Multi-stage waste heat recovery device for air compressors

Abstract

This utility model discloses a multi-stage waste heat recovery device for air compressors, including a housing. Inside the housing, there is an oil-gas separator, a shell-and-tube heat exchanger, and a plate heat exchanger. The oil-gas separator has a heat-conducting coil spirally wound around its outer wall. The cold water inlet of the heat-conducting coil extends to the outside of the housing. A support ring is installed at the top of the housing cavity. The shell-and-tube heat exchanger is installed through the support ring, with its inlet and outlet extending to the outside of the housing. The hot water outlet of the heat-conducting coil is sealed to the inlet of the shell-and-tube heat exchanger via a rigid water pipe. The outlet of the shell-and-tube heat exchanger is connected to the inlet of the plate heat exchanger via a rigid water pipe. The hot water outlet of the plate heat exchanger extends to the outside of the housing and connects to a water collection tank. The oil inlet of the oil-gas separator extends to the outside of the housing to receive the cooling oil from the air compressor. Its oil outlet is connected to the oil inlet of the plate heat exchanger via a rigid oil pipe. The oil outlet of the plate heat exchanger extends to the outside of the housing.

Description

Technical Field

[0001] This utility model relates to the field of air compressor technology, specifically to a multi-stage waste heat recovery device for air compressors. Background Technology

[0002] As a widely used power equipment in the industrial field, air compressors generate a large amount of high-temperature cooling oil (80-120℃) and compressed air (60-100℃) during operation. It is estimated that 80%-90% of the electrical energy input to the air compressor is eventually converted into heat energy, of which about 70% can be reused through waste heat recovery technology.

[0003] In existing technologies, traditional waste heat recovery methods mostly adopt single-stage heat exchange structures, which can only recover a portion of the heat. The heat exchange efficiency is low and the thermal energy utilization rate is insufficient. The single-stage heat exchange structure cannot utilize waste heat in different temperature ranges step by step (such as the heat of the outer wall of the oil-gas separator, the heat of compressed air, and the heat of cooling oil), resulting in a low final hot water temperature (usually only 50-60℃), which is difficult to meet the high-temperature requirements of industrial or domestic hot water (such as above 70℃). Utility Model Content

[0004] The purpose of this invention is to provide a multi-stage waste heat recovery device for air compressors, in order to solve the problems of low heat exchange efficiency, insufficient thermal energy utilization, and inability to utilize waste heat in different temperature ranges in the traditional waste heat recovery method mentioned in the background art, which adopts a single-stage heat exchange structure.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a multi-stage waste heat recovery device for air compressors, comprising a housing, inside which are installed an oil-gas separator, a shell-and-tube heat exchanger, and a plate heat exchanger. A heat-conducting coil is spirally wound around the outer wall of the oil-gas separator. The cold water inlet of the heat-conducting coil extends to the outside of the housing for connecting to an external cold water source and performing primary heat exchange through contact with the outer wall of the oil-gas separator. A support ring is installed at the top of the housing cavity. The shell-and-tube heat exchanger is installed through the support ring, with its inlet and outlet extending to the outside of the housing, forming a second-stage heat exchange channel. The hot water outlet of the heat-conducting coil is connected to the inlet of the shell-and-tube heat exchanger via a rigid water pipe. A sealed connection allows the primary heated cold water to be introduced into a shell-and-tube heat exchanger for secondary heat exchange. The outlet of the shell-and-tube heat exchanger is connected to the inlet of the plate heat exchanger via a rigid water pipe. The hot water outlet of the plate heat exchanger extends outside the casing and connects to a collection tank to complete the tertiary heat exchange. The oil inlet of the oil-gas separator extends outside the casing to connect to the cooling oil of the air compressor. Its oil outlet is connected to the oil inlet of the plate heat exchanger via a rigid oil pipe. The oil outlet of the plate heat exchanger extends outside the casing. The cold water source is gradually heated through a three-stage series connection. The heat-conducting coil constitutes the primary recovery unit, the shell-and-tube heat exchanger constitutes the secondary recovery unit, and the plate heat exchanger constitutes the tertiary recovery unit.

