Structure and classification of wet electrostatic precipitator

  • Date:2019-04-17
  • Wet electrostatic precipitators are available in several configurations. One is to use a corrosion-resistant conductive material (a non-metallic material with excellent electrical conductivity or a metal material with corrosion resistance), and the other is to use water spray. Or the overflow water forms a non-metallic material that is not conductive with a conductive water film as a dust collecting pole. Wet electrostatic precipitators can also be divided into cross-flow type horizontal type and vertical flow type (vertical type). The cross-flow type is mostly plate type structure, the gas flow direction is horizontally in and out, and the structure is similar to dry type electric precipitator; the vertical flow type is mostly In the tubular mechanism, the gas flows in and out in a vertical direction.

    In general, the efficiency of the vertical flow type wet electrostatic precipitator is twice that of the cross flow type under the same ventilation cross-sectional area. The dust that collects on the plates can be washed out with water. Wet cleaning can avoid the re-flying of the collected dust and achieve high dust removal efficiency. The operation is also reliable because there is no rapping device. The device for forming a conductive film on the surface of the dust collecting electrode by spraying water or overflow water has problems of corrosion, sludge and sewage treatment, and is only used when the dust concentration of the gas is low; when the dust containing efficiency is required to be high; Corrosion-resistant conductive materials The dust-type electrostatic precipitators do not require long-term water spray or overflow water. They are only periodically flushed according to the operating conditions of the system. Only a small amount of water is consumed. This part of the water can be recycled and recycled. No secondary pollution.

    The wet electrostatic precipitator and the dust collector of the dry type electrostatic precipitator have the same principle, and the dust is charged by the high voltage corona discharge, and the charged dust reaches the dust collecting plate/tube under the action of the electric field force. The dry electric precipitator mainly treats dry gas with very low water content, and the wet electric precipitator mainly treats wet gas with high or even saturated water. WESP and DESP are different in the dust removal method collected on the dust collecting plate/tube. The dry electrostatic precipitator generally removes the ash on the electrode by mechanical vibration or sonic cleaning, and the wet type The dust collector uses a regular flushing method to remove the dust as the flushing fluid flows.WESP has high dust removal efficiency, low pressure loss, simple operation, low energy consumption, no moving parts, no secondary dust, low maintenance cost, short production downtime, can work below the dew point of flue gas, and can be combined with compact structure.

    Other flue gas treatment equipments are combined with each other and the design forms are diversified. The wet electrostatic precipitator uses liquid to flush the surface of the dust collecting surface for cleaning, which can effectively collect fine particles (PM dust, SO acid mist, aerosol), heavy metals (Hg, As, Se, Pb, Cr) and organic pollutants ( Polycyclic aromatic hydrocarbons, dioxins, etc. After using the wet electrostatic precipitator, the smoke emission in the wet flue gas can reach 10mg/m or even 5mg/m. The dust collection performance is independent of the dust characteristics. It is suitable for the treatment of wet flue gas, especially suitable for power plants and steel mills. After the desulfurization, the dusty flue gas is treated, but the equipment investment cost is high, and it needs to be used together with other dust removal equipment. The investment technical economy and operating cost should be evaluated from the whole. 

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