Research on enhancing power plant net power by integrating modeling heat transfer and operation optimization of once-through cooling water system

For low power generation efficiency and water source thermal pollution caused by irrational operation of once-through cooling water systems (OCWSs) in condensing power plants, this paper advances a method to maximize the power plant net power by OCWS operation optimization and a 2 × 330 MW power plant is taken as a study case. First, the power plant thermodynamic system is simulated by Ebsilon to obtain exhausted steam parameters. Then, a heat transfer analysis method for the whole OCWS is investigated to calculate the system water temperature. Next, a maximum net power optimization model is deduced and established. Particularly, the model sets the temperature difference between OCWS outlet and inlet as a constraint. Finally, an improved firefly algorithm is employed to solve the model to get the numbers of constant-speed pumps and variable-speed pumps in operation and the frequency conversion ratio of the latter. This paper analyses the optimization under various scenarios and the sensitivity of optimization results. After optimization, the net power of the case power plant is increased up to 2080.5 kW, approximately 0.524 %. The OCWS temperature difference is decreased under most conditions. The method effectively enhances power plant net power and reduces drainage impact on the environment.