共查询到19条相似文献,搜索用时 156 毫秒
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提出了带塔底储罐的间歇萃取精馏操作方式.新操作方式使精馏过程中加入的溶剂及塔内回流液直接流入塔底储罐,不再返回塔釜.以乙二醇为溶剂分离乙醇–水共沸物的实验研究表明,新操作方式克服了普通间歇萃取精馏塔釜体积庞大的缺陷,同时具有塔釜温度稳定、加热容易控制、收率提高等优点. 相似文献
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利用宽视场体视显微镜和CCD摄像系统对纯蒸发换热情形下竖直放置的矩形毛细微槽群热沉中的液体沿微槽槽道方向的流动情况和干涸点高度(润湿高度)进行了观察测量,并对微槽几何尺寸、工质等因素对润湿高度的影响进行了实验研究。实验结果表明:纯蒸发情形下的液体润湿高度随着输入加热功率的增加而陡降;一定热负荷下,微槽较深、较窄以及微槽群密度较大时液体的润湿高度较高;甲醇和乙醇在较低输入加热功率条件下的润湿能力要强于蒸馏水;竖直毛细微槽中液体的润湿特性受重力的影响严重。 相似文献
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Enhanced modeling of moisture equilibrium and transport in cementitious materials under arbitrary temperature and relative humidity history 总被引:2,自引:0,他引:2
This paper focuses on behaviors of moisture dispersed in nano‐macro scale pores under various temperature and relative humidity conditions. The authors formulated an equilibrium relationship between liquid and vapor phases and a moisture flux driven by pore pressure, vapor pressure and temperature gradients. In addition, liquid and interlayer water were measured separately by ethanol in order to reveal each temperature sensitivity in saturation‐humidity paths. Based on the experiments, a modified hysteresis model for moisture isotherm was proposed. Verifications with experimental data showed that the proposed method can simulate moisture behaviors under various temperature conditions. 相似文献
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芝麻粕中芝麻素提取工艺研究 总被引:2,自引:0,他引:2
以料液比、提取时间、提取温度、乙醇浓度为考察因素,采用单因素实验及正交实验对芝麻饼粕中芝麻素进行提取条件优化的试验。得到的最佳条件为提取时间2 h,提取温度55℃,乙醇浓度93%,料液比1∶6.5(mL/g)。 相似文献
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采用激光诱导荧光(LIF)观测方法考察了在气相中分别添加乙醇和二氯甲烷分别对CO2在水中溶解过程界面对流的影响,得到了液相中CO2浓度分布及其演化的观测结果,通过物料衡算得到了相应条件下的液相传质系数。CO2溶解过程会出现由密度梯度引起的Rayleigh对流。实验结果表明,当添加的乙醇含量小于8.47 mg·L-1时,Rayleigh对流会被增强,进而促进了CO2的溶解;随着气相中乙醇含量的增大,Rayleigh对流反而被抑制;气相添加二氯甲烷会显著增强Rayleigh对流,提高了CO2的传质速率,随着气相二氯甲烷含量的增大,CO2在水中溶解过程的液相传质系数呈现先加强后恒定的趋势。 相似文献
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采用索氏提取法提取水浸预处理后的五味子中的木脂素,考察了虹吸次数、液固比、颗粒粒径及乙醇浓度对萃取率的影响,采用响应面法进行优化. 结果表明,五味子醇甲的最佳提取条件为:乙醇浓度98.05%(j),液固比67.20 mL/g,颗粒平均粒度0.33 mm,该条件下理论萃取率为80.90%,实际萃取率为77.17%;五味子甲素的最佳提取条件为:乙醇浓度96.38%(j),液固比72.52 mL/g,颗粒平均粒度0.21 mm,该条件下五味子甲素理论萃取率为77.11%,实际萃取率为74.31%;五味子乙素的提取最佳条件为:乙醇浓度96.38%(j),液固比72.52 mL/g,颗粒平均粒度0.21 mm,该条件下理论萃取率为77.13%,实际萃取率为74.23%. 各因素对木脂素提取率影响的显著性顺序为乙醇浓度>液固比>颗粒粒径. 相似文献
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《The Journal of Supercritical Fluids》2008,44(3):460-468
A recently developed method of falling-weight viscometry was employed to determine the experimental viscosities of the gas-expanded liquid system of ethanol and carbon dioxide at saturation. By adding carbon dioxide into an isochoric system containing metered amounts of ethanol, carbon dioxide concentrations within the gas-expanded liquid system were systematically varied between 0.15 and 0.80 mole fraction in 0.05 increments at constant system temperatures of 25, 30, 35 and 40 °C. Similar to the gas-expanded liquid system of methanol and carbon dioxide, an increase in carbon dioxide concentration in the liquid phase, liquid volume expansion, liquid density and system pressure resulted in a decrease in liquid phase viscosity. The significance of system temperature however, is more apparent with the gas-expanded liquid system of ethanol and carbon dioxide when compared to the gas-expanded liquid system of methanol and carbon dioxide. At equal compositions but varying system temperatures, not only is the viscosity of the ethanol and carbon dioxide system affected to a greater extent, the point at which viscosity reduction is insignificant with an increase in carbon dioxide composition occurs earlier with increasing system temperatures. The estimation of liquid phase viscosities of gas-expanded liquid systems is therefore difficult without experimental data. 相似文献
