竹炭理化性能的测试和分析

参考相关国家标准,对浙江省18家竹炭厂216组竹片炭的含水率、密度、灰分、挥发分、固定炭含量、燃烧热值、电阻率和pH值等理化性能进行测试.应用Matlab软件,采用概率密度分布方程、主分量分析和方差分析方法对竹炭的理化性能进行分析.结果表明:不同的竹炭生产厂家生产的竹炭理化性能差异极显著,而同一厂家生产的竹炭理化性能差异不显著;竹炭的理化性能相关性不紧密;挥发分和灰分与热值和pH值因子负荷量为异号,呈负相关;固定炭与热值和pH值因子负荷量为同号,呈正相关;灰分和密度与电阻因子负荷量为异号,呈负相关;灰分和密度与电导率因子负荷量为同号,呈正相关.     

植物热值研究综述

植物热值是衡量第一性生产力水平的重要指标。首先,综述了国内外植物热值的研究概况以及所取得的主要成果,包括:植物热值在各群落、科间、种间、无性系、器官等不同层次上的差异,以及凋落物和薪材等热值的研究;热值随季节、年龄和群落演替过程等时间尺度以及经纬度、海拔等空间尺度的变化规律。其次,总结了影响植物热值的因素,包括含碳量、灰分含量以及有机质的含量等内在因素和自然环境、栽种方式、管理措施以及贮藏方式等外在因素。最后,对当前植物热值研究的不足及未来进行了展望与相关讨论。     

早材管孔分布对环孔材栎木蠕变特性的影响

在采用生物图像软件(IPP 6.0)表征环孔材栎木横切面管孔组织比量与分布特性的基础上,探究不同温度条件下早材管孔分布对环孔材栎木板材弯曲蠕变行为的影响,利用Burger模型和五参数模型对其蠕变特性进行模拟预测,为木材弯曲加工成型、木质材料热压成型和木结构设计提供参考。利用动态热机械分析仪测试不同温度条件下环孔材栎木试样(试样A为早材管孔带位于试样中部的木材试样、试样B为对照组-无早材管孔带木材试样)的应变曲线,并采用Burger模型和五参数模型对环孔材栎木蠕变应变曲线进行预测模拟,分析温度作用下早材管孔带对环孔材栎木试样蠕变特性的影响。结果表明:所有试样的应变均随温度的升高而增大,且试样A的应变大于试样B,说明早材管孔带的存在一定程度上增大了环孔材栎木的蠕变应变。此外,在20～50℃温度范围内,试样A相对于试样B的应变增量随着温度的升高而增大;而在50～80℃温度范围内,对应的应变增量随着温度继续升高而减小。Burger模型和五参数模型对于模拟预测环孔材栎木的蠕变行为都具有较好的效果,并且Burger模型拟合的决定系数(R~2)均大于0.96;而由于非线性拟合的引入,五参数模型可以更好地预测模拟环孔材栎木蠕变行为,其R~2均大于0.98。     

抽提处理对尾巨按木材干缩性的影响

为了抑制桉木干缩,采用全因子试验方法研究抽提工艺对尾巨桉木材干缩性的影响.试验结果表明:碱抽提对尾巨桉木材线性干缩率(径向、弦向)、体积干缩率的影响规律不一,但第6、8,9组方案的碱抽提试样的差异干缩率趋近于1;冷水抽提对尾巨桉木材线性干缩率(径向、弦向)、体积干缩率的影响规律比热水抽提明显,热水抽提材的差异干缩波动幅度比冷水抽提材大,效果较好的工艺组合也明显少;第3,4、7、8、11、12组方案的冷水抽提试样的差异干缩趋近于1,而仅第12组方案的热水抽提试样的差异干缩趋近于1.因此,碱抽提和水抽提可以降低尾巨桉木材干缩性的各向异性.     

