论文部分内容阅读
Distillation plays an important role in chemical process industries and consumes a considerable amount of energy with an estimated 3% of the world’s energy requirement.Motivated by this large energy requirement for distillation,researchers have developed a range of column arrangements that can bring savings in both energy and capital cost.Any decrease in energy requirement will have both economic and environmental benefits in terms of the reduced use of fossil fuels and associated emissions.A side distillation column is widely used to separate multicomponent mixtures into three products[1].However,this kind of column consumes considerable amounts of energy due to thermodynamic restrictions and the nature of the distillation process.Retrofit of the side distillation column to a dividing wall column (DWC) can result in significant energy savings.In general,a retrofit project in the distillation process covers a broad range of modifications and utilizes existing process ranging from only a simple modification or replacement of column internals to large modifications of the column configuration,partial enlargement of the shell diameter and height,and the modification of auxiliary equipment.In any case,the key to a successful retrofit lies in exploiting the existing hardware by maximizing the use of existing equipment while,at the same time,minimizing the need for new hardware to minimize the capital cost[2].This study evaluated a systematic method for optimal retrofit of a side stream column to a DWC.The side column is modified by adding a wall in the middle section whilst maintaining the same number of trays.The minimum energy requirement for the separation of a multicomponent mixture was used for a feasibility study.The initial DWC structure design involves applying a shortcut design procedure based on a conventional column configuration[3,4].After determining the preliminary ranges of the variables through single-factor testing,a Box-Behnken design was used under the response surface methodology[5] to determine how the variables interacted and optimize the system in terms of the reboiler duty.The simulation data was fitted to a second-order polynomial model and the regression coefficients were obtained.One case study was illustrated to demonstrate the proposed methodology.The results showed that the optimal retrofit of a side distillation column to the DWC could not only save a significant amount of energy,but also increase the capacity.This study highlights the potential for retrofitting a side stream column to a DWC from a techno economic point of view.