Pyrolysis of thermally thick beech wood blocks with a size of around 2.5×8×6 cm^(3)(width×length×height)was carried out in a lab scale microwave reactor with a frequency of 2.45 GHz,operated,both,a...Pyrolysis of thermally thick beech wood blocks with a size of around 2.5×8×6 cm^(3)(width×length×height)was carried out in a lab scale microwave reactor with a frequency of 2.45 GHz,operated,both,at 300 W and 600 W under inert conditions,using N_(2) at around 400 mbar absolute pressure.The microwave cavity had a size of 20×20×20 cm^(3).The specific energy supply referred to the untreated wood block was 4-8 W/g,with slight variations depending on the initial water content.The mass loss and the reflected microwave power were in-situ monitored during the experiments.The sample surface and chamber temperatures were measured with a pyrometer and a thermocouple,respectively.Physico-chemical and dielectric properties of the produced solids were investigated and compared to those of chars produced under conventional pyrolysis using the same raw materials.It is shown that the complex dielectric permittivity of the solid products changed drastically during the pyrolysis process,with increasing heating properties as the conversion process evolved.This was easily achieved using 60o W without susceptors.However,300 W was not enough to achieve a high conversion degree,independently of the irradiation time.This,together with the physico-chemical analyses of the solids,hinted to the importance of the transport kinetics in thermally thick materials,although further investigationis still required.展开更多
基金the funding by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-Project-ID 422037413-TRR 287.
文摘Pyrolysis of thermally thick beech wood blocks with a size of around 2.5×8×6 cm^(3)(width×length×height)was carried out in a lab scale microwave reactor with a frequency of 2.45 GHz,operated,both,at 300 W and 600 W under inert conditions,using N_(2) at around 400 mbar absolute pressure.The microwave cavity had a size of 20×20×20 cm^(3).The specific energy supply referred to the untreated wood block was 4-8 W/g,with slight variations depending on the initial water content.The mass loss and the reflected microwave power were in-situ monitored during the experiments.The sample surface and chamber temperatures were measured with a pyrometer and a thermocouple,respectively.Physico-chemical and dielectric properties of the produced solids were investigated and compared to those of chars produced under conventional pyrolysis using the same raw materials.It is shown that the complex dielectric permittivity of the solid products changed drastically during the pyrolysis process,with increasing heating properties as the conversion process evolved.This was easily achieved using 60o W without susceptors.However,300 W was not enough to achieve a high conversion degree,independently of the irradiation time.This,together with the physico-chemical analyses of the solids,hinted to the importance of the transport kinetics in thermally thick materials,although further investigationis still required.
