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The reaction kinetics of dilute acetic acid with methanol using NKC-9 as catalyst was studied at temperatures of 308 K, 318 K, 323 K, 328 K. The kinetic model based on Langmuir-Hinshel-wood rate model was derived and the activation energy was 6.13×104 kJ/kmol. The experiment of recovery of dilute acetic acid was conducted in a packed bed catalytic distillation column. The optimal process parameters and operational conditions determined to make up to 85.9% conversion of acetic acid are as follows:the height of catalyst bed is 1 100 mm, reflux ratio is 4:1, and the ratio of methanol to acetic acid is 2:1. The method can be used as a guide in industrial scale recovery of 15%-30% dilute acetic acid. 相似文献
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The dissolved oxygen (DO) level in groundwateris a key parameter forin situbioremediation of con-taminated groundwater. However, due to the poorcontent of DO in groundwater, aerobic microbial deg-radation is difficult to occur in natural condition. Ear-ly work on enhancedin situbioremediation deliveredoxygen to the contaminated aquiferbyspargingairin awell, but the low solubility of oxygen increased thedifficulty and expense of maintaining aerobic condi-tions in groundwater[1]. This problem … 相似文献
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A volume-based method for measuring particle-size distribution (PSD) fractal dimensions of porous mediums was developed by employing laser size-analyzing technology. Compared with conventional approaches of using hydrometer or screen to determine PSD, this method can avoid calculation errors and measure smaller size-scale porous medium. In this paper the experimental porous mediums were brown soil, kaolin and sand soil. A micro-order of magnitude ( 10 ^-5 m) in particle-size interval could be shown in PSD results of brown soiland kaolin. The experiments indicated that brown soil had a nearly mono-fractal PSD character, while kaolinand sand soil showed multi-fractal PSD characters. By the adsorption isotherm experiments, the PSD fractal dimensions of the sand soil were also found to keep a linearly increasing relation with the linear adsorptive parameters of the soils in different intervals to adsorb benzene from aqueous solution. 相似文献
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A one-dimensional column is set up to study the mass transfer during air sparging process for methyl tertiary butyl ether(MTBE) removal in saturated soil and groundwater, with the condition of different airflow and soil penetrability. It is shown that the removal rate of MTBE can reach 80%, 90% and 95% when airflow is 0.05 m3/h, 0.085 m3/h and 0.10 m3/h, respectively. Increasing airflow will help to increase the removal rate of dissolved MTBE, but eventually a threshold removal rate is reached, above which further increasing air injection rates does not increase the removal rate. Fine sand allows the injected air to travel in bubble form, while coarse sand and medium sand allow the injected air to travel in the form of discrete channels; the greater the soil grain size is, the more extensive the channel net work forms, which in turn leads to higher removal rate. A tailing effect of lingering residual contaminant concentrations occur within the fine sand. About 20% of MTBE cannot be removed. 相似文献
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CFD Analysis of Gas Distributor in Packed Column--Prediction of Gas Flow and Effect of Tower Internals Geometry Structure 总被引：1，自引：0，他引：1
