Apparatus and method for a modulating burner controller

Abstract

This invention describes a modulating burner controller device for varying burner combustion over a wide range and has an output that integrates the control of all functions required to operate the burner. Specifically, the controller uses measured feedback from a fuel flow sensor to attain the proper mixture of fuel and air for optimum combustion performance for both individual and multiple the burner applications.

1 . A combustion apparatus for use in fired variable demand applications, the apparatus comprising:
 a fuel valve modulating a fuel flow;   a fuel sensor with a range measuring the fuel flow and sending a fuel output;   a combustion air device modulating an air flow;   an air sensor measuring the air flow and sending an air output; and   a controller connected to the fuel valve, the fuel sensor, the combustion air device, and the air sensor, the controller modulating the fuel valve based on the fuel output using an extrapolation algorithm when the fuel output extends outside of the range of the fuel sensor, the controller modulating the combustion air device based on the air output;   wherein the controller simultaneously or sequentially modulates the fuel flow and the air flow over an extended fuel/air ratio and provides continuous modulation during a single burn cycle.   
   
   
       2 . The apparatus according to  claim 1 , wherein the extrapolation algorithm comprises fuzzy logic derived from a fuel sensor curve over the range. 
   
   
       3 . The apparatus according to  claim 1 , wherein the extrapolation algorithm comprises linear extension derived from a fuel sensor curve over the range. 
   
   
       4 . The apparatus according to  claim 1 , wherein the extrapolation algorithm comprises a mathematical function derived from selected points on a fuel sensor curve over the range. 
   
   
       5 . The apparatus according to  claim 1 , wherein the controller utilizes the extrapolation algorithm to provide a predetermined rate leaner or with excess air than a stoichiometric ratio of air to fuel. 
   
   
       6 . The apparatus according to  claim 1 , wherein the controller utilizes the extrapolation algorithm to provide a predetermined rate richer or with excess fuel than a stoichiometric ratio of air to fuel. 
   
   
       7 . The apparatus according to  claim 1 , wherein the fuel sensor comprises a pressure sensor. 
   
   
       8 . The apparatus according to  claim 1 , wherein the fuel sensor comprises a mass flow sensor, a volumetric flow sensor, or combinations thereof. 
   
   
       9 . The apparatus according to  claim 1 , wherein the fuel sensor comprises an anemometer, a turbine, an orifice, a venturi, a nozzle, or combinations thereof. 
   
   
       10 . The apparatus according to  claim 1 , wherein the combustion air device comprises full modulation operation between a minimum of the extrapolation algorithm and a full system capacity. 
   
   
       11 . The apparatus according to  claim 1 , wherein controller maximizes burner efficiency. 
   
   
       12 . The apparatus according to  claim 1 , wherein the controller maintains a target efficiency over an entire operating range. 
   
   
       13 . The apparatus according to  claim 1 , wherein the controller maximizes turn down. 
   
   
       14 . The apparatus according to  claim 1 , wherein the controller minimizes carbon monoxide, excess oxygen, nitrogen oxides, or combinations thereof. 
   
   
       15 . The apparatus according to  claim 1 , wherein the controller learns from a flame-out due to low combustion fuel and modifies the extrapolation algorithm for future use upward to prevent additional flame-outs. 
   
   
       16 . The apparatus according to  claim 1 , further comprising:
 a first burner with a capacity; and   one or more additional burners each with a capacity and with the first burner forming a sequentially staged burner system;   wherein the controller communicates with the first burner and the one or more additional burners when a heating demand exceeds the capacity of the first burner the controller activates the one or more additional burners.   
   
   
       17 . The apparatus according to  claim 16 , wherein the controller uses a sequential algorithm modulating the first burner to provide continuous modulation operation over a system range. 
   
   
       18 . The apparatus according to  claim 16 , wherein the controller uses a sequential algorithm modulating the first burner and the one or more additional burners to provide continuous modulation operation over a system range. 
   
   
       19 . The apparatus according to  claim 16 , further comprising a second sequentially staged burner system to provide a broader system range. 
   
   
       20 . The apparatus according to  claim 1 , further comprising a flue gas sensor indicating a flue gas characteristic. 
   
