Abstract
Water/heavy oil emulsion prepared by an edge-tone resonant homogenizer without a surfactant is investigated. The three aims of this study are: (1) the spectrum analysis of pressure vibration inside the resonant chamber of the homogenizer, (2) the production of droplets with the desired mean size and a suitable distribution, and (3) the determination of the boiler efficiency using a thermal input-output method. The homogenizer is designed to generate resonant vibrations through the interaction between the jet exit and a knife-like blade under the conditions of high temperature and pressure. The desired mean droplet size (on the order of micrometers) and the proper size distribution for the water/heavy oil emulsion are achieved using the homogenizer. It is found that the amplitude of pressure fluctuation is at its maximum at the first-stage resonant frequency. The boiler efficiency calculated using the thermal input-output method shows that the water/heavy oil emulsion has the potential to reduce energy consumption by 15% compared to that obtained with pure heavy oil. The NO x emissions in the boiler furnace increase with increasing amount of excess air. Additionally, lower CO emissions are found for the boiler firing water/heavy oil emulsions because of the occurrence of micro-explosion, also known as secondary atomization. © 2013 Elsevier Ltd. All rights reserved.