![]() These processes normally operate with low conversion rates with temperatures higher than 400 oC and pressures above 150 bar. The main difference between the available technologies is the reactor characteristics. ![]() ![]() ![]() These units aim to improve the residues quality either by reducing the contaminant content (mainly metals) like an upstream step to other processes, as Residue Fluid Catalytic Cracking (RFCC) or to produce derivates like fuel oil with low sulfur content. However, face of the crescent demand for high-quality derivates, the investment can be economically attractive. These units are employed when the feed stream has high contaminant content (mainly nitrogen) and the refinery looks for the total conversion (to produce middle distillates), this configuration is presented in Figure 4. The main disadvantage of this configuration is the reduction of the hydrocracking catalyst activity caused by the high concentration of ammonia in the reactor, but this configuration requires lower capital investment. The organic nitrogen has permanent effect blocking the catalytic sites and leading to coke deposits on the catalyst. In some cases, the increase of ammonia concentration in the catalytic bed is used like an operational variable to control the hydrocracking catalyst activity.
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