共查询到19条相似文献,搜索用时 109 毫秒
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利用吸附等温线获得动力学参数,建立了CFD模型,模拟了氢气/氮气在结构化5A分子筛吸附床中的吸附过程,研究了吸附剂层片间距、吸附剂厚度等结构参数和吸附压力、进气流量等工艺参数对混合气吸附效果的影响。结果表明:减小层片间距和吸附剂厚度可显著提高传质系数和床层利用率。增大吸附压力可提高床层利用率,但会减小传质系数。进气流量对传质系数的影响不明显,但当流量较大时,吸附容量和床层利用率均呈减小趋势。结构化5A分子筛吸附剂吸附性能良好。 相似文献
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本文提出液相色谱技术测定吸附相平衡常数和传质系数参数的估值模型,测定蔗糖还原糖在碱土金属型的CR型吸附剂上的吸附相平衡常数和总传质系数。结果表明:吸附相平衡常数随温度的升高而下降,吸附剂的选择性也随之下降;液固相间的总传质系数随温度的升高而增大,并随流速的增大而增大。在三种CR型吸附剂中,CR-2型吸附剂有较好的传质动力学性能和对还原糖吸附有较大的选择性。 相似文献
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吸附法回收废水中柠檬酸的动力学研究 总被引:2,自引:0,他引:2
本文对采用吸附法回收柠檬酸的吸附剂、吸附相平衡和吸附动力学进行系统研究。用间歇法测定柠檬酸在选定吸附剂上,不同温度下的吸附等温线国;用微分床法同时测定其膜传质系数和有效表面扩散系数。得出膜传质系数、有效表面扩散系数和相平衡系数的关联式。判别本研究系统为内、外扩散联合控制。 相似文献
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利用水-空气系统对并流旋转床的气相压降进行了研究,并与逆流旋转床气相压降进行了对比。研究结果表明:并流较逆流旋转床的气相压降低;并流旋转床的气相压降随气体流量的增大而增大,随液体流量的增大而减小,随转速的增大明显降低;而逆流旋转床的气相压降随转速的增大明显升高。利用水吸收SO2的实验对并流旋转床的传质特性进行了研究。研究结果表明:并流旋转床填料层内各点的体积传质系数随着气体流量、液体流量和转速的增大而增大;填料层半径由70mm增大至90mm时,并流旋转床的体积传质系数迅速增大,而后并流旋转床的体积传质系数随半径的增大而减小。对并流和逆流旋转床填料层内体积传质系数进行了对比。结果表明:填料层半径由70mm增大至130mm时,并流旋转床的体积传质系数较逆流时大;当半径大于130mm后,逆流旋转床的体积传质系数大于并流旋转床的体积传质系数,且随半径增大而增大。根据研究结果,提出了降低系统压降的设想,即并流与逆流旋转床串联操作。 相似文献
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利用Aspen Adsorption模拟氯化氢吸附脱微量水过程。通过吸附平衡试验数据估算吸附等温线的常数项,用简化的单塔模型进行了穿透曲线的模拟,得到吸附塔内空隙中水的浓度分布以及塔内吸附剂的吸附量随时间的变化情况,可以看到传质区在轴方向上移动;进一步研究了传质系数和操作压力的变化对穿透曲线的影响,变化趋势与文献报道一致。 相似文献
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《化工进展》2017,(8)
为对抗全球变暖并控制CO_2排放,针对超低浓度气氛中CO_2吸附速率慢、动力学性能差等问题,基于湿法再生技术,系统分析了湿法再生技术中CO_2吸附动力学若干影响因素。通过实验分析与理论模型相结合的方法,研究结构参数、温度及湿度对CO_2吸附的多重影响机制。采用相转化法制备CO_2吸附薄膜,并通过优化及筛选,获得界面结构可控、官能团可调的异相吸附多孔薄膜,实现了CO_2的可逆吸附。针对异相结构吸附剂吸附CO_2过程中传质步骤复杂,描述困难的问题,对传统的缩核模型进行改进,用来描述CO_2吸附反应过程,得到CO_2吸附过程中各部分阻力大小,同时试验获得了结构参数、温度、湿度等对总传质系数及单个步骤(扩散和反应)传质系数的影响规律。结果表明CO_2吸附过程中产物层扩散阻力所占份额较大,而膜扩散阻力所占份额较小,表明下一步吸附剂的优化应重点降低产物层扩散阻力。 相似文献
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Rotary desiccant wheels are widely used in dehumidification and energy recovery applications. In this work, we have developed a 2D, steady state model of a rotary desiccant wheel. Mass and energy balance equations for the air streams and the desiccant wheels were developed. The hydraulic diameter and surface area for heat and mass transfer were calculated based on knowledge of the flute geometry. Appropriate correlations for the Sherwood number and Nusselt number were used to estimate heat and mass transfer coefficients. The model is capable of predicting steady state behavior of desiccant wheels having at the most three sections (process, purge, and regeneration). The mathematical model was validated using a real desiccant wheel, and the calculation results are in reasonable agreement with the experimental data. Based on this model, the temperature and humidity profiles in the wheel during both the dehumidification and the regeneration processes are analyzed. The simulated results were used to gain an insight into the operation of desiccant wheels. The model and the presented results will be useful for optimizing dehumidification and energy recovery applications. 相似文献
