US2119424A - Method of charging furnaces - Google Patents

Description

May 317 P. H. OUGLAS ET AL METHOD OF CHARGING FURNACES Filed June 21, 1935 6 Sheets-Sheet 1 cia , INVENTORE! 3404- hi DOUGLAS BY JOHN IL.- [90 5 Mn am ATTORNEYJ May 31, 1938. P. H. DOUGLAS ET AL METHOD OF CHARGING FURNACES 6 Sheets-Shet 2 Filed June 21', 1935 INVENTORS. P404 hf Oaaeurs Jaw/v 5 906519? ATTORNEYS May 31, 1938. P. H. DOUGLAS El Al."

METHOD 0? CHARGING FURNACES 6 Sheets-Sheet 3 Filed June 21, 1935 INVENTORE. PAUL H DOUGLAS BY JaH/v E ROGERS ATTORNEY 6 Sheets$heet 4 e 9 a W MW 2 A w m r m llvm llllml EH N .QLWAIW Atflllfilll N V I LK A F ATTORNEYDY May 31, 1938. v P. H. DOUGLAS ET AL METHOD OF CHARGING FURNACES Filed June 21, 1935 y 1938. P. H. DOUGLAS ET AL 2,119,424

METHOD OF CHARGING FURNACES Filed June 21, 1935 6 Sheets-Sheet 5 Fig, 72 I INVENTORE,

B404 hf 0006448 BY Jon/v F. /-?o Gems flag, Mn M ATTORNEY? May 31, 1938. P. H. DOUGLAS ET AL METHOD OF CHARGING FURNACES 5 sheets-sheet 6 Filed June 21, 1935 S E? v t w m m m a G W o 0 MN )lfl" I I 0 H A E m N A M P J afmz ATTORNEYE Patented May 31, 1938 PATENT OFFICE METHOD OF CHARGING FURNACES Paul H. Douglas and John F. Rogers, Cleveland Heights, Ohio, assignors to The Wellman Engineering Company, Cleveland, Ohio, a corporation of Ohio Application June 21, 1935, Serial No, 27,779

4 Claims.

This invention relates to a process of, charging furnaces, and it has special reference to the charging of open hearth furnaces with cold metal which, as is well known, consists generally of 5 scrap and at times of a mixture of scrap and pig iron.

The type of cold metal charging machine usually employed in steel works, either as the machine was originally built many years ago or later improved and modified, is in general essentially the same. It comprises a rectangular carriage which is fitted at each end with wheel trucks enabling the carriage to travel on a runway which is either elevated or is on the level of the chargingfloor and is installed parallel to the face of the furnaces a series of which are usually arranged in a line. This carriage is equipped with a traveling trolley which moves crosswise of the runway on top of the carriage to and from the furnace.

This trolley is equipped with a charging ram which is adapted to engage one at a time cold metal filled boxes which are brought in position between the front of the furnace and the'charging ram and are inserted into the furnace through the conventional type of furnace door. After insertion, each box is overturned to dump its contents in the interior of the furnace, after which the ram is withdrawn, the empty container is disposed of, and the machine proceeds to complete the cold metal charge by successive operations, as above described. a

From the above it is apparent that the rate of charge is determined by the size of the cold metal box and to a certain extent the capacity of the box ram is limited by the structural strength of its necessarily long slender body. Considering the size of the modern open hearth furnace and the amount of cold metal of which the charge is composed, it will be obvious that to completely charge a furnace with cold metal the charging machine is required to be put through a large number of charging cycles, with the result that considerable time is expended in charging the furnace and the frequent opening of the furnace doors for the insertion of the ram and the charging box causes large heat losses calling for a considerable consumption of fuel over that required for actual metal melting. Furthermore, the continuousrepetition of the numerous motions which comprise each of the charging cycles consumes, by reason of necessarily short periods of run, an amount of power altogether out of proportion to the metal hair'- dled, and the cost of machine maintenance is unduly high due to the very frequent rapid acceleration and the sudden stoppage of power driven mechanisms involved in a machine of this nature.

