Westinghouse Electric Corporation

Foster Wheeler Energy Corporation

Morton H Binstock

Leaman B Podolsky

Thomas H McCloskey

Steven J Johnson

Robert Lenox Criswell

Walter B Shaltes

Bertram H Stern

Robert C Lehmer

John J Topolosky

Thomas E Smith

A method and apparatus for controlling the operation of a steam turbine system, which system includes a source of steam under a controllable pressure, a plurality of governor valves connected between the source and the turbine first stage, each governor valve being movable between two selected positions each creating minimum steam flow throttling losses, a system control device (2) for producing a system control signal representative of the desired power level to be supplied by the turbine system, and a governor valve control (8) connected for producing a valve control signal in response to an input signal and for positioning each governor valve in accordance with the value of the valve control signal. During operation, the input signal to the governor valve control (8) is given a value which is based on the system control signal and which causes the valve control signal to have a value which will place each governor valve at least approximately at a selected position. In order to position the governor valves more accurately, the rate of flow of steam from the steam source is measured (18); the difference between the measured rate of flow and the expected rate of flow of steam from the steam source is determined (20, 24); and the value of the input signal to the governor valve control is modified (6, 12) in response to the difference determined in a direction to vary the positions of the governor valves in a manner to reduce the magnitude of that difference.

Turbine efficient valve position computer

A bypass system for a steam turbine wherein the energy level of the steam bypassed around the intermediate pressure and low pressure turbines is modified by introduction of cooling water. The amount of water introduced is adaptively varied as a function of the enthalpy of the bypassed steam as measured by a sensor in the steam path.

Turbine low pressure bypass spray valve control system and method

A DEH (digital electrohydraulic) control system for a steam turbine generator having a steam bypass system. The turbine system includes a high pressure turbine having throttle and governor steam admission valves as well as an intermediate pressure turbine having stop and interceptor steam admission valves. The turbine is brought on line by initially controlling steam admission into the intermediate pressure turbine by modulating the interceptor valve in response to a speed error signal generated as a result of the difference between actual and a predetermined reference speed. During this initial control the throttle valve remains in a closed position. When the turbine speed has attained a preset value such as half of synchronous speed, the interceptor valve is held at the same position it was in when the preset speed was attained and the throttle valve is controllably open in response to the same speed error signal. After a preset transfer speed has been attained, control of steam admission to the high pressure turbine is transferred to the governor valve and after synchronous speed has been reached the DEH system switches to a load control mode wherein the signal which controls the positioning of the governor valve is also utilized to control the interceptor valve position. The interceptor valve thereafter will reach a wide open position at a predetermined load. During the speed control mode of operation the control signal which controls the positioning of the interceptor valve is modified by certain pressure conditions at the input of the interceptor valve after the preset speed is attained.

Control system and method for a steam turbine having a steam bypass

A bypass system for a steam turbine wherein the temperature of the steam bypassed around the high pressure turbine is accurately controlled by measuring the inlet and outlet temperatures of the boiler reheater and generating an adaptive set point. The set point value is used to govern operation of a spray valve which admits cooling water to the bypass steam path.

Turbine high pressure bypass temperature control system and method

A steam turbine system which includes a steam generator and a steam bypass path for bypassing steam around the turbine. The outlet throttle pressure of the steam generator is controlled by controlling admission of steam into the bypass path by means of a bypass valve. A desired throttle pressure set point is generated which is independent of steam flow and this set point is compared with the actual throttle pressure for governing the bypass valve during turbine start-up. When the turbine is fully operational the bypass valve control is effected by a comparison of the actual throttle pressure with the desired throttle pressure set point plus some bias.

Turbine high pressure bypass pressure control system

A steam blending control is provided for two or more boilers in an electric power plant. To blend an oncoming boiler with an on-line boiler, the oncoming boiler is fired to a pressure ramp setpoint and outlet steam is isolated from the plant turbine and directed through position controlled bypass valve means. When steam temperature and pressure conditions are matched, the oncoming boiler isolation valve is opened and the bypass flow then existing is stored in a memory. The oncoming boiler bypass flow is cut back with total oncoming boiler steam flow controlled to the memorized flow valve as a setpoint. Flow from the on-line boiler is cut back under load control as the oncoming boiler flow to the plant turbine is increased. Deblending is implemented in a similar manner.

