Modeling of the Wall Effect in Packed Bed Adsorption

A model developed for catalytic packed bed reactors and consistently accounting for the influence of the tube wall on porosity, flow and transport phenomena is used in order to simulate the operation of packed bed adsorbers. By comparison of simulation results with reduced versions of the model the influence of the wall on the adsorber performance is worked out and found to be major at low ratios between tube and particle diameter. The interaction between maldistribution, thermal effects and intraparticle resistances in such adsorber tubes is discussed.     

Oxidation of SO2 in a Trickle Bed Reactor Packed with Activated Carbon at Low Liquid Flow Rates

In this study, the oxidation of SO₂ on activated carbon (AcC) by using distilled water and air was carried out in a laboratory scale trickle bed reactor (TBR). Distilled water and air containing 1.7 % (v/v) SO₂ were fed co‐currently downward through a fixed bed of AcC particles in a range of 1–7 cm³/s and 10–27 cm³/s respectively. H₂SO₃/H₂SO₄ solutions were the products obtained in the liquid phase. Steady‐state experiments were performed in a column of 0.15 m packing height and 0.047 m column diameter at 20 °C and atmospheric pressure. Experimental reaction rates of this study were compared with those of other studies on the basis of plug flow model of Mata‐Smith given in literature.     

活性炭纤维填充床脱除水中苯酚及填充床的再生

采用活性炭纤维吸附法净化水中微量的苯酚。在25℃、30℃和35℃下,实验测定活性炭纤维吸附苯酚的吸附平衡等温线,该吸附等温线符合Langmuir型,最大饱和吸附容量达0．26kg(苯酚)／kg(活性炭纤维)在25℃下;0．25kg(苯酚)／kg(活性炭纤维)在30℃下;0．239kg(苯酚)／kg(活性炭纤维)在35℃下。水溶液的pH值将影响吸附容量,在碱性条件下吸附容量显著下降,这将有利于吸附剂的再生。苯酚在活性炭纤维填充床的穿透曲线被测量,在5％突破点处的动态吸附容量为0．14kg(苯酚)／kg(活性炭纤维)在25℃下。采用40℃、5％NaOH溶液再生被苯酚饱和的活性炭纤维填充床,再生后吸附效率达90％以上。     

活性炭吸附法脱除废水中的苯酚及吸附剂再生的研究

对活性炭对废水中苯酚的吸附平衡以及活性炭的再生进行了试验性研究和理论性探讨。结果发现,温度对活性炭的吸附能力有显著的影响,低温地吸附有利,吸附平衡可用Ｌａｒｇｍｕｉｒ方程描述;ＰＨ值对活性炭对苯酚捐附也有较强的影响,酸性的水溶液对吸附有利,强碱性水溶液对再生有利。分别采用乙醇、丙酮、ＮａＯＨ溶液、ＮａＯＨ溶液＋乙醇的混合液对吸附剂活性炭进行再生,再生率均能达到８５％以上,基本满足工业要求。     

活性炭填充床脱除水中苯酚及填充床的再生

实验研究了活性炭填充床脱除水中苯酚的吸附性能,探讨其饱和吸附填充床的再生方法,结果表明当平衡浓度范围为0－0．8kg/m^3时,活性炭对水中苯酚的吸附能力达230kg/kg（吸附剂）,吸附等温线符合Langmuir型,填充床的穿透曲线和穿透时间强烈依赖于实验条件,较高的进料浓度,较大的进料速度,以及较短的床层长度都将使填充床穿透较快;用热的NaOH稀溶液可再生被苯酚饱和的活性炭纤维填充床,再生效率达90％以上。     

Removal of Lead in a Fixed-Bed Column Packed with Activated Carbon and Crab Shell

ABSTRACT

Crab shell particles (Protunus trituberculatus) and activated carbon (Norit 0,8 SUPRA) were used as packing materials in a fixed-bed column. When 1 g crab shell was added in a column packed with 10 g activated carbon, breakthrough occurred at 1500 bed volumes as compared to 380 bed volumes for 10 g activated carbon only. The addition of crab shell particles into an activated carbon column resulted in an increased uptake of lead. The dramatic improvement might be attributed to an increase in and OH^? available for binding lead. From the results of SEM, XRD, and FT-IR analyses, the major mechanism of lead removal was based on dissolution of CaCO₃ in the crab shell followed by precipitation of Pb₃(CO₃)₂(OH)2(s) on the surface of activated carbon. The lead uptake increased twofold when the influent lead concentration was increased from 10 to 50 mg/L.     

