Combined cycle electric power plant and a heat recovery steam generator having improved boiler feed pump flow control
First Claim
1. A combined cycle electric power plant comprising:
- a. at least one gas turbine including an exit through which heated exhaust gases pass;
b. means for generating steam at varying rates dependent upon the load placed upon said steam turbine, coupled to said gas turbine exit by transferring heat from the exhaust gases to a fluid passing through said steam generating means;
c. a steam turbine coupled to said steam generating means and driven by the steam supplied thereby;
d. means for generating electric power by the driving power of said turbines;
e. condenser means for receiving and converting the spent steam from said steam turbine into condensate;
f. means for controlling the operation of said turbines and said steam generating means;
g. said steam generating means including first and second heat exchange tubes, each having an inlet and outlet, said outlet of said first heat exchange tube being coupled to said inlet of said second heat exchange tube, pump means for directing the condensate from said condenser serially through said first and second heat exchange tubes, the steam derived from said second heat exchange tubes being supplied to drive said steam turbine, a recirculation conduit coupled between the outlet of said first heat exchange tube and its inlet, and a recirculation control valve inserted within said recirculation conduit and selectively controlled to permit a variable recirculation flow to said inlet of said first heat exchange tube; and
h. said controlling means comprising pump control means for actuating said pump to establish fluid flow through said first heat exchange tube at a substantially constant rate set for all loads imposed upon said steam turbine to achieve an optimum heat transfer between the exhaust gases and the fluid directed through said steam generating means to provide sufficient steam to said steam turbine at maximum load, and valve control means for controlling said valve to permit a variable, first flow through said recirculation conduit proportional to the difference between the constant flow established by said pump through said first heat exchange tube and a second flow to said second heat exchange tube, the second flow being set in accordance with the load imposed upon said steam turbine.
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Accused Products
Abstract
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.
65 Citations
27 Claims
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1. A combined cycle electric power plant comprising:
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a. at least one gas turbine including an exit through which heated exhaust gases pass; b. means for generating steam at varying rates dependent upon the load placed upon said steam turbine, coupled to said gas turbine exit by transferring heat from the exhaust gases to a fluid passing through said steam generating means; c. a steam turbine coupled to said steam generating means and driven by the steam supplied thereby; d. means for generating electric power by the driving power of said turbines; e. condenser means for receiving and converting the spent steam from said steam turbine into condensate; f. means for controlling the operation of said turbines and said steam generating means; g. said steam generating means including first and second heat exchange tubes, each having an inlet and outlet, said outlet of said first heat exchange tube being coupled to said inlet of said second heat exchange tube, pump means for directing the condensate from said condenser serially through said first and second heat exchange tubes, the steam derived from said second heat exchange tubes being supplied to drive said steam turbine, a recirculation conduit coupled between the outlet of said first heat exchange tube and its inlet, and a recirculation control valve inserted within said recirculation conduit and selectively controlled to permit a variable recirculation flow to said inlet of said first heat exchange tube; and h. said controlling means comprising pump control means for actuating said pump to establish fluid flow through said first heat exchange tube at a substantially constant rate set for all loads imposed upon said steam turbine to achieve an optimum heat transfer between the exhaust gases and the fluid directed through said steam generating means to provide sufficient steam to said steam turbine at maximum load, and valve control means for controlling said valve to permit a variable, first flow through said recirculation conduit proportional to the difference between the constant flow established by said pump through said first heat exchange tube and a second flow to said second heat exchange tube, the second flow being set in accordance with the load imposed upon said steam turbine. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A control system for a heat recovery steam generator for circulating varying rates of steam flow to and from a steam turbine dependent upon the varying loads placed upon the steam turbine associated with a condenser for converting the spent steam from said steam turbine to condensate, said steam generator including first and second heat exchange tubes for extracting heat from heated gases directed therepast, each having an inlet and outlet, said outlet of said first heat exchange tube being coupled to said inlet of said second heat exchange tube, the steam derived from said second heat exchange tube being supplied to drive the steam turbine, pump means for directing the condensate from said condenser serially to said first and second heat exchange tubes, a recirculation conduit coupled from the outlet of said first heat exchange tube and its inlet, and a recirculation control valve inserted within said recirculation conduit and selectively controlled to permit a variable recirculation flow to said inlet of said first heat exchange tube, said control system comprising:
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a. pump control means for actuating and controlling said pump means to establish a fluid flow through said first heat exchange tube at a substantially constant rate set for all loads imposed upon the steam turbine to achieve an optimum heat transfer between the heated gases and the condensate directed therethrough and to provide sufficient steam to the steam turbine at maximum load; and b. valve control means for controlling said valve to permit a first variable flow through said recirculation conduit proportional to the difference between the constant flow established by said pump through said first heat exchange tube and a second required flow to said second heat exchange tube, the second flow being set in accordance with the load imposed upon the steam turbine. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A steam turbine power plant comprising:
