Combustion performance and emissions of petrodiesel and biodiesels based on various vegetable oils in a semi industrial boiler

This paper intends to investigate combustion of petrodiesel and biodiesels of grape seed, corn, sunflower, soybean, olive and rice bran oils, which were produced through an alkali-based transesterification, in a non-pressurized, water-cooled combustion chamber by determining its combustion performance and gas emissions (CO, CO2, NOx, SO2). First, the influence of fuel pressure which related to the rate of sprayed fuel to the chamber was studied in order to find out an optimum combustion pressure. In the next level, the influence of A/F upon emissions and boiler performances at 13.79 bars was studied. Results show that similar combustion of fuels occurred at 13.79 bars (optimum) where due to the increase in fuel pressure, the effect of viscous forces in flame formation disappeared. Complete combustion of fuels occurred at 19.305 bars where the CO emissions of all the fuels reached to zero.The overall performance of the boiler obtained with the methyl esters and petrodiesel are comparable for the defined operating points (especially at high energy rates and low A/F). All the six kinds of vegetable based methyl ester emitted lower emissions than petrodiesel over the wide fuel pressures, and A/F. Meanwhile, biodiesels emitted higher amounts of NOx than petrodiesel. Biodiesels also emitted higher amounts of CO than petrodiesel at low fuel pressures when the viscous forces interfered with proper distributions of fuels to the combustion chamber.

► Investigation of performance and emissions of biodiesel and petrodiesel in a semi industrial boiler.
► Studies were carried out over a wide fuel pressures and air to fuel ratios.
► Biodiesels has a comparable performance with petrodiesel.
► Biodiesel has a significant lower CO2 emission than petrodiesel.
► Biodiesel has a higher NOx emissions than petrodiesel over the whole energy rates and air to fuel ratios.
► Biodiesels make a good substitute of petrodiesel for domestic heating in boilers.