Working Party on Mixing of the European Federation of Chemical Engineering (EFCE-WPM)

European Federation of Chemical Engineering
Working Party on Mixing

MINUTES `97

of the Meeting of the Working Party on Mixing of the European Federation of Chemical Engineering, held on the occasion of the 9th European Conference on Mixing in Disneyland Paris Convention Center, Marne-la-Vallée (France) on March 20th, 1997.


Minutes of the Meeting of the Working Party on Mixing (WPM) of the European Federation of Chemical Engineering, held on the occasion of the 9th European Conference on Mixing in Disneyland Paris Convention Center, Marne-la-Vallée (France) on March 20th, 1997.

Place of Meeting: Hotel New York
Duration of the Meeting: from 6:45 pm to 8:45 pm

1. Present 2. Excused:
a) WPM Members b) Invited:
BelgiumProf. M. Bruxelmane FranceMrs. M. Poux
Dr. C. Xuereb
GermanyProf. A. Mersmann
BulgariaDr. S. D. Vlaev GermanyProf. M. Kraume Great BritainMr. K. J. Carpenter
Czech RepublicProf. P. Ditl
Dr. I. Foøt
Great BritainDr. R. King
Prof. A. W. Nienow
IsraelProf. D. Wolf
FranceDr. J. Bertrand IsraelDr. L. Braginsky LatviaProf. U. Viesturs
GermanyProf. F. Liepe JapanProf. K. Takahashi The NetherlandsProf. L. L. van Dierendonck
Great BritainProf. J. M. Smith SloveniaDr. A. Bombac PolandProf. F. Strek
HungaryDr. J. Gyenis USAProf. P. M. Armenante SloveniaProf. M. Zumer
ItalyProf. G. Baldi
Prof. F. Magelli
RussiaDr. V. Barabash
The NetherlandsProf. H. E. A. van den Akker USAProf. E. B. Nauman
SwedenProf. A. Rasmuson
SwitzerlandDr. W. Tauscher

Prague, June l0th, 1997

I. Foøt
EFCE-WPM Secretary


AGENDA

  1. Adoption of the Minutes of the WPM Meeting held in Prague (Czech Republic) on August 28th, 1996
  2. Activities of the WP on Mixing of the French Society of Chemical Engineers (GFGP)
  3. Activities ofthe Fluid Mixing Processes Subject Group of the Institution of Chemical Engineers
  4. Activities of the Conference Committee within the EFCE-WPM
  5. Experimental Standards for Measurements ofVarious Quantities in Stirred Tanks
  6. Setting up Awards Committee within the EFCE-WPM
  7. The 16th NAMF Mixing Conference
  8. WPM Eventin l998
  9. The l0th European Conference on Mixing
  10. Miscellaneous
1: Adoption of the Minutes of the WPM Meeting held in Prague (Czech Republic) on August 28th, 1996.

No amendments were requested. The Minutes were approved and adopted.

2: Activities of the WP on Mixing of the French Society of Chemical Engineering (GFGP)

Dr. J. Bertrand (Chairman of the WPM of the French Society of Chemical Engineering -GFGP) presented a report on the recent activities of the WP on Mixing of the French Society of Chemical Engineering. The delegates discussed this report and expressed their warm thanks to the French WPM for preparation and organization of the 9th European Conference on Mixing. Delegates appreciated above all the role of Dr. Bertrand as a Chairman of the Organizing Committee of the Conference and they remembered an outstanding role of a Chairman of the Scientifíc Committee of the Conference Prof. J. Villermaux ceased on February 24th. Main points of the report are summarized in Enclosure 1.

3: Activities of the Fluid Mixing Processes Subject Group of the Institutions of Chemical Engineers.

Prof. J. M. Smith (Chairman of the FMPSG of the Institutions of Chemical Engineers) presented a report on the recent activities of the Fluid Mixing Processes Subject Group of the Institution of Chemical Engineers. The delegates discussed this report and appreciated an organization of the Symposium "Mixing and Reaction" (January 9th, 1997) in Birmingham in recognition of Professor J. R. Boume, to this outstanding contribution to the area of chemical reaction engineering. Main points of the report are summarized in Enclosure 2.

