Reciprocating Compressors

OPERATING PRINCIPLE

Reciprocating compressors use pistons driven by a crankshaft, which are designed for gas compression. These pistons fall into the category of positive displacement compressors. Positive displacement compressors operate with gases or air in a compressed chamber, the volume of which is mechanically reduced, thereby increasing the pressure accordingly.
The compression cylinders, also called stages, isolate the gas by pressing it. The design of the devices can be of two types (in double-acting devices, compression takes place on both sides of the piston).
Unlike in internal combustion engines, no combustion takes place: gas from the compressor cylinder is exposed to higher pressures than during the suction.
Reciprocating compressors are commonly used in cases where high pressure is required, respectively, at low flows.

ADVANTAGES

• A wide range of applications: the compressors of this type can compress various gases such as refrigerant, hydrogen, natural gas, etc. They can, therefore, be used in multiple industries, such as construction, refrigeration, mining, metallurgy, etc.
• A wide range of volume capacities: welded hermetic compressors are designed as very low power units and can, therefore, be used in household refrigerators. Open-type semi-pressurised compressors are typically designed up to 100 tonnes (350 kW) and are therefore are suitable for household and commercial air-conditioning installations.

LIMITATIONS

• Low energy consumption efficiency: this type of compressors is characterised by losses, i.e. the result of the gas leak between the piston and the cylinder and the operation of the quick suction and discharge valves.
• Compared to other types, these compressors are more substantial in volume and weight.
• Due to a complex structure, these compressors are more challenging to maintain.
• Due to continuous gas displacement, these compressors are characterised by vibration.

APPLICABILITY

Reciprocating compressors are used for compression of natural gas (in pipelines), supply of high-pressure gas in various industrial or chemical conditioning and refrigeration systems.