Refrigerating unit lubricating oil waste heat recovery system

Abstract

The invention relates to the technical field of waste heat recovery, in particular to a refrigerating unit lubricating oil waste heat recovery system which comprises an oil cooler provided with a first hot oil inlet pipe and a first hot oil outlet pipe. The oil heat recoverer is provided with a second hot oil inlet pipe, a second hot oil outlet pipe, a side water inlet pipe and a side water outlet pipe. The heat dissipation load of the evaporative condenser can be reduced by recycling waste heat of lubricating oil, the running time of a condenser heat dissipation fan is shortened, indirect heat exchange is conducted between water used in the water tank and the ammonia gas heat recoverer and between the water used in the water tank and the oil heat recoverer through the second-stage heat exchanger, and pollution caused by leakage of ammonia gas to water stored in the water tank can be effectively avoided; meanwhile, a circulating water pipeline between the secondary heat exchanger and the heat recoverer is closed circulation, pure water is injected into the pipeline, scaling of the heat exchanger can be completely eradicated, and it is ensured that the heat exchanger achieves the optimal heat exchange effect.

Description

Technical Field

[0001] The invention relates to the technical field of waste heat recovery, and in particular to a refrigeration unit lubricating oil waste heat recovery system. Background Art

[0002] Screw compressors require lubricating oil to lubricate the operation of the screw rotor and seal the gap between the rotors. Oil pressure is also needed to load and unload the compressor. The temperature of the lubricating oil in the rotor working volume rises due to heat, and it needs to be cooled and filtered before reuse. The cooling of the lubricating oil is very important for the operation of the screw compressor.

[0003] At present, the main oil cooling method is to use a heat exchanger to cool the lubricating oil, especially the most common method of cooling the lubricating oil by using the refrigerant liquid condensed by the evaporative condenser to enter the oil cooler. Under the conditions of evaporation temperature -30℃ and condensation temperature 35℃, the heat discharged by the oil cooler accounts for 20% of the total heat dissipation of the refrigeration unit. The lower the evaporation temperature, the higher the heat discharged by the oil cooler. It can be seen that the heat dissipation of the oil cooler accounts for a considerable proportion of the heat dissipation load of the entire refrigeration system. The lubricating oil contains a large amount of heat, which is not only not utilized, but also increases the heat dissipation load of the refrigeration system, which is not conducive to energy saving and consumption reduction. In addition, the outer wall of the existing evaporative condenser heat exchange tube is severely scaled, resulting in the heat dissipation far below the rated value, especially in the summer when the refrigeration unit is running under high pressure for a long time in high temperature and high humidity weather. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of high energy consumption caused by large amount of heat loss of lubricating oil of refrigerating unit in the prior art, and to propose a waste heat recovery system for lubricating oil of refrigerating unit.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A refrigeration unit lubricating oil waste heat recovery system includes an oil cooler, the oil cooler is provided with a first hot oil inlet pipe and a first hot oil outlet pipe, and further includes: An oil heat recovery device, wherein the oil heat recovery device is provided with a second hot oil inlet pipe, a second hot oil outlet pipe, a side water inlet pipe, and a side water outlet pipe, and the oil heat recovery device is connected to the first hot oil inlet pipe on the oil cooler through the second hot oil outlet pipe; An oil pump, wherein the oil pump is provided with a first inlet and a first outlet; A high-temperature circulation pump, wherein the high-temperature circulation pump is provided with a second inlet and a second outlet, and the high-temperature circulation pump is connected to a side water outlet pipe on the oil heat recovery device through the second inlet; A plate heat exchanger, wherein the plate heat exchanger is provided with a high temperature side inlet, a high temperature side outlet, a side water inlet, a low temperature inlet, and a low temperature outlet. The plate heat exchanger is connected to the second outlet of the high temperature circulation pump through the high temperature side inlet, and the plate heat exchanger is connected to the side water inlet of the oil heat recovery device through the high temperature side outlet; A screw compressor, wherein the screw compressor is provided with an exhaust pipe and an oil return pipe, and the screw compressor is connected to a first outlet of an oil pump; An oil filter, the oil filter is used to connect the first hot oil outlet pipe of the oil cooler and the first outlet of the oil pump; An oil separator, the oil separator is connected to the exhaust pipe on the screw compressor, the oil separator is provided with a third hot oil outlet pipe, and the oil separator is connected to the oil heat recovery device through the third hot oil outlet pipe and the second hot oil inlet pipe; A low-temperature circulation pump, wherein the low-temperature circulation pump is provided with a third inlet and a third outlet, and the low-temperature circulation pump is connected to the low-temperature inlet of the plate heat exchanger through the third outlet; A water tank, wherein a fourth inlet and a fourth outlet are provided on the water tank, the water tank is connected to the low-temperature outlet on the plate heat exchanger through the fourth inlet, and the water tank is connected to the third inlet on the low-temperature circulation pump through the fourth outlet; A liquid level sensor is installed on the water tank.

