H2SO4 injection in urea melt

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Viewing 15 posts - 16 through 30 (of 34 total)
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  • #95521
    serpoush1
    Participant
      • Participant

      dear Le!
      OK. solution temp increase about 2.7 – 3 degree Celsius increase biuret.
      ans: What is ratio(mole H2SO4/mole urea) in your test?and how much metric ton urea prilled (at test time)?
      thanks

      #95519
      Ban
      Participant
        • Expert

        Dear vedantam!
        We have not dedusting system in the prilling top.
        Best regards!

        #95514
        vedantam
        Participant
          • Participant

          Dear Inban,

          You were doing a good experiment. Do you have dedusting arrangement in the prill tower top?

          What is the height of the tower and flow of air through the tower.

          Based on the above, we may think of using water or H2SO4 as scrubbing media. Ammonium Sulphate can also be produced as a byproduct.

          Rergards,

          Srinivas

          #95511
          Ban
          Participant
            • Expert

            Dear ahsansarfraz!
            Actully, ammonia level at prilling tower depend on location where you take sample analysis, in our case, the highest point is 94 mg/m3 and the lowest point is below 60 mg/m3. My target is to reduces level of ammonia to below 60 mg/m3. By the way, do you think the prill hardness can improve after H2SO4 injection?.

            #95508
            M Ahsan Sarfraz
            Participant
              • Expert

              Dear Inban!
              Really interesting experiment but may i knw what is the present level of ammonia emission at your prilling tower which you are trying to control. Beside this what was the impact on Ammonia emission of tower during the time you have dozed the acid (did you measured the impact??).
              What is the emission level you are aiming upon as usually TEC adn STEMC prill tower operates around 25 mg/NM3/hr we are operating at 14mg. so would like to know your present level and target.

              #95507
              basheer
              Participant
                • Participant

                Hi Gentelmen

                it is interesting subject. Injection of H2SO4 or AS is going to improve the mechanical strength of urea prills and also reduce the ammonia emission. However, one should be worry about the corrosion that may occur in the prilling tower structure. Also the color of the final product may appear to be yellowish which may be not accerpted by farmers.

                Best regards

                #95506
                Ban
                Participant
                  • Expert
                  quote david_herrero:

                  To Inban: Did you run the trial during enough time to measure the ammonia emission?. If so, what were the values you got?.

                  David Herrero.

                  Thank for your reply
                  Hereafter is my trial, the test lasted 7 hours, from 9 am to 4 pm

                  Flowrate of injection is 0.11 m3/h (design), but when i did this test, i increased in 3 steps: 0.04 m3/h; 0.08 m3/h; 0.11 m3/h.

                  Steps: 0.04 0.08 0.11 0.00 m3/h
                  current 117 115 113 119 A
                  dis press 13.4 13 12.8 14.5
                  biuret 0.97 1.07 1.09 0.95
                  Nh3: 78.22 49.48 89.25 94.66 mg/m3

                  Plant load did not change!

                  #95503
                  david-herrero
                  Participant
                    • Participant

                    Dear all, you can find several patents on the web regarding sulphuric acid injection into urea melt. They claim ammonia emission from the prilling tower could drop to 5 mg/Nm3 without further air treatment. Biuret content will go sligthly higher and the final content of AS would be around 0,5%. Water content would not be affected if 98% sulphuric acid is used. The point of injection is at the pump suction line to assure correct mixing and reaciton with the free ammonia. If enough gases are present due to the reaction, cavitation, of course, will appear.

                    The AS content makes this urea is only valid for agriculture (not industrial grade). As far as I know there was limited real experience (I guess this would have been an extended practice if it have had plenty of success)

                    To Inban: Did you run the trial during enough time to measure the ammonia emission?. If so, what were the values you got?.

                    BR,

                    David Herrero.

                    #95502
                    Mark Brouwer
                    Keymaster
                      • Expert

                      Please study carefully the patents indicated by Saima Abdul Rasheed.
                      These patents mention exothermic reactions and even explosion risks.
                      As byproducts CO2, NH3 and toxic components like ammonium sulphamate and sulphamic acid are mentioned.
                      Be careful thus !

                      When ammonia concentration reduce due to reactions with sulphuric acid, the biuret formation reaction: 2 urea <=> biuret + NH3 goes to the right side. This leads to more biuret.

                      More gasses cause cavitation of the pump.

                      #95499
                      Ban
                      Participant
                        • Expert

                        Dear all,
                        Thank you for all reply
                        Do you have any document about H2SO4 injection into urea melt?, what kind of side reaction happens in this solution?, how to explain the biuret content increasing?, and why urea melt solution cavitate?

                        #95498
                        Mark Brouwer
                        Keymaster
                          • Expert

                          Yes and
                          Urea can also decompose into the gasses NH3 and cyanaric acid (HNCO): this reaction might also be promoted when H2SO4 reacts with NH3.
                          Plus when the temperature increases also more vapours form.

                          #95497
                          saimaabdulrasheed
                          Participant
                            • Participant

                            The vapours formed are of water and the acid.

                            #95496
                            naeem-engr
                            Participant
                              • Participant

                              i think the proper way is to inject any kind of fluid whether that is UF-85 or H2SO4 at the suction of Urea melt pump to have a better mixing of the both fluids…

                              #95495
                              m-farooq
                              Participant
                                • Expert

                                dear Le inbam

                                i would like to suggest you to inject H2SO4 at discharge line of molten urea pump near prilling basket by using a acid dozing pump .
                                Do you have any washing/scrubbing system at top of your prill tower
                                Regards

                                #95494
                                Ban
                                Participant
                                  • Expert

                                  Dear all,
                                  I am sorry for late reply.
                                  @m.farood:

                                  The purpose of this injection is to reduce ammonia content in the prilling top as per environment requirement



                                  @mark
                                  .brouwer:
                                  – Flowrate of injection is 0.11 m3/h (design), but when i did this test, i increased in 3 steps: 0.04 m3/h; 0.08 m3/h; 0.11 m3/h.
                                  – yes, i want to reduce ammonia emission from prill top
                                  – yes, solution temp increase about 2.7 – 3 degree celsius resulting biuret increase!
                                  When i increase acid flowrate, the current of melt pump decreases so i think density of solution decreases, you said that gasformation occurs but what is the gas?
                                  When i stop putting acid injection the curent and dis press of melt pump go higher
                                  Steps: 0.04 0.08 0.11 0.00 m3/h
                                  current 117 115 113 119 A
                                  dis press 13.4 13 12.8 14.5
                                  biuret 0.97 1.07 1.09 0.95

                                  Plant load not change
                                  thanks

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