6 Design and Operation of Compressors

Compressors and their drivers are the workhorses of the gas pipeline industry. They come in different combinations with the most common ones being reciprocating compressors driven by electric motors or engines and centrifugal compressors driven usually by gas turbines and increasingly by electric motors. Other types of compressors are not normally used on pipelines because they do not provide the most optimum match of pressure ratio and flow other than screw compressors in upstream gathering systems. In general, pipeline compressors occupy the middle ground in terms of pressure ratio and flow. Reciprocating compressors are the better choice for medium-pressure ratio applications, and moderate flows and centrifugal compressors are preferred for lower pressure ratios and higher flows.