环隙式离心萃取器流场研究进展

围绕工业应用,人们在环隙流场稳定性、水力学特性等方面做了大量研究,而对环隙的流场流动机理、泰勒涡流场结构等方面的研究较少,随着线性和非线性理论、计算流体力学和流动可视化技术的飞速发展,对环隙流场流动机理、涡流场的结构进行详细直观描述有了可能,主要从环隙流场可视化、环隙流场数值模拟2个方面对该研究进行了系统的分析总结,并为将来的研究工作提出了几点意见。     

φ50环隙式离心萃取器的水力学性能

<正> 环隙式离心萃取器是我校核能研究所仿美国国立阿贡研究所的ANL-4型离心萃取器研制成的,它已被成功地用于多种化工产品的分离中,其结构简单,更换和组合方便,可实现国产化,是具有推广意义的机种。本文研究此种离心萃取器移植到双水相体系的水力学性能,并确定其应用的可能性。     

实验室用小流量环隙式离心萃取器的研制

CTL50-N型小流量环隙式离心萃取器作为一种快速、高效的萃取试验设备，应用广泛，效果良好。本文详细介绍了该萃取器的工作原理、技术参数、结构设计和应用方面的情况。指出通过该萃取器的试验，能直观便捷的验证许多萃取数据，为萃取工艺的确定奠定基础。     

圆筒式离心萃取器的探讨

圆简式离心萃取器具有容积效率高、处理能力大、两相停留时间短,并能分离两相密度小至0.01g/cm~2的液系,因此目前在化工、医疗、食品等行业越来越受到重视。本文介绍了该设备的基本原理、水力学特性、操作特性、结构设计等方面问题。     

φ230环隙式离心萃取器的流体力学性能研究

研制了一种φ230环隙式离心萃取器。在1500和2090rpm两种转速下,用水-煤油和食盐水-煤油两种体系做了流体力学性能实验。 实验表明设备的机械性能和水力学性能都很好。这种萃取器可以单级或多级串联用于液-液萃取的工业生产。     

圆筒式离心萃取器性能研究

以煤油—水—丁酸为体系,通过实验,研究了HL—20型离心萃取器的水力学及传质性能。一、概述圆筒式离心萃取器是60年代后期发展起来的一种离心萃取设备,与其它离心萃取器相比,圆筒式离心萃取器有其自己的特点,即结构简单,适应性强。在离心萃取器的加工中,技术要求最严格的是转鼓。不同规格的转鼓,生产能力可以从每小时几升到100m3/h,且其转鼓是上悬的,浸在液体部分的转动件没有密封的问题,消除了液体的漏液。在圆筒式离心萃取器中由于     

环隙式离心萃取分离技术研究进展

综述了国内外环隙式离心萃取分离技术的研究进展,包括环隙式离心萃取器的结构形式和参数、结构改进、流态及速度分布、水力学特性和传质特性等;介绍了环隙式离心萃取分离技术在核燃料后处理、石油化工及湿法冶金领域的应用;指出环隙式离心萃取分离技术是未来萃取技术的发展方向,环隙间传质因素及转子和堰区域的分离因素等是其今后的研究方向。     

玻璃钢离心萃取器及其应用

介绍玻璃钢离心萃取器的结构设计和性能实验，包括材料的选定，对样机进行连续运转７００ｈ的力学性能实验，以及流体力学性能和传质性能实验。结果表明玻璃钢离心萃取器具有良好的性能，可应用于工业生产有萃取、净化流程中。     

环隙式离心萃取器内部两相流动研究进展

环隙式离心萃取器是集成液-液混合与液-液分离于一体的高性能萃取设备,其广泛应用于核工业、化工环保、有色冶金、生物医药等领域。离心萃取器具有优异的水力学特性和传质特性,这主要得益于其环隙中的泰勒涡流以及转鼓内的离心分离流等特殊流动。本文主要依据离心萃取器结构和两相流动特点,综述了环隙内气-液界面变化规律、气泡流动特性、液-液两相流型、液滴流动特性,以及转鼓内的气-液界面等方面的研究进展,还总结了环隙螺旋隔板、转鼓径向叶片等结构的优化对于两相流动、混合或分离效果的影响。在后续研究中,可以从离心萃取过程中的液滴分散和聚并机理、三相流动测试及模拟、结构的模型化设计方法等方面开展更加深入的研究。     

