Abstract: A combustion process in which a water-in-oil emulsion of liquid fuel, such as liquid hydrocarbons, containing from 10 to 50% water and preferably 10 to 30% water is burned. The emulsion is produced, with little or no added emulsifying agent, by sonic agitation, including a sonic generator and an acoustic transformer having a larger cross-section coupled to or in contact with the sonic generator than at its other end, at which emulsification takes place, whereby the sonic energy density is increased. With the increased sonic density an emulsion is produced which when burned produces a quality of burn such that the combustion is faster, more complete, and cleaner, with an increase in efficiency even up to 30% of water. The increase in efficiency often equals that obtained by the burning of the same weight of pure fuel in the conventional manner.

Abstract: Pulverized coal is slurried with water then oil or if desired oil and pulverized alkalis preferably lime or limestone is added and the mixture subjected to sonic vibrations with an energy density of at least 11.625 watts per cm.sup.2. Liquid suspension is produced and any excess water or oil separates out as a separate phase. Normally excess oil is used and the excess oil phase can be recycled. The resulting dispersion is utilized and burned in a furnace. A clean flame is produced which has the characteristics of an oil flame and not a powdered coal flame. The addition of lime is optional as its purpose is to reduce sulfur dioxide in burning where the coal contains sulfur. If there is no sulfur or so little as to meet environmental standards the addition of lime may be omitted. The amount of lime is preferably at least about twice stoichiometric based on the sulfur content of the coal.