Pyrolysis of cherry stones:: energy uses of the different fractions and kinetic study

Cherry stones were pyrolysed in a nitrogen atmosphere. The compositions and properties of the gases, liquids, and solids generated were determined over a range of temperatures (300-800 degreesC) and heating rates (5-20 K min(-1)). Char yields fell and gas yields rose with increasing temperature. The oil fraction yield passed through a maximum at 400-500 degreesC. The decline at higher temperatures was likely due to strong cracking increasing the gas yield. Increasing the heating rate led to a decrease of the char and oil yields and an increase of gas yield. Production varied in the ranges 20-56.8% char, 32-58% oil, and 8.8-47.6% gas, with a mean heating value of 31.8 MJ kg(-1), 11.5 MJ kg(-1) and 15,7 MJ N-1 m(-3), respectively. The char had a high fixed carbon content ( > 76%) as well as the high heating value, and hence could be used as solid fuel, as precursor in activated carbon manufacture, or to manufacture category-A briquettes. Aliphatic and aromatic hydrocarbons and hydroxyl and carbonyl compounds were the major components of the oil, which therefore can be used as liquid fuel or. better, as a source of liquid hydrocarbons. The gas composition was identified as hydrogen, carbon monoxide, methane, carbon dioxide with traces of ethylene and ethane, and can be used to heat the pyrolysis reactor or to generate heat/electricity in a gas-turbine/ vapour-turbine combined cycle, The activation energy of the gas formation was determined to be 92.5, 42.8, 58.1, and 21.9 kJmol(-1) for hydrogen, carbon monoxide, methane and carbon dioxide, respectively. We studied the kinetics of the thermal decomposition of the feedstock using isothermal and non-isothermal thermogravimetric methods at different temperatures (300-600degreesC) and heating rates (5-25 K min(-1)). The results indicated that the isothermal pyrolysis process consisted of two stages and the non-isothermal three stages.