Feedback control procedure in a characteristic system as vy control procedure NH3 injection rate to an apparatus for NOx removal using the same.

摘要

A method of controlling the injection rate of NH 3 for use in an apparatus for removing NOX in which a molar ratio (K '240) a rate (210) injection of NH3 into said apparatus NOX removal with respect to a flow (204) of NOX at an inlet of said apparatus NOX removal and concentration (PV, 221) of NOX in an output of said apparatus NOX removal shows a characteristic curve form of V protruding downward on a plane where said molar ratio (K '240) and said concentration (PV 221) of NO X are expressed as coordinates X - Y, said process control injection rate NH3 to suppress the concentration (PV, 221) of NOX to below a desired predetermined concentration (SV, 222) of NOX reaches a minimum through the use of said rate (210) injection of NH3, characterized It comprising: a step of, when an operating area December ho removing apparatus NOX is divided into a first zone (I) in which said molar ratio (K ', 240) is less than a molar ratio (K0) at a minimum point where said concentration (PV, 221 ) NOX assumes a minimum value and a second zone (II) in which said molar ratio (K ', 240) is equal to or greater than said molar ratio (K 0) of said minimum point, set a concentration (223) virtual nO X with respect to said molar ratio (K ', 240) in accordance with a virtual characteristic line which varies monotonically to stride across a desired operating point without rising with an increase of said molar ratio (K' ' , 240) from said first zone (I) towards said second area (II), and a step of implementing feedback control for adjusting said rate (210) injection of NH3 with respect to said flow (204) of NOX on basis of a difference between said desired concentration (SV, 222) and said virtual NOX concentration (231) of NOX in a direction in which said virtual concentration (231) of NO X is brought close to said desired concentration (SV, 222) of NO X.