the heat it carries. A water pump is used to send the water in the insulated hot water tank to the waste heat recovery heat exchanger for heating, and then it returns to the insulated hot water tank after heating. The water is circulated and heated until all the water in the insulated hot water tank reaches the specified temperature, and then the hot water in the insulated hot water tank is sent to the user by the hot water supply pump.

[0004] The above-mentioned circulation heating method has the following problems in actual operation: First, when replenishing water, cold water is generally directly added to the insulated water tank, which causes the hot water in the insulated water tank to become cold again and needs to be heated again until all the water in the water tank is heated to the specified temperature. This takes a considerable amount of time, during which hot water that meets the temperature requirements cannot be provided at any time. In addition, this waste heat recovery method cannot completely replace the original cooling system of the air compressor in actual operation, so that most of the waste heat is dissipated into the external environment through the air compressor's own cooling system, and the waste heat utilization rate of the air compressor is low. Therefore, how to provide hot water that meets the temperature requirements in a timely and stable manner without affecting the stable operation of the air compressor and maximize the use of the "free" heat of the air compressor waste heat has become an important technical issue in the field of waste heat recovery and utilization of air compressors. Summary of the invention

[0005] In view of this, the present invention proposes a method for improving the waste heat utilization rate of an air compressor, which greatly improves the waste heat utilization rate of the air compressor and can also enable hot water users to use heat at any time.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The method for improving the utilization rate of waste heat of an air compressor of the present invention comprises the following steps: using an air source heat pump unit to recover the waste heat of hot exhaust air of the air compressor, using a heat exchanger to recover the waste heat of working oil of the air compressor, supplying the waste heat of hot exhaust air and / or working oil to a first user end through a first heating unit, heating the first user end or providing production hot water, and supplying the waste heat of hot exhaust air and / or working oil to a second user end through a second heating unit, providing domestic hot water to the second user end; The first heating unit comprises a circulation loop formed by sequentially connecting the heat pump unit, the circulating hot water supply pipeline, the first user end and the circulating hot water return pipeline, the heat pump unit is an air source heat pump unit or an air source-water source composite heat pump unit; the hot air outlet of the air compressor is located at the air inlet of the heat pump unit; The second heating unit comprises a second user end, a first water tank and a second water tank, the first water tank is connected to the water channel inlet of the heat exchanger through a cold water heating pipe, the water channel outlet of the heat exchanger is connected to the second water tank through a hot water heating pipe, the second water tank is connected to the second user end through a hot water supply pipe, and the first water tank is connected to the hot water return pipe and the tap water pipe of the second user end; The outlet end of the cold water heating pipeline is also connected to a first branch pipeline, the first branch pipeline is connected to the outlet end of the circulating hot water return pipeline, and a third valve and a fifth valve connected in parallel with the third valve are arranged on the first branch pipeline; the water inlet of the hot water heating pipeline is connected to the water inlet end of the circulating hot water supply pipeline through a second branch pipeline, and a fourth valve and a sixth valve connected in parallel with the fourth valve are arranged on the second branch pipeline; The hot water supply pipe is provided with a hot water supply pump group, the cold water heating pipe is provided with a cold water pump group, and the circulating hot water return pipe is provided with a circulating pump group; the outlet of the tap water pipe is provided with an eleventh valve, and the inlet of the cold water heating pipe is provided with a ninth valve; A first valve is provided on the cold water heating pipe located on the front side of the first pipe, and a second valve is provided on the hot water heating pipe located on the rear side of the second pipe; an eighth valve is provided on the circulating hot water supply pipe, and a seventh valve is provided on the circulating hot water return pipe.

[0007] The beneficial effects are: the present invention changes the traditional circulating air compressor waste heat recovery system, utilizes a heat pump unit (an air source heat pump unit or a composite heat pump unit with an air source) to recover the hot exhaust waste heat of the air compressor, utilizes a heat exchanger to recover the oil heat of the air compressor, and improves the waste heat recovery rate of the air compressor.

[0008] The second heating unit of the present invention recovers the heat generated by the working oil of the air compressor through a heat exchanger. The second heating unit has two water tanks. Cold water enters the heat exchanger from the first water tank, flows back to the second water tank after the heat exchanger, and is directly added to the first water tank when replenishing water. The second water tank provides real-time hot water for the second user end, thereby realizing the second user end to take heat at any time and reducing the impact of replenishing water on the heat consumption of the second user end.