试样厚度及缺角对人工林木材顺纹抗剪强度的影响

对不同厚度及缺角的速生材试样,进行了顺纹抗剪强度的测定。测试结果表明:3种厚度的杉木和茅栗径面试样的抗剪强度,在0.05水平上经t检验差异均不显著;缺角试件在0.01、0.05、0.001水平上经t检验差异均显著至极显著。为木材顺纹抗剪强度的测定,提供了调整试样宽度和径面厚度的参考依据。     

浸渍后处理及干燥处理对木材树脂浸渍改性效果的影响

【目的】探讨不同浸渍后处理方式和干燥方式对MUF树脂浸渍材增重率和尺寸稳定性的影响,为树脂浸渍改性技术提供参考和借鉴。【方法】利用5%、10%、15%和25%浓度的MUF树脂真空加压浸渍毛白杨木材,每种浓度树脂浸渍后试样首先分别进行4种方式浸渍后处理(气干处理7天、高湿度环境中平衡处理7天、树脂溶液中平衡处理7天以及不进行气干或平衡处理),然后分别利用2种干燥方式(直接干燥和湿干燥)进行干燥处理,干燥处理后测量不同处理条件下树脂浸渍材的增重率和容胀率,最后将素材和树脂浸渍材置于蒸馏水中常压浸渍14天,测试树脂浸渍材的抗胀率和径弦向差异湿胀程度。【结果】木材增重率与树脂浓度呈正相关关系,4种浓度树脂浸渍后试样增重率分别为9.7%、19.1%、28.4%和50.0%;不同浸渍后处理试样间的增重率差别不大;相同浸渍后处理条件下,直接干燥试样的增重率略低于湿干燥试样的增重率。树脂浸渍后,置于高湿度环境或树脂溶液中处理的试样,细胞壁容胀率较高;相同浸渍后处理条件下(除气干处理外),直接干燥试样的细胞壁容胀率低于湿干燥试样的细胞壁容胀率。树脂浸渍材抗胀率的变化规律与其细胞壁容胀率的变化规律基本一致。随着增重率增加,树脂浸渍材的径弦向湿胀率均降低,而其径弦向差异湿胀程度呈增加趋势,低增重率时试样的径弦向差异湿胀程度低于素材,而增重率超过30%左右时试样的径弦向差异湿胀程度高于素材。【结论】1)相同浓度树脂浸渍条件下,干燥方式对增重率的影响大于浸渍后处理方式,湿干燥处理有利于树脂在木材内部良好固着,从而获得更高的增重率;2)细胞壁容胀率受浸渍后处理方式和干燥方式二者的共同影响,置于高湿度环境或树脂溶液中的浸渍后处理有利于树脂继续扩散到木材细胞壁,湿干燥处理有利于树脂进一步扩散到木材细胞壁中并良好固着,从而对细胞壁产生更好的容胀效应;3)树脂浸渍材的抗胀率与细胞壁容胀率密切相关,树脂对细胞壁的容胀是树脂浸渍材尺寸稳定性提高的前提;4)树脂浸渍材的径弦向差异湿胀程度随增重率增加而有所增加。     

东北落叶松不同器官的热值和灰分含量分析

植物热值是森林生态系统中物质循环和能量转化评价的重要指标。利用假设检验和回归分析方法,对东北落叶松不同器官的热值和灰分含量进行了研究。结果表明:林木不同器官的热值和灰分含量在统计上大都存在显著差异,去灰分热值从大到小排序为叶(21.57 kJ/g)﹥枝(20.98 kJ/g)﹥皮(20.73 kJ/g)﹥根(19.88 kJ/g)﹥干(19.51 kJ/g),灰分含量排序为叶(5.79%)﹥皮(2.48%)﹥枝(1.88%)﹥根(0.95%)﹥干(0.47%);树干热值和灰分含量随树干从下往上呈增加趋势,且上、中、下部均存在显著差异;树根热值和灰分含量从根茎、粗根到细根也呈增加趋势,且两两之间差异显著;地上部分的平均干质量热值、去灰分热值和灰分含量均大于地下部分(树根),且差异显著;不同器官的热值和灰分含量与林木直径、树高和起源等因子显著相关,但其影响程度不尽相同。     

