Furnace flue gas capture technology At present, the matured method of furnace flue gas capturing are semi-closed cover type and diversion roof cover type. The diversion roof cover is actually combined by one semi-closed hood and roof cover. △ semi-closed cover The semi-closed is composed of fixed cover and movable cover, the movable cover can remove to the top of transformer. Semi-closed cover is widely used in dust removal system of medium and small electric furnaces in recent years. Compared with roof cover, the advantages are: the system drafting amount is smaller, flue gas collection efficiency is higher, investment and operating costs are relatively low. Semi-closed cover can completely capture the flue gas during furnace smelting, however, its capturing efficiency of flue gas produced material loading and unloading is not satisfied and opening, closing of the semi-closed cover has certain impact for the smelting period. △Diversion roof cover The diversion roof cover is composed of diversion cover and roof cover. The diversion cover is composed of fixed cover and movable cover, the former is installed at material unloading side and at the back of furnace, while the latter is installed at the top of transformer behind furnace. The movable diversion cover will be moved to the top of transform during material feeding and be moved out of furnace proper during smelting. The fixed and movable diversion covers surround electric furnace, forcing the flue gas arising within the diversion cover area. After flue gas rises to the diversion cover hole, the distance between gas and cover is only 5m, which minimize the bad effect of transverse flue gas. After commissioning, the movable cover can be fixed and only be moved during maintenance so as to decrease operation procedures. The roof cover is inner and outer double layers structure. The inner cover will collect the flue gas flowed out from diversion cover along diffusion corner, while the outer cover will collect the overflowed flue gas. The diversion roof cover can remove flue gas produced in smelting, which is environmental friendly and easy to be operated, but the disadvantages are that air discharging amount is large and investment, operation cost is high. flue gas collection technology of LF furnace