“双碳”背景下市政绿化生物质烘焙热解转化实验研究

Experimental research on torrefaction and pyrolysis conversion of municipal greening biomass under the background of “Dual Carbon” policy

中文关键词: 节能减碳  市政绿化生物质  酸洗-烘焙  热解特性  动力学机理

英文关键词: Energy conservation and carbon reduction  Municipal green biomass  Acid washing- torrefaction  Pyroly-sis characteristics  Kinetics mechanism

中文摘要:

      在“3060”战略目标指引下，节能减碳行动已经渗透到各行各业，市政绿化生物质是十分重要的可再生碳基能源，可作为替代燃料达到节能减碳的效果。本文以市政绿化生物质——法国梧桐树叶为原料，开展了酸洗-烘焙联合预处理对化学组成、烘焙质量与能量得率、微观结构、产物分布等理化性质及热解特性的影响分析。预处理实验结果表明，酸洗能够减少试样中灰分与S含量，酸洗后烘焙试样中C、H含量随温度的升高而增大，O含量减小，降低了H/C和O/C。联合预处理会破坏纤维素结晶区，使得试样结晶系数逐渐降低。采用热重分析仪研究酸洗-烘焙预处理对热解特性与动力学机理的影响，发现会延缓热解反应的发生，半纤维素失重速率减小，而纤维素与木质素失重速率峰值由PL的6.87、2.73 wt. %/min分别增大至TSPL300的8.32、4.44 wt. %/min。酸洗-烘焙预处理不会改变试样各热解阶段的动力学方程，但会使半纤维素、纤维素、木质素热解活化能增大，而无机矿物质分解活化能降低。水平管式炉实验表明，随着预处理温度的升高，酸洗后烘焙试样热解气中CO含量先升高后降低，CO2逐渐降低，而H2、CH4则小幅上升。XRD结果显示热解残渣的主要成分为Ca(OH)2、C和CaCO3。本研究以期揭示酸洗-烘焙预处理对市政绿化生物质热解过程的影响规律，为其在节能减碳领域的高效利用提供科学指导。

英文摘要:

      Under the guidance of the "3060" strategic goal, energy-saving and carbon reduction actions have pene-trated into various industries, and municipal green biomass, as an important renewable carbon based ener-gy, can be used as an alternative fuel to achieve energy-saving and carbon reduction effects. The paper has selected the Platanus Orientalis L. leaves as the raw material to study effects of acid washing and torrefac-tion on the physi-cochemical properties of chemical compositions, torrefaction mass and energy yields, microstructure, as well as their pyrolysis characteristics. The acid washing and torrefaction results showed that, the contents of ash and sulfur in the sample reduced after the acid washing pretreatment, and the con-tents of carbon and hydrogen in the samples from the combined pretreatments of acid washing and torre-faction would increase with the temperature growing, but reduced oxygen content, and mass ratios of H/C and O/C. The combined pretreatments would destroy the crystallization zone of cellulose, and decrease crystallization coefficients of samples. The thermogravimetric analyzer was employed to study the effects of combined pretreatments of acid washing and torrefaction on the pyrolysis characteristics and kinetic mechanisms. It was found that the pyrolysis reactions would delay, and the weight loss rate of hemicellu-lose decreased, while the maximum weight loss rates of cellulose and lignin respectively increased from 6.87 and 2.73 wt. %/min for PL to 8.32 and 4.44 wt. %/min for TSPL300. The acid washing and torrefac-tion cannot change the kinetic equations of various pyrolysis stages, but can make an increase of activation energies for the pyrolysis of hemicellulose, cellulose and lignin, but decreased the values for the decompo-sition of inorganic minerals. The horizontal tube furnace tests showed that, with the temperature growing, the CO content from the pyrolysis of samples from the acid washing and torrefaction would increase first and then decrease, the CO2 content gradually decreased, while the contents of H2 and CH4 increased slight-ly. The XRD analysis results indicated that the main components in the pyrolysis residues were Ca(OH)2, C, and CaCO3. This study aims to reveal the impact of acid washing baking pretreatment on the pyrolysis process of municipal green biomass, and provide scientific guidance for the efficient utilization of biomass energy in the field of energy conservation and carbon reduction.