A Novel Continuous Rotating Annular Liquid Chromatograph with a Multichannel Peristaltic Pump for Variable Eluent Withdrawal

Abstract

A novel continuous rotating annular chromatograph is proposed and used for the separation of amino acids. The system is equipped with a multichannel peristaltic pump to withdraw the eluent and to easily regulate its flow rate. The inlet of the annular chromatographic packed bed is divided into a number of chambers to prevent circumferential dispersion of the sample. The mass transfer characteristics of the apparatus were theoretically analyzed by using a two-dimensional transport model. The experimental results for solute elution are well simulated by the transport model. Solute dispersion in the annular column was found to be negligible. A shallower liquid depth in the inlet chamber gave sharper concentration peaks. An increase in the number of feed nozzles and the installation of inlet chambers were found to be preferable for multicomponent separation.     

直接精馏法提取纤维素乙醇

采用直接精馏法研究了高固含量(质量分数)、高黏度的玉米秸秆发酵醪液的精馏工艺,设计了带搅拌桨的不锈钢筛板-填料精馏塔,确定了固含量为11.56%的发酵醪液的幂律模型本构方程,进而得到塔釜中发酵醪液的黏度和搅拌桨转速的关系。在进料量为2.7 L/h、进料体积分数为10%左右、进料温度为30℃、操作压力为常压的条件下,考察了进料位置、回流比、搅拌桨转速等操作条件对纤维素乙醇精馏的影响。实验结果表明:第27块塔板进料、操作回流比5.0、搅拌桨转速36 r/min为最佳操作条件,塔顶乙醇收率可达到99%以上。     

Aerodynamics of a novel rotating jet spouted bed

A novel rotating jet spouted bed (RJSB) is developed and tested. It consists of a rotating air distributor with two radially located spouting air nozzles. The effects of bed height, distributor rotational speed, nozzle diameter and particle properties on the flow characteristics were examined. Various flow regimes were mapped as functions of distributor rotational speed and superficial air velocity for different materials and column dimensions. Empirical correlations were developed for the minimum spouting velocity, peak pressure drop and steady spouting pressure drop.     

Continuous Separation of Fructooligosaccharides Using an Annular Chromatograph

Abstract

A continuous rotating annular chromatograph with a rotating feed nozzle and product collectors was used to separate mixtures of fructooligosaccharides. Oligosaccharides could be continuously separated from monosaccharides and a disaccharide to obtain a lower calorie sweetener. Analytical solutions agreed well with experimental results.     

Continuous Separation of Carbohydrates by Ion-Exchange Chromatography

Abstract

A synthetic mixture of fructose, mannitol and sorbitol was continuously separated by a chromatographic method using a cation-exchange resin (Dowex 50W-X8) in its Ca²⁺-form as the stationary phase. An annular chromatograph (AC) was used to achieve a continuous mode of operation. Distribution and mass transfer coefficients of the three substances as well as bed properties were obtained by batch chromatography. The separation was simulated mathematically in terms of an approximate linear chromatographic theory was applied to the modeling of the behavior of the continuous separations. The influence of rotation rate, column loading, eluent flow rate and feed concentration on the resolution of the individual peaks were investigated.     

Extraction of Caffeine with Annular Centrifugal Contactors

Abstract

An extraction process for caffeine has been developed with annular centrifugal contactors. The caffeine distribution ratio in the mother solution effluent‐chloroform system was measured to be about 18.6. Both the pilot tests and the plant tests have been completed with Φ20 mm and Φ230 mm annular centrifugal contactors, respectively. The extraction rate higher than 99% was achieved in the pilot tests, when the rotor speed was 3000‐4500 r/min, the total flow was 20‐80 mL/min, and the flow ratio (A/O) was 2/1. When the rotor speed was 1800 r/min, the mother solution flow was 2000 L/h, and the chloroform flow was 1000 L/h; the extraction rate was also more than 99% in the plant tests.     

