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.

Abstract: A waste heat recovery boiler system has a plurality of waste heat recovery boilers each having a main steam generator and a reheater capable of generating main steam and reheat steam by heat derived from a hot waste gas introduced into the waste heat recovery boiler. The flows of main steam from the main steam generators are joined to form a single flow of main steam to be used in an external installation, and the flows of reheat steam from the reheaters are joined to form a single flow of reheat steam to be used in the external installation. The steam discharged from the external installation is distributed to the reheaters. Flow rate controllers are provided for controlling the flow rates of the steam through the reheaters in relation to the hot waste gas supplied to the respective waste heat recovery boilers.

Abstract: Apparatus and method of monitoring the performance of a steam power plant, wherein the monitoring is made through a calculation of the performance from detected data representing the states of operation of various parts of the plant, such as feedwater flow rate, steam pressure, steam temperature and the level of the load imposed on the plant. The method has a function for judging the fluctuation of the load and a function for judging the duration of steady state of the load. When the rate of fluctuation of the load is below a predetermined reference and this state of load lasts over a predetermined time length, it is judged that the data detected during this time length are valid as the data for monitoring of the performance and the performance is calculated from these data to permit the monitoring.