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基于热质传递解耦特性的溶液除湿过程传热传质系数(Ⅰ)模型与Le-hD分离测量法 总被引:1,自引:0,他引:1
溶液除湿过程是溶液除湿空调系统中的一个非常重要的耦合传热传质过程。本文对填料塔结构的溶液除湿器建立了一种NTU-Le模型,并基于此模型得到了溶液除湿过程传热传质特性——Lewis数对空气出口含湿量基本无影响,提出一种溶液除湿耦合热质传递过程的热质传递解耦方法——Le -hD分离测量法,来测定溶液除湿过程的耦合传热传质系数。 相似文献
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低温吸湿复合吸附剂的制备及吸湿性能 总被引:1,自引:0,他引:1
针对冷库结霜严重制约其经济性的问题,化学固体吸附除湿防霜技术逐渐得到重视。本文将对水吸附能力较强的金属卤化物与容易定型且传热传质性能较好的分子筛相结合,制成复合吸附剂,建立了低温情况下吸附材料的吸湿性能测试系统,并进行了大量测试,给出了多种材料在-5℃、-10℃、-15℃下的吸湿量及吸湿速率变化,实验结果表明复合吸附剂的吸附性能与单纯的分子筛相比有了明显的改善,13X型分子筛浸渍浓度20%的Na Br溶液所得试样吸湿量和吸湿速率性能优越,复合过程中损失较少,成本低,可作为复合吸附剂应用于冷库除湿系统中。 相似文献
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Samples of six different active carbons, representing hemoadsorbents designed for rapid toxin removal during medical hemoperfusion treatment, were investigated in the same experimental conditions in regard to adsorption of four selected markers. Mass transfer rates for salicylate, phenobarbital, opipramol and vitamin B12 were, generally, higher for spherical active carbons from synthetic polymers than for active carbons from natural raw materials. On the other hand, mass transfer coefficient values, averaged over the selected markers for each adsorbent, were similar for all investigated active carbons, in the range between 0.06 and 0.11 cm/min. It is concluded that the applied model of mass transfer and determination of mass transfer coefficients for solutes with different molecular weights yields an insight into mechanism of adsorption on the investigated active carbons. 相似文献
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对采用规整波纹填料结构的溶液除湿器除湿过程进行了实验研究,空气与溶液流型组织形式为叉流,基于Le-hD分离测量法得到空气入口流量、温度、含湿量以及溶液入口质量分数、温度对耦合传质系数的影响,并采用数据回归的方法对传质系数与Lewis数进行拟合,得到该类结构除湿器除湿过程的传质系数与Lewis数的关联式,并进行了74组稳态实验对该关联式进行误差分析与验证,结果表明根据关联式计算得到的进出口参数变化与实验进出口参数变化之间相对误差很小,进出口空气温度变化、含湿量变化误差分别仅在6%、10%以内,进出口溶液温度变化相对误差不超过12%,表明Le-hD分离测量法的准确性和可接受性。 相似文献
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基于热质传递解耦特性的溶液除湿过程传热传质系数(Ⅱ)实验与Le-hD分离测量法应用 总被引:1,自引:1,他引:0
对采用规整波纹填料结构的溶液除湿器除湿过程进行了实验研究,空气与溶液流型组织形式为叉流,基于Le-hD分离测量法得到空气入口流量、温度、含湿量以及溶液入口质量分数、温度对耦合传质系数的影响,并采用数据回归的方法对传质系数与Lewis数进行拟合,得到该类结构除湿器除湿过程的传质系数与Lewis数的关联式,并进行了74组稳态实验对该关联式进行误差分析与验证,结果表明根据关联式计算得到的进出口参数变化与实验进出口参数变化之间相对误差很小,进出口空气温度变化、含湿量变化误差分别仅在6%、10%以内,进出口溶液温度变化相对误差不超过12%,表明Le-hD分离测量法的准确性和可接受性。 相似文献