[0006] Preferably, an oil temperature sensor is installed on the second hot oil outlet of the oil heat recovery device, and an electric three-way valve is installed on the side water inlet pipe of the oil heat recovery device.

[0007] Preferably, a direct discharge stop valve and a heat recovery stop valve are installed on the third hot oil outlet pipe of the oil separator.

[0008] Preferably, the high-temperature circulation pump is located between the oil heat recovery device and the plate heat exchanger, and the high-temperature circulation pump connects the oil heat recovery device and the plate heat exchanger through a first pipeline.

[0009] Preferably, the low-temperature circulation pump is located between the plate heat exchanger and the water tank, and the low-temperature circulation pump is connected to the plate heat exchanger and the water tank through a second pipeline.

[0010] Preferably, an electric regulating valve cooperating with a liquid level sensor is installed on the fourth inlet of the water tank.

[0011] Preferably, the electric regulating valve is equipped with a PID regulating module.

[0012] Compared with the prior art, the present invention has the following advantages: 1. The present invention can reduce the heat dissipation load of the evaporative condenser by recycling the waste heat of the lubricating oil, reduce the operating time of the condenser heat dissipation fan, and reduce the operating cost.

[0013] 2. The present invention can significantly reduce the operating condensing pressure of the refrigeration unit while reducing the heat dissipation load of the evaporative condenser through waste heat recovery, thereby improving the operating efficiency of the refrigeration unit and reducing operating energy consumption.

[0014] 3. The present invention recovers the heat in the lubricating oil through waste heat recovery, which is used for heating process production water, reducing the energy consumption of steam, natural gas, electricity, etc., and achieving the purpose of energy saving and consumption reduction.

[0015] 4. In the present invention, the water used in the water tank is indirectly exchanged with the ammonia heat recovery device and the oil heat recovery device through a secondary heat exchanger, which can effectively avoid the pollution of the water stored in the water tank caused by ammonia leakage. At the same time, the circulating water pipeline between the secondary heat exchanger and the heat recovery device is a closed loop, and the pipeline is filled with pure water, which can completely prevent the scaling of the heat exchanger and ensure that the heat exchanger achieves the best heat exchange effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural schematic diagram of a refrigeration unit lubricating oil waste heat recovery system proposed by the present invention; Figure 2 This is a process flow chart for using an oil separator in a refrigeration unit lubricating oil waste heat recovery system proposed by the present invention.

[0017] In the figure: 1. Oil cooler; 2. Oil heat recovery device; 3. Oil pump; 4. High-temperature circulation pump; 5. Plate heat exchanger; 6. Oil temperature sensor; 7. Electric three-way valve; 8. Screw compressor; 9. Oil filter; 10. Oil separator; 11. Low-temperature circulation pump; 12. Water tank; 13. Direct discharge stop valve; 14. Heat recovery stop valve; 15. Electric regulating valve; 16. Liquid level sensor. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0019] Reference Figure 1-Figure 2 A refrigeration unit lubricating oil waste heat recovery system includes an oil cooler 1, on which a first hot oil inlet pipe and a first hot oil outlet pipe are provided, and also includes an oil heat recovery device 2, an oil pump 3, a high-temperature circulation pump 4, a plate heat exchanger 5, a screw compressor 8, an oil filter 9, an oil separator 10, a low-temperature circulation pump 11, a water tank 12, and a liquid level sensor 16. It should be noted that by setting up this system, on the one hand, the heat dissipation load of the evaporative condenser can be reduced, the operating time of the condenser cooling fan can be reduced, and the operating cost can be reduced; on the other hand, the heat in the lubricating oil can be recovered through waste heat recovery and used for heating process production water, thereby reducing the energy consumption of steam, natural gas, electricity and other energy sources, thereby achieving the purpose of energy saving.

[0020] The oil heat recovery device 2 is provided with a second hot oil inlet pipe, a second hot oil outlet pipe, a side water inlet pipe, and a side water outlet pipe, and the oil heat recovery device 2 is connected to the first hot oil inlet pipe on the oil cooler 1 through the second hot oil outlet pipe, and the high-temperature circulating water is heated by the oil heat recovery device 2. The high-temperature circulating water is provided with a second inlet and a second outlet, and the high-temperature circulating pump 4 is connected to the side water outlet pipe on the oil heat recovery device 2 through the second inlet.

