PULSATED O2/FUEL FLAME AS A NEW TECHNIQUE FOR LOW NO(X) EMISSION

A new primary NO(x) reduction method is described. It consists in pulsating one or both fluids from a oxy-gas burner by rotary-plug valve or solenoid electrovalve. The parameters to be set are C the constant fraction of the pulsated gas flow-rate, P the amplitude of the pulsated fraction of the gas flow-rate, O the duration of the maximum flow-rate, F the duration of the minimum flow-rate and phi the dephasing between the two pulsations when both gases are pulsated. Experiments on 20 kW and 50 kW pilot furnaces have shown that up to 90% NO(x) reduction can be achieved without lowering heat transfer when parameters are set as follows (both gases are pulsated): dephasing equal to 1/2, C/P around 0.2 and frequency (1/F+O)) as low as possible. Further developments are underway to perform test on a 1 MW pilot furnace before industrial trials.