4: Activities of the Conference Committee within the EFCE- WPM.

Dr. I. Foøt a Chairman of the Conference Committee within the EFCE-WPM prepared a "List of Conferences on Mixing and Sessions on Mixing of the Conferences of Chemical Engineering in 1997" (see Enclosure 3). The delegates discussed the List and recommended to add into the List, if available, e-mail addresses of the Scientific Secretaries of the Conferences or Sessions. Prof. Ditl informed the delegates that the First European Congress on Chemical Engineering (Florence (Italy), May 4-7,1997) will not cover a Session "Mixing" to avoid an overlap with the programme of the 9th European Conference on Mixing (Paris (France), March 18-21,1997).

5: Experimental Standards for Measurements of Various Quantities in Stirred Tanks.

Prof. M. Kraume informed the delegates about the activities of the WPM of the GVC.VDI (Germany) to define experimental standards for measurements of various quantities in stirred tanks (see Enclosure 4). Delegates discussed the Report and confirmed necessity to standardize various experimental techniques for determination of the main quantities describing process of mixing; such activity seems to be very useful. Dr. R. King informed the Meeting about his effort to apply for special EU Project (Grant) "MIXNET" dealing with a Network for a harmonization of research methodologies and of standards to generate a better understanding of mixing and to promote communication between users of technologies, researchers and manufactures in Europe. The Network activities are shared between three clusters:

Submission for Proposal for four years implementation (1997 - 2000) has been made with description of the programme (three Clusters) and Clusters Coordinators. Final approval from the EU Commission is expected in June 1997. Then after nine months the final programme will be prepared. Funding of each participant is considered mainly for travel expenses (for each participant cca 18 k ECU / year). Professor A. Nienow mentioned that it is an important but extremely diffícult problem (e.g. technique for determination k1a coeffícient) its solution must be very careful. Prof. Ditl expressed his meaning that all the problems dealing with present absence of recommonded standards for measurement of quantities at mixing process come from nonexistence of the Research Committee within the EFCE-WPM and he invited the WPM delegates to consider a chairmanship of this Committee. He mentioned moreover, that the co-ordination activity of Dr. King is therefore very useful. Dr. King recommended to include some the German company into the Network. Dr. Foøt informed the Meeting about the German Conference on Mixing (May 26 - 27, Bad Margenthein) and expressed his hope that this proposal can be discussed during the Conference. Finally Dr. King informed the delegates that after the Project will be approved and Contract will be prepared regular Meetings of the Project participants will be organized approx. once per year according to the Clusters.

6: Setting up Awards Committee within the EFCE-WPM.

To promote research and scholarship by the recognizing members both of the EFCE-WPM and the national WPMs, who have made outstanding contributions to the field of mixing the proposal was made to establish Awards Standing Committee within the EFCE-WPM: Prof. J. M. Smith (Chairman), Prof. F. Magelli, Dr. W. Tauscher and Prof. L. L. van Dierendonck. Delegates supported setting up the Awards Committee and approved its Chairman as well as its members. Prof. J. Smith will prepare a programme and recommendation for the activities of the Committee for the EFCE-WPM Meeting in 1998.

7: The 16th NAMF Mixing Conference.

Prof. P. M. Armenante, Secretary of the NAMF informed the EFCE-WPM Meeting about the 16th Biennial North American Mixing Conference to be held in Williamsburg (VA, USA) in June 22 - 27, 1997. Totally 97 papers for the Conference is expected distributed into major plenary lectures, ordinary lectures and posters with a short oral summary of each paper at the poster session. Preliminary technical programme has been distributed during April 1997.

8: WPM Event l998.

