Multi-stage scrubbers
Real process extract is rarely one gas. When the stream carries acidic and alkaline components together, or a particulate load ahead of a soluble gas, a single stage forces a compromise — and the compromise is always paid for in outlet concentration.
- Mixed acid gases
- NH₃ with HCl
- Particulate with soluble gas
- Solvent mists
- H₂S
The principle
Staging removes that compromise. Each stage runs its own liquor circuit, its own chemistry and its own control loop, and each is sized for the fraction of the duty it actually has to do.
Stages are ordered by what protects what: particulate removal ahead of any packed bed, acid before alkaline where ammonia is present, and oxidant last where the residual is a trace sulphur compound.
Independent liquor circuits
Separate sumps, pumps and dosing per stage. Nothing cross-contaminates, and one stage can be taken down for service without losing the other.
Staged sizing
Each stage is calculated for its own share of the removal, so you are not paying for bed depth that is doing nothing.
Interstage sampling
Sample points between stages, so performance can be proved stage by stage at commissioning and during operation.
One control system
All stages on a single panel with a common alarm and BMS interface, rather than a set of unrelated skids.
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 – 50,000 m³/h |
|---|---|
| Stages | Two or three, in series, each independently controlled |
| Typical stage 1 | Particulate removal or acid stage for alkaline gases |
| Typical stage 2 | Caustic stage for acid gases |
| Typical stage 3 | Oxidant stage or activated carbon polishing |
| Body materials | PP, PVDF, GRP or 316L, selected per stage |
| Overall removal | 99%+ achievable on mixed soluble streams |
| Sampling | Isokinetic-capable sample points at inlet, interstage and discharge |
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.
- Performance demonstrated stage by stage at commissioning, against an agreed test method
- Reagent systems segregated, bunded and separately labelled
- DSEAR and ATEX assessment where solvent or flammable gas is present
- UKCA marked; supplied with a full O&M manual and P&ID set
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.