[0006] Based on the preferred embodiment of this technical solution, a valve is installed on the rigid water transmission pipeline for opening and closing the inlet end of the shell-and-tube heat exchanger.

[0007] Based on the preferred embodiment of this technical solution, a rigid branch pipe is installed on the rigid water supply pipeline one, the outlet of the branch pipe is connected to the rigid water supply pipeline two, and a valve two is installed on the branch pipe to control the opening and closing of the branch pipe.

[0008] Based on the preferred embodiment of this technical solution, a valve is installed on the rigid water transmission pipeline 2 to open and close the outlet end of the shell-and-tube heat exchanger.

[0009] Based on the preferred embodiment of this technical solution, the front end of the box is equipped with an openable door with an observation window, and the gap between the door and the box is sealed by a sealing strip.

[0010] In a preferred embodiment of this technical solution, the inner wall of the support ring is provided with an annular groove, and an elastic element is provided in the groove.

[0011] Based on the preferred embodiment of this technical solution, the observation window is a double-layer tempered glass structure, with an oleophobic coating applied to the inner glass surface.

[0012] Compared with the prior art, the beneficial effects of this utility model are:

[0013] 1. Through a three-stage series heat exchange structure (heat-conducting coil, shell-and-tube heat exchanger, plate heat exchanger), the cold water source is gradually heated (ultimately reaching 70-90℃), and the waste heat of the oil-gas separator, compressed air and cooling oil is utilized step by step to improve the heat recovery rate and reduce energy waste.

[0014] 2. The valves (valve one, two, and three) between each heat exchange unit support flexible opening and closing, which facilitates the adjustment of the flow direction of cold water to meet different heat exchange needs. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of one embodiment of the multi-stage waste heat recovery device for air compressors according to this utility model;

[0016] Figure 2 This is a front view of the present utility model;

[0017] Figure 3 This is a schematic diagram of the structure of the primary recycling unit of this utility model;

[0018] Figure 4 This is a schematic diagram of the structure of the secondary recycling unit of this utility model;

[0019] Figure 5 This is a schematic diagram of the branch pipe structure of this utility model.