[0009] The present invention uses the first branch pipe and the second branch pipe to realize the connection between the cold water heating pipe, the hot water heating pipe, the circulating hot water return pipe, and the circulating hot water supply pipe. In actual operation, not only can the waste heat of the hot exhaust air of the air compressor be used to heat the first user end, but the waste heat of the working oil of the air compressor can also be used to directly heat the first user end, thereby improving the utilization rate of the waste heat of the working oil; the waste heat of the hot exhaust air of the air compressor can also be used to heat domestic water, thereby providing domestic hot water for the second user end, thereby making the entire system more flexible.

[0010] Preferably, the first heating unit is connected to a water replenishment unit, the water replenishment unit comprises a softened water treatment pipeline connected to tap water and a third water tank, the softened water treatment pipeline is provided with a softened water treatment device, the third water tank is connected to the circulating hot water return pipeline through a water replenishment pipeline, and a water replenishment pump group is provided on the water replenishment pipeline to provide water replenishment power. The replenishment water is softened water to reduce the impact of water quality on the pipeline and the pump group.

[0011] Preferably, the water replenishment pump group, hot water supply pump group, cold water pump group and circulation pump group are all two or more groups. In the present invention, each pump group is two or more groups, which can be one standby and one in use or one standby and two in use, etc., to ensure the normal operation of the entire system and reduce the downtime rate caused by failures.

[0012] Preferably, the bottom outlet of the second water tank is connected to the cold water heating pipeline through a pipeline with a tenth valve. When the water temperature of the second water tank drops to a certain temperature, the tenth valve can be opened to reheat the water in the second water tank to ensure the temperature of the domestic hot water at the second user end.

[0013] Preferably, a pressure regulating branch with a pressure regulating valve is provided between the circulating hot water supply pipe and the circulating hot water return pipe. The present invention can utilize the pressure regulating valve to balance the pressure between the return water and the supply water.

[0014] Compared with the prior art, the present invention changes the traditional circulating air compressor waste heat recovery system, uses a heat pump unit (air source heat pump unit or a composite heat pump unit with an air source) to recover the hot exhaust waste heat of the air compressor, and uses a heat exchanger to recover the oil heat of the air compressor, thereby improving the waste heat recovery rate of the air compressor. For an air source heat pump unit or a composite heat pump unit with an air source, the higher the ambient temperature, the higher the energy efficiency of the air source heat pump, and the hot exhaust waste heat temperature discharged by the air compressor is as high as 50°C or more, providing the air source heat pump unit with hot air at a higher temperature, greatly improving the energy efficiency of the air source heat pump unit. The present invention combines an air compressor unit with an air source heat pump unit, improves the recovery rate of waste heat from the air compressor, improves the energy efficiency of the heat pump unit, reduces its operating energy consumption, reduces environmental pollution, and reduces the operating costs of the enterprise.

[0015] The second heating unit of the present invention recovers the heat generated by the working oil of the air compressor through a heat exchanger. The second heating unit has two water tanks. Cold water enters the heat exchanger from the first water tank, flows back to the second water tank after the heat exchanger, and is directly added to the first water tank when replenishing water. The second water tank provides real-time hot water for the second user end, thereby realizing the second user end to take heat at any time and reducing the impact of replenishing water on the heat consumption of the second user end.

[0016] The present invention uses the first branch pipe and the second branch pipe to realize the connection between the cold water heating pipe, the hot water heating pipe, the circulating hot water return pipe, and the circulating hot water supply pipe. In actual operation, not only can the waste heat of the hot exhaust air of the air compressor be used to heat the first user end, but the waste heat of the working oil of the air compressor can also be used to directly heat the first user end, thereby improving the utilization rate of the waste heat of the working oil; the waste heat of the hot exhaust air of the air compressor can also be used to heat domestic water, thereby providing domestic hot water for the second user end, thereby making the entire system more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a pipeline schematic diagram of the present invention.

[0018] Figure 2 This is the operating diagram in which both the waste heat of the air compressor working oil and the waste heat of the hot exhaust air are used for the second heating unit.