Dr. S. D. Vlaev gave information about a Summer School of Chemical Engineering (to be a Registired Event of the EFCE) to be held in Varna (Bulgaria) during a week from May 11th. "Mixing Day" will be organized on May 15th. Summer Schools of Chemical Engineering have been organized more than least 20 years in special Congress Center in Varna at the Black Sea Coast. Usual number of participants is about 60. The Summer School consists of invited lectures (45 min) and regular oral (20 min) and paper presentations. Language of presentation is English. It is planned a Conference on mixing for the Summer School 1998. Expected expenses for participants (full board acommodation, meals and Conference Fee) are for one week stay (whole Summer School) approx. 550.- ECU and for three days stay (Conference on Mixing) approx. 200.- ECU. There are direct plane connections (flights) from the main centres in Europe to Varna. The delegates present discussed the proposal to organize next EFCE-WPM Meeting on the occasion of the above mentioned Summer School and they expressed their agreement with proposed date and place of the Meeting. Details of the above mentioned proposal are summarized in Enclosure 5.

9: The 10th European Conference on Mixing.

Prof. Van den Akker presented report about the date and place of the l0th European Conference on Mixing (see Enclosure 6). To avoid an overlap with the "Conference" ISCRE 2000" the term of the Conference has been shifted for term: July 2-5, 2000. Conference Proceedings will be available for the Conference participants at the beginning of the Event Delegates discussed the proposal and approved date and place of the l0th European Conference on Mixing.

10: Miscellaneous.

Dr. W. Tauscher made a proposal to renew at the EFCE-WPM Meeting in 1998 discussion about "Recommended Symbols, Terms and Units in Mixing" within Europe. Dr. Foøt will include this Item to Agenda of next EFCE-WPM Meeting with a short explanations of the problems avoiding an approval of the final version of the Proposal made 15 years ago. Dr. J. Bertrand will inform the EFCE Science Advisory Board at its meeting, to be held in Florence (Italy) in May 1998 on the ocassion of the I-st European Congress on Chemical Engineering on behalf of the EFCE-WPM Chairman about recent activities of the WP on Mixing of the EFCE. Prof. K. Takahashi, Chairman of the WP on Mixing of the Japanese Society of Chemical Engineers presented a short information about its activities. The WPM in Japan was set up 25 years ago by Prof. Sh. Nagata; Anniversary of this Event was celebrated at the last WPM Meeting. Regular WPM Meetings are organized once per year and strong effort has been made to set up the Asian WP on Mixing (Japan, Taywan, China, etc.). Prof. Takahashi will inform the EFCE-WPM every year at its Meeting about the Japanese WPM. Prof. Ditl informed the Meeting that next (13th) Intemational Congress CHISA will be held in Prague in August 1998. Shorter (two years) interval has been chosen to avoid an overlap with European Congresses of Chemical Engineering (next Congress will take place in 1999 in France).


Report on the activities of the French Working party on Mixing

The French Society of Chemical Engineering (Groupe Francais de Génie des Procédés) proooses to its members 8 thematic working parties. 1 chair the working party on mixing which is one of them. The aim of this group is to enable users, academic researchers arid manufactures to regularly meet in order to debate about industrial mixing problems, to inform them about recent advances in this field and to point out the rnain attempts necessary to make in priority.

In 1996, the topic of CFD appeared to be of general interest. As usually in this working party, the meeting has been organized near a manufacturer of mixing equipment. This year, it was near Lyon and LUMPP company. The one-day meeting (November, 27) has been a success with 65 participants and among them more than 70% of people from industries and manufactures who gathered around the theme "Numerical tools in industrial mixing service".

During this meetins, discussions have been initiated around invited oral presentations through which home or commercial softwares have been presented.

Isabelle Naude (Laboratoire de Génie Chimique, Toulouse) has proposed some results obtained with FLUX, a home software very simple to use, able to help manufacturers to choose the right agitators and their positions in vessels operating in the laminar flow regime.

Then, the Pr. Philippe Tanguy has spoken about POLY3D which has been elaborated in his group. Concerning the 3D mixing of non-newtonian' fluids, this software is able to take into account through a virtual representation the geometrical complexity of agitators generally used in this kind of fluids.

The following oral presentation has been given by the Pr. Alain Liné (INSA, Toulouse) about the possibilities to predict gas-liquid flovvs. He pointed out the difficulties and limits encountered in this fíeld, the experimental comparisons to be done and seized the opportunity to present some interesting results obtained with a Particle Image Velocimeter.

