林产废弃物热解生物油酯化-复配提质的研究

湖南是林业大省,具有丰厚的林产资源,其中林产废弃物通过热解技术获得可再生能源生物碳、燃气和生物油。本实验采用酯化和复配调和技术对生物油的提质进行了研究,首先自主合成的固体酸催化剂Al_2O_3-HZSM-5,通过XRD、FT-IR和SEM进行了表征分析,发现催化剂的晶型和结构完整,具有较大的比表面积和较多的活性点位,有利于催化酯化反应的进行。将其用于催化生物油的酯化反应,原料酸值降至1.09 mg KOH/g,再与甲醇复配获得改性燃料油,其热值为21.3 KJ/g,运动粘度3.4mm~2·s~(-1),可用于锅炉、燃油灶等粗放型设备的应用。     

西瓜有望成为乙醇燃料的新来源

第一代生物燃料以可食用作物为原料,主要包括玉米、大豆、甘蔗。但是这种对粮食作物的额外需求使得2008年家畜饲料价格大幅上升,第一代生物燃料显然并不是我们所期望的、对环境安全具有积极影响的能源形式。目前,科学家正致力于研究,怎样将农业废弃物、木材及生长更为迅速的草本植物,转化为种类繁多的生物燃料（甚至是航空燃油）。这就是第二代生物燃料,用植物或植物制品作为生物燃料的原材料。     

生物质催化转化制备生物基航空燃料的研究进展

生物质催化转化是制备高品质生物基航空燃料和解决能源危机的主要途径，本文从现有的生物基航空燃料的制备方法出发，从适应需求的原料和技术路线的角度，概述了油脂、木质纤维、糖类等不同的原料所需的技术路线和催化体系，以及加氢脱氧、费-托合成、羟醛缩合、烯烃齐聚等不同技术路线所用的催化剂，同时对反应条件以及反应机理进行优化和探索，并指明催化转化过程中存在成本高、工艺和转化机理复杂(高温和高压)、H₂用量高、目标产物的选择性较差以及催化剂失活等问题。最后，针对各种原料、技术路线的优缺点以及面临的问题，提出了建议并展望其未来发展方向。     

生物油精制技术研究进展

主要介绍了催化加氢、催化裂解、乳化、催化酯化、分子蒸馏这5种生物油精制方法。由于生物油精制技术都存在各自的问题,如:催化裂解具有设备简单、成本低等优点,但其催化剂容易结焦失活;乳化操作简单,但成本和耗能较多;催化酯化是一种较好的改性方法,但是改性后油的品质不高。这些都使生物油精制技术难以实现工业化。提出了一种在CO/H2O体系中精制生物油的新方法。     

Progress in Bio-oil Refining Technology

主要介绍了催化加氢、催化裂解、乳化、催化酯化、分子蒸馏这5种生物油精制方法.由于生物油精制技术都存在各自的问题,如:催化裂解具有设备简单、成本低等优点,但其催化剂容易结焦失活;乳化操作简单,但成本和耗能较多;催化酯化是一种较好的改性方法,但是改性后油的品质不高.这些都使生物油精制技术难以实现工业化.提出了一种在CO/H2O体系中精制生物油的新方法.     

生物质燃油的应用前景

从废弃生物质资源利用现状、生物质制燃油的转化技术、生物燃油生产成本预算、生物燃油的市场等方面阐述了应用生物质能的可行性,表明生物质燃油具有广阔的应用前景.     

NiMo/Al_2O_3-Pd/C组合催化剂催化热解油加氢制备供热燃料

采用催化加氢的方法,对热解油进行提质改性,以期作为供热燃料。以NiMo/Al_2O_3-Pd/C为组合催化剂,在一定温度(300℃)和压力(8 MPa)下,在间歇反应釜中进行热解油催化加氢实验。采用红外光谱(FTIR)、气相色谱-质谱(GCMS)对加氢油进行结构表征与组分分析;测试加氢油的产率、元素含量、H/C比和热值,分析组合催化剂对热解油的加氢提质效果。结果表明,经NiMo/Al_2O_3-Pd/C组合催化剂催化得到的加氢油,油产率达到41.08%,含碳量由55.21%提高至76.20%,含氧量由38.06%降低至14.09%,H/C比由0.28增加至1.14,热值达到36.24 MJ/kg,满足供热燃料的使用要求。     

Pd/C催化剂作用下生物质醇解重油的加氢精制研究

为解决生物质醇解过程产生的重油降低生物油品质的问题,考察了Pd/C催化剂作用下醇解重油的加氢精制。结果表明,在150℃时,Pd/C催化剂效率最高,在此温度下,重油加氢裂解所得轻油的产率达到38.01%(质量分数),同时,残渣产率亦最低,仅为2.59%,而且,加氢后的重油相对分子质量减小50%,同时氧含量也低于原来的50%。轻油组成的GC-MS分析结果表明,催化加氢使重油大分子裂解生成1-乙基-2-甲基-苯、甲基苯乙烯和苯酚等芳烃和酚类化合物,而且,也促进了重油结合的正辛醇溶剂的解离。     

Hydrogenation Refinery of Heavy Oil from Biomass Alcoholysis in the Presence of Pd/C Catalyst

为解决生物质醇解过程产生的重油降低生物油品质的问题,考察了Pd/C催化剂作用下醇解重油的加氢精制.结果表明,在150℃时,Pd/C催化剂效率最高,在此温度下,重油加氢裂解所得轻油的产率达到38.01％(质量分数),同时,残渣产率亦最低,仅为2.59％,而且,加氢后的重油相对分子质量减小50％,同时氧含量也低于原来的50％.轻油组成的GC-MS分析结果表明,催化加氢使重油大分子裂解生成1-乙基-2-甲基-苯、甲基苯乙烯和苯酚等芳烃和酚类化合物,而且,也促进了重油结合的正辛醇溶剂的解离.     

利用秸秆干式发酵生产沼气

专利号:200710043393.4目前,生物燃油主要是用化学法生产,即用动物和植物油脂与甲醇或乙醇等低碳醇在酸或者碱性催化剂和高温(230℃～250℃)下进行转酯化反应,生成相应的脂肪酸甲酯或乙酯,再经洗涤干燥即得生物柴油。甲醇或乙醇在生产过程中可循环使用,生产设备与一般制油设备相同。但化学法合成生物燃油有以下缺点:工艺     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。