Compressor

by: muhammad suhandi

Compressor is used to produce compressed air. This compressed air is used in many applications such as drilling, food processing, milling, tooling etc. Pressured air produced range from 25 psig (172 kPa) to 60,000 psig (413,790 kPa). Normally usage is in range 90 to 110 psig.

There are two designs for compressor, positive displacement and dynamic compressor. The positive displacement takes a constant volume of gas and compressed it. The dynamic compressor operates by transferring momentum from high speed rotor into the gas.

The efficiency of compressor is largely depends in many factors for instance the inlet gas temperature, leak in compression chamber and etc. The pressure ratio between inlet and outlet of compressor is limited by temperature rise and mechanical stress. To achieve higher pressure, compressor arranged in cascaded resulting multistage compressor.

As mention previously, there are two types of compressor. These two types are divided more,

1. Positive displacement
a. Reciprocating
· Single acting
· Double acting
· Diaphragm
b. Rotary
· Lobe
· Screw
· Scroll
· Vane
2. Dynamic
a. Centrifugal
b. Axial

Dynamic compressor relatively needed in applications that require high flow rates. The centrifugal type has impeller rotate inside housing and move the gas radial. The axial type has arrays of blade rotate in housing cause the gas to flow axially for instance in exhaust fan. The axial compressor used in gas turbine and in many applications in plants.

Positive displacement pump needed in applications require high pressure. It relatively has larger volumetric efficiency compare to dynamic compressor. The reciprocating pump consists of pistons moved by crankshaft that further turned by electric motor or internal combustion engine. This type of compressor ranging from small horse power 5 to 30 HP such as in automotive and as large as 1000 HP such as used in oil and gas industry. This type is said to be the most efficient compressor. Rotary screw compressor consists of two positive displacement screws in mesh that force the gas to flow into continuously space becoming smaller.

Because the increases of fuel price the manufactures around the world continuously strive to design the more efficient compressor. They compete not only in the more efficient but also more inexpensive price offered to customers.

Modern compressor is controlled by sophisticated electronic control. With multiple option of operation we can select the optimum state the way the compressor works.