改进的Scheibel萃取塔的性能研究

Scheibel萃取塔是一种常用的多级逆流搅拌萃取装置,它的主要缺点是存在比较严重的返混。为了减少返混,提高Scheibel萃取塔的萃取效率,本文设计了一种改进的Scheibel萃取塔,在传统的Scheibel萃取塔的填料两端各添加一块筛板,这样可以降低返混,减少转动流体对分层段的影响。本文用丙醇-水-庚烷体系研究了开孔率,搅拌速度,进料流量对改进的一级Scheibel萃取塔萃取效率的影响。得到了较佳的筛板开孔率10%和较佳的操作条件。在较佳的筛板开孔率和操作条件下用改进的三级Scheibel萃取塔和传统的三级Scheibel萃取塔进行萃取效率的对比,结果显示改进的Scheibel萃取塔的萃取效率要远好于传统的Scheibel萃取塔。     

A High-Capacity Pressurized Continuous Chromatograph

Abstract

Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. The feed material is continuously introduced at a stationary point at the top of the bed, and eluent is allowed to flow everywhere else around the annulus. The rotation of the sorbent bed causes the separated components to appear as helical bands, each of which has a characteristic, stationary exit point; hence the separation process is truly continuous.

The concept has been developed primarily on a 279-mm-diam by 0.6-m-long device with a 12.7-mm-wide annulus. The effects of annulus width and diameter have been studied using the same device with annulus widths up to 114.3 mm. With this largest width, approximately 96% of the area available within the outer cylinder is devoted to the rotating sorbent bed. Further annulus-width studies have been pursued on units with 89- and 445-mm diameters. These geometric extensions to the basic concept allow extremely large capacity increases with minimal loss in separation and no increase in chromatograph diameter.

The effects associated with increased feed concentration have also been studied. In this effort as well as in the annulus-width program, the separation of copper, nickel, and cobalt components from a carbonate solution was studied in detail. The nickel and cobalt components are found in the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Nominally 50-μm-diam Dowex 50W-X8 cation exchange resin was used     

离子交换树脂吸附古龙酸的工艺

应用自行合成的阴离子树脂D02直接吸附发酵液中的2-酮基-L-古龙酸,并研究了其吸附的静态与动态过程.利用Langmuir和Freundlich吸附等温线方程对吸附等温线数据进行拟合,发现2种模型相关性都很好.测定了不同流速、温度、浓度以及pH条件下古龙酸在合成树脂柱中的穿透曲线,当上柱液pH为1.5、质量浓度为10 g/L、吸附温度为309 K、流速为0.35 mL/min时,每g湿树脂的动态附容量为133 mg.同时测定了不同洗脱剂、洗脱流速条件下的洗脱曲线.每g湿树脂的动态吸附容量达到了133 mg,当温度为283 K、洗脱剂为10%H2SO4-CH3OH、流速为0.2 mL/min时,洗脱收率可达65.3%.     

Continuous annular chromatography for the separation of beet molasses

The continuous separation of a multicomponent feedstock on a rotating annular chromatograph is described. The annulus width was 12 mm, diameter 300 mm and height 1400 mm. The annulus was packed with a 420 micron ion-exchange resin in the sodium form. The feedstock separated was beet molasses which is the final syrup spun off after repeated crystallisations in the extraction of sugar. Two basic mechanisms were in operation to separate sucrose from impurities: ion exclusion and molecular sieving. A statistical approach was made to set up an experimental programme and analyse the results. Four factors were studied: feed flowrate, feed concentration, annulus rotation rate and eluent rate. Two of these, namely feed rate and eluent rate, significantly affected the response. The response was the separation achieved using the annular chromatograph between the sucrose and non-sucrose solids. A further series of experiments demonstrated the practical considerations to be made when separating beet molasses. A crystallisable product sucrose rate of 207 gh^?1 was achieved.     

