煤粉O2/CO2燃烧时PM2.5及其Fe、S的生成特性

沉降炉实验研究了煤粉O2/CO2燃烧时PM2.5的生成特性和主要成灰元素中危害较大的Fe、S元素生成特性.实验用DT烟煤、NMG褐煤和XLT褐煤,实验温度1300℃,在O2/CO2=1:9,1:4,3:7和O2/N2=1:4气氛下燃烧.低压撞击器(DLPI)按不同粒径大小从0.03～9.8μm共分为13级,分别收集燃烧...     

电厂煤粉粒度特征及其对煤粒燃烧的影响

采用MS2000激光粒度仪分析了电厂炉前煤粉粒度分布特征，磨煤造成了显微组分的分离与富集，镜质组有向粗粒度富集的趋势，惰质组有向细粒度富集的趋势．较粗粒径煤粉（212μm～75μm）特别是212μmn～150μm粒度段所占比例对炉内煤粉燃烧效率的影响最大．虽然镜质组有向粗粒度富集的趋势，但最粗粒煤粉因颗粒太粗，在炉内短暂加热时间内来不及迅速燃烧；而较细粒煤粉则因磨煤引起惰质组向细粒度富集而影响其燃烧效率．所以，在理论分析和实验研究粒度对煤粒燃烧特性的影响时，应考虑磨煤造成的显微组分分离与富集所引入的干扰和煤自身煤岩特征的差异．     

58 MW煤粉工业锅炉空气分级燃烧试验研究

加快推进燃煤工业锅炉环保改造,有效降低煤粉工业锅炉大气污染物排放量,特别是降低NOx排放迫在眉睫。空气分级燃烧技术是一种减排效果显著,改造成本较低的低氮燃烧技术,已在电站锅炉得到成功应用。为考察空气分级燃烧技术在煤粉工业锅炉上应用效果,以煤科院某58 MW煤粉工业锅炉空气分级改造项目为研究对象,通过在侧墙上布置6个火上风喷口,实现空气分级燃烧。通过工程试验,采用特制水冷取样枪以及耐高温烟气分析仪,测量了该锅炉原工况(不采用火上风)与分级燃烧(采用火上风)工况下,炉内3个不同截面(每个截面10个取样点)以及双锥燃烧器内6个测点处烟气温度及烟气组分。结果表明,分级燃烧工况下,双锥燃烧器内在x=0.3 m测点后形成了高温、强还原性气氛,有效抑制了燃烧初始阶段NOx的生成。这是因为分级工况下双锥燃烧器内氧气被迅速消耗,焦炭燃烧反应速率显著下降,焦炭气化反应明显增强,故形成了较强的还原性,有效遏制了NOx的生成。炉内不同截面烟气温度及组成变化规律表明,原工况烟气温度分布整体呈现燃烧器射流中心高、外侧低的趋势,氧含量分布与温度分布趋势相反,而分级工况受双锥燃烧强还原性高速火焰以及火上风喷射的影响,截面温度波动较大,中间截面呈现燃烧器射流中心偏低的现象。分级工况在炉内形成明显的还原区,且表现为燃烧器射流中心CO浓度高、外侧低的现象,有效降低了炉内NOx生成。58 MW煤粉工业锅炉火上风空气分级低氮改造,在双锥燃烧器及炉内创造了合理的贫氧还原区,具有良好的低氮效果。     

大气有害颗粒物室内自然沉降实验研究

大气有害颗粒物(PM)对人体有极大的危害,紧闭门窗可使颗粒物自沉降,从而实现空气洁净。为研究室内有害颗粒物自然沉降的净化效果,该研究采用激光离散式颗粒物传感器与数据采集系统,对自然条件下室内大气有害颗粒物自然沉降进行实验研究。通过实验发现:室内大气有害颗粒物在重度污染(粒径小于2.5μm的PM150μg/m~3)浓度下,有较明显的自然沉降速率,PM粒径2.5μm～10μm、1.0μm～2.5μm、0.3μm～1.0μm自然沉降速率分别为:1.76μg/(m~3·min)、0.67μg/(m~3·min)和0.51μg/(m~3·min),当颗粒物为中度与轻度污染浓度时(150μg/m~3),自然沉降速率随浓度降低逐渐放缓;当密闭室内存在人员时,会加快室内大气有害颗粒物下降速率;此外,不同粒径的大气有害颗粒在空气中的分布均匀状态不同,粒径越大在空气中分布越不均匀,粒径越小越均匀,其在空气中自然沉降的速率越低。     

褐煤O2/CO2燃烧PM 10中重金属分布特性

通过在沉降炉中燃烧实验,研究了O2/CO2气氛下褐煤燃烧时PM10中重金属元素在颗粒物中的分布特性。结果表明,气氛对重金属元素分布的影响主要体现在亚微米颗粒范围内。与O2/N2燃烧相比,相同氧浓度O2/CO2燃烧PM10中的重金属向小粒径颗粒中富集。O2/CO2气氛下,氧浓度较低时重金属元素对亚微米颗粒物的生成贡献较大。     

