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New Mixer for Multicomponent Media

#2619


Development of a New Conception of the Efficient Industrial Mixer for Making High-Quality Suspensions and Emulsions

Tech Area / Field

  • MAN-MCH/Machinery and Tools/Manufacturing Technology
  • PHY-NGD/Fluid Mechanics and Gas Dynamics/Physics

Status
3 Approved without Funding

Registration date
04.10.2002

Leading Institute
Central Aerodynamic Institute, Russia, Moscow reg., Zhukovsky

Collaborators

  • CNRS / Laboratoire D'Energetique et de Mecanique Theorique et Appliquee (LEMTA), France, Nancy

Project summary

Purpose.

The purpose of the Project is development of methods and facilities to considerably increase the effectiveness of mixing, suspending and emulsifying multicomponent media, to overcome harmful effects of radial separation and downward deposition of heavy mixture components in inertial and gravitational fields by organizing large periodic vortex structures with intense radial/axial circulation of the medium to be mixed.

The Project is based on a complex approach relying on a detailed investigation of hydrodynamic and physical processes governing the effectiveness of mixing of the multicomponent medium. The Project suggests developing theoretical models of multicomponent media hydrodynamics, carrying out calculations and experimental investigations, designing and manufacturing facility models and prototypes and conducting their experimental tests.

The research objects are technologies and facilities for industrial preparation of suspensions and emulsions. At the present time, the effective preparation of high-quality mixtures with uniform distributions of components to be mixed over the facility volume is very acute. Because of different density of components to be mixed, great dimensions of facilities, gravity and inertia effects, as well as some other factors, it is impossible to attain a required level of product uniformity in some technological processes or a desired uniformity is obtained at great power consumption.

The stated purpose and expected scientific/technical results will be achieved using a new method of organizing the flow of medium to be mixed. The specific features of this method realized in several variants of the mixer design [3] are as follows :

– Fluid medium is actuated at the expense of shearing stresses arising on the rotor surface, enough uniformly distributed in all volume and terminated on the body.


– Mixing is realized in a system of big cells, periodic along the axis of rotation (z), formed by shapes of the rotor R1(z) and the body R2(z) surfaces, which are periodic along z with the period.
– The surfaces of the rotor R1(z) and the body R2(z) are not cylindrical and belong to a class of continuous functions with a limited first derivative on z.
– Non zero net flux develops along the z-axis. Its mean velocity is much less than the characteristic velocity of circumferential flow.

Such a macroscopic flow organization with large periodic vortical structures, connected by common axial flow, provides a uniform distribution of immixed components in the mixer volume and effective exchange of mass and heat between different areas (including processes of dissolution of an impurity and chemical reactions).

It is suggested that the new method of mixing process organizing will be basically used for turbulent or transient laminar-turbulent flows of medium with a high deposition intensity of heavy components. In this case, the conditions of laminar flow instability and the initiation of intense small-scale turbulence are provided over the whole mixer volume with retained stable large-scale vortex structures. Mechanical energy supplied by the rotor is spent mainly for the creation of a rather intense turbulent transfer uniform over the volume.

The suggested method of mixing organization and relevant mixer designs have stemmed from the well-known method of mixing in a system of Taylor vortices formed in a gap between two coaxial cylinders with the rotating internal cylinder [1,2]. Contrary to existing designs, the new mixer is characterized by the formation of a forced vortex flow with the intensity much exceeding that of the Taylor vortices at the same power consumption as a result of a special selection of surface shapes for the rotor R1(z) and the body R2(z). In addition, the proposed shape of the internal mixer cell volume makes it possible to significantly overcome the effect of separation of mixture components having different density.

The participants of the suggested project have revealed using the constructed theoretical model and numerical simulation of working fluid flow and impurity propagation process, that the new mixer achieves a desired product homogenization 2-3 times quicker than the existing design (at less power consumption and the same initial impurity distribution) [3,4].

The most important objective of the Project is a detailed experimental validation of the effectiveness of the suggested mixing organization method using laboratory models of mixing facilities. Also, elaboration of new and modernization of existing mathematical models of multicomponent media flow, programmed realization of these models and creation of application package to calculate the operation of mixers of this type in a wide range of parameters. For developers of theoretical and numerical models the acute challenge is to make a justified and a sufficiently accurate prediction of characteristics of full-scale (industrial) mixing facilities.

Expected Results and their Application.

During the realization of the project, it is expected to obtain the following results:

a) Manufacturing of operating laboratory mixer models based on the suggested mixing organization method. These models will be used to test the effectiveness of the new mixing method and to obtain data in a scope sufficient for designing industrial mixing facilities.

b) Elaboration of new and modernization of some existing mathematical models of multicomponent media flow, programmed realization of these models and creation of application packages to calculate the operation of mixers of this type in a wide range of parameters.

