Burner Device with Primary Air Chamber, Staged Air Chamber, and Tertiary Air Chamber

Abstract

Disclosed is a staged-air burner device capable of high energy efficiency, high flame stability, combusting multiple readily switchable fuels ranging from pure hydrogen, to any hydrogen/methane mixture, to pure methane, and generating a low level of NOx. The burner device can include: a primary air chamber receiving a primary air and a flue gas; a burner tube capable of receiving a fuel jet and drawing in the air-flue gas mixture from the primary air chamber; a burner tip discharging the fuel-air-flue gas mixture formed in the burner tube to a first combustion zone and a second combustion zone via center orifices and side orifices on the burner tip, respectively; and a staged air chamber receiving staged air and discharging it via staged air ports into a third combustion zone. Combustion of the fuel occurs in at least one of the first, second, and third combustion zones.

1 . A burner device for combusting a fuel in a furnace enclosure, the burner device comprising:
 a primary air chamber configured to receive a primary air and a flue gas to form an air-flue gas mixture in the primary air chamber;   a staged air chamber configured to receive a staged air;   a tertiary air chamber configured to receive a tertiary air;   a burner tube having a first tube end and a second tube end, the first tube end configured to receive the air-flue gas mixture from the primary air chamber and a fuel to form a fuel-air-flue gas mixture in the burner tube;   a burner tip downstream of the second tube end, the burner tip having center orifices and side orifices, the burner tip configured to discharge a first portion of the fuel-air-flue gas mixture into a first combustion zone in the furnace enclosure via the center orifices and a second portion of the fuel-air-flue gas mixture into a second combustion zone in the furnace enclosure via the side orifices, respectively;   one or more staged air ports configured to discharge the staged air from the staged air chamber into a third combustion zone in the furnace enclosure; and   a tile adjacent to the burner tip configured to form a tile-burner tip gap between the burner tip and the tile, the tile-burner tip gap being in fluid communication with the tertiary air chamber and capable of discharging the tertiary air into the second combustion zone.   
     
     
         2 . The burner device of  claim 1 , further comprising:
 a flue gas recirculation (FGR) duct configured to receive the flue gas from the furnace enclosure; and   a heat exchanger configured to (i) receive the staged air or a portion thereof; (ii) receive the flue gas or a portion thereof from the FGR duct, wherein the flue gas before entering the heat exchanger has a higher temperature than the staged air before entering the heat exchanger; (iii) exchange heat between the flue gas and the staged air; (iv) discharge a cooled flue gas into the primary air chamber; and (v) discharge a heated staged air into the staged air chamber.   
     
     
         3 . The burner device of  claim 2 , wherein:
 the burner device comprises a fuel supply tube capable of supplying the fuel into the burner tube as a fuel jet; and   the burner tube comprises a venturi segment, and the venturi segment includes a diverging outlet with an inner fluid channel that has an increasing size along a flow direction of the fuel-air-flue gas mixture in the venturi segment.   
     
     
         4 . The burner device of  claim 1 , wherein:
 the burner device further comprises a steam supply tube capable of supplying a steam into the burner tube such that the fuel-air-flue gas mixture comprises steam.   
     
     
         5 . The burner device of  claim 4 , wherein the steam supply tube has an end inserted into or just upstream of the first tube end of the burner tube. 
     
     
         6 . The burner device of  claim 2 , further comprising one or more bleed air ducts configured to channel a bleed air into the FGR duct at a bleed air inlet location upstream of the heat exchanger relative to a flow of the flue gas in the FGR duct. 
     
     
         7 . The burner device of  claim 6 , further comprising one or more mixing elements disposed in the FGR duct downstream of the bleed air inlet location and upstream of the heat exchanger relative to the flow of the flue gas in the FGR duct, the one or more mixing elements adapted for mixing the bleed air and the flue gas. 
     
     
         8 . The burner device of  claim 7 , wherein the one or more mixing elements comprise one or more chevron mixers. 
     
     
         9 . The burner device of  claim 6 , wherein the one or more bleed air ducts comprises a bleed air inlet fitted with one or more machined inserts each having a predefined opening size adapted for controlling a flow rate of the bleed air. 
     
