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过程工程学报 ›› 2016, Vol. 16 ›› Issue (5): 819-826.DOI: 10.12034/j.issn.1009-606X.215414

• 过程与工艺 • 上一篇    下一篇

松木屑水热提质过程及其燃烧特性

李田,赵培涛,祝飞   

  1. 中国矿业大学 电力工程学院
  • 收稿日期:2015-12-16 修回日期:2016-04-20 出版日期:2016-10-20 发布日期:2016-10-14
  • 通讯作者: 赵培涛

Hydrothermal Upgrading and Combustion Characteristics of Pine Sawdust

LI Tian ,ZHAO Pei-tao ,ZHU Fei   

  1. School of Electric Power Engineering, China University of Mining and Technology
  • Received:2015-12-16 Revised:2016-04-20 Online:2016-10-20 Published:2016-10-14
  • Contact: ZHAO Pei-tao

摘要: 以松木屑为原料,采用高压反应釜,在高压、液固质量比12:1、搅拌转速150 r/min、反应时间1 h的条件下,在220?260℃温度范围内进行水热提质实验,对产物进行分析,研究温度对燃料特性、燃料性能及动力学特性的影响. 结果表明,松木屑的碳含量和热值随水热提质温度升高逐渐增大,260℃时含碳量由48.10%增加到69.05%,热值由19.12 MJ/kg增加到26.66 MJ/kg. 松木屑的热值增长趋势与其它生物质相同,但增长幅度异于其它生物质. 水热提质过程中,木屑各组分发生脱羧、脱水、聚合、芳香化等反应,大分子物质分解成小分子物质如气体和有机酸等. 水热提质有助于改善着火性能,随水热温度提高,最大燃烧速率对应的温度降低,燃烧时间延长. 原木屑的燃烧反应为二级反应,水热提质后燃烧反应为一级反应,且活化能显著降低,为33.68 kJ/mol. 水热提质可显著提高木屑的能量密度,改善其燃烧性能.

关键词: 生物质, 水热提质, 燃料特性, 热重分析, 活化能

Abstract: Pine sawdust, which was mixed with deionized water at a mass ratio of 1 to 12, was hydrothermally upgraded in an autoclave reactor under a temperature of 220?260oC and a rotating speed of 150 r/min for 1 h. The characteristics of the generated hydrochar were analyzed to investigate the effect of hydrothermal temperature on the fuel properties, combustion characteristics and kinetic parameters. The results show that the carbon content and heating value of the hydrochar were increased with the hydrothermal temperature. At a hydrothermal temperature of 260oC, the carbon content was increased from 48.10% to 69.05% and the heating value was improved from 19.12 MJ/kg to 26.66 MJ/kg. According to the literature, the variation trend was similar to those of other biomass, whereas the rising rate was a little different. Based on the results from the HPLC and GC-MS, the decarboxylation, dehydration, polymerization and aromatization happened simultaneously in the hydrothermal upgrading of pine sawdust. During the hydrothermal upgrading process, the macromolecular substances were decomposed into small molecules including gas products and organic acids because of these reaction. The results from the TG analysis show that the hydrothermal upgrading was beneficial for improving the ignition performance of the pine sawdust. The combustion temperature which presented the maximum combustion rate kept decreasing with the hydrothermal temperature. However, the time needed to burnout all the sample was increased with the hydrothermal temperature. According to the Arrhenius law, the combustion of pine sawdust could be characterized by the second-order reaction, while that of the hydrochar was characterized by the first order reaction with an activation energy of 33.68 kJ/mol. All these results indicate that the hydrothermal upgrading could improve the energy density and combustion performance of pine sawdust.

Key words: biomass, hydrothermal upgrading, fuel properties, thermogravimetric analysis, activation energy