Molecular reconstruction of naphtha steam cracking feedstocks based on commercial indices

A new method for feedstock reconstruction of industrially important hydrocarbon fractions is developed using as input the analytically determined ommercial indices such as the average molecular weight, the specific density, theH/C-ratio, the paraffin, isoparaffin, olefins, naphthenes, aromatics PIONA) weight fractions and a set of ASTM boiling points. The method is based on Shannon’s entropy criterion and allows generating a molecular omposition of a naphtha fraction that meets all the boundary conditions set by the industrially available commercial indices. The most important omponents present in a naphtha fraction are selected as possible feedstock components. This approach is very fast because the optimization unction can be transformed from a nonlinear equation in the N mole fractions (N∼ 102) into a nonlinear equation in maximally 14 parameters, aking it very attractive for the petrochemical industry. A good correspondence exists between the simulated weight fractions and the actual nalytically determined ones provided that the specified commercial indices are sufficiently accurate. The feedstock module is implemented in a imulation package for steam cracking but can be used as a stand-alone tool too. The combination of these two simulation tools makes it possible to btain a good agreement between the simulated and experimentally determined product yields for a set of 50 pilot plant experiments with different aphtha feedstocks under widely varying operating conditions. 2006 Elsevier Ltd. All rights reserved.