Research On Simulation Modeling And Vacuum Control Of The Marine Condenser

The steam is taken as a working medium in marine nuclear-powered steam turbine,it can do work while expanding,its thermal energy is transformed into mechanical energy,which is used to generate the power of ship.The condenser receives exhaust steam of the turbine and the bypass system,condenses steam into water,and maintains back pressure which the turbine operation needs.The ship changes its velocity by varying the rotary speed of the steam turbine,exhaust flow changes,which causes the change of working conditions,and the condenser pressure also changes,which affects the work efficiency of the turbine and the stable operation of the condenser.Different from the ships on the sea,nuclear submarine can sail underwater,it moves up and down as required,the temperature of the seawater outside is changing constantly,which affects the operation pressure of the condenser.So we should control the vacuum of the marine condenser under ocean conditions,in order to maintain the stable operation of the secondary loop.The condenser of marine nuclear power plant is studied in this paper.The exhaust steam of the main turbine is condensed into water by the cooling water in the condenser,and gathering in the hot well at the bottom,the circulate cooling water in the pipes heat up by absorbing the heat released.According to the physical phenomena and the heat transport,the condenser is divided into three regions,the mass conservation equation,energy conservation equation,flow equation and heat transfer equation are described in every region by using lumped parameter method,we can calculate vacuum degree by solving these equations simultaneously,the condenser mathematical model is built.Based on the mathematic model,the simulation model of the marine nuclear power plant condenser is built.The simulation results show that,the pressure of the condenser is below the limits value when the steam flow and the temperature of the cooling water change a lot,the simulation model has good static characteristics.The dynamic simulations are tested in the variable conditions,such as the exhaust steam and the seawater temperature change rapidly,the results show that dynamic changes of all parameters are in accordance with objective rules,the simulation model can be used to make vacuum control method research.The condenser has the corresponding best operating pressure under various working conditions because of economic reasons,when the boundary conditions change,the vacuum degree can be controlled to be stable at the best one.This paper studies the PID control methods of condenser vacuum in different conditions,such as steam flow and seawater temperature change substantially and rapidly,normal control methods have high overshoots,so we combine the single neural self-adaptive control,the fuzzy RBF network control with normal PID control.The simulation results show that two control methods improved the overshoot and response speed compared with the traditional PID control.Several feasible plans for the control of the condenser pressure are provide in this paper.