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通过研磨将多壁碳纳米管分别与质量分数为30%、40%和50%的无水氯化镁复合,制备了3种不同配比的复合吸附剂MWCNT/MgCl2。采用数字化扫描电子显微镜(SEM)观察复合吸附剂表面材质的结构样貌,通过Hot Disk热常数分析仪测得复合吸附剂的热导率,使用恒温恒湿箱选取具有代表性的温湿度,测试复合吸附剂在不同工况下的水蒸气吸附性能,并采用准二级动力学模型对25℃、50% RH工况下的实验数据进行拟合,应用Autosorb-IQ全自动气体分析仪测试了三种样品在25℃下的等温吸湿曲线。实验结果表明,相同温湿度工况下,随着氯化镁含量增加,复合吸附剂的吸附量提高,25℃、50% RH下氯化镁含量为30%、40%和50%的复合吸附剂M1、M2和M3的吸附量分别为0.62、0.79和0.94 g/g;恒定湿度为50% RH,温度变化为15~35℃时,复合吸附剂吸附量受温度和饱和水蒸气分压力的双重影响,表现为先增加后减小;温度固定为25℃,相对湿度从50% RH增加到80% RH时,复合吸附剂吸附量均大大提升;复合吸附剂在35℃、25% RH中高温、低湿条件下仍表现出较好的吸附能力;在相对压力P/P0为0.3时,M1、M2和M3的吸附量分别为0.24、0.25和0.30 g/g,随着吸附压力的增加,复合吸附剂的吸附量也不断提升,最大吸附量分别达到3.54、3.75和4.42 g/g。复合吸附剂MWCNT/MgCl2的制备研究,为吸附剂的性能研究提供了基础,对太阳能吸附式空气取水的研究具有潜在意义。 相似文献
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Jyotsna Goel K Kadirvelu Chitra Rajagopal Vinod Kumar Garg 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(4):469-476
Recently a new form of activated carbon has appeared: carbon aerogel (CA). Its use for the removal of inorganic (and especially metal ions) has not been studied. In the present study, the adsorption of three metal ions, Hg(II), Pb(II) and Ni(II), onto carbon aerogel has been investigated. Batch experiments were carried out to assess adsorption equilibria and kinetic behaviour of heavy metal ions by varying parameters such as agitation time, metal ions' concentration, adsorbent dose and pH. They facilitated the computation of kinetic parameters and maximum metal ion adsorption capacities. Increasing the initial solution pH (2–10) and carbon concentration (50–500 mg per 50 cm3) increases the removal of all three metal ions. A decrease of equilibrium pH with an increase of metal ion concentration led us to propose an adsorption mechanism by ion exchange between metal cations and H+ at the carbon aerogel surface. Carboxylic groups are especially involved in this adsorption mechanism. Langmuir and Freundlich isotherm models were used to analyse the experimental data of carbon aerogel. The thermodynamics of the metal adsorption was also investigated for the practical implementation of the adsorbent. The sorption showed significant increase with increase of temperature. Kinetics models describing the adsorption of Hg(II), Pb(II) and Ni(II) ions onto carbon aerogel have been compared. Kinetics models evaluated include the pseudo‐first order and second order model. The parameters of the adsorption rate constants have been determined and the effectiveness of each model assessed. The result obtained showed that the pseudo‐second order kinetic model correlated well with the experimental data and better than the pseudo‐first order model examined in the study. Mass transfer coefficients obtained can be useful in designing wastewater treatment systems or in the development of environmental technologies. Copyright © 2005 Society of Chemical Industry 相似文献