Some examples of the possibilities by numerical simulations achieved with FLUENT in agitated tanks have been presented by the Dr. Catherine Xuereb (Laboratoire de Génie Chimique, Toulouse). conitinuous and batch reactors, direct simulation' of impeller design with non-structured meshes, particles tracking, etc. The limits of such computations have also been pointed out.

The Dr. Laurent Falk (Laboratoire des Sciences du Génie Chimique, Nancy) has drawn attention to the difficulties encountered in the integration of chemical reaction aspects in the CFD.

A very interesing visit of LUMPP company followed the lunch. Then, after a presentation by Pierre Henric (Rayneri Society) about the evolution of the profession of manufacturer during 30 years, an open discussion enabled the industrial participants to express their needs and expectations in CFD.

The great interest of numerical tools is clearly appeared along the meeting. Nevertheless, the following limits have been underlined:

  • be careful of too rapid interpretations of precise CFD results; experimental comparisons must always be possible to achieve
  • softwares need a good scientific background of their users; this is a condition rarely satisf'ed in small manufactures which typically employ less than 50 persons. In these cases, going into partnership with laboratories belonging to universities seems to be the best choice.

    At last, it has to be pointed out that the major part of the participants to this one-day meeting gathered again at the 9th European Conference on Mixing in Paris. For many of them, it was the first time they could assist to such an intemational scientific congress, and certainly not the last one.


    Joël BERTRAND
    Chairman of the French Working Party on Mixing

    The Institution of Chemical Engineers Fluid Mixing Processes Subject Group (FMPSG)

    Report of Activities
    The group has about 100 subscribing members drawn from industry and academic institutions. It is not necessary to be a member of I.Chem E. to belong to the FMPSG.

    During the last year there have been four succesful meetings. A two-day symposium in the series "Fluid Mixing" (No. 6) was held in Bradford. About 70 attended with a few coming from outside the UK. It is probable that the next Symposium in this series will be held in 1999. Another meeting was organised, jointly with the Water S.G., this time in Leeds. Future cooperation with this group is planned - probably another joint meeting in two or three years time.

    A student competition attracted seven entries presenting current research work. This meeting was held in Birmingham with about 40 attending. The winning paper was presented subsequently at the AIChE Annual Meeting in Chicago, November 1996, with the attendance of the competition winner subsidised by the FMPSG.

    The retirement of Professor John Boume was marked by a special symposium on Micromixing, held in Birmingham in January 1997. About 70 participants heard a full programme of lectures, including a review from Professor Bourne and presentations from colleagues and students as well as from industrial users of the technique he has evolved. He also received a plaque (from NAMF) and an engraved paperweight (from FMPSG) in recognition and appreciation of his work and contributions to mixing technology.

    Prof. J. M. Smith
    Guilford, Surrey, March 19th, 1997

    List of Conferences on Mixing and Sessions on Mixing of the Conferences of Chemical Engineering 1997

