Abstract: Liquid injection into the interstage steam flow in a multi-stage compressor is controlled by calculating a saturation temperature of the fluid in the interstage and then controlling the liquid flow to reduce the incoming fluid temperature to a value a predetermined amount above the saturation temperature. In one embodiment, the fluid temperature is measured at the downstream end of the interstage conduit after it has been reduced by liquid injection. This measured temperature is used to compare with the calculated saturation temperature to determine whether to increase or decrease the liquid injection flow. In another embodiment of the invention, the fluid temperature is measured upstream of the liquid injection point.

Abstract: Keybars for affixing stator core laminations to annular web plates of a stator frame include a cylindrical portion and a dovetail portion. The cylindrical portion is closely fitted within accurately bored axially aligned circular holes in the annular web plates. During preliminary assembly, the cylindrical portions of the keybars are inserted into the aligned bored cylindrical holes in the annular web plates with the dovetail portions facing radially inward. Due to the accuracy with which the bored cylindrical holes are positioned, chordal positioning of the keybars prior to welding is achieved with a jig positionable between adjacent keybars. During welding, the keybars are pulled radially inward to place all clearances between the circular portions and the bored cylindrical holes radially outward of the cylindrical portion.

Abstract: In a dynamoelectric machine, the rotor comprises a solid steel drum formed with axially extending channels which carry electrically-conductive windings. These windings are electrically insulated from the rotor body by so-called slot insulation. The present invention proposes an integrally formed composite insulation comprising aramid paper slot armor and an epoxy-glass sub-slot cover.

Abstract: A heat exchanger includes a number of fluid carrying tubes disposed in a hot gas flow path. One arrangement of heat exchanger tubes includes a plurality of finned serpentine tubes parallel to one another and connected to an inlet header and an outlet header. The present invention discloses a support for a serpentine tube arrangement and a method of construction for a non-contact heat exchanger.

Abstract: A coupling between two shafts surrounded by a coupling guard seal assembly to prevent the leakage of fluid from out of the coupling. The coupling guard includes two coaxial closed overlapping surfaces otherwise described as inner and outer cylinders. The inner surface is formed with a groove which contains an annular gasket and notched ring. The outer surface includes circumferentially spaced apart slots which when aligned with the notches provide key ways for cam pins. When assembled the cam pins are each locked against the notched ring causing the "O" ring to elongate in the radial direction to provide an improved seal.

Abstract: Blades in the steam path of a steam turbine diaphragm are assembled into slots in full circular bands and are structurally bonded thereto by welding. After stress relief, the bands are each separated into two 180 degree pieces by line cuts which pass between adjacent blades. The bands are then welded to semicircular rings having planar mating surfaces. The welding of the rings to the bands is performed with minimum welding without concern for whether the welds enter the interface sufficiently far to contact the blades themselves.

Abstract: A test apparatus and method tests for closure of ganged, cam operated main control valves in a steam turbine. Cam actuation of a set of upper main control valves is separated from cam actuation of a lower set of main control valves. A test controller actuates one of the sets of main control valves in the opening or closing direction and holds the other set stationary while monitoring turbine power output. When the power output has changed by a predetermined amount, the test controller halts actuation of the first-actuated set of main control valves and begins actuating the other set of main control valves in the opposite direction until the turbine power output has changed a predetermined amount in the opposite direction. The process of incrementally closing one set while incrementally opening the other set of main control valves is continued until the set of main control valves being moved in the closing direction should be fully closed.

Abstract: Primary and secondary controllers both receive independent digital representations of shaft speed. Only one of the outputs of the two controllers is used. In order to detect a fault and isolate it to one of the two controllers, comparison is performed on the response of each controller with the response of the other controller. In addition, the response of each controller is compared with a system mathematical model which predicts the response which each controller should provide to a given set of inputs. If the first comparison indicates that one of the controllers is bad, the comparison with the system mathematical model identifies the faulty controller and provides a signal which removes it from operation and enables the good controller to begin providing control signals.

Abstract: A steam generation system employing a flash tank feeding low-pressure steam to a compressor controls surges in the compressor by calculating the amount of steam generated based on the temperature change and flow of water passing through the flash tank and modulates the flow rate in order to maintain the steam flow above a surge limit. If increasing the water flow rate is incapable of producing enough steam to avoid surges, a recycle control recycles steam from the output of the compressor back to the flash tank. A further embodiment of the invention permits using an auxiliary source of low-pressure steam to augment the steam produced in the flash tank while maintaining the total steam flow at a level sufficient to avoid surges. The steam flow may alternatively be derived from the differential pressure between outlet and inlet of the compressor.

Abstract: Outputs of two independent controllers are available to control a valve actuator in a turbine control system. One of these valve drive signals is applied to the valve actuator while the other is applied to a termination. When a fault is detected in the active controller, the secondary controller is reinitialized to eliminate any drift which may have occurred therein to provide a valve drive signal closely equal to a valve drive signal previously provided by the active controller. Switchover is performed placing the previously inactive controller in the active condition and applying the signal from the previously active controller to the termination.

