An ammonia refrigeration system with an oil separator replacing an oil collector and a method of using the same

Abstract

The present application relates to an ammonia refrigeration system with an oil separator instead of an oil collector and a use method thereof. The problem to be solved is that an ammonia system needs to additionally configure an oil return device for oil return, resulting in complex system operation, non-energy saving and high cost. The technical solution for solving the technical problem is that the high-pressure side oil return cycle is that the H port of the liquid receiver is connected to the oil return valve I through a pipeline and then returns to the D port of the oil separator; the low-pressure side oil return cycle is that the K port of the evaporator is connected to the oil return valve II through a pipeline and then returns to the C port of the oil separator. The ammonia refrigeration system is suitable.

Description

Technical Field

[0001] This invention pertains to refrigeration technology, specifically an ammonia refrigeration system and its usage method that uses an oil separator instead of an oil collector. Background Technology

[0002] In a refrigeration system, some lubricating oil from the compressor enters the oil separator along with the high-temperature, high-pressure gas after compression. The oil separator separates the lubricating oil, but it is impossible for the oil separator to separate 100% of the lubricating oil from the exhaust. A small amount of lubricating oil will enter the system with the refrigerant. If the oil return is not handled properly during operation, the compressor is at risk of "oil runaway". Therefore, it is necessary to configure a reasonable oil return device to return the lubricating oil to the compressor. In existing ammonia refrigeration systems, the commonly used oil return method involves an ammonia oil collector. The operation is as follows: after the compressor stops, when oil return is needed, the return gas valve is opened. If oil return is needed from the high-pressure side liquid receiver, return oil valve one is opened (this valve is a regulating valve). The pressure difference allows the lubricating oil in the liquid receiver to flow into the oil collector. If oil return is needed from the low-pressure side evaporator, return oil valve two is opened. Gravity allows the lubricating oil in the evaporator to flow back into the oil collector. The frost formation on the oil collector cylinder is observed to determine the internal liquid level, and either return oil valve one or return oil valve two is closed. Through heat exchange with the environment via the oil collector, the ammonia liquid evaporates into gas and returns to the low-pressure side gas phase region. The lubricating oil accumulates at the bottom of the oil collector. This lubricating oil can be drained through the drain valve at the bottom of the oil collector. Alternatively, during compressor operation, the return gas valve can be closed, and the pressurization valve and return oil valve three can be opened, using the pressure difference to draw the lubricating oil back to the compressor. This oil return method is complex and does not save energy by utilizing discharge pressure. Summary of the Invention

[0003] The purpose of this invention is to propose an ammonia refrigeration system and its usage method that uses an oil separator instead of an oil collector, to solve the problems existing in the background technology: ammonia systems require an additional oil return device for oil return, resulting in complex system operation, energy inefficiency, and high cost. The technical solution adopted to solve this problem is: an ammonia refrigeration system that uses an oil separator instead of an oil collector, wherein the refrigeration cycle is as follows: the compressor discharge port is connected sequentially through pipelines to oil separator ports A and B, condenser, liquid receiver ports F and G, expansion valve, evaporator ports I and J, and port L in the pipeline back to the compressor suction port; oil separator port E is connected sequentially through pipelines to a pressure equalization valve and port L in the pipeline; the key feature is that: the high-pressure side oil return cycle is: the liquid receiver port H is connected through a pipeline to an oil return valve and then back to the oil separator port D; the low-pressure side oil return cycle is: the evaporator port K... After being connected to the return oil valve 2 via a pipeline, the oil returns to port C of the oil separator. Ports C and D on the oil separator can be either two ports or one port. Port K can be located on the evaporator, the gas-liquid separator, or the low-pressure circulation tank. The gas-liquid separator and the low-pressure circulation tank are auxiliary equipment connected to this system. Port E can be located on the oil separator or on the pipeline between the compressor and the oil separator. Port L can be located in the low-pressure zone of the compressor, between the evaporator and the compressor, or between the expansion valve and the evaporator. A method for using an ammonia refrigeration system with an oil separator replacing an oil collector, as described above, is characterized by the following oil return operation: After the compressor stops, first open the equalizing valve; after equalization is completed, close the equalizing valve; when the high-pressure side liquid receiver needs oil return, open oil return valve one; since the pressure inside the liquid receiver is higher than that of the oil separator, the lubricating oil in the liquid receiver can be returned to the oil separator through the pressure difference; after the oil is discharged, close oil return valve one; when the low-pressure side evaporator needs oil return, when the evaporator installation height is higher than that of the oil separator, open oil return valve two; the oil can be returned by gravity. The lubricating oil in the evaporator is drained back into the oil separator. When the evaporator is installed at a height lower than the oil separator, close the compressor's discharge valve or suction valve. After the evaporator temperature rises, the pressure inside the evaporator increases. Open the second oil return valve and drain the lubricating oil in the evaporator back into the oil separator through the pressure difference. Alternatively, open the liquid supply expansion valve to allow high-pressure liquid to enter the evaporator through the expansion valve. The flashing gas causes the pressure inside the evaporator to increase, and the lubricating oil in the evaporator is drained back into the oil separator through the pressure difference. After draining the oil, close the second oil return valve and open the compressor's discharge valve or suction valve.

