Instrumentaton and Control System Blog

The purpose of an anti-surge control is to keep the compressor from going into surge on reduced flow. Surge is an instability exhibited by a centrifugal as flow is reduced below the surge point. An anti-surge control is recommended for all centrifugal compressor applications. Pipelines transporting gases and vapours are invariably dependent on centrifugal or turbo-compressors for the propulsion of these fluids. Under normal operation, with the compressor running at any constant speed there is a specific relationship between the pressure head across the compressor and the flow through it. But this stable relationship can be disturbed by sudden changes in flow, pressure and density, usually caused by sudden variations in demand downstream of...