NOVELTY - The apparatus has injecting ports for injecting a renewable fuel oil and a petroleum fraction into single risers. The injecting ports are retro-fitted to be corrosion resistant to the renewable fuel oil. The injecting ports are utilized for co-injecting a mixture of the petroleum fraction and the renewable fuel oil directly into the riser. The injecting ports comprise petroleum fraction injecting ports for injecting the petroleum fraction and independent ports for injecting the renewable fuel oil. The independent ports inject the renewable fuel oil directly into the riser.    USE - Fluidized catalytic cracking apparatus i.e. modified or retro-fitted fluidized catalytic cracker, for co-processing petroleum fraction and renewable fuel oil used in diesel and stationary turbines to convert cellulosic biomass e.g. wood, wood residue and agricultural residue, into fuel product. Uses include but are not limited to non-hydrodeoxygenated renewable fuel oil, non-deoxygenated renewable fuel oil, non-upgraded renewable fuel oil, thermally-processed cellulosic renewable fuel oil, rapid thermo-mechanically-processed renewable fuel oil, non-hydrotreated renewable fuel oil, non-upgraded renewable fuel oil, pyrolysis oil, pyrolytic liquid, thermo-pyrolysis oil and thermo-pyrolytic liquid to convert into diesel fuel, cellulosic-renewable index number qualifying-diesel fuel, petrol, cellulosic-renewable identification number qualifying-petrol, heating oil, cellulosic-renewable index number qualifying-heating oil, cellulosic fuel qualifying for cellulosic renewable identification number and D-code 7-compliant fuel.    ADVANTAGE - The apparatus utilizes a flash point of a renewable oil to be increased to reduce volatile content of a liquid system, so that cracking or conversion of vacuum gas oil is enhanced during fluid catalytic cracker operation, thus prolonging useful life of catalyst, and maintaining greater catalyst activity.    DESCRIPTION OF DRAWING(S) - The drawing shows a hydraulic circuit diagram of a fluid catalytic cracking unit.    Renewable oil feedstock (101)