Method of operating a staged-air vortex burner

Claim 2

A staged-air vortex burner for use in burning low heating value fuel and under forced-draft service, comprising a flame zone; a swirl chamber (29) for creating a swirling flow path for primary combustion air and primary low heating value fuel; means (33, 37) for introducing primary combustion air and low heating value fuel into the swirl chamber (29) and from there to said flame zone; and means (48, 46) adjacent to each other for introducing secondary air and secondary low heating value fuel so as to intersect the flame zone at a point such that the secondary air and secondary low heating value fuel have minimal effect on the aerodynamics of the flame.

Claim 3

A burner as claimed in claim 1, wherein said means (48, 46) adjacent to each other for introducing secondary air and secondary low heating value fuel is positioned so that the secondary air and secondary low heating value fuel intersect the flame zone above the region of the recirculating core of the flame.

Claim 4

A burner as claimed in claim 2, wherein said means (48, 46) for introducing secondary low heating value fuel and secondary air comprises an annular gap (44) surrounding the flame zone.

Claim 5

A burner as claimed in claim 3, including a common plenum chamber (20) for said primary and said secondary air and a common plenum chamber (34) for said primary and secondary low heating value fuel, said air and said low heating value fuel plenum chambers (20, 34) having openings communicating with said swirl chamber (29) and said annular gap (44) such that a predetermined ratio of air and low heating value fuel is fed into said swirl chamber (29) and into said annular gap (44).

Claim 6

A burner as claimed in an preceding claim, including an auxiliary fuel supply means (31, 32 ) positioned to discharge auxiliary fuel in said swirl chamber (29).

Claim 7

A staged-air vortex burner for use in burning low heating value fuels under forced-draft service and adapted to be mounted in a furnace having an opening therein, comprising, in combination: a burner casing (22) defining a first plenum chamber (20); a conduit (26) opening into said first plenum chamber (20) for forcing air therein; a swirl chamber (29) having an upper section and a lower section and being centrally disposed within said first plenum chamber (20); a plurality of conduits (33) communicating with said first plenum chamber (20) and said lower section of said swirl chamber (29), whereby air forced into said first plenum chamber (20) enters into said swirl (29) chamber in a swirling flow path; a second plenum chamber (34) disposed within said first plenum chamber (20) and around the upper end of said swirl chamber (29); a conduit for introducing low heating value fuel into said second plenum chamber (34); a plurality of conduits (37) communicating with the second plenum chamber (34) and said swirl chamber (29), whereby low heating value fuel introduced into said second said plenum chamber (34) enters into said swirl chamber (29) in a swirling flow path; a flame zone; an outlet at one end of said swirl chamber (29) for discharging said swirling air and said swirling low heating value fuel into said flame zone; an annular refractory tile (41, 42) surrounding said flame zone; a uniform annular gap (44) in said refractory tile; and means (48, 46) for introducing secondary low heating value fuel and secondary air adjacent each other and through said uniform annular gap (44), said gap (44) being positioned with respect to said outlet of said swirl chamber (29) and said flame zone whereby said secondary air and secondary low heating value fuel introduced through said annular gap (44) enters the flame zone above the region of the circulating core of the flame therein.

Claim 8

A staged-air vortex burner for use in burning low heating value fuels under forced-draft service and adapted to be mounted in a furnace having an opening therein, comprising, in combination: a burner casing (22) defining a first plenum chamber (20); a conduit (26) opening into said first plenum chamber (20) for forcing air therein; a swirl chamber (29) having an upper section and a lower section and being centrally disposed within said first plenum chamber (20); a plurality of conduits (33) communicating with said first plenum chamber (20) and said lower section of said swirl chamber (29), whereby air forced into said first plenum chamber (20) enters into said swirl (29) chamber in a swirling flow path; a second plenum chamber (34) disposed within said first plenum chamber (20) and around the upper end of said swirl chamber (29); a conduit for introducing low heating value fuel into said second plenum chamber (34); a plurality of conduits (37) communicating with the second plenum chamber (34) and said swirl chamber (29), whereby low heating value fuel introduced into said second said plenum chamber (34) enters into said swirl chamber (29) in a swirling flow path; a flame zone; an outlet at one end of said swirl chamber (29) for discharging said swirling air and said swirling low heating value fuel into said flame zone; an annular refractory tile (41, 42) surrounding said flame zone; a uniform annular gap (44) in said refractory tile; and means (48, 46) for introducing secondary low heating value fuel and secondary air adjacent each other and through said uniform annular gap (44), said gap (44) being positioned with respect to said outlet of said swirl chamber (29) and said flame zone whereby said secondary air and secondary low heating value fuel introduced through said annular gap (44) enters the flame zone above the region of the circulating core of the flame therein.

Claim 9

A burner as claimed in claim 6, including a conduit (31) for introducing an auxiliary fuel into said swirl chamber (29).

Claim 10

A burner as claimed in claim 6 or 7, wherein said means (48, 46) for introducing secondary low heating value fuel into said annular gap (44) comprises a wall member (40a) separating said second plenum chamber and said annular gap, said wall member (40a) having a plurality of slots along the top edge of said wall member through which said low heating value fuel passes into said annular gap (44).