Chemical dehydration coupling multi-effect evaporation to treat waste sulfuric acid in titanium dioxide production process

In order to concentrate the diluted sulfuric acid from the titanium dioxide(TiO2)production of sulphate process,a new concentration process was proposed by coupling chemical dehydration and multi-effect evaporation.The ferrous sulfate monohydrate(FeSO4·H2O),as the dehydrant,was added to the diluted sulfuric acid to form ferrous sulfate heptahydrate(FeSO4·7H2O)according to the H2SO4-FeSO4-H2O phase diagrams,which partially removes the water.This process was named as Chemical Dehydration Process.The residual water was further removed by two-effect evaporation and finally 70 wt%sulfuric acid was obtained.The FeSO4·H2O can be regenerated through drying and dehydration of FeSO4·7H2O.The results show that FeSO4·H2O is the most suitable dehydrant,the optimal reaction time of chemical dehydration process is 30 min,and low temperature is favorable for the dehydration reaction.45.17%of the entire removed water can be removed by chemical dehydration from the diluted sulfuric acid.This chemical dehydration process is also energy efficient with 24.76%saving compared with the direct evaporation process.Furthermore,51.21%of the FeSO4 dissolved originally in the diluted sulfuric acid are precipitated out during the chemical dehydration,which greatly reduces the solid precipitation and effectively alleviates the scaling in the subsequent multi-effect evaporation process.

Morphology and Growth Process of Bat-like ZnO Crystals by Thermal Evaporation

A novel bat-like ZnO nanostructure was synthesized on the silicon substrate by simple ther- mal evaporation of zinc powders without any catalyst. Each bat-like nanorod （＂nanobat＂） is composed of a hexagonal head, a continuous neck and a thin handle. High-resolution transmission electron microscopy and selected area electron diffraction results reveal the single-crystalline feature and the growing direction along [0001] of the nanobat. The vapor- solid mechanism was found suitable to explain the growth process of the nanobat and a schematic model was proposed in detail based on the experimental results.

EVAPORATION BEHAVIOR OF COMPONENTS IN Ti-15-3 MELT DURING ISM PROCESS

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Study on the mechanism of isotope fractionation in soil water during the evaporation process under equilibrium condition

In this study, with the method of vacuum extraction, two evaporative processes of soil water and free water under equilibrium condition were simulated. For each sample,water vapor was condensed by liquid nitrogen and was collected in four time intervals. From the analysis of hydrogen and oxygen isotopic compositions of the water collected at different times, it was discovered that the isotope fractionation of soil water also follows the mode, which is just the same as the evaporative process of free water. The relationship between the stable hydrogen and oxygen isotopes in residual water showed that the simulative evaporation line was close to the global meteoric water line (GMWL) under the equilibrium condition at about 20℃. Comparison of the two types of evaporative processes indicated that the isotope fractionation and evaporation velocity of soil water were only slightly modified by the Van der Waals force.

Critical and Impeding Pressures of Al Evaporation during ISM Processing of NiAl

In this paper, the critical pressure pcrit and impeding pressure pimpe of the elemental evaporation were defined and studied based on the calculation of the relationship between the evaporation loss rate Nm and the chamber pressure p during melting of NiAl alloys. When the chamber pressure is lower than pcrit or higher than Pimpe Nm tends to be the maximum or minimum value and remains almost unchanged. However, declines sharply with the increase of the chamber pressure when pcrit<P<Pimpe. A method has been put forward to calculate the pcrit and pimpe of Al evaporation in a Ni-XAI (x=25-50 at. pct) melt. The calculation result shows that the pcrit or pimpe is a second-order function of the molar percentage of Al and the melting temperature.

Study on the Isothermal Evaporation Process at 5℃ with the Brine of Laguocuo Salt Lake

1 Introduction Tibet has nurmerous salt lakes.Laguocuo is one of the salt lakes,which is located to the sorthern of Ali Plateau,31°59′02″N-32°04′08″N,84°02′03″E-84°12′03″E.Its lake water is rich in potassium,magnesium,lithium,boron,rubidium,cesium and other resources.The study of

Evaporation of multi-components in Ti-25Al-25Nb melt during induction skull melting process

Based on activity calculation model, the activity coefficients of Ti, Al and Nb components of Ti 25Al 25Nb (mole fraction, %) melt, the vapor pressures of corresponding components and the evaporation loss rates were calculated. Utilizing these activity coefficients and the vapor pressures, the relative evaporation coefficient is used to judge the evaporation tendency of these components. The evaporation tendency among the three components were compared and the result shows that the evaporation tendency is that: AlTi>Nb. Evaporation loss rate increases with the increase of melting temperature and decreases with the increase of chamber pressure. There exists an impeding pressure p impe of Al element evaporation during induction skull melting process of Ti 25Al 25Nb alloy. The impeding pressure can be written as p impe =8.1 p e, where p e represents the equilibrium partial pressure. The calculation of evaporation loss of Al element also showed that when chamber pressure exceeds p impe , the Al volatilization losses could be ignored. In order to prevent the evaporation loss of components, the pressure in the vacuum chamber should not below p impe .

