Compressor

A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. As gases are compressible, the compressor also reduces the volume of a gas. Liquids are relatively incompressible; while some can be compressed, the main action is to pressurize and transport fluid.

Type of compressors
• Positive displacement
o Rotary (Screw, Vane and Scroll)
o Reciprocating (Single, and double acting)
• Dynamic
o Centrifugal
o Axial

 

Type based on usage
• Air Compressors
• Gas Compressors
An air compressor is a specific type of gas compressor. Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe.

Work
This radial movement of air results in a pressure rise and the generation of kinetic energy. Before the air is led into the center of the impeller, the kinetic energy is also converted into pressure by passing through a diffuser and volute. Each stage takes up a part of the overall pressure rise of the compressor unit

 

Centrifugal Compressor’s surge
Surge is defined as the operating point at which centrifugal compressor peak head capability and minimum flow limits are reached. Actually, the working principle of a centrifugal compressor is increasing the kinetic energy of the fluid with a rotating impeller

Reciprocating Vs. rotary Compressor
Double-acting reciprocating compressors typically require more periodic maintenance than rotary screws. Valves, piston rings, and other consumables on a reciprocating compressor need expensive routine maintenance. Rotary screw compressor maintenance is limited mostly to oil, oil filter, and air/oil separator changes.

Types of air compressors
Most air compressors either are reciprocating piston type, rotary vane or rotary screw. Centrifugal compressors are common in very large applications. There are two main types of air-compressor pumps: oil-lubed and oil-less.

Screw compressor vs. Reciprocating compressor
 

Rotary screw compressors use two meshing helical screws, known as rotors or air-end, to compress the air. Reciprocating (Piston Type) compressors use pistons driven by a crankshaft to compress the air.

Multi stage Compressor
As noted in the compressor descriptions, most compressor designs are available in single or multiple stage designs. When air is compressed, its temperature increases. However, in a two-stage compressor, air is partially compressed using isentropic compression, and then cooled in a heat exchanger, called an intercooler.

Single stage Compressor
Single stage compressors are also known as piston compressors. The process that takes place within a single stage compressor goes as follows: Air is sucked into a cylinder. The trapped air is compressed in a single stroke with a piston at roughly 120 psi.
Advantage of scroll compressor
Advantages of scroll compressors. The absence of pistons for gas compression enables scroll compressors to reach 100% volumetric efficiency, leading to reduced energy costs. Re-expansion losses, a typical feature of each piston stroke encountered in reciprocating models, are eliminated

 

Screw compressor
A rotary-screw compressor is a type of gas compressor that uses a rotary-type positive-displacement mechanism. They are commonly used to replace piston compressors where large volumes of high-pressure air are needed, either for large industrial applications or to operate high-power air tools such as jackhammers.

Scroll compressor
Unlike reciprocating technology with many moving parts, the Copeland scroll compressor has one scroll or spiral orbiting in path defined by a matching fixed scroll. The fixed scroll is attached to the compressor body. The orbiting scroll is couple to the crankshaft in orbit rather then rotated.

 

Rotary vane compressor
The rotary vane (sliding vane) compressor is a rotary type compressor, meaning a rotating device is used to compress gas. Vanes on the rotor trap gas between the rotor and cylinder walls. This gas is compressed and released into the discharge line.