EMISSIVITY AND TURN-DOWN RATIO

FURNACES DESIGNED TO OPERATE ON LIQUID FUELS HAVE RADIATION AS THE MAIN MODE OF HEAT TRANSFER, THEY ALSO HAVE LIMITED TURN-DOWN RATIOS. FLAME EMISSIVITIES FOR OIL AND NATURAL GAS IN INDUSTRIAL APPLICATIONS HAVE BEEN MEASURED AS 0.55 AND 0.15 RESPECTIVELY. THEREFORE, DUE TO THE NATURALLY LOW EMISSIVITY OF THE METHANE FLAME, CONVERSION TO NATURAL GAS (OF FURNACES ORIGINALLY DESIGNED FOR FUEL-OILS OR PULVERIZED COAL) RESULTS IN A WASTE OF FUEL ENTHALPY AND CORRESPONDING LOSS OF THERMAL EFFICIENCY. THIS PROPOSAL IS FOR FUNDS TO INVESTIGATE A NOVEL PLASMA-BURNER CONCEPT. THE CONCEPT IS THAT OF COMBINING A LOW POWER PLASMA JET WITH A NATURAL GAS FUEL FEEDSTOCK. THIS IS DONE IN SUCH A WAY THAT LESS THAN 1% OF THE METHANE THROUGHPUT IS PASSED IN CONTACT WITH THE PLASMA ARC. THE FRACTION THAT ENCOUNTERS THE PLASMA IS COMPLETELY DISSOCIATED TO CARBON AND HYDROGEN. THE NET RESULT IS TO PRODUCE A FLAME SEEDED WITH SMALL CARBON PARTICLE "RADIATORS" TO INCREASE FLAME EMISSIVITY ALONG THE LENGTH OF THE FLAME. THESE PARTICLES WILL BE GENERATED SUFFICIENTLY SMALL TO ENSURE THEIR CONSUMPTION BEFORE LEAVING THE COMBUSTION CHAMBER. THE HYDROGEN ATOMS GENERATED MAY ANCHOR THE FLAME TO THE BURNER AND THUS INCREASE THE EFFECTIVE TURN-DOWN RATIO.