Apparatus and process system for preheating of steel scrap for melting metallurgical furnaces with concurrent flow of scrap and heating gases

摘要

The invention relates to a novel preheating device and a method for preheating an iron scrap mixture before delivering the scrap iron into a metallurgical furnace. The invention primarily makes use of heat which is recovered from hot waste gasses that have been emitted from the furnace outlet. The invention is also provided for simultaneously reducing contaminated substances from the scrap iron and from the waste gasses with a downward stream comprised of the hot waste gas and of the downward falling scrap iron which flow in the same direction. The invention has a chamber comprising an upper compartment having a cold scrap iron feed provided for dumping cold scrap iron into the upper compartment and a hot gas inlet which is flow-connected to the furnace outlet. The chamber also has a lower compartment with an unloading mechanism for the heated scrap iron in order to forcibly deliver the heated scrap iron into the furnace and has a waste gas outlet which is flow-connected to a vacuum outlet and provided for evacuating the used waste gas. Gates which allow gas to pass through are arranged between each chamber compartment and sequentially operate between a closed gate position and an open gate position for receiving a scrap iron charge which is delivered in a closed gate position from the cold scrap iron feed in the same direction by means of gravity. During a predetermined hold period, the scrap iron charge is stored while hot waste gas flows downward out of the hot gas inlet in the upper compartment, penetrates through the scrap iron charge and through the closed gate, and flows out of the waste gas outlet in the lower compartment. The gates mix the scrap iron when it falls and serve to control the gravitational downward movement of the scrap iron charge from the upper compartment to the lower compartment after the hold period has elapsed.