GB2131933A

GB2131933A - Installation for charging industrial furnaces

Info

Publication number: GB2131933A
Application number: GB08333540A
Authority: GB
Inventors: Gunther Schmidt; Joseph Koch
Original assignee: Strikfeldt & Koch; Strikfeld W and Koch GmbH
Current assignee: Strikfeldt & Koch; Strikfeld W and Koch GmbH
Priority date: 1982-12-18
Filing date: 1983-12-16
Publication date: 1984-06-27
Also published as: GB2131933B; GB8333540D0; NL8304285A; DE3247023A1

Abstract

An installation for charging an industrial furnace, particularly a metal smelting furnace, comprises a charging cage (8) with openings (11) for passage of flue gas in its floor (10), means for mounting said cage for swivelling about a pivot axis and a drive installation (13) for swivelling the cage (8) between a charge pre-heating position and a charging position (8'). The installation is to be installed in an industrial furnace in a flue stack (6) so that the cage (8) is above a smelting chamber (2). <IMAGE>

Description

SPECIFICATION Installation for charging industrial furnaces This invention relates to an installation for charging industrial furnaces, in particular metal smelting furnaces, with pre-heating of the charge by utilization of flue gas heat, with a charging and pre-heating apparatus arranged in the flue gas stream, which has openings for the passage of the flue gas and is movable from a pre-heating position to a charging position by means of a drive installation.

Such an installation is known from German laid-open specification 29 51 826. The charging and pre-heating apparatus here consists of force-cooled grids arranged above the melt vessel, which grids are run apart horizontally to throw down the pre-heated charge. In doing this the charge or material to be melted falls unbraked into the metal bath, which has damaging consequences both for the metallurgical process and for the durability of the cladding material of the furnace. It is also disadvantageous that the grids which run in guides have different temperatures at different parts and at times are heated and then again cooled. This can lead to distortion and warping of the grids. Further the grids are of relatively large dimensions.

German laid-open specification 28 1 5 229 further disclosed a charging installation for metal smelting furnaces, in which the material to be melted by means of a charging container is discharged into a small charging basin in communication with the actual furnace space. The charging container here comprises a tiltable vessel which can be both tilted and lifted and lowered by means of rollers arranged on roller guides extending upwards from and above the charging basin.

The charging container has a grid-like floor through which radiant heat from the top surface of the metal bath can heat the charge.

However there is no utilization of flue gas heat.

The aim of the invention is to make an installation of the above-mentioned type, with reduced constructional and space requirements, so that there is good utilization of flue gas for pre-drying and pre-heating the charge or material to be melted respectively, and so that dosed charging of the furnace is possible without damaging disturbance of the melt bath.

According to the invention there is provided an installation for charging an industrial furnace comprising a charging cage with openings for passage of flue gas in its floor, means for mounting said cage for swivelling about a pivot axis and a drive installation for swivelling the cage between a charge pre-heating position and a charging position.

Preferably the floor of the charging cage is formed as a cylinder segment, which results in a large fiiling capacity and large surfaces around which flue gas can stream.

The floor of the charging cage may consist of a grid or the like. Cooling means, such as an air cooling system, water cooling system or evaporation cooling elements, may sometimes advantageously be provided for the floor and possibly also for the sides of the cage, to suppress wear damage and to avoid having any softened charge stick to the floor of the cage. Particulariy if the coolant heat content is to be utilized the charging cage and in some cases also some regions of the flue stack may be fitted with so-called evaporative cooling elements in which cooling water evaporates or, as the case may be, is vaporized.

This cage is for installation in an industrial furnace, particularly a metal smelting furnace, where there will be a smelting chamber and above it a flue stack in which the cage is pivotally mounted, preferably about a substantially horizontal pivot axis.

Thus according to the invention for predrying and pre-heating and for charging the furnace a charging cage is used which is arranged to be fully in the flue gas stream and thus to have flue gasses streaming on all sides through and around it. As the charging cage has no cooler component parts lying outside the flue gas stream and also does not require to be removed out of the flue stack for charging while being subject to cooling down, it is on the whole only subject to even and constant heating, so that damaging distortion and warping of the charging cage is avoided.

The pivotal bearings of the charging cage may, like the swivelling drive, lie outside the cross-section of the flue shaft through which the flue gasses stream. The charging cage can be made with a sufficiently large fill content with relatively small dimensions. By means of the charging cage the material to be melted can be dosed, and so delivered to the smelting chamber that no damaging disturbances of the meltbath occur. The pre-heating installation can also be built into existing installations without too great expenditure.

