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Home   ›  APC Learning Center   ›  ESP Maintenance Tips   ›  Daily Observation   ›  Rappers

Electrostatic Precipitator Rappers

  • Why is the correct operation and setting of the rapper system essential to good Electrostatic Precipitator performance?
Maintain operation of the rappers. Always check (on a daily basis) that the rappers are operating. One of the best ways is to simply walk up on the roof of the ESP and listen to the rappers hitting. Loss of rapper operation will result in poor precipitator performance.

Both over rapping and under rapping will deter from optimal performance of the electrostatic precipitator.
  • Over rapping will cause re-entrainment resulting in poor ESP performance and high stack emissions.


  • Under rapping will cause an excessive amount of build-up on the collecting plates and discharge electrodes, which will reduce electrical power in the ESP thus resulting in poor ESP performance and high stack emissions.
  •   Heavy build up on the precipitator collecting and discharge electrodes are often a result of under rapping or rappers malfunction

  • Importance of maintaining rapper ground straps and boot seals
  •   The complete grounding of the rapper coil assembly and housing is essential to complete the entire grounding of the Electrostatic Precipitator. The shaft connections on the rappers are usually not sufficient to assure a complete ground to the rapper coils. Transient voltages can occur in the ESP and if the rappers are not properly grounded, these voltages can induce electrical surges into control and power cables, which may damage the controls. This is especially true with the high voltage discharge electrode rappers. These rappers are isolated by a shaft insulator. Any leakage through this insulator will bleed through to the rapper coil and it is obvious that a good ground connection is required to make sure that any transient voltage is grounded.

    During an ESP walk down, always make sure that the rapper ground straps are securely in place. These ground straps frequently break due to the impact of the rappers.
       Rapper boot seals are important to insure that no rain or cold air is allowed to enter the ESP. If the rapper boot seals are leaking, this will allow cold outside air to enter the ESP and create corrosion and possibly damage to the insulators.

    Always make sure that the rapper boot seals are in good condition and that the clamps are tight. Replace any boot seals that are torn or cracked. A small item such as a torn boot seal could cause a considerable amount of damage to an ESP.
     

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