Abstract: A digital shaft speed sensor modifies a clock frequency and counting period to provide a speed signal having wide dynamic range with adequate resolution. The division ratio of a programmable divider counting pulses from a shaft encoder is modified by a central processing unit based on the count or speed measured in a preceding counting. The output of the programmable divider sets an interval during which clock pulses are counted to determine the shaft speed. Since the dividing ratio of the programmable divider is dynamically changed according to previous speed measurements, the total number of clock pulses is correspondingly changed. In addition, the output frequency of the clock pulses is changed so that, at low speed, a low clock frequency can be used and at higher speeds, one or more higher clock frequencies can be used to maintain resolution with reasonable memory size.

Abstract: A steam pressure rate limiter for a steam turbine system reduces the setting of a steam control valve when a rate of decrease in steam pressure is detected which exceeds a threshold value of rate of decrease. A floor on control of the steam control valve is enforced in order to maintain a predetermined amount of steam flow to the turbine thereby to provide for cooling of the turbine.

Abstract: An overspeed detection circuit for producing an overspeed trip signal for shutting off a supply of motive fluid to a prime mover upon the prime mover exceeding an overspeed trip limit includes a differentiating circuit effective to differentiate a speed signal to produce an acceleration signal related to the rate of change in the speed signal. The acceleration signal is summed with the speed signal to produce an effective speed signal which anticipates the crossing of an overspeed threshold when a fault permits a constant speed increase to occur but does not force the summed signal to cross the overspeed threshold when normal speed control is exercised.

Abstract: A steam and gas turbine (STAG) plant employs a catalyst in a heat recovery steam generator to react injected ammonia with NO.sub.x from the combustor of the gas turbine to reduce atmospheric emission of NO.sub.x from the system. Rapid control of ammonia injection is achieved using a prediction of the NO.sub.x being generated in dependence upon the operating conditions of the combustor. A trimming signal from a measurement of NO.sub.x being emitted from the heat recovery steam generator downstream of the catalyst is employed to complete the NO.sub.x control loop.

Abstract: A steam and gas turbine combined cycle plant STAG* employs a catalyst in a heat recovery steam generator to react injected ammonia with NO.sub.x from the combustor of the gas turbine to reduce atmospheric emission of NO.sub.x from the system. Rapid control of ammonia injection is achieved using a prediction of the NO.sub.x being generated in dependence upon the operating conditions of the combustor. A trimming signal from a measurement of NO.sub.x being emitted from the heat recovery steam generator downstream of the catalyst is employed to complete the NO.sub.x control loop. Compensation is provided to relate the measured NO.sub.x downstream of the catalyst with the NO.sub.x in the output of the gas turbine taking into account the catalyst efficiency.

Abstract: In the control of prime movers, automatic and manually generated input signals should be able to be entered into the control system without undue control disturbance or perturbation. Likewise should an automatic signal fail, the switch to a last valid signal prior to entry into a manual mode is also desirable. An analog-digital hybrid circuit is described which includes a memory, storage, timing and manual input portions as well as certain select A or B circuits which allow for bumpless transfer between automatic manual and memory modes of operation.

Abstract: A stator wedge assembly provides a spring force to assist in retaining a conductor securely in a slot, without requiring a separate spring. Two ends of the assembly are received in a dove-tail at the mouth of a slot. A central spring section extends between the two ends and is slightly narrower than the walls at the mouth of the slot, so that it is free to flex. The central part of the central spring section has an increased thickness extending towards the conductor in the slot. At least one wedge is inserted, to press against the conductor in the slot on one side and to press against at least one of the two ends and the central part of the central spring section on the other side, forcing the central spring section away from the conductor. Because of the flexibility or springiness of the material of the flexed central spring section, a spring force is applied to assist in restraining the conductor in the slot.

Abstract: A control system for a prime mover may include a proportional speed control, a primary overspeed control and an emergency overspeed control. The proportional speed signal is obtained from select highest value logic, whereas overspeed and loss of speed signals are submitted to two out of three logic and two out of four logic, respectively. A passive emergency overspeed channel is provided in combination with the primary overspeed channel to respective de-energize and energize trip relays connected to electrohydraulic trip devices.

Abstract: In a dynamoelectric machine having a rotating field and a stationary stator core, electrical conductors are contained within axially-extending radial slots which are part of the stator core construction. These electrical conductors are subject to electromagnetic forces and thermal cycling effects which, over a period of time, tend to cause the electrical conductors to become loose within their slots. A system of wedges is used to retain these electrical conductors in place and in particular a dovetail wedge is used in combination with a mating surface in a stator slot.

Abstract: A method of and apparatus for controlling a steam turbine system for a combined cycle power plant using measured parameters to control the position of dampers regulating heat flow to steam generating equipment so as to limit thermal stresses, drum level surge and to provide load-following capabilities.