• Why should water boot be vertical? We want to implement water wash of overhead condenser, but 3 phase separator is bottleneck, esspecially water boot. We can not extend it verticaly, to get more residence time for water (space limitations). Potential option is to extend boot horizontaly - to increase its DIA to bi as wide as vessels, or to change boot with another smaller vessel, to provide residence time. Are this options even applicable or must hold on to already proven solution, like vertical boot?



  • S M Kumar, Energy Environment Engineers, s.m.kumar@outlook.com

    Interesting question. A sketch would have helped. Why not a horizontal vessel below, piggy back style. Diameter/length to provide adequate residence time + gaps between levels.



  • Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br

    Three phase separation vessels can be vertical or horizontal, vertical vessels are mainly applied when there is a large amount of vapor to be separated from a small amount of the liquid fluid. According to the literature (the classic article from W.Y. SVRCEK & W.D. MONNERY, 1994 is a good reference) describes that the boot is applied to three phase separation vessels when the heavy liquid (in this case, the water phase) amount is lower than 15 to 20 % in weight and a weir is applied when the heavy liquid volume is high.

    Raising the boot diameter can be a good strategy to improve the residence time and reach a better separation between the heavy and light liquid, but the boot diameter should not be higher than 50 % of the vessel diameter aiming to ensure adequate liquid hold up time. The minimum boot diameter can be found in the literature and the length of the boot should not be less than 900 mm to provide adequate hold up time to the heavy phase and residence time to separation. As previously mentioned, the specialized literature presents guidelines capable of helping to solve this question in a good way.

    Once the modification will be conducted, maybe it is a good moment to verify the whole design of the separation vessel aiming to debottleneck this system. Another suggestion is related to the washing water injection system which will be installed, it's important to take care with this system especially considering the adequate dispersion device (sprinkler nozzle or static mixer) aiming to ensure adequate dispersion of the water and avoid corrosion-erosion phenomena in the pipe or heat exchanger which can lead to contention loss and process safety accidents.