Propane Dehydrogenation and Steam Cracking: Heuristic Approaches to Plant Integration

The integration of propane dehydrogenation (PDH) and steam cracking by the combination of the olefin product recovery has been already studied in the early 1980s. While thermal cracking of ethane as well as heavier hydrocarbon feedstocks is still by far the main source of ethylene, catalytic dehydrogenation of propane to propylene has gained increasing market share in the recent past due to the highly attractive propylene selectivity. As both processes yield products of a similar nature, integration of both recoveries may appear simple and advantageous from total equipment point of view.

A more detailed analysis of bulk composition, trace components and operation requirements of each technology shows that combining of product recovery may result in a significantly more complex separation task compared to the individual separations. Rather than raising synergies in separation, both effluents bear the risk of “contaminating” each other. Moreover, process integration always adds complexity and possible undesired interdependencies.

This paper presents a more detailed study of integration potentials for PDH and steam cracking. Most important aspects regarding differences between cracked gases and PDH effluents are described. Related characteristics of different PDH technologies and their impact on integration scenarios are analyzed on a high level.

Some promising scenarios are derived, which focus on synergetic potentials of PDH and steam cracker integration, while possible risks from detrimental effects are avoided or minimized.

Finally, the paper outlines some properties from an existing plant, where a highly customized small-scale cracker and ethylene recovery process is integrated into a large-scale PDH. The design includes a substantially simplified cold section, which applies pressure swing adsorption technology, omitting the requirement of very low temperatures and matching or even exceeding olefin recoveries of conventional low temperature processes.