Preconcentration of Heavy Metals and Matrix Elimination using Silica Gel Chemically Modified with 2,3‐Dihydroxybenzaldehyde

Abstract

Many direct methods cannot easily be used to measure analytes such as Cd(II), Cu(II), Ni(II), Pb(II), and Zn(II) ions in sea and river water since these elements are present at very low concentration and the sample has a very complex matrix. In this study a method was developed to preconcentrate these ions by solid phase extraction within a column system using a newly synthesised 2,3‐dihydroxy benzaldehyde modified silica gel (SGDHB). Different parameters, such as pH, resin amount, eluent type, eluent volume, sample flow rate, preconcentration factors, and resin capacity were determined for the preconcentration of metal ions with the resin. Samples (125–500 ml) containing metal ions were passed through the column filled with SGDHB resin so that metal ions were retained on the column. The preconcentrated analytes were then eluted with 15 mL of 0.1 M HCl. The metal concentrations in the eluate were measured by FAAS. A sample and eluent flow rate of 1.12 and 0.56 ml/min respectively was used. Estimates of accuracy, precision, and detection limits were determined. In addition, analysis of the CRM LGC 6156 harbor sediment was undertaken, using the resin to isolate the analytes from potential interferences. Good agreement with certified values was obtained, indicating that the method is equally applicable to the analysis of water samples and to digests of solid materials.     

A rotating annular chromatograph for continuous separations

Preparative, multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular sorbent bed with fixed multiple feed points and fixed product withdrawal locations. The cation exchange separation of copper, nickel, and two cobalt complexes has been extensively used to study the effects of rotation rate, eluent rate, bed loading, and column size on separation performance. Experimental results have been compared with three theoretical models: plate theory, an analytical solution which incorporates multicomponent Langmuir isotherms, and an extension of the analytical solution to include dispersion effects.     

Continuous chromatographic separation of fructose, mannitol and sorbitol

The separation of mixtures of fructose, mannitol and sorbitol by continuous annular chromatography on Dowex 50W-X8 has been investigated. Distribution and mass transfer coefficients of the three substances were obtained by batch chromatography. The influence of feed concentration and flow rate on these parameters were discussed. The separation was simulated numerically and compared with experimental data. With this procedure, the separation of mixtures of fructose, mannitol and sorbitol by continuous annular chromatography (CAC) was calculated in advance, using only batch data. Additionally, the influence of rotation rate, column loading, eluent flow rate and feed concentration on the resolution of the individual peaks were investigated. With these results, the operation parameters for an industrial application of the CAC for this separation problem were determined.     

Modeling and Simulation of Continuous Rotating Annular Ion-Exchange Chromatography for Separation of Amino Acids

Abstract

Separation of an amino acid mixture using continuous rotating annular ion-exchange chromatography is numerically simulated by a newly constructed mathematical model. Dissociation reactions of amino acids and eluent buffer components, Nernst-Planck-type intraparticle ionic transport, and a nonlinear ion-exchange equilibrium based on ion-exchange selectivity are considered in the model. The simulated and the experimental results agree well under various operation conditions. The effects of rotation speed of the annular bed and the interstitial liquid velocity on separation are studied experimentally and theoretically.     

利用分子蒸馏技术提取玫瑰油的工艺研究

玫瑰鲜花用有机溶剂萃取后,利用分子蒸馏技术可以从中提取出香气纯正、色泽清亮的玫瑰精油,出油率达到万分之十。用分子蒸馏技术处理浓缩液时,应先脱除低分子物质。条件为进料温度40℃、系统真空度10-20Pa、柱温度45-50℃、刮膜机转速200-250r／min、蒸馏速度1mL／min;然后再脱除高分子物质,条件为进料温度60℃、冷却温度25℃、系统真空度1Pa、蒸馏温度120-125℃、刮膜机转速300-350r／min、蒸馏速度1mL／min。     

Fixed bed and reduced lumped diffusion model parameter estimation of copper biosorption using Aspergillus niger biomass

In this study, fixed bed model and reduced lumped diffusion model were used to explain biosorption behaviour of Cu (II) in a continuous column of Aspergillus niger biomass. The breakthrough time was evaluated for both models as a function of influent flow rate and bed height for a feed solution at 10 mg/L metal ion concentration and compared with experimental results. MATLAB was used to solve the partial differential equations and breakthrough curve was plotted. The breakthrough time obtained experimentally was comparable with data evaluated by these models. It was observed that fixed bed model and reduced lumped diffusion model can predict column dynamics more accurately at high flow rate, that is, at 9.8 mL/min for all (2.1, 3.1, and 4.1 cm) bed heights. © 2011 Canadian Society for Chemical Engineering     

