COMPUTER EVALUATION OF DISTILLATION PROCESSES WITH PARALLEL STREAMS

Mathematical models and iterative methods are developed for simulating alternative multicomponent distillation processes with parallel flow streams (vapour and liquid streams) in order to study the variation of separating effects. In the parastillation process, the uprising vapou r stream is divided into two equal parts at the bottom of the distilla tion column and the whole amount of the falling liquid is stage-by-sta ge alternatively contacted with both parts of the vapour. In the metas tillation process, the falling liquid is separated into two equal part s at the top of the column, while the whole amount of the uprising vap our is stage-by-stage alternatively contacted with both liquids flows (Fig. 1). According to our previous study 161, the parastillation proc ess results in smaller column with less investment or operating cost t han distillation. In this study the metastillation process is investig ated and it is found that the required theoretical number of stages in creases roughly by 50 %. However, the following liquid and vapour patt erns on the trays, as specified by Lewis [5], can change significantly the stage efficiency as well as the economics of the alternative proc esses.