Micro-explosion of emulsified fuel droplet and its combustion characteristics in a boiler

An experimental system for observing the drop vaporization and micro-explosion characteristics of emulsified droplets in high-temperature environments was conducted to analyze the effects of environmental temperature, droplet size, and water content on droplet behavior. In addition, emulsified low-sulfur heavy fuel oil (HFO) with a 20 vol% water content and pure low-sulfur HFO were used as fuels for burning in an industrial boiler under normal operating conditions. The results showed that by using an emulsified HFO with a 20 vol% water content, the boiler efficiency can be improved by 2%, and that a reduction of 35 ppm in NOx emissions (corresponding to a NOx reduction rate of 18%) can be achieved. These advantages are due to the occurrence of a micro-explosion during the combustion of the emulsified droplets. It was observed that when emulsified HFO with a 20 vol% water content was used, the fuel (HFO) consumption rate was 252 L/h. On the other hand, the fuel consumption rate was 271 L/h when pure low-sulfur HFO was used. Therefore, a reduction of 19 L/h in the fuel (HFO) consumption rate was achieved when using the water-in-oil emulsion, corresponding to a 7% increment in energy savings (fuel savings).