The Electric Arc Furnace Shell as a Metallurgical Vessel
The Electric Arc Furnace (EAF) shell serves as the core containment vessel for the metallurgical smelting process. During operation, the intense heat and corrosive action of molten steel and slag progressively degrade the refractory lining within the lower furnace shell. Consequently, this lower section typically requires a complete replacement (or "lift-out") every 300 to 400 heats. This major maintenance task, along with other routine work, necessitates the lifting and handling of other major components, namely the furnace roof (cover) and the upper furnace shell.
Currently, the handling of these large components for high-capacity EAFs involves different methods and dedicated lifting attachments. The furnace roof and upper shell are usually hoisted by a single crane employing wire rope slings.
Traditional Methods for Lifting the Lower Furnace Shell:
The lifting of the heavier and more cumbersome lower furnace shell has historically been accomplished through several methods:
These methods present significant drawbacks:
Methods 1 & 3: The direct contact of wire ropes can cause squeezing and abrasion damage to the top edge of the lower shell. Furthermore, force distribution is often unbalanced, leading to unstable lifting, difficulty in precise positioning, and potential safety hazards.
Methods 1 & 2 (using two cranes): Require precise synchronization between two cranes, which is difficult to achieve, often resulting in an unbalanced lift. This approach also complicates production scheduling, increases labor intensity, and extends operational downtime.
Methods 2 & 4 (using dedicated spreaders): While offering better control, they necessitate a dedicated storage stand for the special spreader when not in use, adding to capital investment and consuming valuable floor space in the workshop.
In summary, prior art solutions require maintaining three separate sets of lifting gear (slings, beams, spreaders) in reserve to handle the roof, upper shell, and lower shell. This not only increases capital expenditure and occupies limited workshop area but also complicates equipment management. The additional need for a storage rack for a dedicated lower-shell spreader further adds to the cost.
Addressing the Technical Challenge:
To solve these problems—specifically, the inconvenient and costly lifting/transportation of EAF components—a novel solution has been developed: a Dual-Hook, Three-in-One Spreader. This integrated device is designed to handle the furnace roof, upper shell, and lower shell with a single attachment system.
Technical Solution Overview:
The utility model comprises a rectangular box-frame structure. The upper surfaces of the front and rear horizontal members of this frame are symmetrically fitted with off-center lifting lugs. These lugs are positioned based on a comprehensive calculation of the combined center of gravity for the specific component being lifted and the spreader itself.
Key design features on the sides of the frame facilitate secure attachment to different furnace parts:
The left side incorporates protruding first horizontal sections at its upper and lower parts.
The right side features sequentially connected second horizontal and third bent sections at corresponding heights.
Advantages of the Three-in-One Spreader:
