A gradient cooling system and an oil-injected screw air compressor

Abstract

The application belongs to the technical field of air compressors, and provides a gradient cooling system and an oil-injected screw air compressor. The gradient cooling system comprises a wind box, a fan, a low-temperature cooler and a high-temperature cooler which are respectively installed on the wind box. The low-temperature cooler is arranged at an air inlet end of the wind box, and the high-temperature cooler is arranged at an air outlet end of the wind box. An output end of the low-temperature cooler is communicated with a gas outlet end, an input end of the low-temperature cooler is communicated with an output end of the high-temperature cooler, and an input end of the high-temperature cooler is communicated with a gas source. The fan is used to drive airflow to pass through the low-temperature cooler and then flow through the high-temperature cooler. The air compressor comprises a compression host, an oil-gas separation barrel and the above-mentioned gradient cooling system. The gradient cooling system and the oil-injected screw air compressor improve the cooling efficiency through gradient cooling, and avoid shortening the service life of the cooler due to a large temperature difference.

Description

Technical Field

[0001] This invention relates to the field of air compressor technology, and in particular to a gradient cooling system and an oil-injected screw air compressor. Background Technology

[0002] Currently, the exhaust temperature of oil-injected screw air compressors under normal operating conditions is typically maintained at around 100°C. Within this temperature range, using aluminum fins as cooling elements can meet the heat exchange requirements, and the material cost and structural volume are relatively controllable. However, as compression systems develop towards higher temperature and pressure, when the exhaust temperature increases to approximately 250°C, existing aluminum fin structures face significant technical bottlenecks: on the one hand, to ensure mechanical strength and pressure resistance at high temperatures, the material thickness of the fins and related cooling components needs to be increased several times, leading to a sharp increase in the volume, weight, and manufacturing cost of the cooler; on the other hand, high temperature and high pressure conditions place higher demands on the sealing structure, and existing welding and expansion processes are difficult to operate reliably for a long time, posing a significant risk of leakage.

[0003] More importantly, the temperature difference during the cooling process has a decisive impact on the structural stability of the cooler. At a conventional exhaust temperature of 100°C, the temperature difference when cooling to the target temperature of 50°C is only 50°C; however, when the exhaust temperature reaches 250°C, the temperature difference to the same target temperature reaches 200°C, four times the former. Such a large temperature change will trigger a significant thermal expansion and contraction effect, leading to uneven thermal stress in various cooler components (especially at the connection between the fins and tube bundle). Under long-term cycling, this can easily cause cooler fin warping, tube sheet deformation, or even heat exchange tube pull-out, severely shortening the equipment's service life and reducing operational safety.

[0004] The technical problem to be solved by this invention is: how to provide a cooling system that can match air compressors with large temperature differences, high temperature and high pressure. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a gradient cooling system and an oil-injected screw air compressor, which improves cooling efficiency and avoids shortening the service life of the cooler due to excessive temperature difference by using gradient staged cooling.

[0006] The first aspect of this application is to provide a gradient cooling system, including a wind box, a fan, a low-temperature cooler, and a high-temperature cooler respectively installed on the wind box. The low-temperature cooler is located at the air inlet end of the wind box, and the high-temperature cooler is located at the air outlet end of the wind box. The output end of the low-temperature cooler is connected to the air consumption end, the input end of the low-temperature cooler is connected to the output end of the high-temperature cooler, and the input end of the high-temperature cooler is connected to the air source. The fan is used to drive the airflow through the low-temperature cooler and then through the high-temperature cooler.

[0007] The gradient cooling system of this application sets up a high-temperature cooler and a low-temperature cooler in series. The high-temperature air ejected from the air compressor enters through the input end of the high-temperature cooler, then enters the input end of the low-temperature cooler from the output end of the high-temperature cooler, and finally flows out from the output end of the low-temperature cooler. The refrigerant (cooling airflow) used for heat exchange first flows through the low-temperature cooler and then enters the high-temperature cooler. Since the low-temperature refrigerant has already been heated and its temperature increased when it flows through the low-temperature cooler, its temperature will not be too low when it flows through the high-temperature cooler. This ensures that the temperature difference does not change drastically after the heat exchange in the high-temperature cooler, thus achieving gradient and staged heat dissipation. This reduces the temperature difference between each cooling stage and avoids damage to the same stage cooler due to thermal expansion and contraction caused by excessive cooling temperature difference.

