Andrew McCord - Carolina Filters, Inc.
A major Houston area refinery operating a Solvent Deasphalting (SDA) unit, using purchased FCC Slurry oil as a feedstock, began having issues with blowback filtration units used in the process when the purchased FCC SO had varying solids content. The refinery approached the filter manufacturer to assist in resolving filtration issues which were assumed to be associated with off-spec feedstock. On-stream filter life had decreased from an expected 70+ days to 30 days or less.
The manufacturer obtained filter cartridges for dissection and filter media for contamination studies. Along with investigating the fouling events, the type and level of filtration were reviewed and found to be sufficient for the application.
Analyses showed that contamination was a result of asphaltene precipitation, various inorganic salt deposits such as iron sulfides, and residual chemicals remaining from traditional metallic filter cleaning methods. Micrograph pictures found the material embedded throughout the media matrix.
In order to remove the material, special cleaning techniques were required that addressed the various contaminants with attention to the location of the residuals.
Carolina Filters worked with both the Refiner and Filter Manufacturer to develop a Physical/Chemical Cleaning process (PCC) that allowed for chemical conversions of contaminants to soluble forms and a mechanical process that forced movement of residuals out of the media. To determine the degree of contaminant removal, a special pressure testing method was performed that provided the end-user with measurable metrics related to the % Recovery of the lost porosity of filter media, also providing an indication of cleaned filter start-up pressure drop.
Through collaboration with the filter manufacturer and the cleaning vendor, the refinery realized process improvement in terms of on-stream filter life – even with the poor feedstock. With acceptable feedstock, filter life is comparable to that of new filters.
Additional and unexpected benefits of the PCC process was the recovery of filters taken out of service due to the plugging of the media matrix where traditional cleaning was ineffective.
Through teamwork, it was found that the filter media was correctly specified and with appropriate cleaning, the media matrix could be cleaned and verified. It must also be noted that even with properly specified filter media design, feedstock greatly impacted the filter performance and the ability for traditional cleaning to remove the contaminant.
The presentation describes the results of the collaboration of Refiner, Filter Manufacturer, and Cleaning Vendor to resolve process issues and reduce operating and equipment purchase costs.