Flyash is a pernicious substance that seems to get into everything. On the electrodes, highly resistive ash will build a coating an inch or more in diameter, dampening the electrode’s corona discharge. When ash coats a high tension support insulator, as is shown in the diagram to the left, current can flash across the ash, shorting out the electrical field.
A solution has been model tested for that problem, optimizing cleaning while using minimal ambient air. The diagram at the center demonstrates what happens when the gas stream is directed into a hopper. Two prominent causes of this are shortening or removal of the hopper divider baffle and shortening of the perforated plate at the intake plenum. The diagram at the right shows a number of problems that can happen to an unwary plate rapper. Without functioning plate rappers, the collector plates will become caked with ash. Note that the weld has broken at the plate anvil. The rubber boot seal is gone, which has allowed ambient air to corrode the shaft solidly to the penetration at the penthouse floor. This rapper can rap all it wants and all it will make is noise.