Four Types of Compressors Used in Gas Recovery Systems

There are many applications of compressed gas being used in the world around us. In many cases, gas is a byproduct of a process that manufacturers try to capture these gases before they are released into our environment. Hydrogen gas recovery systems are often a part of an overall extraction and refining process, and these systems are designed to capture gas and vapor compounds that can be used or resold to gas purification partners.

These are the four main types of compressors used in processes involving oil and gas production.

Diaphragm

Reciprocating gas compressors are also referred to as a positive displacement compressor. In this system, the movement of a piston (driven by a crankshaft) drives the compression of the gas. One of the three kinds of reciprocating gas compressors is the diaphragm gas compressor (the other two being the single-acting and double-acting compressors).

A specialized iteration of the reciprocating compressor, a diaphragm compressor uses a motor-mounted concentric that provides movement to a flexible disc. The role of the disc is to expand and contract the compression chamber’s volume alternatively — mimicking how a diaphragm pump works.

When the chamber’s volume is reduced, it pushes the gas out of the compressor. In this compressor, the lubricating oil from the compressor or the hydraulic fluid doesn’t come in contact with the process gas. This maintains the purity of the compressed gas, making it the go-to compressor type for industries that require very clean air (e.g., medical players).

Rotary

Gas compression players typically categorize compressors into positive displacement and dynamic. Each of these two further comprises two sub-categories. For positive displacement, you have the rotary and reciprocating compressors.

Rotary compression systems, as their name states, compress gas using a rotary motion. A rotor rotates the shaft, which then drives the compression process through the eccentric motion of an impeller affixed to the shaft. The shaft rotates around its axis.

During the process, a vacuum is created at the center of the impeller blades, creating a suction area through which the gas enters the impeller. As the impeller spins, the gas is compressed to a higher pressure, and when the gas reaches the end of the impeller, it exits and travels back towards the center part. At this point, the gas passes through the gap between the impeller and the housing. Once again, the gas is compressed, and its pressure increases. Finally, the gas leaves the impeller and goes into the outlet pipe.

Rotary compressors have different types including lobe, screw, liquid ring, scroll, and vane.

Centrifugal

The gas is moved from low to high pressure inside a high quality pressure vessel. In dynamic compressors, a velocity head is being imparted to the gas, which is then transformed into a pressure head as the gas enters the discharge line.

Gas and nitrogen compressor manufacturers further classify dynamic compressors into two: centrifugal and axial. In the former, velocity is imparted to gases through high-speed impellers. The spinning impeller moves the gas outward and then the gas expands in a casing volute. In the casing volute, the pressure of the gas rises as the velocity slows down.

Axial

Axial compressor — one kind high pressure compressor is used in some hydrogen compressor systems — delivers large flow volumes at greater pressure ratios, thanks to the unidirectional flow of the air that it facilitates. This compressor is usually used by industries that require a high flow rate with efficiency. They can be found in many gas turbine plants and natural gas pumping stations.