华南十种桉树的热值与灰分含量比较

桉树是林业生物质能源的原料之一,了解桉树的热值和灰分含量能为合理利用桉树能源林提供理论参考。该研究采用热量计和马福炉对华南尾巨桉等10种桉树的不同器官进行热值和灰分含量测定。结果表明：10种桉树树叶、树枝、树根、树干和树皮的干质量热值、去灰分热值分别为15.10~21.06 kJ.g-1和16.50~22.11 kJ.g-1,器官的平均干质量热值、去灰分热值以树叶最高(19.50和20.56 kJ.g-1)、树皮的最低(17.32和18.09 kJ.g-1),说明树叶所含的高能有机物质比其它器官多；不同器官的干质量热值与去灰分热值在不同品种中的大小排序不完全一致。灰分含量在0.14％~8.5％之间,器官平均的灰分含量以树叶最高(5.13％)、树干最低(0.30％),说明树叶所含的矿质元素较多。不同器官的热值与灰分含量均差异显著(P<0.05)。植株个体的干质量热值与去灰分热值均以尾叶桉最高(18.99和19.18 kJ.g-1),以托里桉最低(17.53和17.86 kJ.g-1)；灰分含量则以托里桉最高(1.90％)、巨桉最低(0.61％)。相关分析结果表明,灰分含量与干质量热值、去灰分热值存在一定的负相关,但未达显著水平；干质量热值与去灰分热值呈极显著的正相关关系(P<0.01)。由于理想的植物燃料应具备热值高与灰分含量低的特点,结合该研究的结果分析,托里桉作为燃料资源利用不理想,以尾叶桉较为适宜。

Comparison of calorific values and ash contents of ten Eucalyptus species in South China

Eucalyptus is one of the raw materials for forest bio-energy industry. Calorific value and ash content were two important indices for rational use of bio-energy Eucalyptus forest. Calorific values and ash contents of leaves, branches, roots, stem-wood and bark of 10 Eucalyptus species including Eucalyptus urophylla &#215; E. grandis in South China were determined by using calorimeter and muffle furnace. The results showed that gross calorific values(GCV)and ash free calorific values(AFCV)of different organs ranged from 15.10 to 21.06 kJ·g^-1 and 16.05 to 22.11 kJ·g^-1 respectively, leaves had the highest mean GCV and AFCV(19.50 kJ·g^-1and 20.56 kJ·g^-1)and bark the lowest(17.32 and 18.09 kJ·g^-1), which indicated that leaf had higher organic matters than other organs. The orders of decreasing GCV and AFCV of 5 organs in 10 Eucalyptus species werEucalyptus, calorific value, ash content, bio-energy, South Chinae not exactly the same. The ash contents of different organs ranged from 0.14% to 8.5% with leaves having the highest mean value(5.13%)and stem-wood the lowest(0.30%),which indicated that leaf had more mineral elements than other organs. There were significant differences in calorific values and ash contents of 5 organs(P<0.05). As to the whole tree, E. urophylla had the highest GCV and AFCV(18.99 and 19.18 kJ·g^-1), while Corymbia torelliana had the lowest GCV and AFCV(17.53 and 17.86 kJ·g^-1); C. torelliana had the highest ash contents(1.9%)and Eucalyptus grandis the lowest(0.61%). The results of correlation analyses showed that ash content had negative correlation with GCV and AFCV,which was not significant; GCV and AFCV had significantly positive correlation(P<0.01). For ideal plant fuel should have the characteristics of high calorific value and low ash content, of 10 species, Corymbia torelliana had low calorific values and high ash contents, which indicated that it was not ideal fuel species while Eucalyptus urophylla was the optimal species.