Pumping Applications in the Petroleum and Chemical Industries

There has been a great deal of discussion and literature on saving electrical energy used by centrifugal pumps. Most of the attention, however, has been given to one general type of centrifugal pump application-variable-flow variable-pressure-and the role of the control loops of the system has generally not been dealt with. In actual practice, centrifugal pump applications can be classified into three general types: 1) variable-flow variable-pressure; 2) constant-flow variable-pressure; and 3) variable-flow constant-pressure. The actual type is determined by the control loops of the system. A user who is interested in implementing an energy savings program by using electrical adjustable speed control must select and analyze specific applications, which may fall into any of the above three categories. Each of these applications must be analyzed with a different approach-they cannot all be analyzed as variable-flow variable-pressure systems. This paper will review the three general types of applications which are seen for centrifugal pumps and suggest a method of implementing an energy savings program and analyzing each type of system.