Commercial reactor yields, naphtha

Table IV. Prediction of Commercial Reactor Yields—Naphtha Pyrolysis...

KINPTR simulations of commercial reforming (Table XVIII) will be used in this section to demonstrate process sensitivity. In the base case, a full-range Mid-Continent naphtha (55 wt. % paraffins) is reformed to a constant octane of 90 R + 0 over the entire cycle. With a reactor pressure of 1695 kPa and a 7.2 H2 recycle ratio, the start-of-cycle reactor inlet temperature to achieve target octane is predicted to be 759 K. The deactivation simulation shows that it would take about 1 year to reach the end-of-cycle temperature of about 798 K. The start-of-cycle C5+ yield for this case is 86 vol %. The model predicts that the yield would decline by 4.8 vol % over the cycle. 

The DCC has two reactor operating modes DCC-I (Riser-plus fluidized dense-bed reactor, maximum propylene mode) and DCC-II (Riser reactor, maximum iso-olefins mode). The DCC can process different heavy feeds— VGO, DAO, coker gasoil, atmospheric residue, VR, etc. Paraffinic feedstocks are the best feeds for DCC. In DCC maximum propylene operation mode, over 20 wt% propylene yield can be obtained from paraffinic feedstocks. The naphtha and middle distillates streams from the DCC unit can be used as blending components for high-octane, commercial gasoline and fuel oil, respectively. 

The experimental work was conducted in the profile controlled pyrolysis pilot reactor, PCP. This unit was developed in 1967 and its performance has closely reproduced the pyrolysis yields obtained in commercial-size coils using naphthas and gas oils as feedstocks. 

This present paper presents the kinetic-mathematical model developed to describe the overall decomposition rate and yields of the naphtha feedstock cracking process. The novelty and practical advantage of the method developed lies in the fact that the kinetic constants and yield curves were determined from experiments carried out in pilot-plant scale tubular reactors operated under non-isothermal, non-isobaric conditions and the reactor results could readily be applied to simulate commercial scale cracking processes as well. During the cracking experiments, samples were withdrawn from several sample points located along the reactor. Temperature, as well as pressure were also monitored at these points[2,3]. 

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