Performance of Flammability and NO-x Emission in Premixed Oil Burner Ulterasonic Atomization

摘要

In the combustion of low vapor pressure liquid fuel, it is necessary for instantaneous ignition to preheat the liquid fuel evaporaor at any required time. For example, in the kerosene vaporizing type boiler for home use, electric power is consumed in the preheating kerosene vaporization to supply hot water, even on standby. To avoid the preheating process by electric power during the sandby period, the technology that can vaporize liquid fuel instantaneousy needs to be developed. From this viewpoint, the applcation of the ultrasonic atomization was proposed to ignite liquid fuel without any heating process. Similar trials had already been done but no stabilized conbustion was accomplished by ultrasonic atomizing, using an MHz frequency. In this work, a kerosene pre-mixed burner equipped with a 1.7-MHz ultrasonic oscillator was manufactured and the characteristics of atomization ofkerosene, stable combustion region and NO_x wmis-sion on this ultrasonic atomization burner are examined. The relatively quick ignition with a few seconds delay was realized. The atomization ofKerosene was obtained at the rate of 0.75 g/min, which is proportional to the time and the average kerosene droplet size, 3.1 muM, produced by 1.7 MHz ultrasonic oscillation. 0.54 kW load was obtained by using this combustor. Stable combustion was obtained around 0.7 in the equivalence ratio. The stable combustion was defined as [CO]/[CO_2]< 0.002 forcombustion exhaust gas.23 ppm of low NO_x emission (O_20% base) is accomplished in the stable combustion region as it can provide the balance between both primary and secondary air flow rates.