[0020] In the diagram: 1. Housing; 2. Oil-gas separator; 3. Shell-and-tube heat exchanger; 4. Plate heat exchanger; 5. Heat transfer coil; 6. Support ring; 7. Rigid water supply pipe one; 8. Rigid water supply pipe two; 9. Water collection tank; 10. Rigid oil supply pipe; 11. Valve one; 12. Branch pipe; 13. Valve two; 14. Valve three; 15. Observation window; 16. Door. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] Please see Figures 1-5This utility model provides an embodiment of a multi-stage waste heat recovery device for air compressors, including a housing 1. Inside the housing 1 are an oil-gas separator 2, a shell-and-tube heat exchanger 3, and a plate heat exchanger 4. A heat-conducting coil 5 is spirally wound around the outer wall of the oil-gas separator 2. The cold water inlet of the heat-conducting coil 5 extends to the outside of the housing 1, allowing access to an external cold water source for primary heat exchange through contact with the outer wall of the oil-gas separator 2. A support ring 6 is installed at the top of the housing 1 cavity. The shell-and-tube heat exchanger 3 is installed through the support ring 6, with its inlet and outlet extending to the outside of the housing 1, forming a second-stage heat exchange channel. The hot water outlet of the heat-conducting coil 5 is sealed to the inlet of the shell-and-tube heat exchanger 3 via a rigid water pipe 7, allowing the cold water after primary heating to pass through. The water is introduced into the shell-and-tube heat exchanger 3 for secondary heat exchange. The outlet of the shell-and-tube heat exchanger 3 is connected to the inlet of the plate heat exchanger 4 via a rigid water pipe 8. The hot water outlet of the plate heat exchanger 4 extends outside the housing 1 and connects to the water collection tank 9, completing the third stage of heat exchange. The oil inlet of the oil-gas separator 2 extends outside the housing 1 to connect to the cooling oil of the air compressor. Its oil outlet is connected to the oil inlet of the plate heat exchanger 4 via a rigid oil pipe 10. The oil outlet of the plate heat exchanger 4 extends outside the housing 1. The cold water source is gradually heated through a three-stage series connection. The heat transfer coil 5 constitutes the first-stage recovery unit, the shell-and-tube heat exchanger 3 constitutes the second-stage recovery unit, and the plate heat exchanger 4 constitutes the third-stage recovery unit. The housing 1 is made of metal, such as stainless steel or carbon steel. A closed cavity structure is created using welding. When the air compressor is running, high-temperature cooling oil (typically 80-120℃) enters the oil-gas separator 2 through the oil inlet. Inside the oil-gas separator 2, the gas (mainly compressed air) in the cooling oil is separated from the oil through centrifugation, gravity settling, or filtration. The gas is discharged from the gas outlet, while the separated cooling oil is discharged from the oil outlet. During this process, the large amount of heat carried by the cooling oil provides a heat source for subsequent waste heat recovery. The heat-conducting coil 5 is made of metal, such as copper or stainless steel, and is fixed to the outer wall of the oil-gas separator 2 by welding or clamping. The cold water inlet of the heat-conducting coil 5 extends to the outside of the housing 1 for connecting to an external cold water source (initial temperature typically 1℃). (0-25℃) When cold water enters the heat transfer coil 5, it comes into contact with the outer wall of the oil-gas separator 2. Due to the high temperature of the outer wall of the oil-gas separator 2, heat is transferred from the oil-gas separator 2 to the cold water in the heat transfer coil 5 through heat conduction, raising the temperature of the cold water and completing the primary heat exchange. After the primary heat exchange, the temperature of the cold water can rise to 30-50℃. The support ring 6 is made of metal, such as stainless steel, and is fixed to the housing 1 by welding or bolting. The function of the support ring 6 is to provide installation support for the shell-and-tube heat exchanger 3, ensuring that the shell-and-tube heat exchanger 3 can be stably installed through the housing 1. The shell-and-tube heat exchanger 3 consists of a tube bundle and a shell. The tube bundle is made of metal, such as stainless steel tubes, and is fixed to the shell by expansion joints or welding.The hot water output end of the heat transfer coil 5 is sealed to the inlet end of the shell-and-tube heat exchanger 3 via a rigid water supply pipe 7, allowing the primary heated cold water (temperature 30-50℃) to enter the tube bundle of the shell-and-tube heat exchanger 3. Simultaneously, high-temperature compressed air (typically 60-100℃) from the air compressor enters the shell of the shell-and-tube heat exchanger 3 from the air inlet end, exchanging heat with the cold water in the tube bundle. The high-temperature compressed air transfers heat to the cold water in the tube bundle, further raising the water temperature and completing the secondary heat exchange. After the secondary heat exchange, the cold water temperature can rise to 50-70℃. The plate heat exchanger 4 is composed of a series of metal plates with a certain corrugated shape stacked together, forming thin rectangular channels between adjacent plates for heat exchange. The oil outlet end of the oil-gas separator 2 is connected to the plate heat exchanger via a rigid oil supply pipe 10. The oil inlet of plate heat exchanger 4 is connected to the cooling oil from oil-gas separator 2 (which still carries some heat after oil-gas separation, with a temperature of 60-90℃). The oil enters the plate channels of plate heat exchanger 4 and exchanges heat with hot water (50-70℃) from shell-and-tube heat exchanger 3. The cooling oil transfers heat to the hot water, further raising its temperature, completing the third stage of heat exchange. After this third stage, the hot water temperature can rise to 70-90℃, and then it is delivered to water collection tank 9 through the hot water outlet. Simultaneously, the oil outlet of plate heat exchanger 4 extends outside the housing 1 to discharge the cooled oil, which can then be recycled back into the air compressor system. The water collection tank 9 collects the heated hot water after the three-stage heat exchange, providing a water source for subsequent hot water use (such as heating and domestic hot water).

