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Wednesday, March 18, 2015

#208 - Tenova Core Receives Order from Bilstein Group for Bell-Type Furnaces

Tenova Core has been contracted by Bilstein Cold Rolled Steel LP for the design and supply of HPH (high-performance hydrogen) bell-type furnaces for installation at its facility in Bowling Green, Ky. The furnaces will be used to anneal steel strip coils in a 100% hydrogen atmosphere. The project scope includes: HPH heating hoods, annealing bases and JET cooling hoods as well as associated equipment and process-control systems. 
A special high-performance recirculation system ensures effective gas circulation and superior temperature uniformity. The annealing-base design is optimized for obtaining the lowest dew point possible and can be used for annealing almost any grade of steel strip coil. It also provides many years of dependable operation while requiring minimal maintenance. JET cooling requires no cooling water and ensures homogeneous cooling of all coils.

A bell furnace is a batch-operated heat-treatment furnace in which products are heated under a movable dome. It is used for heat treatment of sheet and light-section rolled products in a controlled gaseous medium. Tenova’s HPH system uses hydrogen as the atmosphere gas and features high-convection technology. The advantages of hydrogen compared with nitrogen include lower density, higher thermal conductivity and improved reduction potential, resulting in enhanced strip cleanliness. As a result, this technology has established itself as a standard throughout the world.

Bell furnaces are classified according to use (treatment of coils of narrow strip, sheets, rods, and so on). The most common bell furnaces are the single-stack and multistack types used for annealing coils of cold-rolled steel strip. In multistack bell furnaces, three to eight stacks, each of which has its own muffle for protection against the effects of the hot air and products of combustion, are mounted on a rectangular stand under the heating dome. Each stack is 3–5 m high and contains three to five coils with a total weight of up to 180 tons.

The bell furnace dome is heated by gas or electrical resistance heaters. Upon completion of the heating process, the dome is transferred by crane to another stand and the products are left to cool under the muffles on the first stand. Heat exchange under the muffle is intensified by forced circulation of controlled gas. Cooling is accelerated by wetting the muffle with water or blowing cold air over it.

During treatment in a bell furnace the coils of strip are loose, with spaces between the coil loops so that the gas circulates between the loops and flows over the entire surface of the strip, which makes possible thermochemical treatment and acceleration of heating and cooling.

For more information, contact Tenova Core at:

Tenova Core
Cherrington Corporate Center
100 Corporate Center Drive
Coraopolis, PA 15108-3185
Phone: (412) 262-2240
Fax: (412) 262-2055

Plant photo of bell furnaces from Tenova Core.
Bell furnace diagram from Industrial Heating article The Annealing Process Revealed (Part Three: Annealing of Steel Coils) Some information from Tenova Core website and from The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


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