An efficient preparation of porous polymeric microspheres by solvent evaporation in foam phase

This paper reports an efficient method of preparing porous polymeric microspheres by solvent evaporation in foam phase,in which phase separation between polymer and porogen occurs in foam phase instead of that in water phase by using the traditional solvent eva poration method.The method provides outstanding features,including being time-saving,of high-yield and able for continuous production,in which formation of porous polymeric microspheres finished within 3 min with a high production yield up to approximate 95 wt% and the process was able to be developed into a continuous process for production of porous polymeric microspheres.It was also universal to non-crosslinked polymers since the method is a development on the traditional emulsion solvent evaporation method.The new method is efficient and can be used potentially on the industrial scale for continuous production of porous polymeric microsphere s.

Case Studies of Heat Integration of Evaporation Systems

In this paper, through two case studies, evaporation systems are considered in the context of overall process, and then are optimized to obtain energy-saving effect. The possible evaporation schemes are given when integrated with the background process and how to optimize the evaporator is shown. From the case studies, it can be seen that sometimes incomplete integration and heat pump evaporation are better than complete integration so should be considered as candidate retrofit schemes.

Model for Periodic Analysis of the Quantity of Water Evaporated during Thermo-processing of Clay Designated for Production of Oven Refractory

A model has been derived for periodic analysis of the quantity of water evaporated during thermo-processing of clay designated for production of oven refractory. The model;γ = exp〔〔lnt/2.9206〕1.3〕 shows that the quantity of evaporated water during the drying process is dependent on the drying time, with the evaporating surface being constant. It was found that the validity of the model is rooted on the expression lnγ = (lnt/Logβ)N where both sides of the equation are correspondingly almost equal. The maximum deviation of the model-predicted quantity of evaporated water from the corresponding experimental value is less than 19% which is quite within the acceptable deviation range of experimental results. Water evaporation rate as obtained from experiment and derived model were evaluated to be 0.0536 and 0.0337g mins -1 respectively.

Separation of Lactic Acid from Diluted Solution by Hybrid Short Path Evaporation and Reactive Distillation

This work describes the separation and purification of lactic acid from diluted solution by HSPE （hybrid short path evaporation） and RD （reactive distillation） as coupled process. The results showed that it is possible to increase lactic acid concentration up to 4.7 times higher than the raw material concentration.

适用于共晶焊的肖特基二极管背面金属化工艺优化

[目的]为了降低成本,减少污染,提高工艺效率,对肖特基二极管背面金属化工艺进行研究,探索锡锑合金替代金系合金的最佳不持温镀膜金属化工艺.[方法]通过持温镀膜与不持温镀膜对比实验,分析电子束蒸发镀膜基片温度对阴极金属层间黏附性和导电性,以及薄膜厚度对空洞率的影响,得到适用于批量共晶焊的肖特基二极管背面金属化最优工艺参数.[结果]当基片温度为180℃时,不持温镀膜的剪切力为64.53 N,高于持温镀膜的剪切力;当金属化锡锑合金膜厚为3μm时,共晶焊的空洞率低于5%,符合共晶焊要求;电子束蒸发镀膜背面金属层方块电阻随基片温度升高先减小后增大,温度在180~240℃之间,方块电阻随基片温度的变化不大.[结论]用于共晶焊的肖特基二极管背面金属化的最优工艺为基底温度升到180℃后在自然降温的同时进行多层金属镀膜,锡锑合金镀膜厚度为3μm.

