Gas Flow Distribution

Gas flow through the ESP chamber should be slow and evenly distributed through the
unit. Gas velocity is reduced by the expansion, or diverging, section of the inlet plenum
(Figure). The gas velocities in the duct leading into the ESP are generally between 12
and 24 m/s (40 and 80 ft/sec). The gas velocity into the ESP must be reduced to
0.6-2.4 m/s (2-8 ft/sec) for adequate particle collection. With aspect ratios of 1.5, the optimum
gas velocity is generally between 1.5 and 1.8 m/s (5 and 6 ft/sec).

Gas inlet with perforated diffuser plates

In order to use all of the discharge and collection electrodes across the entire width of the
ESP, the flue gas must be evenly distributed. The inlet plenum contains perforated openings,
called diffuser plate openings to evenly distribute the gas flow into the chambers
formed by the plates in the precipitator.