The invention relates to a method for repairing an existing coke oven battery with a plurality of coke oven chambers, wherein each chamber has two opposite coke oven walls, comprising tearing down at least one of the existing coke oven walls during operation of the coke oven battery, and establishing a new coke oven wall to replace the torn down coke oven wall.

The invention further relates to a prefabricated coke oven wall for use in this repair method, and to a heavy lift construction for lifting and moving such a prefabricated coke oven wall .

Coke oven factories comprising a plurality of coke oven batteries, wherein each of the batteries comprises a series of coke oven chambers, are ancient art and used throughout the world to provide cokes for application in blast furnaces that are employed in the iron and steel industry. Coke oven factories are capital intensive and therefore downtime should be avoided as much as possible. This implies that when a coke oven factory has to be repaired, the repair time should be minimized. This is a first objective of the invention.

In existing repair methods according to the prior art, the repair is carried out during operation of the coke oven batteries whereby the repair personnel operates within the battery limits of the coke oven battery. This may cause disruption of the coke oven production leading to higher costs. It is a second objective of the invention to reduce disruptions of the production and to limit costs .

As just mentioned the repair personnel operates within the battery limits of the coke oven battery for the repair of the coke oven chambers. It goes without saying that the working conditions for such personnel are very stressful considering for one thing that the ambient temperature is approximately 50 °C. This means that during demolition of the existing coke oven walls as well as during the reconstruction of the new walls, the maximum working time is limited and frequent rests are required by law. It is a third objective of the invention to improve these working conditions. In order to promote the objectives of the invention it is proposed to implement the method for repair of an existing coke oven battery with a plurality of coke oven chambers in accordance with one or more of the appended method claims . Further it is proposed to apply in this method and according to the invention a prefabricated coke oven wall and a heavy lift construction for lifting and moving such a prefabricated coke oven wall in accordance with the appended claims that are directed to this particular subject-matter.

As indicated hereabove according to the prior art repair of an existing coke oven battery involves demolition of the existing coke oven walls by personnel working within the battery limits. According to one aspect of the invention tearing down of an existing coke oven wall is executed by operating a crane which is movable on top of the coke oven battery, and which crane is provided with a breaking and/or gripping tool having a reach to the bottom of a coke oven chamber. This breaks with the habit of the prior art to execute the repair entirely from within the battery limits of the coke oven battery. Applying such a crane improves the ease of demolishing the existing coke oven walls, and further obviates the need to have the personnel work within the battery limits of the coke oven battery. The . working conditions are therefore less harsh than in the prior art .

In order to enable that the crane can move on top of the coke oven battery it is preferred that the crane is movable over first rails, preferably the existing larry car rails on top of the coke oven battery, and that prior to operating the crane for tearing down an existing coke oven wall, a section of the larry car rails immediately above that coke oven wall is reinforced. This reinforced section of the rails can also be used furtheron in the method when the new coke oven wall is established on the spot where earlier the previously existing coke oven wall stood. This will be explained hereinafter.

By arranging that the crane is movable over the larry car rails of the coke oven battery, it is not necessary to spend costs for another set of rails.

A further preferred feature of the method of the invention is that a U-profile is placed on the bottom of the coke oven chamber for receiving debris from the existing coke oven wall that is being demolished. In this way it is possible in an easy way to avoid that such debris remains within the coke oven chamber by arranging that on a regular basis the U-profile is swept clean by for instance applying a chain conveyor.

Another aspect of the invention concerns the erection of a new coke oven wall on the place where, prior to its demolishing, the earlier coke oven wall stood. According to the prior art the erection of the new coke oven wall is implemented by bricklaying within the confines or battery limits of the coke oven battery. This involves labor under severe working circumstances and may also disrupt the continuing production in the remaining coke oven chambers of the battery that are still employed for the production of cokes. According to the invention the new coke oven wall is prefabricated and placed into position in the coke oven battery after removal of the existing coke oven wall .