微波加热强化闪蒸工艺的科学基础及发展趋势

利用微波加热具有选择性、快速性、整体性等优点,对基于能量源补充热量实现蒸发浓缩、分离纯化的料液处理过程而言,利用微波加热实现过程强化具有现实意义。本文综述了液体闪蒸过程的蒸发特性与传热传质特性、微波加热液体蒸发的研究现状,提出了微波加热强化闪蒸工艺,首先指出闪蒸工艺过程中料液面临难以直接加热提供热量而提高蒸发速率的难题,原因是传统热量传递方法无法在真空条件下向闪蒸过程中的料液传递热量。进而分析了微波加热蒸发工艺的研究现状,总结出微波加热蒸发过程中的影响因素,简述了微波加热蒸发工艺的应用。最后,提出可将微波加热与闪蒸工艺相耦合的微波加热强化闪蒸工艺,简述了设备设计、应用开发方面的相关进展。总结了微波加热强化闪蒸面临的相关难题并提出建议,期望对微波加热强化蒸发工艺应用和设备设计的发展提供参考。

油田联合站水源热泵能效比软测量方法及节能效果研究

油田联合站水源热泵的应用既有效减少了以天然气为燃料的加热炉碳排放量,又解决了采暖伴热和机泵冷却的问题。但如何能精准方便测量和提高其能效比(COP)值,对水源热泵在油田推广应用有着重大意义。为此,采用BP神经网络对油田在运水源热泵的COP进行建模,测得与实际运行参数平均相对误差均小于1%,证明这种基于BP神经网络建模的水源热泵COP值软测量方法是可行的;另外,通过仿真模型分析,提出将水源热泵间接式单蒸发工艺改进为直进式双蒸发工艺,水源热泵COP值由3.6~4.2提高到4.5~4.8,年节约电耗174.1×104 kWh。研究结果对油田水源热泵的推广应用和系统节能降耗起到了积极作用。

Constructing core@shell structured photothermal nanosphere with thin carbon layer confined Co-Mn bimetals for pollutant degradation and solar interfacial water evaporation

Photothermal material applied in environmental governance has attracted growing attention.By combining the Stober method and dopamine-triggered coating strategy,Co-Mn precursor was in situ incorporated into the poly dopamine(PDA)layer over the surface of silica cores.Afterwards,a unique photothermal nanosphere with SiO_(2)core and thin carbon layer and dual Co-Mn oxides shell was allowed to form by sequential heat treatment in the inert atmosphere(SiO_(2)@CoMn/C).The bimetallic fraction of Co/Mn in the carbon layer and post-treatment calcination temperature was comprehensively tuned to optimize the peroxymonosulfate(PMS)activation performance of the catalyst.The state of bimetallic species was studied including their physical distribution,chemical valence,and interplay by various characterizations.Impressively,Co oxides appear as dominant monodispersed nanoparticles(~10 nm),while Mn with cluster-like morphology is observed to uniformly distribute over thin-layer carbon and adhered to the surface of SiO_(2)nanospheres(~250 nm).The calcined temperature could tune the oxidized state of Co species,leading to the optimization of the catalytic performance of introduced dual metal species.As a result,this obtained optimal catalyst integrated the advantages of exposed bimetallic CoMn species and N-doped thin carbon to deliver excellent catalytic PMS activation performance and photothermal synergetic catalytic mineralization ability for diversiform pollutants.Further reactions condition controls and anion interference studies were conducted to identify the adaptability of the optimal catalyst.Moreover,the application of solar-driven interfacial water evaporation using optimal SiO_(2)@Co_3Mn_1/C-600 catalyst was explored,showing a high water evaporation rate of 1.48 kg·m^(-2)·h^(-1)and an efficiency of 95.2%,further revealing a comprehensive governance functionality of obtained material in the complex pollution condition.

乳化溶剂蒸发法在递送体系中的应用

将生物活性物质载入递送体系可以改善其水溶性、稳定性和生物利用度,便于在食品、药品和化妆品等领域应用。乳化溶剂蒸发法是一种常见的制备活性物质递送载体的方法,具有使用条件温和,易于操作和放大,溶剂残留较低等优点。本文简要介绍乳化溶剂蒸发法,综述材料的选择和制备过程对所制载体的影响以及该法在制备活性物质递送体系中的应用研究进展,旨在推动乳化溶剂蒸发法的深入研究和实际应用。

