MODELING OF LIGHT NAPHTHA-HEAVY NAPHTHA OVERLAP USING CDU DATA FROM ASPEN PLUS

Abstract

The most expensive and important process in the petroleum refining and petrochemical industries is the distillation of crude oil. A crude distillation unit (CDU) consists of an optional pre-flash tower (PF) followed by atmospheric distillation unit (ADU) and vacuum distillation unit (VDU). The products from CDU are basically mixtures of various hydrocarbon compounds and it is not possible to characterize them in terms of individual components. The products from crude distillation unit is often characterized in terms of certain properties such as Reid vapor pressure for volatile products, flash point for light distillates, pour point for heavier fractions, etc. Measurement of these product properties are cumbersome and time consuming. In today's highly competitive market, a tight quality control is must. This can be achieved if the product properties can be made available online. In the present work, a model equation is developed to estimate TBP overlap for Light Naphtha and Heavy Naphtha that can be used to find product TBP by super-positioning overlap on feed TBP. For developing said correlation, data from Aspen PIusTM was used. The model equation is predicted by studying the effect of following parameters on product TBP and TBP overlap: 1. Reflux ratio 2. Number of stages between two product draw stages i.e., between Light Naphtha and Heavy Naphtha An analysis was also performed in order to compare the duration of time required to estimate TBP overlap for Light and Heavy Naphtha using the conventional resources like Aspen Plus iii software package with that required using the developed model equation. It was found out that the presently developed model equation is much faster than the conventional resources.