The following are the main challenges and corresponding solutions for the application of electrostatic precipitators in steel plants:
Problem Description: During smelting processes in converters and electric arc furnaces, the temperature, flow rate, and dust concentration of the flue gas can change drastically within very short periods (seconds). Particularly during stages like hot metal charging and oxygen blowing, large amounts of high-temperature flue gas rich in carbon monoxide (CO) are instantly generated. This not only imposes significant impacts on the dedusting system but also poses explosion risks.
1. Process Interlocking and Intelligent Control: The electrostatic precipitator must be deeply interlocked with the smelting process. By monitoring the smelting cycle in real time, it can anticipate and adjust fan airflow and electric field power in advance, achieving an intelligent operating mode of "slowing down to wait, and operating at full capacity during peaks" to smoothly handle the impact.
2. Explosion-Proof Design and Pressure Relief Devices: Sufficient explosion vents are installed on the precipitator body and ducts. Once internal pressure abnormally increases, they can rapidly relieve pressure, preventing equipment damage from explosion.
3. Emergency Cooling and Air Mixing Systems: Emergency air mixing valves or spray cooling systems are installed at the precipitator inlet. When flue gas temperature exceeds the limit, ambient air or water mist is immediately injected to force cooling and protect internal components.
Problem Description: Steel plant dust has a complex composition, including iron oxides (Fe₂O₃, Fe₃O₄), zinc oxide (ZnO), lead oxide (PbO), and oily substances from scrap steel. The resistivity of this dust varies greatly with temperature and composition, often falling within the high or low resistivity ranges that are most difficult for ESPs to collect, leading to reduced efficiency.
1. Flue Gas Conditioning: Injecting specific conditioning agents (such as ammonia) into the duct can effectively optimize the surface resistivity of the dust, bringing it within the optimal collection range of the ESP.
2. Broad-Temperature Design and Precise Temperature Control: Design the ESP to operate within the most suitable temperature window for different processes. For example, for dust rich in zinc oxide, avoid the temperature range where its resistivity is highest by using heat exchangers to cool the flue gas to a suitable temperature.
3. Adoption of New Power Supplies: High-frequency pulsed power supplies or three-phase power supplies can better adapt to changes in dust resistivity, providing a more stable electric field, and effectively suppressing back corona, especially when handling high-resistivity dust.
