结晶盐对蒸发生产的影响

在氢氧化钠浓度为10％左右的隔膜电解液蒸发的过程中,氯化钠几乎始终都在氢氧化钠溶液的饱和之中,每时每刻都有结晶析出的可能,可以这样说,解决蒸发系统生产的关键是解决盐的问题,这个问题解决得好,就可以保证蒸发系统工艺管道的畅通和设备的平衡运行,反之,则造成管道,阀门和加热室列管的堵塞,直接影响蒸发装置的正常运行。     

改善废酸浓缩分离装置蒸发器结垢堵塞的工艺优化研究

为解决废酸浓缩分离蒸发器运行过程中的结晶堵塞导致的换热效果降低、影响生产连续运行的问题,通过分析并优化工艺,延长了连续开车时间,节约了蒸汽消耗,提高了浓缩分离生产效率。运行结果表明,蒸发器管壁结垢有所改善,连续开车时间由原来的15 d延长到60 d以上,废酸蒸汽单耗由1.0 t/m~3降低到0.6 t/m~3,在一定程度上能够延缓硫酸钙在蒸发器内的结晶堵塞。     

蒸发结晶过程传热温差的选择

蒸发结晶是化工生产中常见的单元操作。蒸发结晶又分为单效蒸发和多效蒸发,大部分是靠加热的方式来进行的。在加热过程中,物料与加热介质（如水蒸气）之间的传热温差是很关键的因素,温差越高,传热效率也越高,并且可以提高设备蒸发能力。但是,传热温差过高会引起蒸发结晶操作的不稳定,不容易控制,物料粘壁,影响热量传递,甚至造成加热器堵塞,导致装置需频繁停车处理,不能连续稳定长周期运行。因此,必须合理选择传热温差,以保证生产装置在高效、稳定的状况下运行。     

含硫化钠废水制备无水硫化钠工艺研究

含硫化钠废水通过蒸发浓缩结晶可以得到硫化钠晶体,由于硫化钠在加热的水溶液中容易水解产生硫化氢,实际得到硫化钠晶体的收率很低。本文向含硫化钠废水中补加液碱,控制废水中氢氧化钠的质量分数6.0%～7.0%,可以有效抑制硫化钠在水溶液加热蒸发过程中的水解,通过蒸发浓缩结晶过滤,得到带结晶水的硫化钠晶体,再加热脱除结晶水可以得到无水硫化钠,通过结晶母液循环套用,无水硫化钠的回收率可以达到97.5%,具有较好的工业化应用前景。     

废酸喷雾浓缩装置的设计及制作原理

针对目前钛白废酸回收利用工艺存在的不足,提出了喷雾浓缩钛白废酸的技术方案,该技术方案具有传热效率高、设备费用低和不易堵塞的优点。根据喷雾干燥原理,探索了喷雾浓缩原理,为喷雾浓缩原理提供理论依据。研制出的喷雾浓缩装置可以一级将钛白废酸由质量分数为20%浓缩至80%以上,浓缩效果明显,具有较好的推广应用价值。     

单管填料升膜浓缩结晶脱盐法治理废酸液研究

单管填料升膜浓缩结晶脱盐法是一种治理废酸液的新工艺。介绍单管填料升膜浓缩结晶脱盐法应用真空浓缩法和加酸冷冻法工艺对钢厂废酸液的治理,治理过程中回收废酸中的H2SO4和FeSO4,并实现完全零排放。该工艺在我国具有广阔的应用前景。     

冶炼污酸蒸发浓缩处理的实验研究

铜冶炼的工艺烟气制酸环节产生污酸,其特点是含高浓度的氟、氯、砷,以及铜、锌、铅、镉等多种金属。目前采用的硫化沉淀-石灰中和的处理方法,存在产生大量难以处理的危险废物且处理成本高、出水水质难以达到回用要求等不足。本文针对该类污酸的特性,探讨采用蒸发浓缩法处理并回收砷,并后续回收硫酸以及其中有价金属的可行性。在常压加热蒸发条件下,实验研究考察了不同温度、浓缩比时污酸中氟、氯、硫酸根、砷在浓缩液及冷凝液中的走向及分布,以及不同蒸发比条件下浓缩液冷却结晶析出三氧化二砷的去除率。实验结果表明,污酸蒸发浓缩对砷、氟、氯均具有较好的去除率,蒸发温度在130℃、浓缩比6~7时,砷、氟、氯的去除率达到62%、88%、77%。蒸发浓缩处理实验研究表明,蒸发浓缩法处理污酸具有较好的应用前景。     

烟气蒸发结晶技术在脱硫废水零排中的应用

为降低石灰石-石膏湿法脱硫废水零排放运行成本、减少蒸汽消耗,根据高温未饱和原烟气的特性,从石灰石-石膏湿法脱硫的原烟气中引出一部分烟气,进入废水蒸发结晶塔,浓缩脱硫废水,使废水中可溶性盐浓缩、结晶,再经中和、沉降、分离出盐,滤液返回蒸发结晶系统,继续循环蒸发。盐主要成分为氯化钙、硫酸钙。经核算该工艺与现有"混凝沉淀预处理+蒸发结晶处理"工艺相比,无需预处理药剂、工艺水、蒸汽,没有特殊的设备,废水可在脱硫内部的循环利用,还具有投资省及运行成本低的特点。     

理化所热泵蒸发浓缩结晶技术产业化取得新进展

<正>机械蒸汽再压缩蒸发浓缩结晶技术(简称MVR)是国内先进的节能减排环保技术。该技术不仅可以大幅降低蒸发浓缩结晶工艺的能耗,降低碳排放,而且能够大幅减少蒸发浓缩结晶过程的运行成本,同时可大幅减少设备的占地面积。MVR系统广泛应用于工业废水处理、石油化工、食品加工、乳品工业、海水淡化、制药、制盐等行业和领域,市场前景十分广阔。     

不锈钢酸洗废液再生利用的工艺研究

不锈钢酸洗废液中含有大量可回收的硝酸、氢氟酸和铁资源,采用硫酸置换法回收其中的硝酸和氢氟酸,并通过减压蒸发、冷凝回收等过程得到再生混酸(HNO₃+HF)。对硫酸置换废酸工艺进行流程模拟,研究了不同硫酸加入量、蒸发能耗对酸洗废液蒸发温度、混酸回收率的影响,结果表明：适宜的硫酸和酸洗废液加入量比为0.625∶1.000,蒸发能耗以3.4 MJ/kg酸洗废液为宜,蒸发温度为102.4℃,氢氟酸回收率为99.95%,硝酸回收率为93.11%,回收的混酸中氢氟酸、硝酸的质量分数分别为3.98%和7.51%,再生混酸可回用于不锈钢酸洗生产线。废酸经蒸发、结晶处理后得到含铁、镍、铬等重金属的盐泥,盐泥可进一步分级利用处理,分步回收其中的铁、镍、铬等金属或委外处理。     

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.