Water Filling or Water Sealing during start-up in Urea Plant.

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  • #111710
    Abdul
    Participant
      • Participant

      Water filling for reactor approx 180 minutes and water filling for VSCC and its overflow approx 60 minutes

      #111708
      irsan
      Participant
        • Participant

        Find enclosed my thoughts

        Thank you sir! I will learn more about the background function of each system. Hopefully, We can optimize the duration.

        #111706
        irsan
        Participant
          • Participant

          For all process the reactions are the same however process parameters are the different for each process. Some of the conventional process filled the reactor with ammonium carbamate or water then pressurized with high pressure pump and then feed ammonia & CO2 in Reactor.
          Following are the reason to take water before feed in
          1. 1st the heat of absorption produced when water is feed because the ammonia already present during Ammoniation, this heat act as activation of reaction.
          2. The Dehydration reaction (means the 2nd reaction) always takes place in liquid phase.
          3. Water feed in CO2 line it is sure that line is cleared because the CO2 line generally found choked.

          2022 Baboo Questions & Answers on Fertilizers Industries Volume 2

          Thank you very much, I downloaded QnA vol.1 about the water filling. Based on your explanation only specific spots (Reactor, VSCC and Overflow line) need to be filled.
          How about the duration? I plan to reduce the duration of this step because TEC plant consumes 4 hours

          As Mr.pbaboo mentioned, with the snam process, we have this experience: At the reactor, there are temperature probes, including one temperature probe for reaction performance at the bottom of the reactor. After ammoniation, we control the amount of water filled based on the flow rate (through monitoring the water tank level) combined with calculating the volume of the required submergence equipment, together with the exothermic reaction when filling water, the temperature at the bottom of the tower will gradually increase. When the temperature starts to level off and stay constant, it is time to stop filling water into the synthesis tower.

          Thank you for your response, very insightful. We only inject water based on time as a best practice.

          #111677
          zavtranguyen
          Participant
            • Participant

            For all process the reactions are the same however process parameters are the different for each process. Some of the conventional process filled the reactor with ammonium carbamate or water then pressurized with high pressure pump and then feed ammonia & CO2 in Reactor.
            Following are the reason to take water before feed in
            1. 1st the heat of absorption produced when water is feed because the ammonia already present during Ammoniation, this heat act as activation of reaction.
            2. The Dehydration reaction (means the 2nd reaction) always takes place in liquid phase.
            3. Water feed in CO2 line it is sure that line is cleared because the CO2 line generally found choked.

            2022 Baboo Questions & Answers on Fertilizers Industries Volume 2

            Thank you very much, I downloaded QnA vol.1 about the water filling. Based on your explanation only specific spots (Reactor, VSCC and Overflow line) need to be filled.
            How about the duration? I plan to reduce the duration of this step because TEC plant consumes 4 hours

            As Mr.pbaboo mentioned, with the snam process, we have this experience: At the reactor, there are temperature probes, including one temperature probe for reaction performance at the bottom of the reactor. After ammoniation, we control the amount of water filled based on the flow rate (through monitoring the water tank level) combined with calculating the volume of the required submergence equipment, together with the exothermic reaction when filling water, the temperature at the bottom of the tower will gradually increase. When the temperature starts to level off and stay constant, it is time to stop filling water into the synthesis tower.

            #111676
            zavtranguyen
            Participant
              • Participant

              3. Water feed in CO2 line it is sure that line is cleared because the CO2 line generally found choked.

              Hi all,
              Yes, ” Water feed in CO2 line it is sure that line is cleared because the CO2 line generally found choked” This is very important, if you have not ensured that the CO2 gas line is clear (without any blockages), it is best to flush it at the positions before and after the valves just before the feeding time (as close to the feeding time as possible). By doing this, when you switch the CO2 stream into the reactor, it will be truly safe. On the other hand, if the CO2 stream is transferred from the vent to the reactor, if the flow is lost and the pressure out of the CO2 compressor does not decrease and balance with the reactor bottom pressure, meaning that the CO2 line is blocked, if the troubleshooting is not skillful, you will trip the CO2 compressor due to a surge.
              Regards,

              #111668
              Mark Brouwer
              Keymaster
                • Expert

                Find enclosed my thoughts

                #111653
                irsan
                Participant
                  • Participant

                  Please confirm the enclosed scheme is what you mean.

