Furnace rider bar assembly

Details Furnace rider bar assembly Furnace rider bar assembly

1997-10-28

1999-04-27

Walberg, Teresa

Heating

Heating apparatus element having protective cooling structure

Work skid or rail structure

432127, F27D 302

Patent

active

058973109

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to an improved product support system for a walking beam re-heat furnace.


BACKGROUND OF THE INVENTION

Steel product, such as slabs, blooms, bar stock and semi-furnished products are re-heated prior to hot working to produce hot rolled steel products. One conventional form of furnace used for such re-heating has been a low output top-fired furnace in which product to be heated sit on a refractory hearth; with the product conveyed through the furnace by pushers. Such furnaces have been improved to achieve higher outputs, by utilising top and bottom firing to reduce the time required for conduction of heat energy in the product to achieve a uniform temperature throughout the product.
A more recent development is the so-called walking beam furnace. This offers several advantages over the pusher furnace. The present invention principally is concerned with improvements applicable to the walking beam furnace. However, the invention can be used in at least some forms of pusher furnaces.
One benefit of the walking beam furnace is that it is self-conveying. This is achieved by having several fixed beams, extending through the furnace from the front or inlet to its exit, and several moving beams substantially parallel to the fixed beams. Product to be re-heated is supported on the fixed beams at successive locations along their length. The moving beams are actuated by hydraulic cylinders located under the heating chamber of the furnace, so as to be movable from, and back to, a lowered or ambush position so as to lift and index product forward, as required, from one to a next position on the fixed beams.
There was a major advance in walking beam furnaces in the mid-1960's when the Surface Combustion Co. of the United States of America developed a top- and bottom-fired furnace with moving beams comprising water-cooled lifting rails. This provided for supporting product alternately, and for substantially equal intervals, on the moving and stationary beams of the walking beam conveyor system. Also, by suitable design of support structure of the beams, it was possible to heat thick product slabs without the need for a soaking refractory hearth. Such hearth was used in pusher furnaces, and in early forms of walking beam furnaces, to enable regions of the lower surface of the product, cooled by contact with the support structure, to attain overall temperature uniformity throughout the product.
Over the last thirty (30) years, almost all new re-heating furnaces have been of the walking beam type. It is believed that about 50% of all furnaces for re-heating steel product are of that type, with about two hundred (200) such furnaces currently in operation throughout the world.
In the fixed and moving beams of the furnace based on the Surface Combustion Co. furnace, and in developments thereof, the water-cooled lifting rails comprising the beams have rider or skid bars mounted thereon. While designated as bars, the rider or skid bars can be of a variety of forms. Those based on the 1960's developments are in the form of buttons or cylinders about 75 mm high, 50 mm in diameter and located at about 300 mm spacing along the beam. However, other forms of rider bars in use are more rectangular in plan view, such as about 35 mm transversely, and about 140 mm longitudinally, of the beam and at a closer pitch interval so as to more closely resemble continuous rider bars. Usually, the rider bars are detachably mounted on their water-cooled pipes. This form of mounting may, for example, be by steel keeper plates which are welded to the pipe, and which are able to be ground off when replacement of rider bars is required.
The water-cooling of the pipes comprising the fixed and moving beams have a large cooling effect in the lower region of the furnace chamber. To reduce this, the cooled beams are insulated by shaped refractory insulation which encloses the beams except along the line of its rider bars. However, the insulation shields the bottom surface of the product from heating burner flam

REFERENCES:
patent: 3985496 (1976-10-01), Eickelberg
patent: 4368038 (1983-01-01), Bourdon et al.
patent: 4689009 (1987-08-01), Heuss
patent: 4747775 (1988-05-01), Takagi et al.
patent: 5136610 (1992-08-01), Heuss
patent: 5271610 (1993-12-01), Klotz
patent: 5284440 (1994-02-01), Campbell, Jr. et al.
patent: 5288228 (1994-02-01), Fujita et al.

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