REFRACTORY LINING OF COKE OVEN DOORS IN TWO SPACED LAYERS SO AS TO CREATE A ROOMY GAS FLUE CHAMBER

Abstract: This Patent covers the refractory lining of coke-oven doors consisting of 2-layer elements (1, 2) one of these layers being in touch with the door (3) and the other with the coke, the two layers being spaced so as to create a roomy hollow space or chamber (4) for a better upwards discharge of the coke oven gas without external losses, each element being provided with section iron mounting (7, 8) and bolts (9, 11, 12) for assembly of the two layers (1, 2) and to secure the element to the oven door (3). The various elements have different thickness so as to create a slope in the coke wall apt to prevent the coke from sliding down. The two layers are in different materials, i.e. layer 2 in touch with the coke has excellent mechanical properties, whereas the layer in contact with the door (3) has excellent insulating characteristics. (Fig. 3).

Description: This Patent covers the refractory door lining of coke oven chambers in which coal is coked to produce combustible "grid" gas and coke. It is known that these coke ovens are consisting of numerous chambers arranged in batteries, each chamber being closed at both ends by removable doors. These chambers are filled with coal and after the coking process and remo­ val of the two doors, the ovens are emptied by mechanical coke extractors. Obviously the doors as well as the inner walls of the coke ovens are lined with refractory material. A major problem for these coke ovens is the poor seal of the doors; especially during the initial coking stage when a large quantity of grid gas is produced, much of the gas escapes causing pollution of the environment and fire hazards. Another problem of these coke ovens is regarding the refractory door lining which has to be properly supported and has a rather short life due to thermal shock and mechanical stresses when the doors are opened and closed. Classical door linings are consisting of refractory bricks supported by cast iron stirrups or brackets. This solution involves considerable fettling costs and a considerable amount of gas escaping through the interstices between the door and front wall of the coking chamber, especially at the lower end and central part of the coke oven where the pressure is higher, even when additional mechanical seals are installed. These serious drawbacks have been mitigated, according to a known technique, by creating a vertical gas flue inside the refractory lining to improve the upwards gas flow in the oven, but this does not improve the conditions in the central part of the oven. Another refractory lining system is known, according to the Italian patent n° 12531 A/82 by which the situation is further improved. In this Patent, the vertical stack has numerous small double transverse ducts, opening up on the side walls of the refractory so that the gas can escape even in the central part of the coking chamber and can be conveyed to the zone above the coking coal. This reduces the gas pressure and external losses although not yet enough, especially during the initial coking stage. The solution according to this known Patent has also other drawbacks: First of all, the lateral ducts may be obstructed by slag and deposits. A second disadvantage is due to the fact that the various refractory elements are in one single piece of considerable thickness, so that repair and fettling costs remain high while the working volume of the coke oven remains rather limited. The supporting structures on which to mount and secure the refractory blocks are also rather complex, although in this approach the refractory lining is installed on assembled steel structures and not on cast iron. A hollow space to be filled with insulating material is provided between the inner door wall and the refractory and this too involves additio­ nal installation costs. This Patent has the aim: - completely to eliminate gas leakes and the related pollution and fire hazards; - to increase the capacity of the coke oven - to prevent coke from falling when the oven doors are opened; - to eliminate the normal use of door cleaning devices to remove the slag deposited along the door edges; - to increase the insulating capacity of the doors; - to improve the mechanical strength of the refractory material; - to reduce the weight of the door-refractory assembly; - to cut the costs for repair, fettling or replacement of the whole door. These objectives are reached, according to this Patent, through the implementation of the refractory door lining in two separate layers, only connected by narrow bearing zones. Thus forming a large central chamber, virtually covering the whole space between the two layers. In this way, the gas pressure in the oven is completely discharged into this central chamber and no residual stress will cause the gas to escape. Furthermore, according to this Patent, the