Screw compressor lubricating oil control system with heat pump system and method of operation thereof
By using a heat pump system and an oil-water separation system, the problem of controlling the temperature and water content of lubricating oil in screw compressors is solved, ensuring lubrication effect and compressor stability, and preventing the formation of condensate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI NUOTONG NEW ENERGY TECH CO LTD
- Filing Date
- 2023-11-02
- Publication Date
- 2026-06-26
AI Technical Summary
During the compression of steam in a screw compressor, the injected water needs to be preheated, and the temperature and water content of the lubricating oil need to be controlled within a suitable range; otherwise, it will affect the lubrication effect of the bearings and the stable operation of the compressor.
The lubricating oil control system employs a heat pump system, including a heat pump system, an oil-water separation system, and a water replenishment system. Components such as condensers and evaporators are used to heat, cool, and separate the lubricating oil and water, ensuring that the temperature of the lubricating oil and the preheating of the water meet the requirements.
Effectively control the temperature and water content of the lubricating oil to prevent bearing wear, ensure stable operation of the compressor, and avoid the formation of condensate in the compression chamber.
Smart Images
Figure CN117345636B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lubricating oil control systems, and particularly to a lubricating oil control system for a screw compressor containing a heat pump system and its operating method. Background Technology
[0002] Water vapor has a high adiabatic index, so screw compressors need to inject a small amount of water into the compression chamber during the compression process to prevent overheating of the compressor chamber and exhaust temperatures, ensuring stable compressor operation. The water injection temperature is crucial for the compression process of a steam compressor; it should be slightly lower than the saturated steam temperature of water vapor, but not too low. Excessively low water temperatures will cause condensation to form in the compression chamber, affecting the normal operation of the screw compressor and potentially damaging internal components. Therefore, the water injected into the compression chamber needs to be preheated.
[0003] The working fluid in a steam screw compressor is water vapor, and a small amount of water needs to be injected into the compression chamber. Lubricating oil needs to be injected into the bearings of the suction and discharge rotors of the steam screw compressor for cooling and lubrication. Although carbon ring seals are incorporated into the design to isolate water vapor from the lubricating oil, some water vapor entering the lubricating oil is unavoidable. Water in the bearing lubricating oil dilutes it, reducing its viscosity and thus decreasing lubrication effectiveness, increasing bearing wear. The presence of water can damage the lubricating film, further increasing bearing wear and fatigue. Water contact with metal can cause electrochemical corrosion, leading to rust and damage to the bearing surface.
[0004] Bearing lubricant becomes more viscous at lower temperatures, resulting in poorer flow within the bearing. This increases friction and wear, reducing bearing life. At low temperatures, the lubricant's thermal conductivity is also poor, hindering effective heat dissipation from the bearing. This can lead to overheating and potentially damage bearing components. At higher temperatures, the viscosity of the bearing lubricant decreases, thinning it and reducing its lubricating effect. The reduced film thickness at high temperatures further impairs its ability to isolate friction surfaces, further reducing lubrication. This leads to increased bearing friction, further temperature rise, and even lubrication failure, causing severe bearing wear or damage.
[0005] Therefore, controlling the temperature of the lubricating oil within a suitable range, controlling the water content of the lubricating oil, and preheating the water injected into the compression chamber are some of the major challenges faced in the field of screw compressors. Summary of the Invention
[0006] Steam screw compressors often face the following problems during operation: The lubricating oil inside the machine is affected by the working environment, causing changes in its water content. Excessive water content reduces lubrication and increases bearing wear. The temperature of the lubricating oil also affects lubrication; excessively low temperatures cause the oil to thicken, further reducing lubrication and causing bearing wear. Furthermore, during the operation of a screw compressor, the compressor cavity temperature must not be too high. Therefore, warm water needs to be injected into the compressor cavity to ensure stable operation. Excessively low water temperatures will cause condensation to form inside the compression chamber.
[0007] To overcome the aforementioned problems of the prior art, this application provides a screw compressor lubricating oil control system incorporating a heat pump system. This system includes a heat pump system, an oil-water separation system, and a water replenishment system for supplying water to the screw compressor. The screw compressor lubricating oil control system incorporating a heat pump system described herein can simultaneously solve the problems of water preheating and lubricating oil-water separation.
[0008] To address the aforementioned technical problems, this application provides the following technical solutions.
[0009] A screw compressor lubricating oil control system with a heat pump system includes a heat pump system, an oil-water separation system, and a water replenishment system. The heat pump system includes a heat pump compressor, a condenser, a second expansion valve, and a first evaporator, all connected in a circulating manner. The condenser cools the refrigerant flowing in the heat pump system, and the first evaporator heats the refrigerant within the heat pump circulation system. The oil-water separation system includes an oil tank, a screw compressor, a condenser, a first expansion valve, a flash evaporator, and a first evaporator, all connected in a circulating manner via a first passage. The condenser heats the lubricating oil discharged from the screw compressor, the flash evaporator flashes the heated lubricating oil to evaporate and discharge the water, and the first evaporator cools the flashed lubricating oil to the temperature required to enter the oil tank. The water replenishment system replenishes water to the screw compressor and includes a water tank, a condenser, and a screw compressor connected in sequence. The condenser heats the water from the water tank, and the heated water is delivered to the compression chamber of the screw compressor.
[0010] In one specific embodiment, the condenser is a three-fluid heat exchanger.