离心萃取器在咖啡因工业生产中的应用

在咖啡因工业生产中,一般是采用静态混合器为萃取设备、氯仿为萃取剂来回收母液中的咖啡因,主要缺点是萃取率只在90％左右以及氯仿损失大。离心萃取器是一种高效的液一液萃取设备,具有许多显著优点,为此,采用了4台Ф230离心萃取器代替静态混合器组成串联逆流萃取流程,对该生产环节进行了技术改造,结果表明,萃取率提高到了99％,氯仿用量降低到了25％。     

Determination of the Liquid Hold-up Volume and the Interface Radius of an Annular Centrifugal Contactor using the Liquid-Fast-Separation Method

Annular centrifugal contactors (ACCs), which use centrifugal force to separate the dispersion of two immiscible liquids of different densities, have been utilized in many industrial fields, such as the petroleum, hydrometallurgy, wastewater treatment, pharmaceutical processing, protein extraction, enantioselective chemical separation, biodiesel synthesis, and nuclear industries. Detailed hydrodynamic information, such as the liquid hold-up volume and the interface radius, is very important for successful design and operation of ACCs. A new method, namely, the liquid-fast-separation method, was developed to (1) obtain the parameters of the liquid hold-up volume, the actual phase ratio (aqueous phase/organic phase, a/o) of two phases in the mixing zone, and the interface radius, and (2) investigate the effects of the rotor speed, the total flow rate, the flow ratio (a/o), and the diameter of the heavy phase weir on these parameters. The experimental results indicated that the parameters of the liquid hold-up volume, the actual phase ratio (a/o) of two phases in the mixing zone, and the interface radius could be obtained using the liquid-fast-separation method. Moreover, the effects of the rotor speed, the total flow rate, the flow ratio (a/o), and the diameter of the heavy phase weir on these parameters could also be obtained. These results provide a more complete understanding of the fluid flow in ACCs to enable further advancements in their design and operation.     

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.     

Evaluation of Annular Centrifugal Contactors for the Extraction of Acetic Acid from Aqueous Streams

This study investigates the use of annular centrifugal contactors for the liquid-liquid extraction of acetic acid from an acidic aqueous phase into an organic phase consisting of 1.5 M Tributyl Phosphate in n-Dodecane. Initial break time tests were performed in order to investigate the mixing/separation viability of the organic/aqueous system, and after determining that centrifugal contactors could be used to perform the liquid-liquid extraction, hydraulic tests established the combination of rotation rate and throughput which should be used to ensure proper separation of the two outlet phases. Finally, extraction efficiency data was collected to examine the system conditions that provided the most efficient removal of acetic acid.     

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%.     

Demonstration of an Improved Total Partitioning Process for High Level Liquid Waste Using Annular Centrifugal Contactors

High level liquid waste (HLLW) produced from the reprocessing of the spent nuclear fuel still contains moderate amounts of uranium, transuranium (TRU) actinides, ⁹⁰Sr, ¹³⁷Cs, etc., and thus constitutes a permanent hazard to the environment. The partitioning and transmutation (P&T) strategy has increasingly attracted interest for the safe treatment and disposal of HLLW, in which the partitioning of HLLW is one of the critical technical issues. An improved total partitioning process, including a TRPO (tri-alkylphosphine oxide) process for the removal of actinides, a CESE (crown ether strontium extraction) process for the removal of Sr, and a calixcrown ether extraction process for the removal of Cs, has been developed to treat Chinese HLLW at the Institute of Nuclear and New Energy Technology (INET), Tsinghua University, China. A demonstration test of the improved total partitioning process was carried out using 74-stage 10-mm-dia annular centrifugal contactors and simulated HLLW. The test results showed that the decontamination factors were >1.2 × 10⁶, 4600, and 7500 for Nd, Sr, and Cs, respectively. In the test, Nd was used to simulate Am. During the test, 74-stage 10-mm-dia annular centrifugal contactors worked stable continuously with no stage failing or interruption of the operation.     