[0019] Figure 3 This is the operating diagram in which both the waste heat of the air compressor working oil and the waste heat of the hot exhaust air are used for the first heating unit. DETAILED DESCRIPTION

[0020] The following is a detailed description of an embodiment of the present invention in conjunction with the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0021] It should be noted that, in the description of the present invention, relational terms such as “first” and “second” are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0022] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected" and "connection" that may appear should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] like Figure 1 As shown, the method for improving the utilization rate of waste heat of an air compressor according to the present invention utilizes an air source heat pump unit to recover the hot exhaust air waste heat of the air compressor 301, utilizes a heat exchanger 303 to recover the working oil waste heat of the air compressor (a hot oil circulation loop is formed between the heat exchanger 303 and the air compressor 301 through a pipeline), and supplies the hot exhaust air waste heat (or the hot exhaust air waste heat and the working oil waste heat in combination) to a first user end through a first heating unit to provide heating or production hot water for the first user end; supplies the working oil waste heat (or the hot exhaust air waste heat and the working oil waste heat in combination) to a second user end through a second heating unit to provide domestic hot water for the second user end; Among them, the first heating unit includes a circulation loop formed by connecting a heat pump unit 101, a circulating hot water supply pipeline 102, a first user end 103 (heating or production heat) and a circulating hot water return pipeline 104 in sequence. A circulating pump unit 105 is arranged on the circulating hot water return pipeline 104 to provide circulation power; the heat pump unit 101 is an air source heat pump unit or an air source-water source composite heat pump unit, and an exhaust duct 302 is arranged at the hot air outlet of the air compressor 301, and the air outlet of the exhaust duct 302 is directly opposite to the air inlet of the heat pump unit 101. When working, the heat pump unit 101 absorbs the cooling hot exhaust air of the air compressor 301, and indirectly transfers the heat of the cooling hot exhaust air to the softened water from the circulating hot water loop. The softened water absorbs heat and rises to 55°C to 60°C, and is provided to the first user end 103 through the circulating hot water supply pipe 102. The return water (temperature is 45°C to 50°C) of the first user end 103 enters the heat pump unit 101 again through the circulating hot water return pipe 104, thereby realizing circulating heating. Since the ambient temperature at the air inlet of the heat pump unit 101 is as high as 50°C, the energy efficiency ratio and working efficiency of the heat pump unit 101 are greatly improved, and the application scope of air source heat pumps in northern regions is expanded, with high environmental, social and economic benefits.

[0024] Combination Figure 1It can be seen that the second heating unit and the heat exchanger 303 are combined to provide domestic hot water for the second user end, which includes the second user end, the first water tank 201 (cold water tank) and the second water tank 202 (hot water tank, the water tank has an insulation layer), the first water tank 201 is connected to the water channel inlet of the heat exchanger 303 through the cold water heating pipe 207 (equipped with a cold water pump group 203), the water channel outlet of the heat exchanger 303 is connected to the second water tank 202 through the hot water heating pipe 204, the second water tank 202 is connected to the second user end through the hot water supply pipe 205, and the hot water supply pipe 205 is provided with a hot water supply pump group 206 to provide hot water for the second user end; the first water tank 201 is connected to the hot water return pipe and the tap water pipe of the second user end to achieve water replenishment; the eleventh valve F11 is provided at the outlet of the tap water pipe, and the ninth valve is provided at the inlet of the cold water heating pipe 207. During operation, cold water is added to the first water tank 201. The water in the first water tank 201 enters the heat exchanger 303 through the cold water heating pipe 207, absorbs the heat of the high-temperature working oil flowing through the heat exchanger 303, and the temperature of the cold water can be raised to 60°C after absorbing the oil heat and enters the second water tank 202 through the hot water heating pipe 204, and then is supplied to the second user end through the hot water supply pipe 205 and the hot water supply pump group 206, ensuring the domestic hot water for the second user end. The second heating unit of the present invention has two water tanks. Cold water enters the heat exchanger 303 from the first water tank 201, flows back to the second water tank 202 after passing through the heat exchanger 303, and is directly added to the first water tank 201 during water replenishment. The second water tank 202 provides real-time hot water for the second user end, thereby realizing the second user end to take heat at any time, reducing the impact of water replenishment on the heat use of the second user end.