[0011] With the above-described structure, when the lubricating oil in the tank has a high water content, the heat pump system starts operating when the lubricating oil control system of the screw compressor containing the heat pump system is activated. Under the operation of the heat pump compressor, heat is transferred through the condenser, causing the lubricating oil in the oil-water separation system to rise in temperature before entering the flash evaporator, reaching the required temperature of the flash evaporator. After flash evaporation, the lubricating oil achieves oil-water separation, and the separated water vapor is discharged through the top of the flash evaporator. The lubricating oil with reduced water content leaves the flash evaporator and is cooled by the first evaporator before returning to the tank.
[0012] Simultaneously, the water replenishment system activates, and water flows from the tank into the condenser. Since the condenser transfers heat from the heat pump system, both the water and lubricating oil gain heat and are heated. The heated water then flows through the water replenishment system into the compression chamber of the screw compressor. This heated water helps cool the compression chamber while the screw compressor is operating, preventing condensation from forming inside the chamber due to excessively cold water.
[0013] Preferably, the water supply system also includes a water pump, which is located between the water tank and the condenser, for drawing water from the water tank and sending it into the condenser.
[0014] With the above-described structure, the water pump can quickly extract water from the tank and deliver it to the condenser. The condenser heats the water, raising its temperature to cool the compression chamber of the screw compressor. The water pump effectively increases the flow rate of water in the makeup water system, thereby improving operating efficiency.
[0015] Preferably, the heat pump system also includes a second evaporator, one end of which is connected to the condenser and the other end of which is connected to the heat pump compressor. The second evaporator is connected in parallel with the first evaporator.
[0016] With the above-described structure, the second evaporator and the first evaporator are connected in parallel and can work together to cool the refrigerant in the heat pump system. The second evaporator can adjust according to the operating conditions of the first evaporator. While the first evaporator needs to cool the lubricating oil so that it can return to the oil tank, the second evaporator can assist in cooling the refrigerant in the heat pump system. The second evaporator removes the heat of condensation of the refrigerant in the heat pump system, further reducing the refrigerant temperature and thus benefiting the operation of the first evaporator.
[0017] Preferably, the lubricating oil control system of the screw compressor with heat pump system also includes a lubricating oil cooling system; wherein, the lubricating oil cooling system includes a second passage, which sequentially connects the screw compressor, the first evaporator and the oil tank in a circulating manner; the first evaporator is used to cool the lubricating oil flowing out of the screw compressor and send it back to the oil tank.
[0018] With the above-described structure, the temperature of the lubricating oil must not be too high during the operation of the screw compressor. Higher-temperature lubricating oil becomes more viscous, affecting its flowability within the bearings and increasing bearing wear. The second passage transports the lubricating oil from the screw compressor to the first evaporator, where it cools the lubricating oil in the oil-water separation system. The cooled lubricating oil has reduced viscosity, increased flowability, and returns to the oil tank for lubrication of the screw compressor.
[0019] Preferably, the lubricating oil control system of the screw compressor with heat pump system also includes a lubricating oil preheating system, which includes a screw compressor, a condenser and an oil tank; the condenser is used to heat the lubricating oil flowing out of the screw compressor and deliver it to the oil tank.
[0020] With the above-described structure, the lubricating oil temperature decreases when the weather gets cold. The lubricating oil becomes diluted due to the reduced temperature, decreasing its film thickness and rendering it ineffective for lubrication. The lubricating oil preheating system uses a condenser to heat the lubricating oil in the oil-water separation system. The heated lubricating oil is then returned directly to the oil tank without being flashed.
[0021] Preferably, the lubricating oil control system for the screw compressor with heat pump system further includes a first shut-off valve, a second shut-off valve, and a third shut-off valve; the first shut-off valve is disposed in the first passage, located between the screw compressor and the condenser, and is used to open or close the first passage; the second shut-off valve is disposed in the second passage, located between the screw compressor and the first evaporator, and is used to open or close the second passage; the third shut-off valve is disposed between the first evaporator and the flash evaporator, and is used to control the opening or closing of the passage between the flash evaporator and the first evaporator.
[0022] With the above-described structure, the first, second, and third shut-off valves are used to open or close their corresponding passages. By switching these three shut-off valves on and off, the connection and disconnection of different passages in the lubricating oil control system of the screw compressor containing the heat pump system can be achieved. Connecting different passages achieves different functional effects, thus enabling switching between several different operating modes. The lubricating oil control system of the screw compressor containing the heat pump system simultaneously satisfies the requirements for controlling the lubricating oil temperature, controlling the lubricating oil moisture content, and preheating the water in the water tank used for cooling the compression chamber.
[0023] Preferably, the lubricating oil control system for the screw compressor with heat pump system further includes a first oil pump and a second oil pump; the first oil pump is located between the oil tank and the screw compressor and is used to deliver the lubricating oil in the oil tank to the screw compressor; the second oil pump is located between the flash evaporator and the first evaporator and is used to extract the lubricating oil in the flash evaporator and deliver it to the first evaporator.
[0024] With the above-described structure, both the first and second oil pumps are installed in the oil-water separation system. Both pumps are used to extract lubricating oil, allowing it to flow rapidly within the oil-water separation system's piping. This increased lubricating oil flow rate also improves the operating speed of the oil-water separation system, thereby enhancing the efficiency of the lubricating oil control system for screw compressors containing heat pumps.
[0025] Preferably, the water supply system also includes a first solenoid valve, which is located between the water pump and the condenser, and is used to control the opening of the water supply system's piping.
[0026] Using the above-described structure, the first solenoid valve controls the opening degree of the pipes within the water supply system, thereby altering the water flow rate within the pipes. When the condenser in the heat pump system provides relatively little heat, reducing the opening degree slows the water flow, resulting in a more uniform and effective increase in water temperature within the pipes. When the condenser in the heat pump system can provide sufficient heat, increasing the opening degree allows more water to heat up.