煤焦燃烧过程中细模态颗粒物的生成机理及研究进展

实现燃煤颗粒物(PM)污染排放控制必须深入了解颗粒物排放规律及生成机理。煤粉燃烧过程中产生飞灰颗粒粒径分布为粗模态,细模态和超细模态3种。与粗模态PM相比,细模态PM占比较大,其小粒径与富集性特点影响人体健康及大气环境。同时,相对于形成过程与机理相对成熟的超细模态PM,细模态PM形成机理及研究进展尚缺乏系统总结,抑制细模态PM排放存在困难。笔者分析了细模态PM的形成机理(焦炭颗粒的破碎、矿物质熔融聚合、外在矿物质破碎、表面灰粒的脱落)及主要影响因素,探讨了模拟研究进展并指出未来研究重点。煤灰PM粒径分布主要是焦炭颗粒破碎与矿物质聚合行为这2个因素相互竞争的结果。破碎行为使得细模态PM数量增多粒径减小,而矿物质聚合使得PM数量减小,有利于粗模态PM形成。影响PM形成的主要因素有孔隙结构、燃烧模式与焦炭粒径。孔隙率较高的煤胞型焦炭相较于其他结构焦炭更易发生破碎,产生更多细模态PM。增加温度与氧含量,降低粒径均有助于PM生成,但较高温度下灰粒的聚合可能导致粒径分布倾向于粗模态PM。破碎行为对焦炭燃烧特性模拟大致分为群体平衡模型和逾渗模型2类。基于细模态PM形成机理与影响因素,认为逾渗模型考虑了焦炭本身孔隙结构,更适于模拟焦炭破碎行为。本征动力学燃烧模型与逾渗模型的结合是准确预测灰颗粒粒径分布的关键,是下一步的研究重点。     

小龙潭褐煤燃烧细粒子生成演化的实验研究

为了解煤燃烧过程中细粒子的分布特征和形成机理 ,进行了小龙潭褐煤的滴管炉燃烧实验 .收集的细粒子尺寸分布和形貌已经在不同的操作参数下进行了测量 ,由此得到细粒子的分布特征并探讨燃烧过程中温度对细粒子生成的影响 ,同时利用 SEM分析细粒子生成演化的过程 .煤粉燃烧细粒子的粒径分布呈典型的双峰分布 .不同燃烧温度下 ,细粒子尺寸的变化说明细粒子的形成机理是气化—成核—凝聚机理 ,并且测得的细粒子生成演化的 SEM图样与细粒子生成机理相吻合 .     

煤粉密度对燃煤过程中颗粒物形成特性的影响

通过浮选实验先将典型烟煤分成高、中、低3个密度段,然后对3种不同密度原煤在沉降炉内进行热解和燃烧实验,研究原煤密度对颗粒物形成机理和特性的影响。实验采用低压撞击器（LPI）把颗粒物按不同粒径大小从0.03～10.0 μm共分13级,分别采集燃烧后的可吸入颗粒物。实验结果显示：低密度原煤对颗粒物形成的贡献最大,中密度次之,高密度最小,低密度原煤所含矿物质粒度最小,形成的焦的膨胀率、总孔体积和BET表面积最大,高密度原煤所含矿物质粒度最大,形成的焦的膨胀率、总孔体积和BET表面积最小,中密度原煤介于两者之间,3种密度原煤燃烧后形成的PM10颗粒物元素构成的相同点是：对于亚微米颗粒物,元素S＋碱金属元素＋其他元素>难熔元素,对于超微米颗粒物,难熔元素占80%以上,远远大于其他三类元素。     

四角切圆锅炉富氧燃烧对NO_x生成影响的数值模拟

采用RFG富氧燃烧方法在新疆某电厂350 MW机组锅炉上进行数值模拟,对燃烧时炉内温度场、CO与O2及NOx排放进行分析。结果表明:在21%、25%、29%富氧燃烧工况下,NOx排放浓度均低于空气燃烧时的浓度;四角切圆燃烧煤粉锅炉采用富氧燃烧后,炉膛出口NOx浓度由空气燃烧时的359 mg/m3分别降低到235 mg/m3、272 mg/m3、305 mg/m3;高浓度的CO2与煤粉反应生成CO,形成还原性氛围,有助于抑制NOx生成以及增大对已生成NOx还原的概率;在氧气含量为21%的浓度下,通过增加循环烟气中NO含量可以减少NOx的生成和排放。     

神府煤粉燃烧特性

为了给煤粉锅炉用户提供煤粉优选理论依据,以煤粉锅炉主要用煤神府煤制备的煤粉为研究对象,采用TG-DTG对煤粉的燃烧特性进行研究,分析了不同煤粉及升温速率对煤粉燃烧特性的影响。结果表明:在空气气氛下,升温速率提高,TG、DTG曲线向高温方向移动,煤粉的着火温度升高,最大质量变化速率增大,最大失重温度提高,燃尽指数增大;随着灰分和粒径改变,升温速率为10或20℃/min时,煤粉的着火温度变化不显著,燃尽指数及综合燃烧特性指数均有影响。灰分减小,粒径不变时,D煤粉的综合燃烧指数为1.51,优于粒径74μm、灰分9.5%的P煤粉。     

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.     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。