Abstract
Around the globe, refiners are seeking to convert an increasing portion of existing Hydroprocessing capacity to process renewable feedstocks. Facilities face economic pressure to bring renewables production online quickly, in order to take advantage of the current government incentives (credits) for renewable fuels. Simultaneously, however, materials and corrosion engineers face a lack of data-based guidance regarding the appropriate materials selection and expected damage mechanisms for renewables processing units. This paper discusses many of the major damage mechanisms which are considered most relevant in different areas of the RDU - Renewable Diesel Unit (e.g., feed, hot effluent, cooled effluent, etc.). Significant attention is devoted to fatty acid corrosion in the feed system, and lower-temperature aqueous acid corrosion in the cool effluent system. Specific considerations must be made when an existing unit is converted into an RDU, compared to new construction. The source and precise blend of renewable feeds and the extent (if any) co-processing with conventional petroleum feeds impact the susceptibility to certain damage mechanisms throughout the unit. Upstream pretreatment processes can have unique implications on the expected corrosion in the RDU.