two layers are in different materials; since the temperature in the central chamber will reach almost the same value as in the oven, the outer layer in contact with the coking coal will be in material having high mechanical properties, such as for instance vibratory aluminous material, whereas the inner layer in contact with the door will be in material having excellent insulating characteristics, such as kaolin fiber based materials. This means that the total thickness of the refractory lining will be greatly reduced and the working volume of the coke oven increased. The weight of the refractory-door assembly is also profitably reduced. Furthermore, according to this Patent, the converging, inner surface of the refractory lining in touch with the coal is downward sloping so as to create a sloping coke wall which will prevent the coke from sliding down when the door is opened. This coke slide is a normal trouble which causes much loss of time to recover the coke and for cleaning up. It is a well known fact that the door edges have to be carafully scraped and cleaned each time the doors are opened, to remove deposits caused by caking and sintering of coal fines and condensate. Mechanical or manual scrapers are used for this purpose and this cleaning job is rather laborious and expensive. Accor­ ding to this Patent, these cleaning operations are no longer necessary since these products will no longer escape along the door edges. The fact that the protective door lining is consisting of two layers and that these layers are consisting of numerous, rather short-length, press formed elements greatly reduces the need for replacement of all or part of the lining. Further­ more, according to this Patent, replacement of either or both layers or of the complete element is very easy and fast since it is only necessary to loosen the anchor bolts of the refractory supporting structure. According to this Patent, the structure anchoring the refractory lining to the oven door is extremely simple and light-weight and it is consisting of properly assembled metal sections. The invention in question is illustrated in its practical implementation in the enclosed drawings, in which: Fig. 1 shows a frontal view of the face of a refractory element faced from inside the oven, mounted on a door section; Fig. 2 shows the K-K section of the assembly illustrated in Fig. 1; Fig. 3 shows a lateral view of the assembly illustrated in Fig. 1; Fig. 4, 5 and 6 show the sections X-X, Y-Y and Z-Z respectively of the assembly illustrated in Fig. 1; Fig. 7 shows a lateral view of a coke oven door obtained with the elements subject matter of this Patent; Fig. 8 shows an enlargement of the horizontal section of the refractory supporting structure at anchoring bolt level. With reference to the above illustrations, each refractory element is consisting of two layers 1, 2; layer 1 is resting on the inner door wall 3, while layer 2 is resting against the coking coal. A vast empty space 4 is created between the above two layers, communicating outwards with the bottom and ceiling of the coke oven and sideways with the door interstices (a 2 cm spacing is usually provided between the refractory 1, 2 of the door and the refractory 13 of the oven). Narrow zones for reciprocal support of the two layers 1, 2 are provided in the chamber 4, i.e. the lateral zones 5 and the central zones 6. The figures clearly show that the minimum gas passage in the chamber 4 is coinciding with section X-X of Fig. 1, as illustrated in Fig. 4, this zone being formed by two large circular openings, whereas central openings and large connections with the outside are provided in all other zones (sections Y-Y and Z-Z). This figure also shows that the external 6 and central 5 reciprocal bearing zones of the two layers are coinciding in the center of the refractory element whereas they are staggered at the top and bottom so as to create the peculiar configuration of the chamber 4 as shown in Fig. 3. It is obvious that the creation of the large central chamber 4 will cause the gas, especially the gas formed at the bottom and central zone of the coke oven, to escape upwards in the chamber until it reaches the zone above the coking coal from where it is tapped off, without residual pressure and without external losses and consequent fouling of the door edges. Each layer 1 and 2 being prefabricated, it is also clear that different materials may be used; in particular, layer 1 in contact with the door has an excellent insulation capacity and kaolin fiber may be used, for instance, for this purpose, whereas layer 2 in contact with coke is in material having an excellent mechanical strength, such as vibratory aluminous material. Therefore, the complete double-layer refractory lining will have a much longer life, smaller thickness and it will be much easier to handle because of its reduced weight. Maintenance and fettling of the refractory