Comparison of the physical properties of cotton and sesame stalk pellets produced at different moisture contents and combustion of the finest pellets

In this study, cotton and sesame stalks that are grown regionally and burned in coarse form as a source of heat energy form in the current application are used as pellet raw materials. Although these residues are used as biomass raw materials in different forms, there is limited information about their use as pellets. In order to compare the production efficiency and physical properties of the pellets obtained, production capacity, specific energy consumption, bulk density, particle density, durability, compression resistance, specific compression resistance, and tensile strength tests have been applied. In the moisture content ranges pellet durability, bulk density, particle density and tensile strength were achieved as 89-98%, 430-695 kg/m3, 921-1367 kg/m3, 2.83-7.28 Mpa for cotton stalk pellets, and 93-97%, 510-660 kg/m3, 4.26-5.85 Mpa for sesame stalk pellets, respectively. 20% pelletizing moisture for both stalks increased pellet production capacity, reduced energy consumption, but affected negatively their physical structures. It was concluded that the ideal pelleting moisture values for cotton stalks and sesame stalks were 10% and 15%, respectively. During combustion experiments, O2, CO2, CO, and NOx emissions, flue gas temperature, and combustion efficiency were observed. According to the results of combustion experiments, CO and NOx emissions were found to be 1646 ppm and 50 ppm for cotton stalks, 2862 ppm and 134 ppm for sesame stalks, respectively. High O2 emission values (18-19%) were observed for both pellets.