Feedback control method in V-shaped characteristic system, and NH3 injection rate control method for NOx removal apparatus using the same
First Claim
1. An NH3 injection rate control method for use in an NOx removal apparatus in which a correlation between a molar ratio of an NH3 injection rate into said NOx removal apparatus with respect to an NOx flow rate at an inlet of said NOx removal apparatus and an NOx concentration at an outlet of said NOx removal apparatus shows a downwardly protrusive V-shaped characteristic curve on a plane where said molar ratio and said NOx concentration are expressed in the form of X-Y coordinates, said NH3 injection rate control method for suppressing said NOx concentration to below a predetermined desired NOx concentration through the use of said NH3 injection rate reaching a minimum comprising:
- a step of, when an operating area of said NOx removal apparatus is divided into a first area in which said molar ratio is smaller than a molar ratio at a minimum point where said NOx concentration assumes a minimum value and a second area in which said molar ratio is equal to or larger than said minimum point molar ratio, setting a virtual NOx concentration with respect to said molar ratio according to a virtual characteristic line which varies monotonically to stride across a desired operating point without rising with an increase of said molar ratio from said first area to said second area; and
a step of implementing feedback control for adjusting said NH3 injection rate with respect to said NOx flow rate on the basis of a deviation between said desired NOx concentration and said virtual NOx concentration in a direction that said virtual NOx concentration is brought close to said desired NOx concentration.
1 Assignment
0 Petitions
Accused Products
Abstract
In the NH3 injection rate control method for an NOx removal apparatus, operating area of the apparatus is divided into first area in which molar ratio of NH3 injection rate with respect to NOx flow rate at an inlet of the apparatus is smaller than molar ratio at minimum point where NOx concentration assumes minimum value and second area in which the molar ratio is equal to or larger than the minimum point molar ratio, and virtual NOx concentration with respect to the molar ratio is set according to virtual characteristic line which varies monotonically to stride across desired operating point without rising with increase of the molar ratio from the first area to the second area. Moreover, feedback control is implemented for adjusting the NH3 injection rate with respect to the NOx flow rate in direction that the virtual NOx concentration is brought close to the desired NOx concentration.
16 Citations
13 Claims
-
1. An NH3 injection rate control method for use in an NOx removal apparatus in which a correlation between a molar ratio of an NH3 injection rate into said NOx removal apparatus with respect to an NOx flow rate at an inlet of said NOx removal apparatus and an NOx concentration at an outlet of said NOx removal apparatus shows a downwardly protrusive V-shaped characteristic curve on a plane where said molar ratio and said NOx concentration are expressed in the form of X-Y coordinates, said NH3 injection rate control method for suppressing said NOx concentration to below a predetermined desired NOx concentration through the use of said NH3 injection rate reaching a minimum comprising:
-
a step of, when an operating area of said NOx removal apparatus is divided into a first area in which said molar ratio is smaller than a molar ratio at a minimum point where said NOx concentration assumes a minimum value and a second area in which said molar ratio is equal to or larger than said minimum point molar ratio, setting a virtual NOx concentration with respect to said molar ratio according to a virtual characteristic line which varies monotonically to stride across a desired operating point without rising with an increase of said molar ratio from said first area to said second area; and
a step of implementing feedback control for adjusting said NH3 injection rate with respect to said NOx flow rate on the basis of a deviation between said desired NOx concentration and said virtual NOx concentration in a direction that said virtual NOx concentration is brought close to said desired NOx concentration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. An NH3 injection rate control unit for use in an NOx removal apparatus in which a correlation between a molar ratio of an NH3 injection rate into said NOx removal apparatus with respect to an NOx flow rate at an inlet of said NOx removal apparatus and an NOx concentration at an outlet of said NOx removal apparatus shows a downwardly protrusive V-shaped characteristic curve on a plane where said molar ratio and said NOx concentration are expressed in the form of X-Y coordinates, said control unit comprising:
-
NOx concentration detecting means for detecting said NOx concentration at said outlet of said NOx removal apparatus;
desired NOx concentration setting means for setting a desired NOx concentration at said outlet of said NOx removal apparatus;
NOx flow rate detecting means for detecting said NOx flow rate at said inlet of said NOx removal apparatus;
NH3 injection rate adjusting means for adjusting said NH3 injection rate into said NOx removal apparatus;
virtual NOx concentration setting means for, when an operating area of said NOx removal apparatus is divided into a first area in which said molar ratio is smaller than a molar ratio at a minimum point where said NOx concentration assumes a minimum value and a second area in which said molar ratio is equal to or larger than said minimum point molar ratio, setting a virtual NOx concentration with respect to said molar ratio according to a virtual characteristic line which varies monotonically to stride across a desired operating point without rising with an increase of said molar ratio from said first area to said second area; and
feedback control means for adjusting, through the use of said NH3 injection rate adjusting means, said NH3 injection rate on the basis of said NOx flow rate, detected by said NOx flow rate detecting means, in accordance with a deviation between said desired NOx concentration and said virtual NOx concentration, set by the virtual NOx concentration setting means, in a direction that said virtual NOx concentration is brought close to said desired NOx concentration.
-
-
12. A feedback control method for use in a V-shaped characteristic system in which a correlation between input and output values shows a V-shaped characteristic curve having one minimum point on a plane where said input and output values are expressed in the form of X-Y coordinates, said feedback control method for bringing said output value close to a desired output value, said control method comprising:
-
a step of, when an operating area of said system is divided into a first area in which a deviation between said input value and an input value at said minimum point has a specific sign and a second area having a sign different from said specific sign, setting a virtual output value with respect to said input value according to a virtual characteristic line which varies monotonically to stride across a desired operating point so that an inclination of said output value to said input value in said first area and an inclination of said output value to said input value in said second area do not have different signs; and
a step of changing said input value on the basis of a deviation between said desired output value and said virtual output value in a direction that said virtual output value is brought close to said desired output value.
-
-
13. A control unit for use in a V-shaped characteristic system in which a correlation between input and output values shows a V-shaped characteristic curve having one minimum point on a plane where said input and output values are expressed in the form of X-Y coordinates, said control unit comprising:
-
detecting means for detecting said output value from said system;
desired out put value setting means for setting a desired output value;
inputting means for inputting said input value to said system;
virtual output value setting means for, when an operating area of said system is divided into a first area in which a deviation between said input value and an input value at said minimum point has a specific sign and a second area having a sign different from said specific sign, setting a virtual output value with respect to said input value according to a virtual characteristic line which varies monotonically to stride across a desired operating point so that an inclination of said output value to said input value in said first area and an inclination of said output value to said input value in said second area do not have different signs; and
feedback control means for changing said input value on the basis of a deviation between said desired output value and said virtual output value in a direction that said virtual output value is brought close to said desired output value.
-
Specification