Furthermore, in view of the fact that the charging box is of necessity rather small by reason of the limitations in size imposed by the structural characteristics of the charging ma-- chine and particularly the ram, and also by the size of the'furnace doors a number of which are provided at the front of each furnace, it is necessary that the scrap which constitutes the sole or the major portion'of the cold metal charge be cut or otherwise reduced to small size. Otherwise, due to irregularities in the lengths and shapes of the scrap, difliculty would be encountered infilling the charging box at least with any considerable amount of metal.

It is the chief object of the present invention to depart from the spoonf method of cold metal charging and to handle the cold metal. charges in large bulk comparable with the methods and machinery for handling practically all other products in steel works.

Q Further, the invention aims to provide a charging process which permits a large part and preferably the entire cold metal charge required for the melting heat to be deposited in the furnace at one time, thereby affording a more economical process as to power and fuel consumption, speed of operation, and maintenance cost of the charging equipment and furnace.

More specifically considered, it is the aim of the present invention to provide an entirely novel cold metal charging process which eliminates the use of the present small charging box with its transporting apparatus and the present type of charging machine and which utilizes instead a container of ample capacity to handle, if desired, the entire cold metal charge and a charging machine of simple design and few motions which, with certain modifications in the structure at the front of the furnace, and the provision of an appropriately large door or removable furnace front, enables the cold metal charge to be deposited preferably in one charging operation over the entire furnace hearth by progressively depositing it thereon in a layer of approximately uniform thickness.

The above and other objects are attained by the present invention which may be briefly summarized as consisting in the novel steps of the charging method which will be described in the specification and set forth in the appended claims.

' In the accompanying sheets of drawings wherein the various steps of the charging process are illustrated with the equipment shown more or less diagrammatically or conventionally;

Fig. 1 shows the charging container 'for the cold metal which will be assumed to be scrap, this container being preferably in the form of a pan with a movable flexible bottom, the filled container here shown being on a yard car running on a track at the yard level and about to be hoisted to the charging floor level on which Fig. 6 is a similar view with the charging operation partly completed;

Fig. 7 is a. similar view at the completion of the charging operation with the cold metal deposited on the furnace hearth;

Fig. 8 is a similar view with the carriage and pan fully retracted from the furnace and with the furnace front restored ready for the melting operation;

Fig. 9 is a plan view of the charging machine with the loaded pan in position in front of the furnace. which is shown in horizontal section,

this view corresponding to or showing the parts in the relative positions of Fig. 4;

Fig. 10 is a similar view corresponding to Fig. 5; Fig, 11 is a similar view corresponding to Fig. 6; Fig. 12 is a similar view corresponding to Fig. 7-; Fig. 13 is a similar view corresponding to Fig. 8;

Fig. 14 is a longitudinal vertical sectional view of the pan or container on a slightly enlarged scale; and

Fig. 15 is a vertical sectional view of the pan on a still larger scale with parts broken away to more clearly show the flexible bottom which is here shown partly rolled back under the cradle to illustrate the manner in which the bottom drops away from beneath the cold metal charge as the cradle and the pan body move backward in the charging operation.

In applying our invention to the charging of open hearth furnaces for which it is especially adapted, there is required not only a radically different and novel charging machine and container for the scrap or other cold metal, but also a reconstruction of the front of the furnace and a new way of opening the furnace for the inser-- tion of the forward end of the charging machine, the pan or container, and the cold metal.

Heretofore, the front of the furnace was equipped with a series of relatively small doors which were individually removed for the insertion of a filled charging box. However, with the improved method of charging here involved, a relatively wide opening is required the width of which depends upon whether the entire cold metal charge is supplied to the furnace at one time and distributed over the entire hearth in one charging operation or whether the charging is to be accomplished in more than one charging operation. If the entire cold metal charge required for the melting heat is deposited over the hearth in one charging operation, as is preferred, a door opening is required which is equal in width to substantially the length of the hearth, and to take care of .such a wide opening we propose to provide the furnace with a single wide door or removable furnace front which extends substantially'the length of the furnace hearth to close the relatively wide door opening referred to. This door or, perhaps more properly speaking, this furnace front is designed to be lifted and moved forwardly from the door opening and then elevated so as to be out of the way of the charging machine and to permit the charging operation to-be performed as hereinafter described and subsequently to be restored in place to'close the front of the furnace. This furnace front may be provided with a series of spaced independently removable doors comparable with those now employed at the front of an open hearth furnace so as to permit charging with hot metal and for repairs to the furnace lining.

