System for increasing flue gas side draft of heater assemblies using a draft booster impeller assembly

Abstract

A system for increasing flue gas side draft in a heater or boiler assembly is disclosed utilizing an impeller assembly to enable an increase in firing rates beyond the ability of the exhaust stack and to reduce the size of the low flue gas side pressure drop heat pipe air preheaters.

1 . A system for increasing flue gas side draft in a heater assembly, wherein the heater assembly includes a heater, an inlet supply of combustion air, an exhaust flue gas duct and an exhaust stack, wherein flue gas produced in the heater exits the heater through the exhaust duct and stack, the system comprising:
 an impeller assembly operatively coupled to one of the exhaust flue gas duct and the exhaust stack, wherein operation of the impeller assembly increases flue gas draft in the heater assembly to enable an increase in firing rate within the heater beyond the ability of the exhaust stack.   
     
     
         2 . The system according to  claim 1 , wherein heater assembly further includes a low flue gas side pressure drop air preheater and associated ducting for preheating at least a portion of the combustion air, at least a portion of the flue gas and the combustion air are directed to the air preheater, wherein at least a portion of the impeller assembly is located within the exhaust flue gas duct. 
     
     
         3 . The system according to  claim 1 , wherein the impeller assembly includes a motor and an axial impeller. 
     
     
         4 . The system according to  claim 3 , wherein the heater is one of a fired heater and a boiler. 
     
     
         5 . The system according to  claim 3 , wherein the impeller assembly includes an axial impeller. 
     
     
         6 . The system according to  claim 5 , wherein the axial impeller and the motor are located within the exhaust flue gas duct. 
     
     
         7 . The system according to  claim 6 , further comprising a pressurized bearing lubrication system to enable operation in high temperature environments. 
     
     
         8 . The system according to clam  5 , wherein the axial impeller is located within the flue gas duct and the motor is located externally of the exhaust flue gas duct, wherein the impeller assembly furthers include a seal located within a wall of the exhaust flue gas duct and a shaft passing through the seal, wherein the axial impeller and the motor are operatively connected via the shaft. 
     
     
         9 . The system according to  claim 5 , wherein the axial impeller includes one of a gear box or a plurality of variable vanes, such that angle of the vanes can be adjusted. 
     
     
         10 . The system according to  claim 9 , wherein adjustment of one of the gear box or plurality of vanes can adjust the flue gas side draft. 
     
     
         11 . The system according to  claim 1 , wherein a draft created from the impeller is less than 1.5 inch of water column of pressure gain.