In short: A venturi scrubber removes mainly particles and mists by accelerating gas through a throat. It reaches 70% to over 99% efficiency, but higher efficiency means higher pressure drop and energy. A packed bed scrubber mainly absorbs gases (for example HCl, NH₃, SO₂) at low pressure drop, with gas and liquid usually in counter-current flow. For dust plus acid gas, a venturi is often placed ahead of a packed bed.
How do they compare?
| Venturi scrubber | Packed bed scrubber | |
|---|---|---|
| Main target | Particulate matter and mists, including fine PM | Soluble or reactive gases |
| How it works | Gas accelerates through a throat and atomises the scrubbing liquid; droplets capture particles | Gas passes through wetted packing; pollutant transfers into the liquid |
| Removal efficiency (US EPA) | 70% to over 99% for PM, depending on design and pressure drop | High for soluble gases with the right liquid and packing depth |
| Pressure drop / energy | High; rises with the efficiency target | Low to moderate |
| Plugging risk | Handles dusty gas well | Packing can plug with solids |
| Typical FRP use | Corrosive, wet PM duty | Acid fume, ammonia and odor control |
When should you choose a venturi?
- Fine particles or mists: for example from dryers, kilns, incinerators or metal processes.
- Dirty, sticky gas: gas that would plug packing.
- Pre-treatment: to remove particles and cool the gas before a packed bed. US EPA notes venturis are sometimes used this way.
When should you choose a packed bed?
- Acid gases: HCl, HF and SO₂ with water or caustic.
- Ammonia and amines: with an acid scrubbing liquid.
- Odor: H₂S and mercaptans with caustic or caustic plus oxidant. See biofilter vs chemical scrubber.
- Low energy use: where particle loading is low.
See packed bed scrubber sizing and scrubber pH control and blowdown.
Do you always need a mist eliminator?
Yes. Both types carry droplets with the outlet gas, so a mist eliminator is fitted after them. See what is a mist eliminator.
How FIBROVX can help
Send us the gas flow, temperature, pollutants and their concentrations, particle loading and the required outlet limits. We will propose a scrubber type. Request a quote. CIF by default, FOB on request.
Common mistakes
- Using a packed bed for dusty gas: the packing plugs.
- Expecting a venturi to absorb gases well: it is mainly a particle collector.
- Underestimating fan power for venturis: pressure drop drives energy cost.
- No mist eliminator: droplets carry pollutant out of the stack.
Key terms
- Throat: the narrow section of a venturi where gas velocity is highest.
- Packing: media that creates gas-liquid contact surface.
- Counter-current: gas flows up while liquid flows down.
- Pressure drop: resistance the fan must overcome.
Watch: Venturi vs Packed Bed Scrubber in 27 Seconds
FAQ
Can a venturi scrubber remove acid gases? To some extent, but packed beds are much more effective for gas absorption.
What efficiency can a venturi scrubber reach? US EPA gives 70% to over 99% for particulate matter, depending on design and pressure drop.
Why combine a venturi and a packed bed? The venturi removes particles and cools the gas. The packed bed then absorbs gases without plugging.
Are FRP scrubbers suitable for both? Yes. FRP is widely used for corrosive wet scrubbers, within the resin's temperature limit.
Related guides
- FRP scrubbers guide
- Packed bed scrubber sizing
- What is a mist eliminator
- Acid fume scrubbers for plating and PCB plants
- Request a quote
Sources
- US EPA, Air Pollution Control Technology Fact Sheet: Venturi Scrubber (EPA-452/F-03-017): https://www3.epa.gov/ttncatc1/dir1/fventuri.pdf
- US EPA, Air Pollution Control Technology Fact Sheet: Packed-Bed/Packed-Tower Wet Scrubber: https://www3.epa.gov/ttncatc1/dir1/fpack.pdf