厚壁毛竹热值与生物量分配规律初探

厚壁毛竹是一个遗传性状稳定的基因突变体,竹壁特厚,是众多毛竹变异类型中唯一的材、笋兼优的栽培品种.本文对其生物量及热值进行测定.结果表明:竹子地上部分重量以竹杆为主.叶子的重量仅次于竹杆.其重量从大到小的关系依次为:杆＞叶＞蔸＞枝,且随着杆与地面距离变大,杆的质量呈减小趋势,胸径和竹高以及其综合作用对厚壁毛竹生物量的影响均达差异显著性水平;热值分布规律:叶4 808卡/克,枝5 019卡/克,杆5 622卡/克,且厚壁毛竹的各部分热值明显高于毛竹各相应部分的热值;经方差分析,不同部位对厚壁毛竹热值的影响并没有达差异显著;对供试样品的水分含量进行测定,得出各部分含水量关系为:蔸＞叶＞杆＞枝;密度关系为:枝＞蔸＞叶＞杆,且绝干密度接近新鲜时密度的1/2.     

三种规格材圆钢钉拔出握钉力性能研究

借鉴国家标准GB/T 14018—2009"木材握钉力试验方法",通过对横截面为38 mm×50 mm的国产日本落叶松、兴安落叶松和进口云杉三种规格材拔出握钉力性能进行试验,分析木材切面、圆钢钉直径及规格材种类对拔出握钉力性能的影响。研究结果表明:日本落叶松规格材三切面的拔出握钉力大小依次为弦切面径切面端面,且端面拔出握钉力的变异系数明显大于径切面和弦切面;日本落叶松规格材各切面的拔出握钉力及其变异系数均随钉直径的增加而增加;三种规格材试样的拔出握钉力性能为:日本落叶松兴安落叶松云杉,且兴安落叶松规格材握钉力的变异系数较大而云杉规格材较小;木材切面、钉直径和规格材种类对木材圆钢钉拔出握钉力均具有极显著影响,该研究中的木材拔出握钉力三个影响因子的效应大小为:钉直径木材切面规格材种类。     

施肥对麻栎生物量及热值的影响

研究不同施肥模式试验对麻栎生物量及热值的影响。结果表明:不同施肥水平对麻栎树高、地径生长均具显著差异,且增加幅度随施肥量的增加而增加;不同施肥水平总生物量和热值差异显著,不同生物组分热值大小顺序为树叶树皮树枝树干树根,施肥量为0.45 kg/株时生物量、热值最大。     

Growth and fuelwood properties of five tree and shrub species in the Sahelian and Sudanian ecozones of Mali: relationships with mean annual rainfall and geographical coordinates

In the Sahelian and Sudanian ecozones of West Africa, the rainy season lasts only 3–4 months per year, there are steep rainfall gradients with latitude and longitude, the climate is becoming increasingly hotter and drier with more variable rainfall, some fuelwood species are disappearing locally, demand for fuelwood is increasing, and we expect that fuelwood production will be increasingly limited to drier sites in the future. We need a methodology, therefore, to identify the best species for fuelwood production in drier sites. We used a methodology that could be used to identify the best fuelwood species for drier and wetter sites in regions where there are steep rainfall gradients. We investigated variation in growth and fuelwood properties of five species (Balanites aegyptiaca, Combretum glutinosum, Guiera senegalensis, Piliostigma reticulatum, Ziziphus mauritiana) along rainfall gradients. Growth parameters (tree height, stem diameter under bark, mean ring width) and fuelwood properties (basic density, volatile matter, fixed carbon, ash content, moisture content, gross calorific value, gross calorific value per cubic meter, fuel value index) were adjusted for tree age. For each species, linear regressions were used to determine the effects of mean annual rainfall and geographical coordinates, which were correlated with rainfall, on tree growth and fuelwood properties; and the effects of tree growth on fuelwood properties in lower, intermediate and higher rainfall zones. Geographical coordinates explained more variation than rainfall, and relationships with rainfall differed among species. Larger trees had wood with higher basic density, fixed carbon, ash content, moisture content, gross calorific value and/or gross calorific value per cubic meter, but lower volatile matter and/or fuel value index. Relationships between growth and fuelwood properties were not significant in all species and rainfall zones. Based on this study, we recommend producing fuelwood of C. glutinosum and G. senegalensis.     

