热解过程中生物质半焦比热容的测定

采用热重-差示量热扫描法(TG-DSC)测量了生物质和一次热解焦炭及不同转化率下半焦的比热容,建立了计算半焦比热容的数学模型并与实验测量结果进行了对比。结果表明,生物质样品和热解焦炭的比热容在60~200℃随温度升高而线性增大。生物质焦炭的比热容低于生物质样品的比热容,从60℃时的1.2 J/(g·K)增大到200℃附近的1.8~2.0 J/(g·K)。生物质半焦比热容随热解转化率的提高而降低。由半焦比热容数学模型计算得到的结果在接近150~200℃时与实验测定的半焦比热容数值基本一致。

Determination of specific heat capacity of biomass char during pyrolysis

The specific heat capacities of chars during primary pyrolysis of biomass with different conversion and the heat capacities of virgin biomass were determined. The ratio method was employed to measure the specific heat capacities of two biomass samples and their pyrolyzed chars through thermogravimetry and differential scanning calorimetry (TG-DSC). A mathematical model was developed to calculate values of specific heat of chars. The results show that the specific heat capacities of the two biomass samples and their derived chars increase linearly within 60~200℃. The values of the specific heat capacity of the chars are lower than those of the virgin biomass samples. The specific heat of chars decreases as the extent of pyrolysis increases. The calculated specific heat capacities from the developed mathematical model are quite close to those measured by TG-DSC analyses between 150~200℃.