Control of Water Flow in Cooling of Thermal Power Plants

Abstract

The water flow rate of the cooling system of tower cooling towers is considered as a controlled parameter. Using data on the irregularity of irrigation density over the cross-section, a regression model of the operating characteristic of a tower cooling tower was obtained, which establishes the dependence of the temperature difference on the irrigation density. Based on this characteristic, the existence of an extremum of the cooling capacity of the cooling tower in terms of the flow rate of the flow is established. A mathematical analysis of the circulation flow control using shutoff valves in a single-circuit water supply system is carried out. The equation of the relationship between the flow rate of the circulating flow and the control position of the shutoff valves is given. An energy-saving method for controlling the performance of a circulation pump using frequency regulation is considered. A mathematical model of the hydrodynamics of the circulation circuit is constructed that describes the dependence of the circulation flow on the parameters of the shutoff valves and/or the frequency controller of the pump drive. A system for automatically controlling the vacuum in the condenser of a steam turbine plant is proposed. The circulation flow can serve as an optimizing and controlling parameter of the cooling capacity of the system. The developed mathematical model of a circulating system controlled by a frequency regulator of an electric drive of a circulation pump and/or shutoff valves of heat exchangers is recommended for use in solving the design and control problems of a circulating system. In automated process control systems, it can be used both for calculating the cooling capacity and unit energy consumption and in combination with regulation laws for flow control. This will improve the quality of the transition process, and, consequently, increase the efficiency and safety of production.