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  1. JohnCalvin

    Help: NOx determination upstream of Cold Boxes

    I am urgently looking for any advice on what the accepted methods for determining NOx's are in ethylene and propylene entering cryogenic units. I am sure that anyone who owns such units is aware of the explosive hazard cause by NOx gums and NOx salts. I have two questions: What operation...
  2. JohnCalvin

    Salt build up in Benfield Units (acceptable levels?)

    Hello, Can anyone who has experience in Benfield units please tell me what sort of levels of potassium salts (aka PBS)are acceptable in the solution of the Hot Potash process? What are the typical levels experienced in these units and do they adversely affect your operations? If so, at what...
  3. JohnCalvin

    Silicate clays: Dispersion methods

    We have a big fouling problem on one of our acid gas strippers. It works on an ammonium carbonate system to remove CO2 and H2S. The make-up water for the tower however has a high silica content and now we sit with a cemented stack of rings which we cannot unpack. The stuff is high in Si, Fe...
  4. JohnCalvin

    Why do hydrocarbons cause foaming?

    To 25362, Thank you for the lengthy debate - I think I have a better understanding now. Regards, John Calvin
  5. JohnCalvin

    Why do hydrocarbons cause foaming?

    To 25362, thank you once again for your correspondence and experience. Foaming is definitely a complex field with many variables.I just want to ask one more question concerning this last response of yours and that is are the examples which you cite all in the context of amine units? I just want...
  6. JohnCalvin

    Why do hydrocarbons cause foaming?

    To 25362 I see an area which we may be approaching from different sides. I agree fully that due to the very nature of a gas passing through a liquid that foaming will always be present. However, analytically, i.e. in laboratory tests, a foam has been defined as having a certain height (> 10 cm...
  7. JohnCalvin

    Why do hydrocarbons cause foaming?

    Thank you for the informative reply. If I have understood you correctly then hydrocarbons are not the cause of foaming per se, but they do have the propensity to stabilise it. Is this correct? The primary cause in chemically induced foam would be the surfactant like chemicals. Am I right? I...
  8. JohnCalvin

    Why do hydrocarbons cause foaming?

    All, I wish to take issue with someone about the popular theory that hydrocarbons cause foaming and to find out why. I have read quite a bit on the subject esp. in Ullman's Encyclopaedia of Industrial Chemistry. I have come to the conclusion that there are two general kinds of foam causes, viz...
  9. JohnCalvin

    Critical density and viscosity in Benfield type processes

    Are there critical values for density and viscosity for which it may become difficult for a Benfield or related process to operate, if it is exceeded? If so, where can I obtain an index for such values? Regards, JohnCalvin@Geneva
  10. JohnCalvin

    Antifoam dosage in Benfield Process

    Hello, Thank you all for your answers - allow me to reply a little while. The original licensors of Benfield were Linde and they actually designed the process without antifoam usage. Be that as it may, UOP bought the process from them and when foaming was encountered, they recommended a...
  11. JohnCalvin

    Antifoam dosage in Benfield Process

    We have a Benfield process to remove CO2 from an LPG stream before it goes to a cryo unit. Currently we experience foaming problems and the dosage of antifoams is necessary. My question is two-fold: 1) is there an upper concentration limit above which it becomes simply ridiculous to dose any...

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