Interests in charcoal usage have recently been re-ignited because it is believed that charcoal is a muchbetter fuel than wood. The conventional charcoal production consumes a large amount of energy due to the prolonge...Interests in charcoal usage have recently been re-ignited because it is believed that charcoal is a muchbetter fuel than wood. The conventional charcoal production consumes a large amount of energy due to the prolonged heating time and cooling time which contribute to the process completing in one to several days. Wood py-rolysis consists of both endothermic and exothermic reactions as well as the decomposition of the different components at different temperature range （hemicellulose： 200-260℃; cellulose： 240-350℃ and lignin： 280-500℃）. Inthis study we propose a multistagepyrolysis which is an approach to carry out pyrolysis with multiple heating stages so as to gain certain processing benefits. We propose a three-stage approach which includes rapid stepwise heating stage to a variable target temperatures of 250 ℃, 300℃, 350 ℃ and 400 ℃, slow and gradual heatingstage to a tinal temperature of 400℃ and adiabatic with cooling stage. The multi-stage pyrolysis process can save 30% energy and the processing time by using a first temperature target of 300 ℃and heating rate of 5℃.min-1 to produce a fixed-carbon yield of 25.73% as opposed to the base case with a fixed-carbon yield of23.18%.展开更多
基金Supported by the Hong Kong RGC in form of PhD Fellowship to Adetoyese Olajire Oyedun(PF09-05997)
文摘Interests in charcoal usage have recently been re-ignited because it is believed that charcoal is a muchbetter fuel than wood. The conventional charcoal production consumes a large amount of energy due to the prolonged heating time and cooling time which contribute to the process completing in one to several days. Wood py-rolysis consists of both endothermic and exothermic reactions as well as the decomposition of the different components at different temperature range （hemicellulose： 200-260℃; cellulose： 240-350℃ and lignin： 280-500℃）. Inthis study we propose a multistagepyrolysis which is an approach to carry out pyrolysis with multiple heating stages so as to gain certain processing benefits. We propose a three-stage approach which includes rapid stepwise heating stage to a variable target temperatures of 250 ℃, 300℃, 350 ℃ and 400 ℃, slow and gradual heatingstage to a tinal temperature of 400℃ and adiabatic with cooling stage. The multi-stage pyrolysis process can save 30% energy and the processing time by using a first temperature target of 300 ℃and heating rate of 5℃.min-1 to produce a fixed-carbon yield of 25.73% as opposed to the base case with a fixed-carbon yield of23.18%.
