System and Method for Full Combustion Optimization For Pulverized Coal-Fired Steam Boilers

Abstract

A method and system for controlling a pulverized coal fired boiler wherein the flow of a coal/air mixture flowing to each burner is monitored and transmitted to a distributed control system. The distributed control system also monitors and controls the position of dampers in a splitter that feeds the coal/air mixture to the burners. The dampers are controlled in a closed loop fashion to achieve a optimal boiler performance.

1 . A system for controlling a pulverized coal-fired boiler having at least one pulverizer for pulverizing coal and forming an air and coal mixture, a plurality of burners, each said burner fed said air and coal mixture by a burner line, said system comprising;
 a combustion optimization system having a combustion model of the pulverized coal-fired boiler;   a distributed control system in communication with said combustion optimization system and receiving control commands from said combustion optimization system;   a coal flow sensor positioned to monitor the velocity of said air and coal mixture fed into each said burner;   an air flow homogenizer positioned downstream of said pulverizer, said air flow homogenizer having a splitter for separating said air and coal mixture into said burner lines, said splitter having a plurality of dampers to control the flow of said air and coal mixture flowing to said burners; and   wherein said distributed control system controls the position of said dampers in a closed loop fashion using a signal indicative of the present position of said dampers in combination with signals from the coal flow sensors.   
     
     
         2 . The system according to  claim 1  further comprising one or more positioners that transmit a signal indicative of the position of each said damper to said distributed control system. 
     
     
         3 . The system according to  claim 2  wherein said one or more positioners move a associated one of said dampers to a setpoint transmitted from said distributed control system. 
     
     
         4 . The system according to  claim 1  wherein said combustion optimization system further including a cost function, said cost function including weighted customer optimization targets. 
     
     
         5 . The system according to  claim 4  wherein said combustion optimization system utilizes said combustion model and a cost function to provide setpoint and setpoint bias values to the distributed control system. 
     
     
         6 . The system according to  claim 1  further comprising flame detectors positioned proximate to said burners to detect the presence or absence of flame and also measure the quality of the flame to said distributed control system. 
     
     
         7 . The system according to  claim 1  wherein said coal flow sensor further monitors coal concentration and temperature of said air and coal mixture flowing into each burner.