Induced-Draft Burner With Isolated Gas-Air Mixing

Abstract

A furnace with a burner is disclosed. The burner may include an area expansion plenum, a burner tube, a heat exchanger, a gas valve, an igniter, and an induced-draft blower. The gas valve may meter gas into the area expansion plenum, while the induced-draft blower may draw air into the area expansion plenum, wherein air and gas may mix to produce a lean gas/air mixture. The lean gas/air mixture may then be pulled through the burner tube and into the heat exchanger. Within the heat exchanger, the lean gas/air mixture may be ignited and energy may be produced, exciting acoustic energy in the heat exchanger. The acoustic energy may be distributed out of the heat exchanger by the area expansion plenum. In order to distribute the acoustic energy, the cross sectional area of the area expansion plenum may be greater than the cross sectional area of the burner tube.

1 ) A burner for a furnace, comprising:
 an area expansion plenum capable of mixing gas and air to produce a lean gas/air mixture;   a gas valve operatively coupled to the area expansion plenum and capable of metering gas into the area expansion plenum;   a combustion chamber downstream of the area expansion plenum;   a burner tube operatively coupled between the area expansion plenum and the combustion chamber;   an induced-draft blower downstream of the combustion chamber and capable of drawing air into the area expansion plenum, and pulling the lean gas/air mixture through the burner tube and into the combustion chamber; and   an igniter associated between the burner tube and the combustion chamber and capable of igniting the lean gas/air mixture.   
     
     
         2 ) The burner of  claim 1 , wherein the igniter produces a flame upon ignition of the lean gas/air mixture, the flame produces energy in the combustion chamber, the energy excites acoustic energy in the combustion chamber, and wherein the area expansion plenum provides a fluid communication path to distribute the acoustic energy out of the combustion chamber. 
     
     
         3 ) The burner of  claim 1 , wherein the combustion chamber is part of a heat exchanger. 
     
     
         4 ) The burner of  claim 1 , wherein a cross sectional area of the area expansion plenum is greater than a cross sectional area of the burner tube. 
     
     
         5 ) The burner of  claim 4 , wherein the cross sectional area of the area expansion plenum is at least ten times greater than the cross sectional area of the burner tube. 
     
     
         6 ) The burner of  claim 1 , wherein the area expansion plenum has one of a concave and convex surface. 
     
     
         7 ) The burner of  claim 1 , wherein the area expansion plenum is oriented in a vertical position. 
     
     
         8 ) The burner of  claim 1 , wherein the area expansion plenum is oriented in an axial position. 
     
     
         9 ) A method for isolating gas-air mixing in an induced-draft burner, comprising the steps of:
 metering gas into an area expansion plenum;   drawing air into the area expansion plenum;   mixing gas and air within the area expansion plenum to produce a lean gas/air mixture;   pulling the lean gas/air mixture through a burner tube and into a heat exchanger;   igniting the lean gas/air mixture within the heat exchanger, the ignition producing energy in the heat exchanger, the energy exciting acoustic energy in the heat exchanger; and   distributing the acoustic energy in the heat exchanger out of the heat exchanger and into the area expansion plenum.   
     
     
         10 ) The method of  claim 9 , wherein a cross sectional area of the area expansion plenum is greater than a cross sectional area of the burner tube. 
     
     
         11 ) The method of  claim 10 , wherein the cross sectional area of the area expansion plenum is at least ten times greater than the cross sectional area of the burner tube. 
     
     
         12 ) The method of  claim 10 , wherein the acoustic energy distribution rate increases as the area ratio of the area expansion plenum to the burner tube increases. 
     
     
         13 ) The method of  claim 9 , wherein air is drawn by an induced-draft blower into the area expansion plenum and gas is metered by a gas valve into the area expansion plenum to produce the lean gas/air mixture, the lean gas/air mixture being pulled by the induced-draft blower through the burner tube and into the heat exchanger. 
     
     
         14 ) A furnace with a burner, comprising:
 at least one area expansion plenum capable of mixing gas and air to produce a lean gas/air mixture;   a gas valve operatively associated with the area expansion plenum and capable of metering gas into the area expansion plenum;   at least one heat exchanger downstream of the area expansion plenum;   at least one burner tube operatively coupled between the area expansion plenum and the heat exchanger;   an induced-draft blower downstream of the heat exchanger and capable of drawing air into the area expansion plenum, and pulling the lean gas/air mixture through the burner tube and into the heat exchanger; and   an igniter associated between the burner tube and the heat exchanger and capable of igniting the lean gas/air mixture to produce combustion products;   a flue pipe downstream of the induced-draft blower, wherein the induced-draft blower is adapted to pull the combustion products through the heat exchanger and push the combustion products through the flue pipe and out into the atmosphere; and   a cabinet housing therein the area expansion plenum, the gas valve, the burner tube, the igniter, the heat exchanger, the induced-draft blower, and the flue pipe.   
     
     
         15 ) The furnace of  claim 14 , wherein a cross sectional area of the at least one area expansion plenum is greater than a cross sectional area of the at least one burner tube. 
     
     
         16 ) The furnace of  claim 15 , wherein the cross sectional area of the at least one area expansion plenum is at least ten times greater than the cross sectional area of the at least one burner tube. 
     
     
         17 ) The furnace of  claim 14 , wherein the at least one area expansion plenum has one of a concave and convex surface. 
     
     
         18 ) The furnace of  claim 14 , wherein the at least one area expansion plenum is oriented in an axial position. 
     
     
         19 ) The furnace of  claim 14 , wherein the at least one area expansion plenum is oriented in a vertical position. 
     
     
         20 ) The furnace of  claim 14 , wherein the igniter produces a flame upon ignition of the lean gas/air mixture, the flame produces energy in the at least one heat exchanger, the energy excites acoustic energy in the at least one heat exchanger, the acoustic energy in the at least one heat exchanger is distributed out of the at least one heat exchanger by the at least one area expansion plenum.