[0004] The beneficial effects of this invention compared to the prior art are as follows: Using the above technical solution, on the one hand, the oil return operation is as follows: after the compressor stops, the pressure equalization valve is opened first; after pressure equalization is completed, the pressure equalization valve is closed. When the high-pressure side reservoir needs oil return, oil return valve one is opened. Because the pressure inside the reservoir is higher than that in the oil separator, the lubricating oil in the reservoir can be returned to the oil separator through the pressure difference. After the oil is discharged, oil return valve one is closed. When the low-pressure side evaporator requires oil return, if the evaporator is installed higher than the oil separator, open oil return valve two, and gravity will allow the lubricating oil in the evaporator to return to the oil separator. If the evaporator is installed lower than the oil separator, close the compressor's discharge or suction valve. After the evaporator temperature rises, the pressure inside the evaporator increases, and oil return valve two is opened, allowing the lubricating oil in the evaporator to return to the oil separator through the pressure difference. Alternatively, the liquid supply expansion valve can be opened, allowing high-pressure liquid to enter the evaporator through the expansion valve. The flashing gas increases the pressure inside the evaporator, and the lubricating oil in the evaporator is returned to the oil separator through the pressure difference. After the oil is drained, close oil return valve two and open the compressor's discharge or suction valve. This system achieves oil return through simple valve operation, simplifying system operation and ensuring system safety and reliability. Furthermore, this system requires no other oil return device or additional pressurization device, making it energy-efficient and highly effective. On the other hand, the small amount of refrigerant that is put into the oil separator along with the lubricating oil is heated and evaporated into gas by the heat of the high-temperature lubricating oil, thus avoiding the problem of "oil run-out" when the oil separator is turned on next time. Attached Figure Description

[0005] Figure 1 This is a schematic diagram of the present invention. Detailed Implementation

[0006] Example: Reference Figure 1An ammonia refrigeration system in which an oil separator replaces an oil collector, wherein the refrigeration cycle is as follows: the discharge port of compressor 1 is connected in sequence through pipelines to ports A and B of oil separator 3, condenser 5, ports F and G of liquid receiver 4, expansion valve 7 and ports I and J of evaporator 9, and port L in the pipeline returns to the suction port of compressor 1; port E of oil separator 3 is connected in sequence through pipelines to pressure equalization valve 2 and port L in the pipeline, characterized in that: the high-pressure side oil return cycle is: port H of liquid receiver 4 is connected through pipelines to return oil valve 6 and returns to port D of oil separator 3; the low-pressure side oil return cycle is: port K of evaporator 9 is connected through pipelines to return oil valve 8 and returns to port C of oil separator 3; ports C and D on oil separator 3 are two ports; port K is located on evaporator 9; port E is located on oil separator 3; port L is located between evaporator 9 and compressor 1. A method for using an ammonia refrigeration system with an oil separator replacing an oil collector, as described above, is characterized by the following oil return operation: After compressor 1 stops, pressure equalization valve 2 is opened first, and after pressure equalization is completed, pressure equalization valve 2 is closed; when oil return is needed in the high-pressure side liquid receiver 4, oil return valve 6 is opened. Since the pressure inside the liquid receiver 4 is higher than that in the oil separator 3, the lubricating oil in the liquid receiver 4 can be returned to the oil separator 3 through pressure difference. After the oil is discharged, oil return valve 6 is closed; when oil return is needed in the low-pressure side evaporator 9, when the installation height of the evaporator 9 is higher than that of the oil separator 3, oil return valve 8 is opened, and the evaporator can be discharged by gravity. The lubricating oil in evaporator 9 is returned to oil separator 3. When the installation height of evaporator 9 is lower than that of oil separator 3, the exhaust valve or suction valve of compressor 1 is closed. After the temperature of evaporator 9 rises, the pressure inside evaporator 9 increases. Then, the oil return valve 8 is opened, and the lubricating oil in evaporator 9 is returned to oil separator 3 through the pressure difference. Alternatively, the liquid supply expansion valve 7 can be opened to allow high-pressure liquid to enter evaporator 9 through the expansion valve 7. The flashing gas causes the pressure inside evaporator 9 to increase. The lubricating oil in evaporator 9 is then returned to oil separator 3 through the pressure difference. After the oil is drained, the oil return valve 8 is closed, and the exhaust valve or suction valve of compressor 1 is opened.

