Mass Transfer Apparatus Research Articles

Experimental study of mass transfer in a convective mass-transfer apparatus for membrane plasma exchange

The possibility to achieve a high degree (up to 90%) of blood plasma exchange in a single-stage, three-channel, countercurrent convective mass exchange apparatus (CMEA) has been confirmed with the use of a model suspension as an example. It has been shown that CMEA is more efficient than a plasma filter at high (over 50%) degrees of plasma exchange.

Calculation of the Average Velocity of the Liquid in the Stream-Film Contact Devices

One of the most effective ways of energy saving is to upgrade the existing heat-mass transfer devices. To increase the efficiency of mass-transfer apparatus, a stream-film (bubble) contact device is suggested. The paper considers the prospects of using stream-film contact devices for heat-mass transfer apparatus. The distinctive feature of the developed device is an intensive countercurrent contact between the gas and liquid in each element. Dependences of the volume flow rate of gas involving turbulence in the flow volume at different design parameters are set.

DYNAMIC RETAINING CAPACITY OF THE REGULAR PACKING

This article describes researching the dynamic retaining capacity of existing regular packings for mass-transfer apparatuses. As a result of this research an improved design of the packing with a lower dynamic retaining power was developed.

Assessment of Change in Torque of Stream-Bubble Contact Mass Transfer Devices

A stream-bubble contact device for mass transfer apparatuses that enhances the efficiency of mass transfer processes is proposed. This device uses the energy of liquid streaming from the top downward, which reduces vapor (gas) phase hydraulic resistance. Also, because of reduced separation space, the overall dimensions of mass transfer apparatuses with the installed stream-bubble contact devise decrease. The results of change in torque, with due account of change in characteristic parameters of the contact device, are reported.

Membrane plasma exchange in a countercurrent convective mass-transfer apparatus

The feasibility of exchange of blood plasma in a three-channel, countercurrent convective-mass exchange apparatus (CCMEA) has been theoretically considered. Fundamental advantages of CCMEA over a blood plasma filter have been noted. Calculations based on a mathematical model show a possibility of attaining a 90% or higher degree of CCMEA plasma exchange in the absence of blood thickening and almost at any flow rate of the blood drawn from and returned to the patient, including a low flow rate, which is very important in procedures of this kind.

Sanitary treatment of gas emissions from ammonia in the production of soda ash

The research results of the effectiveness of the spray vortex countercurrent mass transfer apparatus in the absorption of ammonia are given. The main sources of ammonia emissions in the production of soda ash and disadvantages of existing industrial units are determined. The analysis of structural mass transfer equipment, which appears in recent years, allows to identify one of the areas of mass transfer technology - the spray apparatus with high degree of turbulence. High velocity of gas (steam) also allows to atomize of liquid droplets of small size and to accelerate the process by increasing the interfacial mass transfer surface. It is developed and proposed the modernized sanitary washing apparatus for process gases. It is shown that the minimum entrainment in fluid vortex devices have a spray liquid specific design. The value of entrainment after vortex devices is much smaller than the entrainment after bubbling plates. The entrainment reducing will increase the driving force for mass transfer process, and increase the absorption of the gaseous ammonia. The operation of the upgraded unit for sanitary flushing process gases is researched and graph of the characteristics of the device is shown.The research results of the absorber of sanitary cleaning of gaseous ammonia have shown that it operates stably in a wide range of loads on the machine phases. The effectiveness of the new device is significantly higher than the efficiency of the existing enterprise sanitary washer. The efficiency is rather high vortex apparatus and reaches more than 99 % in the entire range of each of the factors.

Mass transfer in the apparatuses with preformed packing bodies

The article describes the various types of preformed and random packing for heat and mass transfer apparatuses, and determines their advantages and disadvantages. It is shown that preformed moving packing is of considerable interest to the intensification of heat and mass transfer processes due to the possibility of establishing regular vortex structure in the contact zone. There are represented the results of experimental studies of hydraulic resistance, coefficient of longitudinal mixing liquid, mass transfer coefficient in the gas and liquid phases in the apparatuses both with a preformed moving sheet and ball tips. Empirical equations for calculating main hydrodynamic and mass transfer intensity characteristics have been obtained.

Heat and mass transfer tests of minicircular nozzles of polymeric material

The experimental research minicircular nozzle type MCS. It has been shown that it may be useful in a number of column heat and mass transfer apparatus.

Mathematical modelling, dynamic and mass-transfer calculation of gas-drop mixture in the mass-transfer apparatus multistage channels

The research paper is focused on the development of the drops movement mathematical model in the gas flow in the mass transfer apparatus multi-stage channel. Gas dynamic characteristics for the laminar and turbulent conditions have been stated accordingly to the numerical solutions of the Navier-Stocks and Reynolds equations systems. Method of the drops curve calculation in the masstransfer apparatus contact area has been developed. Solvability of the mathematical models equations and the used numerical systems convergence has been illustrated. The obtained gas and drops dynamics data form the basis of the

Introduction of Crossflow Drop Traps for Intensifying Mass Transfer Apparatus Operation

This paper presents an analysis of the counterflow and crossflow drop traps (demisters) installed in the feedstock injection area of pyrogas sodafining column. It is shown that the “square” and “two-lane” type of two-tier irrigated crossflow drop traps that are installed in the feed areas of vacuum columns and have separating-rectifying properties are operationally efficient. Crossflow drop traps significantly intensify mass transfer separation process owing to improved hydrodynamic conditions of primary separation of two-phase flows in the feedstock injection area.