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a. steam generator means responsive to heated gases directed therethrough for converting a fluid into steam and supplying the steam to a steam turbine at a varying rate dependent upon the load imposed upon said steam turbine; b. said steam turbine coupled to said steam generating means and driven by the steam supplied thereby; c. means for generating electric power by the driving power of said steam turbine; d. a condenser for receiving and converting the spent steam from said steam turbine into condensate; e. means for controlling the operation of said steam turbine and said steam generating means; f. said steam generating means including first and second heat exchange tubes, the steam derived from said second heat exchange tube being supplied to said steam turbine, each having an inlet and outlet, said outlet of said first heat exchange tube being coupled to said inlet of said second heat exchange tube, pump means for directing the condensate from said condenser serially through said first and second heat exchange tubes, a recirculation conduit coupled between the outlet of said first heat exchange tube and its inlet, and a recirculation control valve inserted within said recirculation conduit and selectively controlled to permit a first, variable recirculation flow to said inlet of said first heat exchange tube; and g. said controlling means comprising pump control means for actuating said pump to establish fluid flow through said first heat exchange tube at a substantially constant rate for all loads imposed upon said steam turbine to achieve an optimum heat transfer between the heated gases and the condensate directed through said first heat exchange tube and to provide sufficient steam to said steam turbine at its maximum load, and valve control means for controlling said valve to permit the first, variable flow through said recirculation conduit proportional to the difference between the constant flow established by said pump through said first heat exchange tube and a second flow to said second heat exchange tube, the second flow being set in accordance with the load imposed upon said steam turbine. - View Dependent Claims (22, 23, 24, 25)
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26. A combined cycle electric power plant comprising:
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a. at least one gas turbine including an exit through which heated exhaust gases pass; b. means for generating steam at varying rates dependent upon the load placed upon said steam turbine, coupled to said gas turbine exit by transferring heat from the exhaust gases to a fluid passing through said steam generating means; c. a steam turbine coupled to said steam generating means and driven by the steam supplied thereby; d. means for generating electric power by the driving power of said turbines; e. condenser means for receiving and converting the spent steam from said steam turbine into condensate; f. means for controlling the operation of said turbines and said steam generating means; g. said steam generating means including first and second heat exchange tubes, each having an inlet and outlet, said outlet of said first heat exchange tube being coupled to said inlet of said second heat exchange tube, pump means for directing the condensate from said condenser serially through said first and second heat exchange tubes, the steam derived from said second heat exchange tube being supplied to drive said steam turbine, a recirculation conduit coupled between the outlet of said first heat exchange tube and its inlet, and a recirculation control valve inserted within said recirculation conduit and selectively controlled to permit a variable recirculation flow to said inlet of said first heat exchange tube; h. said controlling means comprising pump control means for actuating said pump to establish a fluid flow at a substantially constant rate set for all loads imposed upon said steam turbine to achieve an optimum heat transfer between the exhaust gases and the fluid directed through said steam generating means and to provide sufficient steam to said steam turbine at maximum load, and valve control means for controlling said valve to permit a variable, first flow through said recirculation conduit proportional to the difference between the constant flow established by said pump through said first heat exchange tube and a second flow to said second heat exchange tube, the second flow being set in accordance with the load imposed upon said steam turbine; and i. condensate storage means coupled to said recirculation conduit to receive the recirculated flow and to receive the condensate from said condenser means, for preheating the condensate with heat stored in the recirculated flow before directing the preheated condensate to said inlet of said first heat exchange tube.
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27. A steam turbine power plant comprising:
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a. steam generator means responsive to heated gases directed therethrough for converting a fluid into steam and supplying the steam to a steam turbine at a varying rate dependent upon the load imposed upon said steam turbine; b. said steam turbine coupled to said steam generating means and driven by the steam supplied thereby; c. means for generating electric power by the driving power of said steam turbine; d. a condenser for receiving and converting the spent steam from said steam turbine into condensate; e. means for controlling the operation of said steam turbine and said steam generating means; f. said steam generating means including first and second heat exchange tubes, the steam derived from said second heat exchange tube being supplied to said steam turbine, each having an inlet and outlet, said outlet of said first heat exchange tube being coupled to said inlet of said second heat exchange tube, pump means for directing the condensate from said condenser serially through said first and second heat exchange tubes, a recirculation conduit coupled between the outlet of said first heat exchange tube and its inlet, and a recirculation control valve inserted within said recirculation conduit and selectively controlled to permit a first, variable recirculation flow to said inlet of said first heat exchange tube; g. said controlling means comprising pump control means for actuating said pump to establish fluid flow through said first heat exchange tube at a substantially constant rate for all loads imposed upon said steam turbine to achieve an optimum heat transfer between the heated gases and the condensate directed through said first heat exchange tube and to provide sufficient steam to said steam turbine at its maximum load, and valve control means for controlling said valve to permit the first, variable flow through said recirculation conduit proportional to the difference between the constant flow established by said pump through said first heat exchange tube and a second flow to said second heat exchange tube, the second flow being set in accordance with the load imposed upon said steam turbine; and h. storage means coupled to said recirculation conduit to receive the recirculated flow and to receive the condensate from said condenser for preheating the condensate by the heat stored in the recirculated flow before directing the preheated condensate to said first heat exchange tube.
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Specification