Trading-Off Reactive Distillation Column Design And Control Through Process Intensification

Reactive distillation column, which integrates reaction operation and separation operation in one unit, can not only decrease energy consumption but also cut capital investment. Because of potential energy saving potential and huge economical benefit, it is widely studied by many researchers and scholars in recent years.Although graphic method and heuristic search method can conduct the primary design of reactive distillation column, they did not find the optimum structure of reactive distillation column from the aspect of reaction operation and separation operation, and restrict the spread and application of reactive distillation column. According to the ratio between the thermal heat released by the reactions involved and the latent heat of the reacting mixture separated, our research group divided reactive distillation into three categories:reactive distillation columns involving reactions with highly, moderately and negligibly/no thermal effect. In terms of energy integration and mass integration principle, we summarized fundamental strategies for process intensification in reactive distillation column, and proposed a set of systematic procedures for process intensification in reactive distillation column synthesis and design. In order to test and verify the methodology proposed, a methyl acetate reactive distillation and an olefin metathesis reactive distillation column are studied. The results indicate that the intensified process can cut reboiler duty by 4.52% and 5.59%, respectively. Further more, the process capital investment can be decreased.When reaction operation shifts from external reactor to internal of distillation column, relationship between reaction operation and separation operation can be strengthened. Although it can reduce operating cost and capital investment, the complexity of process is also reinforced, so distributing reactive section is a key factor for tradeoff between reactive distillation system design and control. In this paper, balance of design and control is investigated for an olefin metathesis reactive distillation column through four designs with different reactive section distribution. It has been demonstrated that the static performance can be improved with no necessary loss in process controllability and this outcomes confirm that reactive section distribution could be an effective decision variable for trading-off process synthesis and design and process dynamics and controllability.Double feed operation can alter feed location of partially reactant substantially, and it can intensify the internal integration between reaction operation and separation operation in reactive distillation. In order to investigate the impact of double feed operation on the reactive distillation static design and dynamic controllability, three processes, namely, ideal reactive distillation process, ethylene glycol reactive distillation process and 2-pentene metathesis reactive distillation process are studied. The results show that double feed operation can cut rebolier duty of reactive distillation column by 3.98%-18.3%, but make the process dynamic performance become sluggish simultaneously, so double feed operation also have a tradeoff impact on the reactive distillation column static design and dynamic responses.According to the ratio between the thermal heat released by the reactions involved and the latent heat of the reacting mixture separated, our research group divided reactive distillation into three categories. In terms of energy integration and mass integration, a set of systematic procedures for reactive distillation column synthesis and design are proposed. In order to test and verify the methodology proposed, a methyl acetate reactive distillation and an olefin metathesis reactive distillation column are studied. The outcomes confirm the validity of the proposed philosophy, which enrich the synthesis and design of reactive distillation column and promote the development of reactive distillation technology. Further more, reactive section distribution and double feed operation, two approaches for balancing design and control of reactive distillation column, can provide some meaningful guide lines, for intensifying reactive distillation column.