Automatic NOx control for a gas turbine
AssigneeWestinghouse Electric Corp.
InventorsWilliam L. McCarty, Achim A. Von Seelen
Life of this patent
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Abstract
A gas turbine power plant has coolant injected into the combustors in order to reduce the level of nitrogen oxide produced by the combustion of natural gas fuel and/or oil. A control system controls injection of coolant into the combustors in order to reduce NOx emissions, while improving turbine cycle efficiency and avoiding the possibility of over-injection of coolant to the point of flame-out in the combustor. PID controllers are used to provide percentage error bias in the control system, whereby adjustment of coolant injection follows turbine load in a manner that increases turbine efficiency.
Claims14
A gas turbine power plant having at least one gas turbine, said at least one gas turbine having at least one combustor, said power plant further having a system for controlling the flow of coolant injected into said at least one combustor and for measuring the amount of coolant flow, comprising:
- sensing means for measuring the amount of NOx emissions produced by said at least one gas turbine;
- first controller means for generating a first signal indicative of the percent error between an NOx emissions set point and said measured amount of NOx emissions;
- second controller means for generating a second signal indicative of the percent error between an adjusted coolant flow set point and said measured amount of coolant flow, said second controller means being responsive to said first signal to adjust said coolant flow set point;
- and
- injecting means for injecting said flow of coolant into said combustor, said injecting means responsive to said second signal.
In a gas turbine power plant having at least one gas turbine, each said gas turbine having at least one combustor, a method for controlling the flow of coolant injected into each said combustor, comprising the steps of:
- generating a first signal indicative of the percent error between an NOx emissions set point and the measured amount of NOx emissions produced by said power plant;
- adjusting a predetermined coolant flow set point in accordance with said first signal and producing therefrom a parameter indicative thereof;
- measuring the amount of coolant flow;
- generating a second signal indicative of the percent error between said parameter and the measured amount of coolant flow;
- and
- controlling said flow of coolant in accordance with said second signal.
Dependencies are inferred from the claim text.