Electrical Power Savings in Pump and Compressor Networks via Load Management

Abstract

Large industrial plants commonly use multiple parallel units in pump and compressor networks for improved reliability. Sometimes, installed equipment capacity can far exceed actual requirements. This excess capacity can be translated into energy cost savings through “optimum load management”. A key decision parameter in determining the operating policy is the Trigger Point at which to switch from N units to N+1, and vice versa. The Trigger Point is defined as the actual flow rate at which the switching is made to the “ideal” (generally maximum) flow rate at which the switching should be made. At the plant under study, the implicit Trigger Point was generally found to be around 85%, probably because this made it easy to have a smooth transition during the switching operation. A number of pumping and compression networks were analyzed to determine what the potential savings would be if this trigger point were increased to 90 or 95%. The savings potential was found to range from 0 to 23%, with an average of 4.4%. Our study demonstrated that by tightening up operating policies to make sure that the minimum number of machines is being run, significant cost savings are possible with zero capital investment, and negligible sacrifice in operating flexibility or reliability. This paper describes the methodology used, as well as representative results from our study.