Continuous stirred tank reactors: Designs for maximum conversions of raw material to desired product. Homogeneous reactions

It is shown in a series of illustrative examples how the conversion efficiency of many reactions can be markedly affected by the type of reactor used, even though the temperatures, catalyst, and basic kinetics are already fixed by the chemistry of the process. For such purpose graphical and analytic criteria are developed which permit the selection of a continuous stirred tank or tubular reactor system to obtain the most advantageous conversion of raw material to desired product. When a continuous stirred tank reactor process is preferable, the optimum number of reactor stages for maximum conversion is one. An example is given of a case where a combination of a continuous stirred tank and a tubular reactor is advantageous. A new graphical method of reactor design for simple or complex reactions is also introduced. This method utilizes continuous stirred tank reactor data directly rather than batch data or kinetics analyses. Reactions are classified according to the kinetic and stoichiometric characteristics which determine the allowable design procedures and the differences in the compostions paths occurring in batch, tubular, or continuous stirred tank reactors. The mathematical analysis of continuous stirred tank reactor systems for complex reactions leads to a set of difference equations. For cases of zero- or first-order reactions these are readily solved as illustrated in examples, even when several independent components influence the reaction kinetics.