Multiple boiler steam blending control system for an electric power plant

An automatic control is provided for fast restarts of a hot power plant. Boiler fuel demand is increased to reach a target load based on measured turbine metal temperature and throttle pressure. Fine tuning of the fuel demand is performed to achieve an actual match between the turbine and steam temperatures. Turbine bypass valves are operated during boiler firing the control steam pressure to a programmed pressure setpoint. Boiler firing rate is high limited by total boiler outlet steam to avoid flow overheating and bypass valve position is low limited in accordance with steam flow and throttle pressure to avoid excessively low steam flow. Reheater controls are operated to match intermediate turbine temperature and reheat steam temperature.

Automatic restart control for a power plant boiler

In a power plant, a solid state sequence is provided for starting an FD or ID fan, or for changing the fan speed in response to the position of the fan inlet vanes. The sequential process is self-calibrated since process events control the stepping operation of the sequencer. At the operating fan speed, boiler air flow and pressure are controlled by fan inlet vane position in accordance with plant load demand. When the fan speed is changed, a multiplier circuit causes the fan inlet vanes to reposition so as to minimize air flow changes as the fan speed changes. When one of multiple FD fans or multiple ID fans has its speed changed at a time a fan balancer control, which normally equalizes air flow, is biased to permit different fan flows through the different speed FD or ID fans.

Coordinated control for power plant forced and induced draft fans during

An efficient valve position controller adapted for use in a steam turbine power plant for efficiently positioning a plurality of steam admission valves to substantially effect a desired power generation level is disclosed. The power plant includes a boiler for generating steam to the turbine at a boiler throttle pressure that is governed by a pressure set point; a valve control means which is governed by a reference signal corresponding to the desired power generation level to position the plurality of steam admission valves in a state according to a predetermined valve positioning pattern based on the value of the reference signal; and an electrical generator driven by the steam turbine to generate electrical energy. A plurality of values of the reference signal are predetermined as being related to efficient valve position states for regulating steam admission to the turbine. The controller adjusts the pressure set point at a desired rate and in a direction as determined by the difference between a selected one of the predetermined values and a present value of the reference signal. Accordingly, the reference signal is modulated as a function of the pressure set point adjustment until the reference signal is substantially equal to the selected value at which time the reference signal is governing the valves substantially at an efficient valve position state and further pressure set point adjustment is inhibited. In addition, when the reference signal becomes equal to a predetermined threshold value which is indicative of the steam admission valves being substantially wide open, the pressure set point is adjusted to a preset value.

Efficient valve position controller for use in a steam turbine power

The disclosed system detects the pressure rise across the fan and the flow rate in the system and integrates signals corresponding thereto, and outputs a signal to indicate to the user when the pressure rise exceeds a given level for a corresponding flow rate to warn of a condition within a given degree of a stall condition. The system outputs another signal to block any increase in fan blade pitch and substitutes a decrease pitch signal in response to a predetermined closer approach to a stall condition so that the pitch of the blades is reduced to a position in which the pressure rate rise and flow rate are reduced to a safe level with respect to a stall condition. The system also includes means responsive to the predetermined closer approach to stall to prevent the user from feeding a blade pitch increase signal following a reduction in the pressure rise across the fan until the user resets a bistable device.

Control system for variable pitch axial fan for utility boiler

A once-through boiler is provided with integral separators with which drain valves are associated. Boiler inlet and outlet flows are balanced throughout startup first by drain valve control in response to separator level and then by drain valve control in response to throttle pressure.

Flow control for once-through boiler having integral separators

A once-through boiler is provided with integral separators and a plurality of valves for controlling fluid flow during boiler startup. A pressure control generates an open or close signal for all of the valves and a sequence selector responds to the pressure control and a valve-in-operation logic circuit to generate valve selection signals which enable the valves to respond sequentially to the pressure control output.

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Pittsburgh, PA, United States of America

Morton H Binstock