     
         10 . The burner device of  claim 1 , wherein the one or more staged air ports extends through a furnace floor, or a furnace roof, or a furnace wall of the furnace enclosure. 
     
     
         11 . The burner device of  claim 1 , further comprising a tertiary air inlet coupled to the tertiary air chamber, wherein the tertiary air inlet comprises a tertiary air inlet damper and a tertiary air damper stopper, the tertiary air damper stopper configured to allow a flow of tertiary air no less than a threshold required for a stable burner flame. 
     
     
         12 . The burner device of  claim 1 , further comprising at least one of the following:
 a staged air inlet comprising a staged air inlet damper and in fluid communication with the heat exchanger and/or the staged air chamber; and   a primary air inlet comprising a primary air inlet damper and coupled to the primary air chamber.   
     
     
         13 . A process for combusting a fuel using the burner device of  claim 1 . 
     
     
         14 . A furnace including the burner device of  claim 1 , wherein the furnace is a steam cracking furnace, a steam-hydrocarbon reforming furnace, or a steam boiler furnace. 
     
     
         15 . The furnace of  claim 14 , which is the steam cracking furnace comprising a radiant section including a radiant tube and the burner device, wherein the radiant tube is in proximity to the burner device, such that the thermal energy released by combusting the fuel by the burner device is capable of heating the radiant tube. 
     
     
         16 . The furnace of  claim 15 , further comprising more than one of the burner device and more than one of the radiant tube. 
     
     
         17 . The furnace of  claim 15 , wherein a portion of the burner device extends through a floor of the furnace enclosure. 
     
     
         18 . The furnace of  claim 14 , which is a hydrocarbon-steam reforming furnace, wherein a portion of the burner device extends through a side wall or a roof of a housing of the furnace. 
     
     
         19 . A process for combusting a fuel in a furnace comprising a furnace enclosure and a burner device, wherein the burner device comprises a primary air chamber, a staged air chamber, a tertiary air chamber, a burner tube having a first tube end and a second tube end, and a burner tip having center orifices and side orifices coupled to the second tube end, a tile in proximity to the burner tip defining a tile-burner tip gap between the tile and the burner tip, the first tube end is in fluid communication with the primary air chamber, the furnace enclosure is in fluid communication with the staged air chamber via one or more staged air ports, the furnace enclosure is in fluid communication with the tertiary air chamber via the tile-burner tip gap, and the process comprises:
 supplying a primary air and a flue gas into the primary air chamber to form an air-flue gas mixture in the primary air chamber;   supplying a staged air into the staged air chamber;   supplying a tertiary air into the tertiary air chamber;   supplying the fuel into the first tube end;   receiving the air-flue gas mixture via the first tube end into the burner tube to mix with fuel to form a fuel-air-flue gas mixture in the burner tube;   discharging a first portion of the fuel-air-flue gas mixture into a first combustion zone in the furnace enclosure via the center orifices of the burner tip;   discharging a second portion of the fuel-air-flue gas mixture into a second combustion zone in the furnace enclosure via the side orifices of the burner tip;   discharging the tertiary air into the second combustion zone via the tile-burner tip gap;   discharging the staged air from the staged air chamber into a third combustion zone in the furnace enclosure via the one or more staged air ports; and   combusting the fuel in at least one of the first combustion zone, the second combustion zone, and the third combustion zone.   
     
     
         20 . The process of  claim 19 , wherein the burner device comprises a flue gas recirculation (FGR) duct for channeling the flue gas from the furnace enclosure into the primary air chamber and a heat exchanger, the heat exchanger is configured to (i) receive the staged air or a portion thereof; (ii) receive the flue gas or a portion thereof from the FGR duct; (iii) exchange heat between the flue gas and the staged air; (iv) discharge a cooled flue gas into the primary air chamber; and (v) discharge a heated staged air into the staged air chamber; and the process comprises:
 receiving the flue gas from the furnace enclosure into the FGR duct; 
 receiving the flue gas into the heat exchanger from the FGR duct; 
 receiving the staged air into the heat exchanger, wherein the staged air has a temperature lower than the flue gas; 
 exchanging heat between the flue gas and the staged air in the heat exchanger; 
 discharging the cooled flue gas into the primary air chamber; and 
 discharging a heated staged air into the staged air chamber. 
 
