A coke-oven door and a coke-oven battery having such a door

Abstract

 A coke-oven door for a coking chamber in coke-­oven battery has a door body (1) carrying a seal (3,15) and a door plug (4) consisting of a closed metal box construction. The side walls (11) of the plug (4) form, together with the side walls of the coke oven, wedge-­shaped gaps (12) which narrow in the direction of the door body. To reduce gas pressure on the seal (3,15) during coking

a) each gap (12) is formed by a front portion (10) of the side wall (11) of the box construction,

b) at a rear portion (14) of the box construction (4), near the door body, the side walls (11) recede from the walls of the coking chamber and form, in conjunction with the walls of the coking chamber, vertical gas flues (16) for coke-oven gas,

c) the gap (12) is so dimensioned that when the coking chamber is filled with coking coal and during coking, no or almost no coking coal can pass through the gap (12) into the gas flues (16).

Description

[0001] The invention relates to a coke-oven door for a coking chamber of a battery of coke-ovens, consisting of a door body carrying a door seal and a door plug which extends into the coking chamber, the door plug consisting of a generally closed metal box construction in which the side walls form, on each side of the plug when the door is closed, together with the side walls of the coking chamber, a gap which as seen in horizontal cross section has a long wedge shape narrowing in the direction towards the door body and opening towards the interior of the coking chamber.

[0002] A coke-oven door of this type is known from US-A-2993845. The door plug of this known coke-oven door, which is constructed as a metal box, solves the problem of graphite deposits on the surface of the conventional door plug made from refractory material. The door plug is closed which means that there is no or almost no transport of coke-oven gas through the inside of the door plug. Known metal door plugs have a tapered shape to facilitate putting the door into its closed position.

[0003] A problem with such a coke-oven door is that gas leakages occur through the door seal. These gas leakages are not acceptable from the viewpoint of environmental pollution. The first cause of gas leakages is the high pressure of coking gas during coking. High gas pressure occurs especially at the commencement of coking at the lowest part of the coke-oven door.

[0004] A second cause of gas leakages with the coke-­oven door described above is that the door plug is too inflexible along the length of the coke-oven door, so that the door body distorts and as a result leakages of gas arise through the door seal.

[0005] The object of the invention is to provide a coke-oven door of the type set out at the beginning, in which no or almost no gas leakages arise.

[0006] According to the invention the coke-oven door is characterised in that:

a) each long wedge-shaped gap is formed by a front portion of the side wall of the plug, being the portion which reaches furthest into the coking chamber,

b) at a rear portion of each side wall of the box construction, near the door body, the side wall is shaped to recede from the side wall of the coking chamber so as to form when the door is closed, together with the side wall of the coking chamber, a vertical gas flue for passage of coke-oven gas, so that gas pressure on the door seal during coking is reduced, and

c) the long wedge-shaped gaps are so dimensioned that when the coking chamber is filled with coking coal and during coking no or almost no coking coal can pass through the gaps into the gas flues.

[0007] The occurrence of gas leakages through the door seal is effectively reduced with the coke-oven door accoridng to the invention in that high gas pressures are prevented by the passage of coke-oven gas through the gas flues to the space above the coal in the coking chamber, from where the process gas is led off from the coking chamber through so-­called ascension pipes (standpipes).

[0008] For good operation according to the invention attention should be given to the shape and dimensions of the door plug.

[0009] Preferably therefore the gas flue formed by the side wall of the coking chamber and the rear portion of the side wall of the box oonstruction has a shape which, as seen in horizontal cross-section continuously and sharply widens in the direction towards the door body. By this, accumulations of coke-oven gas arriving at the door seal are avoided and the removal of coke oven gas from near the door seal is enhanced.

[0010] Preferably the front portion of the side wall of the plug as seen in horizontal section extends over 30 to 70% of the total thickness of the door plug from front to rear, and the smallest separation, when the door is closed, between the side walls of the door plug and the coking chamber is not less than 8 mm more preferably not less than 10 mm. If the front portion of the plug side walls has a length of less than 30% of the plug thickness, there are coal leakages; if this length is more than 70%, the gas flues are too small. If the length and dimensions of the wedge-shaped gap formed in this way are such that coking coal gets into the gas flues, fouling and blooking of the gas flues might occur; yet while the door is being fitted, there should be considerable play between the door plug and its side walls.

