Increasing Refinery Product Slate Flexibility via revamping the Cat Feed Hydrotreater

Since 2005, the demand for mid-distillates from U.S. refiners has increased steadily to current production levels of 6.8 MMBPSD. This has been mainly a result of two market conditions: a feedstock advantage over international refiners thanks to the Tight Oil boom and increased demand from South America. As a result, many U.S. refiners are shifting their diesel to gasoline ratio to favor mid-distillates. However, as seasonal product spreads favor gasoline during the summer driving season, product slate flexibility is key for year-round profitability.

Revamping to Cat Feed Hydrotreaters (CFHT) to mild hydrocracking (MHC) service can provide this product slate flexibility while further increasing the quality of the FCC feed, thus benefitting overall liquid yields. In most cases, vacuum gasoil conversions in the range of 30-40% can be achieved in existing units with minor modifications to the reaction section. New product fractionators are typically required in order to separate the cracked distillates while also allowing the refiner to recover the mid-distillate boiling material found in most CFHT feeds. The resultant overall apparent net conversion is typically 40-50%. During periods of high gasoline margins, the Unit can be run in a low-conversion mode to maximize FCC feed rate and gasoline production.

This paper will present case studies, commercial experience, catalyst developments, and economics highlighting the benefits of the concept.