Cooling limitations in power plants: Optimal multiperiod design of natural draft cooling towers

In this work we evaluate the effect of weather and cooling towers location on its size and monthly operation by developing a multiperiod optimization formulation aiming at minimum water consumption. Coal based and CSP plants are considered. While the operation of both depends on the weather, CSP plants operation is also characterized by non steady production of energy that also depends on weather conditions. Furthermore, a CHEMCAD simulation is also put together to evaluate the limits in power production as a result of the cooling capabilities in different climates. The mathematical formulation shows that the driving force is limited in winter and that the extreme temperatures of summer reduce the production capacity of the plant due to limitations in the heat transfer capacity. Colder climates require larger towers but show lower water consumption. Hotter climates need additional heat transfer area. It comes a point when the efficiency of the Rankine cycle and, as a result, the power production must decrease by increasing the exhaust pressure of the low pressure turbine so as to be able to refrigerate the system.