Based on the investigation results, an international patent application for the invention of the mixer will be prepared which can be used in chemical, petroleum, paint and varnish, food, microbiological industries, as well as in nuclear engineering to extract residuals of uranium from the spent nuclear fuel.

The investigation results for physical and hydrodynamic processes taking place in multicomponent media flows will be published. They can be applied in wide range of industrial technologies.

Approach and Technique.

The Project will be realized simultaneously in two aspects:

1) Experimental investigations of multicomponent media flows and detailed verification of the effectiveness of the suggested mixing organization method on laboratory models of mixing facilities.


2) Improvement of existing and construction of new mathematical models of multicomponent media flow, programmed realization of these models and carrying out a series of calculation to find optimal operation regimes for mixers of this type.

The mixer concept developed by the supervisor of the Project [3,4] is taken as an initial variant. But it is not improbable that the mixer design will be significantly changed during the progress of the Project. In view of this, considerable efforts are suggested to be spent for development of laboratory models which would allow the net effect of innovations to be assessed experimentally because this information cannot be obtained, as a rule, by comparing the results published by perse authors. The investigations in both aspects are expected to be interconnected: every laboratory mixer model will be preliminarily calculated to determine optimal geometric parameters and operation regimes, while the experimental data will be used to verify and correct theoretical models.

Commercial Significance.

During the progress of the Project, several variants of the mixer design will be constructed. The mixer can be used in chemical, petroleum, paint and varnish, food, microbiological industries, as well as in nuclear engineering to extract residuals of uranium from the spent nuclear fuel.

Meeting ISTC Goals and Objectives.

The proposed Project is in full compliance with the ISTC purposes because:

– the present development is aimed at construction and industrial use of mixing facilities of exclusively peaceful application (in plants of petroleum, paint and varnish, food, microbiological industries, nuclear engineering etc.), which are characterized by much less power consumption as compared with existing counterparts;


– the present development will contribute to tackling the most important challenge facing the Russia today: re-equipment of industry with new improved technologies;
– the present Project features the commercial potential and, of course, will promote to transition to market economy;
– to realize the Project, the fundamental potential and experience of scientists and engineers of TsAGI early engaged in development of military missiles and other scientific military programs will be used, thus providing alternative employment of highly-qualified specialists and their involvement in international scientific community.

Role of Foreign Collaborators.

Our potential partners are specialists in experimental investigations of liquid medium flows (for example, Couette-Taylor flows) and application of the results obtained to develop new industrial technologies [2]. In the laboratory of Prof. Wesfreid J.-E, a cycle of investigations was carried out to use the Couette-Taylor flows for extracting residuals of uranium from spent nuclear fuel [2]. Precisely the mixer proposed by Prof. Wesfreid J.-E and his co-authors is taken as a reference in the present Project to compare quantitative and qualitative indices of mixing effectiveness.

In laboratory of the Prof. S. Skali Lami the important and interesting results of experimental and numerical researches of modified Taylor flow are obtained. In particular the fact of originating of periodic vortical structures called by a wavy rotor surface at a cylindrical surface of a body is affirmed experimentally in work [5].

The following nonfinancial participation of proposed collaborators is suggested:

– parallel experimental investigations on mixer models proposed by Russian participants of the Project and on facilities of collaborators taken as base prototypes;


– cross-checks of results obtained in the progress of the Project;
– assistance in commercial application of developments obtained in the course of the fulfillment of the Project;
– joint symposia and working seminars on the topic of the Project.

Reference.


1. “Hydrodynamic instabilities and the transition to turbulence”, edited by H. L. Swinney and J. P. Gollub. Springer-Verlag, 1981.
2. Atkhen K., Fontaine J., Wesfreid J.-E., Highly turbulent Couette-Taylors patterns in nuclear engineering”, 10th International Conference on Couette-Taylor flows. France, Paris, 1997.
3. Drozdov S.M. The patent of Russia N2186615: ”Rotor mixer for liquid media”.
4. Drozdov S. M. “Numerical research of the modified Taylor flow. Development of the new concept of the industrial mixer.” 12th International Conference on Couette-Taylor flows. USA, Evanston, 2001.
5. M. Rafique, S. Skali Lami “A study of steady state flow in modified Taylor-Couette system: Inner rotating wavy cylinder coaxial with a smooth stationary outer cylinder”, 11th International Conference on Couette-Taylor flows. Germany, Bremen, 1999.


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