The invention resides in a charging hopper system for an electro-arc furnace with a closure member that can be opened, a hopper-like containment with a discharge opening and at least one suction opening, and also in a method of filling the arc furnace.
DE 103 55 549 A1 discloses a similar system. However, in this system gases can be discharged to the ambient in an uncontrolled manner when a scrap material basket is unloaded.
It is the object of the present invention to essentially reduce the chances of environmental contamination during such a procedure.
This problem is solved by the features of the main claim. To this end, a closure is provided which closes a precharging chamber. This pre-charging chamber is separated from the hopper-like containment by a separating wall which can be opened. Furthermore, a movable push shield is arranged in the precharging chamber.
In order to fill the hopper-like containment with the push shield disposed in a rest position and the separating wall closed the closure member is opened. After the unloading of the scrap material into the pre-charging chamber the closure member is closed. Then after opening the separating wall the push shield moves the scrap material into the hopper-like containment.
Particulars of the invention will become more readily apparent from the following description of schematically shown exemplary embodiments.
Since the density of the scrap material (4) is less than one tenth of the density of the liquid steel, for example, 7850 kilogram per cubic meter, the material volume required for a melt cannot all be introduced at once into the furnace containment 10 but rather in steps. For example, for a tapping of 100 tons of liquid steel, an input of more than 200 m3 scrap metal is required.
In the steel works, the metal scrap is first stored for example separately depending on various scrap metal types and qualities for example, light scrap, automotive scrap, mixed metal scrap, scrap metal mixed with plastic etc. . . . In each case, a scrap metal basket 3 is filled for example in a predetermined filling sequence. The loading volume of the scrap metal basket 3 is in the exemplary embodiment for example 75 m3.
The loaded scrap metal basket 3 is then transported by a transport arrangement 2 for example a building crane 2 to a charging hopper system 20.
The scrap metal 4 may also be transported from the scrap metal yard to the charging hopper system 20 by means of other continuous of discontinuous transport systems.
The charging hopper system 20 comprises a precharging chamber 31 with a closure member 51 and a hopper-like containment 101. The pre-charging chamber 31 and the hopper-like containment 101 are separated by a separating wall 71 which can be opened.
The pre-charging chamber 31 is in the exemplary embodiment a box-like chamber with a volume of for example 130 m3 and an at least approximately level bottom 32. The bottom may also be inclined downwardly toward the separating wall 71 for example at an inclination angle of up to 15 degrees. The bottom 32 is formed for example by metal sheets or planks with a thickness of for example 100 millimeters which are mounted on support beams 33 such as I-beams, hollow profile beams with square or rectangular cross-sections etc., which extend in a transverse direction 25. These beams 33 are connected to a water-cooled support frame 21 of the charging hopper system 20. The support frame 21 serves at the same time as a water distributor.
The side walls 26, 27 oriented in the longitudinal direction 24 of the charging hopper system 20 as well as the rear wall 28 are installed on the support frame 21. They may be removable for servicing purposes. The rear wall 28 is provided in the exemplary embodiment with a discharging opening 29. Also, the bottom 32 may include a discharge opening. For example, in the extension of the bottom 32 guide tracks are arranged in the side walls 26, 27, which are oriented in the longitudinal direction 24, see
The front wall of the pre-charging chamber 31 is formed in the representation of
The top side 34 of the pre-charging chamber 31 has, for example, a rectangular opening 35. The cross-sectional area of the opening 35 may correspond to the area of the bottom 32 or it may be smaller.
In the embodiment as shown in
In the exemplary embodiment, the wall surfaces of the funnel are not cooled. The angle of the funnel flanks with respect to the opening area 35 is for example 60°.
In the representation of
In the closed end position of the closing slide 52, the opening 35 is essentially hermetically closed. In the open end position of the closing slide 52 (see
It is also possible to arrange the closure member 51 between the opening 35 and the funnel 41. The closing slide 52 may then be correspondingly smaller.
In the precharging chamber 31 further a push shield 61 is arranged. This is a plate which extends in the charging hopper system 20 oriented in the transverse direction 24 and which is a reinforced plate with a thickness of for example 100 millimeter. In the representation of
The push shield 61 may also be curved along a horizontal and/or vertical bending line. The bending line is disposed in each case on the push side 62 of the push shield 61 facing the separating wall 71.
