Abstract
The performance of industrial plants such as petroleum refineries, gas processing installations, etc. depends to a large extent on the operation of distillation columns which are considered as one of the most critical components, since they have a direct influence on the quality of the product.
The present work is mainly concerned with the performance of tray columns as well as the investigation of the effect of design parameters on their operation, focusing on downcomers which are very important elements in plate columns, because they ensure the passage of the liquid from one plate to the other as well as the degasification of the liquid in order to reduce the vapor entrainment. In fact a poor downcomer design may lead to flooding and hence a low performance of the column. Therefore it is proposed to study the effect of downcomers sizes on columns performance, finding the optimal dimensions which will ensure a satisfactory operation of the column.
First, the HYSYS software was used with actual data collected from a local refinery and concerning distillation columns, to obtain flowrate profiles, physical properties and compositions according to plates. The obtained results were used as input data for a Mathcad program elaborated to calculate values of certain parameters such as liquid residence time in downcomers, flooding, entrainment, weeping, liquid velocity, liquid load, and pressure drop, making it possible to control the downcomer operation. The obtained results for each plate were used to quantify and locate the problem in order to adapt an optimal solution. The developed program can be used for the control of similar plate columns, introducing just the operating conditions and real dimensions of the considered column.
