Boiler and combustion control method

Abstract

Provided is a boiler ( 100 ) including: a burner ( 5 ); a fuel supply unit ( 10 ) for supplying fuel to the burner ( 5 ); a blowing unit ( 20 ) for supplying air to the burner ( 5 ); and a control unit ( 30 ) for adjusting an amount of fuel to be supplied to the burner ( 5 ) and a quantity of air to be supplied to the burner ( 5 ), in which the control unit ( 30 ) has a reference amount computing portion for calculating a reference fuel amount and a reference air quantity to be supplied to the burner ( 5 ) with respect to a required load, an air quantity computing portion that corrects the reference air quantity based on a temperature of the air to be supplied to the burner ( 5 ) and a temperature of the fuel to be supplied to the burner ( 5 ) and calculates the corrected air quantity as a supply air quantity, and a control portion that controls combustion at the burner based on the reference fuel amount and the supply air quantity.

1 . A boiler comprising: a control means for adjusting a quantity of air to be used for combustion based on a temperature change in an air and fuel to be used for combustion. 
   
   
       2 . A boiler according to  claim 1  further comprising:
 a burner;   a fuel supply means for supplying fuel to the burner;   a blowing means for supplying air to the burner; and   an amount of fuel to be supplied to the burner and a quantity of air to be supplied to the burner, which are adjusted by the control means,   wherein the control means has a reference amount computing portion for calculating a reference fuel amount and a reference air quantity to be supplied to the burner with respect to a required load, an air quantity computing portion that corrects the reference air quantity based on a temperature of the air to be supplied to the burner and a temperature of the fuel to be supplied to the burner and calculates the corrected air quantity as a supply air quantity, and a control portion that controls combustion at the burner based on the reference fuel amount and the supply air quantity.   
   
   
       3 . A boiler according to  claim 2 , further comprising thermistors used as a means for measuring the temperature of the air to be supplied to the burner and as a means for measuring the temperature of the fuel to be supplied to the burner. 
   
   
       4 . A boiler according to  claim 3 , wherein the air quantity computing portion calculates the supply air quantity such that a correction amount for correcting the reference air quantity is in proportion to 1/(1+R TH1 /R s +R TH1 /R TH2 ), where R TH1  is a resistance value of an air temperature measuring thermistor, R TH2  is a resistance value of a fuel temperature measuring thermistor, and R s  is a resistance value of a fixed resistor. 
   
   
       5 . A boiler according to  claim 2 , wherein the air quantity computing portion calculates the supply air quantity such that a correction amount for correcting the reference air quantity is in proportion to T a /(T g ) 1/2 , where T g  is the temperature of the fuel measured by a fuel temperature measuring means, and T a  is the temperature of the air measured by an air temperature measuring means. 
   
   
       6 . A combustion control method by which combustion is performed at a predetermined air ratio, and in which NOx in an exhaust gas is suppressed to a level within a predetermined range, the combustion control method comprising:
 calculating a reference fuel amount and a reference air quantity corresponding to a required load of the boiler;   correcting the calculated reference air quantity based on temperatures of a fuel and an air to be used for combustion; and   performing combustion with the corrected air quantity and the reference fuel amount.