Venturi scrubbers
A packed bed is built for soluble gases and will blind on solids. Where the contaminant is particulate — metal fume, dust, acid mist — the mechanism has to be inertial impaction instead, and that means putting energy into the gas.
- Metal fume
- Process dust
- Acid mists
- Sub-micron particulate
- Soluble gases
The principle
A venturi accelerates the gas stream through a throat at high velocity and injects liquor into it. The sudden shear atomises the liquid into fine droplets travelling much slower than the gas, and particles impact and are captured. Downstream, a cyclonic or packed separator removes the loaded droplets.
Efficiency is a direct function of pressure drop across the throat, so the design is an explicit trade between removal and running cost. We state both, and where a variable throat is worth having on a swinging load, we say so.
Inertial capture, not absorption
Removal comes from droplet impaction in the throat, which is what makes it effective on solids a packed bed would simply block.
Fixed or variable throat
A variable throat holds efficiency across a turned-down flow instead of over-scrubbing at part load and wasting fan power.
Separator to suit
Cyclonic separator as standard; a packed section instead where there is a soluble gas to take out as well as the particulate.
Built for abrasion
Throat and elbow materials selected for the duty, with wear parts arranged so they can be replaced rather than the vessel.
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 – 30,000 m³/h |
|---|---|
| Throat velocity | Typically 60 – 120 m/s |
| Pressure drop | Typically 2 – 10 kPa, set by the required efficiency |
| Throat | Fixed or variable, with manual or automatic adjustment |
| Separator | Cyclonic as standard; packed section where gases are also present |
| Body materials | 316L stainless, PP or rubber-lined steel |
| Particulate removal | High efficiency down to the low micron range |
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 concentrations agreed against permit or consent conditions before design freeze
- Fan and motor selected with the full wetted pressure drop accounted for
- DSEAR assessment where dust or solvent creates an explosive atmosphere
- 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.
SpecificationsPacked tower scrubbers
The workhorse for soluble gases — counter-current or cross-flow, from a few hundred to tens of thousands of cubic metres an hour.
SpecificationsOdour control scrubbers
Chemical scrubbing for hydrogen sulphide, mercaptans, ammonia and the amine odours that generate complaints.
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.