Towards further internal heat integration in design of reactive distillation columns—Part II. The process dynamics and operation

Abstract

In the first paper of this series, it has been demonstrated that the capital investment and operating cost can frequently be reduced substantially through seeking further internal heat integration between the reaction operation and separation operation for a reactive distillation column involving reactions with highly thermal effect. In this paper, the dynamics and operation of the resultant reactive distillation system is to be examined, with special emphasis focused on the dynamic effect of the supplementary internal heat integration. It has been found that seeking further internal heat integration can sometimes improve process dynamics and lessen difficulties in process operation. This outcome stems from the refined relationship between the reaction operation and separation operation involved and is of great significance in tightening process design for a reactive distillation column containing reactions with highly thermal effect.It should, however, be pointed out that seeking further internal heat integration might also confine severely the flexibility of the resultant reactive distillation column due to the reduction of mass transfer driving forces. When encountering a sharp increase in the product specification that is more relevant to the supplementary internal heat integration, the process might show deteriorated dynamic performance and can even converge to an undesirable steady state where the economical advantages of the supplementary internal heat integration are lost totally. Therefore, some effective measures to increase the redundancy of the resultant process design have to be taken to deal with the side-effect during process development.