Bridgewall temperature & reformer tube outlet temperature

[ww2i]

We have an observation where bridgewall temperature is rising with reformer tube outlet temperature coming down.
Does it point towards catalyst deactivation?

[sys1]

Yes, it can point towards catalyst deactivation, but not by itself. In a fired steam methane reformer, the combination of increasing bridgewall temperature and decreasing reformer tube outlet temperature is a classic warning sign that warrants investigation, with catalyst deactivation being one of the leading possibilities.
The same trend can also result from several other issues:
Reduced heat transfer
Internal tube scaling
External deposits on tubes
Flame impingement or poor flame distribution
Burner problems
Uneven firing
Burner tip damage
Incorrect air-to-fuel ratio
Feed changes
Higher feed rate
Lower steam-to-carbon ratio
Increased methane concentration
Tube deterioration
Tube creep causing diameter growth
Changes in tube emissivity
Instrumentation issues
Drift in bridgewall thermocouples
Tube outlet thermocouple errors

Don't conclude catalyst deactivation immediately.

[tuan]

Rising bridgewall temperature together with falling reformer tube outlet temperature is consistent with catalyst deactivation, but it is not diagnostic on its own. The strongest confirmation comes from increased methane slip, higher fuel consumption, reduced reforming efficiency, and the exclusion of burner, feed, heat transfer, and instrumentation problems.