| Reactive distillation is a typical process intensification technology of chemical engineering. It combines reaction and separation in a single column. Internally heat integrated reactive distillation column (HIRDiC) applies the conception of internal heat integrated distillation (HIDiC) column to the reactive distillation column. HIRDiC divides conventional RD column into two insolated columns which are operated under two different pressures, the heat exchange between two columns takes place on the shells or the heat panels. Because of the efficiently energy saving by the means of internal integration, this technology dramatically lowers the energy consumption and the economic cost of the whole system. In this article, a new method of designing the HIRDiC which is based on the hydraulic analysis is presented, and a HIRDiC applied for the hydration of EO is designed as an example.(1) A method based on the hydraulic analysis is presented to design HIRDiC. First of all, the conventional RD column is analyzed, and then the reactive section and the stripping section of the tower are separated into two insolated towers. After the separation, the distribution of the temperature is analyzed, and the thermodynamic feasibility analysis of the internal heat integration is conducted at the same time.Then an appropriate configuration of the HIRDiC is chosen and then based on configuration of the column and the heat design method, the internal heat integration amounts is calculated. In the light of the heat integration amounts, an internal heat integrated column is simulated. Then the physical space of the column is studied to examine the the hydraulic feasibility of the system. If the system is infeasibility in hydraulics, the configuration of the column or the heat exchange amounts between the sections can be adjusted until the whole system is hydraulic feasible, so that the design of the heat integrated reactive distillation column can be finished.(2) A concentric HIRDiC and a multi-tube HIRDiC are designed for EO hydration based on the developed method.Firstly, a concentric HIRDiC is designed based on uniform heat distribution for the EO hydration with the goal of ideal heat integration which means reboiler duty reaches zero. An analysis of the temperature is conducted and it turns out that the column is thermodynamically feasible. Then the hydraulic feasibility analysis of the concentric ideal HIRDiC is proceeded and the result shows that the physical space in the column is insufficient to provide the heat exchange area for the heat integration due to the large amounts of the heat transfer energy, in other words, concentric ideal HIRDiC is infeasible in hydraulics. Then the hydraulic infeasibility is solved by declining the amounts of heat transfer energy after studied the effect of the heat transfer energy amounts on the parameters of the column. Consequently, a concentric partial HIRDiC is designed base on the maximum internal heat integration in condition of the feasible hydraulics. It can save more than 29% energy compared to conventional RD column.Secondly, a multi-tube partial HIRDiC is designed. On the basis of a feasible thermodynamic and hydraulic design, the multi-tube partial HIRDiC of the EO hydration needs 41 towers with 0.40m in diameter placing inside the stripping section in parallel to save 13.5% energy compared to conventional RD column.Last but not least, an economic evaluation among the conventional RD column, the concentric partial HIRDiC and the multi-tube ideal HIRDiC is performed. In a results, the multi-tube column is slightly cheaper to the concentric column and both of them can save about 63% TAC compare to the conventional RD column.The method that this article developed can provide theoretical guidance and model support for the design and optimization of the HIRDiC, especially for those which is designed based on the hydraulic feasibility analysis. |
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