Device for recovering heat and fumes from slag resulting from the steel production cycle

Abstract

Described is a device for recovering heat and fumes from slag resulting from the steel production cycle which allows the heat emitted by the slag during the cooling to be used without the need to collect the slag in tubs which must then be transported to the cooling surface and tipped in order to discharge the slag; at the same time, this device allows the fumes and consequently the heat and the pollutants which the slag emits during the tipping and the time on the cooling surface to be conveyed and treated.

Claims

1. A device for recovering heat and fumes from process slag, characterised in that the device can be associated with a processing/production system from which it receives incandescent slag, the device comprising: a slag plane (1) on which the incandescent slag falls, delimited by side walls, the slag plane (1) and the side walls comprising steel sheets (9 and 10), the steel sheets being positioned one in front of the other and spaced from each other by spacer elements which are able to create between the steel sheets (9 and 10) a plurality of ducts (11) through which air circulates; a plurality of insulated conveyors (12 and 13) for conveying air, associated with at least one side wall at an outlet of the ducts (11), at least one of the conveyors introducing air into the ducts (11) and at least one conveyor sucking air from the ducts (11), the conveyors allowing the circulation of air in the ducts (11) which heats due to the heat emitted by the incandescent slag (6) present on the slag plane (1) and a suction hood (14) located above the slag plane (1), the hood (14) having a front door (15) which can be opened, a rear suction window (16) connected with a suction duct (17) and an upper opening (18) through which the incandescent slag (6) is discharged onto the slag plane (1).

2. The device according to claim 1, characterised in that it comprises a predetermined number of water heat exchangers (19, 20) located on internal walls of the hood (14) for the recovery by irradiation of the heat emitted by the incandescent slag (6).

3. The device according to claim 2, characterised in that the heat exchangers (19, 20) are located on internal side walls of the hood.

4. The device according to claim 1, characterised in that it also comprises means for thermal treatment of fumes produced by the incandescent slag (6) and sucked through the suction window (16), from the suction duct (17).

5. The device according to claim 1, characterised in that it also comprises means for treatment and suppression of pollutant components contained in the fumes produced by the incandescent slag (6).

6. The device according to claim 1, characterised in that the spacer elements are box-shaped elements.

7. The device according to claim 1, characterised in that the spacer elements are beams.

8. The device according to claim 1, characterised in that the spacer elements are tubular elements.

9. The device according to claim 1, characterised in that walls of the hood (14) are insulated.

10. The device according to claim 1, characterised in that the hood (14) is made of lightweight steelwork.

11. The device according to claim 1, wherein the device also comprises means for cooling of fumes produced by the incandescent slag (6) and sucked through the suction window (16), from the suction duct (17).

Description

(1) The device according to this invention is described below in a non-limiting embodiment by way of an example with reference to the accompanying drawings, in which:

(2) FIG. 1 shows an axonometric view of the device for recovering heat from the slag resulting from the steel production cycle according to this invention;

(3) FIG. 2 shows a plan view of the device according to this invention;

(4) FIG. 3 shows a side view, with some parts in cross section, of the device according to this invention;

(5) FIG. 4 shows a front view of the device according to this invention;

(6) FIG. 5 shows a schematic side view of the device according to this invention.

(7) With reference to the above-mentioned drawings, the device for recovering heat from the slag resulting from the steel production cycle according to a non-limiting embodiment shown by way of an example comprises a slag plane (1) on which the slag (6) is placed directly from the furnace; the slag plane (1) is higher than ground level and is closed on the right and left sides and on the bottom by walls (2, 3, 4), the front side is joined to the ground by an inclined plane (5) which allows mechanical means to remove the cold slag; the slag plane (1) comprises two steel sheet planes (7, 8) positioned one in front of the other kept integral with each other and suitably spaced at approximately 20 cm, using box-shaped elements or beams which create a series of ducts for the passage of the air forced by a turbine (not illustrated); the same construction technique of the slag plane (1) is adopted for the right and left walls (2, 3) which are made with an inner steel sheet (9) and an outer steel sheet (10) kept at a suitable distance of approximately 20 cm by box-shaped elements or beams which create a series of ducts (11) which join with those present in the slag plane (1) and which allow circulation of the air in the slag plane (1) and in the walls (2, 3).

(8) The upper face of the right and left side walls (2 and 3) in which the aeration ducts (11) lead out is joined with conveyors (12 and 13), one for delivery preferably connected to a turbine not shown, and one for suction through which the heated air is conveyed for the successive use.

(9) The steel sheets of the slag plane (1), of the side walls (2, 3, 4) and of the spacer box-shaped elements or beams must have a thickness and a strength such as to bear the weight of the slag which is poured on and of the means which will transit on the slag plane for removing the slag when cooled.

(10) Above the slag plane (1) on the side inside the side walls (2, 3, 4) and inside the outlets of the aeration ducts (11) and of the conveyors (12 and 13) there is a closed circuit suction hood (14), preferably with a truncated pyramid shape, made from lightweight steelwork and insulated externally.

(11) The hood (14) is equipped with an upper opening (18), suitably sealed with the ceiling, through which the slag at a temperature of approximately 1,500 C., therefore in the semi-liquid state, is discharged directly from the furnace onto the slag plane (1).

(12) The hood (14) is equipped with a front door (15) which can be opened to allow the entrance of mechanical means suitable for the removal of the cold slag (6); in the upper part of the rear side, the hood (14) is equipped with a window (16) to which is connected a duct (17) through which the fumes and the heat emitted by the incandescent slag (6) are conveyed for treatment and cooling.

(13) On the inner walls of the hood, preferably on the side walls, there are one or more water heat exchangers (19 and 20) by means of which the heat emitted by the slag (6) is recovered by irradiation, causing the fast raising of the water temperature, thus optimizing the recovery of heat, which can be used later.

(14) As already mentioned, the device for recovering heat from the slag resulting from the steel production cycle is positioned directly below the furnace of the steelworks, in such a way that the slag is discharged directly on the slag plane (1), the hot slag, at approximately 1,500 C., is placed uniformly on the slag plane (1) avoiding the creation of thick layers of slag, which on the contrary occurs with the tipping into the tubs in which the slag has a lower temperature, in which the cooling is not uniform nor fast and the recovery of heat is decidedly poor, rendering it useless.

(15) The heat emitted by the slag (3) inside the closed and insulated hood (14) heats the water which circulates in the heat exchangers (19 and 20), heats the air which circulates in a forced fashion inside the ducts (11) and the fumes suction duct (17) prevents the dispersion of heat and pollutants into the atmosphere.

(16) The front wall (15) of the hood which can be opened automatically allows the discharge of the cooled slag (6) using special means and without any risk for the operators, unlike the current situation, with the movement of the tubs containing the slag at a temperature of approximately 1,000/1,500 C.

(17) The device for recovering heat from the slag resulting from the steel production cycle can be made to the size suitable for the furnace which must use it and an average size can be approximately 12.5 m in length by 10.5 m in width.