General Electric Company

James H Moore

Jens Kure-Jensen

William I Rowen

Jatila Ranasinghe

Gregory Edward Cooper

Kenneth Elmer Robbins

Klaus Manfred Retzlaff

Sidney J Woodcock

Charles R Dumas

A variable loading rate method of starting a plurality of gas turbines (GT, GT) used in a combined cycle power plant for generating electricity. A first gas turbine is started and allowed to operate at a minimum load condition. The turbine is maintained at this load level while a second gas turbine is started brought up to its minimum load condition. Start-up of a steam turbine (ST) to which the gas turbines are operationally coupled is initiated while both gas turbines are maintained at their minimum load conditions. The load on both gas turbines is then increased to a predetermined level, which is greater than their minimum load levels, once operating temperatures within the steam turbine reach predetermined levels. Subsequently, both gas turbines are loaded as function of the load on the a steam turbine at to which the gas turbines are coupled. This variable loading rate starting sequence lowers the amount of NOproduced during start-up of the turbines and reduces the occurrence of a visible yellow plume at a power generating plant.

Start-up method for power plant

A combined cycle power plant includes at least two gas turbines driving two generators on respective first and second shafts; and a steam turbine having plural sections wherein one or more of the plural sections are on the first shaft and remaining sections of the plural sections are on the second shaft. A variation of the combined cycle power plant includes two gas turbines driving two generators on respective first and second shafts; and a steam turbine including high, intermediate, and low pressure sections on the second shaft.

Combined cycle power plant

A system and method for anticipating and controlling overspeed in a combined cycle turbine of the type having a gas turbine with a fuel flow control valve and a steam turbine with at least one steam control valve both disposed on a single shaft and having a heat recovery steam generator heated by said gas turbine and connected to supply steam to the steam control valve, the combined cycle turbine having a unified control system and driving a load. Below a preselected shaft speed the gas turbine fuel command signal controls power. Above the preselected shaft speed the steam turbine speed signal also controls power. Anticipation of overspeed under severe transient load changes, such as loss of electrical load, is provided by a power load unbalance system, wherein gas turbine power and steam turbine power responsive signals are summed after proportionately scaled power responsive signals exceed load by a preselected amount, whereby appropriate action is taken to reduce power before significant overspeed can occur.

Overspeed anticipation and control system for single shaft combined

A gas turbine is solidly coupled with rigid couplings in tandem with a reheat steam turbine and utilizes the combined inertia of the rotating members and the braking torque of the gas turbine air compressor to assist a single control system to limit overspeed of the complete unit. In its broadest and preferred form, the normal intercept steam valves and reheat stop valve between the reheater and the lower pressure steam turbine sections are eliminated, and the high pressure steam control valves are used to prevent overspeed, with steam flowing through a 'valveless' conduit from the reheater to the lower pressure steam turbine sections. The control system includes means for sensing a potential overspeed condition and operating the control valves to prevent overspeed. In a modified form of the invention a dump valve may be provided between the air compressor discharge and the combustion chamber of the gas turbine. In the modified form the control system will also open the dump valve, or the dump valve may open automatically upon compressor discharge pressure exceeding a preselected value.

Overspeed protection for a gas turbine/steam turbine combined cycle

A gas turbine is solidly coupled with rigid couplings in tandem with a reheat steam turbine and utilizes the combined inertia of the rotating members and the braking torque of the gas turbine air compressor to assist a single control system to limit overspeed of the complete unit. In its broadest and preferred form, the normal intercept steam valves and reheat stop valve between the reheater and the lower pressure steam turbine sections are eliminated, and the high pressure steam control valves are used to prevent overspeed, with steam flowing through a 'valveless' conduit from the reheater to the lower pressure steam turbine sections. The control system includes means for sensing a potential overspeed condition and operating the control valves to prevent overspeed. In a modified form of the invention of dump valve may be provided between the air compressor discharge and the combustion chamber of the gas turbine. In the modified form the control system will also open the dump valve, or the dump valve may open automatically upon compressor discharge pressure exceedng a preselected value.

