EXCESS AIR FUEL / GAS BURNER - 3422
EXCESS AIR FUEL / GAS BURNER - 3422
Xcel Air Fuel / Gas Burner – 3422 3422 Fire All Dual-Fuel Burners are commonly used on heat treat and non-ferrous melting furnaces, kilns, ovens, air heaters, dryers, chemical process equipment, and other applications where superior temperature uniformity is required. These sealed-in, nozzle-mix burners for gas and/or distillate oil are stable on stoichiometric ratio, with large amounts of Xces air, or with up to 50% Xces fuel (provided additional air for combustion is in the furnace near the burner).
Burners can be lighted at rich, lean, or correct air/fuel ratio, then immediately turned to high fire. Required gas pressures are low: 2”wg at the burner for coke oven gas, less for natural gas. Required oil pressure at the burner is nearly zero, but a pressure drop of about 10psi should be taken across the Precise OilControl Valve.
The most common ratio control system for 3422 Burners uses a cross-connectedregulator and Ratio Controller. When appropriate for the application, flow balancing systems or fuel only control (see “Xces Air” paragraph) is very satisfactory. If furnace temperatures after shutdown rise above 1000oC, pass some air through burner to prevent overheating. During gas operation, use at least 7”wg atomizing air to cool atomizer (full atomizing air may be used); or for extended periods of operation on gas, atomizer can be withdrawn and stored: Use a back plate and gasket to seal rear of burner.
LIGHTING / FLAME SUPERVISION
A Pilot Set normally is used to light 3422 Burners. On gas, direct spark ignition of the burner is available. A manual torch can be used in some pplications. Burners accept ultraviolet (UV) scanners for monitoring pilot or main flame. A flame rod can be used to monitor pilot or main gas fire. When using flame supervision, an interrupted pilot is required–do not use constant or intermittent pilots. If using direct spark ignition, turn off spark after burner lights. An observation port is furnished with all burners. Positions of pilot, flame detector, and observation port are interchangeable as long as pilot and flame detector are mounted in adjacent holes.
Xces air can improve temperature uniformity by avoiding hot spots in front of burners, by churning furnace atmosphere to reduce stratification, and by creating positive furnace pressure to eliminate cold air infiltration. Xces air can give very high effective burner turndown. Thus a furnace used for high temperature work (such as heat treating at 1000oC) with burners firing on air/fuel ratio can also be used for low temperature jobs (such as drawing or drying at 300oC) with burners firing on lean ratio.
The 3422 burners can be used with chamber temperatures upto 1100oC. If furnace temperature could rise above 850oC after shutdown, some air should be maintained through the burner to prevent over heating.
Air and gas inlets can be rotated in 90° (both CW & ACW Direction), but air and gas pipes should be brought in from the top or side to prevent oil dripping into them. Mounting plates are cast iron. Burner Blocks are 9″ long for thicker furnace walls, lining beyond end of tile should be flared at least 30° included angle, starting at tile OD. Extension tiles are not recommended. For installation convenience, burner body can be separated from the mounting plate and tile assembly. But burner block must be set in the wall with pilot and flame detector notches in proper location relative to intended burner body position.
JACKETED BURNER BLOCKS: 3422 Burners have a carbon steel jacket around the burner block for applications where there is no furnace refractory to support tiles and where temperatures.
List I. AIR CAPACITIES* Scfh (Standard Cubic Feet per Hour)
|Burner designation||27”wg air at burner|
|* Includes primary and secondary air.|
List II. COMBUSTION AIR CAPACITITES in scfh (not including atomizing air)
|Burner Designation||Air Pressure Drop Across Burner in inches of WGP||Approx. flame lengths in mm with 27”wg Main air (in open furnace)|
List III. ATOMIZING AIR CAPACITITES in scfh
|Burner Designation||Air pressure drop across burner in inches of WGP|