Exhaust recirculating method and apparatus for a hydrocarbon fired burner

Abstract

A system and method for reducing NO x emissions in a hydrocarbon fired burned is provided. The method and apparatus selectively recirculate exhaust gases from the burner into the burner inlet gases to achieve a desired NO x output.

1 . A system for a hydrocarbon fired burner comprising: 
 an exhaust conduit in fluid communication with the burner;    a recirculation conduit configured to provide, fluid communication between the exhaust conduit and burner inlet;    an adjustable valve configured to selectively permit the recirculation conduit to provide fluid communication between the exhaust conduit and the burner inlet;    a NOx sensor located in the exhaust conduit;    a system controller operably connected to the NOx sensor and configured to monitor an amount of NOx emissions in the exhaust conduit, the system controller also operably connected to the valve to adjust the valve; and    a burner controller operably connected to the system controller, wherein the system controller sends a signal to the burner controller to shut down the burner when the NOx emissions in the exhaust conduit are at a first unacceptable level.    
   
   
       2 . The system of  claim 1 , wherein the sensor is located upstream from the recirculation conduit.  
   
   
       3 . The system of  claim 1 , further comprising a database operably connected to the system controller, wherein the system controller sends NOx information received from the NOx sensor to the database for storage.  
   
   
       4 . (canceled).  
   
   
       5 . The system of  claim 1 , wherein the system controller activates an alarm when the NOx emissions in the exhaust conduit are at a predetermined level.  
   
   
       6 . The system of  claim 1 , wherein the valve is a solenoid valve.  
   
   
       7 . The system of  claim 1 , wherein the system controller includes a microprocessor.  
   
   
       8 . The system of  claim 1 , wherein the system controller adjusts the valve to permit more exhaust gas enter to the burner inlet when the NOx emissions in the exhaust conduit are at a predetermined level.  
   
   
       9 . The system of  claim 1 , wherein the valve is associated with a digital processor and a system memory.  
   
   
       10 . A system for a hydrocarbon fired burner comprising: 
 means for exhausting combustion gases in fluid communication with the burner;    means for recirculating combustion gases from the exhausting means with the burner;    means for selectively permitting the recirculation means to provide fluid communication between the exhausting mean and the burner;    means for sensing NOx located in the exhausting means; means for controlling the system operably connected to the NOx sensing means and configured to monitor an amount of NOx emissions in the exhausting means, the controlling means also operably connected to control the permitting means; and    a data storing means operably connected to the system controlling means, wherein the system controlling means sends NOx information received from the NOx sensing means to the data storing means.    
   
   
       11 . The system of  claim 10 , wherein the sensing means is located upstream from the recirculating means.  
   
   
       12 . (canceled).  
   
   
       13 . The system of  claim 10 , further comprising means for controlling the burner operably connected to the system controlling means, wherein the system controlling means sends a signal to the burner controlling means to shut down the burner when the NOx emissions in the exhausting means are at an unacceptable level.  
   
   
       14 . The system of  claim 10 , wherein the system controlling means activates an alarm when the NOx emissions in the exhausting means are at an unacceptable level.  
   
   
       15 . The system of  claim 10 , wherein the permitting means includes a solenoid valve.  
   
   
       16 . The system of  claim 10 , wherein the system controlling means includes a microprocessor.  
   
   
       17 . The system of  claim 10 , wherein the system controlling means adjusts the permitting means to permit more exhaust gas enter to a burner inlet when the NOx emissions in the exhausting means are at an unacceptable level.  
   
   
       18 . A method of reducing NOx emissions in an appliance having a burner comprising: 
 detecting NOx emissions in exhaust associated with the burner;    determining if a recirculation valve should be one of: opened, closed, and remain the same according to predetermined criteria; and    performing one of adjusting the valve and leaving the valve in a current position in accordance with the result of the determining step.    
   
   
       19 . The method of  claim 18 , further comprising saving results obtained from the detecting step.  
   
   
       20 . The method of  claim 18 , further comprising at least one of: 
 shutting down the burner, activating an alarm, and notifying maintenance personnel when the NOx emissions are above an acceptable level.