A gas turbine is solidly coupled with rigid couplings in tandem with a reheat steam tubine and utilizes the combined inertia of the rotating members and the braking torque of the gas turbine air compressor to assist a single control system to limit overspeed of the complete unit. In its broadest and preferred form, the normal intercept steam valves and reheat stop valve between the reheater and the lower pressure steam turbine sections are eliminated, and the high pressure steam control valves are used to prevent overspeed, with steam flowing through a 'valveless' conduit from the reheater to the lower pressure steam turbine sections. The control system includes means for sensing a potential overspeed condition and operating the control valves to prevent overspeed. In a modified form of the invention a dump valve may be provided between the air compressor discharge and the combustion chamber of the gas turbine. In the modified form the control system will also open the dump valve, or the dump valve may open automatically upon compressor discharge pressure exceeding a preselected value.

A method for starting and loading a combined cycle turbine of the type having a gas turbine with a fuel flow control valve and a steam turbine with at least one steam control valve both disposed on a single shaft and having a heat recovery steam generator heated by said gas turbine and connected to supply steam to the steam control valve, the combined cycle turbine having a unified control system and driving a load and also having an auxiliary steam source connected to the steam control valve. The improved method comprises starting and cranking the combined unit by controlling steam from the auxiliary steam source with the steam control valve, initiating and controlling fuel flow to the gas turbine with the fuel flow control valve, initiating combustion, controlling acceleration of the combined unit with the steam control valve, transferring acceleration control of the combined unit to the gas turbine fuel flow control valve, and accelerating the combined unit to rated speed. The method further includes the steps of synchronizing the combined unit to the line, substituting steam from the heat recovery steam generator for that from the auxiliary steam source, and opening said steam control valves to a full open position.

Control system for single shaft combined cycle gas and steam turbine unit

Overspeed protection method for a gas turbine/steam turbine combined

An improved combined cycle plant with a gas turbine, a steam turbine and a generator arranged in tandem on a single shaft system in the order aforementioned, including a single thrust bearing with rigidly coupled rotor members. A thrust bearing for the shaft system is supported in a bearing standard keyed to the foundation on the side of the steam turbine toward the gas turbine to restrain axial movement. The thrust bearing is preferably located in the compressor inlet of the gas turbine. The steam turbine comprises a first casing with the hihg pressure section supported in a bearing standard keyed to the foundation adjacent the thrust bearing. The second casing with the low pressure section is keyed to the foundation at its outlet in the center of the exhaust hood. In a preferred arrangement with a single flow low pressure turbine section, the second casing combines an intermediate pressure turbine section adjacent the generator receiving steam from the reheater. In a modified arrangement with a double flow low pressure section, the intermediate pressure turbine section turbine section is combined with the high pressure turbine section in the first casing.

Single shaft combined cycle turbine

A turning gear apparatus mounted adjacent the bull gear of a large turbomachine rotor has a carriage pivotably mounted to the frame, a first pinion rotatably mounted on the carriage, and a second pinion continuously engaging the first pinion and rotatably mounted to the frame coaxial with the carriage pivoting axis. The improvement comprises locating the carriage on the side of the bull gear where it rotates in an upward direction, with the axis of the second pinion located such that when the carriage is pivoted and the first pinion engages the bull gear, the axis of rotation of the first pinion is located on a selected angle below the horizintal substantially equal to the pressure angle of the bull gear tooth, resulting in substantially vertical reaction forces. Also in the preferred embodiment, the pivotable carriage is rendered bi-stable by disposing the first pinion above the second pinion and providing stops such that the pivotable turning gear carriage has a center of gravity which falls on either side of a vertical line through the pivot point and above the pivot point, when the carriage is positioned on the respective stops in the engaged or disengaged position.

Turning gear engagement device

Discloses a backup lube oil pump system for a steam turbine lube oil system. The primary and secondary pump system of the prior art lube oil system normally includes a primary centrifugal pump affixed to the turbine shaft and ac and dc motor-driven pumps to supply lubrication during start-up and shutdown when the primary pump cannot maintain flow due to low rotational speed. If the turbine is coasting down due to an ac power failure, the ac motor-driven backup pump is inoperative. The dc (battery) driven backup pump becomes the only backup left and the failure of batteries if not charged regularly can render it as a poor backup system. In the invention a backup lube oil system having high reliability utilizes a positive displacement lube oil pump driven by a rotor-driven permanent magnet generator. The pump is in parallel with a primary check valve in the lube oil feed line, so that the positive displacement backup lube oil pump is supplying oil at all times to the shaft bearing. Upon coast-down of the rotor, the PDP driven by the permanent magnet generator maintains a continuous flow of oil to the shaft bearings to a speed which is sufficiently low to prevent bearing damage in case the primary and other backup systems fail to do so.

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Schenectady, NY, United States of America

James H Moore