Transient Reactor Behavior during Start-Up

Modeling of Processes and Reactors for Upgrading of Heavy Petroleum 

The results illustrate how the hydrocarbon front moves slowly down through the catalyst bed, gradually filling the reactor vessels. After 100 min, a small amount of product can be spotted at the outlet this moment corresponds to the mean residence time, which is defined by the interstitial liquid velocity. The system finally achieves stable behavior at 200min. It can be noticed that in steady-state regime, the predictions are in good agreement with the experimental observations. 

The first relevant parameter is establishing when quenching must be initiated in order to achieve thermal stability. The model was set up to examine the following possible 

The major conclusion of this part of the analysis is that quenching must start before or as soon as the hydrocarbon reaches the quench zone. Even a small delay in quench start-up may lead to rapid overheating, which has a great impact on the operation of the unit. 

FIGURE 8.27 Transient temperature profiles under stabilized catalyst conditions, (a) Ql, Q2, Q3 start simultaneously at 60min (b) Ql, Q2, Q3 start sequentially at 10,20, and 40min, respectively (c) Ql, Q2, Q3 start simultaneously at lOmin. 

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