烘焙生物质快速热解过程中成焦特性和微观机理研究

Torrefaction is one of the best pretreatment technologies for large-scale and high-value utilization of biomass fuel. Preliminary study showed that torrefaction had a great impact on the absolute char yield and char reactivity after high-temperature pyrolysis, endangering the subsequent thermochemistry utilizations. However, study related to the effects of torrefaction on the char characteristic during fast pyrolysis and its mechanism is few if not absent. This proposal utilize the typical biomass species, isolating the representative major components and controlling the concentrations of the inorganic constituents, systematically investigate the char characteristic and microscopic mechanism. The scopes include: investigating the effects of the biomass major component, inorganic constituents, torrefaction severity and pyrolysis conditions on the char yield and char reactivity, relating which to the transformation of the physicochemical characteristics of the char at different pyrolysis resident time; revealing the microscopic mechanism and reaction path of the torrefaction playing on the char characteristic; building up a multi-component pseudo-mechanistic model which can predict the effects of the torrefaction severity, the concentrations of the inorganic constituents on the char formation of the three major components of biomass under different pyrolysis condition; The result of this proposal can provide experimental data and theoretical guidance to the development and industrial application of the high-temperature chemical conversion of torrefied biomass.

烘焙是最佳的生物质燃料高值化预处理技术之一。初步研究表明烘焙对生物质高温热解的绝对焦产率和焦反应活性有很大的影响，直接影响到后续的热化学转化利用，而对烘焙生物质快速热解过程中成焦特性和烘焙作用机理的研究非常缺乏。项目针对典型的生物质原料，分离有代表性的有机组分和控制典型无机成分的浓度，系统开展生物质烘焙-热解过程成焦特性实验和微观机理研究，掌握烘焙热处理和无机成分对生物质各有机组分在不同热解过程焦产率和焦反应活性的作用规律；同时查明烘焙生物质快速热解过程中热解焦的物理/化学结构的演化规律，揭示烘焙预处理对热解成焦特性作用的微观本质和途径；最后构建能反映烘焙程度和无机成分对焦产率影响的生物质多组分热解反应准机理模型，预测生物质在不同的烘焙-热解条件下的焦产率，为指导烘焙工艺的优化以及烘焙生物质进一步高温热转化利用技术的发展提供实验和理论基础。

烘焙是最佳的生物质燃料高值化预处理技术之一，由于烘焙对生物质高温热解的绝对焦产率和焦反应活性有很大的影响，直接影响到后续的热化学转化利用，因此对烘焙生物质快速热解过程中成焦特性和烘焙作用机理的研究十分重要。本研究通过对生物质及其从主要组分（纤维素、半纤维素和木质素）进行实验研究，掌握烘焙预处理对生物质热解过程焦产率、焦反应性和焦物理化学结构等特性的作用规律；在此基础上，探明烘焙生物质及其热解焦的理化结构演化特性，从微观层面揭示烘焙生物质的热解焦形成路径和烘焙预处理对热解成焦特性的作用机制。并基于在高温、高升温速率下开展的烘焙生物质颗粒燃烧实验，建立了烘焙质量得率与焦产率间的关联模型、详细的脱挥发分（热解）模型、详细的焦转化分段模型；基于所建立的三个模型，分别能够实现对烘焙生物质热解焦产率的预测、对高温脱挥发分时间的预测以及对焦转化的总时间和颗粒收缩规律的预测。此外，本项目还构建45种南方典型木质生物质的燃料特性库，并通过实验获得了原木颗粒以及水洗、烘焙后木颗粒的高温焦燃烧特性及焦产率，以及TGA热重转化数据和燃烧、气化反应动力学参数。本项目为烘焙生物质的热解、燃烧/气化提供了一定的理论基础。