Regenerative burner system and method of use
A method heats a furnace process chamber with the combustion of fuel gas. The method heats the process chamber in a preheat mode when the temperature of the process chamber is below the autoignition temperature of the fuel gas. The preheat mode forms preheated combustion air by directing the combustion air through a regenerative bed. A stream of the preheated combustion air is directed into the process chamber in a condition unmixed with fuel gas. The preheat mode also forms a fuel rich mixture of the fuel gas and unheated combustion air. The fuel rich mixture is directed into the process chamber adjacent to the stream of preheated combustion air.
1. A system, comprising:
a furnace having a process chamber;
a source of fuel gas;
a source of combustion air;
a regenerator including a bed of regenerative material in air flow communication with the source of combustion air, wherein the regenerator has a combustion air plenum with a port configured to direct a stream of combustion air from the bed of regenerative material into the process chamber, and the regenerator is free of a fuel flow structure configured to direct fuel gas into the plenum;
a reactant delivery device in gas flow communication with the source of fuel gas and the source of combustion air, wherein the reactant delivery device is configured to form a combustible mixture of fuel gas and combustion air, and to direct the combustible mixture into the process chamber adjacent to the stream of combustion air; and
a controller configured to initiate, regulate and terminate flows of combustion air and fuel gas to provide combustion for heating the process chamber, wherein the controller is configured to carry out steps of:
a) raising the process chamber to an elevated temperature equal to or greater than an auto-ignition temperature of the fuel gas by heating the process chamber in a preheat mode when the temperature of the process chamber is below the autoignition temperature of the fuel gas, including:
forming preheated combustion air by directing combustion air through a heated regenerative bed;
directing a stream of the preheated combustion air into the process chamber in a condition unmixed with the fuel gas;
forming a fuel rich mixture of the fuel gas and combustion air; and
directing the fuel rich mixture from the reactant delivery device into the process chamber adjacent to the stream of preheated combustion air, whereby the reactant delivery device functions as a burner in the preheat mode; and
b) following the preheat mode, heating the process chamber in an auto-ignition mode when the temperature of the process chamber is at or above the auto-ignition temperature of the fuel gas, including:
forming preheated combustion air by directing combustion air through the heated regenerative bed;
directing a stream of the preheated combustion air into the process chamber in a condition unmixed with fuel gas;
directing the fuel gas from the reactant delivery device into the process chamber in a condition unmixed with combustion air, whereby the reactant delivery device functions as a fuel injector in the auto-ignition mode.
2. The system of claim 1 , wherein the fuel rich mixture is formed of the fuel gas and unheated combustion air.
3. The system of claim 1 , wherein the fuel rich mixture is provided with flame stabilization.
4. The system of claim 1 , further comprising an igniter operatively associated with the fuel delivery structure to ignite the combustible mixture.
5. The system of claim 4 , wherein the controller is further configured to actuate the igniter to ignite the fuel rich mixture.
6. The system of claim 1 , wherein the streams of the preheated combustion air are directed into the process chamber along a first axis, and the fuel rich mixture is directed into the process chamber along a second axis inclined toward the first axis.
7. The system of claim 1 , wherein the reactants directed into the process chamber in the preheat mode consist of combustion air and fuel gas.
8. The system of claim 1 , wherein the reactant delivery device is configured to provide the combustible mixture with flame stabilization.
9. The system of claim 1 , wherein the regenerator is configured to direct the stream of combustion air into the process chamber along a first axis, and the reactant delivery device is configured to direct the combustible mixture into the process chamber along a second axis inclined toward the first axis.