Gravity hydrocracking

An ft catalyst was prepared containing 3.1 wt % Pd, and used to hydrocrack a refractory gas oil (25.0° API gravity molar weight 216 53 vol % FIA aromatics) that had been hydrotreated to 4.2 ppm N, and fortified with dimethyl disulfide to a total sulfur content of 1130 ppm. 

Question How does this affect the amp load on the motor driver Well, the feet of head has gone down by about 10 percent, and the specific gravity has gone up by about 10 percent. Therefore, the horsepower or work per barrel of liquid pumped, remains constant. But the number of barrels has increased by 6000 bbl/day, or 35 percent. Then, the amp load on the motor driver would also increase by 35 percent. If I had not remembered this, prior to cooling the hydrocracker feed, the motor would have tripped off. As it was, I had the steam to the turbine increased. So as to decrease the motor amps to 60 percent of maximum, before cooling the gas oil. Omission of this detail, would have had embarrassing and possibly negative contractual consequences. 

Besides influencing over-all reaction rates, pore diffusion can cause changes in selectivity. An extreme example of this was observed (26) when a high molecular weight California solvent-deasphalted oil was hydrocracked over a small pore size palladium zeolite catalyst at high temperatures. The feedstock gravity was 16.4° API, and 70% boiled above 966°F. The resulting product distribution is compared with that... 

Figure 5. Reactor temperature and specific gravity of the recycle feed as a function of time-on-stream for recycle-to-extinction and single-pass modes of hydrocracking using NiW/RE-X catalyst. (Reproduced from reference 45, Copyright 1983 American Chemical Society.)...

Chlorine Content Regulation. The level of chlorine on the catalyst is quite important for a proper catalytic performance. If it is too low, the most important reactions such as dehydrocyclization and isomerization have a very low rate. If it is too high, the catalyst has high activity for hydrocracking. An excessive chlorine content in the catalyst is evidenced by a loss in hydrogen yield, an increase in the recycle gas gravity, a loss of C5-I- yield, low temperature drop in the last reactor, or even an increase in the temperature. 

In order to obtain more information about the use of H-Al mixed oxides as catalyst supports, we have studied the catalytic properties of two NiW catalysts, one suppmted on alumina and the other supported on 15 H-Al mixed oxide. The activity test were carried out in the presence of a hydrotreated cracked feedstock under typical mild hydrocracking eniting conditions ( T= 380 C, PH2= 800 psig, LHSV= 0.55 h l, H2/HC ratio= 1000 Nm An. The feedstock had the following properties sulfur 0.394 wt%, nitrogen= 460 ppm, aromatic content= 48 wt%, A.P.I gravity = 26.0, 370 C" " firaction= 42 v%. The catalysts contained 20 wt % WO3 and 6 wt% NiO, respectively, and they were prepared using the pore volume technique. 

The liquid phase continuity equations for the components and GOi contain the rate equations expressed by Kumar and Froment [2007] in terms of the single-event approach, already presented in Section 2.4.4 Hydrocracking of Chapter 2. Their most advanced version of the simulation model characterizes the VGO-feed by 1266 components and GOi. The current methods used for the analysis of heavy petroleum fractions do not permit to reach such detail, but methods have been developed that reconstruct their composition at the molecular level starting from global analytical results such as carbon-, hydrogen-, and sulphur-content, specific gravity, mass spectrometry, distillation curve... [Hudebine and Verstraete, 2004 Martinis and Froment, 2009 Charon-Revellin et al, 2010]. 

Distillation data and specific gravity are the most common properties used as inputs into empirical correlations to characterize petroleum fractions. This characterization is achieved by means of correlations that are useful for determining molecular weight, critical properties, etc. They can also be utilized for distinguishing reaction products as pseudocomponents or lumps (naphtha, middle distillates, etc.) of some typical refinery processes such as hydrocracking, catalytic cracking, etc. (Ancheyta et al., 2005b). To have accurate and reliable representations of distillation data for further interpolation, a strict analysis of other approaches apart from the traditional interpolation techniques is mandatory. 

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