Compare The Performance Between The RDC-TRS And The RDC-TBER Based On Parameter Analysis

For the process designs with reaction operation and separation operation, process intensification can enhance its design flexibility and thus greatly reduce the investment and operation costs. As a typical process intensification technology, reactive distillation has improved reaction conversion rate and reduced investment and operation costs as compared with the traditional process design by integrating the reaction operation and separation operation into one device.Despite the performance of reactive distillation is superior to the traditional process design, its advantages will change with the variation of internal conditions. For the reactive systems with the most unfavorable relative volatility ranking, i.e. the boiling points of the reactants are the lowest and the highest, the boiling point of the products are the middle ones, the conversion rate will be slow and the operation cost will be expensive because the reactants can’t be fully contacted. In order to suppress this problem, two structures, i.e. the reactive distillation column with two reactive sections (RDC-TRS) and the reactive distillation column with a top-bottom recycle (RDC-TBER), are proposed recently.Although the RDC-TBER has stronger internal mass and energy integration than RDC-TRS and can realize energy-saving, this advantage is likely to be reduced when the feeding and operating conditions change. Therefore, this paper aims to select the key parameters and comprehensively compare the static characteristic of these two process designs by changing the parameter condition. This paper studies hypothetical ideal exothermic reversible reaction which the boiling point’s ranking is the most disadvantaged, based on chemical equilibrium constants, relative volatility and product purity, and chooses the total annual cost (TAC) as objective function, searches for decision variables by grid search method to obtain the optimal structure and optimum operating conditions.The results show that the RDC-TBER has less TAC than RDC-TRS under different feeding and operating conditions. Especially when the change of parameter makes the system under unfavorable state, the more TAC will be saved. It indicates that the existence of external recycle can greatly improve the column’s internal mass coupling and energy coupling, which proves that the RDC-TBER has better applicability.