[0027] Preferably, the heat pump system further includes a second solenoid valve and a third solenoid valve; the second solenoid valve is disposed between the second evaporator and the second expansion valve and is used to control the opening degree of the passage between the second expansion valve and the second evaporator; the third solenoid valve is disposed between the first evaporator and the second expansion valve and is used to control the opening degree of the passage between the second expansion valve and the first evaporator.
[0028] Using the above-described structure, the second and third solenoid valves are used to control the flow rate of refrigerant through the first and second evaporators in the heat pump system, respectively. In different operating modes of the screw compressor lubrication control system within the heat pump system, the cooling efficiency requirements of the first evaporator vary. By adjusting the opening degrees of the first and second solenoid valves, the operating efficiency of the first evaporator is altered. Simultaneously, the duration and efficiency of the second solenoid valve's action on the refrigerant are changed in different operating modes.
[0029] Preferably, the lubricating oil control system of the screw compressor with heat pump system also includes a moisture detector, which is used to detect the water content of the lubricating oil in the oil tank.
[0030] Using the above-described structure, the moisture detector can detect the water content of the lubricating oil in the tank in real time. When the water content of the lubricating oil in the tank is too high or too low, the lubricating oil is treated and adjusted by different operating modes of the screw compressor lubricating oil control system, which includes a heat pump system.
[0031] Preferably, the lubricating oil control system of the screw compressor with heat pump system also includes a thermometer, which is located between the first evaporator and the oil tank, and is used to detect the temperature of the lubricating oil after leaving the first evaporator.
[0032] With the above-described structure, all lubricating oil leaving the first evaporator returns to the oil tank. A thermometer detects whether the lubricating oil temperature reaches the specified level before entering the tank. Furthermore, based on the temperature of the lubricating oil leaving the first evaporator, the operating status of the heat pump system is adjusted, enabling the heat pump system to better provide heating and cooling for the lubricating oil control system.
[0033] Preferably, the lubricating oil control system of the screw compressor containing the heat pump system also includes a vacuum pump; the vacuum pump is connected to the water vapor outlet of the flash evaporator and is used for the flash evaporator to generate water vapor.
[0034] With the above-described structure, the vacuum pump creates a negative pressure environment inside the flash evaporator, causing the water in the lubricating oil to flash and form steam. The steam then exits from the top of the flash evaporator, achieving oil-water separation. The separated lubricating oil returns to the oil tank from the bottom of the flash evaporator and continues to be used for lubricating the screw compressor.
[0035] This application also provides a method for operating a screw compressor lubricating oil control system containing a heat pump system, which includes a screw compressor lubricating oil control system containing a heat pump system, and the method for operating the screw compressor lubricating oil control system containing a heat pump system includes:
[0036] The system detects the moisture content of the lubricating oil in the tank. When the moisture content of the lubricating oil in the tank is greater than 2%, it enters the water removal and heating mode. When the moisture content of the lubricating oil in the tank is less than 0.5%, it enters the cooling mode.
[0037] Water removal and heating mode: The heat pump system, oil-water separation system, and water replenishment system are activated. The lubricating oil flows in the first passage, while the second passage is closed. The heat pump system heats the condenser. The lubricating oil in the screw compressor enters the condenser through the first passage. The heated lubricating oil enters the flash evaporator for flash evaporation to separate the lubricating oil from the water. The water vapor after flash evaporation is discharged from the top of the flash evaporator. The lubricating oil is cooled by the first evaporator and returns to the oil tank. At the same time, the water in the water tank flows to the condenser for heating. The heated water flows to the screw compressor and is sprayed into the compression chamber of the screw compressor.
[0038] Cooling mode: The heat pump system, oil-water separation system, and water replenishment system are activated. The lubricating oil flows in the second passage. The pipeline between the screw compressor and the condenser is closed. The heat pump system heats the condenser. The lubricating oil in the screw compressor enters the first evaporator through the second passage for cooling. The heat of the lubricating oil is transferred to the heat pump system through the first evaporator. The cooled lubricating oil returns to the oil tank. At the same time, the water in the water tank flows to the condenser for heating. The heated water flows to the screw compressor and is sprayed into the compression chamber of the screw compressor.
[0039] Using the above method, by detecting the moisture content of the lubricating oil in the oil tank, the lubricating oil control system of the screw compressor containing the heat pump system can be determined to enter different working modes.
[0040] When the lubricating oil in the oil tank has an excessively high water content, the dewatering and heating mode allows the lubricating oil in the oil-water separation system to be heated by the heat pump system. The heated lubricating oil then undergoes flash evaporation, separating the excess water as steam, which is then discharged from the flash evaporator. In this dewatering and heating mode, the water in the tank also flows through pipes to the condenser. The condenser heats both the lubricating oil and the water simultaneously. This heated water is then used to cool the compression chamber of the screw compressor, preventing condensation due to excessively low water temperature. Using this method, the water content of the lubricating oil in the oil tank is reduced while the water used for cooling is heated to meet the operating requirements of the compression chamber.
[0041] When the water content of the lubricating oil in the oil tank is too low, the cooling mode is activated. The lubricating oil in the screw compressor is transported to the first evaporator, where it is cooled. The lubricating oil does not pass through the condenser during its movement, thus avoiding the condenser heating the lubricating oil. The cooled lubricating oil has a lower viscosity and a higher water content. At this time, the water in the water tank passes through the condenser, where it is heated. The heated water can be used to cool the compression chamber. Therefore, in cooling mode, the lubricating oil is cooled while the cooling water is heated to the operating temperature.
