Energy reduction for a dual circuit cooling water system using advanced regulatory control

摘要

Various process utilities are used in the petrochemical industry as auxiliary variables to facilitate theaddition/removal of energy to/from the process, power process equipment and inhibit unwanted reaction.Optimisation activities usually focus on the process itself or on the utility consumption thoughthe generation and distribution of these utilities are often overlooked in this regard. Many utilities areprepared or generated far from the process plant and have to be transported or transmitted, giving riseto more losses and potential inefficiencies. To illustrate the potential benefit of utility optimisation, thispaper explores the control of a dual circuit cooling water system with focus on energy reduction subjectprocess constraints. This is accomplished through the development of an advanced regulatory control(ARC) and switching strategy which does not require the development of a system model, only rudimentaryknowledge of the behaviour of the process and system constraints. The novelty of this manuscriptlies in the fact that it demonstrates that significant energy savings can be obtained by applying ARC toa process utility containing both discrete and continuous dynamics. Furthermore, the proposed ARC strategydoes not require a plant model, uses only existing plant equipment, and can be implemented on controlsystem hardware commonly used in industry. The simulation results indicate energy saving potentialin the region of 30% on the system under investigation.