If in some instances it is desirable to charge the furnace in two or more charging operations, door openings of less width may be employed and a cold metal container of a width equal substantially to the part of the hearth which is to be covered with cold metal in one charging operation maybe utilized. As the supplying of the entire cold metal charge in one operation is preferred, a cold metal container and a charging machine having a width equal substantially to the length of the hearth and a removable furnace front or door equal also substantially to the length of the hearth so as to accommodate the wide cold metal container and charging machine are herein illustrated.

Referring now to the drawings, we have indicated at 20 an open'hearth furnace of standard size which means that in a commonly employed 150 ton furnace the hearth 20a over which the cold metal is uniformly deposited by the charging machine will be approximately 45 feet in length. "The capacity and length of hearth is mentioned not in any limiting sense but to better emphasize the capabilities of the charging equipment and the radical departure from time honored standard practices in the charging process. The furnace may be of usual or standard construction except for the provision of a very long opening at the front forthe insertion of the charging machine and the cold metal filled container and except forthe construction of the long door or removable furnace front and the changes which must be made in the furnace construction to accommodate such a furnace front and for the power operated mechanism utilized in shifting it to and from normal closed position. The improvements in the furnace itself and in the removable furnace front which, as previously stated, may be provided with auxiliary doors or a size corresponding to those now employed at the front of the furnace, and the mechanism for shifting the furnace front and also for shifting the auxiliary doors either independently of or concomitantly with the movement of the fur-' nace front constitute the subject matter of other applications filed in our name. At the front of the furnace is the long horizontal opening 2| previously referred to, this opening being designed to be normally closed. by a movable front 22 which in some of the figures -(F igs. 4, 8, 9 and 13) is shown in closed. position and in other figures (Figs. 5, 6, and 7) in open position in front of and above the door opening;

Adapted to travel on-rails 23 of a runway is a novel charging machine 24 including a chassis 2 4a suitably provided with wheels which engage the rails 23. On the chassis 24a is a trolley or platform 24b which is movable toward and from .the furnace or at right angles to the runway. At the front of the platform 24b is provided a cradle 240 for the cold metal pan or container and distributor 25. The details of the charging machine per se form no part of the present invention as the same are claimed in a companion application, and for the purposes of this application it will be-sufflcient to state that the charging machine may have any suitable construction which adapts it for the support, movement, and manipulation of the cold metal container such that the latter is moved into the furnace, is actuated to discharge the cold metal therefrom in a manner such as to distribute it over the hearth, and is then withdrawn. Power operated mechanisms will be provided for the movement of the charging machine as a whole and :for the-movement of the platform and the container in carrying out the charging operation. The platform 24b may consist of a series of parallel interconnected I-beams supported by rollers so as to travel back and forth on the carriage 24a, and such construction is diagrammatically indicated, and the cradle 240 for supporting the container 25 is indicated as consisting of virtual extensions of the I-beams of the platform or trolley although of reduced size, note Fig. 9.

The cold metal container 25 may have any suitable construction by which it is adapted to receive the requisite amount-of cold metal and to cause the latter to be distributed over the hearth in the manner explained. In the embodiment of the invention here illustrated, the container'25 and, in fact, the charging machine as a whole are of a width only slightly less than the lengthof the hearth, itbeing contemplated (in this instance) that the length and width dimensions of the container correspond substantially to' the dimensions of the hearth, and that the cold metal be deposited on the bottom of the container in a layer with substantially the same character of distribution and thickness as it is to have later on the furnace hearth and also that the metal be transferred to the hearth over a wide area thereof and, in this case, over the entire hearth in a more or less uniform layer.

