Selection of Oil Separators and Oil Return Control | Solution to Oil Leakage Faults in Screw and Piston Units
The core function of the oil separator is to separate and intercept the refrigeration oil carried in the compressor exhaust, and send it back to the crankcase through the return oil capillary tube, reducing the accumulation of oil entering the evaporator.
The load pressure of the piston compressor oil is relatively low, and a baffle type oil separator is selected; The exhaust oil content of screw compressors is high, and high-efficiency centrifugal+filter composite oil separators are preferred.
The Xitelidou large cooling screw unit is equipped with an external oil separator as standard, with an oil separation efficiency of ≥ 99%, ensuring long-term operation of the system and preventing oil accumulation and heat transfer attenuation in the evaporator.
The oil return capillary tube has a one-way valve structure. After the one-way valve gets stuck or clogged, the separated oil accumulates inside the oil separator, and the crankcase continues to sound an oil shortage alarm.
Many engineering companies choose small oil fractions to reduce costs, with small volumes, excessive flow rates, decreased separation efficiency, and system oil leakage. They need to add extra refrigeration oil every three months.
The return oil pressure difference is a prerequisite for the normal operation of oil distribution. If the pressure difference between the high pressure on the exhaust side and the low pressure on the crankcase is less than 0.3MPa, the return oil will be slow or even stop.
Low temperature long pipeline quick freezing tunnel, in addition to the main engine oil, an oil collector is added at the outlet of the evaporator to assist in collecting retained frozen oil, and oil is manually returned regularly.
The long-distance pipeline and multi parallel evaporator scheme for foreign trade projects should be separately labeled with oil specifications and return pipe diameter in the technical scheme to avoid on-site selection of smaller sizes.
Typical characteristics of clogged internal filter element in oil separation: increased exhaust resistance, increased unit high pressure, decreased cooling capacity, and pressure difference exceeding 0.12MPa. It is recommended to disassemble, clean or replace the filter element.
The piston engine itself comes with internal oil separation, and short tube small and medium-sized fresh-keeping warehouses can eliminate the need for external oil separation; It is recommended to install an external oil separator for low temperature, long pipeline, and continuous operation conditions.
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FAQ
What is the difference in oil types between piston engines and screw engines? Pistons often use baffle type, while screws often use composite high-efficiency oil separation.
What is the pressure difference required for normal oil return? Ensure a pressure difference of at least 0.3MPa.
3. What is the recommended maintenance and replacement for the differential pressure of the oil filter element? If the pressure difference exceeds 0.12MPa, it needs to be treated.
What happens when the oil check valve is blocked? The oil remains in the oil fraction, and the crankcase is short of oil.
5. Should small and medium-sized preservation piston storage tanks with short pipelines be equipped with external oil separators? No need to install, rely on the built-in oil component.
What is the high standard for oil separation efficiency? The separation efficiency of high-efficiency models can reach 99%.
Why add an additional oil collector to the frozen long pipeline? Collect frozen oil trapped in the evaporator and assist in oil return.
