Glossary
KPIs and measurements
Removal efficiency
Also known as DRE, destruction and removal efficiency.
Removal efficiency is the fraction of a target pollutant removed by an emissions-control device, parallel to collection efficiency for particulate. Removal efficiency is the standard KPI for gaseous-pollutant control:
| Device | Target | Typical removal efficiency |
|---|---|---|
| SCR | NOx | 80–95% |
| SNCR | NOx | 30–60% |
| Wet FGD | SO₂ | 95–98% |
| Dry FGD (CFB scrubber) | SO₂ | 85–95% |
| Activated carbon injection | Mercury | 80–95% |
| Claus unit / SRU | H₂S → S | 95–99.9% (multi-stage) |
How fouling degrades removal efficiency
- SCR catalyst — masking and pluggage reduce active surface area
- Wet scrubbers — internal scaling and spray-distribution problems reduce gas-liquid contact
- AIG — fouled ammonia injection grids cause maldistribution
Sonic horns on SCR catalyst layers directly defend NOx-reduction efficiency.
Related terms
Related terms
- Collection efficiencyCollection efficiency is the fraction of inlet particulate captured by an ESP, baghouse or cyclone. Reported as a percentage; modern ESPs achieve 99.5%+, baghouses 99.9%+.
- Selective Catalytic ReductionSCR is the dominant NOx-control technology on industrial combustion plant. Ammonia is injected upstream of a catalyst that converts NOx to nitrogen and water.
- NOx reduction efficiencyNOx reduction efficiency is the percentage of inlet NOx removed by the DeNOx system. The headline KPI for SCR (80–95%) and SNCR (30–60%) operation.