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Home Forums Coking Technical Fractionation & Process Process FORMATION OF POLYMER IN THE LCGO STREAM

This topic contains 2 replies, has 3 voices, and was last updated by  Alan R. English 7 years ago.

  • Author
  • #20100


    Hello Dear colleagues,

    I currently have a problem with the formation of a polymer in the LCGO, this is found frequently in the cleanning of the pumps of extration and occasionally in the Tower of oil wash sponge, would like to know if any of you has happened this problem and how you have solved it, If you have useful information for this evaluation that you can provide.

    Before hand thank you very much for your cooperation,

    Jesus Emilio Morillo.
    Process engineer
    Delayed coker unit

  • #20101

    Evan Hyde

    Hello Jesus

    I have a few questions to clarify your question….

    1. you are talking about the sponge tower bottoms pump, yes?
    2. Do you have any data of the composition of the polymer? There are many types of polymers to additional information would be helpful.
    3. Do you have any photos of the material? Is is sticky or solid?
    4. Where exactly is the poylmer found? Seal face, pump case, pipe around the pump
    5. What temperature is the pump running at?

    Many polymers in cokers are formed by di-olefins overheating and polymerizing. Reactions are a function of time and temperature. Eliminate high residence time dead zones or decrease the temperature.

  • #20113

    Diolefins and high potential gum values are often seen in FCC gasoline product when riser outlet temperatures (ROT) exceed 1000 F (538 C). They are less commonly observed in the LCO but this is likely only because potential gum is not an LCO product specification.

    Polymer-like formations are often observed in the stripper, debutanizer or LPG tower reboilers when HCO or slurry is used as the heating medium. As Evan suggested, in this case the high tube wall temperatures which result from using hotter-heavier reboiling medium dramatically increase the rate of diolefin polymerization.

    Based on these observations, I believe you have a few courses of action. Reducing ROT or increasing MAT activity or catalyst-to-oil ratio will shift the balance of reactions away from thermal cracking and toward catalytic cracking. I am surprised that you are seeing polymer in the sponge column since this column typically operates at low temperature (less than 100 F (38 C)). Is the oil heated elsewhere where the polymer could form and then be carried into the column after cooling?

    Another possible, but rare, mechanism could occur if you are drastically overdosing liquid metals passivators such as antimony. If your metals passivator deposition efficiency is less than 70% you may be in an overdosing situation. Testing for metals in the deposits is also recommended.

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