Process Engineering Evaluation of Modern High Performance Packings for Mass Transfer Apparatus

Modern packing technology is presented in terms of correlations and criteria for an extensive evaluation of up-to-date packing design used in current mass transfer operations. The corresponding basic information covers the process engineering aspects, e.g. volumetric effectiveness and optimum geometry of the packing, and the techno-economic aspects, e.g. when selecting a packing adopted in practice for a certain application task. The correlations required for this investigation are derived and evaluated on the basis of a comprehensive experimental research by testing and comparison of modern packings, such as Raschig Super-Rings and reference packings. The results thus obtained are correlated and presented in graphic presentation of diagrams, figures and tables.

Calculating the efficiency of mass transfer columns based on analogy of momentum and mass transport in bubbling layer on trays

A method is considered for calculating the efficiency of trays and columns based on the hydrodynamic analogy of momentum and mass transport in a bubbling layer on the contact devices of mass transfer apparatuses.

Classification of nozzles of mass transfer apparatuses

The detailed classification of nozzles of heat and mass transfer apparatuses is proposed. Examples of the constructive design of new types of domestic and foreign disordered and ordered nozzles are given.

Some problems of separation of mixtures

The paths of the development of research and the change of priorities in the area of separation of mixtures are tracked by the example of analysis of the works of the laboratory founded by N.M. Zhavoronkov in 1945. The studies performed encompass a wide range of basic problems of heat and mass transfer in gas absorption, distillation (including vacuum, molecular, etc.), fractional crystallization, and melting. The subjects of the works under consideration include separation of isotopes of light elements, design of mass-transfer apparatuses with high unit power, investigation of the mechanism and kinetics of separation processes, studies of separation enhancement methods, and development of hybrid energy-and resource-saving processes and equipment.

Film thickness in unstable modes of upward cocurrent flow

The film thickness is one of the most important parameters characterizing the operation of film-type gas-liquid heat-and mass-transfer apparatuses.

Mass transfer in a medium with a rapidly renewed interface

Specific features of the mass transfer in a medium with a rapidly renewed interface are theoretically analyzed. It is shown that, in the case of intense renewal of the interface, if the adsorption of gas molecules on the liquid surface is taken into account, an additional number of molecules of the substance being dissolved are transferred to the bulk of the liquid by convective transfer of surface adsorption layers. If this process is taken into account, there is an additional mass flux into the liquid and, consequently, the mass-transfer rate is higher. In particular, this allows one to increase the concentration of the substance being dissolved above the thermodynamically equilibrium value in the absence of chemical reaction. Types of mass-transfer apparatuses in which the considered mode can be realized are discussed.

Mass Transfer between Fine-Dispersion Flows in Channels Separated with a Permeable Membrane under the Action of an Alternating Pressure Drop

A mathematical model is constructed for convective mass transfer between fine-dispersion flows separated with a permeable membrane in a valve-pulsed mass-transfer apparatus. The mass transfer is intensified owing to the repeated transverse exchange of portions of the continuous phase between the flows under the action of an alternating pressure drop. Interfacial mass transfer in the flows is taken into account under the assumption that the overall mass-transfer process in fine dispersions is controlled by transfer in the continuous phase.

Membrane crystallization of lysozyme: kinetic aspects

The relevant kinetic aspects related to an innovative method of biological macromolecules crystallization based on microporous hydrophobic membranes, used both as active surfaces to promote heterogeneous nucleation and as a mass-transfer apparatus to concentrate macromolecular solutions by solvent removal in vapour phase, have been evaluated. Polypropylene membranes, supplied in the form of hollow fibres, have been aligned in a versatile system, designed for an on-line spectrophotometric monitoring of hen egg white lysozyme crystallizing solutions (experimental conditions: 0.1 M NaAc/HAc Buffer pH 4.6, 0.5–5.8% wt/vol NaCl, 20°C). The turbidity measurements have been exploited in order to follow: (i) the induction time of crystallization, (ii) the early stage nucleation kinetics based on the Rayleigh scattering theory, and (iii) the crystal growth rate (coupled with data evaluated from image-analysis carried out by optical microscopy) under a model hypothesis of exponential growth of clusters. The crystals have been qualitatively assessed by an X-ray crystallographic analysis carried out at the synchrotron light laboratory ELETTRA.

Mathematical Model of a Mass-Transfer Apparatus for Producing a Foamed Liquid with a Desired Microstructure

A mathematical model is developed to describe the bubble formation from a gas outflowing through microholes into a liquid. The model is valid over wide ranges of gas-flow rates, gas/liquid pressure drops, and the thermophysical properties of the liquid. The calculated results agree well with the observed data. A model is proposed to characterize the hydrodynamics of and mass transfer in laminar liquid flow in a coaxial mass-transfer apparatus with a gas-permeable inner tube. Numerical data are reported for the effect of the operating parameters of the mass-transfer apparatus with a specified matrix (inner tube) microstructure on the bubble- size distribution and the volume concentration of bubbles in the liquid.

Scaling-up Effect in Chemical Engineering

Basic principles of scaling-up theory and a method of hydrodynamic modeling of mass-transfer apparatuses are considered. The hydrodynamic nature of the scaling-up effect is demonstrated by a number of examples, including industrial-scale apparatuses up to 12 m in diameter, and ways of eliminating this effect are discussed.