Boiling-point distribution cracking

The two residue feeds B and C have almost identical boiling point distribution, but the density and the Conradson carbon content value are somewhat higher for feed C than for feed B. This indicates that feed C should be a little bit more difficult to crack than the B feed and this was also notified when the two feeds were to be tested in the pilot unit. 

Figure 1. Boiling point distribution of products from catalytic cracking...

Figure 7.7 Boiling point distribution of liquid fuel formed over US-Y zeolite, a commercial cracking catalyst, a pillared clay (polymer-to-catalyst ratio 2 1) and comparison with a commercial gasoline sample...

Fignre 7.7 compares the boiling point distribution of liqnid products formed over US-Y, a commercial cracking catalyst and a pillared clay. In the same figure is plotted the boiling point distribution of a commercial gasoline sample. 

A second mechanism causing decreased oil yield is cracking, which is the thermal decomposition, probably by a free-radical mechanism, of long alkyl chains (14). It causes a downward shift in the boiling-point distribution and an increase in hydrocarbon... 

The most predominant application of the process gas chromatograph is to provide feedback for process control, in either open- or closed-loop control. In the case of a fractionation tower, one or more components are monitored, and the result then directly controls the operation of the tower. Griffen et al. (135) snmmarized the considerations involved in analyzer control of fractionators. More complex analyses are required for applications such as cracking products, polymerization reactor feed impurities, and high-purity product quality control. Systems for determination of boiling point distributions and octane ratings of refinery streams have also been developed. 

Tables V and VI show that the distribution of molecular types in the liquid products after cracking at 500° and 560°C shifts towards more aromatics, particulary monoaromatics, and polars with increasing boiling point range of the feed. The yields of monoaromatics increase at the higher temperature since they are favoured thermodynamically as dehydrogenation products of naphthenes. Polyaromatics are rejected to coke. The conversion of polars decreases with increasing boiling point of the feed at 500°C, but increases...

Under Cut/Blend sheet, the user can select a method to cut assay data into the pseudocomponent distribution. In this case, we choose Auto Cut , following the boiling point widths for cuts listed in Table 3.2. Since the VDU is operated under wet conditions, we will add makeup gas streams to represent cracked gases and add water and light components into the component list (Figure 3.10). We discuss the makeup of gas streams in Section 3.2.3. We choose the Peng-Robinson equation of state (EOS) for this model because of its thermodynamic consistency and better heat-balance calculation [1] (see Figure 3.11). 

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