[0042] Preferably, the operating method of the lubricating oil control system for a screw compressor with a heat pump system further includes: Lubricating oil heating mode: the heat pump system, oil-water separation system, and water replenishment system are activated, the lubricating oil flows in the first passage, and the second passage is closed. The heat pump system heats the condenser. The lubricating oil in the screw compressor enters the condenser through the first passage. After being heated in the condenser, the lubricating oil returns to the oil tank via the non-activated flash evaporator and first evaporator. Simultaneously, water in the water tank flows to the condenser for heating, and the heated water flows to the screw compressor and is sprayed into the compression chamber of the screw compressor.
[0043] Using the above method, the heat pump system heats the lubricating oil through the condenser, ensuring it reaches operating temperature even in cold environments. The heated lubricating oil passes through a flash evaporator without flashing, and the first evaporator remains inactive to prevent cooling. The lubricating oil returns to the oil tank after passing through the first evaporator, where it is used to lubricate the screw compressor. Simultaneously, water in the water tank flows to the condenser for heating, simultaneously heating the water and the lubricating oil. The heated water, reaching the designated operating temperature, enters the compression chamber for cooling.
[0044] Compared with the prior art, the beneficial effects of this application are as follows:
[0045] The lubricating oil control system for a screw compressor with a heat pump system in this application can evaporate the moisture in the lubricating oil when the moisture content in the oil tank is high, thereby reducing the moisture content of the lubricating oil. When the moisture content of the lubricating oil is too low, the system's pathway is modified to increase the moisture content of the lubricating oil in the oil tank to bring it to operating temperature. When the temperature of the lubricating oil in the oil tank is low in winter, the lubricating oil system can preheat the lubricating oil in the oil tank, thereby bringing the lubricating oil to operating temperature. The screw compressor's compression chamber requires water for cooling during operation, and the water used for cooling needs to be preheated to prevent condensation in the compression chamber due to excessively low temperature. During the mode switching process of the lubricating oil control system for the screw compressor with a heat pump system, the condenser can heat the water in the water tank, so that the heated water can be used to cool the compression chamber of the screw compressor. Attached Figure Description
[0046] This application can be better understood by describing its embodiments in conjunction with the accompanying drawings, in which:
[0047] Figure 1 This is a schematic diagram of an embodiment of a screw compressor lubricating oil control system containing a heat pump system according to the present invention;
[0048] Figure 2 This is a flowchart illustrating the working method of a screw compressor lubricating oil control system containing a heat pump system according to the present invention.
[0049] In the above figures, the meanings of the reference numerals are as follows:
[0050] Screw compressor 1
[0051] Heat pump compressor 2
[0052] Condenser 3
[0053] Second evaporator 4
[0054] First Evaporator 5
[0055] Flash evaporator 6
[0056] Moisture analyzer 7
[0057] Fuel tank 8
[0058] First oil pump 9
[0059] Exhaust side bearing 10
[0060] intake side bearing 11
[0061] Water tank 12
[0062] Water pump 13
[0063] First solenoid valve 14
[0064] First shut-off valve 15
[0065] Second shut-off valve 16
[0066] Vacuum pump 17
[0067] Second oil pump 18
[0068] First expansion valve 19
[0069] Second solenoid valve 20
[0070] Third solenoid valve 21
[0071] Thermometer 22
[0072] Second expansion valve 23
[0073] Water vapor thermometer 24
[0074] Third shut-off valve 25 Detailed Implementation
[0075] Unless otherwise defined, the technical or scientific terms used in this specification and claims shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.
[0076] All the values listed in this article, ranging from the lowest to the highest, refer to all values obtained by incrementing the lowest and highest values by one unit when the difference between the lowest and highest values is more than two units.
[0077] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0078] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0079] like Figure 1As shown, this embodiment discloses a screw compressor lubricating oil control system with a heat pump system, which includes a heat pump system, an oil-water separation system, and a water replenishment system. The heat pump system includes a heat pump compressor 2, a condenser 3, a second expansion valve 23, and a first evaporator 5, all connected in a circulating manner. The condenser 3 is used to cool the refrigerant flowing in the heat pump system, and the first evaporator 5 is used to heat the refrigerant in the heat pump circulation system. The oil-water separation system includes an oil tank 8, a screw compressor 1, a condenser 3, a first expansion valve 19, a flash evaporator 6, and a first evaporator 5, all connected in a circulating manner via a first passage. The condenser 3 is used to heat the lubricating oil discharged from the screw compressor 1, the flash evaporator 6 flashes the heated lubricating oil to evaporate and discharge the water in the lubricating oil, and the first evaporator 5 cools the flashed lubricating oil to the temperature required to enter the oil tank 8. The water replenishment system includes a water tank 12, a condenser 3, and a screw compressor 1 connected in sequence. The condenser 3 heats the water from the water tank 12, and the heated water is delivered to the compression chamber of the screw compressor 1. The lubricating oil control system for the screw compressor with a heat pump system also includes a first oil pump 9 and a second oil pump 18. The first oil pump 9 is located between the oil tank 8 and the screw compressor 1, and is used to deliver the lubricating oil in the oil tank 8 to the screw compressor 1. The second oil pump 18 is located between the flash evaporator 6 and the first evaporator 5, and is used to extract the lubricating oil in the flash evaporator 6 and deliver it to the first evaporator 5. The water replenishment system also includes a water pump 13, which is located between the water tank 12 and the condenser 3, and is used to extract water from the water tank 12 and send it into the condenser 3.