[0021] The oil pump 3 is provided with a first inlet and a first outlet, the screw compressor 8 is provided with an exhaust pipe and an oil return pipe, the screw compressor 8 is connected to the first outlet of the oil pump 3, and the oil filter 9 is used to connect the first hot oil outlet pipe of the oil cooler 1 and the first outlet of the oil pump 3.

[0022] The plate heat exchanger 5 is provided with a high-temperature side inlet, a high-temperature side outlet, a side water inlet, a low-temperature inlet, and a low-temperature outlet. The plate heat exchanger 5 is connected to the second outlet on the high-temperature circulation pump 4 through the high-temperature side inlet, and the plate heat exchanger 5 is connected to the side water inlet on the oil heat recovery device 2 through the high-temperature side outlet.

[0023] The oil separator 10 is connected to the exhaust pipe on the screw compressor 8, and a third hot oil outlet pipe is provided on the oil separator 10. The oil separator 10 is connected to the oil heat recovery device 2 through the third hot oil outlet pipe and the second hot oil inlet pipe.

[0024] The low-temperature circulation pump 11 is provided with a third inlet and a third outlet, and the low-temperature circulation pump 11 is connected to the low-temperature inlet of the plate heat exchanger 5 through the third outlet. The water tank 12 is provided with a fourth inlet and a fourth outlet, and the water tank 12 is connected to the low-temperature outlet of the plate heat exchanger 5 through the fourth inlet, and the water tank 12 is connected to the third inlet of the low-temperature circulation pump 11 through the fourth outlet.

[0025] The liquid level sensor 16 is installed on the water tank 12. An electric regulating valve 15 that cooperates with the liquid level sensor 16 is installed on the fourth inlet of the water tank 12. Tap water enters the water tank 12 through the electric regulating valve 15. It is worth noting that the liquid level value detected by the liquid level sensor 16 controls the opening value of the electric regulating valve 15 through the PID adjustment method, so as to control and adjust the amount of tap water entering the water tank 12. The control system compares the liquid level value detected by the liquid level sensor 16 with the set value, and controls the opening of the electric regulating valve 15 through the PID adjustment module to control the liquid level to be constant.

[0026] An oil temperature sensor 6 is installed on the second hot oil outlet of the oil heat recovery device 2, and an electric three-way valve 7 is installed on the side water inlet pipe of the oil heat recovery device 2. It is worth noting that the purpose of waste heat recovery is to maximize the utilization of waste heat of the lubricating oil without affecting the normal operation of the original lubrication system. In order to prevent the oil temperature after heat exchange from being too low, resulting in a decrease in the lubrication effect, the opening of the electric three-way valve 7 is controlled by detecting the oil temperature at the outlet of the oil heat recovery device 2 to ensure that the lubricating oil temperature is always maintained at a normal and safe value.

[0027] The high-temperature circulation pump 4 is located between the oil heat recovery device 2 and the plate heat exchanger 5 , and the high-temperature circulation pump 4 connects the oil heat recovery device 2 and the plate heat exchanger 5 through a first pipeline.

[0028] The low-temperature circulation pump 11 is located between the plate heat exchanger 5 and the water tank 12 , and the low-temperature circulation pump 11 connects the plate heat exchanger 5 and the water tank 12 through a second pipeline.

[0029] The third hot oil outlet pipe of the oil separator 10 is equipped with a direct discharge stop valve 13 and a heat recovery stop valve 14, and the electric control valve 15 is equipped with a PID control module. Figure 2 When the waste heat recovery system is in use, the direct discharge stop valve 13 is closed and the heat recovery stop valve 14 is opened. When the waste heat recovery system is idle, the direct discharge stop valve 13 is opened and the heat recovery stop valve 14 is closed.

[0030] The system is energy-saving and environmentally friendly, economical and efficient, safe and reliable, and easy to promote and apply.

[0031] It should be noted that the specific models and specifications of the oil cooler 1, oil heat recovery device 2, oil pump 3, high-temperature circulation pump 4, plate heat exchanger 5, oil temperature sensor 6, electric three-way valve 7, screw compressor 8, oil filter 9, oil separator 10, low-temperature circulation pump 11, water tank 12, direct discharge stop valve 13, heat recovery stop valve 14, electric regulating valve 15 and liquid level sensor 16 need to be selected and determined according to the actual specifications of the device, and the specific selection calculation method adopts the existing technology in this field, so it is not repeated.

[0032] The present invention can be explained by the following operation mode: Under the premise of ensuring that the oil system can function normally, the waste heat of lubricating oil can be maximized and the recovered waste heat can be used to heat hot water for process production, thereby reducing the consumption of energy such as steam, gas and electricity and reducing operating costs.

