ANALYSIS OF THE COIL CENTRIFUGAL FORCE FIELD IN COUNTERCURRENT CHROMATOGRAPHY

1 INTRODUCTIONCountercurrent chromatography(CCC)is a true liquid-liquid partition chromatographywhich totally eliminates the use of a solid support.Being a support-free system,themethod offers a number of advantages over other chromatographic methods byminimizing problems arising from the use of solid supports such as adsorptive loss andinactivation of samples,tailing of solute peaks,contamination,etc.In practice,CCCprovides its greatest advantage in preparative-scale separations where high-performanceliquid chromatography(HPLC)suffers loss of partition efficiency and high

Branch Quality Control of Gas-Liquid Two-Phase Flow Using a Novel T-Junction Type Distributor

In order to eliminate mal-distribution and ensure the side arm to produce desirable gas quality a special distributor is proposed. The experimental distributor mainly consists of a straight through section,a gas extraction line,a liquid extraction line and a side arm branch. A gas orifice and a liquid orifice are mounted at the gas and liquid extraction line respectively to control the outlet gas quality. The diameter of the liquid orifice was set to 2. 50 mm and three gas orifices with different size( dG= 2. 65,5. 00,10. 00 mm) were tested. The experiments were carried out at an air-water two-phase flow loop. The gas superficial velocity ranged from 6. 0 to 20. 0 m /s and the liquid superficial velocity was in the range of 0. 02- 0. 18 m /s. Flow patterns such as wave flow,slug flow and annular flow were observed. The gas quality of the side arm branch was found mainly determined by the flow area ratio of the gas orifice to the liquid orifice and independent of gas and liquid superficial velocity,flow patterns and extraction flux.

PERFLUOROOCTANESULFONIC ACID CATALYZED FRIEDEL-CRAFTS ALKYLATION WITH OLEFINS IN GAS-LIQUID PHASE

Solid superacid perfluorooctanesulfonic acid(POSA)catalyzed Friedel-Crafts alkylation of aromatic hydrocarbons with olefins in gas-liquid phase.The alkylations gave good yields with simple operation and easy work up.The amount of the catalyst used in the reactions was small and could be reused.The optimum temperature of the reactions and the effect of the amount of the catalyst used in the reactions are also discussed.

Deviation of Carbon Dioxide-Water Gas-Liquid Balance from Thermodynamic Equilibrium in Turbulence h Experiment and Correlation

The carbon dioxide-water system was used to investigate the flowing gas-liquid metastable state. The experiment was carded out in a constant volume vessel with a horizontal circulation pipe and a peristaltic pump forced CO2 saturated water to flow. The temperature and pressure were recorded. The results showed that some CO2 escaped from the water in the flow process and the pressure increased, indicating that the gas-liquid equilibrium was broken. The amount of escaped CO2 varied with flow speed and reached a limit in a few minutes, entitled dy- namic equilibrium. Temperature and liquid movement played the same important role in breaking the phase equilib- rium. Under the experimental conditions, the ratio of the excessive carbon dioxide in the gas phase to its thermody- namic equilibrium amount in the liquid could achieve 15%.

Performance Prediction of the Helico-axial Multiphase Pump

A modified one-dimensional model is developed for prediction of multiphase pump performance. Taken into account in the model are the gas compressibility, the slip speed gap between two phases and the flow cross-sectional depth gradient in the flow line. By using this model, we can select appropriate geometrical parameters of the impellers and guide vanes, and thus higher-pressure boost is obtained but phase separation does not occur. Accordingly, the design method can be optimized. The drag coefficients are analyzed for different flows. Results predicted by the modified model are compared with a series of experimental data and found in good agreement. This model provides a convenient and economical tool for engineering design over a traditional one.

Comparison of One-Dimensional Analysis with Experiment for CO₂Two-Phase Nozzle Flow

The aim of this study is to investigate CO2 two-phase nozzle flow in terms of both experimental and analytical aspects for the optimum design of two-phase flow nozzle of CO2 two-phase flow ejector. In the experiment, it is measured that the temperature profile in the stream-wise direction of a divergent-convergent nozzle through which CO2 in the supercritical pressure condition is blown down into the atmosphere. In the analysis, a one-dimensional model which assumes steady, adiabatic, frictionless, and equilibrium is proposed. In the convergent part of the nozzle the flow is treated as single-phase flow of liquid, whereas in the divergent part the flow is treated as separated two-phase flow with saturated condition. The analytical results indicate that the temperature and the pressure decrease rapidly in the divergent part, and the void fraction increases immediately near the throat. Although this analysis is quite simple, the analytical results can follow the experimental results well within this study.