The placement of the new coke oven wall can then be simply carried out by initially lifting the prefabricated new coke oven wall from the place where it is erected and then moving it in front of the coke oven battery whereby the new coke oven wall extends outside of the battery limits of the coke oven battery, perpendicular with respect to the length-direction of said coke oven battery and parallel with the existing coke oven walls that are within the battery limits of the coke oven battery. Following these steps preferably the prefabricated new. coke oven wall is moved from a position in front of the coke oven battery to a position within the battery limits of the coke oven battery before it is placed in its final position supported on the bottom of a coke oven chamber.

In still a further aspect of the invention lifting and moving of the prefabricated new coke oven wall is executed with a heavy lift construction that is movable in front of the coke oven battery. Preferably the heavy lift construction is movable over second rails for a pusher machine of the coke oven battery, which is used during operation of the battery for pushing out the ready cokes. Again this arrangement limits costs and promotes that the placement of the new coke oven wall can be carried out swiftly.

Another aspect of the invention is that the heavy lift construction has a third rail from which the prefabricated new coke oven wall can be suspended, and that a fourth rail traverse to the direction of the first rails on top of the coke oven bat- tery is mounted below said first rails, wherein moving the prefabricated new coke oven wall from a position in front of the coke oven battery to a position within the battery limits of the coke oven battery is executed after aligning the third rail with the fourth rail. This secures a reliable operation and avoids that the new coke oven wall is subjected to undesirable stresses due to a bumpy transfer from the third rail of the heavy lift construction to the fourth rail wherein the new coke oven wall is suspended within the confines of the coke oven battery.

To further promote the smooth transfer of the new coke oven wall from the third rail to the fourth rail, desirably after the aligning of the third rail with the fourth rail a filler piece is placed between the third rail and fourth rail to assist the transition of the prefabricated new coke oven wall when moving from outside to inside the battery limits of the coke oven battery. Finally then placing the prefabricated new coke oven wall in its final position supported on the bottom of a coke oven chamber can be executed by lowering it from a rail on top of the coke oven battery from which the prefabricated new coke oven wall is suspended, until it rests on the bottom of said coke oven chamber .

An entirely new aspect of the invention is that the new coke oven wall is prefabricated by bricklaying it on a supporting metal beam which is arranged to cooperate with a heavy lift construction for lifting and moving the coke oven wall. It is this thought which has heavily contributed to the breakthrough according to which the huge savings come into reach that are possible with the invention in comparison with the prior art method of repairing a coke oven battery.

Desirably the first layer of bricks on the supporting metal beam comprises bricks of fused silica. These fused silica bricks are free from thermal expansion and this first layer can therefore be implemented with dimensions that reliably satisfy the dimensions of regular silica bricks at their elevated operating temperature.

For the same reason it is further desirable that before placing the prefabricated new coke oven wall in position within the battery limits of the coke oven battery, a supporting layer of fused silica bricks is placed on the bottom of the concerning coke oven chamber. Upon placement of the prefabricated coke oven wall this latter layer of fused silica bricks supports the fused silica bricks of the prefabricated coke oven wall without risk that cracks will develop due to differences in thermal expansion .

In view of the previous description it will be appreciated that the invention is amongst others embodied in a prefabricated coke oven wall having the feature that a lower layer of bricks of the wall consists of fused silica bricks.

In order to promote the ease of handling of this prefabricated coke oven wall it is preferred that the lowest layer of bricks of the wall has a cutaway enabling the accommodation of a beam which is capable to be used for lifting the ready wall . In this manner undesirable stresses in the wall due to its lifting and handling can be avoided.

It is further desirable that immediately on top of the layer of fused silica bricks of the wall is a sliding joint on top of which regular silica bricks are laid. The sliding joint accommodates that the dimensions of the regular silica bricks can vary with respect to the dimensions of the fused silica bricks as a result of temperature variations.

The invention is further embodied in a heavy lift construction for lifting and moving a prefabricated coke oven wall, which comprises a left part and a right part of a cage for accommodating the prefabricated coke oven wall in between said parts.