   
       21 . The apparatus according to  claim 20 , wherein the flue gas sensor comprises a temperature sensor, a carbon monoxide sensor, an oxygen sensor, nitrogen oxide sensor, or combinations thereof. 
   
   
       22 . A combustion apparatus for use in fired variable demand applications, the apparatus comprising:
 a fuel valve modulating a fuel flow;   a fuel sensor with a range measuring the fuel flow and sending a fuel output;   a variable speed driver modulating an air flow of a combustion air device;   a damper modulating the air flow of the combustion air device;   an air sensor measuring the air flow and sending an air output; and   a controller connected to the fuel valve, the fuel sensor, the variable speed driver, the damper, and the air sensor, the controller modulating the fuel valve based on the fuel output, the controller modulating the variable speed driver and the damper based on the air output;   wherein the controller simultaneously or sequentially modulates the fuel flow and the air flow over an extended fuel/air ratio and provides continuous modulation during a single burn cycle.   
   
   
       23 . The apparatus according to  claim 22 , wherein the fuel sensor comprises a pressure sensor. 
   
   
       24 . The apparatus according to  claim 22 , wherein the fuel sensor comprises a mass flow sensor, a volumetric flow sensor, or combinations thereof. 
   
   
       25 . The apparatus according to  claim 22 , wherein the fuel sensor comprises an anemometer, a turbine, an orifice, a venturi, a nozzle, or combinations thereof. 
   
   
       26 . The apparatus according to  claim 22 , wherein the combustion air device comprises full modulation operation. 
   
   
       27 . The apparatus according to  claim 22 , wherein controller maximizes burner efficiency. 
   
   
       28 . The apparatus according to  claim 22 , wherein the controller maintains a target efficiency over an entire operating range. 
   
   
       29 . The apparatus according to  claim 22 , wherein the controller maximizes turn down. 
   
   
       30 . The apparatus according to  claim 22 , wherein the controller minimizes carbon monoxide, excess oxygen, nitrogen oxides, or combinations thereof. 
   
   
       31 . A method of operating a combustion apparatus for use in fired variable demand applications, the method comprising:
 measuring a fuel flow with a fuel sensor having a range and a fuel output;   measuring an air flow with an air sensor having an air output;   modulating the fuel flow with a fuel valve and a controller based on the fuel output;   modulating the air flow with a combustion air device and the controller based on the air output;   calculating the air flow or the fuel flow when the fuel output extends outside of the range of the fuel sensor with an extrapolation algorithm; and   maintaining simultaneously or sequentially the fuel flow and the air flow over an extended fuel/air ratio and to provide continuous modulation during a single burn cycle with the controller.   
   
   
       32 . The method according to  claim 31 , wherein the extrapolation algorithm comprises fuzzy logic, linear extension, a mathematical function, or combinations thereof. 
   
   
       33 . The method according to  claim 31 , wherein the maintaining comprises a stoichiometric ratio, a lean ratio, or a rich ratio. 
   
   
       34 . The method according to  claim 31 , wherein the modulating the air flow and modulating the fuel flow comprise maximum burner efficiency, target efficiency over an entire operating range, or maximum turndown. 
   
   
       35 . The method according to  claim 31 , wherein the maintaining further comprises minimizing carbon monoxide, excess oxygen, nitrogen oxides, or combinations thereof. 
   
   
       36 . A method of operating a combustion apparatus for use in fired variable demand applications, the method comprising:
 measuring a fuel flow with a fuel sensor having a range and a fuel output;   measuring an air flow with an air sensor having an air output;   modulating the fuel flow with a fuel valve and a controller based on the fuel output;   modulating the air flow with a damper and a variable speed driver of a combustion air device and the controller based on the air output; and   maintaining simultaneously or sequentially the fuel flow and the air flow over an extended fuel/air ratio and to provide continuous modulation during a single burn cycle with the controller.   
   
   
       37 . The method according to  claim 36 , wherein the modulating the air flow and modulating the fuel flow comprise maximum burner efficiency, target efficiency over an entire operating range, or maximum turndown. 
   
   
       38 . The method according to  claim 36 , wherein the maintaining further comprises minimizing carbon monoxide, excess oxygen, nitrogen oxides, or combinations thereof.