Velocity non-uniformity issue inside Electro-static precipitators (ESP)
- Pradeep Sahu
- Jul 16
- 2 min read
Updated: Jul 21
Electro-Static Precipitators (ESPs) remove particulate matter from a gas stream by a series of corona generating electrodes and collector plates.
Several factors like flow rate, particulate size, particulate loading, voltage difference, hopper design affect the collection efficiencies in ESPs. The ESP under consideration is expected to have higher penetration of particles than the design requirement. It can be due to multitude of factors stated earlier. However, to ensure a better performance of the Electro-Static Precipitators, ICAC-EP7 has provided guidelines about flow uniformity. This CFD Analysis has been conducted to observe any non-uniformity in the flow field.
The Open Area Ratio (OAR) for Gas Distribution Screens (GD-Screens) are provided in the below image.
An important decision variable when it comes to ESP is the velocity distribution over the entry and exit of all ESP Chambers. A velocity contour plot (as one below) can show the variation of velocity magnitude.
Higher velocity regions are observed in the center of the chambers. The velocity decreases from the centre towards the chamber walls. This indicates a non-uniform distribution of flue gas at the gas distribution screen. The Institute of Clean Air Companies – EP7 (June 2004) prescribes two conditions (provided in the below table), for ESP gas velocity distribution. These conditions are related to the uniformity of velocity as flow enters and exits different chambers of the ESP. The deviation of velocity values from mean can be visualized as shown in below contour.
A value closer to mean indicates µ0 = 0. Hence, the above contour plot clearly represents higher deviations at the centre of chambers entries.
