Dynamic Property Of A Reactive Distillation Column With Two Reactions: The Synthesis Of Isopropyl Palmitate

Reactive distillation technique is a novel technology to combine the reactive operation and separation into one unit. Compared to the traditional distillation system, not only simplifies the process, but it takes advantages in both economy and energy consumption aspects. This technique becomes a hot spot in chemical industry for the impressive accomplishments it achieving, economic and energy benefits are also proved by plenty of application examples successively used in chemistry. Thus, taking further research of reactive distillation shows great significance.Among a quaternary reaction system, if the reactants are the lightest and heaviest components according to the relative volatility rank, and the products have inner volatility, then we called it "hardest-separation system". For the sake of the reactants cannot gather in the middle of the column, traditional reactive distillation column cannot be applied in this situation. Hence, we proposed an innovative reactive distillation column with two reaction sections (RDC-TRS) to solve this problem.The structure placed the reaction sections both on the top and bottom of the column masterly. However, there will inevitably exist some inverse coupling on the top or bottom reaction sections for the system with thermal effect, which in turn affect the dynamic performance of the system.Isopropyl palmitate is an important raw material in chemistry, and widely used in many fields such as cosmetics and so on. Synthesis of isopropyl palmitate is a typical example of the "hardest-separation system". Based on this example, we designed a two-point temperature control strategy based on the basic model. For the purpose of figuring out the main factors that influence the dynamic property of RDC-TRS, we explore them from three facets:control the reflux tank level strictly, adjust the stages number of top reaction section and change the stages numbers of bottom reaction section. The result turn out that all these factors have great impact on RDC-TRS’s dynamic property. Thus, a compromise between steady-state design and dynamic controllability is further achieved.For the perspective to intense the integration of internal heat and energy, Thotla and Mahajan designed another RDC structure with an intensified single reaction section (RDC-ISRS). When faced feed flow and feed compositions disturbances, the target product’s dynamic response of RDC-TRS and RDC-ISRS shows that the structure of RDC-ISRS has better dynamic performance, whereas RDC-TRS shows better energy-saving ability. This result provides a direction for further research.