Packed tower scrubbers
Where a gas dissolves or reacts readily in the scrubbing liquor, a packed tower is the most efficient way to remove it. Contaminated air passes up through a wetted bed while liquor flows down against it, and the transfer happens across an enormous surface area of film.
- HCl
- HF
- HBr
- SO₂
- NH₃
- Cl₂
- H₂S
- Amines
- Formaldehyde
The principle
Counter-current is the default: the cleanest gas meets the freshest liquor at the top of the bed, which is what drives the last few percent of removal. Cross-flow towers earn their place where headroom is short or the dust load would blind a vertical bed.
Sizing is a calculation, not a selection. Gas velocity through the packing, liquid-to-gas ratio, bed depth and reagent strength are set against your gas composition and the discharge concentration you have to meet.
Sized against your duty
Bed depth, L/G ratio and packing type are calculated from your inlet concentration and required outlet, then stated on the datasheet.
Counter-current or cross-flow
Vertical counter-current for maximum removal per metre of bed; horizontal cross-flow where headroom or particulate loading rules it out.
Materials matched to the chemistry
Polypropylene, PVC, PVDF, GRP or 316L stainless, chosen for the gas, the liquor and the operating temperature.
Maintainable by design
Removable mist eliminator, access to the spray header, sample points and drain-down that one person can actually do.
Design envelope
Indicative ranges for this system type. Your figures are calculated against your duty and issued on a datasheet before anything is built.
| Duty range | 500 – 60,000 m³/h |
|---|---|
| Arrangement | Vertical counter-current or horizontal cross-flow |
| Gas velocity | Typically 1.5 – 2.5 m/s through the packed section |
| Liquid-to-gas ratio | Typically 1 – 3 litres per m³, set by duty |
| Packing depth | Typically 900 – 2,400 mm, in one or more beds |
| Body materials | PP, PVC, PVDF, GRP or 316L stainless |
| Removal efficiency | 95 – 99.5% on soluble gases, single stage |
| Pressure drop | Typically 400 – 1,200 Pa across the wetted bed |
| Mist elimination | Chevron blade or mesh pad |
What it is built to
Equipment is one part of a duty holder's obligations. These are the standards and regulations we design this system type against — your own risk assessment and permit conditions still govern.
- Discharge sized against the site’s environmental permit or consent conditions
- Ductwork specified to BESA DW/144 where we supply it
- DSEAR assessment and ATEX-rated equipment where a flammable atmosphere is credible
- UKCA marked to the Supply of Machinery (Safety) Regulations 2008
Other systems
Compact fume cupboard scrubbers
Packed-bed scrubbers sized for one to four fume cupboards, built to fit the plant room you already have.
SpecificationsOdour control scrubbers
Chemical scrubbing for hydrogen sulphide, mercaptans, ammonia and the amine odours that generate complaints.
SpecificationsVenturi scrubbers
High-energy scrubbing for particulate, fume and sub-micron mists that a packed bed will not hold.
SpecificationsTell us the duty and we will size it
Send the gas composition, the flow and the discharge condition you have to meet. We will come back with what will work and what it will take out — and say so plainly if this is the wrong system for the job.