[0011] It is noted that WO-85/04180 discloses a coke-oven door with a closed metal plug in which the side walls are so shaped that gas flues are formed. This door plug has however a short rectangular gap on the front through which considerable leakage of coal takes place into the gas flues during the fitting of the door, or if the gap is so narrow that there is no coal leakage, difficulties arise when the door is fitted. It should be taken into account that whenever a coke-oven battery has been in service for some time, the width of the coking chambers varies one from another. As a result door plug constructions with narrow gaps cease to be interchangeable, and a door plug must be adapted to the width of the individual coking chamber.

[0012] The coke-oven door according to WO-85/04180 is further differentiated from the invention in that the door plug consists of two constructions along the direction of the coking chamber. The fastening of the two involves an internal assembly which can only be reached by widening the front wall of the door plug. The door plug design is complicated and is liable to thermal stresses.

[0013] DE-A-2,219,516 also discloses a coke-oven door in which vertical gas flues are formed adjacent the seal, but the whole of the door plug construction is not shown.

[0014] The use in the present invention of a closed box construction for the door plug, which encloses a substantial part of the space defined by the front face of the coking coal in the coking chamber, the side walls of the coking chamber and the door body, is essential. By this means the door body is well insulated, and heat loss from the coke-oven battery is reduced. At the same time the coking coal is evenly coked and there are no cold spots at the front face of the coal.

[0015] It is noted that EP-A-28679 shows a door plug consisting of a plate which is held away from the door body by stanchions. A similar door plug is also shown in DE-A-3440311, in which however the plate is fashioned as an open box for the transport of coke-oven gas, which is also held away from the door body by stanchions. In both cases the space behind the front plate is seen as a large gas flue. Both these designs of door plug have no long wedge-­shaped gap to preclude leakages of coking coal into the gas flue. A large gas flue of this type is favourable for precluding gas leakages through the door-sealing construction by the reduction of the pressure of the coke-oven gas by leading off the coke-oven gas, but it is not necessary because with the greatly improved effectiveness of present day sealing constructions brought about by environmental demands, smaller gas flues suffice, such as in this invention. Moreover in these prior art constructions, the coking process is unfavourably disturbed in that much more coke oven gas is led off through the large gas flue from the coking coal during coking in the coking chamber.

[0016] Preferably at least the upper end of the box construction of the plug is closed by a metal plate when the door is closed. The box construction is thus closed or nearly closed against transport of coke oven gas by shutting off at least its upper end. Passage of coke-oven gas through the interior of the box construction is undesirable, because the heat transfer to the coking coal during coking, especially to the coal near the door plug, can be disturbed. This can result in the coking of that coal being retarded, and not being done in time. Moreover, such gas transport leads very quickly to fouling of the interior of the box construction, which is difficult to clean. Preferably the lower end of the box construction is also closed by a metal plate. An additional advantage is that the lower end of the box construction is stiffened by the metal plate, reducing deformation of the box construction.

[0017] Preferably the box construction of the door plug is in the invention formed longitudinally (vertically) of a plurality of elements, each of which is connected to the door body. By this means the door plug is fully flexible along the length of the coke-oven door, so that distortion of the elements by thermal stresses brings no or almost no force to bear on the door body, and thus distortion of the door body is avoided.

[0018] Preferably in each pair of neighbouring elements of the box construction, when the door is closed, the lower element has a reduced cross-­section region at its upper end which is received in the lower end of the upper element. This telescopic or sleeve design frustrates any ingress of coal into the joint between the two elements. It appears that the sleeve design is durable and little susceptible to thermal stresses, because the elements can move unhindered in the longitudinal direction of the coke-oven door.

[0019] The upper and lower ends of the elements of the box construction are preferably closed by metal plates. By this, the elements can be hermetically sealed from the coking chamber, so that no gases and vapours can get into the interior of the elements via the joint between two elements and thus cannot give rise for instance to soiling of the insulation which is described below or to deterioration of the properties of this insulation.

