氧和水蒸气浓度及升温速率对生物质燃烧的影响

Effect of oxygen,moisture content and heating rate on biomass combustion

采用热重实验法,实验研究了升温速率、氧浓度和水分浓度对生物质燃烧的影响.研究结果表明,升温速率过大时会发生热滞后现象,着火倾向发生在颗粒表面,对燃烧特征温度、失重速率和剩余质量百分数均有影响;当氧浓度较大时,氧向固体层的质量传递作用加强,使得挥发分与固体层同时发生燃烧,燃烧速率明显增大而燃烬温度降低;水分浓度影响了生物质的燃烧,湿空气燃烧不稳定的原因是水分的凝结与蒸发,湿空气燃烧会造成炉膛热负荷波动.

Effects of heating rate, oxygen concentration and water concentration on biomass combustion were investigated by themogravimetric analyzer. It is found that thermal hysteresis occurs and ignition tends to occur in particle surface when heating rate is too high, and the combustion characteristic temperature, mass loss rate and the percentage of residual mass are all affected. With the increasing of oxygen concentration, mass transfer o{ oxygen to the solid layer is strengthened, making the volatile matters and solid layer burn simultaneously and resulting in a larger burning rate but a lower burnout temperature. Moisture concentration in humid air affects the biomass combustion. The combustion instability is due to condensation and evaporation of water, which cause fluctuation of heat load in the furnace.