2 replies to this topic

[AnnaV]

Good day 

 

I need to evaluate the design for a CO2 degassing tower on a water treatment plant. A CO2 degasser, is required to remove CO2 post RO to increase pH. The supplier of the equipment have changed their design from two towers to one. The flow rate is quite variable (20-100m3/h). The air blower is on VFD so can be modulated to match the water flow rate.

 

The supplier informed me that the tower is now narrower and taller and this mitigates the need for two towers allows a higher flow variability. I understand that the risk was flooding at the lower flows. The slim but tall tower seems to mitigate this. I do know that in design calculations a narrower tower allows higher flow rates.. Can someone please explain why this is the case? Any concerns? 

 

Thank you 

 

 

[Pilesar]

So you have water stripped by air in a trayed tower... Flooding would occur if too much liquid were carried upward by the vapor to the tray above. Vapor velocity affects the tendency to flood. Also the distance between trays matters. In many columns, the vapor volume is highest at the bottom of the tower so the trays are spaced farther apart in the lower sections or the column diameter is sized larger to reduce vapor velocity. When designing columns, the usual goal is to 'right size' the equipment to optimize capital and operating costs while meeting the performance criteria. If you do not have distillation modelling software, you can download KG-Tower for free and simulate the tower yourself to quantify flooding concerns.

[breizh]

Hi,

More details about the tower will help! Can you share a PFD or PID with the details of internals (Trays /Packing)?

You should also check for the operating cost! Most probably you got a bigger motor to take into account the head loss due to the height. 

Breizh