SWITCHING METHOD OF STEAM PRESSURE CONTROL SYSTEM OF TURBINE GLAND SEAL

摘要

PURPOSE:To prevent variation of steam pressure, in a system in which sealing of the gland part is performed by the use of a steam pressure control system with difference at the time of starting from the time of normal operation, by switching the control system while monitoring deviation of the sensed value of sealing steam pressure from the corresponding set value. CONSTITUTION:At the time of starting, a motor-driven valve 15 on the steam pressure evaporator-generated control system provided in the plant is opened, while a motor- driven valve 12 on the steam pressure control system is closed, and a pressure regulator valve 14 is opened gradually in compliance with the output signal of a program setting device 5 selected by a switcher 8. At this time, the gland sealing steam pressure is sensed by a pressure conduction device 1, and the deviation of the sensed value from its corresponding set value is determined at a deviation calculator 2 while monitoring it by a monitor 3. When the deviation has become zero, the abovementioned switcher 8 shall select a proportional integral operator 4, and the output therefrom shall serve control of the abovementioned regulator valve 14. Switching to the normal operation side is made by opening first the valve 12, and then closing the pressure regulator valve 14 while another pressure regulator valve 11 is opened gradually by the output of a program setting device 6 selected by the switcher 8.