In a preferred embodiment the charge cage is mounted above a smelting chamber which is joined to and communicates with a collecting and keeping-hot chamber formed in the funace for receiving molten metal. The smelting chamber simultaneously forms a charging chamber which can have relatively small dimensions, as for storage the separate collecting and keeping-hot chamber is provided in which latter the molten bath is not subject to any damaging disturbance.

In a preferred embodiment the charging cage is arranged in a flue stack which is funnel-shaped, broadening out upwards of the smelting chamber. This embodiment makes it possible to construct the charging cage with relatively large cross-dimensions or width re spectively and for the charge to be delivered to the smelting chamber relatively gently and without falling any great height on swivelling of the charging cage, whereby optionally the funnel-shaped broadening of the flue stack forming an inclined ramp may serve as a ramp slide for the charge, which ramp slide may be provided with cooling means. The flue stack may suitably be continued upwards into a flue gas shroud which has at its periphery a charging opening for allowing charging of the charging cage.

'The pivot axis of the cage preferably lies substantially in the vertical central plane through the smelting chamber. The width of the charging cage may be greater than that of the smelting chamber below it.

The invention will hereinafter be described in more detail with reference to the embodiment shown in the drawing. The drawing shows a side view of a smelting furnace according to the invention as well as of the charging and pre-heating installation according to the invention, partly in a vertical section.

The metal smelting furnace 1 illustrated comprises in one constructional unit a smaller smelting chamber 2, which is simultaneously a charging chamber, and connected in communication therewith a collection and keeping-hot chamber 3 for receiving the molten metal. The smelting chamber 2 is connected in the region of its base by a channel 4 to the collection and keeping-hot chamber 3 which lies to the side of and has a floor lower than that of the smelting chamber 2. The smelting chamber 2 is heated by means of one or more burners 5. During smelting the hot flue gasses depart via a flue stack 6 above the smelting chamber 2, which is continued upwards into a flue gas shroud 7 by which the flue gasses are directed, for example, into the open air.

The flue shaft 6 preferably is funnel-shaped and broadens out upwards from the smelting chamber 2; in its upper region it is enclosed by flue gas shroud 7.

A charging cage 8 is positioned inside the flue stack 6 and the flue gas shroud 7, which cage can be swivelled about a pivot axis 9, which lies approximately in the vertical central plane of the smelting chamber 2 and the flue stack. The horizontal pivot axis 9 is mounted on the flue gas shroud 7 by swivel bearings, which lie outside the cross-section of the flue shaft through which the hot flue gasses pass.

Charging cage 8 has a floor 10 in the shape of a cylinder segment, provided with multiple openings 11 for the passage of flue gasses.

Preferably the floor of the charging cage 8 is grid-like. Floor 10 is firmly connected to two lateral walls 12 2 of charging cage 8. These lateral walls 1 2 may also be formed with openings for passage of flue gas. The pivot axis 9 is arranged on the side walls 12 of the charging cage. It can be seen that the width of the charging cage, that is its horizontal dimensioning, is greater than the width of smelting chamber 2. Otherwise the charging cage 8 is dimensioned to fit the funnel-shaped flue stack 6, and so mounted in the flue stack that hot flue gas passes by and through it on all sides.

A drive installation 1 3 is mounted on the outside of flue stack 6, by means of which the charging cage can be swivelled from the swivel position indicated by solid lines to the swivel position 8' indicated by the dot-dashed line, to deliver the charge or material to be melted into the smelting chamber 2. Drive installation 13 may consist of, for example, a drive motor which swivels the charging cage via a transmission and a chain drive.

A closable charging opening 14 is positioned circumferentially on the flue shaft or flue gas shroud respectively. The charging cage 8 is filled with charge to be melted by means of a charging installation 15 mounted on the outside of the smelting furnace. This comprises a charging container 1 6 which can be lifted and lowered as well as tilted, which when the charging opening 14 is open can be introduced into the flue shaft and tipped to transfer the charge to be melted into the charging cage 8. A pile of light metal pigs is indicated in the drawing at 17, which can be transferred to the charging cage 8 by means of the charging container 1 6.

After the charging vessel 16 has poured the charge, for example the pile 1 7 of light metal pigs, into the charging cage 8 and has returned to its initial position in the region of the base of the furnace, the charging cage 8 is by means of the drive installation 1 3 slowly swivelled clockwise into the dot-dashed swivel position 8'. During this the charge slowly falls out of the charging cage into the furnace stack or the smelting chamber 2 respectively.