Computational fluid dynamics (CFD) simulations were carried out on the gas flow patterns of twin-tangential annular deflector gas distributor in the absence of liquid flow in a packed column (6.4 m in diameter), and the gas flow field in the column was presented close to reality on the whole. Furthermore, after ame-lioration of this gas distributor frame, turbulence energy and turbulence energy dissipation rate were both decreased greatly.Simulation results showed that the flow pattern and the distribution of gas flow were strongly affected by the column bottom frame; the proper column bottom frame could decrease the flow pressure drop greatly. Multifold factors, such as the column bottom geometry structure and distributor structure which affects the distribution capacity, must be considered. 相似文献
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A mathematic model of two-phase flow and a physical model of two-dimensional (2D) vertical section for the plate-type structured packing Mellapak 250.Y were set up and verified. The models were used to study the influence of packing’s surface microstructure on the continuity of liquid film and the amount of liquid holdup. Simulation results show that the round corner shape and micro wavy structure are favorable in remaining the continuity of liquid film and increasing the amount of liquid holdup. The appropriate liquid flow rate was determined by investigating different liquid loadings to obtain an unbroken liquid film on the packing surface. The pressure difference between inlet and outlet for gas phase allowed gas and liquid to flow countercurrently in a 2D computational domain. The direction change of gas flow occurred near the phase interface area. 相似文献
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采用新型电沉积 生物膜复合工艺处理含重金属离子 (Cr3 + )有机废水 ,阐述其作用机理 .实验废水中的有机物由生物膜中的复合微生物菌群作为营养源而消耗 ;重金属离子则一部分通过电沉积去除 ,另一部分通过生物膜吸附而去除 ,净化后废水能够达到工业回用水标准 .探讨了培养、驯化后的复合微生物降解有机物动力学速率 ,并将采用复合工艺与单纯的电沉积工艺及生物膜工艺处理含重金属离子有机废水的实验结果进行对比 ,结果表明 ,C6H12 O6含量为 5 0 0mg·L-1及Cr3 + 含量为 10mg·L-1的废水 ,利用复合工艺净化处理后 ,C6H12 O6含量为 2 0— 30mg·L-1,Cr3 + 含量低于 1mg·L-1. 相似文献
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CFD Analysis of Gas Distributor in Packed Column ——Prediction of Gas Flow and Effect of Tower Internals Geometry Structure 总被引：2，自引：0，他引：2
Asoneofinternalparts,thefeedgasdistributorplaysanimportantroleinapackedcolumn.Thesmoothoperationandbetterqualityofproductsaregreatlyinfluencedbyitsperformance,especiallyinthecolumnwithlargediameter,shortpackedbedandlowpressuredrop.Duetotheimpor tanceoftheuniformityofinletgasdistribution ,itisessentialtodesignagoodfeedgasdistributor.However,fewtheoreti calandexperimentalapproacheshavebeencarriedoutinthisareasofarduetothecomplexityofthefluidflow[1 ,2 ] . Theliquidflowstructureisimprovedbyanew… 相似文献
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Characterizations of PSD Fractal of Porous Medium 总被引：1，自引：0，他引：1
Fractalisatermusedtodescribegeometricalobjectsthatareinvariantuponthechangeoflengthscale .Manyfrac talcharactersofscaleinvarianceonporousmediumshavebeeninvestigatedduringthepastdecades[1] .Particle sizedistribution (PSD)isafundamentalpropertyofporousmedi ums.PSDofporousmediumsiscommonlyreportedintermsofthepercentagesofvariousparticle sizeintervalsandhasusuallybeenfoundtoobeypowerscalingofthetype[2 ] N(≥d)∝d-Dp (1)whereN(≥d)isthenumberofparticlediameterlargerthanorequaltod ,andthepow… 相似文献
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钒铬废渣和含重金属氨氮废水是钢铁、有色和电池等涉重行业产生的典型污染物,排放强度大、处理技术缺乏,已严重危害环境并制约相关企业正常发展。“工业钒铬废渣与含重金属氨氮废水资源化关键技术和应用”项目紧密结合重金属和氨氮等重点污染物减排和传统产业绿色化升级的重大社会需求,在国家863、水重大专项、自然科学基金等科技计划资助下,针对我国量大面广的钒铬废渣和含重金属氨氮废水,发明了钒铬伯胺萃取分离、药剂强化热解络合-精馏、钒铬废渣高值化清洁利用与污染控制等多项关键技术,研发了新型伯胺萃取体系,研制了热敏易乳化有机相反萃装备、高效脱氨精馏塔等关键大型设备,集成上述原创性关键技术与设备建成世界首套万吨级钒铬废渣高效清洁利用示范工程和含重金属高浓度氨氮废水资源化与无害化示范工程,并推广到稀土、钼、镍、铌钽、锆等行业,建成稳定可靠的废水处理示范工程20套,源头消除重金属和氨氮污染的同时实现了高值化利用。 相似文献
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