Optimization of Pre-Treatment Strategy in a Diesel Hydrotreater Retrofitted for Renewable Feedstock

With increased global demand for reduction of carbon emissions, renewable and bio-based fuel alternatives have become a technologically accessible option to offset traditional petroleum based fuels. Crude plant-based feedstocks, such as soybean oil, offer the advantage of enabling existing hydrotreater equipment to be retrofitted to produce chemically identical products to processed petroleum crude. Although these feedstocks offer a low barrier to entry into the renewable market, there are other challenges in the pre-treatment step that must be addressed. A west coast refinery recently converted an 8,000 BPD petroleum diesel hydrotreater (DHT) to process soybean oil feedstocks. Traditionally, a pre-filtration step was utilized to reduce particulate and free water load entering the DHT. Upon start up, operations personnel noticed increased rate of differential pressure build on the existing pre-treatment system while utilizing soybean feedstocks. Using field sampling and laboratory testing, key differences were noted between the petroleum and new soybean feedstock contamination profile. A solution was provided that allowed optimal run time and minimized influx of particles and free water into the DHT reactor bed. Based on the results observed in the field, guidelines and recommendations are provided for optimizing pre-treatment strategies during retrofit to renewable, plant-based feedstock.