松木片有氧烘焙反应机理与物料、能量平衡研究OA

Using typical forestry waste pine wood chips as raw material,an industrial aerobic roasting experiment was carried out on a self-built 200 kg/h double-drum rotary wall-type roasting test device.The reaction mechanism,ma-terial,and energy balance characteristics under two typical operating conditions were studied and analyzed.The re-sults showed that temperature and residence time are key parameters affecting the roasting depth and product distribu-tion.Under the conditions of test Ⅰ,with a reaction zone temperature of 260-280℃and a residence time of 8 mi-nutes,deep roasting was achieved,with a solid yield of 64%.The obtained biochar was dark black,and the energy density increased by about 19%.In test Ⅱ,due to insufficient temperature(＜220℃)and shorter residence time(7 minutes),the reaction was mainly dehydration and slight pyrolysis;oxidation was weak,and the solid yield was 78%,with limited improvement in biochar quality.Based on the quantitative analysis of the gas-phase product com-position and oxygen consumption,the generation mechanism of CO2 was briefly analyzed.In the deep-roasting test Ⅰ,the contributions of decarboxylation and oxidation reactions to CO2 generation were 75.3%and 24.7%,respectively,indicating that even in the presence of oxygen,pyrolytic decarboxylation remains the main pathway for CO2 produc-tion.In the shallow-roasting test Ⅱ,the decarboxylation contribution was as high as 96.5%,with weak oxidation,and it was speculated that the water-gas shift reaction affected the gas composition under low-temperature catalytic conditions,leading to a high H2/CO ratio.The system energy efficiency of test Ⅰ was 77%,and the energy yield reached 76%,indicating that most of the biomass energy is effectively retained in the solid product.Energy losses mainly came from system heat loss(23%)and chemical energy in the gaseous products(11%).The heat released accounted for about 2%of the total input chemical energy,equivalent to replacing about 13%of external dimethyl e-ther fuel,demonstrating the potential of aerobic roasting to reduce external energy consumption.This study provides a theoretical basis and data support for further process optimization and industrial application of aerobic roasting.