Lean pre-mix radiant wall burner apparatus and method

A radiant wall burner comprising:

• a primary fuel tip assembly comprising
• a longitudinal axis,
• a venturi having a longitudinally rearward inlet end and a longitudinally forward discharge end,
• a radial discharge tip positioned on or forwardly of the longitudinally forward discharge end of the venturi,
• the radial discharge tip having a closed longitudinally forward end and a longitudinally extending side wall which surrounds the longitudinal axis, and
• a longitudinal series of rows of surrounding slots formed through the side wall of the radial discharge tip, each of said rows of surrounding slots surrounding the longitudinal axis and each of said rows of surrounding slots lying in a different plane which is substantially perpendicular to the longitudinal axis such that, when the longitudinal axis is vertically positioned, the surrounding slots in each of said rows of surrounding slots are substantially horizontal;
• a primary fuel ejector which ejects a primary gas fuel stream into the venturi and draws an air stream into the longitudinally rearward inlet end of the venturi which mixes with the primary gas fuel stream to form a pre-mix stream;
• a flow diverter in an interior of the radial discharge tip, the flow diverter comprising a deflecting wall which (i) extends rearwardly in the interior of the radial discharge tip, (ii) converges radially inward toward the longitudinal axis as it extends rearwardly, and (iii) is laterally surrounded by at least some of the rows of surrounding slots;
• and
• a staged fuel discharge tip which discharges a staged gas fuel stream, the staged fuel discharge tip being positioned in an interior of the primary fuel tip assembly longitudinally forward of the primary fuel ejector and longitudinally rearward of the deflecting wall of the flow diverter.

A method of operating a radiant wall burner having a primary fuel tip assembly comprising (i) a longitudinal axis, (ii) a venturi having a longitudinally rearward inlet end and a longitudinally forward discharge end, (iii) a radial discharge tip positioned on or forwardly of the longitudinally forward discharge end of the venturi, (iv) the radial discharge tip having a closed longitudinally forward end and a longitudinally extending side wall which surrounds the longitudinal axis, and (v) the side wall of the radial discharge tip having a longitudinally extending radial discharge segment formed therein which surrounds the longitudinal axis, the method comprising discharging from a longitudinally rearward portion of the radial discharge segment a fuel-lean gas fuel and air mixture comprising more than a stoichiometric amount of oxygen, and discharging from a longitudinally forward portion of the radial discharge segment a fuel rich flow comprising less than a stoichiometric amount of or no oxygen, by:

• ejecting, from a primary fuel ejector, a primary gas fuel stream into the longitudinally rearward inlet end of the venturi, the ejection of the primary gas fuel stream drawing an air stream into the longitudinally rearward inlet end of the venturi which mixes with the primary gas fuel stream to form a lean premix stream;
• forwardly discharging from a staged fuel discharge tip, located in an interior of the primary fuel tip assembly, a staged gas fuel stream, the staged fuel discharge tip being positioned longitudinally forward of the primary fuel ejector and longitudinally rearward of a flow diverter in an interior of the radial discharge tip;
• and
• deflecting, from a deflecting wall of the flow diverter, the lean premix stream and the staged gas fuel stream outwardly, at an angle away from the longitudinal axis, in the interior of the radial discharge tip toward the longitudinally extending radial discharge segment.

A radiant wall burner comprising:

• a primary fuel tip assembly comprising
• a longitudinal axis,
• a venturi having a longitudinally rearward inlet end and a longitudinally forward discharge end,
• a radial discharge tip positioned on or forwardly of the longitudinally forward discharge end of the venturi,
• the radial discharge tip having a longitudinally forward end and a longitudinally extending side wall which surrounds the longitudinal axis, and
• a plurality of surrounding openings, formed through the longitudinally extending side wall of the radial discharge tip, which surround the longitudinal axis;
• a primary fuel ejector which ejects a primary gas fuel stream into the venturi and draws an air stream into the longitudinally rearward inlet end of the venturi which mixes with the primary gas fuel stream to form a pre-mix stream;
• a staged fuel discharge tip which discharges a staged gas fuel stream, the staged fuel discharge tip being positioned in an interior of the primary fuel tip assembly longitudinally forward of the primary fuel ejector and longitudinally rearward of the longitudinally forward end of the radial discharge tip;
• and
• the longitudinally forward end of the radial discharge tip being closed so that all of the pre-mix stream is radially discharged from the surrounding openings formed through the longitudinally extending side wall of the radial discharge tip and all of the staged gas fuel stream is also radially discharged from the surrounding openings formed through the longitudinally extending side wall of the radial discharge tip.