material will be cheaper since the smaller sized elements have a mechanical­ ly stronger outer layer and can be replaced at greater intervals, with the possibility to renew only one layer of the elements. The layer touching the door is in high insulating material which is obviously more expensive than conventional insulating and lagging materials, but it is well protected by the outer layer which, as said, has excellent mechanical strength. Fig. 7 shows that the internal lining of a door 3 is composed of various layered elements 1, 2 and that the top elements, especially their outer layer, have greater thickness than the underlying elements so as to create a downward sloping converging surface apt to form a sloping coke surface which will prevent its sliding down. The mounting structure or frame on which each double layer 1, 2 of the door lining is secured is consisting of two preferably box girder type section irons 7 along the longitudinal edges of the elements and interconnected by preferably channel shaped cross members located in the cen­ tral, reciprocally bearing zones of the two layers 1, 2. A shank 9, preferably in stainless steel with threaded end is fastened in the middle of these cross members 8, turned to the oven and passing through the holes in the bearing zone 6, projecting into a recess 10 where the shank 9 is secured by means of a nut and locknut 11 to assemble the two layers 1, 2, and secure them to the mounting frame. The recesses are then filled with removable insulating material. The reinforcing structure or frame of each element is secured to the door 3 by means of outwards pointing through bolts 12 anchored to the cross members 8, according to known techniques. The assembly of the supporting structure and the two lining layers 1, 2 is clearly illustrated in the Fig. 4, 5 and 6. This lining supporting structure, which is very simple and light-weight, requires minimum efforts to replace either or both layers 1, 2 and it is also very easy to replace a complete element or even the whole door lining.

Claims: 1. Internal refractory lining of coke oven doors, characterized by the fact that this lining is consisting in various short elements each obtained by two lining layers, one of which (1) touching the door (3) and the other (2) touching the coke, so as to create a vast empty space or chamber (4) only interrupted by narrow lateral (5) and central (6) zones on which the two layers (1, 2) are resting, the hollow space being in communication at the top, bottom and sides with the outside and receiving the coke oven gas from the lower and central oven zones, while conveying this gas, without any residual pressure and losses to the area located above the coal and including various mountings to secure the elements to the door (3) and the layers (1, 2) to each other, these mountings being formed by two lateral sections (7) inter­ connected by cross members (8) and fitted in the central zones (6) with a support on which the two layers are resting and with a central inwards pointing shanks (9) passing through the bearing zones (6), the shank (9) having a threaded end projecting in a recess (10) of the outerlayer (2) apt to receive a nut and lock nut (11) to fasten the two layers (1, 2) together and secure them onto the mounting which, in turn, is anchored onto the door (3) by means of through bolts (12). 2. Lining as described in Claim n° 1, characteri­ zed by the fact that each lining element and preferably its inner layer (2) in touch with the coke, has differing thickness values so as to create downward convergency to shape the coke wall with a slope which will prevent it from sliding down. 3. Lining as described in claim n° 1, characteri­ zed by the fact that the layers (1, 2) are in different materials, i.e. the layer (2) in touch with the coke is in material having high mechanical strength, as can be achieved with vibratory aluminous material, while the layer (1) touching the door has a high heat insulating capacity, as can be obtained with kaolin fiber. 4. Lining as described in claim n° 1, characteri­ zed by the fact that the recess (10) receiving the bolts (11) for reciprocal fastening of the layers (1, 2) while securing them to the mounting, are filled with removable insulating material. 5. Lining as described in claim n° 1, characteri­ zed by the fact that the zones (5, 6) on which the two layers (1, 2) are resting, are reciprocally offset, except for the central zone where the minimum cross section of the vertical gas passage is consisting of two large circular sections whereas this passage in other sections is greater and is connected to the also rather large lateral openings so that the vertical passages and lateral openings are forming the chamber (4) which virtually occupies the whole space between these layers.

Inventors: FABBRI, LUCIANO
Applicants: PREFIN S.R.L.
Application year: 1988
Main classification: C10B25
IPC codes: C10B25