| 摘要 |
A plant with a gas turbine such as a combined cycle power plant of a gas turbine cycle and a steam turbine cycle is provided with a nitrogen oxide removal device for removing NOx by injecting ammonia to an exhaust gas of the gas turbine. The device reduces NOx concentration to a certain value or less before the exhaust gas is released to the air. An ammonia flow amount is rapidly controlled such that a mole ratio of ammonia to NOx coincides with a set mole ratio value. The mole ratio is calculated from a predicted NOx concentration at an inlet of the nitrogen oxide removal device predicted by calculating operation conditions of the gas turbine, an ammonia flow amount value, and an exhaust gas flow amount. The set mole ratio value is calculated from a deviation of a measured NOx concentration value at an outlet of the nitrogen oxide removal device and a set NOx concentration value, and an amount of water injected to a combustor. Finally, a controlled system is stabilized in a state where a measured NOx concentration value coincides with the set NOx concentration value at a high speed.
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