Description of the problem: When burning specific coal (such as low sulfur coal), the specific resistance of fly ash is too high (> 10^11 Ω·cm). Dust particles can't release charge smoothly after being charged, and an insulating layer is formed on the dust collecting electrode plate, resulting in local reverse discharge (back corona), which destroys the stability of electric field and leads to a sharp decline in dust removal efficiency.
1. Flue gas conditioning system: accurately spray sulfur trioxide (SO) or ammonia (NH) into the flue, effectively reduce the specific resistance of the dust layer, and fundamentally eliminate the back corona phenomenon. This is one of the most direct and effective means to deal with dust with high sulfur content and high specific resistance.
2. High-frequency pulse power supply: adopt new high-frequency pulse power supply technology. It provides extremely high peak voltage and extremely narrow pulse width, which can not only give enough charge to the dust, but also avoid forming too high voltage drop on the dust layer, thus significantly inhibiting the back corona and improving the collection efficiency.
Problem description: There is a "penetrating window" for the collection efficiency of fine particles (PM2.5) in the range of 0.1-1 micron by traditional electrostatic precipitator. These inhalable particles are the culprit of environmental pollution and health hazards, and also the key and difficult point to achieve "ultra-low emission".
1. Low-temperature electrostatic precipitator technology: A flue gas heat exchanger (MGGH) is installed in front of the electrostatic precipitator to reduce the flue gas temperature from the conventional 120-150℃ to about 90℃. Low temperature can significantly reduce the velocity of flue gas, increase the adhesion of dust and reduce the volume of flue gas, thus greatly improving the collection efficiency of fine particles and simultaneously removing SO.
2. Electric bag composite dust collector: organically combine electrostatic dust collector and bag dust collector. The former electric field captures 80%-90% of coarse particles, and the latter bag filters all the remaining fine particles. This technology combines the advantages of both, and the emission concentration can be stably controlled below 10 mg/m or even 5 mg/m, which is a reliable technical route to achieve ultra-low emission.