Advantageously the cage is closable at it's underside by one or more means to keep the left and right part of the cage together. Preferably these means, for instance pull rods, are removable for enabling that the left part and right part of the cage can be removed from the coke oven battery after placement of the prefabricated new coke oven wall.

Further it is preferred that at least one of the left and right part of the cage is arranged to cooperate with a beam which is usable for supporting a lowest layer of bricks of the prefabricated coke oven wall.

In order to promote its effective use in the method of the invention, it is desirable that the cage is suspended from a rail such that the cage with the prefabricated coke oven wall contained therein can be lowered and raised with respect to said rail and moved in the longitudinal direction of such rail.

A further aspect of the invention is that it is desirable that the heavy lift construction is provided with leveling means to secure that the prefabricated coke oven wall can be properly aligned with respect to the coke oven battery.

The invention will hereinafter be further elucidated with reference to the drawing.

In the drawing:

-figures 1-18 represent an exemplary embodiment of a method of first demolishing an existing coke oven wall and then replacing it by a prefabricated new coke oven wall;

-figure 19 shows a cross-sectional view in detail of a coke oven chamber with a first layer of fused silica bricks, on top of which the lowest layer of the new prefabricated coke oven wall is placed;

-figure 20 shows in detail in cross-section the manner of lifting the prefabricated coke oven wall with the heavy lift construction; and

-figure 21 shows the lower part of the new prefabricated coke oven wall resting on the bottom of the coke oven chamber in its finished condition.

Wherever in the figures the same reference numerals are applied, these numerals refer to the same parts . Further the figures only show the parts of the coke oven battery that are required to elucidate the invention, the construction of the coke oven battery itself being well known to those skilled in the art, hence a full picture of this battery can be dispensed with .

Figure 1 provides an overview of a coke oven battery 1, a parking spot 2 which is normally used for the larry car running on top of the coke oven battery 1 and which will in the invention also be used for parking the crane 3 which is used in the method of the invention. Further at 4 the place is indicated where the bricklaying of the new prefabricated coke oven walls can occur, and with reference 5 the heavy lift construction of the invention is identified. Figure 1 further shows first rails embodied as larry car rails 12 on top of the coke oven battery 1, and second rails 13 in front of the coke oven battery 1. The larry car rails 12 are normally used by a larry car for filling the coke oven battery 1 with coal that is to be converted to cokes. The second rails 13 are normally used by a pusher machine of the coke oven battery 1 to push out the cokes when ready.

Figure 2 shows the coke oven battery 1 having the crane 3 running on top of it during preparatory work for the removal of the columns 11 of the coke oven battery 1. The crane 3 is movable over the larry car rails 12 on top of the coke oven battery 1 and is embodied with a breaking or gripping tool 6. Part of the preparatory work is shown in figure 3 which relates to the placement of reinforcement beams 7 next to the larry car rails 12 at the location where the repair work is to be executed. After finalization of this preparatory work which may also include placing a U-profile on the bottom of the concerning coke oven chamber (not shown) for receiving debris resulting from the demolishing work, the deck 8 of the coke oven battery 1 is removed as shown in figure 4. Figure 5 shows the subsequent removal of the existing coke oven walls 9 that have to be replaced by new prefabricated coke oven walls in accordance with the invention.

Figure 6 shows the placement of an additional supporting beam 10 which will furtheron in the method be used for mounting a fourth rail 14 that will cooperate with a third rail of the heavy lift construction from which rails the prefabricated new coke oven wall will be suspended during its placement in the coke oven battery 1. In figure 7 three additional supporting beams 10 are shown as well as the just mentioned fourth rail 14 which is oriented perpendicular to the larry car rails 12 and the supporting beams 10.

Prior to or immediately following the demolishing work isolation screens may be placed to counteract the loss of heat from the neighboring coke oven chambers in which production of cokes continues . This is not shown in the figures but it is clear for persons skilled in the art how this must be implemented, without therefore requiring that same is shown in the figures.

