Reactive distillation design with considerations of heats of reaction

Although reactive distillation columns allow direct utilization of heat of reaction to separation operation, the effectiveness of internal heat integration appears generally to be unsatisfactory and their thermodynamic efficiency could quite often be improved substantially through seeking further internal heat integration between the reaction and separation operations. Prudent arrangement of reactive section, effective determination of feed location, and deliberate distribution of catalyst constitute the three methods that can complement internal heat integration within a reactive distillation column. The reactive section is suggested to superimpose properly onto the stripping section for exothermic reactions and onto the rectifying section for endothermic reactions. Feed location and distribution of catalyst should be determined so that the effect of internal heat integration can be maximized to its fullest extent. A sequential procedure is proposed to determine an appropriate process configuration for internal heat integration within a reactive distillation column. Five reactive distillation systems, involving not only equilibrium-limited but also kinetically controlled reactions, are used to evaluate the design philosophy proposed. It has been found that a substantial improvement in system performance can be achieved even for some reaction systems with side reactions and/or unfavorable thermodynamic properties. Seeking further internal heat integration has been demonstrated to be an effective method for refining process design of a reactive distillation column involving reactions with highly thermal effect. These conclusions are of great significance and can provide process designers with additional latitude to elaborate their process designs. (c) 2006 American Institute of Chemical Engineers