Metering combustion control

Abstract

Metering combustion control in a fired equipment is disclosed in which both the fuel flow rate and the combustion air flow rate are metered in a desired ratio corresponding to a master firing rate demand, and the master firing rate demand combustion air flow directed to the combustion air regulating element is trimmed in response to an error based correction adjustment determined from the respective values of the fuel flow meter and combustion air flow meter input signals to drive the ratio between the fuel flow rate and the combustion air flow rate toward the desired ratio for controlling the combustion in accordance with the master firing rate demand.

1 . Method, comprising:
 controlling combustion in a fired equipment according to a master firing rate demand;   metering the fuel flow rate and the combustion air flow rate in a desired ratio to correspond to the master firing rate demand;   providing an error based correction adjustment based on the value of the fuel flow meter input signal and the value of the combustion air flow meter input signal, and   trimming the master firing rate demand signal value directed to the combustion air flow regulating element in response to the error based correction adjustment to drive the ratio between the fuel flow rate and the combustion air flow rate toward the desired ratio for controlling the combustion in accordance with the master firing rate demand.   
   
   
       2 . The method according to  claim 1  further comprising the fuel flow input signal and the combustion air flow input signal being input to a proportional integral derivative controller for determining the value of the error based correction adjustment. 
   
   
       3 . The method according to  claim 1  further comprising limiting in response to the failure of a fuel flow meter and/or an air combustion flow meter, the value of the error correction based adjustment to a predetermined allowable level to insure continued combustion. 
   
   
       4 . The method according to  claim 1  further comprising providing a turndown capability without dependence on flow meter flow signals. 
   
   
       5 . The method according to  claim 4  wherein the turndown capability is equivalent to a parallel positioning combustion control operation. 
   
   
       6 . The method according to  claim 1  further comprising providing a reduced response time capability without dependence on low selectors, high selectors or differences in independent fuel and air flow PID tunings. 
   
   
       7 . The method according to  claim 1  further comprising controlling the fuel British Thermal Unit (BTU) flow rate and controlling the combustion air oxygen mass flow rate. 
   
   
       8 . The method according to  claim 1  further comprising analyzing the oxygen level in the flue gas for adjusting the combustion air flow meter input signal. 
   
   
       9 . The method according to  claim 1  further comprising characterizing the opening of the fuel flow regulating element to produce a near linear fuel flow as a function of the trimmed master firing rate demand signal directed to the fuel flow regulating element. 
   
   
       10 . The method according to  claim 1  further comprising characterizing the opening/speed of the air flow regulating element to produce the desired fuel flow rate/combustion air flow rate ratio as a function of the trimmed master firing rate demand signal directed to the combustion air flow regulating element. 
   
   
       11 . A controller, comprising:
 one or more modules configured for controlling combustion in a fired equipment according to a master firing rate demand;   one or more modules configured for metering the fuel flow rate and the combustion air flow rate in a desired ratio to correspond to the master firing rate demand;   one or more modules configured for providing an error based correction adjustment based on the value of the fuel flow meter input signal and the value of the combustion air flow meter input signal, and   one or more modules configured for trimming the master firing rate demand signal value directed to the combustion air flow regulating element in response to the error based correction adjustment to drive the ratio between the fuel flow rate and the combustion air flow rate toward the desired ratio for controlling the combustion in accordance with the master firing rate demand.   
   
   
       12 . The controller according to  claim 11  further comprising one or more modules configured as a proportional integral derivative controller for determining the value of the error based correction adjustment based on the respective values of the fuel flow input signal and the combustion air flow input signal. 
   
   
       13 . The controller according to  claim 11  wherein said fired equipment is a boiler configured and arranged for generating steam. 
   
   
       14 . The controller according to  claim 11  wherein said fired equipment is a hot water heater. 
   
   
       15 . The controller according to  claim 11  wherein said fired equipment is at least one of a steam generator, a boiler, a chemical process heater, a heated manufacturing process, a boiler combustion fired equipment. 
   
   
       16 . A computer program product comprising a computer readable structure embodying computer program code therein for execution by a computer processor, said computer program further comprising instructions for performing a method comprising controlling combustion in a fired equipment according to a master firing rate demand; metering the fuel flow rate and the combustion air flow rate in a desired ratio to correspond to the master firing rate demand; providing an error based correction adjustment based on the value of the fuel flow meter input signal and the value of the combustion air flow meter input signal, and trimming the master firing rate demand signal value directed to the combustion air flow regulating element in response to the error based correction adjustment to drive the ratio between the fuel flow rate and the combustion air flow rate toward the desired ratio for controlling the combustion in accordance with the master firing rate demand. 
   
   
       17 . A method according to  claim 1  wherein the method further comprises implementing the steps of the method via a computer program running in a processor, controller or other suitable module located in or interfaced with the fired equipment. 
   
   
       18 . A chipset, comprising:
 a first chipset module configured for controlling combustion in a fired equipment by metering both the fuel flow rate and the combustion air flow rate in a desired ratio corresponding to a master firing rate demand, and   a second chipset module configured for trimming the master firing rate demand directed to the combustion air regulating element in response to an error based correction adjustment determined from the respective values of the fuel flow meter and combustion air flow meter input signals to drive the ratio between the fuel flow rate and the combustion air flow rate toward the desired ratio for controlling the combustion in accordance with the master firing rate demand.   
   
   
       19 . The chipset according to  claim 18  further comprising a proportional integral derivative controller configured for determining the value of the error based correction adjustment based on the respective values of the fuel flow input signal and the combustion air flow input signal.