[0023] Please see Figure 2 and Figure 5 A further solution based on this embodiment is as follows: A valve 11 is installed on the rigid water supply pipeline 7 to open and close the water inlet of the shell-and-tube heat exchanger 3. The valve 11 adopts common valve types such as ball valves and gate valves. Taking the ball valve as an example, it consists of components such as valve body, valve core, valve stem and handle. There is a spherical channel inside the valve core. When the handle is rotated, it drives the valve stem and valve core to rotate, so that the spherical channel is connected to or closed with the channel of the rigid water supply pipeline 7. When water needs to be supplied to the shell-and-tube heat exchanger 3, the handle is rotated to connect the spherical channel of the valve core with the pipeline, and the water can smoothly enter the shell-and-tube heat exchanger 3. When it is necessary to stop the water supply or to carry out maintenance, the handle is rotated to close the spherical channel of the valve core with the pipeline, cutting off the water flow. By opening and closing the valve 11, the water inlet of the shell-and-tube heat exchanger 3 can be easily controlled to meet different operating requirements.

[0024] Please see Figure 2 and Figure 5A further embodiment of this solution is as follows: A rigid branch pipe 12 is installed on the rigid water supply pipe 7. The outlet of the branch pipe 12 is connected to the rigid water supply pipe 8. A valve 13 is installed on the branch pipe 12 to control its opening and closing. The branch pipe 12 is made of the same metal material as the rigid water supply pipe 7, such as stainless steel. The function of the branch pipe 12 is to divert some of the hot water from the rigid water supply pipe 7 to the rigid water supply pipe 8, thereby achieving partial bypassing or direct entry of the hot water into the plate heat exchanger. 4. For heat exchange, valve 2 13 can also be a ball valve, gate valve, or similar type. The working principle of valve 2 13 is similar to that of valve 1 11. The valve core is opened and closed by rotating the handle, thereby controlling the opening and closing of the branch pipe 12. When some hot water needs to enter the plate heat exchanger 4, and some hot water needs to enter the rigid water supply pipe 2 8 directly through the branch pipe 12, valve 2 13 is opened. When the branch pipe is not needed, valve 2 13 is closed. By opening and closing valve 2 13, water can flow flexibly into the plate heat exchanger 4 to meet different heat exchange needs.

[0025] Please see Figure 2 and Figure 5 A further solution based on this embodiment is as follows: A valve 3 14 is installed on the rigid water supply pipeline 2 8 to open and close the outlet end of the shell-and-tube heat exchanger 3. The valve 3 14 adopts the same valve type as valve 1 11 and valve 2 13. The function of valve 3 14 is to control the opening and closing of the outlet end of the shell-and-tube heat exchanger 3. When the shell-and-tube heat exchanger 3 is operating normally and it is necessary to transport the hot water after the secondary heat exchange to the plate heat exchanger 4, valve 3 14 is opened to allow the water to flow smoothly. When it is necessary to inspect, maintain or stop the secondary heat exchange of the shell-and-tube heat exchanger 3, valve 3 14 is closed to cut off the water flow. By opening and closing valve 3 14, the outlet of the shell-and-tube heat exchanger 3 can be easily controlled to ensure the safe operation of the device and the operational needs under different working conditions.

[0026] Please see Figure 1 A further solution based on this embodiment is as follows: The front end of the housing 1 is provided with an openable and closable door 16 with an observation window 15. The gap between the door 16 and the housing 1 is sealed by a sealing strip. The door 16 is made of metal, such as stainless steel, and is connected to the housing 1 by a hinge to realize the opening and closing function of the door 16. The function of the observation window 15 is to allow the operator to observe the operation of the internal components of the housing 1 without opening the door 16, such as the heat exchange status of the heat exchanger and the connection status of the pipes. The sealing strip is made of rubber, such as silicone rubber or EPDM rubber, which has good elasticity and sealing performance. When the door 16 is closed, the sealing strip is compressed between the door 16 and the housing 1, filling the gap between the two, preventing heat loss inside the housing 1 and preventing external dust, moisture, etc. from entering the housing 1, ensuring that the device operates in a relatively stable environment.

