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production aqua ammonia
- Thread starter m.edwer
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- #3
i need to design unit production aqua ammonia 25% with a capacity 1200 t/day so it is requested from me to design this unit
so i need any information about the mixing nozzel use or any supplier for unit any information helped me in design of this unit
so i need any information about the mixing nozzel use or any supplier for unit any information helped me in design of this unit
Take a look at this website -
Good luck,
Latexman
To a ChE, the glass is always full - 1/2 air and 1/2 water.
Good luck,
Latexman
To a ChE, the glass is always full - 1/2 air and 1/2 water.
georgeverghese
Chemical
A few precautions / hints that you may find useful:
a)Heat of solution for ammonia is negative (i.e there is a chilling effect upon mixing, starting with pure ammonia in the liquid phase)
b) Choose an operating pressure for the mixing operation that will maintain the aqueous am. at above 0degC (say 10degC), so that water doesnt freeze
c) There is of course the auto - refrigeration effect when pure ammonia at high pressure is let down to the pressure of the mixing operation.
c)Refer to charts or diagrams that give you the enthalphy - pressure - temp contours for ammonia solutions. One source for this is Perry Chem Engg Handbook, chapter 2 (see fig 2-7 in the 7th edition)
To avoid 2 phase (vap / liquid) operation at the mixing nozzle, I would keep the operating pressure at above the bubble point pressure of pure ammonia, which would be approx 14-17barg or so.
There may a risk that a process simulation program may not model this chilling effect due to the heat of mixing correctly, so would suggest you do this by manual calcs to start with. If the chilling effect is too much, suggest using vapor ammonia and a packed column operating in countercurrent mode.
a)Heat of solution for ammonia is negative (i.e there is a chilling effect upon mixing, starting with pure ammonia in the liquid phase)
b) Choose an operating pressure for the mixing operation that will maintain the aqueous am. at above 0degC (say 10degC), so that water doesnt freeze
c) There is of course the auto - refrigeration effect when pure ammonia at high pressure is let down to the pressure of the mixing operation.
c)Refer to charts or diagrams that give you the enthalphy - pressure - temp contours for ammonia solutions. One source for this is Perry Chem Engg Handbook, chapter 2 (see fig 2-7 in the 7th edition)
To avoid 2 phase (vap / liquid) operation at the mixing nozzle, I would keep the operating pressure at above the bubble point pressure of pure ammonia, which would be approx 14-17barg or so.
There may a risk that a process simulation program may not model this chilling effect due to the heat of mixing correctly, so would suggest you do this by manual calcs to start with. If the chilling effect is too much, suggest using vapor ammonia and a packed column operating in countercurrent mode.
- Thread starter
- #6
georgeverghese
Chemical
Yes, the reaction is exothermic when you use vapor ammonia as the feed reactant, and is endo thermic when liquid ammonia is used.
It would be preferable to use vapor ammonia as feed, so we are looking at a packed absorber - cooling coils at some intermediate height in the packing will be required to remove the heat of dilution. Mass transfer coefficients and packing factors for ammonia absorption are published in the Norton packings catalogue for example.
It would be preferable to use vapor ammonia as feed, so we are looking at a packed absorber - cooling coils at some intermediate height in the packing will be required to remove the heat of dilution. Mass transfer coefficients and packing factors for ammonia absorption are published in the Norton packings catalogue for example.
- Thread starter
- #8
georgeverghese
Chemical
There are diagrams on the net for the packed tower setup, but they dont show the cooling coils. An experienced process engineer should be able to come up with the detailed PFD and calcs to determine the actual heat of dilution, the packed bed height, any liquid amm vaporisers and the cooling coils. As there are no inerts in this ammonia gas feed to the tower, and ammonia dissolution in the tower would be rapid, you may need a pressure makeup line to the top of the tower to maintain tower pressure, which you can arrange with an ammonia vapor feed slipstream going to the tower top. Nothing out of the ordinary for process controls.
georgeverghese
Chemical
My previous estimates on heat of dilution were in error; the reaction is still exothermic when liquid ammonia is used. For the following conditions (a) liquid amm at 20degC, P=>saturation pressure, (b) feed demin water at 20degC, (c) exit aqua amm at 25%wt,20degC, total heat to be removed is 46kcal/kg of aqua ammonia. Bubble pressure of this resulting solution at 66degC is approx 400kpa abs, so we could run this mixing operation at 500kpag or more. This then simplifies the system to a mixing nozzle for injection of pure liquid amm into a pipe running with demin water, a static mixer and a HX to cool the hot aqua ammonia from about 65degC to 40degC or so. For a final product at 40degC, in this case, HX duty would then be 25kcal/kg of aqua produced.
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