Claudia Maria de Lacerda Alvarenga Baptista

Chapter 3 Exploring FCC flexibility to produce mid-distillates and petrochemicals

Abstract FCC was traditionally designed to convert heavy gas oil range feedstocks to high octane gasoline. Brazilian refineries have relied on FCC as the chief conversion process. However, peculiarities of the local petroleum industry have forced refiners to change the FCC process, first to adapt to increasingly heavier feedstocks derived from national crude oils, and subsequently to change the product slate to comply with market demand, requiring less motor gasoline, more diesel oil and light olefins for petrochemicals. This paper will focus on the second set of process adaptations, including operating variables and choice of refinery processes schemes for low aromatics FCC products within crude oil choice constraints.

Feedstock effect on FCC catalyst stripping

The effect of feedstock on FCC catalyst stripping was investigated based on prototype FCC unit data from three different feedstocks: blend of heavy gas oil from vacuum distillation and delayed coking units, and two different atmospheric residues (paraffinic and with high carbon residue). The higher the feedstock crackability, the higher is the amount of strippable hydrocarbons. The average hydrogen-to-carbon ratio depends on the feedstock and is lower for the paraffinic ATR. The coke on spent catalyst samples was characterized for all feedstocks, indicating a much lower amount of CH 2 Cl 2 insoluble coke for the heavy atmospheric residue feedstock. The insoluble coke of the heavy ATR was also more alkylated and/or naphthenic than in the other feedstocks.