Rappers

Particulate which accumulates on collecting electrode surfaces and on discharge electrodes must periodically be dislodged by rapping the collecting plates and discharge electrodes.  Rapping removes particulate to the hoppers for disposal and maintains both the discharge and collecting electrodes in an "operationally" clean condition for proper operation.

Hamon Research-Cottrell utilizes magnetic impulse gravity impact MIGI^® rappers on collecting plates and discharge electrodes.

The MIGI^® rapper is a simple electromagnetic coil that provides a controlled and adjustable lift for its one moving part, a 20 pound plunger.  Individual rapper operation is initiated by a controlled, short duration, low voltage (110 V d.c.) pulse. This pulse energizes the coil, generating a magnetic field that lifts the plunger into the phenolic guide tube. After the coil is de-energized, the plunger drops by gravity and impacts on a stationary rapper rod that transmits the forces to the ESP collecting plates and discharge electrodes.
Unlike a tumbling hammer (European) design, the MIGI^® rapper has no moving parts in the gas stream and is not exposed to the erosive effects of the flue gas and particulate.

The roof mounted MIGI^® design permits on-line inspection and servicing.  And, as service conditions change, both the frequency and the intensity of the rapping force can be easily changed from the rapper control panel.