Sustainable aviation fuel (SAF) and renewable diesel (HVO) production simulation models from Colombia palm oil and used cooking oil (UCO) were developed considering the design of an existing hydrotreating unit. Due to restrictions design of the reactor (not including liquid quench), the model was configurated, including a recycle stream of the products from the separation of the low-pressure zone toward the reactor to obtain the required system conversion. After having the product with the required conversion, two process options are selected for new feed; the first one is sent to the stripper column area where the HVO and/or SAF are obtained, removing the maximum amount of water in the stream and the CO2 produced. A second option is to get HVO in the separation zone due to the low flow of non-condensable and products C5- to the stripping column. This means it operates outside the hydraulics limit without presenting a significant change in the final products.
A conversion reaction model evaluation of the system is performed with the design conditions of the plant. The yield of HVO and SAF in the first case was 82% and 6%, respectively, while in the second case, the conversion of HVO was 32% and SAF 53%. The high number of recycles in both cases is due to the management of exothermicity in the reaction zone and the restriction of the total conversion of triglycerides of the current. For this reason, to achieve the maximum conversion and to operate within the allowable temperature difference of the process in both cases, it was proposed to recirculate 10 times the feed for case I and 14 times for case II.