                  I confirmed as the file attached, only the bottom stripper needs to be revised.

                  #111643
                  Mark Brouwer
                  Keymaster
                    • Expert

                    Please confirm the enclosed scheme is what you mean.

                    #111634
                    irsan
                    Participant
                      • Participant

                      For all process the reactions are the same however process parameters are the different for each process. Some of the conventional process filled the reactor with ammonium carbamate or water then pressurized with high pressure pump and then feed ammonia & CO2 in Reactor.
                      Following are the reason to take water before feed in
                      1. 1st the heat of absorption produced when water is feed because the ammonia already present during Ammoniation, this heat act as activation of reaction.
                      2. The Dehydration reaction (means the 2nd reaction) always takes place in liquid phase.
                      3. Water feed in CO2 line it is sure that line is cleared because the CO2 line generally found choked.

                      2022 Baboo Questions & Answers on Fertilizers Industries Volume 2

                      Thank you very much, I downloaded QnA vol.1 about the water filling. Based on your explanation only specific spots (Reactor, VSCC and Overflow line) need to be filled.
                      How about the duration? I plan to reduce the duration of this step because TEC plant consumes 4 hours

                      #111632
                      irsan
                      Participant
                        • Participant

                        Dear Mark, the scheme for water filling is attached, I am looking forward for your suggestion

                        #111604
                        pbaboo
                        Participant
                          • Expert

                          For all process the reactions are the same however process parameters are the different for each process. Some of the conventional process filled the reactor with ammonium carbamate or water then pressurized with high pressure pump and then feed ammonia & CO2 in Reactor.
                          Following are the reason to take water before feed in
                          1. 1st the heat of absorption produced when water is feed because the ammonia already present during Ammoniation, this heat act as activation of reaction.
                          2. The Dehydration reaction (means the 2nd reaction) always takes place in liquid phase.
                          3. Water feed in CO2 line it is sure that line is cleared because the CO2 line generally found choked.

                          2022 Baboo Questions & Answers on Fertilizers Industries Volume 2

                          #111594
                          Mark Brouwer
                          Keymaster
                            • Expert

                            Thank you for your email. Can you provide a sketch to where in the TEC ACES21 synthesis you supply condensate during start-up ?

                            Also refer to: https://ureaknowhow.com/tec-aces21_flowscheme/

                            #111581
                            irsan
                            Participant
                              • Participant

                              Dear Sir,
                              We have several Urea Plants with various licensors: Stamicarbon, Saipem, and Toyo Aces 21. During start-up, we do a step of water sealing or water filling. In our experience, for Stamicarbon Plant only need approximately 20-30 minutes to complete this step, because the line that should be sealed/filled only the Reactor overflow to Stripper.
                              The injection point of Saipem plant is different, only the bottom reactor and HPCC should be sealed/filled with condensate during start-up. The time needed is 15 minutes for each reactor with a total of 30 minutes.

                              The newest plant is Toyo Aces 21 with totally different injection points and long duration, in manual procedure the time needed is 240 minutes in total. Steam condensate is injected to synthesis by two pumps HP flush and LP Flush.

                              My question is, what are the purposes of this water sealing or water filling? I think the stamicarbon plant seal for preventing CO2 wrong direction. Saipem bottom reactor is filled with condensate as a part of reaction to form urea to control the N/C ratio. But I have no idea of Toyo Plant, What it is for? I wish to shorten the duration of water filling for improvement in Toyo Plant.
                              Your suggestion is very appreciated. Thank you

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