What are the differences between using atmospheric residue and vacuum residue in a heavy oil catalytic cracking unit?
Thread Content
In domestic heavy oil catalytic cracking units, some use atmospheric residue as feedstock while others use vacuum residue. What effects would it have on the catalytic units if vacuum residue were replaced by atmospheric residue as the feedstock?
Theoretically, both reduced slag and normal slag can be used in catalysis; the key is whether it is cost-effective. In fact, the reduced residue from some crude oils can be used in catalytic processes, while the normal residue from some crude oils can also be used in such processes; however, the normal residue from some crude oils cannot be used in catalysis, let alone the reduced residue. Replacing the addition of normal slag with slag reduction mainly results in changes in residual carbon, viscosity, and heavy metal content; it is necessary to pay attention to changes in bed temperature, the physicochemical properties of the feed materials, and catalyst activity. Make adjustments in a timely manner. Some have better slag-reducing properties than ordinary slag, so it cannot be generalized.
Residuum fed into catalysis requires pre-hydrogenation; otherwise, a trade-off between yield and quality arises.
1. Different colors of the oil products 2. Different regeneration temperatures
Atmospheric residue is an excellent catalyst feedstock, but it is poor for residue reduction; it can only be blended in, and the amount used cannot be too large； It has high slag formation, high levels of asphaltenes and resins, high residue content, high levels of heavy metals, high sulfur content, and high viscosity. During blending, it results in large amounts of raw coke, low yields, easy contamination of the catalyst, an inability to increase the processing volume, and poor product quality ； When the reduced slag is replaced with regular slag, the plant’s yield increases, the processing capacity improves, the amount of raw coke produced decreases, and the bed temperature drops; adjustments need to be made promptly, which leads to a better distribution of the products and an improved product quality.
Apart from the issues mentioned above, it mainly depends on the device type and catalyst.
It’s already good enough to have oil for refining; even the M100 is processed via atmospheric distillation to obtain light oil. As for the catalyst feedstock, one can only imagine the situation, especially from August to October last year.
Regardless of the additives used, what matters most is the impact on parameters such as the density, residual carbon, salt content, metal content, and alkaline nitrogen of the resulting catalytic mixture. For the normal slag and reduced slag derived from the same raw material, the normal slag contains more wax oil components than the reduced slag. . . :lol
Regular slag is relatively better than reduced slag; reduced slag generally contains more resinous asphaltenes as well as more heavy metals, which pose a greater threat to catalysts, so it should be used in smaller amounts in blending