[0027] Please see Figure 4 A further solution based on this embodiment is as follows: the inner wall of the support ring 6 is provided with an annular groove, and an elastic element is provided in the groove. The shape and size of the annular groove are designed according to the specifications of the elastic element, and it is generally a semi-circular groove. The elastic element is generally made of elastic materials such as rubber springs or metal springs. The function of the elastic element is to provide buffering and support when the shell-and-tube heat exchanger 3 is installed on the support ring 6, reduce the hard collision between the shell-and-tube heat exchanger 3 and the support ring 6 due to vibration or thermal expansion during operation, and protect the shell-and-tube heat exchanger 3 and the support ring 6 from damage. When the shell-and-tube heat exchanger 3 is subjected to external force, the elastic element can undergo elastic deformation to absorb and disperse the external force, and ensure the stability of the installation of the shell-and-tube heat exchanger 3.

[0028] Please see Figure 1 A further solution based on this embodiment is as follows: the observation window 15 is a double-layer tempered glass structure, with an oleophobic coating applied to the inner glass surface. Generally, a hollow layer is formed between the double-layer tempered glass or filled with an inert gas, such as argon. Tempered glass has high strength and safety, and is not easily broken when subjected to external impact. Even if it breaks, it will form particles, reducing injury to operators. The hollow layer or inert gas filling can play a role in heat insulation and sound insulation. The oleophobic coating is made of materials such as organosilicon or fluorocarbon. The function of the oleophobic coating is to make the glass surface oleophobic. When oil, dust, etc. adhere to the glass surface, the oil and dust are not easy to adhere, making it easy for operators to wipe clean with cleaning cloths and other tools, maintaining the clarity of the observation window 15.

[0029] Working principle: When the air compressor starts running, high-temperature cooling oil (temperature is usually 80-120℃) enters the oil-gas separator 2 through the oil inlet. At the same time, external cold water enters the heat-conducting coil 5 through the cold water inlet. The heat-conducting coil 5 is spirally wound around the outer wall of the oil-gas separator 2. The cold water comes into contact with the high-temperature outer wall of the oil-gas separator 2. Through heat conduction, heat is transferred from the oil-gas separator 2 to the cold water in the heat-conducting coil 5, completing the primary heat exchange. The temperature of the cold water rises to 30-50℃.

[0030] After primary heat exchange, the cold water is transported from the hot water output end of the heat transfer coil 5 to the shell-and-tube heat exchanger 3 through the rigid water supply pipe 7. If water needs to be supplied to the shell-and-tube heat exchanger 3, the operator rotates the handle of valve 11 on the rigid water supply pipe 7 to connect the ball channel of the valve core with the pipe, and the water flows smoothly into the shell-and-tube heat exchanger 3. If it is necessary to stop the water supply or perform maintenance, the operator rotates the handle to close the ball channel of the valve core with the pipe, cutting off the water flow. In addition, according to actual needs, by controlling the opening and closing of valve 13 on the branch pipe 12 on the rigid water supply pipe 7, some of the hot water transported from the rigid water supply pipe 7 can be diverted to the rigid water supply pipe 8, so that the hot water can directly enter the plate heat exchanger 4 for heat exchange.

[0031] Hot water flows inside the tube bundle of the shell-and-tube heat exchanger 3. At the same time, high-temperature compressed air (usually 60-100℃) from the air compressor enters the shell of the shell-and-tube heat exchanger 3 from the air inlet end and exchanges heat with the cold water inside the tube bundle. The high-temperature compressed air transfers heat to the cold water inside the tube bundle, raising the temperature of the cold water to 50-70℃, completing the secondary heat exchange. When the shell-and-tube heat exchanger 3 is operating normally and it is necessary to transport the hot water after the secondary heat exchange to the plate heat exchanger 4, valve 14 on the rigid water supply pipe 2 8 is opened to allow the water to flow smoothly. When it is necessary to inspect, maintain, or stop the secondary heat exchange of the shell-and-tube heat exchanger 3, valve 14 is closed to cut off the water flow.

