Water-In-Oil Emulsion as Boiler Fuel for Reduced NOx Emissions and Improved Energy Saving

Abstract

An experimental system for observing the drop vaporization and microexplosion 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 microexplosion 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 fuel savings of 7%.