生物质型煤技术进展

综述了生物质型煤的典型工艺,与热压成型相比,冷压成型制备的型煤不具备防水性;较详细地介绍了型煤黏结剂;并对生物质型煤制备的几个关键参数做了较详细的比较;然后对生物质型煤的燃烧和其他利用途径做了介绍。最后,展望了生物质型煤的发展方向,在研究工业运用范围广的生物质型煤的同时,寻找来源广泛、可再生的复合型黏结剂,以提高生物质型煤的各项性能。     

冶金炉窑用高强型煤黏结剂优配的实验研究

以湖南金竹山无烟煤为原料，采用正交实验法对冶金炉窑用型煤复合黏结剂各组分的配比及型煤成型的主要工艺参数进行了实验研究．结果表明，镁基黏结剂和成型压力对型煤的抗碎性能影响显著．型煤黏结剂各组分相对于原料煤粉的最优配比为：镁基黏结剂取4％，生物质纤维取1％，固化剂取0．6％，减水剂取0．12％．型煤成型的最佳工艺参数为：成型压力20kN，成型水分17％，烟煤掺量10%，煤料粒度组成：3mm～2mm颗粒为8％，2mm～1mm为12％，1mm～0．5mm为10％，0．5mm以下为70％．评估了该复合型煤黏结剂的成本，分析了其作用机理．     

煤与牛粪生物质混合成型的研究

为了解决牛粪的利用问题,利用牛粪自有的木质素、纤维素、半纤维素等的黏结作用,将牛粪与煤经过中低压型煤成型机压制成型。研究了黏结剂与原料性质对生物质型煤强度的影响。结果表明:随着黏结剂添加量的增加,型煤强度逐渐增加,当黏结剂添加量超过10%时,型煤强度增加幅度逐渐变缓,黏结剂添加量不宜超过15%;随着无机黏结剂配比的增加,型煤强度先快速增大后缓慢降低,当黏结剂配比为5%有机黏结剂+6%无机黏结剂时,型煤强度最高;随着煤样粒度的减小,牛粪湿度的增加,型煤强度逐渐增加。最后分析了牛粪添加量对型煤燃烧性能的影响,说明生物质添加量越多,型煤初期燃烧速度越快,生物质添加量由20%增加到80%时,型煤燃烧速度变化不大。     

BCFC的制备和成型机理及燃烧特性

通过实验确定了生物质煤基燃料炭(BCFC)的制备工艺,研究了BCFC的成型机理和燃烧特性.结果表明,BCFC的制备工艺是将禹州煤、玉米秸秆和黏结剂按照81∶6∶13的质量比混合成型,再经700℃炭化处理.生物质型煤的内部结构、禹州煤和有机黏结剂的黏结性是BCFC成型的保证.市售燃料炭在燃烧初期燃烧强度较大,但持久性逊于BCFC,这与二者挥发分、固定碳和发热量的差异有关.     

黏结剂掺合比和配煤比对煤泥成型的影响

以石槽村煤泥为主要原料进行冷压成型制备型煤,采用单因素实验和正交实验等方法,重点研究黏结剂掺比和配煤比对型煤质量的影响.结果表明,添加少量的A或D黏结剂即可使型煤具有良好的冷压强度.配煤比和D黏结剂掺比是型煤质量指标的主要影响因素,D可与煤粒固化形成高强度的型煤“骨架”,但会增加型煤灰分,降低其发热量;配入原煤可提高煤泥型煤发热量,降低灰分,但会降低型煤强度.煤泥单独进行成型时,较优的黏结剂配方为:A掺比5％或D掺比4％;配煤成型时,以配煤比为8(煤泥)∶2(原煤)、D掺比7％为宜.     

腐植酸型煤制作与制气控制

1腐植酸型煤的制作 1．1腐植酸型煤成型原理粉煤黏结成型是指粉煤和外加黏结剂充分混合均匀后,在一定的压力下压制成型的过程。其黏结剂的选择关系到型煤的质量及成本,是型煤规模化生产的制约因素,因此粉煤成型关键是煤与黏结剂间的相互作用。     

生物质型煤优化配比研究

原煤选用无烟煤,生物质选用玉米秸秆,黏结剂选用黄土,制备生物质型煤.以挥发分和发热量为指标,参考以往对生物质型煤优化配比方面的研究,结合"实验优化设计与分析"方法自身的特点,采用二元二次回归正交组合设计方法研究生物质型煤的配比,得到了实验指标与各组分之间的回归方程,并求出了优化配比.研究所得的优化配比对生物质型煤的生产具有实际意义.     

低阶烟煤制取型煤的成型机理研究

选用水玻璃、膨润土和赤泥三种无机黏结剂,分别以四种不同的掺入量和低阶烟煤粉煤混合制取型煤.对型煤样品进行抗压强度的测定表明,型煤抗压强度随黏结剂掺比增大而增大,其中以膨润土为黏结剂的型煤强度远高于以水玻璃和赤泥为黏结剂的型煤强度,进一步的型煤微观结构电镜分析也证实了以膨润土为黏结剂的型煤其黏结性能相对最好,电镜切片表明,膨润土以朵状凝胶体楔入煤粒孔隙中并在煤粒表面形成整体网状结构.由于低阶烟煤自身的性质,以其制取的型煤往往对成型压力比较敏感,实验表明型煤的冷强度随成型压力的增大先增大后减小,存在一个最优成型压力.     

改性生物质作为型煤黏结剂的研究

探讨了用NaOH改性生物质秸秆作为型煤黏结剂的可行性,考察了NaOH溶液浓度对生物质改性的影响以及生物质添加量、无机物(MgO和MgCl2)添加量对型煤机械强度、防水性能和着火温度的影响。研究结果表明,NaOH改性液的质量分数为1.0%~2.0%时,制得的生物质型煤有较高的机械强度;生物质添加量在2%~20%时,随生物质添加量的增加,机械强度增加,着火温度降低,但防水性较差;而在生物质型煤中加入适量无机黏结剂后,型煤有很高的浸水强度,表现出优越的防水性能。     

生物质型煤发展综述

生物质型煤是将煤炭与农林废弃物等可燃生物质及添加剂按一定比例混合压制而成的一种固体成型燃料,是煤炭资源的一种洁净利用方式。生物质型煤技术将中国有限的煤炭资源和农村大量的可再生秸秆林木废弃物结合起来,不仅可以实现煤炭尤其是低阶煤的高效清洁利用,而且可以实现农林废弃生物质的资源化和能源化利用。从发展生质型煤的意义、生物质型煤成型的工艺、黏结剂的选用、燃烧机理以及燃烧特性作了综合叙述,并对生物质型煤发展前景进行了展望。发展生物质型煤,对减小大气污染、改善生活环境、缓解国家能源安全危机和实现中国化石能源与可再生能源的合理利用具有重要的战略意义。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.