Claims

1. An ammonia refrigeration system in which an oil separator replaces an oil collector, wherein the refrigeration cycle is as follows: the discharge port of the compressor (1) is connected in sequence through a pipeline to the A and B ports of the oil separator (3), the condenser (5), the F and G ports of the receiver (4), the expansion valve (7), and the I and J ports of the evaporator (9), and the L port in the pipeline returns to the suction port of the compressor (1); the E port of the oil separator (3) is connected in sequence through a pipeline to the equalizing valve (2) and the L port in the pipeline, characterized in that: The high-pressure side return oil circulation is: the H port of the reservoir (4) is connected to the return oil valve one (6) through the pipeline and then returns to the D port of the oil separator (3); the low-pressure side return oil circulation is: the K port of the evaporator (9) is connected to the return oil valve two (8) through the pipeline and then returns to the C port of the oil separator (3).

2. The ammonia refrigeration system according to claim 1, wherein the oil separator replaces the oil collector, characterized in that: The C port and D port on the oil separator (3) can be either two ports or one port.

3. An ammonia refrigeration system that replaces an oil collector with an oil separator according to claim 1 or 2, characterized in that: The K port can be located on the evaporator (9), the gas-liquid separator, or the low-pressure circulation tank.

4. An ammonia refrigeration system that replaces an oil collector with an oil separator according to claim 1 or 2, characterized in that: Port E can be located on the oil separator (3) or on the pipeline between the compressor (1) and the oil separator (3).

5. An ammonia refrigeration system according to claim 3, wherein the oil separator replaces the oil collector, characterized in that: Port E can be located on the oil separator (3) or on the pipeline between the compressor (1) and the oil separator (3).

6. An ammonia refrigeration system that replaces an oil collector with an oil separator according to claim 1 or 2, characterized in that: The L port can be located either in the low-pressure zone of the compressor (1), between the evaporator (9) and the compressor (1), or between the expansion valve (7) and the evaporator (9).

7. An ammonia refrigeration system according to claim 3, wherein the oil separator replaces the oil collector, characterized in that: The L port can be located either in the low-pressure zone of the compressor (1), between the evaporator (9) and the compressor (1), or between the expansion valve (7) and the evaporator (9).

8. An ammonia refrigeration system according to claim 4, wherein the oil separator replaces the oil collector, characterized in that: The L port can be located either in the low-pressure zone of the compressor (1), between the evaporator (9) and the compressor (1), or between the expansion valve (7) and the evaporator (9).

9. A method of using an ammonia refrigeration system as described in claim 1, wherein the oil separator replaces the oil collector, characterized in that: The oil return operation is as follows: After the compressor (1) stops, first open the equalizing valve (2), and after the equalization is completed, close the equalizing valve (2); when the high-pressure side liquid receiver (4) needs to return oil, open the first oil return valve (6). Since the pressure inside the liquid receiver (4) is higher than that inside the oil separator (3), the lubricating oil inside the liquid receiver (4) can be returned to the oil separator (3) through the pressure difference. After the oil is returned, close the first oil return valve (6); when the low-pressure side evaporator (9) needs to return oil, when the installation height of the evaporator (9) is higher than that of the oil separator (3), open the second oil return valve (8). The lubricating oil inside the evaporator (9) can be returned to the oil separator (3) by gravity; when When the evaporator (9) is installed at a height lower than the oil separator (3), close the exhaust valve or suction valve of the compressor (1). After the temperature of the evaporator (9) rises, the pressure inside the evaporator (9) increases. Open the return oil valve (8) and return the lubricating oil in the evaporator (9) to the oil separator (3) through the pressure difference. Alternatively, open the liquid supply expansion valve (7) to allow high-pressure liquid to enter the evaporator (9) through the expansion valve (7). The flashing gas causes the pressure inside the evaporator (9) to increase. Return the lubricating oil in the evaporator (9) to the oil separator (3) through the pressure difference. After the oil is drained, close the return oil valve (8) and open the exhaust valve or suction valve of the compressor (1).

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