Turbine Protection Device

Abstract

An object of the present invention is to provide a turbine protection device which can interrupt backflow from a deaerator to a turbine completely even if a check valve provided between the deaerator and the turbine can not interrupt the steam flow between the deaerator and the turbine completely. In order to achieve the above object, a control unit sends commands to a shutdown valve device so as to close the shutdown valve device when a differential pressure resulted from subtracting a pressure of a extraction steam from a pressure within the deaerator becomes greater than or equal to a first predetermined value. As a result, the backflow from the deaerator to the turbine is interrupted by a stop valve of the shutdown valve device.

1 . A turbine protection device provided in a steam turbine system, the steam turbine system comprising:
 a turbine driven by steam generated in a boiler;   a condenser to condense the steam exhausted from the turbine into a condensate;   a deaerator to store the condensate which is preheated by being heated and deaerated;   an inlet pipe to take the extraction steam for heating and deaerating into the deaerator; and   a check valve provided in the inlet pipe, comprising:   pressure gauge to measure pressure of the extraction steam and pressure within the deaerator;   a shutdown valve device provided in the inlet pipe; and   control unit to control the shutdown valve device using commands based on the pressure of the extraction steam and the pressure within the deaerator,   wherein the shutdown valve device is opened and closed by the commands from the control unit, and when the shutdown valve device is closed, the shutdown valve device interrupts the steam flow from the deaerator to the turbine.   
     
     
         2 . The turbine protection device according to  claim 1 , wherein the control unit
 sends commands to the shutdown valve device so as to close the shutdown valve device when a differential pressure resulted from subtracting the pressure of the extraction steam from the pressure within the deaerator becomes greater than or equal to a first predetermined value which is set in advance, and   sends commands to the shutdown valve device so as to open the shutdown valve device when the differential pressure becomes greater than or equal to a second predetermined value which is set in advance.   
     
     
         3 . The turbine protection device according to  claim 1 , wherein the control unit
 sends commands to the shutdown valve device so as to close the shutdown valve device when a first predetermined time has elapsed on condition that a differential pressure resulted from subtracting the pressure of the extraction steam from the pressure within the deaerator is greater than or equal to a first predetermined value which is set in advance after the differential pressure becomes greater than or equal to the first predetermined value, and   sends commands to the shutdown valve device so as to open the shutdown valve device when a second predetermined time has elapsed on condition that the differential pressure is less than or equal to a second predetermined value which is set in advance after the differential pressure becomes less than or equal to the second predetermined value.   
     
     
         4 . A method for controlling a steam turbine system, the steam turbine system comprising:
 a turbine driven by steam generated in a boiler;   a condenser to condense the steam exhausted from the turbine into a condensate;   a deaerator to store the condensate which is prepared by being heated and deaerated;   an inlet pipe to take the extraction steam for heating and deaerating into the deaerator; and   a check valve provided in the inlet pipe, comprising the steps of:   measuring a pressure of the extraction steam and a pressure within the deaerator;   opening and closing a shutdown valve device provided in the inlet pipe based on a differential pressure between a pressure of the extraction steam and a pressure within the deaerator; and   interrupting the steam flow from the deaerator to the turbine by closing the shutdown valve device.   
     
     
         5 . The method according to  claim 4 , wherein further comprising the steps of:
 sending commands to the shutdown valve device so as to close the shutdown valve device when a differential pressure resulted from subtracting the pressure of the extraction steam from the pressure within the deaerator becomes greater than or equal to a first predetermined value which is set in advance, and   sending commands to the shutdown valve device so as to open the shutdown valve device when the differential pressure becomes greater than or equal to a second predetermined value which is set in advance.   
     
     
         6 . The method according to  claim 4 , wherein further comprising the steps of:
 sending commands to the shutdown valve device so as to close the shutdown valve device when a first predetermined time has elapsed on condition that a differential pressure resulted from subtracting the pressure of the extraction steam from the pressure within the deaerator is greater than or equal to a first predetermined value which is set in advance after the differential pressure becomes equal to or greater than or equal to the first predetermined value, and   sending commands to the shutdown valve device so as to open the shutdown valve device when a second predetermined time has elapsed on condition that the differential pressure is less than or equal to a second predetermined value which is set in advance after the differential pressure becomes less than or equal to the second predetermined value.