Evaluation of fuelwood quality of indigenous and exotic tree species of India's semiarid region

The fuelwood potential of indigenous (Acacia nilotica, Azadirachta indica, Casuarina equisetifolia, Dalbergia sissoo, Prosopis cineraria andZizyphus mauritiana) and exotics (Acacia auriculiformis, A. tortilis, Eucalyptus camaldulensis andE. tereticornis) trees were studied. Calorific value variations for components, such as, stump, main stem, treetop, branches, foliage and bark, were determined. Tree components differed highly significantly (P<0.01) among groups (indigenous and exotics) and within species. The calorific means ranged from 18.7 to 20.8 MJ/kg for indigenous tree species and 17.3 to 19.3 MJ/kg for exotics. Besides calorific values, other fuelwood characteristics, such as, density, ash, biomass/ash ratio, moisture and nitrogen content were also studied. It was observed that indigenous tree species are better suited as fuelwood species as they contain high density wood, low ash content and low N percentage. The fuelwood value index (FVI) was found to be high of indigenous tree species and was maximum forCasuarina equisetifolia (2815). The most promising tree species were in the order ofC. equisetifolia, A. nilotica andZ. mauritiana.     

Impact of fuelwood quality and quantity on the energy use of rural households in the Omusati Region,north-central Namibia

The relation between fuelwood use and fuelwood quality and quantity was studied in two northern Namibian rural communities with different levels of fuelwood availability. Household surveys were conducted and fuelwood quality was assessed through laboratory studies. The study found differences in fuelwood use and adaptation of liveli-hoods to fuelwood availability. Where there was an abundance of quality fuelwood, the community chose fuelwood intuitively in accordance with the optimum physical properties and in a sustainable way. A fuelwood shortage, however, was found to impact negatively on work and social practices and fuelwood was collected through destructive harvesting practices, such as the cutting of green branches, and without consideration for optimum timber properties, such as tree age and calorific value.     

生物质流态化气化技术研究

论述了在锥形流态化气化炉内，对生物质原料进行气化和催化气化的工程化应用试验研究。研究结果表明：麦草原料气化所产生的煤气热值比稻草和稻壳都高，木屑气化所产生煤气热值最高，非催化气化条件下，流化床气化产生的煤气热值比下吸式气化炉产生的煤气热值提高40％左右；催化气化试验发现，CaO能明显提高煤气热值、降低C0组分，Na2CO3催化气化能提高气体H2的含量。但是对气化产生的气体热值，流态化空气气化中，在710℃以下低温时，无明显的影响，当温度达到800℃时，添加催化剂能明显提高气体的热值。     

Fuelwood demand and supply in Rwanda and the role of agroforestry

Fuelwood in Rwanda is assumed to come from forests and woodlands, thus contributing to large-scale deforestation. Available studies on fuelwood demand and supply support this assumption and indicate a continuously rising demand of fuelwood, notably from forest plantations. These assertions are insufficiently substantiated as existing forest stock may not be depleted by rapid increase in demand for food and energy resources resulting from population growth, but rather from the need for agricultural land. Evidence suggests that the demands for fuelwood, in addition to other sources of energy, is supplied from agroforestry systems which has not been quantified so far. This review analyses sources and use of fuelwood in Rwanda, indicating the importance of on-farms trees and woodlots in fuelwood supply. It is concluded that the effect of fuelwood consumption on land use is difficult to disentangle as many other factors including land clearing for agriculture, livestock farming, human settlements, illegal cutting of valuable timber species, the demand for charcoal in towns and past conflicts, contributed significantly to the high rate of deforestation in the country. If fuelwood demand is to be met on a sustainable basis, more fuelwood has to be produced on agricultural lands and in forest plantations through species site matching and proper management.     