We have contemplated various methods of transferring the cold metal from the container to the floor of the hearth but now believe the best results are obtained by using a container in the form of a pan with a flexible rollingbottom capable of being rolled underneath the framework or body of the pan and of the cradle as the cradle is being withdrawn from the'furnace so that, in effect, the bottom of the pan is progressively withdrawn from the scrap or other cold metal, causing it to be spilled off the end of the pan bottom and progressively laid on the hearth. Accordingly,

.we prefer to use the cold metal container illus trated in Figs. 14 and 15. This container is composed of a lower framework including longitudinally extending I-beams 250. with two fixed upstanding sides 25b and with a flexible bottom 25c composed of overlapping plates linked or hingedly ,connected together with rollers 25d at the hinge points adapted to travel on flanges of the I-beams of the frame 25 or on other suitable tracks carried by the frame. At the rear of the flexible bot tom is an upstanding rear wall 25e here shown as inclined. The rear end ofthe flexible bottom is connected to the front end by a series of chains 25;! which at the rear side of the frame 25a. travel over rollers 259. At the front side of the container frame are rounded tracks 25h to accommodate the rollers 25d which in this instance are adapted to travel along the upper flanges of the I-beamsof the frame along the rounded tracks or guides 2511., onto the lower flanges of the I- beams, as is best shown in Fig. 15.

The container is adapted'to be supported by the cradle with the arms of the latter extending forwardly between the I-beams of the container frame and with their forward ends engaging between the flanges of a cross I-beam 25 i at the front side of the container frame. It will be seen that not only can the flexible container bottom travel like a conveyor around the container frame, but, after the loaded container, while supported on the cradle, has been inserted into the furnace, if then the platform or' trolley of the charging machine and the container frame are moved back, and if at the same time the rear end of the flexible container bottom is held stationary, as by the action of one or more holding beams 25k (see the right-hand end of Fig. 15) which are designed to be carried by the charging machine and are suitably operated at the will of the operator, the effect of rolling the container bottom around and underneath the container frame will be obtained. This explanation will make clear the previous statement that the container bottom is rolled back under the container frame from beneath the scrap or cold metal, causing the latter to be progressively dropped off the front edge of the container as the cradle and the container are withdrawn and while the rear end of the flexible container bottom is .held stationary relative to the furnace.

The details of the cold metal container per se form no part of the present invention, this container being claimed in a companion application, but we have described in some detail the construction of.the container herein illustrated to make clear its action in the cycle of charging operations.

In carrying out our process, the container may be handled or transported independently of the charging machine, and to be filled it is placed on the equivalent of a flat car by suitable hoist mechanism and conveyed away from the furnace building to a point adjacent the pile or piles of scrap where it is filled with the scrap or cold metal generally by a magnet supported by a trolley which runs on the bridge of a movable crane. The filled container is then brought back on the car beneath a movable crane or hoist tower, the yard level being usually below the level of the chargingfioor, as shown in Fig. 1 where the charging floor is indicated by the reference character 26, and which shows the filled container 25 on the car 21 with the hoist mechanism 28 ready to lift the filled container above the level of the charging floor. In this figure and in the subsequent figures the scrap or cold metal is des-- ignated by the reference character 29, the container and metal contents being in section in Figs. 1 to 8. Then the filled container is lifted to g ing machine may be caused to travel along the runway 23 to a position directly in front of the the furnace hearth which is only slightly larger than the former.

Then the furnace door or front is moved outwardly and elevated to the position shown in Fig. 5, after which the filled container is run into the furnace to the position shown in Figs. 5 and 10 by moving the trolley or platform 24b forwardly. Then the cold metal charge 29 is transferred from the container and is deposited in a layer over substantially the entire hearth by moving the trolley 24b back and withdrawing the container frame while holding the 'rear end of the flexible container bottom stationary in the manner previously described so as to cause it to be run under the container frame, with the result that the container is virtually withdrawn from beneath the metal. charge and the latter is progressively deposited in a layer over substantially the entire hearth, this layer being of substantially uniform thickness or as uniform as permitted by the somewhat rounded shape of the hearth.

In Figs. 6 and 11 are shown the parts in the positions which they occupy at about the middle of the operation of transferring the metal from the container to the hearth, while in Figs. '7 and 12 are shown the parts when the charging operation is completed, it being noted by reference to Figs. 5-, 6, and '7 that from the beginning to the end of that part of the operation wherein the layer of metal is transferred from the container onto the hearth the rear end of the container is held stationary. Next, the cradle and the now empty container are withdrawn by moving the charging machine carriage or platform 24a backward to the position shown in Figs. 8 and 13 during which operation the flexible container bottom is restored to its normal position, as best shown in Fig. 8. Next, the. movable furnace door or front is restored to position, as shown in Figs. 8 and 13, after which the melting operation may be initiated.

