Wet Electrostatic Precipitators

These multi-stage, tubular-design systems are able to control emissions at the submicron level, including acid mists, submicron particulates and condensed organics.



Beltran Wet Electrostatic Precipitators (WESPs) are utilized in various metallurgical processes, such as zinc, lead, gold and molybdenum roasting plants, nickel and copper flash smelters, and sulfuric acid regeneration plants, as well as sulfuric acid mist tail gas cleaning plants. Beltran has over 1,000 installations worldwide.

Performance Principles of Operation

Beltran Technologies’ Wet Tubular Electrostatic Precipitator System has been developed for applications for which 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In the Tubular design, the parallel plates comprising the collection section have been replaced by an "egg crate" grid of electrically grounded rectangular tubes.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 the 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 precipitator’s high collection efficiency and lower power requirements.

Features

The solid electrodes virtually eliminate maintenance, since there are no broken wires to replace.

Wider spacing, along with tubular configuration, greatly lessens sparking and shorting of cells. Therefore, this design will effectively abate 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 downstream from existing wet scrubbers, bringing these scrubbers into compliance with today's more stringent codes.

Due to the high efficiency of the precipitator, pressure drops across an existing high-energy scrubber (such as a Venturi) can be lowered. Dramatic energy savings are thus realized while upgrading the system's performance.

Beltran can supply an optional scrubber (or carbon bed) in combination with the precipitator. This will enable the system to control gaseous as well as particulate emissions.

Although aluminum and steel are the standard materials of construction, the cells and the precipitator can also be constructed of corrosion resistant material. These include stainless steel, fiberglass reinforced plastic (including the cells), or exotic metals such as zirconium or titanium.