织物中液态水传输与快干行为表征

为了能够保持运动中大汗淋漓时的舒适状态,研究液态水在织物中传输与快干性能是必要的。文章提出了织物中液态水传输与快干评价的指标,即滴水扩散时间、最大面积传输耗时、最大传输面积、经纬向最大传输跨距、蒸发速度等。液态水在织物中的传输行为通过观察其传输域变化来反映,呈现出与织物组织、纱线排列密度、纱线线密度、织物厚度、织物平方米质量等结构因素相关的初始阶段、增速阶段、稳定阶段和减缓阶段四个时期。通过对10种不同规格织物进行滴水扩散测试和水分蒸发速率测试,织物中液态水传输与织物厚度密切相关,织物厚度为液态水的渗漏提供空间但弱化了液态水的铺展和快干;纱线线密度影响织物表面孔隙,成为影响液态水铺展蒸发的主要因素;经纬密度通过与纱线线密度的匹配形成对液态水传输的影响。研究结果对于高品质运动服装面料的研发具有重要的指导意义。

基于磁控溅射和电子束蒸发合成Mn-Co-Ni-O薄膜

锰钴镍氧(Mn-Co-Ni-O,MCNO)薄膜因为具有优异的负温度系数特性在近年来受到广泛关注,现采用射频磁控溅射和电子束蒸发相结合的方式,在单抛蓝宝石(Al2O3)衬底上制备MCNO薄膜,并采用一系列表征探讨了后道退火(Post Annealing,PA)温度对所制薄膜的微观结构和光学性质的影响。结果表明,随着PA温度的提高,MCNO膜的晶粒尺寸和间隔均呈现增大趋势。X射线光电子能谱结果表明,Mn3+/Mn4+的比例随着温度的升高而增大。电学和光学特性研究表明,在PA温度为850℃,条件为空气退火1 h得到的MCNO薄膜在温度范围为220~300 K范围内符合VRH模型,TCR系数良好,激活能为0.32 eV,薄膜在红外可见波段具有较高吸收率。

Preparation of Co/S co-doped carbon catalysts for excellent methylene blue degradation

S and Co co-doped carbon catalysts were prepared via pyrolysis of MOF-71 and thiourea mixtures at 800℃at a mass ratio of MOF-71 to thiourea of 1:0.1 to effectively activate peroxymonosulfate(PMS)for methylene blue(MB)degradation.The effects of two different mixing routes were identified on the MB degradation performance.Particularly,the catalyst obtained by the alcohol solvent evaporation(MOF-AEP)mixing route could degrade 95.60%MB(50 mg/L)within 4 min(degradation rate:K=0.78 min^(-1)),which was faster than that derived from the direct grinding method(MOF-DGP,80.97%,K=0.39 min^(-1)).X-ray photoelectron spectroscopy revealed that the Co-S content of MOF-AEP(43.39at%)was less than that of MOF-DGP(54.73at%),and the proportion of C-S-C in MOF-AEP(13.56at%)was higher than that of MOF-DGP(10.67at%).Density functional theory calculations revealed that the adsorption energy of Co for PMS was -2.94 eV when sulfur was doped as C-S-C on the carbon skeleton,which was higher than that when sulfur was doped next to cobalt in the form of Co-S bond(-2.86 eV).Thus,the C-S-C sites might provide more contributions to activate PMS compared with Co-S.Furthermore,the degradation parameters,including pH and MOF-AEP dosage,were investigated.Finally,radical quenching experiments and electron paramagnetic resonance(EPR)measurements revealed that ^(1)O_(2)might be the primary catalytic species,whereas·O~(2-)might be the secondary one in degrading MB.

低温三效蒸发工艺中脱硫废水蒸发特性研究

脱硫废水蒸发特性是低温三效蒸发工艺参数确定的重要指标,通过蒸发实验,研究了脱硫废水蒸发速率与废水悬浮固、含盐浓度、密度间的关系,确定了系统最佳运行状态下的出料浓度。实验结果表明:脱硫废水悬浮固低利于废水蒸发,废水中固体颗粒可为盐分结晶提供晶种,颗粒冲刷作用降低了列管结垢风险,综合考虑蒸发效率和降低列管结垢风险,进水悬浮固建议为4%;脱硫废水蒸发速率随着含盐浓度的增加而降低,且含盐浓度越大蒸发速率降低得越快,可能与溶液黏度、溶液表面张力以及离子水合数有关;脱硫废水蒸发速率与溶液密度负相关,当溶液密度超过1400 kg/m^(3)时,蒸发速率显著下降,能耗明显增加,综合考虑系统高效运行和压滤机压滤效果,建议出料密度为1400 kg/m^(3)。浓缩倍率是低温三效蒸发系统工艺设计的重要指标,浓缩倍率与原水悬浮固负相关,应根据原水悬浮固及出料密度确定浓缩倍率进而完成三效蒸发系统总体设计。