填充床中椰壳活性炭负载季铵盐催化CO2连续环加成

将一种季铵盐固定在椰壳活性炭(CSAC)颗粒上,得到负载型季铵盐催化剂,于填充床反应器中无溶剂条件下连续催化CO2与环氧氯丙烷(ECH)环加成反应。采用低温氮气吸附、红外光谱(FTIR)、热重分析、X射线光电子能谱(XPS)测定了催化剂的结构、热性能。考察了压力、温度、反应时间对环加成反应性能的影响。结果表明,在ECH空速为14.1 h-1(WHSV),压力为1.4 MPa,温度为140℃时,ECH转化率为50.3%,氯丙烯碳酸酯(CPC)的选择性大于98%。     

Adsorption Characteristic of Methanol in Activated Carbon Impregnated with Lithium Chloride

The amount of methanol adsorbed in composite sorbents made of activated carbon impregnated with two different mass fractions of LiCl were assessed at selected temperatures and pressures. The adsorbed amounts, temperature, and pressure were well correlated with a Langmuir‐type equation that had the same set of coefficients for different isotherms and isobars. However, sorption hysteresis was observed in the composite sorbent and the main practical implication of this phenomenon was the increase of the regeneration temperature necessary to desorb a certain amount of methanol. The specific cooling capacity and the coefficient of performance of the studied adsorbents were calculated, and it was found that the sorbent with 21.3 wt % of LiCl had specific cooling capacities 11 % to 31 % higher than those obtained with the untreated activated carbon, when the regeneration temperature was 388 K. The heat sink temperature was 303 K, and the evaporation temperature ranged between 263 and 283 K. However, at the same operation conditions, the coefficient of performance of both sorbents was similar.     

旋转床填料中的传质及其模型化

用氮气解吸水中溶解氧,发现了三个在前人研究中未曾提及的重要现象：（１）保持填料外径而扩大内径,平均体积传质系数增大;（２）比表面积大小并不是传质好坏的决定因素;（３）转子填料与旋转床机壳间空腔中液滴表面的传质量,对整个装置中的传质总量,有不可忽略的贡献。据此,建立了基于液体在填料内微粒化,传质同时在填料和液滴表面进行的传质模型。模型计算结果较好地与实验结果吻合,并对上述三个现象作出了合理的解释。     

Removal of Cyanides from Water by Air Oxidation in a Cocurrent Downflow Fixed Bed Reactor

A method for removal of cyanides from water is described. The method involves the air oxidation of cyanides in a fixed bed reactor with cocurrent downflow. Effects of parameters such as temperature, concentration, gas and liquid flow rates on the oxidation yield are studied. It was observed that the yield increases by increasing temperature and decreasing gas and liquid flow rates. Altering the concentration had no clear effect on the yield. A yield of 86 % was achieved at high temperature (60°C) while the maximum yield was 68 % at room temperature.     

旋转填料床中活性炭上间苯二酚的脱附行为及动力学

以旋转填料床为脱附设备,采用准二级动力学模型研究了间苯二酚在活性炭上的脱附行为及动力学,并与传统固定床进行了对比. 结果表明,在温度20℃、液体流量50 L/h、超重力因子32.63及pH值11、脱附剂乙醇40wt%、脱附时间90 min的优化条件下,间苯二酚脱除率达93.90%,比传统固定床提高了58.54%,超重力强化了液固传质,对脱附有利;脱附速率常数随液体流量和超重力因子增大而增大,由以超纯水为脱附剂时的13.27×10?3 g/(mg?min)提高到以乙醇为脱附剂时的25.48×10?3 g/(mg?min).     

蒸馏过程中旋转填料床的传质和流体力学特性

建立了一套完整的精馏实验装置,以甲醇-水溶液为物系,在常压、全回流操作条件下,研究了旋转填料床的传质和流体力学性能. 结果表明,旋转填料床的理论塔板数随超重力因子和气相动能因子的增大出现峰值,理论塔板高度最小为0.0109 m;气相压降随气相动能因子、超重力因子的增大而增大. 在实验基础上应用最小二乘法建立了旋转填料床的传质、压降实验关联式.     

Evaluation of Mass Transfer Coefficients in Biotrickling Filters: Experimental Determination and Comparison to Correlations

Overall mass transfer coefficients (K_Ga and K_La) were determined experimentally for four different‐nature packing materials used in gas‐phase biotrickling filters. A simple methodology based on overall mass balances and following a standard procedure allowed to calculate the mass transfer coefficients under different operating conditions corresponding to usual biotrickling filtration situations. Results showed an increase of mass transfer resistance when increasing the empty bed residence time (EBRT) of the reactor for all packing materials. Experimental results were fitted to existing and well‐accepted correlations used in conventional biofilter or biotrickling filter modeling. The comparison of experimental and theoretical data showed huge discrepancies. Simple correlations for the experimental data obtained in this study were also suggested.     

