... with a GASOLFIN™ unit will be able to operate its FCC units in the most efficient mode: Maximum gasoline, followed by post conversion of FCC naphtha into propylene, butylene and BTX. The GASOLFIN™ unit will efficiently convert gasoline boiling range hydrocarbons including olefins, paraffins or naphthenes. These naphtha feedstocks are generally sourced from the FCC, Hydrocracker, Delayed Coker and Crude unit Light Straight Run (LSR).
A refiner wishing to increase propylene capacity generally has two options.
The first will be to use co-catalyst ZSM-5, in their FCC unit which maximizes propylene and butylene yields at the expense of naphtha production. Refiners may increase propylene yields from 4-6 wt% up to a maximum of approximately 12 wt%, assuming these refiners possess sufficient light gas handling capacities. Generally this is accomplished through upgrading the Wet Gas Compressor plus increasing the Distillation capacity of the FCC Product Recovery Section. Even minor capacity increases will generally require investments in excess of $25 million.
The second option will be to retrofit the unit to a high severity operation at a cost of $150 – $200 million.
A GASOLFIN™ unit is a viable option for those refiners wishing to convert a portion of the FCC naphtha stream into propylene. At an investment of approximately $100.0 million this unit will enable a refiner to process 10 KBPD of FCC naphtha into:
Propylene up to a yield of 28 wt%.
Butylene up to a yield of 20 wt%, which may be processed in the Alkylation unit to produce a premium gasoline blend stock.
Aromatics e.g. Benzene, Toluene and Xylene which may be sold as product or utilized as an additional blend stock possessing an average octane value of approximately 126 RON.
The zeolitic based catalysts currently employed in FCC units are highly efficient at producing gasoline. A refiner equipped with a GASOLFIN™ unit will be enabled to operate their FCC units in the most efficient mode: Maximum gasoline, followed by post conversion of FCC naphtha in the GASOLFIN™ unit.
The GASOLFIN™ unit is also able to convert very low valued Light Straight Run (LSR) naphthas directly into light olefins.
Typical LSR naphthas contain a high percentage of normal pentane and isopentane. Normal pentane is a poor gasoline blend stock due to the very low octane value of 65.0 RON. Both normal and isopentane possess high vapor pressures which are often a limitation in gasoline blending operations. Direct conversion of these pentanes into light olefins represents a significant economic benefit to the modern high conversion refinery.
LSR is typically first processed in the Catalytic Reformer due to its very poor octane values. Processing of the pentane and hexane portions of the LSR in a GASOLFIN™ unit will free capacity in the Catalytic Reformer leading to significantly improved cycle lengths together with substantially improved refinery economics. LSR may be processed in a GASOLFIN™ unit with a propylene yield of up to 42 wt%.
Delayed Coker naphtha requires hydrotreating for the removal of sulfur, nitrogen and di-olefin contaminants followed by Catalytic Reforming to restore octanes. Processing Delayed Coker naphtha in a GASOLFIN™ unit will directly result in increased Naphtha Hydrotreater and Catalytic Reformer capacities. Delayed Coker naphtha may be processed in a GASOLFIN™ unit with a propylene yield of up to 28 wt%.
The GASOLFIN™ operation may be optimized for high aromatic yields or may alternatively be designed as an on-purpose aromatic process. Incremental aromatic yields for typical FCC naphtha’s are approximately 20 wt%. A GASOLFIN™ may be designed to produce up to 72 wt% aromatics. The BTX yields will consist up to 65 wt% BTX with the majority being mixed xylenes.