The oil separator functions to separate the lubricating oil in the high-pressure steam discharged from the refrigeration compressor to ensure safe and efficient operation of the device. According to the principle of reducing the gas flow rate and changing the direction of the gas flow, the oil particles in the high pressure steam are separated by gravity. Commonly used oil separators are washing, centrifugal, packing and filtering.
Structure: The oil separator is installed between the compressor outlet and the condenser inlet. Through separation, the heat transfer effect in the condenser and the evaporator is improved. For systems with poor compatibility between lubricating oil and working fluid, oil separation The device is more important.
working principle:
After the high pressure gas from the compressor enters the oil separator, it enters the guide vane of the oil separator and spirals along the guide vane. The centrifugal oil and gravity separate the lubricating oil from the working gas, along the inner wall of the cylinder. Flow down. The working gas is led out of the oil separator by a central tube through a porous baffle. The separated lubricating oil is concentrated in the lower part of the oil separator and can be discharged periodically, or the floating ball valve is used to automatically return the lubricating oil to the crankcase of the compressor.
effect:
In a vapor compression refrigeration system, the compressed ammonia vapor is in a superheated state at a high pressure and a high temperature, because the flow rate is high and the temperature is high when it is discharged. Part of the lubricating oil on the cylinder wall, due to the high temperature, it is inevitable that the oil vapor and oil droplet particles will be discharged together with the refrigerant vapor, and the higher the exhaust steam temperature and the faster the flow rate, the more lubricating oil is discharged.
Filter oil separator:
When the high-pressure refrigerant gas discharged from the compressor enters the separator, the gas flow rate suddenly decreases and changes direction due to the large flow cross section, and the filtration effect of several layers of wire mesh at the time of intake is about to be mixed into the gas refrigerant. The lubricating oil is separated and dripped down to gather at the bottom of the container. When the amount of accumulated lubricating oil reaches a certain height, it is returned to the compressor crankcase through the automatic oil return valve. In normal operation, due to the intermittent operation of the float valve, the return pipe is hot when it is cold, the pipe is hot when returning to the oil, and the pipe is cold when the oil is not returned. If the return line is always cold or hot, this means that the float valve has failed and must be serviced. The manual return valve can be used for oil return during maintenance. The oil separator has a simple structure, is convenient to manufacture, and is generally used, but the oil separation effect is not as good as the filler type.
Centrifugal oil separator:
The centrifugal oil separator has good oil separation effect and is suitable for large-scale refrigeration systems. The exhaust gas of the compressor enters the cylinder along the tangential direction through the oil separator inlet pipe, and then rotates along the spiral guide blade at a high speed and flows from top to bottom. By the action of centrifugal force, the oil droplets with higher density in the exhaust gas are thrown on the wall of the cylinder and separated, flowing down the wall and deposited on the bottom of the cylinder. The vapor is drawn through the perforated plate in the outlet pipe at the center of the cylinder. The float side valve is installed on the cylinder side. When the oil level rises to the upper limit position, the lubricating oil opens the valve core through the float ball valve and automatically drains the oil to the compressor crankcase or the oil collector. Some of them are provided with a cooling water jacket outside the oil separator, so that the mixed vapor body is cooled by the cooling water therein and further separated by reducing the flow velocity and changing the flow direction.
