COMPRESSOR a machine that increases the pressure of a gas or vapor (typically air), or mixture of gases and vapors. The pressure of the fluid is increased by reducing the fluid specific volume during passage of the fluid through the compressor. When compared with centrifugal or axial-flow fans on the basis of discharge pressure, compressors are generally classed as high-pressure and fans as low-pressure machines.
TYPES OF COMPRESSOR
Compressors fall into two groups:
The first group operates on the displacement principle where is compressed by containing it in a chamber and then reducing the volume of this chamber. This type is called piston compressor. (Reciprocating piston compressor, rotary piston compressor.)
The second group operates on the air-flow principle: by drawing in air on side and compressing it by mass acceleration (Turbine.)
RECIPROCATING PISTON COMPRESSOR
The reciprocating piston compressor is, at the present time, the most widely used compressor. It can be used not only for compressing to low and medium pressures, but also to high pressure. The pressure range extends from approx. 100 kPa (1 bar/14.5 psi) up to several thousand kPa (bar/psi).
This type of compressor belongs to the piston compressor group. The piston is separated from the suction chamber by a diaphragm, i.e. the air does not come into contact with the reciprocating parts. Thus, air is always kept free of oil. For this reason, its use is preferred in the foodstuffs industry, pharmaceutical and the chemical industries.
ROTARY PISTON COMPRESSORS
The rotary piston compressor is a compressor with rotating pistons. At the same time, chambers are compacted and the air in these chambers is compressed.
SLIDING VANE ROTARY COMPRESSOR
Sliding vanes are contained in slots in the rotor and form chambers with the cylindrical wall. When rotating, the centrifugal energy forces the vanes against the wall, and owing to the shape of the housing the chambers are increased or reduced in size.
TWO-AXLE SCREW COMPRESSOR
Two intermeshing rotors, one having a convex profile and the other a concave profile. Displace the axial entering air to the other side
In these compressors, the air is conveyed from one side to the other without any change in volume. The piston edges produce sealing on the pressure side.
These work on the air-flow principle and are especially suitable for large delivery volumes. Flow compressors are made as axial and radial types.
The air state is converted in one or more turbine wheels to flow velocity. This kinetic energy is converted to pressure energy.
AXIAL FLOW COMPRESSOR
The air is accelerated by the blades in an axial direction of flow
Acceleration from chamber to chamber radially outwards, reversal of the flowing air and return to the shaft. From there, again acceleration outwards