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考察离子液体溴化-1-乙基-3-甲基咪唑([emim]Br)作为提取溶剂对中草药中白桦脂酸衍生物的提取特性,并找到最佳提取条件。以中草药皂角刺为原料,以离子液体溴化-1-乙基-3-甲基咪唑为提取溶剂,选取提取温度、提取时间和液固比3个因素,进行正交试验,考察提取得率,并与乙醇回流提取方式作对比,找到离子液体提取最佳条件。结果表明:乙醇回流提取对目标成分的提取得率为0.050%,离子液体溴化-1-乙基-3-甲基咪唑在不同条件下对目标成分的提取得率为0.079%—0.107%。在室温(25℃)、液固比30∶1、提取时间2 h的条件下离子液体对目标成分的提取得率为0.105%。离子液体溴化-1-乙基-3-甲基咪唑对中草药皂角刺中白桦脂酸衍生物的提取得率明显高于乙醇回流提取方式的提取得率,最佳提取条件为室温(25℃)、液固比30∶1,提取时间2h。 相似文献
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Robert F. DeJaco Matheus Dorneles de Mello Huong Giang T. Nguyen Mi Young Jeon Roger D. van Zee Michael Tsapatsis Joern Ilja Siepmann 《American Institute of Chemical Engineers》2020,66(4):e16868
In this work, batch-adsorption experiments and molecular simulations are employed to probe the adsorption of binary mixtures containing ethanol or a linear alkane-1,n-diol solvated in water or ethanol onto silicalite-1. Since the batch-adsorption experiments require an additional relationship to determine the amount of solute (and solvent) adsorbed, as only the bulk liquid reservoir can be probed directly, molecular simulations are used to provide a relationship between solute and solvent adsorption for input to the experimental bulk measurements. The combination of bulk experimental measurements and simulated solute–solvent relationship yields solvent and solute loadings that are self-consistent with simulation alone, and allow for an assessment of the various assumptions made in the literature. At low solution concentrations, the solute loading calculated is independent of the assumption made. At high concentrations, a negligent choice of assumption can lead to systematic overestimation or underestimation of calculated solute loading. 相似文献
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Determination of Vapor Pressures for Binary and Ternary Mixtures Containing Ionic Liquid 1-propyl-3-methylimidazolium Bromide 总被引:1,自引:0,他引:1 下载免费PDF全文
Vapor pressure values of binary systems water + ethanol, water + ionic liquid 1-propyl-3-methylimidazolium bromide ([PMIM][Br]), ethanol + [PMIM][Br] and ternary system water + ethanol + [PMIM][Br] at different temperatures were measured by using a modified boiling point method in various concentrations of (16.66%, 33.7%), (17.4%, 33.9%) and (16.5%, 32%) mass percent of ionic liquid, respectively. The experimental vapor pressures of solvent were well correlated by the Antoine-type equation, and the overall average absolute deviation (AAD) was found to be 0.39%. The experimental results for mixtures containing ionic liquid indicate that the vapor pressure of the solvents can be decreased noticeably to different extent due to the affinity difference between ionic liquid and solvent, which is similar to the salt effect of common inorganic salts. As a result, ionic liquid may find industrial applications in extractive distillations for the system with a low separation factor or even for an azeotropic mixture. 相似文献