三峰分形级配水煤浆提浓技术研究

水煤浆气化采用传统单磨机工艺制浆时存在煤浆浓度低、流动性和雾化性较差等问题,基于粒度级配理论方法,在水煤浆中加入细浆和超细浆,实现水煤浆三峰分形级配,分析了三峰分形级配水煤浆提浓技术理论,论述了三峰分形级配煤浆提浓技术在山西阳煤丰喜泉稷能源有限公司的工业应用情况。结果表明,采用三峰分形级配提浓技术后,水煤浆浓度由60. 10%提高到64. 19%,提高了4. 09%;有效气含量由79. 91%提高到82. 12%,提高了2. 21%;比氧耗降低了35 m~3/km~3,比煤耗降低了20 kg/km~3。吨合成氨耗煤量减小0. 05 t,吨煤增合成氨量增加0. 024 t。三峰分形级配提浓技术的成功研发使得水煤浆技术具有了制浆浓度高、煤种适应性宽、效率高、能耗更低的技术特点,将取代能耗高、效率低的常规棒磨机制浆工艺。     

三峰分形级配提浓技术在中煤陕西公司的应用实践

针对单棒磨机制浆工艺存在煤浆粒度级配不合理、煤浆浓度低、影响煤炭气化转化效率和能耗等问题,研发了三峰分形级配提浓技术。介绍了三峰分形级配提浓技术的原理,对比了采用三峰分形级配提浓技术前后煤浆的成浆性能,并将该技术应用于中煤陕西公司煤制烯烃项目煤浆制备系统,分析了项目实施前后的煤浆性能。结果显示:采用三峰分形级配提浓技术后,煤浆质量分数提高3.8～4.7个百分点,比煤耗、比氧耗分别降低40.76 kg/1 000 m~3、33.44 m3/1 000 m~3,有效合成气体积分数提高1.48～3.29个百分点,煤浆的稳定性和流动性明显改善。     

水煤浆粒度级配模型和实践的研究进展

水煤浆是一种煤基液态燃料,具有与燃料油相似的物理特性,是煤炭高效清洁利用的一个重要途径,可显著减少NOx和SO2的排放。目前我国水煤浆需求量已突破2.5亿t/a,粒度级配作为影响水煤浆浓度的重要因素,使不同大小的煤颗粒互相填充,尽可能减少空隙,提高颗粒的堆积效率和水煤浆浓度。分析了粒度级配对水煤浆的影响,指出在水煤浆制浆过程中,粒度级配只涉及物理破碎和研磨,能耗相对较小,显著提升浓度,具有广泛的适用性和经济性。论述了近年来新发展的粒度级配理论和模型,特别是隔层堆积理论和分形级配理论,并给出了具体的计算方法和公式,以及假设和适用性。通过举例给出近年来隔层堆积理论的发展和应用,以及对于堆积效率的具体评价;分析了分形级配理论的可行性和新的研究进展,以及在指导烟煤和褐煤级配时的应用效果;给出了三峰级配的工艺流程、级配方案和工业实践案例。在粒度级配提高水煤浆浓度的基础理论和应用实践方面,国内外学者已做大量工作。但在具体的理论细节方面,如隔层堆积对于任意粒度分布的简化计算、分形级配的拟合精度以及三峰级配的粒度堆积评价还需更深入的研究。在级配理论应用于实践过程中,基础理论和工业实践的结合还有待于进一步提高。在粒度级配基础上,建议引入内在水分等影响因素,建立跨煤种的预测模型。     

三峰分形级配水煤浆提浓技术研究

为提高煤炭气化转化效率,论述了三峰分形级配制浆技术原理和技术特点,通过实验室研究,对单磨机制浆工艺和三峰分形级配制浆工艺进行对比,分析不同工艺下制取的水煤浆成浆性能;在中煤陕西榆林能源化工有限公司原有单磨机制浆单元基础上采用三峰分形级配提浓技术进行工业示范,通过分析项目可行性、技术方案等,对比投产前后的运行效果。实验室研究表明,在单棒磨机制浆工艺条件下,添加0.18%的ZM型添加剂时,水煤浆浓度仅为61.4%,水煤浆粒度级配不合理、流动性和稳定性差。而在三峰级配工艺最佳配比85∶10∶5条件下,水煤浆浓度能提高至65.5%,与单棒磨机制浆工艺相比,浓度提高4.1%,且水煤浆流动性和稳定性显著改善。工业运行结果表明,相同条件下,水煤浆槽水煤浆浓度由改造前的61.7%提高至目前的65.5%,1 000 Nm~3CO+H_2比煤耗降低了40.76 kg;1 000 Nm~3CO+H_2比氧耗降低了33.44 Nm~3,有效合成气含量提高1.48%。采用三峰分形级配提浓技术后,气化水煤浆的煤浆质量及气化效率有显著改善。     

