Low-firing rate oxy-fuel flat flame burner with oxygen staging
A flat flame oxy-fuel burner including a gaseous fuel nozzle having a hydraulic diameter D h-NG and a width to height ratio w/a of at least 2; a primary oxidant conduit surrounding the fuel nozzle to form an annular primary oxidant nozzle between the fuel nozzle and the oxidant conduit, the oxidant conduit having a height b, the respective outlet ends of the fuel nozzle and the oxidant nozzle being aligned; and a precombustor extending from the outlet end of the fuel and oxidant nozzles and having a length L and a hydraulic diameter D h ; wherein the ratio L/D h is non-zero and less than or equal to 4; wherein the ratio L/D h-NG , is non-zero and less than or equal to 12; and wherein the dimensions a, b, and w are sized to yield a primary oxidant Reynolds number from 200 to 22,000 during burner is operation at 0.05 to 1 MMBtu/hr.
1. A flat flame oxy-fuel burner comprising:
a gaseous fuel nozzle having an outlet end, a width w, a height a, a hydraulic diameter D h-NG , and a width to height ratio w/a of at least about 2;
a primary oxidant conduit positioned concentrically surrounding the fuel nozzle so as to form a substantially uniform annular primary oxidant nozzle between the fuel nozzle and the primary oxidant conduit, the primary oxidant conduit having a height b, the primary oxidant nozzle having an outlet end aligned with the outlet end of the fuel nozzle; and
a precombustor extending from the outlet end of the fuel and oxidant nozzles to a flame end, the precombustor having a length L, and a hydraulic diameter D h ;
wherein the ratio L/D h of the precombustor is greater than 0 and less than or equal to about 4;
wherein the precombustor length normalized by the hydraulic diameter of the fuel nozzle L/D h-NG is greater than 0 and less than or equal to about 12; and
wherein the dimensions a, b, and w, are sized such that the primary oxidant has a Reynolds number from about 200 to about 22,000 when the burner is operated at a firing rate of about 0.05 to about 1 MMBtu/hr; and
wherein the width w of the fuel nozzle is from about 1 to about 2 inches.
2. The oxy-fuel burner of claim 1 , wherein the ratio of w to a is from about 2 to about 60.
3. The oxy-fuel burner of claim 2 , wherein the ratio of w to a is from about 5 to about 30.
4. The oxy-fuel burner of claim 1 , wherein the length L of the precombustor is greater than 0 inches and less than about 4 inches.
5. The oxy-fuel burner of claim 4 , wherein the length L of the precombustor is from about 0.5 to about 2 inches.
6. The oxy-fuel burner of claim 1 , wherein the precombustor has a divergent geometry and the ratio of the hydraulic diameter at the flame end of the precombustor to the hydraulic diameter of the fuel nozzle is from about 6 to about 10.
7. The oxy-fuel burner of claim 6 , wherein the precombustor has a divergent geometry and the ratio of the hydraulic diameter at the flame end of the precombustor to the hydraulic diameter of the fuel nozzle is from about 6 to about 8.
8. The oxy-fuel burner of claim 1 , further comprising a staging oxidant nozzle spaced apart from and generally parallel to the primary oxidant conduit.
9. The oxy-fuel burner of claim 1 , further comprising boundary layer disruptors positioned along at least a portion of a wall of at least one of the fuel nozzle and the primary oxidant nozzle.
10. The oxy-fuel burner of claim 9 , wherein the boundary layer disruptors are selected from the group consisting of: dimples, indentations, bumps, scribes, grooves, channels, mesh, and combinations thereof.
11. The oxy-fuel burner of claim 9 , wherein the boundary layer disruptors are positioned along at least a portion of the inner wall of the primary oxidant nozzle and are configured so as to increase the turbulence of oxidant flowing in the primary oxidant passage.
12. The oxy-fuel burner of claim 9 , wherein the boundary layer disruptors are positioned along at least a portion of the outer wall of the fuel nozzle and are configured so as to increase the turbulence of oxidant flowing in the primary oxidant passage.
13. The oxy-fuel burner of claim 9 , wherein the boundary layer disruptors are positioned along at least a portion of the inner wall of the fuel nozzle and are configured so as to increase the turbulence of fuel flowing in the fuel passage.