I am a newbie on this forum. My mother languages is Dutch and my English isn’t very good, but I give it a try.
I would like to design a adsorber for drying wet compressed air.
The total air current (to be dried) is 80 m3/h (referred to 35 °C and 8 bar(a)).
The desirable pressure dewpoint is -40 °C by a temperature of 35 °C.
During a adsorption process of 4 hours, there should be removed 10,76 kg. H2O to reach the desirable pressure dewpoint.
I would use the desiccant Activated Alumina 2-5 mm.
I did the following assumptions:
The flow velocity referred to the open cross-section of the adsorber: 0,15 m/s ("Separation Processes (Jean-Pierre Wauquier)" --> Between 0,1 and 0,3 m/s for gases)
The effective capacity of Activated Alumina: 7 kgH2O / 100 kg. Activated Alumina ("Separation Processes (Jean-Pierre Wauquier)" --> Between 4 and 7 kgH2O / 100 kg. Activated Alumina)
Calculations:
> From the air current and the flow velocity, we can calculate the diameter of the adsorber: 0,434 m.
> Next we can calculate the needed mass of adsorbent: (10,76/7)*100 = 153,71 kg. Activated Alumina.
> With a bulk density of 752 kg/m3 we have a adsorbent volume of 0,20 m3.
> This results in a bed height of 1,35 m. and a L/D ratio of 3,12 which is between the recommended ratio of 1 and 4 for gases)
My questions about this:
- Is this a correct calculation (Assuming that the assumptions are correct)?
- Where can I find/calculate the effective contact time between air and adsorbent?
- I’ve did a assumption about flow velocity, but how can I calculate the actual needed flow velocity?
- Can anyone tell me where I can find the effective capacities of different desiccants? And where is this capacity depended on?
- How can I calculate the operating pressure-drop of the adsorption process?
- Can anyone give me tips or something which I can take into account?
Kind regards,
Niels