Effects of region, soil, land use, and terrain type on fuelwood properties of five tree/shrub species in the Sahelian and Sudanian ecozones of Mali

? Context

There is little information about inter- and intra-specific variation in fuelwood properties of trees/shrubs in West Africa.

? Aims

We studied variation in fuelwood properties of Balanites aegyptiaca, Combretum glutinosum, Guiera senegalensis, Piliostigma reticulatum, and Zizyphus mauritiana in the Sahelian and Sudanian ecozones of Mali.

? Methods

Trees were sampled on different soil (sandy, sandy/loam, or rocky), land use (parkland agroforest or woodland), and terrain (flat, temporarily flooded, or hill slope) types in five regions extending from the drier eastern to the more humid western parts of Mali. Basic density, volatile matter, fixed carbon, ash content, moisture content, gross calorific value, and fuel value index were measured for each tree and adjusted for tree age.

? Results

All fuelwood properties differed significantly among species, but there were significant species by region interactions. Most fuelwood properties of four species differed significantly among regions. Soil and/or land use type had significant effects on a few fuelwood properties of four species.

? Conclusion

In general, fuelwood production is recommended in all regions for G. senegalensis, in drier regions for B. aegyptiaca and C. glutinosum, in more humid regions for Z. mauritiana, and on rocky soils for all species. Fuelwood production of P. reticulatum is not recommended.     

海南省中北部丘陵地区优良速生薪材树种的选择

海南省中北部贫瘠丘陵地区20个薪材树种，经4年选择试验，结果表明，马占相思、赤桉、细叶、大叶相思和斑皮桉适应性强，生长快，产量高，燃烧性能性，发热量大，用途广，经济效益高，年年均干生物量为17．5－23．9t/ha，纯利润为1199－2064元／ha，是最适合于当地生长和发展的优良速生薪材料种。     

经济林农作经营系统及其研究

本文从经济林生产的经济和生态两大功能出发,对经济林农作经营系统进行了综合性研究。提出了经济林农作经营系统的主要模式结构及主要特点,分析了经济林农作经营系统的建立原则和建立过程,还探讨了系统的生态经济效益及评估。     

Fuelwood characteristics of tree species in homegardens of Kerala, India

Indiscriminate use of natural resources in the past has lead to fuelwood shortages in many parts of the tropical world. To surmount this domestic energy crisis, not only degraded sites must be planted with trees having high fuel value potential, but also agroforestry promoted on arable lands. To enable choice of species for such energy plantations/agroforests in the humid tropics of peninsular India, we assessed the heat of combustion and physical properties that determine combustion of phytofuels, such as ash content, specific gravity and moisture content. Bark and wood samples of 45 multipurpose tree species in the homegardens of Kerala, India and three fuel materials of local importance (coconut [Cocos nucifera] endocarp, dried coconut spathe and dehiscent rubber [Hevea braziliensis] pericarp) were evaluated. Variations abound in the calorific values and physical properties of species and tissue-types. In general, heat of combustion and specific gravity followed the sequence: heartwood > sapwood > bark, while mean ash percentage followed a reverse order (bark > sapwood > heartwood). Ash content had a negative correlation with heat of combustion, but specific gravity exerted a positive influence. Furthermore, ash content and wood specific gravity were inversely related. Although green moisture content increased in the order: bark < heartwood < sapwood, it failed to show any predictable relationship with heat of combustion.This revised version was published online in November 2005 with corrections to the Cover Date.     

三北防护林体系工程发展现状及对策

为了改善生态环境,中国政府于１９７８年开始在三北地区建设林体系。１５年来,共计完成人工造林１３３０ｈｍ＾２,零星植树３０亿株,森林被覆盖率已由１５年前的５．００５％提高到８．６％,不仅取得了明显的生态效益和经济效益,也走出一条有中国特色的林建设道路。今后的发展对策为：强化政府行为;调整经济政策;优化林种树种结构;增加科技含量。