Increasing the precipitation area through an additional field or by switching the internals of an ESP is a proven but costly way to reliable lower the clean gas dust concentration. The modernization of the high-voltage supply and controller can under favorable circumstances lower the clean gas dust concentration in a more cost-effective way.
If the process parameters are favorable, more energy input into the electrical field will result in a lower clean gas concentration. An increase in the voltage and the current in the field will improve the charging of the particles and increase precipitation performance and efficiency.
Modern digital high-voltage controllers can react faster to changing situations in the electrical field and keep the electrical parameters high longer. Another advantage is the operation near the flash over point and the more dynamic response of the controller, especially upgrading from an analog to a digital one.
3-phase or high-frequency switch mode power supply (SMPS) technology improve the electrical parameters in the field. Pulse modes or special pulse units improve the electrical charging of the dust particles under challenging process conditions and can lower the clean gas concentration.
In Table 1 an ELEX ESP is upgraded from 1-phase technology to high-frecuency (SMPS) technology, an optimization of the process and electrical parameters was performed after the installation.
| Field, avg. [kV] |
Power, avg. [kW] |
Clean gas concentration [mg/Nm3] |
|
|---|---|---|---|
| Existing | 35.7 | 17.5 | 14.49 |
| After upgrade | 57.3 | 77.6 | 3.63 |
| After upgrade, optimized | 51.4 | 48.4 | 4.76 |
Table 1: Upgrade of 1-phase technolgy to high-frequency (SMPS) technology, waste incineration, Switzerland
