A process model is developed to simulate the performance of a biomass torrefaction unit, which consists of a dryer, a torrefaction reactor, a combustor, and two heat exchangers. The model is capable of predicting the composition of volatiles and torrefied biomass, mass and energy yields, thermal efficiency, process heat requirement, and CO₂ emissions. Useful correlations are presented for the heating value, molecular weight, and specific heat of the volatiles. A comparison of the model prediction with the experimental data reported in the literature shows a very good agreement. The performance of a torrefaction unit with production capacity of 150 MW_th is predicted with an acceptable accuracy using the presented process model. The effect of moisture content, torrefaction temperature, residence time, and adiabatic flame temperature on key process parameters are examined. The thermal efficiency of willow torrefaction unit is found to be 88% at a moisture content of 50% (dry basis), which increases to 94% as the moisture content drops to 20%. The results show that the carbon dioxide produced in the process is notably affected by the torrefaction temperature and the moisture content. A higher moisture content or torrefaction temperature may lead to a higher CO₂ emission. Furthermore, the conditions at autothermal operation are identified and discussed.

中文翻译：

---

生物质烘焙设备的过程建模

开发了一个过程模型来模拟生物质焙烧装置的性能，该装置由干燥机，焙烧反应器，燃烧室和两个热交换器组成。该模型能够预测挥发物和烘焙过的生物质的成分，质量和能量产量，热效率，过程热量需求和CO ₂排放量。提出了有用的相关性，用于挥发物的热值，分子量和比热。模型预测与文献报道的实验数据的比较显示出很好的一致性。烘焙单元与150兆瓦的生产能力性能_个使用所提供的过程模型，可以以可接受的精度预测排放量。研究了水分含量，焙干温度，停留时间和绝热火焰温度对关键工艺参数的影响。发现水分含量为50％（干基）时，柳树烘烤单元的热效率为88％，当水分含量降至20％时，热效率提高至94％。结果表明，该过程中产生的二氧化碳明显受焙干温度和水分含量的影响。较高的水分含量或烘焙温度可能导致较高的CO ₂排放。此外，确定并讨论了自热运行时的条件。