Westinghouse Electric Corporation

Richard J Plotnick

Lyle F Martz

A combined cycle electric power plant includes gas and steam turbines and a steam generator for recovering the heat in the exhaust gases exited from the gas turbine and for using the recovered heat to produce and supply steam to the steam turbine. The steam generator includes a superheater tube through which a fluid, e.g. water, is directed to be additionally heated into superheated steam by the exhaust gas turbine gases. An afterburner further heats the exhaust gas turbine gases passed to the superheater tube. The temperature of the gas turbine exhaust gases is sensed for varying the fuel flow to the afterburner by a fuel valve, whereby the temperatures of the gas turbine exhaust gases and therefore of the superheated steam, are controlled. Further, override signals are generated to prevent the temperature of the superheated steam from falling below a predetermined minimum level and for preventing the temperature and pressure of the superheated steam from exceeding maximum levels.

Combined cycle electric power plant and a heat recovery steam generator

A combined cycle electric power plant includes gas and steam turbines and a steam generator for recovering the heat in the exhaust gases exited from the gas turbine and for using the recovered heat to produce and supply steam to the steam turbine. The steam generator includes a superheater tube and a steam drum from which heated steam is directed through the superheater to be additionally heated into superheated steam by the exhaust gas turbine gases. An afterburner serves to further heat the exhaust gas turbine gases passed to the superheater tube and a bypass conduit is disposed about the superheater tube whereby a variable steam flow determined by a bypass valve disposed in the bypass conduit may be directed about the superheater tube to be mixed with the superheated steam therefrom, whereby the temperature of the superheated steam supplied to the steam turbine may be accurately controlled. Steam temperature control means includes a first control loop responsive to the superheated steam temperature for regulating the position of the bypass valve with respect to a first setpoint, and a second control loop responsive to the superheated steam temperature for controlling the fuel supply to the afterburner with respect to a second setpoint varying in accordance with the bypass valve position. In particular, as the bypass valve position increases, the second setpoint, originally higher than, is lowered toward a value substantially equal to that of the first setpoint.

Combined cycle electric power plant and heat recovery steam generator

A combined cycle electric power plant includes gas and steam turbines and a steam generator for recovering the heat in the exhaust gases exited from the gas turbine and for using the recovered heat to produce and supply steam to the steam turbine. The steam generator includes an economizer tube and a high pressure evaporator tube and a boiler feed pump for directing the heat exchange fluid serially through the aforementioned tubes. A condenser is associated with the steam turbine for converting the spent steam into condensate water to be supplied to a deaerator for removing undesired air and for preliminarily heating the water condensate before being pumped to the economizer tube. Condensate flow through the economizer tube is maintained substantially constant by maintaining the boiler feed pump at a predetermined, substantially constant rate. A bypass conduit is provided to feed back a portion of the flow heated in the economizer tube to the deaerator; the portion being equal to the difference between the constant flow through the economizer tube and the flow to be directed through the high pressure evaporator tube as required by the steam turbine for its present load.

A combined cycle electric power plant includes gas and steam turbines and a steam generator for recovering the heat in the exhaust gases exited from the gas turbine and for using the recovered heat to produce and supply steam to the steam turbine. A condenser receives the spent steam from the steam turbine for converting it into condensate. The steam generator includes a deaerator for receiving the condensate flow from the condenser and for storing it in a storage portion, a feedwater pump for directing the stored condensate through a first heat exchange tube whereby heat is transferred from the gas turbine exhaust gases to the fluid, a main drum for receiving and storing the heated fluid and a second heat exchange tube for heating the fluid by the gas turbine exhaust gases into superheated steam to be supplied to the steam turbine. A water make-up system is associated with the condenser and includes a water make-up storage tank, a return valve for extracting condensate from that supplied to the deaerator for storage in the water make-up storage tank, and a make-up valve for returning water from the water make-up storage tank into the condenser. Fluid level control is provided for maintaining the fluid level within a hotwell storage portion of the condenser, and within the storage portion of the deaerator, by controlling the position of the condensate valve. In particular, the fluid level control is responsive primarily to a measurement of the superheated steam as supplied to said steam turbine and in particular to a difference signal between the flow of superheated steam to said steam turbine and the condensate flow to said deaerator for the control of the position of the condensate valve, and secondarily, to measurements of the fluid level within the deaerator storage portion and the hotwell storage portion to trim the effect of the aforementioned difference signal upon the position of the condensate valve.

A combined cycle electric power plant includes gas and steam turbines and a steam generator for recovering the heat in the exhaust gases exited from the gas turbine and for using the recovered heat to produce and supply steam to the steam turbine. A condenser is associated with the steam turbine for converting the spent steam from the steam turbine into condensate to be supplied to the steam generator. The steam generator includes a low pressure storage tank, a first heat exchange tube, a boiler feedwater pump for directing fluid from the low pressure storage tank through the first heat exchange tube, a main storage drum, a second heat exchange tube, and a high pressure recirculation pump for directing water from the main storage drum through the second heat exchange tube. An afterburner further heats the exhaust gas turbine gases passed to the first and second heat exchange tubes. Method and apparatus are provided for controlling the transfer of the operation of the steam generator from a WET mode of operation to a DRY mode of operation. In particular, the heat supplied to the gas turbine exhaust gases is reduced, the fluid introduced into the steam generator is cut off, a blowdown valve for directing fluid from the steam generator is opened to further drain fluid therefrom, heat is continued to be supplied to the first and second heat exchange tubes whereby steam is continued to be generated within said generator and directed to the steam turbine, and finally the outlets associated with the steam generator are closed and the steam generator is filled with a suitable non-corrosive fluid such as nitrogen gas.

Growing community of inventors

Cherry Hill, NJ, United States of America

Richard J Plotnick