Urea Reactor: High Efficiency Trays

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  • #95229
    Ashraf Khan
    Participant
      • Participant

      We had 10 trays in original design of the urea reactor. 05 more trays were recently installed and result was increase in conversion efficiency. Although, it is difficult to exactly measure the quantum of increase.
      We have surplus low pressure steam (generated in carbamate condensers) but are short of medium pressure steam (used in stripper); high pressure steam is letdown to fulfill medium pressure requirement. Therefore, we plan to further increase the reactor conversion efficiency to decrease stripper steam consumption (stripper bottom temperature being a limitation, lower steam consumption in stripper shall also result in reduced steam generation in carbamate condensers).

      Mark! What does StamiCarbon do to increase the feedstock mixing in reactor bottom? I am asking this question because most of the Stami plants have opted for LSE only. This may be because of having some device in the reactor bottom like VM.

      Dear All! Please speak about VM & LSE.

      #95228
      engahmed84
      Participant
        • Expert

        can we say that the plug flow is the key for high conversion or the tray design or we can consider that the PF in combination with high eff. trays is the key for better conversion ??

        also can we say that introducing the liq and gas from bottom and thus transfer against gravity which will provide suff. residence time inside reactor or the large volume of reactor is the one that provides the suff. residence time ??

        #95226
        muhammad-adnan-hanif
        Participant
          • Expert

          Assalamo Alaikum Ashraf,

          How are you dear ?.

          I agree with mark wrt increase in conversion by installing higher efficiency trays or other mixer / reactor internals.

          Installing of internals may increase pressure drop which means more energy requirement to push the rotatory equipments like CO2 compressors and HP Ammonia pumps to maintain same flow rates. Therefore, a detail review is always needed for such type of modifications. As per my knowledge, the estimated pressure drop of such type of internals is ~ 2 kg/cm2.

          Therefore, in my opinion, it is always a compromise between plant higher through put and energy efficient / conservation especially in regions where energy cost is not significantly higher.

          quote ask:

          Dear All,

          A Russian Company offers following 02 devices (installed at urea reactor bottom) to increase urea reactor’s conversion efficiency and thus to save steam in urea stripper. A brief description is given here:

          Vortex Mixer (VM) helps in forming a homogenized feedstock mixture in the Reactor bottom to increase contact surface of NH3 & CO2; necessary for higher conversion rate. As per vendor’s claim, contact surface is increased by 1.5 – 2.0 times compared to conventional mixing arrangements.

          Longitudinal Sectioning Element (LSE) ensures complete bonding of NH3 & CO2 into Carbamate and prevents back mixing of Carbamate in the Reactor bottom.

          These devices, especially LSE, have been mostly installed in STAMI plants (~10).

          I shall highly appreciate your knowledge sharing regarding above devices and also about other means (excluding ammonia and CO2 pre-heating), used to increase urea reactors’ conversion efficiency and saving steam in urea stripper.

          ASK

          #95223
          Mark Brouwer
          Keymaster
            • Expert

            I think it is fair to say that reactors with High Efficiency Trays show a better conversion that reactors without trays.
            Each Licensor has its own design of High Efficiency Trays. Which design is better is in my opinion more difficult to prove as measuring accurately the reactor conversion is not so easy.

            What is your experience ?

            #93686
            Ashraf Khan
            Participant
              • Participant

              Dear All,

              A Russian Company offers following 02 devices (installed at urea reactor bottom) to increase urea reactor’s conversion efficiency and thus to save steam in urea stripper. A brief description is given here:

              Vortex Mixer (VM) helps in forming a homogenized feedstock mixture in the Reactor bottom to increase contact surface of NH3 & CO2; necessary for higher conversion rate. As per vendor’s claim, contact surface is increased by 1.5 – 2.0 times compared to conventional mixing arrangements.

              Longitudinal Sectioning Element (LSE) ensures complete bonding of NH3 & CO2 into Carbamate and prevents back mixing of Carbamate in the Reactor bottom.

              These devices, especially LSE, have been mostly installed in STAMI plants (~10).

              I shall highly appreciate your knowledge sharing regarding above devices and also about other means (excluding ammonia and CO2 pre-heating), used to increase urea reactors’ conversion efficiency and saving steam in urea stripper.

              ASK

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