In the start-out position 64 as shown in
The push shield 61 and the separating wall 71 form in the exemplary embodiment front walls 61, 71 of a slide basket 81. For example, the six support beams 82 which interconnect the separating wall 71 and the push shield 61 have together for example a tension cross-section of at least 1000 square millimeter. The individual support beams 82 may be formed as full or hollow profiles. The side surfaces 83 of the slide basket 81 which is open at the top and at the bottom and, in the exemplary embodiment, are lined with metal sheets of a thickness of 30 millimeters. The maximum accommodation volume of the push basket 81 is in the exemplary embodiment 10% greater than the volume of the scrap metal basket 3. The upper horizontal support beams 82 may be in the form of step webs which guide the basket 81 along its path of movement.
The push shield 61 and the separating wall 71 are fased in the lower area in a transverse direction 25, see
On the push shield 61, a drive unit 91 is arranged which is supported by the pre-charging chamber 31 or the hopper-like containment 101, see
The hopper-like containment 101 has for example an overall volume of 200 m3 and includes in a vertical direction four areas 111-114. In all areas 111-114, the hopper-like containment 101 has an at least approximately rectangular cross-section in a horizontal plane and smooth walls 102. In the lowest area, it may be slightly conical with downwardly decreasing cross-section. The hopper-like containment 101 may be arranged in the longitudinal or in the transverse direction next to the pre-charging chamber 31.
The uppermost area 111—its height is about 40% of the containment height—has at least in one of the front walls which are oriented in the transverse direction 25, a suction opening 131 for the connection of a suction line 130, see
In this uppermost area 111, the guide tracks 22 extend for example up to the uncooled wall 102 which delimits the hopper-like containment in the longitudinal direction 24. In the direction of the precharging chamber 31, this area is delimited in the representation of
In the second area 112, the cross-section of the hopper-like containment 101 becomes smaller in the transverse direction 25 along the side walls 104 from the top to the bottom, see
The third area 113 has a constant cross-section. Its height is for example 25% of the height of the hopper-like containment 101. This area 113 may be omitted if the hopper-like containments 101 second area 112 is extended down to the lowermost area 114.
The lowermost area 114 is provided for example at the side wall 103 with a discharge opening 106. This discharge opening corresponds for example to an opening 11 of the furnace containment 10 of the electric arc furnace 5. This opening 106 is in communication for example with an opening 11 through which the scrap material is transported out of the hopper-like containment 101 into the furnace containment 10 of the electric arc furnace 5.
For the movement of the scrap material 4 in the area of the hopper-like containment 101 the charging hopper system 20 includes for example a pusher arrangement 151. By a displacement of a pusher 152 of the pusher arrangement 151, individual portions of the scrap material 4 are moved into the containment 10.
The scrap material 4 may also be moved out of the hopper-like containment 101 by gravity, by a pivot arrangement, by a vibration arrangement, by a pull drive etc.
At the side of the charging hopper system 20 facing the furnace containment 10, an exhaust gas line 141 is arranged whose upper end extends to the hopper-like containment 101. The wall of this exhaust gas line 141 consists of water-cooled pipes 142. In the exhaust gas line 141, an adjustable flap 143 is installed. This may be, as shown, a so-called butterfly flap or lamella flap.
In the exemplary embodiment, the whole charging hopper system 20 is movable. For example, the system 20 can be moved by means of a drive end and rollers 161 by a stroke length of about two meters away from the furnace containment 10. In this way, servicing work on the furnace containment 10 or the removal of the furnace containment is facilitated.
In order to charge the scrap material 4, first the filled scrap basket 3 is positioned by a building crane 2 over the closure member 51. The push shield 61 is in the start-out position 64, the separating wall 71 is closed. Upon opening the closure member 51, the scrap basket cover sheets 6 are for example hydraulically opened. The scrap metal pieces 4 fall into the precharging chamber 31 between the push shield 61 and the separating wall 71, that is, in the exemplary embodiment, into the push basket 81. After the scrap material basket 3 has been emptied, the basket 3 as well as the closure member 51 can again be closed. The charging hopper system 20 is now completely closed.