Radioactive Tracer Tests of Two Improved TRPO Processes for High-Level Liquid Waste Using Annular Centrifugal Contactors

High-level liquid waste (HLLW) produced from the reprocessing of the spent nuclear fuel still contains moderate amounts of uranium, transuranium (TRU) actinides, and fission products, and thus constitutes a permanent hazard to the environment. The partitioning and transmutation (P&T) strategy has increasingly attracted interest for the safe treatment and disposal of HLLW, in which the partitioning of HLLW is one of the critical technical issues. Two improved trialkylphosphine oxide (TRPO) processes for the removal of actinides have been developed to treat Chinese HLLW, based on the original TRPO process. In one improved process N,N-diethylhydroxylamine as a reducing agent was used for reducing Np(V) and Np(VI) to Np(IV) in order to improve the extraction efficiency of Np. In the other improved process, ammonium vanadate as an oxidizing agent was used for oxidizing Np(V) and Np(IV) to Np(VI) in order to improve the extraction efficiency of Np. Radioactive tracer tests of two improved TRPO processes were carried out using 30-stage 10-mm-diam annular centrifugal contactors and simulated HLLW containing U, Np, Pu, and Am. The test results showed that the decontamination factor of total α activity was >1 × 10⁵. During the test, 30-stage 10-mm-diam annular centrifugal contactors worked in a stable manner continuously, with no stage failing or any interruption of the operation.     

Separation of Ionic Liquid Dispersions in Centrifugal Solvent Extraction Contactors

Abstract

Separations of dispersions formed by mixing immiscible organic room‐temperature ionic liquids (IL)/hydrocarbon/and aqueous systems using a centrifugal solvent‐extraction contactor have been successfully demonstrated in proof‐of‐concept testing. This accomplishment is significant in that physical property factors that are typical of ionic liquid systems (e.g., similar densities of the bulk phases, low interfacial tensions, and high viscosities) are typically unfavorable for dispersion separation, particularly in continuous processes. Efficient separation of dispersions containing ionic liquid solvents is essential for utilization of these compounds in liquid‐liquid extraction applications to maximize both solute transfer efficiency and solvent recovery. Efficient solvent recovery is of particular concern in IL applications because of the high cost of most IL solvents.

This paper presents the results of initial experiments with three hydrophobic ionic liquids to determine how their physical properties affect phase mixing and phase disengagement in contact with an aqueous solution using a centrifugal contactor. While the results of the reported work are promising, additional work is needed to optimize existing mathematical models of contactor hydraulics to address special considerations involved in IL‐based processes and to optimize the equipment itself for IL applications.     

Development of a Solvent Extraction Model for Process Tests in Short Residence Time Centrifugal Contactors

A computer program has been developed for optimization and modelling of counter–current solvent extraction processes. The distribution between the phases is calculated by either D-ratio functions or by a novel kinetic model for the transfer between the phases. The kinetic model is important to use when slow extraction kinetics yields D-ratios far from equilibrium. Transfer rate data was investigated in a single stage centrifugal contactor, modified for internal recirculation of the phases. Using this methodology a demonstration process for the recovery of minor actinides in a counter–current centrifugal contactor system using CyMe₄-BTBP was modelled with excellent agreement towards the experimental values.     

Application of Annular Centrifugal Contactor on Separating Indium from Iron

Abstract

It is hard to separate indium from iron in sulfuric acid leachate without reducing Fe³⁺ to Fe²⁺ with di(2-ethylhexyl) phosphoric acid (HDEHP) by the equilibrium extraction process. A nonequilibrium extraction process with annular centrifugal contactors is studied through the extraction kinetics difference between In and Fe. The mass transfer velocities of In and Fe were determined. Laboratory- and industry-scale extraction tests with miniature and industry scale annular centrifugal contactors, respectively, were conducted. The results indicate the mass transfer velocity of In is much faster than that of Fe, the contact time between the two phases is very short in the contactor, and the In can be well separated from Fe in the nonequilibrium extraction process with annular centrifugal contactors.     

Thirty Stage Annular Centrifugal Contactor Thermal Profile Measurements

A thirty stage 5 cm annular centrifugal contactor cascade was assembled and tested to obtain thermal profiles during both ambient and heated input conditions of operation. Thermocouples were installed on every stage as well as feed inputs, and real-time data was taken during experiments lasting from two to eight hours at total flow rates of 0.5 to 1.4 liters per minute. Ambient temperature profile results show that only a small amount of heat is generated by the mechanical energy of the contactors. Steady state temperature profiles mimic the ambient temperature of the lab but are higher toward the middle of the cascade. Heated inlet solutions gave temperature profiles with smaller temperature gradients, more driven by the temperature of the inlet solutions than ambient lab temperature. Temperature effects of solution mixing, even at rotor speeds of 4000 rpm, were not measurable.