Our problem is catalyst tapping blockage.
1- Tapping are for regenerated catalyst slide valve differential pressure ( high leg )
2-Stand pipe is sloped (about 25 degree)
3- Tapping located below stand pipe and there is cold : It shows catalyst don't flow there (Top of stand pipe is hot )
4-Purge air could not enter to tapping but amazing catalyst comes out from tapping. (It's like a check valve)
Have you had similar experience like our problem ?