The above cycle of cold metal charging operations is preceded by a similar cycle during which the hearth is supplied with a layer of limestone which generally constitutes part of the charge, and, in the preceding description, when reference is made to depositing cold metal on the hearth,

this is to be interpreted as depositing the cold metal charge either directly on the hearth or over a previously applied layer of-limestone. Possibly in some instances the limestone and the cold metal charge may be applied simultaneously or in one charging operation.

From the above it willsbe seen that the'advantages and objects of the invention set forth at the beginning of the specification are attained to a high degree, with the further advantage that less cutting and sorting is required in preparing the scrap than is required with the relatively small charging box heretofore used since the cold metal pan or container here used is of such relatively large size that larger pieces of scrap can be utilized than heretofore and considerably less care exercised in loading the present pan or cold metal container than in filling a charging box.

It was mentioned heretofore that the charging of. the furnace with cold metal may be accomplished in two or more charging operations. This means either that a smaller charging machine and a smaller cold metal pan or container will be employed or that a section only of a full sized successively to two or more contiguous sections of the hearth in a corresponding number of charging operations similar in all respects to that described above.

We are aware of the fact that it has been proposed heretofore to feed materials into a furnace by means of conveyors of different kinds in which event the materials handled are more or less comminuted and are capable of being discharged from a spout or narrow belt and generally such materials are supplied to'the conveyor from a hopper or equivalent device holding a quantity of material in bulk form. Obviously, such equipment would be wholly unsuited for charging an open hearth furnace with scrap or scrap and pig iron, and, furthermore, the method of charging a furnace or equivalent receiving member by a continuously discharging spout or conveyor, such as a screw conveyor or endless conveyor, to which material in bulk is supplied is not the method here involved which in one of its main aspects contemplates the arrangement of a charge of predetermined volume and dimensions outside of the furnace and then transferring the charge onto the hearth in a layer of substantially the same dimensions which it had outside of the furnace, this being entirely new so far as we are aware whether the charge thus supplied to the hearth constitutes the entire furnace charge or I slight modifications, we do not desire to be con- 7 fined to the precise steps herein described, particularly as to the equipment or apparatus employed in carrying out the process.

Having thus described our invention, we claim:

1. The method of charging an open hearth furnace with scrap metal comprising arranging the scrap metal on a flexible support in a'layer having substantially the plan dimensions the charge is to have when deposited on the furnace hearth, introducing the support into the furnace, and then maintaining the outer end of the flexible support substantially stationary while the inner end thereof is withdrawn and, thereby pro-v gressively and uniformly depositing said layer of scrap metal on the furnace hearth.

2. The method of charging an open hearth furnace with scrap metal comprising loading the scrap metal on a flexible support at a point remote from the furnace and arranging the metal thereon in a layer having substantially the plan dimensions the charge is .to have when deposited on the furnace hearth, transporting the loaded support to a point adjacent the furnace open ing, introducing the loaded support into the furnace. and then maintaining the outer end of the support substantially stationary while the inner end thereof is withdrawn and thereby progressively and uniformly depositing said layer of scrap metal on the furnace hearth.

3. The method of charging an open hearth furnace with metal comprising arranging the metal in a layer on a flexible support, introducing the support into the furnace, and then holding the outer end of the flexible support substantially stationary while the inner end thereof is withdrawn and thereby progressively and uniformly depositing said layer of metal on the furnace hearth.

4. The method of charging an open hearth furnace comprising loading'cold scrap metal on a support having a flexible bottom to thereby provide acharge of such metal outside the furnace in the form of a layer having plan dimensions corresponding with a substantial area of the hearth, introducing the loaded support into the furnace so that the charge is completely in the furnace, and then withdrawing the support and at the same time progressively discharging said layer from the flexible bottom and uniformly transferring the same onto the hearth during such withdrawal and as a single charging operation.

4 PAUL H. DOUGLAS.

JOHN F. ROGERS.

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