More Efficient Heat Recovery from the Condensate of Reheaters at New and Operating Nuclear Power Plants (NPPs)

A variety of technical solutions for the design arrangements of systems of turbine units (TU) at NPPs is the result of ongoing search for ways to increase the efficiency of electricity generation. A critical element of NPP TU systems, which has a pronounced effect on the efficiency and reliability of the power unit, is the steam separation and reheat (SRH) system. Therefore, this system should have an optimal list and structure of the employed equipment. The Russian and global experience in the design and operation of NPP TUs has demonstrated that the high-potential flow of heating steam condensate (HSC) of the secondary reheater of the SRH system can be utilized using three methods: by gravity into the last high-pressure heater in the feedwater flow, into a special condensate cooler, and by pumping into the feedwater path. These methods differ in thermal efficiency, cost, and performance indicators. The article compares the feedwater heating processes for various options of the heat recovery of the high-potential HSC flow from the steam reheaters of NPP turbine units. A feasibility study of their effectiveness has been performed, taking into account the net power of the turbine unit, the specific of the employed equipment, experience in its design and operation, and price characteristics. Recommendations are prepared on the selection of a system for heat recovery of HSC from the secondary reheater and on the type of equipment used. For operating NPPs with low-speed TUs, a conceptual proposal was developed to increase the net electric power by up to 1.6 MW by the installation of a water-jet ejector for pumping the HSC from the secondary reheater into the feedwater path.