Research On Tiny-Normal Power Combination Control Valve For Feedwater System

Steam generator water level impact on Steam quality in the two circuit directly, so the steam generator level needs to be kept on the number preestablish. The steam generator water level control depends on water level, feedwater flow, steam flow the three impulse method of regulating acts and they will control the feedwater control valve opening,and feedwater control valve is as a channel, the design of it is according to the maximum flow when the system goes on the max power demand. When feed water system goes in low power the measurement errors of steam flow and feed water flow are larger, but also the feedwater control valve is in small flow controlling on the larger channel, so when the system is in low power the control of steam generator water level cann’t be adjusted automatically and reliable; it is difficult to put the valve position signal into a feedwater level controller precisely, so limits the control strategy of the feedwater regulation; Feed water control valve works frequently, it is prone to over opening and clamping phenomenon. So, steam generator feedwater regulating is unstable and unreliable, and is not able to work automatic in low power condition by feedwater control valve. In order to solve the problem, the AP1000nuclear power plant system is designed two feed water control valves in the feed water regulation system, installed in parallel main water supply pipe and startup feedwater pipe.When the system works in high power, the main feedwater control valve is put into use; When the system works in low power, the start-up feedwater control valve is put into use. For the feed water system in ships and warships, it also can be design as that in principle but the emergence of new issues is that it needs to provide larger installation space,and for marine nuclear power such conditions are difficult to provide. Use the tiny-normal power regulating valve and a programmable control technology to change the now feedwater control valve and excogitate a simple control system to realize the steam generator water level can be automatic, accurate, reliable controlled when the system working in a low power, ensure the plant reliable and safe, crew life safety, save a lot of repair funds. This paper introduces comprehensively on the control valve flow characteristics, strength calculation of the main parts, the flow coefficient calculation, focuses on tiny-normal power combination control valve for Feedwater System and make an intensive study of the valve on structure, working principle, flow characteristics choice, strength calculation of the main parts of flow coefficient.It can show us how to design satisfied,performance requirements, safe and reliable feedwater control valve.