生物质醇解重质油的表征及燃烧特性研究

Characterization and combustion kinetics analysis of fuel oil derived from biomass liquefaction with 1-octanol

对木质生物质醇液化产物重质油进行了理化性质表征、元素分析、热值测定、分子量分布研究及红外光谱分析。结果表明,醇解重质油主要来源于生物质中木质素的降解,是含有羟基、甲氧基、羰基、醚键等多种含氧官能团的芳烃或酚类化合物。重质油常温下是沥青状粘稠固体,其峰位分子量包括2 805和242两个部分。重质油的热值为36MJ/kg,是快速热解油的2倍。此外,重质油中氧、氮、硫总杂原子含量远低于快速热解油品,而且重质油含水率低,酸值远小于快速热解油,因而更利于作为燃料使用。而对重质油的热重分析结果表明,重质油燃烧过程基本可以分为4个阶段,依次为重质油中小分子组分的挥发(室温～130℃),易挥发物组分的着火燃烧(130～300℃)、难挥发的大分子物质的逸出燃烧(300～490℃)以及固定碳的燃烧(490～690℃)。其中,第二阶段的易挥发物组分质量占重质油总质量的30%左右,而第三阶段的难挥发组分质量占重质油总质量的25%。重质油燃烧过程的动力学研究表明,重质油中易挥发物组分的着火燃烧、难挥发的大分子物质的逸出燃烧以及固定碳的燃烧这三个阶段都符合一级反应过程,其燃烧活化能依次为22.76～28.58kJ/mol,3.838～6.457kJ/mol及17.995～36.128kJ/mol。

This paper focuses on the analysis of heavy oil derived from biomass liquefaction.Through FTIR,molecular weight distribution,ultimate and heating value analysis,it is shown that heavy oil is mainly the degradation of lignin in biomass and comprises aromatic or phenolic compounds containing hydroxyl,carbonyl,ether and other oxygen-containing functional groups.Heavy oil is asphalt-like and sticky solid,and its peak molecular weight contains two parts,2805 and 242.The heating value of heavy oil is 36 MJ/kg that is two times of fast pyrolysis oil.Moreover,heavy oil has low water content and its acidity is much less than fast pyrolysis oil,so heavy oil is much better for fuel.The TG analysis shows that the whole process can be divided into four phases： the evaporation of small molecular fraction（room temperature ~ 130 ℃）;the combustion of volatile fraction（130 ~ 300 ℃）;the escaping and combustion of nonvolatile fraction（300 ~ 490 ℃）;the combustion of fixed carbon（490 ~ 690 ℃）.In the second phase,the volatile fraction accounts for around 30% of the total amount of heavy oil.And in the third phase nonvolatile fraction is nearly 25%.The kinetic analysis indicats that the three phases of combustion process can be described as three consecutive first order reactions.And the activation energy of these three phases are 22.76~28.58 kJ/mol,3.838~6.457 kJ/mol and 17.995~36.128 kJ/mol respectively.