气泡运移特征可视化观测装置研制及应用

气液两相流动过程中,气泡的形态变化时刻影响着流动的发展。为分析气泡在运移过程中的形态变化,该文研制了一套气泡运移特征可视化观测装置,包括管道模块、动力模块及数据采集模块。为了验证装置的可靠性,开展了不同液相黏度、不同液速及不同管道倾角下的气泡运移实验。实验结果表明,该装置操作简单、功能多样,可清晰地展示并记录气泡在不同液相环境下的运移轨迹及状态,并得到气泡的速度变化数据,实验结果直观可靠。结果证明该装置可解决因气泡运移特征复杂、影响因素多而难以获取直观数据的问题,对研究气液两相流动及气泡动力学领域的相关问题具有一定意义,可推广应用。

逆流相分离结构微细通道流动沸腾传热与均温性

为探究不同相分离结构参数对强化微细通道流动沸腾传热性能和均温性的影响,加工制作了带有不同相分离结构的平行逆流微细通道试验段,分别为相分离结构(PSS)位置不同的PSS-1(上下游均匀分布)、PSS-2(上下游靠近中部)和PSS-3(上下游靠近两端),其中PSS-1分为A、B、C三种,分别对应4孔、6孔、10孔。以乙醇为试验工质,在有效热通量为17.12~87.25 kW/m^(2)、入口温度为70℃、质量流速为86.11 kg(/m^(2)·s)的工况下,对截面为2 mm×2 mm的矩形微细通道开展流动沸腾试验,并利用高速摄影仪对通道进行可视化研究,通过引入传热强化因子和壁面温度标准差研究了不同相分离结构对强化微细通道传热性能和均温性的影响以及相分离结构在高压通道和低压通道内的强化机制。研究表明,传热强化效果随相分离排气孔数增加而提升,相分离结构位置对传热特性的影响在高压通道和低压通道内有所不同。PSS-1-C微细通道的温度均匀性最好,在热通量为83.11 kW/m^(2)时微细通道平均壁面温度较无相分离相同通道降低了1.9℃,温度标准差降低了14.2%。可视化图像表明,相分离结构在压差作用下能实现气相转移,进而强化传热。

高速逆流色谱分离纯化枸杞多糖在神经炎症中的作用

目的:构建高速逆流色谱技术分离纯化枸杞多糖的新方法,并对分离得到的枸杞多糖进行结构表征,探究其对神经炎症的影响。方法:通过分配系数K值和固定相保留率Sf,筛选并优化双水相体系偶联高速逆流色谱分离纯化枸杞多糖的条件,利用高效分子排阻色谱联用激光光散射仪和示差检测器串联检测法、1-苯基-3-甲基-5-吡唑啉酮柱前衍生结合高效液相色谱法、傅立叶变换红外光谱仪、热重分析仪、扫描电子显微镜对枸杞多糖进行初步结构表征,利用脂多糖诱导的小胶质细胞炎症模型研究枸杞多糖对神经炎症的作用。结果:确定最佳双水相体系为乙醇、饱和硫酸铵、水、异丙醇的质量比为1.4:1.0:2.58:0.3,高速逆流色谱最佳分离纯化条件为转速900 r/min,流动相流速0.8 mL/min。在上述条件下,分离得到3个枸杞多糖组分LBPs-1、LBPs-2和LBPs-3,多糖含量分别为78.35%±1.52%,69.03%±1.71%和62.11%±2.31%,分子量分别为7.40×10^(4) Da,2.73×10^(4) Da和1.47×10^(4) Da,单糖组成分别为甘露糖:鼠李糖:半乳糖醛酸:葡萄糖醛酸:葡萄糖:半乳糖:阿拉伯糖,其中摩尔比分别为1.9:4.9:1.3:8.1:7.6:32.6:41.8、2.1:4.3:1.5:8.3:5.1:28.6:37.9和5.9:4.6:1.1:0.7:13.8:66.8:5.3,同时热稳定性和微观形貌也有明显差异。生物活性研究结果表明,不同分子量的枸杞多糖可通过抑制炎症因子分泌,缓解脂多糖诱导的小胶质细胞炎症。结论:本研究构建了双水相体系偶联高速逆流色谱分离纯化枸杞多糖的新方法,为植物多糖高效分离纯化提供了技术支撑,为枸杞多糖在抑制神经炎症相关疾病中的应用提供了科学依据。

