CHARGING BOX FOR AN OPEN HEARTH FURNACE
United States Patent 3618795
A box for charging scrap into an open-hearth furnace has a longitudinal triangular groove in its bottom with flat portions on each side. In charging the furnace scrap is placed in a plurality of these boxes which are placed on a charging car having a plurality of spaced apart transverse triangular projections. Each box is positioned with its groove fitting over one of the projections. The scrap is then charged in the usual way. Other additives, such as iron ore and limestone, are placed in smaller boxes having a width such that the boxes can be held in position on the car between adjacent triangular projections. The small boxes so positioned are unloaded into the furnace in the usual way.
F27D3/00; (IPC1-7): F27D3/06; F27D3/12
Field of Search:
Sheridan, Robert G.
1. A charging box for an open hearth furnace comprising spaced-apart sidewalls, end walls connecting the sidewalls, a peel socket on the outside of one end wall, and a bottom wall connecting the bottoms of said side and end walls, said bottom wall having a single large longitudinal triangular projection extending upwardly into said box at the center thereof and flat portions on each side thereof, said projection having a wall thickness substantially the same as the remainder of said bottom wall so as to provide a large longitudinal open triangular groove in said bottom wall, the height of said triangular groove being between approximately 10 and 15 percent of the total height of the box.
2. A charging box according to claim 1 in which said triangular groove has a width between approximately 25 and 35 percent of the total width of the bottom wall.
3. A charging box according to claim 1 in which the apex angle of said triangular groove is between 80° and 100°.
4. A charging box according to claim 1 in which the apex angle of said triangular groove is approximately 90°.
This invention relates to apparatus for charging open hearth furnaces and particularly to that part of the charging in which solids are charged. In the usual method of charging open hearth furnaces steel scrap is placed in charging boxes mounted on a charging car and delivered to the front of the furnace. A charging machine running on tracks parallel to the line of the furnaces is equipped with a ramlike peel mounted on a trolley. The charging box has a peel socket on the outside of one end wall which is engaged by the peel. When so engaged the charging box is raised from the charging car and the trolley is moved forward to insert the box through the door opening into the furnace. The peel is rotated to turn the box upside down to dump the scrap into the furnace after which the peel and box are withdrawn and the box placed on the charging car after which the charging car or a string of charging cars are moved by the charging machine engaging the side of a charging box to position another filled car in front of the door opening. This charging operation requires about 1 minute to charge each box and it takes approximately 45 minutes to charge all the necessary scrap into the furnace. A common type of charging car has transverse triangular projections spaced apart longitudinally of the car in such a way that the charging box rests between adjacent projections.
In addition to the loading of scrap, other solid additions including iron ore and limestone are added. However, the volume of such additions is relatively small and the time consumed in charging these additions is negligible. In many plants the equipment available for loading iron ore and limestone is such that the present size of the charging boxes cannot be exceeded. Thus, while substantial savings in time could be accomplished by the use of larger charging boxes for scrap this cannot be done by merely increasing the size of the present type of charging box.
It is therefore an object of my invention to provide a new type of charging box that can be made in a larger size than the present type charging box and yet be used in conjunction with the present charging cars.
This and other objects will be more apparent after referring to the following specification and attached drawing, in which:
FIG. 1 is a schematic view of an open hearth furnace and charging equipment;
FIG. 2 is a view of a charging car with charging boxes shown thereon;
FIG. 3 is a top plan view of the charging box of my invention;
FIG. 4 is a view taken on the line IV--IV of FIG. 3; and
FIG. 5 is a view taken on the line V-V of FIG. 4.
Referring more particularly to the drawings, reference numeral 2 indicates a steel making open hearth furnace having door openings 4 therein. While only one such door opening is shown it will be understood that more than one such door is usually provided in such furnaces. Charging cars 6 are mounted on tracks 8 which run in front of the furnace parallel to the front thereof. A charging machine 10 is mounted on tracks 12 parallel to tracks 8 and includes a trolley 14 which carries a peel 16. The charging cars 6 are provided with a plurality of spaced-apart transverse triangular projections 22. The projections 22 are so spaced as to receive a relatively small size conventional charging box 24 therebetween as shown in dash-dot lines in FIG. 2. The box 24 is provided with a conventional peel socket (not shown). The parts so far described are conventional.
According to my invention I provide a larger size charging box 28 which has sidewalls 30 connected by end walls 32. One of the end walls is provided with a standard peel socket 34 of the same size and type as on the charging box 24. The bottom of walls 30 and 32 are connected by a bottom wall 36 of substantially uniform thickness. The bottom wall includes a large longitudinal triangular projection 38 on each side of which are flat portions 40. The projection has a wall thickness substantially the same as that of portions 40 so as to provide a large longitudinal triangular groove 42 in the bottom wall. The width of the triangular groove is between approximately 25 and 35 percent of the total width of the bottom wall and its height between approximately 10 and 15 percent of the total height of the box. Apex angle 44 of the groove 42 is preferably 90° but may be between 80° and 100°, this angle being best to guide the box 28 over the projection 22 and at the same time providing the sidewalls of the groove with sufficient steepness to prevent the box from sliding out of the groove when the side of the box is engaged by the bridge 14 to move the car from one position to another. If the height of the groove is much less than 10 percent of the total height of the box it will not provide sufficient bearing surface to hold the box in position when pressure is applied thereto. On the other hand, if the height exceeds 15 percent too much of the interior volume of the box is eliminated to obtain best results.
In operation, when it is desired to charge scrap into the furnace, a plurality of filled charging boxes 28 are placed on the charging car 6 with a triangular projection 22 being received in each groove 42 as shown in FIG. 2. Charging of the furnace then proceeds in the usual manner. With a box 28 in front of door opening 4, the operator positions peel 16 in the peel socket 34, then raises the box from the car and feeds it through the door opening 4 into the furnace as shown in dash-dot lines in FIG. 1. The peel is rotated to turn the box 28 upside down and dump the scrap into the furnace. The empty box is then placed in position on the car 6 and the car moved along until the next box is positioned in front of the door opening. This operation continues until the entire scrap charge is positioned within the furnace, it being understood that the scrap will be introduced through more than one door opening in the usual manner. When iron ore, limestone and/or other solid additives are to be introduced into the furnace the smaller size boxes 24 are positioned on the car 20 between adjacent projections 22. With the additives in the boxes in front of the furnace the additives are charged into the furnace in the same manner as the scrap.
While one embodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made.