Electrostatic precipitators
ESP field
Also known as bus section, ESP bus section, electrical field (ESP).
An ESP field (also called a bus section) is an independently energised electrical zone of an ESP, with its own transformer-rectifier (T-R) set, discharge electrodes, and rapper group. Large ESPs are built up from multiple fields in series along the gas-flow direction.
Typical configuration
| Configuration | Use case |
|---|---|
| 3 fields in series | Small industrial ESPs |
| 4–5 fields in series | Coal-fired utility boilers, cement kilns |
| 6+ fields | Strict particulate limits, low-sulphur coal, WtE tail-end |
Fields are numbered from inlet to outlet. The inlet field sees the highest dust load and works hardest; the outlet field handles the residual particulate and runs near maximum sustainable voltage.
Why fields matter for cleaning
Each field is electrically independent: a sparking or back-corona-suppressed field can be isolated without shutting down the whole ESP. Dust load also differs along the gas path — inlet fields need aggressive cleaning, outlet fields less so. Multi-zone sonic-horn sequencing groups horns by field and matches firing intensity to local fouling.
Related terms
Related terms
- Electrostatic precipitatorAn ESP removes particulate from flue gas by charging dust and collecting it on plate electrodes. Sonic horns are widely used to dislodge ash from plates and to keep hoppers from bridging.
- Collecting electrodeThe collecting electrode is the grounded plate or tube on which charged particulate accumulates inside an ESP. Dust must be released to hoppers without re-entraining into the gas stream.
- Discharge electrodeThe discharge electrode is the high-voltage electrode that generates the corona discharge inside an ESP. Charged dust drifts from it to the collecting plates.
- Corona dischargeCorona discharge is the electrical breakdown around an ESP's discharge electrode that ionises gas molecules and charges dust particles for collection.