[0080] In this embodiment, the oil tank 8 supplies lubricating oil to the screw compressor 1 via the first oil pump 9. The lubricating oil has a circulation flow rate of 1200 kg / hr, an absolute pressure of 2 Bar, and a temperature of less than 45°C. The lubricating oil from the outlets of the suction-side bearing 11 and the discharge-side bearing 10 of the screw compressor 1 enters the condenser 3 through the cold flow inlet b1. The lubricating oil is heated in the condenser 3 by a heat pump system. After heat exchange, the lubricating oil flows out through the cold flow outlet b2 and enters the flash evaporator 6 through the first expansion valve 19. The lubricating oil undergoes flash evaporation in the flash evaporator to achieve oil-water separation. The water vapor is discharged from the top of the flash evaporator 6 through the vacuum pump 17. The lubricating oil in the flash evaporator 6 is pumped by the second oil pump 18 and enters the hot flow inlet e1 of the first evaporator 5. The lubricating oil is cooled in the first evaporator 5 and flows out through the hot flow outlet e2 of the first evaporator 5, entering the oil tank 8.
[0081] In this embodiment, the heat pump system also includes a second evaporator 4. One end of the second evaporator 4 is connected to the condenser 3, and the other end is connected to the heat pump compressor 2. The second evaporator 4 is connected in parallel with the first evaporator 5. The heat pump system uses R134a as the refrigerant and employs a variable frequency compressor. The refrigerant flow rate is 0.6 kg / s. When the suction pressure is 8 Bar and the discharge pressure is 33 Bar, the maximum heating capacity of the system is 58 kW. The low-temperature, low-pressure refrigerant is pressurized by the heat pump compressor 2 and enters the hot flow inlet a1 of the condenser 3. After heat exchange, it flows out from the hot flow outlet a2. After being depressurized by the second expansion valve 23, one path passes through the second solenoid valve 20 and enters the second evaporator 4 and then the suction port of the heat pump compressor 2. The other path passes through the third solenoid valve 21 and enters the cold flow inlet d1 of the first evaporator 5. After heat exchange, it flows out from the cold flow outlet d2 and then into the suction port of the heat pump compressor 2.
[0082] Simultaneously, the water replenishment system is activated. Water from water tank 12 flows out and is compressed by water pump 13 before entering the cold flow inlet c1 of condenser 3. The mass flow rate of water in the replenishment system is 400 kg / hr, and the outlet pressure of water pump 13 is 2 Bar. After heat exchange, the water flows out from the cold flow outlet c2 of condenser 3. The heated water enters the compression chamber of screw compressor 1 along the path of the replenishment system. The heated water can cool the compression chamber when screw compressor 1 is working, preventing condensation from forming in the compression chamber due to excessively cold water. Water pump 13 effectively increases the flow rate of water in the replenishment system, thereby improving working efficiency.
[0083] like Figure 1 As shown, in this embodiment, the lubricating oil control system of the screw compressor with heat pump system also includes a lubricating oil cooling system; wherein, the lubricating oil cooling system includes a second passage, which sequentially connects the screw compressor 1, the first evaporator 5 and the oil tank 8 in a circulating manner; the first evaporator 5 is used to cool down the lubricating oil flowing out of the screw compressor 1 and send it back to the oil tank 8.
[0084] The lubricating oil from the outlets of the suction-side bearing 11 and the discharge-side bearing 10 of the screw compressor 1 enters the second passage. The lubricating oil enters the first evaporator 5 from the hot flow inlet e1. The first evaporator 5 can cool the lubricating oil, and the lubricating oil after heat exchange flows out from the hot flow outlet e2 of the first evaporator 5 back to the oil tank 8.
[0085] like Figure 1As shown, in this embodiment, the lubricating oil control system for the screw compressor with a heat pump system further includes a first shut-off valve 15, a second shut-off valve 16, and a third shut-off valve 25. The first shut-off valve 15 is disposed in the first passage, located between the screw compressor 1 and the condenser 3, and is used to open or close the first passage. The second shut-off valve 16 is disposed in the second passage, located between the screw compressor 1 and the first evaporator 5, and is used to open or close the second passage. The third shut-off valve 25 is disposed between the first evaporator 5 and the flash evaporator 6, and is used to control the opening or closing of the passage between the flash evaporator 6 and the first evaporator 5. Furthermore, the lubricating oil control system for the screw compressor with a heat pump system also includes a first solenoid valve 14 disposed between the water pump 13 and the condenser 3, and is used to control the opening degree of the water supply system pipeline. A second solenoid valve 20 is disposed between the second evaporator 4 and the second expansion valve 23, and is used to control the opening degree of the passage between the second expansion valve 23 and the second evaporator 4. A third solenoid valve 21 is disposed between the first evaporator 5 and the second expansion valve 23, and is used to control the opening degree of the passage between the second expansion valve 23 and the first evaporator 5.