    1. IChemE Fluid Mixing Processes Subject Group Meeting "Mixing and Reaction", January 9, 1997, Birmingham (UK)
      8 papers (Main Speaker: Prof. J. Boume, ex-ETH Zurich)
      Scientific Secretary: Dr. W. Bujalski, The University of Birmingham (UK)
      e-mail address:
      mixing-reaction@bham.ac.uk
    2. 9th European Conference on Mixing, March 18-21, 1997, Disneyland Paris Convention Center, Marne-la-Vallée (France)
      34 oral papers and 51 posters
      Scientific Secretary: Dr. J. Bertrand, Technical University of Toulouse (France)
      e-mail address: joel.bertrand@ensigtc.fr
    3. Seminar "Ruehren und Mischen. Alte Probleme - Neue Losungen", April 21 - 23, 1997, Erlangen (Germany)
      21 oral papers.
      Scientific Secretaries: Dipl.-Ing. M. Schäfer, Dipl. Ing. P. Wächter, Lehrstuhl für Strömungsmechanik, Universität Erlangen - Nürnberg, Erlangen (Germany)
      e-mail addresses: mschafer@lstm.uni-erlangen.de, peter@lstm.uni-erlangen.de
    4. 11th Czech Conference on Mixing, May 19-22, 1997, Brno (Czech Republic)
      26 oral papers and 20 posters.
      Scientific Secretary: Dr. P. Seichter, TECHMIX, Ltd., Bmo (Czech Republic)
    5. Sitzung des Fachausschusses "Mischvorgänge" der GVC-VDI-Gesselschaft Verfahrenstechnik und Chemieingenieurwesen, May 26 - 27, 1997, Bad Marghenthein (Germany)
      20 oral papers.
      Scientific Secretary: Dr. Ing. P. Zehner, BASF, Ludwigshafen/Main (Germany)
    6. "MIXING XVI", 16th NAMF Biennial North American Mixing Conference, June 22 - 27, 1997, Willimsburg (VA, USA)
      62 oral papers and 35 posters.
      Scientific Secretary: Dr. R. R. Hemrajani, Exxon Research and Engineering Company, Florham Park (NJ, USA)
      e-mail address: ramesh.r.hemjarani:@exxon.sprint.com
    7. 7th Canadian Chemical Engineering Conference, October 5-8,1997, Edmonton (AL, Canada)
      Session on Mixing
      Scientific Secretary: Dr. J. H. Masliyah, Dept. of Chemical and Materials Engineering, University of Alberta, Edmonton (AL, Canada)
    8. 1997 Annual Meeting of the AICHE, November 16-21, 1997, Los Angeles (CA, USA) 6 Sessions on Mixing:
      1. Gas-liquid and solid-liquid mixing,
      2. CFD,
      3. Visceous mixing and mixing fundamentals,
      4. Mixing and fast reactions,
      5. Industrial mixing and scale up,
      6. Liquid-liquid mixing: Where should we be going?
      Scientifíc Secretary: Dr. W. R. Penney, Dept. of Chemical Engineering,
      University of Arkansas, Fayetteville (AR, USA), e-mail address: wrp@engr.vark.edu

    Report: Experimental standards for measurements of various quantities in stirred tanks German GVC-VDIO Working Group "Mixing Processes"

    Stirred tanks are used for various operations in practice:

    Throughout the last decades experimental results of several investigations have been published. Comparison and assessment of these data is often nearly impossible as geometric parameters, experimental conditions, and measurement techniques differ noticeably. Different tank diameters lead to additional problems.

    For this reason experimental standards for measurements of various quantities were set by the German GVC-VDI Working Group ''Mixing Processes". Thereby reliable and accepted experimental results should be achieved under standardized conditions. They can be used

    Currently eight members of the working group coming from industiy and university carry out "circle experiments". A standard geometry and standard measurement techniques are used for these investigations which are done at different locations in Germany. In a following comparison of results discrepances will be determined and analysed. By this measurement techniques will be improved, consequences of geometric deviations resulting from production will be determined, and data scattering caused by the stirring system and the measurement techniques will be found out.

    The standard stirred tank is shown in fig. 1 with the main geometrie sizes. The tank diameter of 0,4 m was chosen as a compromise. Expenditure for chemicals should minimized. On the other hand scale-up of experimental results should be reliable which is not the case for smaller sizes. A Rushton turbine and a six blade 45°- pitched-blade-turbine (cf. fig. 2) are chosen as standard stirrers. These stirrer types can be used for nearly all operations in stirred tanks. In addition production of these stirrers can be done easily with high accuracy because of their geometry, which is not the case for propellers. The selected standard stirring system is not optimized for a special stirring operation but is used as a reference.

    In the following a short description is given of the different stirring operations which are investigated and the measurement techniques selected. So far experiments were carried out only with water. Liquids with higher viscosities migth be used later. For better comparison the different stirrer speeds were fixed for all experiments.

    1. Power number Ne
      Measurement method: not fixed; used: torsion shaft with strain ganges, electrically with eddy current torque transducers, torsion shaft, turning table.

      First results: Ne values differ up to approximately +/-10 % (Rushton turbine) or +/- 20 % (pitched-blade-turbine) from the mean values. The scattering is much less for every single run.