[0008] In some implementations, the cryogenic cooler is a finned cooler.

[0009] By adopting the above technical solution, since the low-temperature cooler is located at the air inlet end of the air box, it is subject to vibration during use and is more prone to dust accumulation. The finned cooler can operate efficiently, stably and reliably for a long time, and the dust accumulation can be removed by strong cleaning. Therefore, choosing a finned cooler as a low-temperature cooler can improve heat exchange efficiency and obtain a longer service life.

[0010] In some implementations, the high-temperature cooler is a finned cooler.

[0011] By adopting the above technical solution, the finned cooler has spiral fins wound around the outer surface of the cooling tube, which can increase the heat dissipation area and improve the heat dissipation efficiency. Moreover, the structure of the finned cooler is relatively simple, which helps to reduce costs.

[0012] In some embodiments, at least one transition cooler is provided between the low-temperature cooler and the high-temperature cooler, and the transition cooler is connected in series with the low-temperature cooler and the high-temperature cooler.

[0013] Using the above technical solution, when the temperature of the compressed air that needs to be cooled is high, in order to improve cooling efficiency and reduce the temperature difference between each cooling stage, one or more transition coolers can be added between the low-temperature cooler and the high-temperature cooler to perform multi-stage gradient cooling.

[0014] In some implementations, the low-temperature cooler is located on the side of the air box, and the high-temperature cooler is located on the top of the air box.

[0015] By adopting the above technical solution, this setup can make full use of space, make the cooling system structure more compact, and reduce the refrigerant flow rate to improve cooling efficiency.

[0016] In some embodiments, an air guide shroud is provided between the cryogenic cooler and the air box, with the two ends of the air guide shroud connected to the cryogenic cooler and the air box respectively, and an air collection chamber is provided inside the air guide shroud.

[0017] Using the above technical solution, the air guide shroud can guide the refrigerant (cooling airflow) through the entire air inlet side of the low-temperature cooler, thereby increasing the air inlet area and avoiding the air inlet area being concentrated at the air inlet of the fan, thus improving cooling efficiency. In addition, the air guide shroud can also guide the refrigerant after passing through the low-temperature cooler into the air box and then blow it towards the high-temperature cooler.

[0018] In some implementations, the side of the air guide shroud is provided with an air intake hole, and the air intake area of ​​the air intake hole is smaller than the air intake area of ​​the cryogenic cooler.

[0019] Using the above technical solution, the air inlet is used to supplement the low-temperature cooling air that does not flow through the low-temperature cooler, preventing the cooling air blown towards the high-temperature cooler from being too hot and affecting the cooling effect. The air inlet area of ​​the air inlet is smaller than that of the air outlet, which can ensure that most of the cooling air flows through the low-temperature cooler, thus ensuring the cooling effect of the low-temperature cooler.

[0020] In some embodiments, the fan includes a motor and a fan wheel, the motor and the fan wheel are connected by a drive, the fan wheel is built into a wind box, the air inlet of the fan wheel is arranged along the axial direction of the fan wheel and is arranged opposite to the low temperature cooler, and the air outlet of the fan wheel is arranged along the tangential direction of the fan wheel.

[0021] By adopting the above technical solution, centrifugal fans can provide cooling airflow with higher velocity and pressure, which is beneficial to improving the cooling efficiency of the cooling system.

[0022] In some implementations, the motor is located outside the bellows.

[0023] By adopting the above technical solution, this setting can protect the motor and prevent the fan from overheating and reducing its lifespan.

[0024] The second aspect of this application is to provide an oil-injected screw air compressor, including a compressor main unit, an oil-gas separator, and a gradient cooling system of any one of the above, wherein the oil injection port of the compressor main unit is connected to the output port of the oil-gas separator, and the exhaust port of the oil-gas separator is connected to the input end of a high-temperature cooler.

[0025] The oil-injected screw air compressor of this application includes any of the gradient cooling systems described above, and therefore also possesses the aforementioned beneficial effects. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the gradient cooling system according to a preferred embodiment of the present invention;

[0027] Figure 2 for Figure 1 The diagram shows another perspective of the gradient cooling system.