[0086] In this application, the lubricating oil control system for a screw compressor containing a heat pump system has three operating modes:
[0087] When the moisture content in oil tank 8 exceeds 2%, the second shut-off valve 16 closes, preventing lubricating oil from entering the second passage. The first shut-off valve 15 opens, and the third shut-off valve 25 opens, allowing the heat pump compressor 2 to operate at maximum power (25kW, 58kW heating capacity). The heat pump compression system transfers the generated heat to the lubricating oil and water through the condenser. Water in water tank 12 is pressurized by water pump 13 and pumped into condenser 3. The first solenoid valve 14 adjusts the water flow rate to 400kg / hr. The water absorbs heat in condenser 3, raising its temperature to 90℃, resulting in a heat flow of 30.6kW. The lubricating oil at the outlets of the suction-side bearing 11 and discharge-side bearing 10 of screw compressor 1 has a flow rate of 1200kg / hr, an absolute pressure of 2Bar, and a temperature of 65℃. The lubricating oil passes through the first passage, through the first shut-off valve 15, and enters the cold flow inlet b1 of condenser 3. The lubricating oil absorbs heat energy from the heat pump system in the condenser and is heated to 98°C, then flows out from the cold flow outlet b2 with a heat flow rate of 27.4 kW. After being heated, the high-temperature lubricating oil is depressurized by the first expansion valve 19 and enters the flash evaporator 6. Due to the suction effect of the vacuum pump 17, the flash evaporator 6 is under negative pressure, and the water in the lubricating oil begins to flash into water vapor under this negative pressure. The water vapor is discharged from the top of the flash evaporator 6 through the vacuum pump 17. The water vapor thermometer 24 is electrically connected to the first solenoid valve 14. When the temperature detected by the water vapor thermometer 24 is high, the opening of the first solenoid valve 14 is increased, allowing more water to enter the screw compressor 1. More water helps lower the temperature inside the compression chamber. The lubricating oil in the flash evaporator 6 is pumped into the hot flow inlet e1 of the first evaporator 5 by the second oil pump 18, cooled to 42°C, and then flows out from the hot flow outlet e2 of the first evaporator 5 with a heat flow rate of 35.4 kW. The lubricating oil leaving the first evaporator 5 enters the oil tank 8. This process, based on water preheating, evaporates 15 kg / hr of water from the lubricating oil.
[0088] When the moisture content in oil tank 8 is less than 0.5%, the second shut-off valve 16 opens, simultaneously opening the second passage, allowing lubricating oil to enter. The first shut-off valve 15 closes, and the third shut-off valve 25 closes, preventing lubricating oil from passing through condenser 3. At this time, since there is no need to heat the lubricating oil, only preheating of the water in water tank 8 is required. The heat pump compressor 2 operates at low power, with a compressor power of 13kW and a heating capacity of 30.6kW. The water in water tank 12 is pressurized by water pump 13 and pumped into condenser 3. The solenoid valve 14 adjusts the water flow rate to 400kg / hr. The water absorbs heat in condenser 3 and heats up to 90℃, with a heat flow rate of 30.6kW. The lubricating oil at the outlet of the suction side bearing 11 and the discharge side bearing 10 of screw compressor 1 has a flow rate of 1200kg / hr, an absolute pressure of 2Bar, and a temperature of 65℃. The lubricating oil passes through the second shut-off valve 16 and enters the hot flow inlet e1 of the first evaporator 5, where it undergoes heat exchange. The lubricating oil cools to 41°C and flows out from the hot flow outlet e2 of the second evaporator 5, with a heat flow rate of 18.9 kW. The cooled lubricating oil flows back into the oil tank 8. When the thermometer 22 detects a temperature greater than 45°C, the opening of the third solenoid valve 21 is increased, increasing the amount of refrigerant entering the first evaporator 5 and thus increasing its cooling capacity. Simultaneously, the opening of the second solenoid valve 20 is decreased, reducing the cooling capacity of the second evaporator 4 so that more refrigerant can serve the first evaporator 5. When the thermometer 22 detects a temperature less than 35°C, the opening of the second solenoid valve 20 is increased, increasing the refrigerant flow into the second evaporator 4 and thus increasing its cooling capacity. Simultaneously, the opening of the third solenoid valve 21 is decreased, reducing the cooling capacity of the second evaporator 5, allowing the refrigerant in the heat pump system to maximize its cooling effect. This workflow, while meeting the requirement of water preheating, can maintain the lubricating oil temperature at 40°C.
[0089] When the lubricating oil temperature is low in winter, the heat pump system starts before the screw compressor 1 starts. Heat is supplied to the lubricating oil through the condenser to preheat it. The second shut-off valve 16 is closed, preventing lubricating oil from entering the second passage. The first shut-off valve 15 is open, the second solenoid valve 20 is open, and the third solenoid valve 21 is closed. The lubricating oil from the outlets of the suction-side bearing 11 and the discharge-side bearing 10 of the screw compressor 1 passes through the first shut-off valve 15 and enters the cold flow inlet b1 of the condenser 3, where heat transfer within the condenser 3 raises the lubricating oil temperature. After heating, the lubricating oil flows out from the cold flow outlet b2 and enters the flash evaporator 6 through the first expansion valve 19. Since flash evaporation is not required for lubricating oil preheating, the first expansion valve 19 is at its maximum opening at this time. The vacuum pump 17 is not started, so there is no need to create a negative pressure within the flash evaporator 6. The lubricating oil in the flash evaporator 6 leaves the flash evaporator 6 under the action of the second oil pump 18 and enters the first evaporator 5 through the hot flow inlet e1. The first evaporator 5 does not cool the lubricating oil. The lubricating oil flows out from the hot flow outlet e2 of the first evaporator 5 and enters the oil tank 8. This process can preheat the lubricating oil to 40°C.
[0090] like Figure 1 As shown, in this embodiment, the lubricating oil control system for the screw compressor with a heat pump system also includes a moisture detector 7, which is used to detect the water content of the lubricating oil in the oil tank 8. The moisture detector 7 can detect the water content of the lubricating oil in the oil tank 8 in real time. When there is too much water in the lubricating oil in the oil tank 8, the lubricating oil is treated and adjusted through different working modes of the lubricating oil control system for the screw compressor with a heat pump system.
[0091] like Figure 2 As shown in the figure, this embodiment also discloses a method for operating a screw compressor lubricating oil control system containing a heat pump system, which includes a screw compressor lubricating oil control system containing a heat pump system. The method for operating the screw compressor lubricating oil control system containing a heat pump system includes:
[0092] S1. Detect the moisture content of the lubricating oil in oil tank 8. When the moisture content of the lubricating oil in oil tank 8 is greater than 2%, enter the water removal and heating mode.