    2. Homogenization
      Measurement methods: mixing times are determined with two different techniques:
      a) chemical decolorization method using thiosulfate/iodine with starch indicator; 4 measurements per stirrer speed.
      b) conductivity measurement using NaCl solution; 10 measurements per stirrer speed.
      Feed location, probe position and mass of chemicals are standardized and mixing time is measured for 95 % degree of mixing.

      First results: decolarization method leads to larger scattering (+/- 20 %) of the n data around the mean value whereas the conductivity method results in a scattering of about +/-10 %. Sometimes greater discrepances appear. The mean values n determined using both methods are in a good agreement.

    3. Suspension of particles
      Glass beads of two size fractions are used a) dp = 0,15 - 0,25 mm, b) dp = 0,8 - 1,2 mm
      Measurement method: visual observation.
      Suspension criterion
      a) complete off-bottom suspension using a lower and an upper 1 s - criterion
      b) 90 % suspension height

      First results: heterogeneous results which depend on the particle size. Sometimes good agreement of suspension stirrer speeds, sometimes discrepances higher then a factor of 2.

    4. Dispersion in gas/liquid systems
      a) Flooding point: determined by visual observation and by torque measurement
      b) Gas hold up: determined by measurements ofthe liquid level
      c) Mass transfer: measurement method will be chosen.

      First results: none, the measurements are carried out currently.

    Prof. Dr.-Ing. M. Kraume

    INFORMATION
    about the next WP-MIXING session

    to be held in Varna on the occasion of the 8th Intemational Summer School of Chemical Engineering

    My report concentrates on the following issues:

    1. The 8th International Summer School - an event organised by the Bulgarian party of CEng Science
    2. The EFCE-WPM session at the Summer School
    3. Presentations
    4. Expected prices, Economic options

    1. The Intemational Summer School of Chemical Engineering is an event organised by the Bulgarian Academy of Sciences Institute of Chemical Engineering and the Bulgarian Sociefy of Chemical Engineering, to promote science and invention activities among chemical engineers in science and industry. The 1st School was organised in 1973 and the last one (the 7th one) was organised in 1995. The Event takes place in a seaside resort near the town of Varna (500 000 Inh.). Generally full board if arranged. Normally the School takes a week. The 9th School is expected to start on May 11th, 1998.

    2. The EFCE-WPMixing Sessíon for 1998 will be arranged either in the School Audience or in another place in a nearby hotel. In the letter case, free transport will be ensured by the organiser. It is noteworthy that the School includes lectures of all kinds of unit operations and equipment and NOT ONLY MIXING. Members of the WPMixing wishing to attend only a mixing session will be given the opportunity to stay only three days (two nights) in the School premises by an appropriate programme arrangement (e.g. a MIXING DAY on Thursday and/or Friday) by the end of the lecture week.

    3. Three categories of presentations are planned, i.e. lectures (40 min), shorter presentations (15+5 min) and poster reports. The present economlc sltuation In Bulgaria will not allow reimbursement of lecturers expenses, what was the usual practice before. Thus, lecturers are expected to appear from groups having research and information contracts with the Bulgarian Academy; volunteers are also welcome.

    4. Expected prices:
    Because of the volatile economic basis nowadays, only a rough estimate is given which is (full board):
    ECU 200/250 for a 3 day (knight) stay
    ECU 400/450 for a 7 day(6 night) stay

    The airport of Port Varna is an international one and many companies have direct flights to this town at the Black Sea. Another town at the Black Sea which is 100 km away from Varna and has an international airport is Port Burgas. Flights to Sofia will need to be continued by domestic flights Sofia-Varna-Sofia, as the distance is 500 km.

    Sometimes it is less expensive to buy a holiday package trip to Golden Sands Resort near Varna using a charter flight and a nearby hotel. Such cases will be considered by the organiser separately based on the principle of mutual benefit.

    Dr. S. D. Vlaev
    Bulgarian delegate at the WPM



    European Conference on Mixing X

    2nd - 5th July 2000

    Aula Congress Centre
    Delft University of Technology, Delft
    Netherlands

    • 3 days of oral and poster presentations
    • no parallel events
    • a few invited lectures
    • some emphasis on advanced experimental methods
    • partners programme
    • social programme
    • hotel accommodation in Delft

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