[0025] Combination Figure 1 It can be seen that the outlet end of the cold water heating pipe 207 is also connected to the first branch pipe 401, the first branch pipe 401 is connected to the outlet end of the circulating hot water return pipe 104, and the first branch pipe 401 is provided with a third valve F3 and a fifth valve F5 connected in parallel with the third valve F3; the water inlet of the hot water heating pipe 204 is connected to the water inlet end of the circulating hot water supply pipe 102 through the second branch pipe 402, and the second branch pipe 402 is provided with a fourth valve F4 and a sixth valve F6 connected in parallel with the fourth valve F4; the cold water heating pipe 207 located at the front side of the first branch pipe 401 is provided with a first valve F1, and the hot water heating pipe 204 located at the rear side of the second branch pipe 402 is provided with a second valve F2; the circulating hot water supply pipe 102 is provided with an eighth valve F8, and the circulating hot water return pipe 104 is provided with a seventh valve F7. The present invention utilizes the first branch pipe 401 and the second branch pipe 402 to realize the connection between the cold water heating pipe 207 , the hot water heating pipe 204 and the circulating hot water return pipe 104 and the circulating hot water supply pipe 102 .

[0026] The working conditions under which both the exhaust air waste heat and the working oil waste heat are supplied to the first user end are as follows: when the second water tank 202 is full and the hot water temperature reaches 60°C, the heating of the cold water can be stopped, and the heat of the high-temperature working oil can be used for the first user end 103 to meet the heat demand of the first user end 103. The specific working process is: close the first valve F1, the second valve F2, the third valve F3 and the fourth valve F4, open the sixth valve F6, the eighth valve F8, the seventh valve F7 and the fifth valve F5, the outlet of the circulating hot water return pipe 104 is divided into two routes, one route directly enters the heat pump unit 101, and then enters the circulating hot water supply pipe 102 through the heat pump unit 101; the other route enters the heat exchanger 303 through the fifth valve F5, the hot water from the heat exchanger 303 enters the circulating hot water supply pipe 102 through the sixth valve F6, and the hot water from the heat pump unit 101 is also merged into the circulating hot water supply pipe 102, so as to realize the simultaneous heating of the working oil waste heat of the air compressor 301 and the hot exhaust waste heat, see details Figure 3 .

[0027] During off-peak hours or when heat is quickly taken out, the condition in which the waste heat of hot exhaust air and the waste heat of working oil are jointly supplied to the second user end can be operated. Under this condition: the first valve F1, the second valve F2, the third valve F3 and the fourth valve F4 are opened, and the fifth valve F5, the sixth valve F6, the seventh valve F7 and the eighth valve F8 are closed. The cold water from the first water tank 201 is divided into two paths. One path enters the heat exchanger 303, and after heat exchange, enters the second water tank 202 through the hot water heating pipe 204; the other path enters the heat pump unit 101 through the first branch pipe 401 where the third valve F3 is located, and after heat exchange, it merges through the fourth valve F4 and the second branch pipe 402 to enter the hot water heating pipe 204, thereby achieving efficient heating. For details, see Figure 2 .

[0028] The present invention can not only utilize the waste heat of hot exhaust air of the air compressor 301 to heat the first user end 103, but also utilize the waste heat of the working oil of the air compressor 301 to directly heat the first user end 103, thereby improving the utilization rate of the waste heat of the working oil; the waste heat of hot exhaust air of the air compressor 301 can also be used to heat domestic water, thereby providing domestic hot water for the second user end, further improving the recovery rate of the waste heat of the air compressor 301, realizing efficient utilization of energy, reducing the consumption of electricity and fossil energy, and helping to reduce environmental pollution and reduce the operating costs of enterprises.

[0029] Combination Figure 1 It can be seen that the water replenishment unit includes a softened water treatment pipeline 501 connected to tap water and a third water tank 502 (a water replenishment tank). The softened water treatment pipeline 501 is provided with a softened water treatment device. The third water tank 502 is connected to the circulating hot water return pipeline 104 through a water replenishment pipeline 503, and a water replenishment pump group 504 is provided on the water replenishment pipeline 503. The water replenishment pump group 504 is used to provide water replenishment power.

[0030] During actual installation, the water replenishment pump group 504, the hot water supply pump group 206, the cold water pump group 203 and the circulation pump group 105 are all two groups (or more than two groups), and each pump group can be used as a backup to ensure the normal operation of the entire system.

