Optimization of Operating Parameters of Open Cooling Towers of the Double-Circuit Cooling System

Abstract

The operation of most chemical processes is accompanied by the cooling of various production streams over a wide temperature range using various refrigerants. At cooling temperatures of process streams up to 25 °C, the most common refrigerant is water prepared in circulating water supply systems of petrochemical plants equipped with fan cooling towers, the work of which is considered in the article. Operation of open cooling towers in single-circuit cooling systems is characterized by high economic efficiency with a wide range of thermal capacities. However, drip entrainment of circulating water, entry of production products into the atmosphere, enrichment of circulating water with oxygen followed by growth of microorganisms in water requires a transition to two-circuit systems in which cooling is carried out by a closed-cycle refrigerant cooled by open-cycle water passing through cooling towers. But such changes in cooling systems reduce the economic efficiency of these systems. The analysis of the equipment operation in the open and closed circuits of the cooling system, provided that a number of system parameters are constant (heat load, quality of purification of recuperation heat exchangers of the cooling system, etc.), made it possible to formulate optimization (minimization) of operating costs for water cooling. Taking into account the previously obtained models of pollution growth in recuperation heat exchangers and considering the vector of control parameters of the optimization problem, the main parameter of optimization (mimimization) of operating costs for cooling, which is the cooling temperature of cooling water, was identified. The results of the analysis of the influence of ambient air parameters on the temperature of the produced cooling water in the open cooling towers are also presented, and the calculation of the economic efficiency of the cooling system operation is carried out taking into account seasonal changes in ambient air parameters.