     
     
         21 . The process of  claim 19 , wherein:
 the burner tube comprises a venturi segment, and the venturi segment includes a diverging outlet with an inner fluid channel that has an increasing size along a flow direction of the fuel-air-flue gas mixture in the venturi segment; and the process comprises:   injecting the fuel into the first tube end as a fuel jet.   
     
     
         22 . The process of  claim 19 , further comprising:
 supplying a steam into the first tube end such that the fuel-air-flue gas mixture comprises steam.   
     
     
         23 . The process of  claim 19 , wherein at least a portion of the primary air is supplied to the primary air chamber via a primary air inlet comprising an adjustable primary air inlet damper. 
     
     
         24 . The process of  claim 20 , further comprising:
 supplying a bleed air into the FGR duct via a bleed air duct and at a bleed air inlet location upstream of the heat exchanger relative to a flow of the flue gas in the FGR duct, wherein the bleed air constitutes at least a portion of the primary air supplied into the primary air chamber; and   mixing the flue gas and the bleed air in the FGR duct via one or more mixing elements disposed in the FGR duct downstream of the bleed air inlet location and upstream of the heat exchanger relative to the flow of the flue gas in the FGR duct.   
     
     
         25 . The process of  claim 24 , further comprising:
 controlling a flow rate of the bleed air by using a machined metal insert having a predetermined dimension at the bleed air inlet location.   
     
     
         26 . The process of  claim 24 , wherein the bleed air constitutes at least 80%, by volume, of the primary air supplied into the primary air chamber. 
     
     
         27 . The process of  claim 24 , further comprising:
 closing the primary air inlet damper, such that the bleed air constitutes substantially all of the primary air supplied into the primary air chamber.   
     
     
         28 . The process of  claim 19 , further comprising receiving the tertiary air via a tertiary air inlet coupled to the tertiary air chamber, wherein the tertiary air inlet comprises a tertiary air inlet damper and a tertiary air damper stopper, the tertiary air damper stopper configured to allow a flow of the tertiary air no less than a threshold required for a stable burner flame. 
     
     
         29 . The process of  claim 19 , further comprising:
 during a first time interval, supplying the fuel into the first tube end;   at the end of the first time interval, switching the fuel to an alternate fuel differing from the fuel; and   during a second time interval immediately after the first time interval, supplying the alternate fuel into the first tube end.   
     
     
         30 . The process of  claim 29 , wherein:
 the fuel comprises hydrogen at a concentration of at least 80 mol %, based on the total moles in the fuel; and   the alternate fuel comprises methane at a concentration of at least 80 mol %, based on the total moles in the alternate fuel.   
     
     
         31 . The process of  claim 30 , further comprising:
 engaging the tertiary air inlet damper with the tertiary air damper stopper at the end of the first time interval and/or at least partly during the second time interval, while maintaining a stable flame in the furnace enclosure.   
     
     
         32 . The process of  claim 19 , wherein the fuel comprises hydrogen at a concentration of at least 90 mol %, based on the total moles in the fuel. 
     
     
         33 . The process of  claim 29 , wherein:
 the fuel comprises methane at a concentration of at least 80 mol %, based on the total moles in the fuel; and   the alternate fuel comprises hydrogen at a concentration of at least 80 mol %, based on the total moles in the alternate fuel.   
     
     
         34 . The process of  claim 19 , further comprising at least one of the following:
 receiving the staged air via a staged air inlet comprising a staged air inlet damper and in fluid communication with the heat exchanger and/or the staged air chamber.   
     
     
         35 . The process of  claim 19 , further comprising:
 reducing a flow rate of the primary air through the primary air inlet into the primary air chamber.   
     
     
         36 . The process of  claim 35 , comprising closing the adjustable primary air inlet damper in the primary air inlet.