Characterization of fuel oil atomizers at industrial scale

Nowadays heavy fuel oils represent a significant source of energy available for different applications, either for processes or for power generation. The combustion performance for this type of material considering efficiency, pollutant emissions, etc. is very much influenced by the atomization process and by the oxidant used in combustion. Oxy-combustion can provide advantages with heavy fuels oils such as reducing the vaporization time, as well as reducing the environmental impact, improving the operational economy in terms of reduced fuel consumption or increasing the productivity due to more efficient heat transfer particularly for processes such as glass and steel making. This paper reports the methodology and main aspects considered to evaluate and optimize the design of an air assisted atomizer for industrial scale, from the operational conditions set up and spray characterization measurements reliability, to the impact for the particular application on oxy-combustion. To carry out the study, the available facilities have fundamental impact on the results; therefore particular emphasis is dedicated to work at optimized conditions. A description of the atomization bench, associated diagnostics and furnace is made as well as an analysis of their reliability in such environment. The results show the spray characteristics and dimensionless SMD for various operating conditions and for two atomizer designs. Corresponding flame characteristics are also reported as well as thermal efficiency and NOx emissions. In general, the methodology used allowed to optimize the atomizer design, with a reduction by 3 times of the atomizing air flow rate for the same droplet size. This optimization has resulted in a significant improvement of the furnace thermal efficiency and in an important reduction of NOx emission by 20%, proving the reliability of heavy fuel oil spray characterization at industrial scale.