[0028] Figure 3 for Figure 1 The diagram shows another perspective of the gradient cooling system.

[0029] Figure 4 for Figure 1 The diagram shows the internal structure of the gradient cooling system.

[0030] Figure 5 for Figure 2 The diagram shown illustrates the structure of the gradient cooling system after the cryogenic cooler has been concealed.

[0031] Figure 6 for Figure 2 An enlarged schematic diagram of the heat exchange tubes and fins in the cryogenic cooler shown;

[0032] Figure 7 for Figure 2 The diagram shows an enlarged view of the structure of the cooling pipes and fins in the high-temperature cooler.

[0033] In the diagram: 100, gradient cooling system; 10, air box; 20, fan; 21, motor; 22, impeller; 30, low-temperature cooler; 31, heat exchange tube; 32, fins; 40, high-temperature cooler; 41, cooling tube; 42, fins; 50, air guide shroud; 51, air collection chamber; 52, air supply hole; 60, frame. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. When the number of elements is referred to as "multiple," it can be any number of two or more. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] Please see Figures 1 to 7 A gradient cooling system 100 according to a preferred embodiment of the present invention includes a wind box 10, a fan 20, a low-temperature cooler 30, and a high-temperature cooler 40 respectively installed on the wind box 10. The low-temperature cooler 30 is located at the air inlet end of the wind box 10, and the high-temperature cooler 40 is located at the air outlet end of the wind box 10. The output end of the low-temperature cooler 30 is connected to the air consumption end, and the input end of the low-temperature cooler 30 is connected to the output end of the high-temperature cooler 40. The input end of the high-temperature cooler 40 is connected to the air source. The fan 20 is used to drive the airflow through the low-temperature cooler 30 and then through the high-temperature cooler 40.

[0038] The gradient cooling system 100 of this application sets up a high-temperature cooler 40 and a low-temperature cooler 30 connected in series. The high-temperature air ejected from the air compressor enters through the input end of the high-temperature cooler 40, then enters the input end of the low-temperature cooler 30 from the output end of the high-temperature cooler 40, and finally flows out from the output end of the low-temperature cooler 30. The refrigerant (cooling airflow) used for heat exchange first flows through the low-temperature cooler 30 and then enters the high-temperature cooler 40. Since the low-temperature refrigerant has already been heated and its temperature increased when it flows through the low-temperature cooler 30, its temperature will not be too low when it flows through the high-temperature cooler 40. This ensures that the temperature difference does not change drastically after the heat exchange in the high-temperature cooler 40, thereby achieving gradient and staged heat dissipation, reducing the temperature difference of each cooling stage, and avoiding damage to the same stage cooler due to thermal expansion and contraction caused by excessive cooling temperature difference. Furthermore, the gradient cooling system 100 of this application sets a gradient cooling, so that the area (volume) of each stage cooler can be made smaller, making the structure of the heat exchange system more compact and the manufacturing cost lower. In order to achieve the same heat exchange effect, the traditional single-stage heat exchange system needs to increase the size of the cooler. The larger the volume of the cooler, the higher the production cost and difficulty, and the cooler is also more likely to be thermally deformed due to excessive temperature difference.

[0039] like Figure 6As shown, in this embodiment, the cryogenic cooler 30 is a finned 32 type cooler. Several heat exchange tubes 31 are arranged in parallel on the cryogenic cooler 30, and fins 32 are arranged between the heat exchange tubes 31. Cooling air flows through the spaces between the fins 32, carrying away the heat from the compressed air in the heat exchange tubes 31, thus achieving heat exchange. Since the cryogenic cooler 30 is located at the air inlet of the air box 10, it is subject to vibration during use and is more prone to dust accumulation. The finned 32 type cooler ensures long-term, efficient, stable, and reliable operation, and allows for powerful cleaning to remove accumulated dust. Therefore, selecting a finned 32 type cooler as the cryogenic cooler 30 can improve heat exchange efficiency and achieve a longer service life.

[0040] Optionally, the cryogenic cooler 30 is an aluminum finned cooler, because aluminum finned coolers have excellent heat exchange efficiency, are lightweight and cost-effective, corrosion resistant, not prone to scaling and dust accumulation, and easy to clean, which can improve the maintenance cost of the cryogenic cooler 30.

