Abstract

Residual biomass is a low-cost raw material, although it must overcome some limitations such as its low calorific value, seasonal availability, and high humidity, which reduces its quality as a fuel. Hydrothermal Carbonization (HTC) is an operation that increases the energy density of raw biomass, obtaining a final solid (hydrochar) with higher calorific value and hydrophobic properties. This work studies the drying process of the hydrochar obtained from Pinus radiata sawdust in an indirect rotary dryer. The process was modeled by the Schlünder and Mollekopf penetration model. The fit obtained with the experimental data indicates an acceptable performance. The mass transfer coefficient varied between 69.4 and 131.7 W/m²·K (average solid temperature) and from 83.9 to 165.8 W/m²·K (100 °C as solid temperature). The mixing number (N_mix) determined was between 19.19 and 24.39, comparable to that reported in the literature. The significant effects on the process were heating steam pressure and the turning speed of the drum. Finally, through a response surface analysis, the optimum nondimensional drying rate value was determined: V_sec = 0.0040 kg _H2O/kg_db ·s.

摘要

残余生物质是一种低成本原材料，但它必须克服一些限制，例如低热值、季节性可用性和高湿度，这会降低其作为燃料的质量。水热碳化 (HTC) 是一种提高生物质能量密度的操作，获得具有更高热值和疏水性的最终固体（水碳）。这项工作研究了在间接旋转干燥机中从辐射松锯末获得的水焦的干燥过程。该过程由 Schlünder 和 Mollekopf 渗透模型建模。用实验数据获得的拟合表明可接受的性能。传质系数在 69.4 到 131.7 W/m ² ·K（平均固体温度）和 83.9 到 165.8 W/m 之间变化² ·K（100 °C 作为固体温度）。确定的混合数 ( N _mix ) 介于 19.19 和 24.39 之间，与文献中报道的相当。对该过程的显着影响是加热蒸汽压力和滚筒的转动速度。最后，通过响应面分析，确定了最佳无量纲干燥速率值：V _sec = 0.0040 kg _H2O /kg _db ·s。