Energy Savings Potential of Process Control Valve Replacement

Abstract

A review of current design methods for industrial process control systems that utilize modulated control valves as their final element is presented. The infornUltion that is available is then used to find the theoretic potential for energy savings in these systems. Energy savings potentials vary with the application. This paper will concentrate on the application ofvariable speed drives on common three phase AC induction motors as a replacement final element to realize the energy savings, but will also address other possible solutions for partial energy cost recovery. Since the theoretic potential savings is not always the practical case, a set of guidelines for the application ofthis data is proposed that would allow the user to more easily locate candidates for savings. A feasibility study of retrofitting a pipeline flow control system, currently operating with a constant speed pump and differential producing, modulating control valve, with a variable speed drive is presented. This case study is considered with the system data ofan actual pipeline as well as valve and pump curves of installed equipment. The annual energy savings available by retrofitting is considered in addition to the payback period for the variable speed drive.