4 replies to this topic

[ChemEng_CristianoB]

Good day to everyone, I am designing an absorption column to remouve methanol from a CO2 stream at 50 bar and 35°C with water.
I have no experience regarding absorption columns, so I would like to ask you for two pieces of advice:

• generally what velocity should the gas have inside the column (I just need the order of magnitude)?
• what filling do you recommend? Are IMTPs okay?

Thanks,
Cristiano

[Nikolay_]

Hi, it depends on absorbent flow. Search for how to calculate delta P per hight packing (initinal flooding).

[carlos infante]

Fisrt defined the process conditions of absortion

 

Flow rate  gas and absorbent fluid

Fraction of methanol in the CO@ stream outlet

calcutated the absortion bed requierements and pressure drop

 

IMTP is a packing normaly used in absortions columns

 

 

Carlos

[breizh]

Hi,

Consider this resource.

Breizh

Attached Files

•  Packed Bed.pdf   2.09MB   6 downloads

[ChemEng_CristianoB]

Thank you all for the answers.
I have one more doubt to ask.
First let me give you the conditions of the absorption process:
Temperature = 35°C;
Pressure = 48 bar;
CO2 flow rate (containing 1%w/w methanol): 2000 kg/h
Water flow rate: 200 kg/h.
Numeo of theoretical stages: 10.

In this way, according to both the simulator (ChemSep) and my calculations I can achieve effective methanol removal.
Regarding the diameter, following the flooding graphs, I must have a column with a diameter of about 30 cm. With this diameter, the gas velocity (density about 113 kg/m3) is 0.06 m/s.
I know that in an absorption column, to have a good mass transfer the gas velocity must be 0.3 to 0.6 m/s (to which, under my conditions corresponds a column diameter of 10 to 15 cm).
Could it be that working at rather high pressures for an absorption process (and consequently the density of the gas phase has a much higher density) the graphs for diameter calculation give me higher diameter values than necessary?