OP-II-3

PP-II-22PARAMETERS OF MASS AND HEAT TRANSFER IN FIXED-BEDCATALYTIC REACTORS: ON THE QUESTION OF ITS THEORETICALPREDICTIONSKuz’min A.E.Topchiev Institute of Petrochemical Synthesis RAS, kuzmin@ips.ac.ruLet is consider a mathematical model of common catalytic reactor element(cylindric tube) with fixed bed of catalyst granules and, in general, more than onefluid flow (trickle-bed as common example). For closure of mass, momentum, heatenergy balance PDE (or ODE in simplified models) system one must know afunctional set of parameters - apparent reaction rate constants, coefficients ofintraphase (effective diffusion, heat conduction etc.) and interphase (for flow/catalystand flow/wall boundaries among them) transfer. For such a parameters one canapply dimensional analysis and obtain an equation liken1n= ∑i 2iNmrCiNmd1 Nmd2...(1)iwhere theory can define clearly only a “basis” of determining dimensionless numbersNm d1 , Nm d2 etc.; for value definition of C i and n i one, as it is thought to be, must carryon a set of experiments at various conditions. As a rule, it deliver a huge, sometimesinconsistent data array that often can not be satisfactory described by only onecorrelation like (1) with one set of C i , n i etc. for overall conditions range. Such aprocedure must be fulfilled for any of required numbers Nm r (where a correspondingcoefficient of a balance equation is included); a huge body of various papers isdedicated and was dedicated to these problems through decades. Is it possible toovercome tradition and to develop an alternative way for full determination ofequations like (1) (or more complex) with a minimum set of experiments?One can assume that a complex process taking place in a reactor (or in any otherapparatus of chemical engineering) represents a hierarchical three-level structure:the first level – one of atomic-molecular-scale motions, the third – one of reactorscalemotions (level of balance ODE), and the second one represents a motions atany intermediate scales (turbulent vortices, film flows, bubbledestruction/coalescence, local by-passes and dead zones etc.). Then, one canimagine an extremely idealized situation where a second-level motions does notexist, i.e. a reactor model coefficients are determined only by molecular-scale372