Screw Compressors – A Look at Processes, Types and Applications
Screw compressors are specially made to handle a wide array of dry material transfer ranging from granulates, cement and plastics to sand, flour, lime and silicate. Its body contains two forms of screws further known as the female and male screws. Female pins are those with concave inlets while male screws have convex ones.
Screw compressors operate in opposite directions. It is the female screw that receives the driving power. The male screw, on the other hand, is responsible for transmitting the power driven by the female version. It passes through a set of the so-called synchronization gears.
The two most commonly used compressors today are the rotary screw (helical rotor) and the reciprocating piston. In the comparison of the two, the rotary screw does not use valves, is lighter in weight than the reciprocating piston, is pulsation free making foundation requirements less extreme and maintains its design efficiency over operational time as the rotors never come in contact with each other. The screw pin compressor was originally conceived in the mid-1950’s and eventually developed to operate between the reciprocating piston and centrifugal machine capabilities for commercial, industrial and gas type applications.
Processes
Aside from the major roles of male and female screws in a compressor, there are other essential parts of the process. While the bolts start rotating, the admission process takes place. This is where the air fills the inlet port thereby occupying the space between the two screws.
Next to the admission phase is the compression step. This is when the male thread stops or blocks the female thread. During this stage, the rotation of the screws starts to decrease. As soon as the volume reaches the compressor’s delivery outlet, then the exhaust phase takes place.
The exhaust phase is that instance when the screws no longer have contact with each other. Total reliability is obtained during the procedure thus allowing the screw compressors to be of great use to several applications. Typical examples are hydraulic power systems, electric motor and stationary and mobile applications.
The different types and their specific applications
There is one type known as the rotary screw pin compressor. This is found in the kinds of gas compressors. It uses a mechanism through a single screw or a double counter helical screw. While the mechanism does its work, gas can be drawn through the casing’s port then captured in an individual cavity. Discharge of the gas is then made to another port in the housing. This type of screw pin compressor is applied in general industries like those trailer units powered by diesel as seen on construction sites.
Another particular type is the oil-flooded compressor. This is often functional in sealing and cooling gas charges. As the oil flows in the process, it undergoes separation from the discharge stream before it is cooled and filtered. Later on, the oil is recycled.
Oil-free compressors are also examples of this industrial machinery. Without the presence of any oil, air compression is made probable by the bolts. This type is relatively important in medical researchers as well as in semiconductor industries.