RECENT ASSIGNMENT

Reheat Furnace Operations in a Steel Mill:
The reheat furnace or slab furnace is basically a large heated, refractory lined chamber, through which the slabs advance at a control rate, reaching the discharge end of the furnace at rolling temperature. At the charge end, slabs are loaded by overhead crane onto the walking beam change table, which advances the slabs to the furnace beams. At the discharge end, a slab extractor will remove the slabs from furnace and deposit them on the rolling mill tables to be made into other products such as oil, gas or water pipelines, etc…
The furnace dimensions and capacity are as follows:
• Furnace chamber: 105 ft long by 33 ft wide
• Design capacity: 175 tonnes per hr
• Slabs size: 10 in x 40 in x 30 ft
• Slabs to be heated from -40 F to 2400 F in the winter and 100 F to 2400 F in the summer.
Perform the following calculations:
• Determine the time require for the winter heating
• Determine the time require for the summer heating • Calculate how much energy saving between the two
• Report:
o Show the detailed steps of the calculations o Plot the temperature profiles at the surface and the center vs time
• Assumptions:
o The furnace temperature is constant at 2500F o The slabs are made of mild steel