Ruilong Popular Science | Introduction to Electrostatic Precipitator Equipment

An electrostatic precipitator is an environmental protection device that achieves efficient dust removal through a high-voltage electric field, widely used in industries such as power generation, steel, and cement. The following provides a detailed introduction from aspects including working principle, structural design, technical features, application scenarios, and development trends:

A high-voltage direct current is applied between the cathode and anode of the electrostatic precipitator, forming an electrostatic field strong enough to ionize the gas. The electrons, negative ions, and positive ions generated after gas ionization attach to dust particles passing through the electric field, charging the dust. The charged dust moves toward the electrode of opposite polarity under the electrostatic force and deposits on the electrode, achieving the separation of dust and gas. Then, by vibrating the electrodes, the dust falls into the ash hopper, achieving dust collection. Therefore, the dust removal principle of dry ESP involves three stages: charging, collecting, and ash cleaning.

A high-voltage direct current is applied between the cathode and anode of the electrostatic precipitator, forming an electrostatic field strong enough to ionize the gas. The electrons, negative ions, and positive ions generated after gas ionization attach to dust particles passing through the electric field, charging the dust. The charged dust moves toward the electrode of opposite polarity under the electrostatic force and deposits on the electrode, achieving the separation of dust and gas. Then, by vibrating the electrodes, the dust falls into the ash hopper, achieving dust collection. Therefore, the dust removal principle of dry ESP involves three stages: charging, collecting, and ash cleaning.

1. Dust Collection Electrode System (Anode):

Function: Collect charged dust particles.

Form: Usually composed of a series of parallel metal plates, with various groove shapes (such as C-type, Z-type, etc.) designed to increase stiffness and dust collection area.

2. Discharge Electrode System (Cathode):

Function: Generate corona discharge to charge the dust.

Form: Metal wires suspended between dust collection plates, such as barbed wire, star-shaped wire, spiral wire, etc. Barbed wire is widely used due to its high discharge intensity and large corona current.

3. High Voltage Power Supply System:

Function: Provide the high-voltage direct current required for corona discharge in the electrostatic precipitator. This is the "heart" of the ESP.

Composition: Includes high-voltage control cabinet, step-up transformer (T/R), rectifier, etc. Modern ESPs generally use intelligent high-frequency power supplies that can automatically optimize voltage and current according to flue gas conditions, saving energy and improving dust removal efficiency.

4. Vibration Ash Cleaning System:

Function: Remove dust accumulated on the anode plates and cathode wires.

Method: Usually uses top electromagnetic hammer vibration or side rotary hammer vibration.

5. Shell and Ash Hopper

Shell: A large steel structure that houses all internal components and forms the flue gas channel, requiring airtightness.

Ash Hopper: Located at the bottom of the shell, used to collect dust fallen from vibration. Equipped with a level meter inside and ash discharge devices at the bottom (such as star-shaped ash discharge valve, screw conveyor).

6. Air Inlet and Outlet Flow Distribution Plates:

Function: Ensure that dust-laden gas flows evenly enter the entire electric field cross-section, avoiding the formation of airflow corridors, which is a key auxiliary device to ensure efficient dust removal.

1. Advantages:

High dust removal efficiency: Has very high capture efficiency for fine dust (including PM2.5), usually reaching over 99.5%, and even up to 99.99%.

Large flue gas handling capacity: Can handle millions of cubic meters per hour of high-temperature, large-volume flue gas.

Low operating resistance: The pressure drop of flue gas through the ESP is usually only 100~300 Pa, so the main fan energy consumption is relatively low.

High temperature resistance: Can handle flue gas temperatures from 250°C to 450°C or even higher.

Relatively low operating cost: Although the initial investment is high, the low resistance results in lower long-term energy consumption.

2. Disadvantages:

Complex equipment with high management and maintenance requirements.

High precision requirements for manufacturing and installation.

Coal-fired Power Plants ：

This is the core application scenario of electrostatic precipitators. Used to capture fly ash generated by coal-fired boilers, it is a key device to ensure that power plant chimney emissions meet standards. Modern large coal-fired units are usually equipped with high-efficiency electrostatic precipitators, with dust removal efficiency reaching over 99.9%.

Steel Industry ：

▶ Sintering machine head/tail dust removal: Handles large amounts of dust generated during sinter production.

▶ Blast furnace iron tapping area dust removal: Captures dust generated during blast furnace iron tapping and iron discharge.

▶ Converter secondary dust removal, steelmaking electric furnace dust removal: Handles high-temperature dust generated during steelmaking.

▶ Rolling heating furnace dust removal.

Non-ferrous Metal Smelting ：

Pyrometallurgy: Dust control for smelting furnaces, reverberatory furnaces, and converting furnaces of metals such as copper, aluminum, lead, zinc, etc., while also recovering valuable metal particles.

Electrolytic Aluminum: Used to capture fluorine-containing flue gas and dust generated by aluminum electrolysis cells.

Cement Industry ：

Cement kiln head/tail dust removal: This is the main dust source in cement production. The flue gas has characteristics of high temperature, large humidity variation, and strong corrosiveness. Electrostatic precipitators or "electrostatic bag composite dust collectors" are very commonly used.

Coal mill dust removal, cement mill dust removal.

Coke Industry:

Dust control during coal charging and pushing in coke ovens.

1. Regular Inspection ：

During major overhauls, the distance between the anode and cathode must be calibrated (deviation ≤ ±5mm), and the vibration acceleration must be checked (anode plate ≥ 356G).

Use infrared thermal imaging to monitor the temperature of insulation components to prevent condensation and creeping discharge.

2. Optimize operating parameters:

Adjust the vibration cycle according to the coal type (usually 30-120 minutes) to avoid secondary dust emissions.

Dynamically match flue gas flow through an intelligent control system to operate the electric field at the optimal spark frequency (10-60 times/minute).

Policy guidance: The state encourages the adoption of technologies such as mobile electrodes and wet electrostatic precipitators, providing tax incentives and electricity price subsidies to enterprises that meet ultra-low emission requirements.