After completion of the demolishing work and removal from the debris resulting therefrom, a supporting layer of fused silica bricks 15 is placed on the bottom of the concerning coke oven chamber, which is shown in figure 8 and shown in cross- sectional detail in figure 19. Then the prefabricated new coke oven wall can be placed on the fused silica bricks 15, for which purpose the new coke oven wall 9 can be picked up from location 4 shown in figure 1. The picking up operation is shown in figure 9.

At this point of the elucidation of the invention reference is made to figure 20 showing in cross-section the lower part of the prefabricated coke oven wall 9 and the manner of lifting same with the heavy lift construction 5 of the invention. Figure 20 shows that the prefabricated coke oven wall 9 is embodied with a lower layer of bricks 16 from fused silica.

These fused silica bricks 16 are provided with a cutaway 17 in which a beam 18 can be accommodated. During production of the coke oven wall 9 first the lowest layer of bricks 16 are laid on the beam 18, followed by further bricklaying of regular silica bricks 19 on top of the fused silica bricks 16 with an sliding joint 20 in between these two lowest layers 16, 19. After completion of the bricklaying the ready-made coke oven wall 9 can then be lifted by supporting the beam 18 by a lower extension from (for instance) a right part 22 of a cage 23 that forms part of the heavy lift construction 5.

Figure 10 shows the ready prefabricated coke oven wall 9 after it has been picked up. The coke oven wall 9 is then contained between a left part 21 and a right part 22 of the cage 23 that forms part of and is suspended within the heavy lift construction 5. The left part 21 and right part 22 of the cage 23 are kept together by means of pull rods 26, one of which is shown in figure 20.

After the coke oven wall 9 is picked up, it is moved by the heavy lift construction 5 to a position in front of the coke oven battery 1 as is shown in figures 11 and 12. In figure 12 the coke oven wall 9 is lifted to the level of the coke oven chamber in which it is to be placed, yet in this position the new coke oven wall 9 that is suspended from a third rail 24 forming part of the heavy lift construction 5, still extends outside of the battery limits of the coke oven battery 1. It is important that the new coke oven wall 9 is aligned such that it extends parallel with the existing and remaining coke oven walls that are within the battery limits of the coke oven battery 1.

Prior to moving the coke oven wall 9 to its position in the coke oven chamber within the battery limits of the coke oven battery 1, the third rail 24 from which the wall 9 is suspended within the heavy lift construction 5, and the fourth rail 14 that is mounted to the larry car rails 12 and to the supporting beams 10 on top of the coke oven battery 1 are aligned. After their aligning the third rail 24 and the fourth rail 14 are connected by means of a filler piece 20 as is shown in figure 13, to secure a smooth transfer when the new coke oven wall 9 is moved from outside to inside the battery limits of the coke oven battery 1.

Figure 14 shows the coke oven wall 9 when it has been moved into the coke oven battery 1 and placed upon the fused silica bricks 15 on the bottom of the concerning coke oven cham ^¬ ber. In figure 19 it is shown that the lower layer of fused silica bricks 16 of the coke oven wall 9 then comes to rest on the fused silica bricks 15 on the bottom of the coke oven chamber. Figure 21 shows that eventually a fused silica tile 27 can be placed within the cutaway 17 after removal of the cage 23 and removal of the beam 18 which has been used to support the coke oven wall 9 during its manipulation by the heavy lift construc ^¬ tion 5 as explained hereinabove with reference to figure 20.

Figure 15 shows the retraction of the cage 23, and fig ^¬ ure 16 provides a view of the coke oven battery 1 after a further two prefabricated coke oven walls 9 are placed within the coke oven battery 1. For sake of completeness it is remarked that in order to enable the retraction of the cage 23 it is clear that first the pull rods 26 that connect the left part 21 with the right part 22 of the cage 23, have to be removed.

Figures 17 and 18 finally show the placement of a new deck on top of the coke oven battery 1, and the completed coke oven battery 1 respectively.

In summary the inventors have found that working in accordance with the invention results in improved working conditions, savings in required time to carry out a repair of an existing coke oven battery of approximately 50% in comparison with the prior art repair method, and approximately 30% cost reduction due to reduced disruption of coke-production.