Industrial electric heating furnaces – Arc furnace device – Furnace body detail
Reexamination Certificate
2000-05-24
2001-02-06
Hoang, Tu Ba (Department: 3742)
Industrial electric heating furnaces
Arc furnace device
Furnace body detail
C373S072000
Reexamination Certificate
active
06185242
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a spray cooled system for the side wall and tap hole cover of an eccentric bottom tap (EBT) electric furnace, e.g. an electric arc furnace having a generally circular hearth portion, below one or more electrodes, in which steel scrap is melted, and an adjacent eccentrically configured relatively shallow portion which has a valved, bottom tap-hole through which molten steel can exit the furnace upon opening of the valve and tilting of the furnace.
The most common configuration of an EBT furnace comprises a main, “tall” section, which is spray or water-cooled, and positioned above the circular portion of the fiurnace and, an adjacent lower EBT (eccentric) extension that includes the “sand hole” through which sand is poured to cover and protect the tap hole valve of the fuxnace. The “tall” section is provided with a removable, circular water-cooled or spray cooled roof and scrap metal is charged to the furnace and melted beneath the roof. Upon completion of melting the entire furnace is tilted toward the eccentric (tap) portion with the tap valve is open to allow molten steel to be discharged from the furnace into a ladle positioned below the furnace. When tapping is completed, the taphole valve is closed and the furnace is leveled. Sand is then poured through the sand hole in the cover and into the tap-hole in the refractory hearth below to protect the underlying tap-hole valve. The furnace is then ready for melting and tapping the next charge.
The cover for the EBT (eccentric) portion is customarily a pressurized water-cooled panel or a separate spray cooled panel. The water-cooled panel is usually flat and horizontal and includes a sand hole. The separate spray cooled panel is a combination of a sloping plate and a conical portion which allows effective flow of water onto and off the plate. The spray-cooled panel also contains a sand hole and has a spray cooled chamber. In use, the separate spray cooled panel is bolted to the “tall” spray cooled section with each section having it's own coolant supply and independent drains for spent coolant. This type of spray cooled configuration is subject to fume and flame discharge at the joint between the main “tall” section and the EBT cover, and spent coolant can not equalize between the sections.
Another prior commercial arrangement included an egg-shaped roof which covered both the circular and EBT portions of the furnace which resulted in a single, very heavy “tall” section with the sand-hole located in the roof, high above the tap-hole which complicates filling of the tap-hole.
SUMMARY OF THE INVENTION
In accordance with the present invention, a spray cooled, hollow side wall is provided for the circular portion of an EBT furnace and a hollow EBT cover portion is integrally attached to the side wall, e.g. by welding to provide a unitary, i.e. one piece side-wall and tap-hole cover. The EBT cover portion is attached at a lateral mid-section of the side-wall and is vertically extending but to a much lesser extent than the side-wall, e.g. about ¼ to ⅓ the height of the side wall. The EBT cover portion is hollow and has an upper cover and a lower arched plate; the lower arched plate is spray cooled by nozzles within the EBT cover. The nozzles receive coolant, e.g. water, from a conduit which is connected to the water conduit in the spray cooled side-wall, and spent coolant can drain from the EBT cover to the side-wall, and, when the furnace is tilted, from the side-wall to the EBT cover. The lower plate of the EBT cover is shaped to conformally contact the inner spray cooled wall of the side-wall and this conformal contact is shielded by a metal strip which is welded to the inner wall of the side-wall and the lower plate and the weld area and metal strip are easily cooled by coolant from nozzles in the EBT cover.
REFERENCES:
patent: 3952140 (1976-04-01), Wunsche
patent: 4715042 (1987-12-01), Heggert
patent: 4813055 (1989-03-01), Heggert
patent: 4815096 (1989-03-01), Burwell
patent: 4849987 (1989-07-01), Miner
patent: 5115184 (1992-05-01), Arthur et al.
patent: 5290016 (1994-03-01), Elsner
patent: 5327453 (1994-07-01), Arthur
patent: 5330161 (1994-07-01), Lehr
patent: 5444734 (1995-08-01), Arthur
patent: 5561685 (1996-10-01), Lehr et al.
patent: 5648981 (1997-07-01), Miner
patent: 5936995 (1999-10-01), Sullivan et al.
patent: 1220503 (1987-04-01), None
Arthur Mark Thomas
Miner Frank Henry
Roberts Gordon Raymond
Hoang Tu Ba
McCarthy Frederick J.
South Carolina Systems, Inc.
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