Determining the Optimum Pressure Differential Across the Control Valve of a Hydroturbine Driven Pump

Abstract

When using lead as a primary circuit coolant, certain difficulties arise not only from the side of the reactor plant (structural materials, fuel, etc.) but also from the side of the steam turbine cycle. A feature of the second circuit of a lead-cooled NPP is noted, such as the need to maintain a high temperature of the feedwater in front of the steam generator, caused by its melting/freezing temperature. For the pilot demonstration power unit with the BREST-OD-300 reactor plant, it was decided to use a mixing feedwater heater, which entailed the appearance of a second rise in the feed pump circuit. Due to the lack of electric drive pumps for such high parameters, it was proposed to use a hydraulic turbine driven pump as a feed pump behind the mixing feedwater heater. These pumps have a significant impact on efficiency due to the multistage energy conversion, and there is no recommendation for selecting resistance on the control valve of these pumps. A computational study was carried out to determine the optimal pressure drop on the control valve of the hydraulic turbine drive of the feed pump of the power unit with the BREST-OD-300 reactor plant. Optimal is understood as the ultimate minimum differential at which the valve is able to carry out regulation with specified quality criteria and ensure the lowest energy consumption for its own needs. Recommendations are given for choosing the optimal pressure drop on the control valve of the hydraulic turbine drive of the feed pump of a turbine unit with the BREST-OD-300 reactor. A methodology has been developed for solving problems of optimizing pressure drop in units of complex hydraulic systems.