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Air Quality Control Systems (AQCS)Electrostatic Precipitators (ESP)

  • Maximum Capacity

    1,050 MW

  • Lowest Dust Emission

    Dry ESP : ≤ 10mg/m3N
    Wet ESP: ≤ 1mg/m3N

  • Wide Application Range

    ⋅ Moving Electrode Type ESP
    ⋅ Pulse Energization

  • High Reliability

Electrostatic precipitators (ESP) collect dust in the flue gas produced by boiler, etc. Mitsubishi Hitachi Power Systems (MHPS) contributes to air pollution control at thermal power plants, steel plants , and various industrial plants.

Basic Principle of ESP

A high voltage is applied to the discharge electrode, generating a corona discharge that produces minus ions. The electrically charged dust is accumulated on the collecting electrode by an electrical field.
The accumulated dust is removed by rapping hammer (dry ESP), scraping brush (dry ESP), or flushing water (wet ESP).

Dust Collection Performance and Dust Characteristics

Our accumulated know-how in evaluating characteristic assessments on various dust properties and flue gas conditions, together with extensive field experience, are reflected in the ESP design.

ESP Performance Improvements to counter High-Resistivity Dust

The most important consideration in ESP for coal-fired boiler applications is to maintain and increase the dust collecting performance of high-resistivity dust. Several improvements to counter high-resistivity dust have been established based on the investigation into the mechanism of back corona phenomenon.
Our technologies are shown in the following table. We can offer suitable technologies for plant applications and operations and can realize both compact design and high efficiency.

Countermeasure Method Our Technologies
(1) Dust layer Removal Removing Dust on Electrode Completely Moving Electrode Type ESP
Wet ESP
(2) Resistivity Decreasing Decreasing Gas Temperature High Efficiency AQCS (Low Low Temp. ESP)
(3) Current Control of Dust layer Electrical Energization Control Intermittent Energization
Pulse Energization

Mechanism to Remove Dust Collected on Collecting Plate

Fixed-electrode type ESP and moving-electrode type ESP use the following method to remove collected dust.

Fixed Electrode Type

Fixed Electrode Type

A collecting electorode rapping device is used to remove the dust collected on the collecting electrode.

Moving Electrode Type

Moving Electrode Type

Collecting electrodes are divided into short strip elements that are joined by chains, and the collecting electrodes are moved slowly.
The dust collected on the collecting electrode elements is completely scraped off by brushes provided in the hoppers.

Structure of Fixed Electrode Type ESP

External Structure

Internal Structure

Video: Fixed Electrode Type Electrostatic Precipitator

Moving Electrode Type Electrostatic Precipitator (MEEP)

Effective Collection of High-Resistivity Dust

Mitsubishi Hitachi Power Systems' (MHPS) moving electrode electrostatic precipitators incorporate a new system developed to dislodge collected dust by movable collecting plates and brushes.
These systems are also compact thanks to their high collection performance.

Structure of Moving Electrode Type ESP

Video: Moving Electrode Type Electrostatic Precipitator

Features of Wet Electrostatic Precipitator

  • Suitable for applications requiring a much higher degree of gas purity at outlet than can be readily achieved by dry type ESP.
  • Using water in removing the collected dust, the wet type ESP can achieve high dust removal efficiency (down to 1 mg/m3N) without being affected by the high or low electrical resistivity of dust.

Structure of Wet Type Electrostatic Precipitator

Video: Wet Electrostatic Precipitator

Inquiries Regarding Air Quality Control Systems (AQCS)