不同结构烟草纤维素的燃烧热解特性

摘要

In order to study the combustion and pyrolysis characteristics of tobacco celluloses with different structures, the celluloses were extracted from flue-cured tobacco, burley tobacco, oriental tobacco and tobacco stem, and their crystal structures were characterized. The combustion behavior and pyrolysis process of different types of tobacco celluloses were comparatively studied with thermogravimetric (TG) analyser and micro combustion calorimeter (MCC). The composition of pyrolysis products and the releasing behaviors of carbonyl compounds were measured by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and an off-line pyrolysis furnace. The results showed that: 1) The cellulose structure of the different types of tobacco differed significantly, the cellulose of oriental tobacco had higher crystallinity, secondary fiber content, larger accessible fibril surface and fibril size. 2) The flammability of oriental tobacco cellulose was poor, its thermal stability was the worst at low temperatures (<350 ℃), however its carbon residue was the highest at high temperatures. 3) Tobacco stem cellulose produced more small molecular compounds, and the release of carbonyl compounds from oriental tobacco cellulose was slightly different with the other three tobacco celluloses. The structure differences of tobacco celluloses resulted in different combustion and pyrolysis characteristics.%为研究不同结构烟草纤维素的燃烧热解特性,分别从烤烟、白肋烟、香料烟和烟梗中提取了具有不同结构特征的烟草纤维素,并对其结晶进行了结构表征;采用热重(TG)分析法和微燃烧量热(MCC)法比较研究了不同类型烟草纤维素的热解过程和燃烧特征;利用热裂解-气相色谱/质谱联用(Py-GC/MS)法和管式炉离线热解装置分别探讨其热解产物组成及羰基化合物的释放规律.结果发现:①不同类型烟草纤维素的结构存在明显差异,其中香料烟纤维素具有较高的结晶度、次晶纤维量,以及较大的可及基原纤表面和基原纤尺寸.②香料烟纤维素的燃烧性较差,其在低温阶段(<350℃)的热稳定性最差,但在高温阶段却具有最高的残炭量.③烟梗纤维素热解产生了更多的小分子化合物,香料烟纤维素羰基化合物的释放规律与其他3种烟草纤维素略有不同.烟草纤维素结构上的差异,使其相应表现出了不同的燃烧热解特性.