The screw compressor is a positive displacement twin-screw oil-injected compressor, which is generally a box-type skid-mounted structure. Today, I want to share with you the relevant knowledge of the structure and working principle of the screw compressor. Let’s learn about it together!
Features of screw compressor
As a kind of rotary refrigeration compressor, screw refrigeration compressor has the characteristics of both piston type and power type (speed type).
1) Compared with the reciprocating piston refrigeration compressor, the screw compressor has a series of advantages such as high speed, light weight, small volume, small footprint and low exhaust pulsation.
2) The screw compressor has no reciprocating mass inertia force, good dynamic balance performance, stable operation, small vibration of the base, and a small foundation.
3) The screw compressor has a simple structure, a small number of parts, and no wearing parts such as air valves, piston rings, etc. Its main friction parts such as rotors, bearings, etc., have high strength and wear resistance, and the lubrication conditions Therefore, the machining volume is small, the material consumption is low, the operation cycle is long, the use is relatively reliable, and the maintenance is simple, which is conducive to the realization of operation automation.
4) Compared with the speed compressor, the screw compressor has the characteristics of forced gas delivery, that is, the displacement is almost not affected by the exhaust pressure, and the surge phenomenon does not occur when the displacement is small. Within the range of operating conditions, high efficiency can still be maintained.
5) The slide valve adjustment is adopted, which can realize the stepless adjustment of energy.
6) The screw compressor is not sensitive to the liquid inlet and can be cooled by oil injection. Therefore, under the same pressure ratio, the discharge temperature is much lower than that of the piston type, so the single-stage pressure ratio is high.
7) There is no clearance volume, so the volumetric efficiency is high.
The core structure of the screw compressor
Refrigeration oil has the following functions
A) Dynamic sealing between adjacent rotors
B) Bearing lubrication
C) Slide valve control for cooling capacity adjustment
D) cooling compressor
(1) Oil separator of screw air copmreseeor
The separation of oil from the refrigerant is ensured by the following conditions: 1. Different flow rates of oil and gas; 2. Flow to the oil tank after hitting the wall; 3. Blocked after passing through the "atomizer assembly".
(2) Oil filter of screw air copmreseeor
Clean status is indicated by pressure drop, normal pressure drop < 1 bar, if DP (differential pressure) > 3.5 then the filter is dirty and must be replaced.
(4) Oil level of screw air copmreseeor
Oil level: It can be observed through the sight glass. Usually, the oil level should be kept between 1/2 - 3/4 of the sight glass. In any case, the oil level can be observed through the sight glass, for a long time or too much. The bubbles all indicate that the oil is diluted by the refrigerant.
