The invention relates to an environmental-friendly device of an iron and steel enterprise and a dust removal method, that is to say, a 
system and a method for treating converter 
flue gas. The 
system comprises a furnace mouth 
nitrogen injection sealing petticoat 
pipe, a segmental 
evaporation cooling 
flue, a high-temperature 
heat pipe steam generator, a spray 
evaporation cooler, a long neck adjustable 
throat venturi tube, an 
impeller type composite dehydrator, a fan, an automatic continuous 
coal gas detector and a three-way switching valve, which are connected in sequence, wherein the three-way switching valve is connected with a 
gas chamber; or the three-way switching valve is communicated with a 
chimney. The method comprises the following steps of: forming a soft sealing screen between a furnace mouth and a petticoat 
pipe, after segmentally vaporizing and cooling the 
flue gas, and cooling in a high-temperature 
heat pipe; after carrying out spray 
evaporation, cooling and rough dust removal through a dry method, carrying out fine dust removal and cooling by a venturi tube through a wet method, dehydrating the 
flue gas, and entering into a 
coal gas recycling stage lastly. According to the invention, the wet method and the dry method are combined, 
waste heat recovery, 
coal gas 
recovery, 
sewage treatment and dust removal can be planned in a 
flue gas treatment and utilization 
system as a whole and the combination action of the device is fully exerted.