2 replies to this topic

[arturofast]

Team,

Good afternoon I'm coming to you with the following problem.

I'm designing a sparged vessel (bubble column) for sweetening a natural gas stream of 30 MMSCFD at 960 psig pressure and 100°F. I need to do just a polishing on the gas and knock down the H2S from 20 to less than 1 ppm. I want to get the system running 30 days, for this purpose I will use a Lead-Lag system in order to be able to isolate and reverse the flow during some hours for chemical change out. I'm using an amine based product.

I have designed sparge vessel in the past but at atmospheric pressures, at high pressure it is much more complicated for me.

I need to get a superficial velocity of 5 ft/min. When calculating the required vessel volume the diameter of the vessel is several times (20 times, 6ft diameter) bigger than the pipe that feeds the sparger manifold. I don't know how to manage the pressure, should I use the pressure of the incoming natural gas (960 psi) and the ACFM at this pressure, or do I need to calculate a new pressure due to gas expansion, and velocity changes. Or should I just concentrate on the liquid pressure and temperature in the vessel, and based the design on the liquid phase.

I really appreciate any suggestions on how to tackle this design

A. Fast

[Zauberberg]

Superficial velocity is calculated based on actual operating conditions (pressure, temperature) of the vessel. If bubble column operates at 960 psig, that's the pressure to be used for calculations. Sparger manifold will always be with smaller smaller than the tower since other criteria have been used for sizing.

[arturofast]

Zauberberg,

Thank you very much for you reply. I did calculations with the actual pressure and temperature. Just for reference results are the following:

Minimum calculated height: 4.30ft, selected height: 12ft, overall vessel height: 16ft
Minimum diameter at calculated height: 15.80ft, Minimum diameter at selected height: 9.46ft, overall diemeter: 11ft
Sparger area: 60ft2

The system will be comprised of a lead-lag system.
Height calculated from mass transfer (log []in/[]out)
Diameter calculated from superficial velocity (5 ft/min)
Selected height and diameter in order to fulfill customer specs of 30 days changeout
Overall vessel dimensions in order to fulfill safety factors 33% height and 15% diameter

AF