Experimental Verification of Equivalence of Qualities of Mixing for Physical Mixing to Unreacted Fraction for Instantaneous Reaction in Stirred Tank Reactor

Abstract

The relation of the degree of deviation defined by a first-order centered moment of concentration and the degree of standard deviation defined by a square root of variance of concentration of fluid, to the unreacted fraction for instantaneous reaction under unity of stoichiometric ratio was investigated both by experiments of physical mixing and chemical reaction performed at lower Reynolds numbers in a baffled stirred thank with turbine impeller, and by a theoretical study with use of a simplified mass exchange-type model. In the physical mixing experiment, a number of local concentrations were measured in the course of mixing between potassium chloride solution and distilled water stratified in two phases due to a slight difference in density, and the degree of deviaion and the degree of standard deviation were calculated. In the chemical reaction experiment, a number of concentrations of product were measured in the course of instantaneous reaction between acetic acid solution and ammonium hydroxide solution stratified in two phases due to a slight difference in density, and a mean unreacted fraction was calculated. It is found from these experiments that the degree of deviation is almost the same as the degree of standard deviation and, at the same time, agrees with the mean unreacted fraction within 3% experimental error. This experimental result is shown to be almost fully explained by the simplified mass exchange-type model.