[0032] The cooling oil discharged from the oil outlet of the oil-gas separator 2 (which still carries a certain amount of heat after oil-gas separation, with a temperature of 60-90℃) enters the plate channel of the plate heat exchanger 4 through the rigid oil pipeline 10. It exchanges heat with the hot water (temperature of 50-70℃) delivered from the shell-and-tube heat exchanger 3. The cooling oil transfers heat to the hot water, further raising the temperature of the hot water to 70-90℃, completing the third stage of heat exchange. After the third stage of heat exchange, the hot water is delivered to the water collection tank 9 through the hot water output end of the plate heat exchanger 4, providing a water source for subsequent hot water utilization. At the same time, the cooling oil, whose temperature has decreased after heat exchange, is discharged from the oil outlet of the plate heat exchanger 4 and returned to the air compressor system for recycling.

[0033] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-stage waste heat recovery device for an air compressor, characterized by: The enclosure includes a housing (1), inside which are installed an oil-gas separator (2), a shell-and-tube heat exchanger (3), and a plate heat exchanger (4). The outer wall of the oil-gas separator (2) is spirally coiled with a heat-conducting coil (5). The cold water inlet of the heat-conducting coil (5) extends to the outside of the housing (1) to connect to an external cold water source and perform primary heat exchange through contact with the outer wall of the oil-gas separator (2). A support ring (6) is installed at the top of the housing (1). The shell-and-tube heat exchanger (3) is installed through the support ring (6), and its inlet and outlet ends extend to the outside of the housing (1) to form a second-stage heat exchange channel. The hot water outlet of the heat-conducting coil (5) is connected to a rigid conveyor. Water pipe 1 (7) is sealed to the inlet of shell-and-tube heat exchanger (3) so that the cold water after primary heating is introduced into shell-and-tube heat exchanger (3) for secondary heat exchange. The outlet of shell-and-tube heat exchanger (3) is connected to the inlet of plate heat exchanger (4) through rigid water pipe 2 (8). The hot water outlet of plate heat exchanger (4) extends to the outside of box (1) and is connected to water collection tank (9) to complete the third stage of heat exchange. The oil inlet of oil-gas separator (2) extends to the outside of box (1) to connect to the cooling oil of air compressor. Its oil outlet is connected to the oil inlet of plate heat exchanger (4) through rigid oil pipe (10). The oil outlet of plate heat exchanger (4) extends to the outside of box (1). The cold water source is heated in a gradient manner through a three-stage series connection. The heat-conducting coil (5) constitutes the first-stage recovery unit, the shell-and-tube heat exchanger (3) constitutes the second-stage recovery unit, and the plate heat exchanger (4) constitutes the third-stage recovery unit.

2. The multi-stage recovery device of waste heat of air compressor according to claim 1, characterized in that: A valve (11) is installed on the rigid water supply pipe (7) to open and close the water inlet of the shell-and-tube heat exchanger (3).

3. The multi-stage recovery device of claim 2, wherein: A rigid branch pipe (12) is installed on the rigid water supply pipeline (7). The outlet of the branch pipe (12) is connected to the rigid water supply pipeline (8). A valve (13) is installed on the branch pipe (12) to control the opening and closing of the branch pipe (12).

4. The multi-stage recovery device of claim 3, wherein: A valve (14) is installed on the rigid water supply pipe 2 (8) to open and close the outlet end of the shell-and-tube heat exchanger (3).

5. The multi-stage recovery device of claim 4, wherein: The front end of the box (1) is provided with an openable box door (16) with an observation window (15), and the gap between the box door (16) and the box (1) is sealed by a sealing strip.

6. The multi-stage recovery device of claim 5, wherein: The inner wall of the support ring (6) is provided with an annular groove, and an elastic element is provided in the groove.

7. The multi-stage recovery device of claim 6, wherein: The observation window (15) is a double-layer tempered glass structure, with an oleophobic coating on the inner glass surface.

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