| 摘要 |
<p>The invention is both an equipment and a process for preheating up to 800 TO 1000°C, of the scrap, either baled or loose steel scrap and sponge iron/ DRI without the danger of re-oxidation of the charge, required for manufacturing Steel, and mechanized charging of the same into the Induction Furnace crucible, which reduces specific power consumption (KWH/ Tonne) by about 250 KWH/ Tonne of material charged, amounting to approximately 35% of hitherto consumed Electrical power for Melting, and also increases the production by 30 - 40% due to shorter melting time in the crucible. Additionally this reduces EOT Crane requirement time for charging the raw materials into the crucible, as most of the handling is taken care of by the PEO. The invention allows for automation of the feed rate of the charge and reduces manual labour. The invention reduces the level of Carbon Emissions considerably, especially when biogas is used as alternate fuel for heating in the combustion chamber. The invented equipment is the mechanical means of moving the charge from the cold end at the top hopper to the hot end and into the crucible at the desired and pre-set rate and quantity. The mechanical means consists of one of the following: 1. Bucket, (as per Fig. I) for heating non baleable steel scrap, 2. Vibratory Trays and /or Slat conveyors, Fig II for Sponge Iron, steel bales, shredded scrap, pig iron etc. The invented process is the step taken during the heating to prevent re-oxidation of the charge from iron back to iron oxide and prevention of conglomeration of the charge into an inseparable mass as experienced hitherto. Equipment: The heater consists of a combustion chamber which generates hot flue gases at above 1200°C. A system of vibrating trays/ or slat conveyors each of 8m or greater length with suitable inclinations, is mounted in multi storeyed fashion over the combustion chamber. The flue gases pass over the sponge iron vibrating on the trays heating it to the required temperature. The rate of flow of the sponge iron is adjusted by varying the speed of the vibrators through variable frequency drives (VFD) or adjusting the speed of the slat conveyors. The fuel used can be any one of furnace oil, pulverized coal, Compressed Natural Gas, bio gas etc. If biogas is used there would be a substantial drop in CO2 emissions. The final portion of the PEO ends in a vibratory Steel pipe, with refractory coated inside and the last 4m outside coated as well. The Sponge Iron is deposited either on the crucible rim or inside the crucible near the walls or centrally as desired by the Melter. The system is so designed as to capture maximum heat from the exiting gases from the crucible. The incoming air for the combustion air blowers is also preheated using the waste heat of the flue gases exiting the PEO. By proper combustion and maintenance of air-fuel ratio, excess air is avoided in the flue gas which would be sufficient to prevent re-oxidation of the scrap/ sponge iron.</p> |
