It is not clear whether you are looking for a packed scrubber or something else.
Also, whether you are using phase-separation only (as mucour suggests) or other process, maybe absorption or chemical reaction with absorption.
I have done reasonable work on packed scrubbers with absorption and...
As a thumb-rule, vapor velocities are limited to 30 m/s and keeping the dP less than 0.113 bar/ 100 m.
Also, liquid velocities are limited to 3 m/s but to 1.5 m/s for corrosive services.
The above are general guidelines and should be evaluated for the case considered.
For 2-phase flows, erosion...