[0031] As can be seen from the figure, the bottom outlet of the second water tank 202 is connected to the cold water heating pipe 207 through a pipeline with a tenth valve F10. When the water temperature of the second water tank 202 drops to a certain temperature, the tenth valve F10 can be opened to reheat the water in the second water tank 202 to ensure the temperature of the domestic hot water at the second user end.

[0032] In actual installation, the water supply pump group 504, the hot water supply pump group 206, the cold water pump group 203 and the circulation pump group 105 use the same pump group. Take the water supply pump group 504 as an example: the water supply pump group 504 includes a water pump, a butterfly valve and a filter are provided on the water inlet side of the water pump, and a check valve and a butterfly valve are provided on the outlet side. Figure 1 .

[0033] During actual installation, the circulating hot water return pipe 104 and the circulating hot water supply pipe 102 are connected via a pressure regulating branch, and a pressure regulating valve 106 is provided on the pressure regulating branch to balance the pressure between the inlet water and the return water; the first valve F1 to the eleventh valve F11 are all electric butterfly valves.

[0034] Finally, it should be emphasized that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments without creative work, or replace some of the technical features therein with equivalents. Therefore, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for improving the utilization rate of waste heat of an air compressor, characterized in that: The method comprises: utilizing an air source heat pump unit to recover the hot exhaust air waste heat of an air compressor, utilizing a heat exchanger to recover the working oil waste heat of the air compressor, supplying the hot exhaust air waste heat and / or the working oil waste heat to a first user end through a first heating unit, heating the first user end or providing production hot water, and supplying the hot exhaust air waste heat and / or the working oil waste heat to a second user end through a second heating unit, providing domestic hot water to the second user end; The first heating unit comprises a circulation loop formed by sequentially connecting the heat pump unit, the circulating hot water supply pipeline, the first user end and the circulating hot water return pipeline, the heat pump unit is an air source heat pump unit or an air source-water source composite heat pump unit; the hot air outlet of the air compressor is located at the air inlet of the heat pump unit; The second heating unit comprises a second user end, a first water tank and a second water tank, the first water tank is connected to the water channel inlet of the heat exchanger through a cold water heating pipe, the water channel outlet of the heat exchanger is connected to the second water tank through a hot water heating pipe, the second water tank is connected to the second user end through a hot water supply pipe, and the first water tank is connected to the hot water return pipe and the tap water pipe of the second user end; The outlet end of the cold water heating pipeline is also connected to a first branch pipeline, the first branch pipeline is connected to the outlet end of the circulating hot water return pipeline, and a third valve and a fifth valve connected in parallel with the third valve are arranged on the first branch pipeline; the water inlet of the hot water heating pipeline is connected to the water inlet end of the circulating hot water supply pipeline through a second branch pipeline, and a fourth valve and a sixth valve connected in parallel with the fourth valve are arranged on the second branch pipeline; The hot water supply pipe is provided with a hot water supply pump group, the cold water heating pipe is provided with a cold water pump group, and the circulating hot water return pipe is provided with a circulating pump group; the outlet of the tap water pipe is provided with an eleventh valve, and the inlet of the cold water heating pipe is provided with a ninth valve; A first valve is provided on the cold water heating pipe located on the front side of the first pipe, and a second valve is provided on the hot water heating pipe located on the rear side of the second pipe; an eighth valve is provided on the circulating hot water supply pipe, and a seventh valve is provided on the circulating hot water return pipe.

2. The method for improving the utilization rate of waste heat of an air compressor according to claim 1, characterized in that: The first heating unit is connected to the water replenishment unit, and the water replenishment unit includes a softened water treatment pipeline connected to tap water and a third water tank. The softened water treatment pipeline is provided with a softened water treatment device. The third water tank is connected to the circulating hot water return pipeline through a water replenishment pipeline, and a water replenishment pump group is provided on the water replenishment pipeline.

3. The method for improving the utilization rate of waste heat of an air compressor according to claim 2, characterized in that: The water replenishment pump group, hot water supply pump group, cold water pump group and circulation pump group are all two or more groups.

4. The method for improving the utilization rate of waste heat of an air compressor according to claim 1, characterized in that: The bottom outlet of the second water tank is connected to the cold water heating pipeline through a pipeline with a tenth valve.

5. The method for improving the utilization rate of waste heat of an air compressor according to claim 1, characterized in that: A pressure regulating branch with a pressure regulating valve is arranged between the circulating hot water supply pipeline and the circulating hot water return pipeline.

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