Cooling Water System Modelling for Control and Energy Optimisation Purposes

Utilities account for a significant portion of the fixed cost associated with running a petrochemical plant, however, utility optimisation has not received much focus until recently. This change was driven by rising energy prices, stricter environmental policies, and the threat of climate change. Several utilities are used including steam, compressed air, nitrogen, cooling water, refrigeration water, tempered water, electricity, and fuel gas. Generation and preparation of all of these utilities require energy and therefore merits optimisation to reduce waste. This paper describes the modelling of a dual circuit cooling water system containing a combination of discrete and continuous energy components for control and energy optimisation purposes.