| 摘要 |
<p>PURPOSE: To achieve a high heat exchange rate and hence greatly improve high preheating efficiency while avoiding melting of iron scrap by limiting scrap temperature at a lower part in a second preheating furnace to a specific value and thereafter supplying the scrap to the next preheating furnace, and preheating the scrap using high temperature waste gas from a melting furnace. CONSTITUTION: One end of a first preheating furnace 2 of a rotary kiln type first preheating furnace 2 rotatably inclined around a cylindrical shaft is connected with an upper part of a melting furnace 1, and a lower part of a shaft furnace type second preheating furnace 3 extending longitudinally at a predetermined height is connected with the other end of the first preheating furnace 2. Iron scrap is inserted into from an upper part of the second preheating furnace 3, and waste gas that passes through the first preheating furnace 2 and the second preheating furnace 3 from the melting furnace 1 is exhausted from an upper part of the second preheating furnace 3. Scrap charged from the upper part of the second preheating furnace 3 is preheated in the preheating furnace 3, and is thereafter fed to the first preheating furnace 2 for again preheating. Here, scrap temperature at a lower part of the second preheating furnace 3 is restricted to 800 deg.C or lower.</p> |
