초록 ▼

A steam and gas turbine combined cycle plant STAG* employs a catalyst in a heat recovery steam generator to react injected ammonia with NOx from the combustor of the gas turbine to reduce atmospheric emission of NOx from the system. Rapid control of ammonia injection is achieved using a prediction o

A steam and gas turbine combined cycle plant STAG* employs a catalyst in a heat recovery steam generator to react injected ammonia with NOx from the combustor of the gas turbine to reduce atmospheric emission of NOx from the system. Rapid control of ammonia injection is achieved using a prediction of the NOx being generated in dependence upon the operating conditions of the combustor. A trimming signal from a measurement of NOx being emitted from the heat recovery steam generator downstream of the catalyst is employed to complete the NOx control loop. Compensation is provided to relate the measured NOx downstream of the catalyst with the NOx in the output of the gas turbine taking into account the catalyst efficiency.

대표청구항 ▼

An ammonia control system for controlling a flow of ammonia into an exhaust of a fuel combustion apparatus to enable reaction of NOx in said exhaust with said ammonia in a catalyst for reduction of NOx effluent into the atmosphere, including a controller effective to produce a predicted NOx signal r

An ammonia control system for controlling a flow of ammonia into an exhaust of a fuel combustion apparatus to enable reaction of NOx in said exhaust with said ammonia in a catalyst for reduction of NOx effluent into the atmosphere, including a controller effective to produce a predicted NOx signal related to parameters in said combustion apparatus and at least one NOx setpoint signal representing a desired NOx condition downstream of said catalyst, a NOx analyzer producing a measured NOx signal related to a relative volume concentration of NOx downstream of said catalyst, comprising: means for converting said measured NOx signal in terms of relative volume concentration into a NOx flow rate in terms of moles of NOx per unit time; said at least one NOx setpoint signal being in terms of moles of NOx per unit time; means for differencing the converted measured NOx flow rate and the NOx setpoint signal to produce a NOx error signal; means for producing a mole ratio signal of ammonia to NOx in response to said NOx error signal; means for multiplying said mole ratio signal by said predicted NOx signal to produce an ammonia command signal; and an ammonia supply responsive to said ammonia command signal for injecting ammonia into said exhaust. A method for controlling a flow of ammonia into an exhaust of a fuel combustion apparatus to enable reaction of NOx in said exhaust with said ammonia in a catalyst for reduction of NOx effluent into the atmosphere, said apparatus being effective to produce a predicted NOx signal related to parameters in said combustion apparatus and at least one NOx setpoint signal representing a desired NOx condition downstream of said catalyst, a NOx analyzer producing a measured NOx signal related to a relative volume concentration of NOx downstream of said catalyst, comprising the steps of: converting said measured NOx signal in terms of relative volume concentration into a NOx flow rate in terms of moles of NOx per unit time; differencing the converted measured NOx flow rate and the NOx setpoint signal to produce a NOx error signal; producing a mole ratio signal of ammonia to NOx in response to said NOx error signal; multiplying said mole ratio signal by said predicted NOx signal to produce an ammonia command signal; and injecting said ammonia into said exhaust in response to said ammonia command signal.