Pressure hydrocracking

Figure 24.1 is a sketch of a centrifugal pump, driven by a three-phase motor, with a turbine helper. This particular pump was charging a light gas oil stream to a high-pressure hydrocracker. The pump was operating quite close to its design conditions of... 

The flash of 27-multicomponent mixtures in the high pressure hydrocracking separator were calculated in this paper. To those polar components, special treatment were used. The properties M, Tc, Pc of petroleum fractions were calculated by Riazi and Daubeit [11](1980) correlations, and co was calculated by Lee and Keslefs correlation. A group of typical results... 

M.G. Hunter, D.A. Pappal and C.L. Pesek, Moderate pressure hydrocracking a profitable conversion alternative, NPRA annual meeting, paper AM 94-21. 

The early high pressure hydrocracking processes were very costly. For a hydrocracking process to be cost effective, lower pressures were necessary. 

More severe hydrotreating, such as mild hydrocracking at an H2 partial pressure of >6.9 MPa (1000 psig) and temperature of >400° C, can stiU further reduce sulfur content in the FCC feed. Mild hydrocracking of a 25° API VGO reduced the sulfur content of the FCC feed 98%, from 1.7 wt % to 0.03 wt % (40). This reduction can be expected to lower the SO content in the FCCU regenerator flue gas by about 90%. 

Basic to establishing whether power recovery is even feasible, let alone economical, are considerations of the flowing-fluid capacity available, the differential pressure available for the power recovery, and corrosive or erosive properties of the fluid stream. A further important consideration in feasibihty and economics is the probable physical location, with respect to each other, of fluid source, power-production point, and final fluid destination. In general, the tendency has been to locate the power-recoveiy driver and its driven unit where dictated by the driven-unit requirement and pipe the power-recoveiy fluid to and away from the driver. While early installations were in noncorrosive, nonerosive services such as rich-hydrocarbon absorption oil, the trend has been to put units into mildly severe seiwices such as amine plants, hot-carbonate units, and hydrocracker letdown. 

Pressure Vessels. Refineries have many pressure vessels, e.g., hydrocracker reactors, cokers, and catalytic cracking regenerators, that operate within the creep range, i.e., above 650°F. However, the phenomenon of creep does not become an important factor until temperatures are over 800°F. Below this temperature, the design stresses are usually based on the short-time, elevated temperature, tensile test. 

For refinery units such as hydrocrackers in which the hydrogen partial pressure is much higher, e.g., above l,350psi and the operating temperatures are above 800°F, the 2 A Cr-1 Mo steel is eommonly used. The higher alloy... 

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