Treatment of dust in flue gas
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Bag dust collection and electrostatic dust collection are the two main methods for treating flue gas dust at present, each with its own characteristics. As environmental regulations become increasingly strict and the requirements for dust emissions grow more stringent, bag dust collection proves to have its advantages. It can achieve dust emission levels of less than 50 mg/m3, operates stably, requires minimal routine maintenance, and features a high degree of automation – advantages that make it superior to electrostatic dust collectors. As a result, bag dust collection is being used more and more widely. Regarding bag dust collectors, I believe the main issue is that although the initial investment is lower than that of electrostatic dust collectors, the maintenance costs are high, especially regarding the replacement of the filtering media; this is particularly true when imported filtering media are used. It is hoped that domestic alternatives can replace imports in order to reduce costs. At present, bag dust removal technology is continuously improving; in terms of dust collection, filtration media, and ash removal, it is comparable to foreign technologies. There are many manufacturers, each with its own unique techniques.
However, bag dust collection is not as advantageous as electrostatic dust collection when it comes to handling large volumes of flue gas or high-temperature flue gas.
Yes, the amount of smoke is high, so the filtration area must be large as well; this results in a larger footprint, and accordingly higher investment and maintenance costs. However, it still has advantages in terms of dust removal efficiency. For high-temperature flue gas, both electrostatic precipitators and bag filters have temperature requirements; if the temperature is too high, it is necessary to cool the gas first before dust removal can take place.
That makes sense; theoretically, the flue gas emission from bag filters can reach 50 mg/m3, while electrostatic precipitators can only achieve 100 mg/m3.
Bag filter dust removal efficiency is higher than that of electrostatic precipitators; with increasing requirements for dust emissions and improvements in bag filter materials, bag filters hold even broader prospects.
I heard that **the smoke emission limit is to be reduced from 50mg/m3 to 30mg/m3; as a result, the advantages of electrostatic dust collectors will disappear completely, and bag filters will become increasingly widely used.