Hydrocracking process design

The MRH process is a hydrocracking process designed to upgrade heavy feedstocks containing large amount of metals and asphaltene, such as vacuum residua and bitumen, and to produce mainly middle distillates (Sue, 1989). The reactor is designed to maintain a mixed three-phase slurry of feedstock, fine powder catalyst and hydrogen, and to promote effective contact. 

The selectivity of the hydrocracking process is dependent upon the severity of operation. The experimental design was such that conversion was largely dependent upon temperature. It was not practical to achieve equivalent conversions by changing liquid hourly space velocity (LHSV). A typical selectivity change with temperature is illustrated in Table V. 

Coonradt, H.L. and Garwood, W.E. "Mechanism of hydrocracking." Industrial and Engineering Chemistry, Process Design and Development. 3(1) 38-45 1964. 

Source N. Y. Chen and W. E. Garwood, Selective Hydrocracking of n-Paraffins in Jet Fuels, Industrial and Engineering Chemistry Process Design and Development 19 315-318 (1978). With... 

To illustrate possible occurance of suboptimal solutions, let us consider an example of the hydrocracking process, which makes transportation products. The data were extracted from process simulation and it was assumed that the feed preheating and reaction sections are designed first followed by the fractionation section. 

At the heart of a refinery are its fluid catalytic cracker and hydrocracker, which break down heavy (long) hydrocarbon chains into lighter (shorter) ones. A catalytic reformer is used to create higher octane reformate, a more valuable naphtha distillate. Isomerization and alkylation are two chemical processes designed to boost the distillate s octane rating. Refineries send their products to end users or the petrochemical industry. 

Comparing the overall concentrations of these different carbons designated generally as structural patterns , measured before and after a process such as FCC or hydrocracking (see Chapter 10), enables the conversion to be monitored the simple knowledge of the percentage of condensed aromatic carbon of a feedstock gives an indication of its tendency to form coke. 

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