As soon as the level of the scrap material 4 in the hopper-like containment 101 is below a predetermined limit value, the scrap material can be moved out of the precharging chamber 31 into the hopper-like containment 101. The level may be determined for example by means weight sensors 162.
To this end, the push basket 81 is moved by means of the drive unit 31 into the front end position as shown in
Now scrap material 4 can be moved by a pusher arrangement 151 into the furnace containment 10. With the ignition of the electrodes 12 in the scrap material 4, the melting process starts. The suctioning device draws the exhaust gases formed during the melting process through the hopper-like containment 101 into the suction opening 131. Also, part of the exhaust gases may be drawn out via the exhaust gas line 141—depending on the position of the flap 143.
The exhaust gases heated by the melting process transfer part of their energy to the scrap material 4 disposed in the hopper-like containment 101 upon flowing therethrough. The scrap is in this way preheated while, at the same time, the exhaust gases are cooled.
In the startout position 64, the push basket 81 can again be filled as described above. This is shown in
By means of the push arrangement 151, additional scrap material 4 is transported into the furnace containment 10 in certain intervals and the melting process is continued. As soon as the scrap 4 level in the hopper-like containment 112 is below the mentioned limit value the next content of the push basket 81 can be moved into the hopper-like containment 101 without interruption of the furnace melting process. This occurs as described above. After delivery of the second push basket volume, the scrap material 4 is disposed for example as shown in
During further operation, the exhaust gases pass through the whole scrap column so that all of the scrap material 4 in the hopper-like containment 101 is preheated. By means of the pusher arrangement 151, additional scrap material is moved into the furnace containment 10 so that, with progressing time the height of the scrap column drops. As soon as it drops below the mentioned limit value, the push basket moves again into the startout position 64, see
The push basket 81 has a spindle unit 87 which extends around the threaded spindle 86. The separating wall 71 has in the area of the threaded spindle 86 an opening 74 which is sealed for example by a movable disc and a labyrinth seal.
For moving the push basket 81, the threaded spindle 86 is driven by a hydraulic motor 95, which may include a gear drive. If necessary such a threaded spindle 86 with a spindle nut 87 may be arranged at each side of the push basket 81. The arrangement is operated by one or two hydraulic motors. Under certain conditions also electric motors may be used.
Another drive variant is shown in
It is also possible to use a single rope tackle 96, 97. Depending on the direction of rotation of the motor 95, the push shield side or the separating wall side rope section 96, 97 is then pulled and the push shield 61 is moved either into the startout position 64 or to the end position 65.
In such an embodiment, the lift protection and/or the support rollers 88 may be omitted. Instead, the rope tackle may be arranged to extend inclined upwardly or downwardly. It is also possible that the push basket 81 is supported by a tensioned rope. A centering is achieved in each case by a guide metal sheet 68, and, upon reaching the end positions 64, 65, by the separating wall 71 and the seal wall 76.
The separating wall 71, see
For moving the scrap material 4 out of the precharging chamber 31 into the hopper-like containment 101, the movable push shield 61 pushes the scrap material 4 in the direction toward the hopper-like containment 101. The scrap material pushes the separating wall 71 open which pivots in the representation of
During the return movement of the push shield 61, the separating wall 71 flips again into its for example vertical startout position under the influence of gravity. In this position, it seals again the precharging chamber 31 and the hopper-like containment 101 with respect to one another.
The separating wall 71 may also be independently movable and also be pivotable by a drive.
In
In the push shield 61 additionally an impact structure 77 may be arranged. This impact structure 77 may for example be of the same design as the push arrangement 151 of the charging hopper system 20. The impact shield 78 of this impact structure 77 can move relative to the push shield 61. Herein, the push shield is in the shown basic position in alignment with the push side 62 of the push shield 61. From this position, it may be moved for example by one meter in the direction toward the center of the hopper-like containment 101. The width of the impact shield 78 may correspond to the width of the push shield 61 or it may be smaller than the push shield 61. The impact shield 78 may comprise separate segments.
Also combinations of the various exemplary embodiments are possible.
Number | Date | Country | Kind |
---|---|---|---|
102010045825.2 | Sep 2010 | DE | national |
This is a Continuation-In-Part application of pending international patent application PCT/DE2011/001741 filed Sep. 20, 2011 and claiming the priority of German patent application 10 2010 045 825.2 filed Sep. 20, 2010.