[0041] like Figure 7 As shown, in this embodiment, the high-temperature cooler 40 is a finned cooler. The finned cooler has multiple cooling pipes 41 arranged in parallel at intervals, and multiple layers of parallel cooling pipes 41 can also be arranged on the high-temperature cooler 40. Spiral fins 42 are wound around the outer surface of the cooling pipes 41, which can increase the heat dissipation area and improve the heat dissipation efficiency. Moreover, the structure of the finned cooler is relatively simple, which helps to reduce costs.

[0042] Optionally, the cooling pipe 41 can be made of stainless steel or copper, and the fins 42 can also be made of stainless steel or copper strips. Stainless steel or copper is used to manufacture the high-temperature cooler 40 because these two metals have high heat exchange efficiency and strong corrosion and weather resistance.

[0043] In one specific embodiment, the gradient cooling system 100 of this application further includes at least one transition cooler (not shown) disposed between the low-temperature cooler 30 and the high-temperature cooler 40, the transition cooler being connected in series with the low-temperature cooler 30 and the high-temperature cooler 40. When the temperature of the compressed air requiring cooling is high, in order to improve cooling efficiency and reduce the temperature difference between each cooling stage, one or more transition coolers can be added between the low-temperature cooler 30 and the high-temperature cooler 40 to perform multi-stage gradient cooling.

[0044] When a transition cooler is installed, the refrigerant will flow sequentially from the low-temperature cooler 30 through the transition cooler and finally through the high-temperature cooler 40 to achieve heat exchange. This ensures the cooling effect while avoiding excessive temperature differences between the coolers at each stage, thus protecting the coolers from damage due to thermal expansion and contraction.

[0045] like Figure 1 and Figure 2As shown, in this embodiment, the air inlet of the air box 10 is located on one side of the air box 10, while the air outlet of the air box 10 is located on the top of the air box 10. Correspondingly, the low-temperature cooler 30 is located on the side of the air box 10, and the high-temperature cooler 40 is located on the top of the air box 10. This arrangement can make full use of space, making the cooling system structure more compact, and can also reduce the flow rate of the refrigerant to improve cooling efficiency. In addition, this arrangement can offset the directions of the air inlet and outlet of the air box 10 to avoid hot air backflow and ensure heat dissipation effect.

[0046] Furthermore, the fan 20 is positioned between the low-temperature cooler 30 and the high-temperature cooler 40, so that the air supply method of the low-temperature cooler 30 is suction, while the air supply method of the high-temperature cooler 40 is blowing. This prevents the temperature of the area where the fan 20 is located from becoming too high, avoiding the fan 20 from operating at high temperatures and helping to extend the service life of the fan 20.

[0047] like Figure 3 and Figure 4 As shown, in one specific embodiment, an air guide shroud 50 is provided between the low-temperature cooler 30 and the air box 10. The two ends of the air guide shroud 50 are respectively connected to the low-temperature cooler 30 and the air box 10, and an air collection chamber 51 is provided inside the air guide shroud 50. The air guide shroud 50 can guide the refrigerant (cooling airflow) to pass through the entire air inlet side of the low-temperature cooler 30, thereby increasing the air inlet area and avoiding the air inlet area being concentrated at the air inlet of the fan 20, thus improving the cooling efficiency. In addition, the air guide shroud 50 can also guide the refrigerant after passing through the low-temperature cooler 30 into the air box 10 and then blow it towards the high-temperature cooler 40.

[0048] Optionally, the side of the air guide shroud 50 is provided with an air supply hole 52, and the air inlet area of ​​the air supply hole 52 is smaller than the air inlet area of ​​the low-temperature cooler 30. The air supply hole 52 is used to supplement the low-temperature cooling air that does not flow through the low-temperature cooler 30, preventing the cooling air blown towards the high-temperature cooler 40 from being too hot and affecting the cooling effect. The smaller air inlet area of ​​the air supply hole 52 ensures that most of the cooling air flows through the low-temperature cooler 30, thus ensuring the cooling effect of the low-temperature cooler 30.

[0049] Optionally, the air supply hole 52 is located at the bottom of the air guide shroud 50, which can minimize the backflow of hot air.