The arrangement is such that the charge can slide down the funnel-shaped interior surface of the flue stack 6 into the smelting chamber, with this funnel-shaped surface forming an inclined ramp slide.

As soon as the charging cage 8 is emptied it is swivelled back into its fully drawn out initial position and filled anew with charge in the manner described. Until the charge to be melted has been melted down sufficiently in the furnace for the latter to take up new charge, all the hot flow gasses from the melt chamber 2 brush through the perforated floor of the charging cage to the flue gas shroud, whereby the charge in the charging cage is dried and pre-heated.

It may serve a useful purpose to cool the charging cage 8, and in particular its cylindrical floor 10 wholly or paritally to reduce the stresses on the cylindrical cage and to prevent any already somewhat softened charge from sticking to the cage. For this the charging cage 8 may be fitted with per se known evaporative cooling elements through which water flows, particularly if the coolant heat is also to be usefully exploited. It is also possible to provide cooling means for the surface of the flue stack 6 down which the charge slides into furnace chamber 2.

The whole installation may be controlled manually or also automatically. It makes posible good utilization of the flue gasses to preheat the charge to be melted, whereby substantial savings on energy and costs can be achieved. It is also of importance that with the installation according to the invention effective pre-drying of the charge or material to be melted can be achieved in an initial step. For example dangerous explosions may occur if charge stored in damp or wet conditions, for example with adhering ice or snow, is discharged into liquid aluminium. This danger is effectively avoided by the pre-drying of the charge in the charging cage. In the case of pre-drying there is simultaneously an advantageous pre-cleaning of the charge or other material or scrap or the like, as harmful pollutants such as adhering deposits, dirt or small plastics rests or the like burn up and thus do not come into contact with the liquid melt.

This produces a metallurgical benefit.

Claims

1. Installation for charging an industrial furnace comprising a charging cage with openings for passage of flue gas in its floor, means for mounting said cage for swivelling about a pivot axis and a drive installation for swivelling the cage between a charge preheating position and a charging position.

2. Installation according to claim 1 wherein the floor of the cage is formed as a cylinder segment.

3. Installation according to claim 1 or 2, wherein the floor of the cage consists of a grid.

4. Installation according to one of claims 1 to 3, wherein cooling means are provided for the floor of the cage.

5. Installation according to claim 4 wherein said cooling means comprises an air cooling system or a water cooling system or evaporative cooling elements.

6. An industrial furnace comprising an installation as claimed in one of claims 1 to 5, said furnace comprising a smelting chamber and above it a flue stack in which the cage is pivotally mounted.

7. An industrial furnace according to claim 6 wherein the smelting chamber is connected to a collecting and keeping-hot chamber.

8. An industrial furnace according to claim 6 or 7 wherein the cage is mounted for swivelling about a substantially horizontal pivot axis.

9. An industrial furnace according to claim 8 wherein the cage is mounted for swivelling about pivot bearings which lie outside the cross-section of the flue stack through which flue gasses stream.

10. An industrial furnace according to one of claims 6 to 9, wherein the flue stack is funnel-shaped, broadening out upwards of the smelting chamber.

11. An industrial furnace according to one of claims 6 to 10 wherein the flue stack continues up into a flue gas shroud which has at its periphery a charging opening to allow charging of the charging cage.

12. An industrial furnace according to one of claims 6 to 11 wherein there is an inclined ramp via which the cage delivers the charge to slide into the smelting chamber.

1 3. An industrial furnace according to claim 1 2 wherein the ramp surface over which the charge slides is provided with cooling means.

1 4. An industrial furnace according to one of claims 6 to 1 3 wherein the pivot axis of the charging cage lies substantially in the central vertical plane through the smelting chamber.

1 5. An industrial furnace according to one of claims 6 to 1 4 wherein the width of the charging cage is greater than that of the smelting chamber below it.

1 6. Installation for charging industrial furnaces substantially as hereinbefore described with reference to the accompanying drawings.

1 7. Industrial furnace substantially as hereinbefore described with reference to the accompanying drawing.

18. Industrial furnace according to one of claims 6 to 15, or 17, for use in smelting metal

1 9. Installation for charging industrial furnaces, in particular metal smelting furnaces, with pre-heating of the charge by utilization of the flue gas heat, with a charging and preheating apparatus arranged in the flue gas stream, which has openings for the passage of flue gas and is movable by means of a drive installation from a pre-heating position to a charging position characterised in that the charging and pre-heating apparatus consists of a charging cage (8), whose floor (10) has openings (11) and which can be swivelled about a pivot axis (9) by means of the drive installation (1 3).