多级双水相萃取木瓜蛋白酶的研究

使用双水相萃取大规模生产木瓜蛋白酶时,为获得较高的回收率,通常需要较高的萃取剂浓度和体积比,但这会导致目标物的纯度和浓度降低。该研究采用聚乙二醇和柠檬酸钠组成的双水相体系在多个离心管之间的转移来模拟工业上常用的多级错流萃取和多级逆流萃取过程,以分配系数、酶活性回收率为指标,采用McCabe Thiele图解法得到多级逆流双水相萃取的理论级数,结果表明,当相比为0.5,原料液下相的木瓜蛋白酶的初始质量浓度为0.20 mg/mL时,使用3级逆流双水相萃取木瓜蛋白酶的酶活性回收率达到了96.75%,同时设计出多级逆流双水相萃取木瓜蛋白酶的优化方案。

Study on two-phase countercurrent flow and transport phenomenon in PEM of a direct methanol fuel cell

Based on the requirement of water management for a direct methanol fuel cell, this paper analyzes qualitatively the mechanism of occurrence and development of a two-phase countercurrent flow with corresponding transport phenomenon in the PEM. A one-dimensional, steady state quantitative model of heat and mass transfer in internal volumetric ohmic heating porous media saturated by liquid and vapor phases is developed. The effects of capillarity, electro-osmotic drag and phase change are included. Two im-portant formulas to calculate the theoretical length of two-phase zone δ t and determine the critical criterion |?ω /γ |cr for dryout in PEM are deduced. By use of these two dimen-sionless parameters, dryout of PEM can be easily predicted. Theoretical temperature, pressure and saturation profiles within the two-phase region are obtained numerically, which can help to explore the performance of a DMFC operating in its ohmic polarization region. The simulation results can be used to determine the catalyst content of cathode catalyst layer and the corresponding optimal thickness of PEM.

致密砂岩气藏负压差水相圈闭损害过程模拟

致密砂岩气藏具有低孔低渗透、高毛管压力、天然裂缝发育和超低含水饱和度等工程地质特征,存在明显的毛管自吸现象,即使在负压差条件下,毛管压力也会使水相逆流自吸进入储层,引起水相圈闭损害。选用鄂尔多斯盆地典型致密砂岩气藏相对低渗透(渗透率小于0.2×10^(-3)μm^2)、相对中渗透(渗透率为0.2×10^(-3)~0.5×10^(-3)μm^2)和相对高渗透(大于0.5×10^(-3)μm^2)的3类致密砂岩岩样,开展水相毛管逆流自吸实验和气驱水返排实验,模拟负压差条件下水相圈闭损害发生过程,探讨水相逆流自吸对气相渗透率的影响,评价负压差条件下水相圈闭损害程度。实验结果表明:负压差下水相逆流自吸对气相渗透率的损害呈现由岩样物性控制的阶跃式变化特征。同一负压差下,3类岩样气相渗透率损害率为26.5%~34.9%,平均损害率为29.8%;负压差越小,对毛管压力的克服作用越弱,毛管自吸越明显,水相进入岩心位置越深,引起的水相圈闭损害越严重。因此,在欠平衡钻井、完井和开发过程中,确定生产压差时应综合考虑安全作业、储层水相返排等因素。

利用高速逆流色谱分离邻苯二酚和对苯二酚

利用高速逆流色谱(HSCCC)成功分离了邻苯二酚和对苯二酚这一对同分异构体,以正己烷 乙酸乙酯 甲醇 水为溶剂系统,分离效果最好时的溶剂体积比为7∶3∶6∶4,以上相为固定相,下相为流动相,流动相流速为0 5mL min。

