Hitachi, Ltd.

Naganobu Honda

Yasuhiro Tennichi

Seiitsu Nigawara

Akira Sugano

Hisanori Miyagaki

Atsushi Takita

Sadao Yanada

Yurio Eki

An apparatus for controlling the drum water level of a drum boiler prevents the boiler system from being tripped off which would otherwise be caused by an excessive fall in the drum water level immediately after the start of load runback, by increasing the real feed water flow rate in such a manner that a feed water flow rate demand signal obtained from the drum water level deviation is corrected by a feed water flow rate increment signal obtained from the amount of load reduction (load demand--load reference after load runback) at the time of load runback. In addition, the fact that the drum water level stops falling and starts to rise is detected, and the feed water flow rate demand signal is adjusted so as to take a medium value between the real feed water flow rate and the real main steam flow rate, thereby preventing the boiler system from being tripped off which would otherwise be caused by an excessive rise in the drum water level.

Apparatus for controlling drum water level of drum type boiler

A method of controlling the operation of a thermoelectric power generating plant, in which the operation of the steam generating equipment and the turbine is controlled in accordance with the plant operation parameters obtained from given patterns of start up and operation of the plant. The method comprises: temporarily setting, in accordance with the above-mentioned patterns, the plant operation parameters concerning the rates of change of state of the plant such as the rates of turbine acceleration and turbine load and rates of increase of the main steam temperature and pressure; estimating the change of the quantity of state of main steam at a designated future moment; estimating the thermal stresses in respective stress-evaluation portions of the boiler and turbine; comparing the estimated thermal stresses with respective allowable thermal stresses determined so as to correspond to the consumption of the life allowed for each start up and operation cycle of the plant; selecting one of the estimated thermal stresses which has smaller margin to the allowable thermal stress and obtaining the operation parameter which provided the maximum rate of change of the state of the plant; repeating these steps until the command state is attained; and controlling the boiler and the turbine in accordance with the thus obtained plant operation parameter.

Method of controlling operation of thermoelectric power station

In a steam turbine used with a power plant operated under variable pressure of the steam which is fed to the turbine through control valves, the control apparatus is arranged to control the control valves according to a signal obtained by adding an opening set signal with a compensation signal which is determined in dependence on a difference between a turbine stage steam pressure signal and a signal derived by multiplying the opening set signal with a ratio of the actual value of the control valve inlet steam pressure to a rated value thereof.

Control apparatus for steam turbine

An electro-hydraulic governer employing a duplex digital controller system for the optimum speed control of a steam turbine running with increasing speed in the starting stage or under load. Each of the digital controllers is operable with both a control mode and a stand-by mode, and when one of the digital controllers is placed in the control mode for controlling the rotating speed of the turbine, the other is placed in the stand-by mode to prepare for possible failure of the controller operating with the control mode. A failure detecting unit detects failure of the digital controller operating with the control mode. An output switching unit disconnects the faulty digital controller from the control system and switches over the operating mode of the stand-by digital controller from the stand-by mode to the control mode for the continuous control of the rotating speed of the turbine. A display is provided on an operator's console to display the outputs of these two digital controllers, and the faulty digital controller is detected by non-coincidence of the displayed information. The faulty digital controller having been disconnected from the control system by the output switching unit is repaired as quickly as possible, and after necessary repair, it stands by to prepare for possible failure of the other controller operating with the control mode.

Growing community of inventors

Hitachi, Japan

Naganobu Honda