Pulsed Perforated-plate Column Research Articles

Cooperative influence of D2EHPA and TBP on the reactive extraction of cobalt from sulfuric acid leach solution in a horizontal semi-industrial column

This article concerns the recovery of cobalt from a sulfuric acid leach solution in a horizontal pulsed perforated-plate column. Firstly, the influence of initial aqueous pH and the concentration of di(2-ethylhexly) phosphoric acid+tri-butyl phosphate has been investigated. It is observed that the mixture of these extractants is able to satisfactorily extract Co(II) from sulfate solution. Moreover, the influences of operational parameters including the phase flow rates along with pulsation intensity on the holdup, drop sizes and their distribution as well as extraction and stripping efficiencies and dispersion coefficients have been evaluated. Results show the highest efficiency of 95.3% and 93.2% for extraction and stripping of Co(II) at pulsation intensity of 1.30cm/s. Finally, new correlations for predicting mean drop size and holdup in the column are presented, which provide the average absolute relative error of 8.27% and 5.46% respectively.

Backmixing in Karr Reciprocating-Plate Extraction Columns

A study of backmixing in the continuous phase has been presented for a 50 mm diameter Karr reciprocating-plate extraction column using the two-phase system kerosene/tributyl phosphate (continuous)−phenol−water (dispersed). The column was operated in the emulsion region with nylon plates of 45% open area. Backmixing was determined using the unsteady-state tracer injection technique in which tracer concentrations at two distinct locations in the column were measured. Operating parameters, including frequency and amplitude of agitation and solvent and aqueous-phase flow rates, have been studied over a range of values to investigate their influence on the extent of backmixing in the continuous phase. A model based on the “two-zone approach” model used for predicting backmixing performance in a pulsed perforated-plate column (Prvcic, L. M.; Pratt, H. R. C.; Stevens, G. W. AIChE J. 1989, 35, 1845−1855) has been refitted for the current data to predict the effects of continuous-phase backmixing in a Karr reciprocating-plate column. Results indicate that the backmixing coefficient can be predicted within 13% using this model.

The use of pulsed perforated plate extraction column for recovery of sulphuric acid from copper tank house electrolyte bleeds

In this investigation the use of a pulsed perforated plate extraction column is considered for the recovery of sulphuric acid from copper tank house electrolyte bleed using a solvent extraction process based on tris(2-ethylhexyl)amine, TEHA. The hydrodynamic and mass transfer performance of the extraction column is presented and forms the basis for scale up. The results of the pilot plant experiments have demonstrated the viability of operating the acid recovery process using a pulsed perforated plate column.

COMPARISON OF HYDRODYNAMIC AND MASS TRANSFER PERFORMANCE OF SMR, RASCHIG RING AND PULSED PERFORATED PLATE COLUMN

ABSTRACT Cyanex 923 has been proposed as an extractant for the removal of sulphuric acid from copper tank house bleed streams. This process requires many stages and so is ideal for column operation. This paper presents a comparison between three types of column for this service. The new SMR packing marketed by Glitsch is the first packing developed specifically for liquid-liquid extraction service and is compared with a column packed with Raschig rings and a pulsed perforated plate column.

Transverse Dispersion and Maldistribution in a Pulsed Perforated-Plate Extraction Column

Transverse eddy diffusivities of dispersed phase drops in a 0.30-m diameter pulsed perforated plate column were determined by two methods involving measurement of changes in local holdup over the column half cross sections, one of which was initially drop free and the transfer of color tracer over the cross sections, in only one of which tracer was present initially. Both methods indicated a relatively low diffusivity of ∼10 -4 m 2 /s for both emulsion and intermediate regions of operation. However, similar tracer measurements of the radial diffusivity for the continuous phase indicated virtually complete mixing at the inlet stage. It is concluded that the reduced performance of these columns with increase in diameter in previous reports must have been due to initial maldistribution at the dispersed phase distributor at low throughputs, and a proposal is made for a more suitable form of distributor.

DISPERSED PHASE HOLDUP IN PULSED PERFORATED PLATE COLUMNS

ABSTRACT Data on dispersed phase holdup are presented for a range of aqueous-organic systems, and are used to assess the accurancy of existing methods for its prediction. The Griffith model (2) for the mixer-settler region and the Thornton correlation (3) for the dispersion region were found to be the most accurate for high interfaclal tension systems; however their application requires a knowledge of the transition pulse velocity. No technique was found to predict satisfactorily the measured holdup for the low interfaclal tension systems investigated. The refitted Bell and Babb correlation (14)was found to provide an accurate method of interpolating data for a particular system, and can also be used to predict the transition from mixer-settler to emulsion operation.