活性炭吸附甲基橙模拟废水预测模型研究

分别采用BP人工神经网络算法及多元线性回归法,以实验所得的36组数据为样本,建立了以吸附时间、活性炭投加量及甲基橙废水浓度为输入变量,以活性炭吸附处理后甲基橙溶液的吸光度为输出变量的吸附预测模型,并进行了两模型预测效果的对比。结果表明,BP神经网络模型获得了比多元线性回归更好的拟合预测效果。使用BP神经网络模型可以实现同时考虑三个操作因素条件下活性炭吸附特性的预测,而且预测结果与实验数据吻合度较高,其预测样本最大和最小相对偏差分别为2.92%和0.029%,残差绝对值小于0.050 5。     

醋酸丁酯在活性炭纤维床层中的穿透曲线

研究了醋酸丁酯在活性炭纤维床层中的吸附过程 ,获得吸附速率方程和 Freundlich吸附等温方程的吸附级数、吸附平衡常数。将吸附速率方程、吸附等温方程与物料衡算相结合预测了其他条件下的穿透曲线。预测曲线与实验结果符合得较好。     

填料塔中的NaOH水溶液脱除空气中微量CO2的传质动力学

在填料吸收塔中测定了25℃时NaOH水溶液吸收空气中微量CO2的体积传质总系数(KGαv)．并研究了进口气体中CO2的含量、气体流量、吸收液喷淋密度以及NaOH浓度对体积传质总系数的影响。进口气体中CO2的含量、气体流量、吸收液喷淋密度对KGαv的影响较小;NaOH浓度对KGαv的影响较大,随着NaOH浓度的增加,KGαv显著提高。     

汽油饱和蒸气吸附用活性炭的制备

以煤为原料,KOH为活化剂制备活性炭。建立了静态吸附装置,并通过该装置研究了90#汽油在不同活性炭样品上的吸附性能。在制备过程中,考察了碱炭比、活化温度、活化时间对活性炭吸脱附性能的影响。研究发现,常温常压下活性炭对汽油饱和蒸气的吸附性能受多个参数的影响,其中BET比表面积影响最大,另外较大的孔、较宽的孔径分布,有利于脱附。同时得到最优的制备条件,碱炭比为5：1、活化温度800℃、活化时间1h。     

错流旋转填料床传质特性影响因素的实验研究

采用CO2-NaOH体系,在中试规模的实验装置上进行传质实验,考察了气速、液体喷淋密度、超重力因子、气液接触时间对错流旋转填料床的总体积传质系数KLa及有效传质比表面积ae的影响. 结果表明,KLa和ae均随气速、液体喷淋密度和超重力因子增加而增大,KLa随气液接触时间增加先缓慢增大后急剧下降,ae则随气液接触时间增加而缓慢下降. 最佳操作条件为：气速1.69 m/s,液体喷淋密度32 m3/(m2×h),超重力因子104,气液接触时间0.1 s. 错流旋转填料床在处理大气量气体时传质效果增强,是同类文献错报道的1.52~2.32倍. 对各操作参数下所得实验数据进行回归,得关联式KLa=1.8221(atDL/dp)ReL0.6371GrL0.0548ScL0.0623和ae/at=2980.9ReL0.2349FrL-0.045WeL0.5023f-0.5.     

超重力反应器中甘氨酸钠吸收混合气体中CO_2的实验研究

CO2减排已经成为国际关注的热点问题。近年来,化学吸收法以其效率高、适应范围广、技术成熟等优点,逐渐占据主导地位。采用甘氨酸钠溶液为吸收剂,在超重力反应器中进行了CO2吸收实验,考察了转速、吸收液温度、吸收液浓度、气液比等对CO2吸收率的影响。结果表明:CO2的吸收率随着转速的增加而上升,当转速达到1000 r?min?1后,吸收率基本趋于稳定;CO2的吸收率随着吸收液温度的升高而升高,在90℃时可以达到83%以上;在实验范围内,CO2的吸收率随吸收液浓度的增加略有增加,随气液比的增加而逐渐降低并趋于稳定。     

活性炭催化剂臭氧催化氧化处理废水的研究进展

介绍了近年来国内外活性炭催化剂臭氧催化氧化的研究结果,对活性炭及金属负载型活性炭催化剂的反应机理进行了总结。讨论了非均相臭氧催化氧化过程中活性炭的主要作用,活性炭催化剂的表面物化性质、pH值、温度在臭氧催化氧化过程中的影响规律。并提出活性炭催化剂的降解机理以及催化剂性质与有机污染物的化学结构之间的关系还需要进一步的研究。