Glycerol combustion and emissions

With the growing capacity in biodiesel production and the resulting glut of glycerol, the largest by-product of the transesterification process, there is interest in finding alternative uses for this glycerol. One option is to burn it locally in a boiler for combined process heat and power. Due to its low energy density, very high viscosity, and high auto-ignition temperature, glycerol is not easy to burn. Additionally, the composition can change dramatically depending upon the biodiesel feedstock (e.g. soy oil or rendered chicken fat), the catalyst used, and the degree of post reaction cleanup. Using a high-swirl burner, we report a wide range of emissions measurements, including aldehydes and NOx, and compare a number of different grades of glycerols between themselves as well as with diesel fuel and propane. Measurements indicate that a properly designed burner can safely combust glycerol.