Reaction mechanism of residue hydrocracking
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In fluidized-bed residue hydrocracking, the temperature ratio of the second reactor to the first is higher, and coking is reduced simultaneously. How can this be explained?
Pay attention to the feed rate for the two reactors connected in series, as their space velocities are different. Although the temperature in Section 2 is high, the large feed rate and high space velocity make coking unlikely. To determine coking, one needs to consider both temperature and space velocity. No temperature increase at low speeds, and no reduction in feed at high temperatures.
The oil of the second type is lighter than that of the first type; this explanation should be reasonable.
Personal opinion: 1. The first reaction stage has a lower temperature than the second; the aromatic saturation reaction is constrained by thermodynamic equilibrium, and the first stage is favorable for the progress of this aromatic saturation reaction. 2. The secondary feed is already hydrogenated oil. 3. A higher secondary reaction temperature is more conducive to deep cracking and hydrogenation. In summary, the theme becomes easy to understand.