Scale Formation in Reheating Furnace May25

Scale Formation in Reheating Furnace...

Scale Formation in Reheating Furnace  Reheating furnaces constitute an important element in the rolling of steels, in which the semi-finished steel products are heated to a desired temperature for achieving the plastic properties in the products for rolling. The basic purposes of heating the semi-finished steel products for rolling include (i) to soften the steel for making it suitable for rolling, and (ii) to provide a sufficiently high initial temperature so that rolling process is completed in fully austenitic temperature region. During reheating in the reheating furnace, steel is passed through the furnace along which the temperature is gradually increased up to the soak zone. In there, the temperature is kept constant for thermal and chemical homogeneity of the steel. The reheating furnace is a direct fired furnace which uses either of the gaseous, liquid, or solid fuel and air. The composition of the atmosphere within the furnace generally consists mainly of nitrogen (N2), Carbon di-oxide (CO2), water vapour (H2O) and free oxygen (O2). The atmosphere composition can vary drastically during the operation. These variations are functions of the air/fuel ratio, which in turn, depends on furnace and mill operating conditions. Reheating furnace for the reheating of steel is conceptually divided into three zones. Starting from the discharge end of the reheating furnace, these zones are (i) soaking zone, (ii) heating zone/zones, and (iii) pre-heating zone. In the soaking zone, fuel and air is fired through the furnace burners at normal or reduced primary fuel stoichiometry. This zone has high furnace temperature. The temperature of steel is equalized through its cross section in this zone. The exhaust gases from this zone travel to heating zones. The heating zones, which are between preheating zone and the soaking zone, require high radiant heat transfer for increasing...

Romelt Process for Ironmaking Mar20

Romelt Process for Ironmaking...

Romelt Process for Ironmaking Romelt process for ironmaking is a smelting reduction process for the production of hot metal (liquid iron). The process has been developed by The National University of Science & Technology ‘MISiS’, Russia (formerly known as Moscow Institute of Steel and Alloys). The development work of the process started in 1978 when a group of ‘MISiS’ scientists led by Vladimir Roments began working on designing of this process. The first patent in Russia was obtained in 1979. A pilot production plant having a hearth area of 20 sq m and with a capacity 40,000 tons of hot metal per year was commissioned in 1985 at the Novolipetsk Iron and Steel Works (NLMK). The pilot plant was designed by Moscow Gipromez. The design of the reliable Vanyukov’s furnace was taken as the prototype for this new method of manufacturing hot metal. The process was tested and mastered at this pilot plant between 1985 and 1998. During this period forty-one campaigns were carried out, each of which included startup and slowdown, with full tapping of hot metal and slag from the furnace. More than 40,000 tons of hot metal was produced in the pilot plant during this period and used further in basic oxygen furnace (BOF) for steelmaking. The first industrial plant for hot metal production based on Romelt technology is being built at Myanmar. The plant has been designed by Leningrad Gipromez and being supplied by Tyazpromexport, a subsidiary of Rostec. This plant has a capacity of 200,000 tons per year and is based on the processing of iron ore without its beneficiation from Pang Pet ore deposit. Pang Pet ore deposits have Fe content of up to 29 %. The plant will use non-coking coal from Kye Thee coal fields. The...