Method for controlling lean combustion stability

Abstract

A method for eliminating or substantially reducing unstable combustion conditions within a combustion chamber. By adding hydrogen to the inlet fuel mixture, the method provides a means for altering the overall combustion (reaction) rate and the resulting characteristic reaction time that, in turn, will eliminate or substantially reduce undesirable pressure oscillations. Moreover, the invention provides a low cost and easily installed method for active control of pressure oscillations within a combustion chamber

We claim:  
     
         1 . A method for active control of combustion oscillations within a combustion chamber, comprising the step of: 
 adding hydrogen to the inlet fuel mixture provided to the combustion chamber in an amount sufficient to eliminate pressure oscillations.    
     
     
         2 . The method of  claim 1 , wherein the inlet fuel mixture contains a base hydrocarbon fuel including natural gas, methane, coal gas, biomass-derived fuel, or other hydrocarbon fuel materials  
     
     
         3 . A method for eliminating unstable combustion conditions within a combustion chamber, comprising the steps of: 
 determining the stability characteristics of the combustion chamber as a function of hydrogen concentration for a given value of inlet fuel flow rate and equivalence ratio;    establishing an operating point for the combustor; and    adding hydrogen to the inlet fuel mixture provided to the combustion chamber in an amount sufficient to eliminate pressure oscillations.    
     
     
         4 . The method of  claim 3 , wherein the inlet fuel mixture contains a base hydrocarbon fuel including natural gas, methane, coal gas, biomass-derived fuel, or other hydrocarbon fuel materials  
     
     
         5 . A method for the active control of pressure oscillations within a combustion chamber, comprising: 
 measuring the amplitude of pressure fluctuations within a combustion chamber; and    providing a inlet fuel mixture comprising a base hydrocarbon fuel, air, and hydrogen to the combustion chamber, wherein the concentration of hydrogen is in an amount sufficient to eliminate or substantially reduce pressure fluctuations.    
     
     
         6 . The method of  claim 5 , wherein the base hydrocarbon fuel includes natural gas, methane, coal gas, biomass-derived fuel, or other hydrocarbon fuel materials