The characteristics and emissions of low-pressure densified torrefied elephant dung fuel briquette

Artidtaya Mainkaew (Asian Development College for Community Economy and Technology (adiCET), Chiang Mai Rajabhat University, Khilek, Mae Rim, Chiang Mai 50180)
Sommas Kaewluan (Biofuel and Bioenergy Technology Research and Development Laboratory (BBT R&D), Department of Mechanical Engineering, Faculty of Engineering, Srinakharinwirot University, 63 Rangsit-Nakhonnayok Rd., Ongkharak, Nakhon-Nayok, 26120)
Adisak Pattiya (Biomass Pyrolysis Frontier Research Group, Faculty of Engineering, Mahasarakham University, Kamriang, Kantharawichai, Maha Sarakham 44150)
Surachai Narrat Jansri (Asian Development College for Community Economy and Technology (adiCET), Chiang Mai Rajabhat University, Khilek, Mae Rim, Chiang Mai 50180)

International Journal of Renewable Energy Development
Vol 12, No 4 (2023): July 2023

Elephant dung is the camp's undigested fiber waste. For more effective waste management, the conversion of dung to torrefied solid and the formation of solid torrefied into fuel briquettes, as well as their properties, were investigated. The dung was improved through torrefaction at 280ºC for 150 sec in a pilot-scale reactor with a feeding rate of 600 g/h. The torrefied elephant dung had 17 MJ/kg of HHV, a solid yield of 79%, and a fixed carbon content of 20%. A mixture of torrefied dung, binder, and water was compressed at 40 bars to a density of 860 kg/m3, or 12 GJ/m3. Their H/C and O/C atomic ratios were in the range of typical biomass. However, due to their moisture content of over 7%, the HHV of the fuel briquettes was below 17 MJ/kg. Moreover, their thermal efficiency was less than 7% due to durability issues, despite having a great fuel ratio and thermal stability. The combustion of these briquettes resulted in less than 850 ppm of CO. To improve the combustibility of this solid biofuel, it is recommended to develop a production process and a suitable stove specifically for these briquettes.