[0093] S2, Dewatering and Heating Mode: The heat pump system, oil-water separation system, and water replenishment system are activated. The lubricating oil flows in the first passage, and the second passage is closed. The heat pump system heats the condenser 3. The lubricating oil in the screw compressor 1 enters the condenser 3 through the first passage. The heated lubricating oil enters the flash evaporator 6 for flash evaporation to separate the lubricating oil from the water. The water vapor after flash evaporation is discharged from the top of the flash evaporator 6. The lubricating oil is cooled by the first evaporator 5 and returns to the oil tank 8. At the same time, the water in the water tank 12 flows to the condenser 3 for heating. The heated water flows to the screw compressor 1 and is sprayed into the compression chamber of the screw compressor 1.
[0094] S3, Cooling Mode: The heat pump system, oil-water separation system, and water replenishment system are activated. The lubricating oil flows in the second passage. The pipeline between the screw compressor 1 and the condenser 3 is closed. The heat pump system heats the condenser 3. The lubricating oil in the screw compressor 1 enters the first evaporator 5 through the second passage for cooling. The heat of the lubricating oil is transferred to the heat pump system through the first evaporator 5. The cooled lubricating oil returns to the oil tank 8. At the same time, the water in the water tank 12 flows to the condenser 3 for heating. The heated water flows to the screw compressor 1 and is sprayed into the compression chamber of the screw compressor 1.
[0095] By detecting the moisture content of the lubricating oil in oil tank 8, the lubricating oil control system of the screw compressor with heat pump system is determined to enter different operating modes. When the moisture content of the lubricating oil in oil tank 8 is too high (greater than 2%), step S2 is used. The dehydration and heating mode allows the lubricating oil in the oil-water separation system to be heated under the action of the heat pump system. The heated lubricating oil can then undergo flash evaporation, and the excess water is separated into water vapor and discharged from the flash evaporator 6. In the above dehydration and heating mode, the water in water tank 12 flows to the condenser 3 through the pipeline. The condenser 3 heats the water while simultaneously heating the lubricating oil. The heated water meets the temperature requirements for cooling the compression chamber of the screw compressor 1, preventing condensation in the compression chamber due to excessively low water temperature. Using this method, the moisture content of the lubricating oil in oil tank 8 is reduced, and the water used for cooling is heated to meet the usage requirements of the compression chamber.
[0096] When the water content of the lubricating oil in oil tank 8 is too low, below 0.5%, step S3 is used. The lubricating oil in screw compressor 1 is transported to the first evaporator 5, where it is cooled. The lubricating oil does not pass through condenser 3 during its movement, thus avoiding the condenser 3 heating the lubricating oil. Meanwhile, the water in water tank 12 passes through condenser 3, where it is heated. The heated water is used to cool the compression chamber. Therefore, in cooling mode, the lubricating oil is cooled simultaneously while the cooling water is heated to the operating temperature.
[0097] In this embodiment, the operating method of the lubricating oil control system for a screw compressor with a heat pump system further includes: Lubricating oil heating mode: The heat pump system, oil-water separation system, and water replenishment system are activated. The lubricating oil flows in the first passage, the second passage is closed, and the heat pump system heats the condenser 3. The lubricating oil in the screw compressor 1 enters the condenser 3 through the first passage. After being heated in the condenser 3, the lubricating oil returns to the oil tank 8 via the non-activated flash evaporator 6 and the first evaporator 5. Simultaneously, water in the water tank 12 flows to the condenser 3 for heating, and the heated water flows to the screw compressor 1 and is sprayed into the compression chamber of the screw compressor 1. The heat pump system heats the lubricating oil through the condenser 3, ensuring that the lubricating oil reaches its operating temperature even in cold environments. The heated lubricating oil does not flash through the flash evaporator 6, and the first evaporator 5 remains inactive to prevent the lubricating oil from cooling down. The lubricating oil that has passed through the first evaporator 5 returns to the oil tank 8 for lubrication of the screw compressor 1. Meanwhile, the water in water tank 12 flows into condenser 3 for heating. Condenser 3 heats the lubricating oil while simultaneously heating the water. Once the heated water reaches the designated operating temperature, it enters the compression chamber for cooling.
[0098] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. 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 lubricating oil control system for a screw compressor including a heat pump system, characterized in that, This includes a heat pump system, an oil-water separation system, a water replenishment system, and a lubricating oil cooling system; The heat pump system includes a heat pump compressor, a condenser, a second expansion valve, and a first evaporator that are connected in a cycle. The condenser is used to cool the refrigerant flowing in the heat pump system, and the first evaporator is used to heat the refrigerant in the heat pump cycle system. The oil-water separation system includes an oil tank, a screw compressor, a condenser, a first expansion valve, a flash evaporator, and a first evaporator, all connected by a first circulating passage. The condenser heats the lubricating oil discharged from the screw compressor. The water vapor outlet of the flash evaporator is connected to a vacuum pump to discharge the water vapor generated during flash evaporation and to maintain a negative pressure inside the flash evaporator. This allows the heated lubricating oil to be flashed, evaporating and discharging the water in the lubricating oil. The first evaporator cools the flashed lubricating oil to the temperature required to enter the oil tank. The lubricating oil cooling system includes a second passage that sequentially connects the screw compressor, the first evaporator, and the oil tank; the first evaporator is used to cool the lubricating oil flowing out of the screw compressor and then return it to the oil tank. The water replenishment system is used to replenish water to the screw compressor and includes a water tank, a condenser and a screw compressor connected in sequence. The condenser is used to heat the water from the water tank and the heated water is delivered to the compression chamber of the screw compressor.
