May I ask: does the flue gas emitted from coking ovens contain coal tar? How is dust handled?
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I would like to ask the following questions: 1. What are the approximate components of coking off-gases? Apart from sulfur dioxide, CO, N2, and about 4% oxygen, are there any other gases present? In particular, are there any oily components such as coal tar?； 2. What type of dust collector is used to handle the dust in the off-gas after coking? Are electrostatic precipitators more common or bag filters? 3. What is the domestic emission limit for dust in the off-gas after coking, in mg/Nm3? Is it 30 or 50 mg? Thank you very much.
Gas naturally contains coal tar, benzene, and other substances. Coking workshops generally have dust removal equipment such as ground-based dust removal stations and smoke and dust removal vehicles.
Thanks to the person above. Just now, when rating, I clicked on fewer options than necessary. My apologies. Also, for the dust removal station you mentioned, what type of dust collector is being used? Because if an electrostatic dust collector is used, its effectiveness in removing this type of dust doesn’t seem very good, does it? If a bag filter is used, will substances such as tar and benzene in these flue gases cause the bags to stick together?
The waste gas generated by coke ovens during the coke extraction process contains substances such as coal tar, but it is different from the coal tar present in gas in the ordinary sense: initially, during coke extraction, the amount of gas produced is very small, while it is relatively higher when charging coal. Its main pollutant should be dust. For dust removal in coke ovens, ground-based dust removal stations are commonly used; currently, smoke-guiding dust removal vehicles and bag filters are more frequently employed. Due to the high temperature at which coke is discharged and the combustion that takes place within these dust removal vehicles, coal tar no longer adheres to the bags.
Thank you very much. I find that I can only give a little wealth; I don’t know why, I’m sorry. Based on your answer, may I understand that the flue gas after coking and dust removal on the ground can be directly discharged into the chimney? At this point, the tar content in the flue gas is very low, and if the temperature is high enough (200°C), there will be no sticking of the filter bags? (The temperature of 200°C was added by me; I remember that after coking, the temperature was around 250°C. I’m not sure if this is correct.)
Based on the conditions in our company, the treated flue gas is discharged from the exhaust stack of the dust removal system, but the exhaust temperature is not as high as 200 degrees. The dust removal system is cooled.