Improving Plant Economics By Upgrading Low Value Hydrocarbon Stream By Enrichment of C9+ Compounds Using Divided Wall Distillation Columns

The shift towards lighter feedstock’s for Poly Olefins production, due to lower feedstock price and higher profit margin, has resulted in lower production of heavier aromatic fractions and in particular the C₉₊ fractions. As a result, over the last 5 years the supply of C₉₊ fractions has not catch up with increase in demand. Further, intense competition between petrochemical complexes has forced companies to retrofit plants for comprehensive utilization of all streams in the complexes for better operating margin. Among other things that are considered for up-gradation, enrichment of heavier hydrocarbons from the Pygas stream has been pursued intensely. In this work, the process intensification in C₉₊ stream enrichment from Pygas using non-conventional divided wall column structures is examined. The study is a first of kind to demonstrate the separation of bulk chemicals using divided wall columns. Further more, the studies indicated that by replacing conventional column sequence with the divided wall column structure, for a given product quality, a savings in the separation stages by 18%, energy reduction by around 32% can be realized.