Integrated processes such as reactive distillation offer the potential for reduced capital and operating costs compared to conventional flowsheets. In this work new tools for the identification of the optimal reactive distillation process with the optimal degree of integration are developed. A conceptual design method based on the boundary value method is used for a set of reactive distillation processes. The combination of a reactive distillation column with a pre-reactor is a valuable alternative to standalone reactive distillation columns. This thesis presents an approach to identify promising designs for such flowsheets and the optimum distribution of the reaction extent between the pre-reactor and the reactive distillation column. The methodology uses a boundary value method for the design of the column; chemical equilibrium is assumed. The column usually consists of a reactive `core', two rectifying sections and one stripping section. This work presents an approach to identify promising designs for standalone reactive distillation columns as well as for reactor - reactive distillation column flowsheets, when reaction kinetics are available. Reaction kinetics are considered and several near-optimal flowsheet designs are generated. A new approach for the conceptual design of double-feed reactive distillation columns is presented. One of the feed streams is situated at the boundary of the reactive section and the other one can be fed into the non-reactive section of the column. Thus the column consists of an additional separating section, which offers the opportunity to add an additional function to the column. The production of methyl acetate is an example for such a column structure. The additional section in that case acts as an extractive distillation zone. Here also chemical equilibrium is assumed. The integration of further separation steps with a reactive distillation column leads to a highly integrated process: a reactive dividing wall column. Within one apparatus, more than two products can be obtained and the capital cost can be reduced drastically. Furthermore, the well-known reduction in energy demand for dividing wall columns compared to a sequence of conventional distillation columns can lead to reduced operating costs. However, the simulation, design and operation of such complex columns is complicated. A novel approach for the conceptual design of reactive dividing wall columns is presented in this work. Chemical equilibrium is assumed on every reactive stage of the column. The use of the concept of product regions and composition manifolds during all proposed design procedures leads to an increased robustness when compared to conventional approaches based on BVMs. Furthermore, the approaches can be used for n-component systems. Several column designs with different design and operating' parameters are identified for each reactive distillation process, allowing the process engineer to compare and choose from a selection of designs. These tools can assist in identifying the optimal degree of integration for reactive distillation processes ranging from reactor - reactive distillation combinations via complex double feed reactive distillation columns with additional separating sections to the most integrated reactive distillation process: the reactive dividing wall column. The new methodology offers an easy to use tool for process engineers, which assists in identifying an economical integrated reaction-distillation process and could lead to increased industrial applications of technologies coupling unit operations.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:503083 |
| Date | January 2006 |
| Creators | Daniel, Guido |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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