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One solution for aging ESPs...

Retrofitting with rigid discharge electrodes (RDE)


A utility in Southern Africa has entered a period where many of their electrostatic precipitators are twenty (20) years old or older and require major upgrades or rebuilds. Because of new and more stringent emission limits, their final performance must exceed original design specifications. Yet due to competitiveness, the cost of these improvements is extremely important.

The utility contracted EPSCO to complete a study to determine the feasibility of improving the performance of the rigid frame designed ESPs at two plants.


The scope of the study addressed the following

  • Determine the SCA of the ESPs required to improve their performance to meet a 50 mg/Sm3 emission limit.
  • Could this improvement be accomplished by rebuilding the internals of the ESP and using the existing concrete casing.
  • Estimate the cost in South African Rand for the ESP upgrades.

EPSCO’s study concluded that rebuilding the ESPs using rigid discharge electrode (RDE) design instead of the existing rigid frame discharge system had the potential to increase the SCA by 30% or greater.

This concept, coupled with flue gas conditioning, would allow the units to achieve much lower outlet emissions than had been previously possible at a significant cost savings over complete replacement.



EPSCO ‘s study enabled the utility to conceptualize a new approach to ESP performance improvement. The study included layout drawings, weight estimates with preliminary load diagrams, structural analysis, customized electrode and rapper recommendations, itemized budget costs and time schedules. 







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