Onstream Catalyst Replacement Reactor

In OCR configuration (Chevron process technology), the guard reactor is an ebullated bed reactor. The feed is introduced at the bottom of the reactor and flows upward through the catalyst, slightly (<3%) expanding the catalyst bed. Fresh catalyst is added at the top of the bed and spent catalyst is withdrawn at the bottom. Both catalyst addition and withdrawal are batch operations, usually done once a week, and this creates a plug flow of catalyst. Thus, the least active catalyst is in contact with most reactive feed at the bottom of the reactor. The upward flow of feed in reactor results in liquid as the continuous phase. Hydrogen is needed only for reaction and not for ebullating the bed. Pressure drop in the bed is low and constant. The catalyst used is spherical with high HDM activity, which allows for downstream fixed-bed reactors to operate at lower temperature.

A charge heater controls the feed temperature. The temperature inside the reactor is controlled by liquid quenching through a quench distributor located at different elevations in the reactor.

The advantages of a permutable or OCR reactor system for guard reactor are

1. Greater run length.

2. Higher space velocities or increased unit throughput.

3. Higher conversion of resid.

4. Increased stream factor.

+1 0

Post a comment