Concentration and Drying of Tea Polyphenols Extracted from Green Tea Using Molecular Distillation and Spray Drying

The purpose of this study was to develop a method of combining molecular distillation and spray drying to concentrate and dry tea polyphenols extracts. Molecular distillation and spray drying of tea phenols extracts were performed using an orthogonal array design. The order of importance that influenced molecular distillation was distillation temperature > flux > rotational speed. The optimal conditions for concentration by molecular distillation were 70°C distillation temperature, 10 mL/min flux, and 1,200 n/min rotational speed. Inlet temperature was found to be the most important determinant of spray drying. The order of importance that influenced the spray drying was inlet temperature > feed flux > wind capacity > feed concentration. The optimal conditions for drying of tea polyphenols extracts by spray drying were determined as follows: 170°C distillation temperature, 3 mL/min feed flux, 30% feed concentration, and 30 m³/h wind capacity. Results of this study indicated that the combination of molecular distillation and spray drying was very suitable for the concentration and drying of tea polyphenols extracts. Using this approach to process tea polyphenol extracts can not only maintain the quality of tea polyphenols but also save time and energy.     

Extraction of Hydrocortisone from the Fermentation Liquor with Annular Centrifugal Contactors

Abstract

A continuous countercurrent extraction process for the recovery of hydrocortisone from the fermentation liquor has been developed with annular centrifugal contactors. When the hydrocortisone was extracted from the fermentation liquor with the butyl acetate, the distribution ratio increased with increase of the hydrocortisone concentration in the equilibrium aqueous phase. Both the laboratory tests and the plant tests have been finished with Φ20 mm and Φ230 mm annular centrifugal contactors respectively. In the laboratory tests, when the rotor speed was 3400～4200 r/min, the fermentation liquor flow was 30～50 mL/min and the phase ratio (V_O/V_A) was 0.36～0.50, the percent recovery of hydrocortisone was higher than 92%. In the plant tests, when the rotor speed was 2000 r/min, the fermentation liquor flow was 2000 L/h and the butyl acetate flow was 1000 L/h, the percent recovery of hydrocortisone was about 96.5～98%.     

新型径向叶片式旋转床压降分析及气相流场模拟

针对折流式旋转床压降高、能耗大的问题,提出了一种新型超重力旋转床设备--径向叶片式旋转床。首先,对该旋转床的压降进行了理论分析和建模,并利用水-空气体系进行了实验研究。通过改变气量、转速和液量探究了新型径向叶片式旋转床压降的变化规律,结果表明压降随气量、转速和液量的增加而增加,且随着气量和转速的增加,液量对压降的贡献逐渐减小。压降模型的预测值与实验数据的相对偏差基本在10%以内,表明模型可以较好地预测新型径向叶片式旋转床的压降。另外,通过计算流体力学（CFD）软件的模拟获得了旋转床内气相流场和压力分布的结果,发现转子内压降是总压降的主要部分;气体进入转子后会因叶片作用使得周向速度变大,并在转子外缘处达到最大值;气体的进口流速将会影响旋转床内的气相分布。利用实验数据对CFD模拟结果进行了验证,两者的相对偏差在10%左右。     

Liquid holdup and wetting efficiency in a rotating trickle-bed reactor

A rotating trickle-bed reactor (RTBR), having the advantage of mass transfer enhancement of 1–3 orders of magnitude higher than a packed column reactor, can intensify the apparent reaction rate of gas–liquid–solid catalytic reactions. However, studies of hydrodynamics like liquid holdup and wetting efficiency, which are essential for the RTBR design, are scarce. In this work, we have systematically, for the first time, investigated the liquid holdup and wetting efficiency in a RTBR packed with alumina spheres. The quantitative results revealed that the rotation reduced the static liquid holdup by about 80% at rotational speed from 0 to 2,400 r/min. The average wetting efficiency can reach 100% at rotational speed of 1,600 r/min and liquid superficial mass velocity of 3 kg/(m²·s). Correlations to predict the liquid holdup and wetting efficiency in the RTBR were developed, and deviations between experimental and calculated values were within ±15 and ±10%, respectively. The findings of the current work provided basic data for the potential catalytic reactions limited by mass transfer in the RTBR.