パルサーフィーダー型パルスカラムにおける液滴径

A pulsed perforated-plate column (pulsed column) is controlled by varying the operating conditions as the pulsing conditions and the flow rates of inlet and outlet streams. Changing these variables causes the fluid behavior to vary with position in the column. In a previous paper, the axial holdup in a pulsed column of pulser feeder type are obtained by using the TBP in kerosene-water system with nozzle plates or sieve plates.In the present paper, the droplet diameter of mixer-settler region in the pulsed column is studied. First, the mean droplet diameters are obtained in the dispersed aqueous (water-soluble dyestuff) and the dispersed organic (oil-soluble dyestuff) modes. Experimental results showed that both of the plate types and the operating conditions affected the mean droplet diameters. The droplet diameters become smaller with the nozzle plate than with the sieve plate. Then, both of the correlations as a function of the pulse amplitude-frequency products and the calculation models, by using the Group Method of Data Handling (GMDH) shown at a previous study of the authors, are obtained, The prediction error of calculation medels become smaller compared to the correlations. From the results of GMDH method, it was also found that the mean droplet diameter was assumed to be a function of the pulse amplitude-frequency products, the linear velocity of both phases and the plate spacing: dp∝ (af, ud, uc, Lo).

パルサーフィーダー型パルスカラムにおける軸方向ホールドアップ Ｉ ノズルプレートとシーブプレート

A pulsed perforated-plate column is controlled by varying the operating conditions as the pulsing conditions, the initial loading conditions, the A/O ratios and the flow rates of inlet and outlet streams. Changing these variables causes the holdup to vary with position in the column. As a result, it is necessary to know the axial holdup in order to obtain complete dynamic mass transfer equation.In the present paper, the axial holdup of dispersed phase in a pulsed perforated-plate cdumn, pulser feeder type, is studied. The column is made of Pyrex glass, 5cm I.D. and 100cm in actual length. Both nozzle plates and sieve plates with same cartridge geometries are used in the column. The liquid system is TBP in kerosene-water. The axial holdup data are obtained in the dispersed aqueous and the dispersed organic modes. Experimental results show that the plate-type affect the axial holdup distribution. The tendency of the axial holdup to the nonuniformity is counteracted by the nozzle plate.

訂正

訂正

パルサーフィーダー型パルスカラムにおける軸方向ホールドアップ ＩＩ ＧＭＤＨによるモデル化と分析

In mathematical models for a pulsed perforated-plate column, the dispersed phase holdup has been considered to be uniform throughout the length of the column, but fairly recently it is treated as being nonuniform.In the previous paper, the axial holdup data were obtained in the dispersed aqueous and the dispersed organic modes. Experimental results showed that the axial holdup data become nonuniform throughout the column. It was also found that both of the plate type and the operation mode affected the axial holdup distribution.The present work is an attempt to formulate the axial holdup by means of a heuristic selforganization method that provides a nonlinear prediction model of complex system, since the holdup data did not directly show so significant trend as to formulate the axial holdup. The Group Method of Data Handling (GMDH) is used for this purpose. The GMDH can be used fbr selection and synthesis of input variables concerned with the axial holdup for the pulsed perforated-plate column. The axial holdup data have been successfully correlated and the identification models could be useful in discussing mathematical models.

Backmixing in pulsed perforated plate columns

Backmixing in pulsed perforated plate columns

Influence of mass transfer direction on efficiency of a pulsed perforated plate column

The purpose of this paper is to give a complete analysis of the influence of mass transfer direction on the performance of a pulsed perforated plate-column. The ternary system studied was water—iodine—carbon tetrachloride. Both mass transfer directions were considered, i.e. iodine transfering from continuous aqueous phase to dispersed organic phase and vice versa. Parameters considered are overall efficiency, hold up, true number of transfer units, Peclet number for both phases, drop size, interfacial area and overall mass transfer coefficient.

Longitudinal mixing in the dispersed phase in pulsed perforated-plate columns

A method is presented to identify flow model parameters from radioactive signals with a high noise content. The method is based on the two detection points method with a highly accurate identification of the parameters by optimization in the frequency domain. The study of dispersed phase of a pulsed column with perforated plate using this method has shown evidence that there are operating conditions for which the piston-diffusion flow does not describe well the behavior of the dispersed phase.

The Performance Characteristics of Pulsed Perforated Plate Columns

Liquid-liquid extractions of acetic acid from acetic acid-methyl isobutyl ketone solution by means of water were studied in a pulsed perforated-plate column. Holdup of dispersed ketone phase and transfer rate of acetic acid, from which (HTU) oe was calculated, were measured, and the performance characteristics of pulsed perforated-plate column based on the variation of holdup with the pulsed velocity was studied.Three operation regions are defined from plots of holdup versus pulsed velocity of various conditions. Holdupcurves are divided into three parts; the mixer-settler region where holdup decreases with increasing pulsed velocity; transition region where holdup increases slowly; emulsion region where holdup increases abrubtly.(HTU) oe decreases with increasing pulsed velocity in the mixer-settler and transition regions, and increases in the emulsion region. Therefore, the minimum value of (HTU) oe is obtained at the boundary point between the transition and emulsion regions.The amf value at the two boundary points, holdup in the three operation regions and (HTU) oe in the two operation regions were correlated as experimental equations.