Packed-bed and venturi scrubbers both put gas in contact with liquid — but they solve different problems, and picking the wrong one wastes either capture efficiency or fan power. Here is the decision in plain terms.
Packed-Bed: Built for Soluble Gases
A packed tower gives the gas a long, gentle ride through wetted packing surface. Residence time and surface area are what absorb soluble pollutants — HCl, HF, NH₃, SO₂, caustic mists — so the packed bed reaches 90–99% removal at a modest 300–800 Pa per stage. Its weakness: fine dust. Sticky or insoluble particulate rides the gas streamlines around the packing surfaces and eventually plugs the bed.
Venturi: Built for Particulate
A venturi accelerates the gas to 40–100 m/s through a throat and injects liquid into that shear zone, atomizing it into a dense droplet cloud that captures sub-micron particles by impaction. It is compact and self-cleaning — and it pays for that with pressure drop: 2,000–8,000 Pa is normal, which means real fan kilowatts, every hour, forever.
The Practical Rules
- Gas-phase pollutant, little dust → packed-bed tower. Lowest energy per unit of removal.
- Dust or fume is the target → venturi (or a filter, if the stream is dry and cool).
- Both at once → venturi first to knock out particulate, packed tower after for the soluble fraction. The classic two-stage train.
- Grease, fibers or bio-growth → packed tower with tellerette packing and generous washdown, not a tighter bed.
A Note on Materials
Whatever the geometry, acid service argues for plastics. We build packed towers and scrubber housings in PP as standard — immune to the chlorides that pit stainless — and fit PVDF internals where temperature or oxidizers demand more. Venturi throats, which see abrasive velocities, are the one place we still specify hard alloys or ceramics.
Unsure which side of the line your gas falls on? Describe the process over WhatsApp (+86 186 1558 6932) and we will recommend a train — including telling you honestly if a venturi from someone else belongs in front of our tower.