2. The screw compressor lubricating oil control system with a heat pump system as described in claim 1, characterized in that, The water replenishment system also includes a water pump, which is located between the water tank and the condenser, and is used to draw water from the water tank and send it into the condenser.
3. The screw compressor lubricating oil control system with a heat pump system as described in claim 1, characterized in that, The heat pump system is also equipped with a second evaporator, one end of which is connected to the condenser and the other end of which is connected to the heat pump compressor. The second evaporator is connected in parallel with the first evaporator.
4. The screw compressor lubricating oil control system with a heat pump system as described in claim 1, characterized in that, The screw compressor lubricating oil control system with heat pump system also includes a lubricating oil preheating system, which includes the screw compressor, the condenser and the oil tank; the condenser is used to heat the lubricating oil flowing out of the screw compressor and deliver it to the oil tank.
5. The screw compressor lubricating oil control system with a heat pump system as described in claim 1, characterized in that, The lubricating oil control system of the screw compressor containing the heat pump system also includes a first shut-off valve, a second shut-off valve and a third shut-off valve. The first shut-off valve is installed on the first passage, located between the screw compressor and the condenser, and is used to open or close the first passage. The second shut-off valve is installed on the second passage, located between the screw compressor and the first evaporator, and is used to open or close the second passage; The third shut-off valve is located between the first evaporator and the flash evaporator, and is used to control the opening or closing of the passage between the flash evaporator and the first evaporator.
6. The screw compressor lubricating oil control system with a heat pump system as described in claim 1, characterized in that, The lubricating oil control system for the screw compressor containing the heat pump system also includes a first oil pump and a second oil pump; The first oil pump is disposed between the oil tank and the screw compressor, and is used to deliver the lubricating oil in the oil tank to the screw compressor; The second oil pump is located between the flash evaporator and the first evaporator, and is used to extract the lubricating oil in the flash evaporator and deliver it to the first evaporator.
7. The screw compressor lubricating oil control system with a heat pump system as described in claim 2, characterized in that, The water replenishment system also includes a first solenoid valve, which is disposed between the water pump and the condenser and is used to control the opening degree of the pipeline of the water replenishment system.
8. The screw compressor lubricating oil control system with a heat pump system as described in claim 3, characterized in that, The heat pump system also includes a second solenoid valve and a third solenoid valve; The second solenoid valve is disposed between the second evaporator and the second expansion valve, and is used to control the opening degree of the passage between the second expansion valve and the second evaporator; The third solenoid valve is located between the first evaporator and the second expansion valve, and is used to control the opening degree of the passage between the second expansion valve and the first evaporator.
9. The lubricating oil control system for a screw compressor with a heat pump system as described in any one of claims 1-3, characterized in that, The screw compressor lubricating oil control system with heat pump system also includes a moisture detector, which is used to detect the water content of the lubricating oil in the oil tank.
10. The lubricating oil control system for a screw compressor with a heat pump system as described in any one of claims 1-3, characterized in that, The lubricating oil control system of the screw compressor with heat pump system also includes a thermometer, which is installed between the first evaporator and the oil tank to detect the temperature of the lubricating oil after it leaves the first evaporator.
11. A method for operating a lubricating oil control system for a screw compressor containing a heat pump system as described in any one of claims 1-10, characterized in that, The operating method of the lubricating oil control system for the screw compressor containing a heat pump system includes: The moisture content of the lubricating oil in the oil tank is detected. When the moisture content of the lubricating oil in the oil tank is greater than 2%, the dehydration and heating mode is activated. Water removal and heating mode: The heat pump system, the oil-water separation system, and the water replenishment system are activated. The lubricating oil flows in the first passage, the second passage is closed, the heat pump system heats the condenser, and the lubricating oil in the screw compressor enters the condenser through the first passage. The heated lubricating oil enters the flash evaporator for flash evaporation to separate the lubricating oil from the water. The water vapor after flash evaporation is discharged from the top of the flash evaporator, and the lubricating oil returns to the oil tank after being cooled by the first evaporator. At the same time, the water in the water tank flows to the condenser for heating, and the heated water flows to the screw compressor and is sprayed into the compression chamber of the screw compressor. Cooling mode: The heat pump system, the oil-water separation system, and the water replenishment system are activated. The lubricating oil flows in the second passage. The pipeline between the screw compressor and the condenser is closed. The heat pump system heats the condenser. The lubricating oil in the screw compressor enters the first evaporator through the second passage for cooling. The heat of the lubricating oil is transferred to the heat pump system through the first evaporator. The cooled lubricating oil returns to the oil tank. At the same time, the water in the water tank flows to the condenser for heating. The heated water flows to the screw compressor and is sprayed into the compression chamber of the screw compressor.
12. The operating method of the lubricating oil control system for a screw compressor containing a heat pump system as described in claim 11, characterized in that, The operating method of the screw compressor lubricating oil control system containing the heat pump system also includes: Lubricating oil heating mode: The heat pump system, the oil-water separation system, and the water replenishment system are started. The lubricating oil flows in the first passage, the second passage is closed, the heat pump system heats the condenser, and the lubricating oil in the screw compressor enters the condenser through the first passage. After the lubricating oil is heated in the condenser, it returns to the oil tank through the flash evaporator and the first evaporator, which are not started. At the same time, the water in the water tank flows to the condenser for heating, and the heated water flows to the screw compressor and is sprayed into the compression chamber of the screw compressor.