[0033] The water in the water tank 12 is indirectly exchanged with the ammonia heat recovery device and the oil heat recovery device 2 through a secondary heat exchanger, which can effectively avoid the pollution of the water stored in the water tank 12 caused by ammonia leakage. At the same time, the circulating water pipeline between the secondary heat exchanger and the heat recovery device is a closed loop, and the pipeline is filled with pure water, which can completely prevent the scaling of the heat exchanger and ensure that the heat exchanger achieves the best heat exchange effect, which is economical, efficient, safe and reliable.

[0034] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A refrigeration unit lubricating oil waste heat recovery system, comprising an oil cooler (1), the oil cooler (1) being provided with a first hot oil inlet pipe and a first hot oil outlet pipe, characterized in that: Also includes: An oil heat recovery device (2), wherein the oil heat recovery device (2) is provided with a second hot oil inlet pipe, a second hot oil outlet pipe, a side water inlet pipe, and a side water outlet pipe, and the oil heat recovery device (2) is connected to the first hot oil inlet pipe on the oil cooler (1) via the second hot oil outlet pipe; An oil pump (3), wherein the oil pump (3) is provided with a first inlet and a first outlet; A high-temperature circulation pump (4), wherein the high-temperature circulation pump (4) is provided with a second inlet and a second outlet, and the high-temperature circulation pump (4) is connected to a side water outlet pipe on the oil heat recovery device (2) via the second inlet; A plate heat exchanger (5), wherein the plate heat exchanger (5) is provided with a high temperature side inlet, a high temperature side outlet, a side water inlet, a low temperature inlet, and a low temperature outlet, wherein the plate heat exchanger (5) is connected to the second outlet of the high temperature circulation pump (4) via the high temperature side inlet, and the plate heat exchanger (5) is connected to the side water inlet of the oil heat recovery device (2) via the high temperature side outlet; A screw compressor (8), wherein the screw compressor (8) is provided with an exhaust pipe and an oil return pipe, and the screw compressor (8) is connected to a first outlet of an oil pump (3); An oil filter (9), the oil filter (9) being used to connect a first hot oil outlet pipe of the oil cooler (1) and a first outlet of the oil pump (3); An oil separator (10), the oil separator (10) being connected to an exhaust pipe on the screw compressor (8), the oil separator (10) being provided with a third hot oil outlet pipe, and the oil separator (10) being connected to the oil heat recovery device (2) via the third hot oil outlet pipe and the second hot oil inlet pipe; A low-temperature circulation pump (11), wherein the low-temperature circulation pump (11) is provided with a third inlet and a third outlet, and the low-temperature circulation pump (11) is connected to the low-temperature inlet of the plate heat exchanger (5) via the third outlet; A water tank (12), wherein the water tank (12) is provided with a fourth inlet and a fourth outlet, the water tank (12) is connected to the low-temperature outlet on the plate heat exchanger (5) via the fourth inlet, and the water tank (12) is connected to the third inlet on the low-temperature circulation pump (11) via the fourth outlet; A liquid level sensor (16), wherein the liquid level sensor (16) is installed on the water tank (12).

2. A refrigeration unit lubricating oil waste heat recovery system according to claim 1, characterized in that: An oil temperature sensor (6) is installed on the second hot oil outlet of the oil heat recovery device (2), and an electric three-way valve (7) is installed on the side water inlet pipe of the oil heat recovery device (2).

3. The refrigeration unit lubricating oil waste heat recovery system according to claim 1, characterized in that: A direct discharge stop valve (13) and a heat recovery stop valve (14) are installed on the third hot oil outlet pipe of the oil separator (10).

4. The refrigeration unit lubricating oil waste heat recovery system according to claim 1, characterized in that: The high-temperature circulation pump (4) is located between the oil heat recovery device (2) and the plate heat exchanger (5), and the high-temperature circulation pump (4) is connected to the oil heat recovery device (2) and the plate heat exchanger (5) via a first pipeline.

5. The refrigeration unit lubricating oil waste heat recovery system according to claim 1, characterized in that: The low-temperature circulation pump (11) is located between the plate heat exchanger (5) and the water tank (12), and the low-temperature circulation pump (11) is connected to the plate heat exchanger (5) and the water tank (12) via a second pipeline.

6. The refrigeration unit lubricating oil waste heat recovery system according to claim 1, characterized in that: An electric regulating valve (15) coordinated with a liquid level sensor (16) is installed on the fourth inlet of the water tank (12).

7. A refrigeration unit lubricating oil waste heat recovery system according to claim 6, characterized in that: The electric regulating valve (15) is equipped with a PID regulating module.

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