100 Most asked questions by Chemical Engineers


download the ASKNORMLIEBERMAN APP http://h.fanapp.mobi/asknormlieberman1


Wednesday, October 7, 2015

Q&A - VACUUM TOWER

Vacuum Tower

Will:
In a vacuum tower, what parts of tower internals need to be designed for a large up-lift force, to prevent damage?

Norm:

Only the over-flash chimney tray, if the chimneys are designed for a 0.5 – 1.0 mm Hg DP.

3 comments:

  1. Dear mr. Norm.

    I am writing from SATORP, Jubail, KSA.

    In our atmospheric column, last 5 days, Naphtha and Kero became yellowish. Operators realised during routine samples, then we started to check in the whole kero and naphtha ciruit, resulting that all the loop are "contaminated". Material in overhead drum, pumps, exchangers, draw off kero tray, reboiler are same aspect. LAGO, side cut below Kero, colour is normal as ever. We increased around 1% amount of IR and PA in the whole column, but not major change observed, just a little bit lighter. Lab Analysis for Kero and Naphtha we can say are normal. Not change in IBP, FBP, sulfur content, and distillation. Special sample for asphalthenes for both and not detected. Sulfur content for Naphtha 0.0100 wt% and for Kero .0168 wt%. Iron .12 ppm-w in naphtha and 0.11 ppm-w for kero. Colour Saybolt for Naphtha +2 and +12 for Kero. Could you guide us about something else to do ij order to try to solve this trouble shooting? Best regards.

    ReplyDelete
    Replies

    1. The problem you described I have observed before at the Exxon Refinery. The problem is not due to crude unit operations, but contamination of the crude charge. There are two possibilities:
      1. Crude supply has been contaminated with olefin type materials.
      2. Cracked slops are being re-run on crude unit.

      To test my theory, get ½ bottle sample of kero and/or naphtha. Shake the bottle, and set it out in the sun. See if color then becomes more yellow, due to O2 reacting with di-olefins. It should take about 30 minutes for sample to become noticeably darker.
      There is a chemical treatment to suppress color degradation. I suggest you phone me at 1-504-887-7714 in U.S.A. The chemical treatment I have used before was very costly.

      Norm

      Delete

  2. The problem you described I have observed before at the Exxon Refinery. The problem is not due to crude unit operations, but contamination of the crude charge. There are two possibilities:
    1. Crude supply has been contaminated with olefin type materials.
    2. Cracked slops are being re-run on crude unit.

    To test my theory, get ½ bottle sample of kero and/or naphtha. Shake the bottle, and set it out in the sun. See if color then becomes more yellow, due to O2 reacting with di-olefins. It should take about 30 minutes for sample to become noticeably darker.
    There is a chemical treatment to suppress color degradation. I suggest you phone me at 1-504-887-7714 in U.S.A. The chemical treatment I have used before was very costly.

    Norm

    ReplyDelete