A new parallel competing reaction system for assessing micromixing efficiency—Experimental approach

Abstract Several kinds of methods can be used in order to study the state of mixing at molecular scale in stirred reactors. Conductometric and optical methods have not enough resolution. The aim of this work is therefore to propose a chemical reaction which acts as a molecular probe for assessing micromixing efficiency. A literature review shows that the number of available test reactions is limited. We propose a new system of parallel competing reactions A + B → R and C + νB → S whereby the state of micromixing in industrial reactors can be studied. The first reaction is a neutralization, the second one is the Dushman reaction between the iodide and iodate. We show that the formation of iodine (S) under the influence of an acid (B) in an alkaline medium (A) is a measure of segregation. This system makes it possible to study the influence of feed time, feed location and reactant concentrations on segregation. The method is validated by a study of mixing in standard stirred tanks of one and twenty litres. Scale-up rules are proposed.

[1]  J. Bourne,et al.  Mixing effects during the bromination of 1,3,5-trimethoxybenzene , 1977 .

[2]  M. H. Lietzke,et al.  The Equilibria and Kinetics of Iodine Hydrolysis , 1982 .

[3]  Laurent Falk,et al.  A generalized mixing model for initial contacting of reactive fluids , 1994 .

[4]  M. Kamiwano,et al.  Turbulent Mixing in a Tubular Flow Reactor , 1970 .

[5]  W. Ranz,et al.  Improved Conductivity System for Measurement of Turbulent Concentration Fluctuations , 1969 .

[6]  H. L. Toor,et al.  Second-Order Chemical Reactions with Turbulent Mixing , 1971 .

[7]  J. Bourne,et al.  KINETICS OF THE AZO COUPLING REACTIONS BETWEEN 1-NAPHTHOL AND DIAZOTISED SULPHANILIC ACID , 1985 .

[8]  Alice D. Awtrey,et al.  The Absorption Spectra of I2, I3-, I-, IO3-, S4O6= and S2O3=. Heat of the Reaction I3- = I2 + I- , 1951 .

[9]  Jerzy Bałdyga,et al.  The effect of micromixing on parallel reactions , 1990 .

[10]  John R. Bourne,et al.  Mixing and fast chemical reactionITest reactions to determine segregation , 1981 .

[11]  Chemical selectivities disguised by mass diffusion. V. Mixing-disguised azo coupling reactions. 6th communication on the selectivity of chemical processes†‡†§ , 1977 .

[12]  O. Miyawaki,et al.  CHEMICAL REACTIONS UNDER INCOMPLETE MIXING , 1975 .

[13]  An experimental investigation of the state of mixing of the fluid in a chemical reactor , 1970 .

[14]  A. Mersmann,et al.  Chemical engineering aspects of precipitation from solution , 1988 .

[15]  Edward L. Paul,et al.  The effect of mixing on scaleup of a parallel reaction system , 1992 .

[16]  J. Bourne,et al.  Some factors determining the critical feed time of a semi-batch reactor , 1991 .

[17]  W. Ranz,et al.  Concentration fluctuations and chemical conversion associated with mixing in some turbulent flows , 1970 .

[18]  K. T. Truong,et al.  Segregation effects on consecutive competing reaction in a CSTR , 1976 .

[19]  J. Bourne,et al.  Mixing effects in the bromination of resorcin , 1977 .

[20]  F. A. Holland,et al.  Liquid Mixing and Processing in Stirred Tanks , 1966 .

[21]  R. E. Rosensweig,et al.  Smoke-scattered light measurement of turbulent concentration fluctuations☆ , 1961 .

[22]  Jeanne Burbank,et al.  Atlas D-Equilibres Electrochimiques , 1964 .

[23]  Thomas L. Allen,et al.  The Formation of Hypoiodous Acid and Hydrated Iodine Cation by the Hydrolysis of Iodine , 1955 .

[24]  L. Eagleton,et al.  An experimental study of mixing and segregation in a stirred tank reactor , 1964 .

[25]  E. H. Dunlop,et al.  Investigation of the chemistry of a diazo micromixing test reaction , 1992 .

[26]  Micromixing Phenomena in Continuous Stirred Reactors Using a Michaelis-Menten Reaction in the Liquid Phase , 1978 .

[27]  A. Tobgy,et al.  Residence times, micromixing and conversion in an un-premixed feed reactor — II: Chemical reaction measurements , 1973 .

[28]  S. Nagata.  Mixing: Principles and Applications , 1975 .

[29]  J. Prausnitz,et al.  MIXING AND CHEMICAL REACTION IN TURBULENT FLOW REACTORS , 1965 .

[30]  Laurent Falk,et al.  A new parallel competing reaction system for assessing micromixing efficiency—Determination of micromixing time by a simple mixing model , 1996 .

[31]  Robert E. Treybal,et al.  Mixing and product distribution for a liquid‐phase, second‐order, competitive‐consecutive reaction , 1971 .

[32]  J. Klein,et al.  Interpretation of Experimental Liquid Phase Micromixing Phenomena in a Continuous Stirred Reactor with Short Residence Times , 1980 .

[33]  R. C. Weast.  Handbook of chemistry and physics , 1973 .

[34]  Shengyao Yu.  Micromixing and parallel reactions , 1993 .

[35]  A generalized two-environment model for micromixing in a continuous flow reactor—I. construction of the model , 1975 .

[36]  F. S. Manning,et al.  Intensity of segregation as a measure of incomplete mixing , 1964 .

[37]  Influence of Chemical Parameters on Micromixing in a Continuous Stirred Tank Reactor , 1975 .

[38]  M. Fournier.  Caractérisation de l'efficacité de micromélange par une nouvelle réaction chimique test , 1994 .