The wet tubular electrostatic precipitator system is designed for applications where the standard dry plate type
The wet tubular electrostatic precipitator system is designed for applications where the standard dry plate type precipitators are not suitable. Both the tubular and poly-stage electrostatic precipitators operate on the same principle. In the poly-stage design, particulates are collected in the cell by electrically attracting them in the ionizing section (composed of plate and wires) and electrically attracting them to grounded parallel plates in the collection section. In the tubular design, the parallel plates comprising the collection section have been replaced by an "egg crate" grid of electrically grounded rectangular tubes. Each rectangular tube houses a solid electrode running the length of the tube, parallel to the grounded walls, and with coincidental longitudinal centerlines.
The electrode imparts a like negative charge on a particle as it begins to travel inside the tube. Repulsion forces (due to the likeness in charge) interacting between the electrode and thc particle, as well as forces of attraction between particle and grounded walls (grounded walls are "oppositely charged" as far as the particle is concerned), cause the particle to drift towards the walls of the tube where collection occurs. This "push-pull" effect is behind the electrostatic precipitators high collection efficiency and lower power requirements.
The solid electrodes virtually eliminate maintenance, since there are no broken wires to replace. Wider spacing, along with tubular configuration, lessens sparking and shorting of cells. Therefore, this design abates process exhaust, which contains high concentration of particulate. Lower pressure drops (0.25 in w.g. vs. 10-15 in. w.g.) and the elimination of broken or blinded bags makes this precipitator design highly desirable in lieu of fabric collectors. Wider tube spacing also enables the precipitator to operate continuously or intermittently wet.
By running intermittently or continuously wet, the unit is being washed while in operation.
Therefore, down time for washing is no longer necessary. If required, the cells can be cleaned by compressed air or rapping or shaking, in lieu of water or process liquor.
The tubular cell configuration lends itself to higher face velocities. For equal efficiencies, the tubular precipitator will be able to handle a greater volume of exhaust, thus a more compact design. This feature is magnified when the electrostatic precipitator is allowed to run continuously wet. Re-entrainment problems due to highly resistive or highly conductive materials have been eliminated by operating the precipitator wet. As soon as the particle adheres, it is swept away. Because of its insensitivity to wetness, the precipitator can be installed down stream from existing wet scrubbers, bringing these scrubbers into compliance with today's more stringent codes.
Beltran Associates Inc., 1133 East 35th Street, Brooklyn, NY 11210. Tel: 718-338-3311; Fax: 718-253-9028.