[0050] Furthermore, in order to facilitate air supply from the air supply hole 52, a frame 60 is provided at the bottom of the air box 10 and the air guide shroud 50. The frame 60 is used to support the air box 10 and the air guide shroud 50 so that the air supply hole 52 is separated from the mounting plane.

[0051] like Figure 4 and Figure 5As shown, specifically, the fan 20 includes a motor 21 and a fan wheel 22. The motor 21 and the fan wheel 22 are connected by a drive. The fan wheel 22 is built into the air box 10. The air inlet of the fan wheel 22 is arranged along the axial direction of the fan wheel 22, and the air inlet of the fan wheel 22 is arranged opposite to the low-temperature cooler 30. The air outlet of the fan wheel 22 is arranged tangentially to the fan wheel 22. The centrifugal fan 20 can provide cooling airflow with higher velocity and pressure, which is beneficial to improving the cooling efficiency of the cooling system.

[0052] In one embodiment, in order to protect the motor 21 and prevent the fan 20 from having a shortened service life due to excessively high operating ambient temperature, the motor 21 is installed outside the fan box 10.

[0053] This application also provides an oil-injected screw air compressor including the aforementioned gradient cooling system 100. The oil-injected screw air compressor further includes a compressor main unit (not shown) and an oil-gas separator (not shown). The oil injection port of the compressor main unit is connected to the output port of the oil-gas separator, and the exhaust port of the oil-gas separator is connected to the input end of the high-temperature cooler 40. This oil-injected screw air compressor includes the gradient cooling system 100 described above, and therefore also possesses the aforementioned beneficial effects, which will be reiterated here.

[0054] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A gradient cooling system, characterized in that, It includes a bellows (10), a fan (20) installed on the bellows (10), a low-temperature cooler (30) and a high-temperature cooler (40). The low-temperature cooler (30) is located at the air inlet of the bellows (10), and the high-temperature cooler (40) is located at the air outlet of the bellows (10). The output end of the low-temperature cooler (30) is connected to the air-consuming end, the input end of the low-temperature cooler (30) is connected to the output end of the high-temperature cooler (40), and the input end of the high-temperature cooler (40) is connected to the air source. The fan (20) is used to drive the airflow through the low-temperature cooler (30) and then through the high-temperature cooler (40).

2. The gradient cooling system according to claim 1, characterized in that, The cryogenic cooler (30) is a finned cooler.

3. The gradient cooling system according to claim 2, characterized in that, The high-temperature cooler (40) is a finned cooler.

4. The gradient cooling system according to claim 1, characterized in that, It also includes at least one transition cooler disposed between the low-temperature cooler (30) and the high-temperature cooler (40), the transition cooler being connected in series with the low-temperature cooler (30) and the high-temperature cooler (40).

5. The gradient cooling system according to claim 1, characterized in that, The low-temperature cooler (30) is located on the side of the wind box (10), and the high-temperature cooler (40) is located on the top of the wind box (10).

6. The gradient cooling system according to claim 5, characterized in that, A guide hood (50) is provided between the low-temperature cooler (30) and the air box (10). The two ends of the guide hood (50) are respectively connected to the low-temperature cooler (30) and the air box (10). An air collection chamber (51) is provided inside the guide hood (50).

7. The gradient cooling system according to claim 6, characterized in that, The side of the air guide shroud (50) is provided with an air supply hole (52), and the air inlet area of ​​the air supply hole (52) is smaller than the air inlet area of ​​the low temperature cooler (30).

8. The gradient cooling system according to claim 5, characterized in that, The fan (20) includes a motor (21) and a fan wheel (22). The motor (21) and the fan wheel (22) are connected by a drive. The fan wheel (22) is built into the air box (10). The air inlet of the fan wheel (22) is arranged along the axial direction of the fan wheel (22) and the air inlet of the fan wheel (22) is arranged opposite to the low temperature cooler (30). The air outlet of the fan wheel (22) is arranged along the tangential direction of the fan wheel (22).

9. The gradient cooling system according to claim 8, characterized in that, The motor (21) is located outside the air box (10).

10. An oil-injected screw air compressor, characterized in that, It includes a compressor host, an oil-gas separator, and a gradient cooling system (100) as described in any one of claims 1-9, wherein the oil injection port of the compressor host is connected to the output port of the oil-gas separator, and the exhaust port of the oil-gas separator is connected to the input end of the high-temperature cooler (40).

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