Chlorine use reduction in nuclear or conventional power plants: a combined cooling-and-stripping tower for coastal power plants

Abstract

Conventional seaside nuclear or coal-fired power stations draw water directly from the sea, chlorinate it and send it into a “once-through” cooling circuit that discharges it directly back into the sea. This practice leads to a constant input of thermal and chemical pollution (residual chlorine and chlorination by-products) into ecosystems in the immediate vicinity of the power plant. To reduce chlorine usage and achieve a cleaner process, a new design for the cooling system of power plants is proposed. This can be accomplished by means of a cooling-stripping tower that operates in a closed circuit. With that purpose in mind, the design of such a cooling system configuration was undertaken. Results show that the warm stream leaving the condensers at 38°C cools down to 27.1°C after exiting the cooling-stripping tower. This decrease in the seawater coolant temperature before it is rejected to the sea therefore prevents thermal pollution. Furthermore, the small amount of seawater returned to the sea at 27.1°C contains no chlorination by-products. In addition, a dramatic reduction in the seawater intake by the cooling system is obtained, and represents only 5.2% of that needed by conventional systems. This, in turn, implies a reduction in the chlorine dosage and the filter sizes required for the seawater input stream. It is recommended that all power plants consider implementing the proposed design in order to prevent seawater pollution and damage to coastal ecosystems.