高浓度气化水煤浆制备技术

水煤浆气化有效气含量与粉煤气化相比,有一定差距,主要原因是水煤浆浓度偏低,气化时带进多余的水而造成。提高水煤浆浓度是提高水煤浆气化有效气含量的关键。介绍了近年来国家水煤浆工程技术研究中心开发的气化水煤浆提浓新技术,包括分级研磨制浆技术和间断粒度级配制浆技术。介绍了两种制浆技术的原理及工艺流程,工业应用及中石化联合会的科技成果鉴定表明,与常规制浆工艺采用同种煤制备的煤浆浓度相比,分级研磨制浆技术煤浆质量分数提高3个百分点左右;间断粒度级配制浆技术煤浆质量分数提高6~8个百分点。     

粒度级配对制备高浓度水煤浆的影响

选取典型低变质程度神木柠条塔(NTT)煤,进行球磨式连续型粒度级配提高水煤浆浓度(一定量的水煤浆试样在105℃~110℃干燥至恒重,干燥后试样质量占原样质量的百分数)和成浆性的研究。在不同球磨条件下,考察球磨时间、球磨速度对成浆浓度、流变特性和稳定性能的影响规律,研究粒度级配前后浆体表面润湿性、表面电负性、微观形貌的性能变化对NTT煤成浆性的影响,利用分形维数的计算,进一步探究了粒度级配对提高NTT煤制浆浓度的影响机理。结果表明:在级配M煤样(D50=79.02μm)与M₆煤样(D50=8.727μm)的质量比为8∶2时,成浆浓度与未级配煤样相比提高了约4%;不同球磨条件下的煤样按照不同的质量比进行混合制浆时,初始添加细颗粒使浆体表面的润湿性增强,降低了浆体的性能,当粗细颗粒的质量比大于6∶4时,表面润湿性的变化较小;级配样的成浆浓度与Zeta电位的绝对值呈正相关;当级配煤样之间粒径相差逐渐变大,小颗粒填充到大颗粒孔隙中,增加了空间堆积率,提高了制浆浓度,但随着细颗粒的质量分数增大,大颗粒孔隙被撑开,煤粒空间堆积率下降,制浆浓度降低;M煤样与M₆煤样在质量比为8∶2时,相比于其他级配浆体,分形维数达到最大(2.460),成浆浓度达到最高(63.03%)。     

分级研磨制备高浓度水煤浆技术研探

水煤浆气化技术已广泛应用于化工、发电及城镇燃气制备等领域。但是，在我国气化水煤浆制备行业中，目前大多数企业还采用的是单级研磨制浆（单磨制浆）工艺，这种工艺制备的水煤浆存在水煤浆粒度偏粗、级配不尽合理、浓度低等问题，直接影响水煤浆气化效率的提高。分级研磨制浆是相对传统单磨制浆开发的一项新技术，与传统单磨制浆相比，其制浆浓度可提高约3个百分点，在生产中能起到提高装置产能、降低气化氧耗和煤耗的作用。     

粒度级配对神府煤成浆性能的影响

为提高神府煤制备水煤浆的成浆性能,分析了神府煤的原煤性质,说明神府煤的成浆指标为11.55,属于很难成浆煤种。对不同粒度级配的干基煤样进行粒度分析,通过粗、细煤粉单独制浆实验和不同粒度级配煤粉的成浆性实验,研究了不同粒度级配对水煤浆成浆性的影响。结果表明:经过级配的干基煤样具有双峰粒度分布特征,适宜制浆;粗煤粉不能单独成浆,细煤粉单独制浆的最大成浆浓度为61%;粗细煤粉质量比约为1∶2时,水煤浆具有较好的流动性和稳定性,最大成浆浓度可达63.8%,此时水煤浆黏度为1000 mPa·s,符合工业水煤浆制备标准,说明合理的粒度级配可降低水煤浆黏度,增强流动性及稳定性。     

粒度级配对煤成浆质量分数的影响

水煤浆受煤的粒度、添加剂、不同煤种的内水分、煤种孔隙结构、含氧官能团和可磨性指数影响,成浆性能差别较大[1]。近几年由于油价和能源紧张,企业利润率较低,提高水煤浆浓度再次受到关注,水煤浆的粒度分布要求达到较高的堆积效率,即要求颗粒堆积时空隙小,而固体容积的浓度高,制备时使用单一粒径的煤颗粒很难达到高的最佳堆积效率。     

激光粒度仪分级测定水煤浆粒度分布的研究

为确定多种磨矿产品级配制得水煤浆样品的粒度分布,文章提出了分级测定水煤浆粒度的方法,已知各磨矿产品的粒度分布,通过分级拟合的方法得到不同质量比级配样品的粒度分布。结果表明:分级计算方法得到的煤样粒度分布可以准确反映出级配样品的峰型,且粒度测试结果较为准确。     

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.     

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.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.     

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.