高速逆流色谱技术在生物大分子分离纯化中的应用

高速逆流色谱是一种连续液-液色谱技术,具有无固相载体、样品无需严格预处理等优点。近10年来,在设备结构和溶剂体系等方面进行了大量的研究开发,已推广应用于生物技术、医药、天然产物、环境监测、食品等领域。为适应生物大分子和活性细胞的分离,采用条件温和的双水相体系,研究开发相应的高速逆流色谱设备已成为热点。针对双水相体系的特点,已经开发出了多种具有较高固定相保留率的新型高速逆流色谱设备,通过优化实验条件,成功地进行了多种蛋白质的分离纯化。本文对该领域的最新进展进行了综述与评价。

含锰磁铁相还原氧化锰矿的浸出工艺

针对含锰磁铁相的还原氧化锰矿浸出效果差的问题,以云南文山示范线还原氧化锰矿、浸出尾渣为主要研究对象,考察起始酸度、浸出时间和浸出温度对锰磁铁相浸出反应的影响;在明确锰磁铁相浸出规律基础上,优化浸出工艺。结果表明,锰磁铁相在较高酸浓度梯度下,能保持较快的浸出速率;先后采用质量浓度为48.02 g/L的起始酸浸出一氧化锰相,76.44 g/L的浸出锰磁铁相的两段逆流浸出工艺,比单段浸出工艺,锰浸出率从82.31%增加到92.17%,酸耗(酸矿质量比)从0.55减少到0.50。

倾斜油水两相流水为连续相的逆塞流及过渡流型非线性特性

在倾斜油水两相流模拟井装置上,利用自制的纵向多极阵列电导传感器,测量得到了66组不同倾斜角度的油水两相流电导波动信号。采用Hurst指数和吸引子形态描述方法提取了波动信号的非线性特征,通过研究Hurst指数、吸引子形态特征量与流型之间关系,发现倾斜油水两相流电导波动信号的Hurst指数介于0.6～0.9之间,4阶吸引子形态特征量对流型转化敏感。结果表明,4阶吸引子形态特征量的组合能够有效识别水为连续相的逆塞流型和过渡流型。

规整填料内气相载荷对液膜流动特性的影响

为研究逆向气相载荷对规整填料表面液膜流动特性的影响,采用流体力学计算软件FLUENT建立基于Navier-Stokes方程和VOF方法相结合的CFD分析模型,湍流结构模拟采用RNG k-ε模型。针对Mellapak 250Y型金属板波纹填料表面不同气相载荷(F因子)对液膜流体动力学特性的影响进行模拟分析。研究各工况下液膜动态运动分布、气液两相流场结构、界面速度场分布特征,及相应持液量、有效界面传质面积变化分布规律。研究结果表明:气相速度对上述参数均有不同程度影响。

逆流浮选的相际平衡与充气量

用相际平衡原理研究了逆流浮选过程 ,提出了最小气液比和最小充气量的概念 ,得出浮选充气量与入浮矿浆中目的矿物量及工艺要求的精煤回收率之积成正比 ,与矿化气泡中目的矿物浓度成反比等结论 ,为逆流浮选柱的充气量设计提供了理论依据 .

降低活性炭脱硫塔阻力的实验研究

针对实际运行中的活性炭脱硫塔阻力大、能耗高、效率低的问题,采用不同结构的支承装置,模拟实际运行工况,对其阻力特性进行了实验研究。结果表明,在平板支承装置上加装“T”型和倒“L”型导气管,使液相速度场与气相速度场达到了一定的协同效应,有效降低了床层阻力,提高了脱硫塔脱硫效率。

全逆流混合澄清槽中萃取体系料液流场CFD模拟研究

为了研究全逆流混合澄清槽内气-液(水相)-液(有机相)三相流体在微观层面的行为,本文采用CFD方法,以全逆流混合澄清槽为对象进行了研究。结果表明,搅拌会在混合室内产生一个V型液位分布,桨叶后方出现负压区域,且上部会出现空化现象;正方形混合室的四角方向会出现压力滞止死区;混合室内有机相会出现围绕搅拌轴的包覆层,水相主要从桨叶正下方吸入后与有机相在桨叶区域进行混合;混合室内存在多个局部速度旋涡场,桨叶下部是四周液体向桨叶正下方汇集,桨叶上部则是先向上后向旋转轴汇集;两相的混合与液滴的破碎与并聚主要发生在桨叶处及混合室附近壁面上。