[0020] Preferably, when the elements are closed, they are provided with ventilation means for the element interior. Preferably this ventilation means is a vent pipe, which is connected to the exterior air. An accompanying advantage of this is that measuring leads from measuring apparatus within the door plug can be led out through the vent pipe.

[0021] The metal plates which close the box construction are subject to thermal stresses and thus can be a source of cracks in the door plug. Therefore the number of metal plates used in a door plug is a matter that can only be optimised after experience over the long term.

[0022] Preferably the box construction of the plug has thermal insulating material arranged in its interior. Except when the insulating material is applied to the outside of the box construction, the insulating material need not be covered. In the case of hermetically sealed elements the insulating material cannot be fouled by tar products.

[0023] Preferably only the rear part of the box construction i.e. the part near the door body, is provided with insulating material. With this arrangement the coal near the door plug gets completely coked, while the door body is well insulated. Apparently good coking of the coal near the coke-oven door as described in the invention takes place by radiation in and around the door plug. For this reason the configuration and heat capacity of the door plug are of great importance.

[0024] Preferably the insulating material is refractory felt which is attached by fastening means to rear wall portions of the box construction. In this way the weight of the door plug is further reduced.

[0025] Embodiments of the invention will now be described by way of non-restrictive example with reference to the drawings, in which:

Figure 1 is a horizontal cross-section of a coke-oven door according to the invention during use,

Figure 2 is a vertical cross-section of the door plug of the coke-oven door of Fig. 1 on line II-II in Fig. 1,

Figure 3 shows the detail III in Fig. 2 on a larger scale,

Figure 4 is a horizontal cross section of the door plug on line IV-IV in Fig. 2,

Figure 5 is the detail V in Fig. 4, and

Figure 6 is a horizontal cross section of the door plug in a second embodiment of the invention.

[0026] The coke-oven door 1 shown in Fig. 1 consists of a door body 2 carrying a seal 3 on a membrane 15 and a door plug 4 which when the door is closed extends into the coal-filled coking chamber 5 of a battery of coke ovens 6. The door plug 4 is constructed as a metal box, with a thin wall 7, the interior of the box construction 8 being mainly hollow.

[0027] Fig. 2 shows that the box construction of the plug consists of a plurality of elements 9, arranged vertically one above another and each mounted on the door body 2.

[0028] Fig. 1 shows that the front portion 10 of each side wall 11 of the box construction when the door is closed forms a long narrow wedge-shaped gap 12 with the side walls 13 of the coking chamber 5, this gap 12 narrowing from the front corner towards the door body 2. The gap has at its narrowest place a width such that no or almost no leakage of coking coal from the coking chamber 5 past the narrowest place of the gap 12 can take place.

[0029] Moreover the rear portion 14 of each side wall 11 recedes from the coking chamber wall in the direction towards the door body 2 from the narrowest place of the gap 12, so that when the door is closed it forms, in conjunction with the side wall 13 of the coking chamber and with the door body 2 (i.e. with the membrane 15 of the seal 3 in the example illustrated), vertical gas flues 16 via which any high gas pressure arising during coking at the base of the door can be reduced. These flues 16 extend the whole height of the box construction and open at the top into the space above the coke.

[0030] The box construction 8 is closed, which means that no or almost no gas movement can take place through the hollow box construction during the coking process.

[0031] Fig. 3 shows that in each pair of neighbouring elements 9 the upper end of the lower element is provided with a reduced cross-section portion 21 which is at least partly received by the lower end 22 of the upper element, thus forming a sleeve or telescopic construction, which avoids excessive rigidity of the box construction.

[0032] In this embodiment, as is shown in Fig. 2, the upper and lower ends of the box construction are closed by metal plates 17. Alternatively or additionally both ends of each element 9 of the box construction are closed by metal plates 18 (see Fig. 3).

[0033] Fig. 4 shows that each closed element 9 is fitted with ventilation means for its interior, in the form of a vent pipe 18a, which in this embodiment leads to the outside air.

[0034] Each element is connected to the door body 2 by connecting elements 19. The embodiment of these connection elements shown in the figures, i.e. plugs threaded at the ends, is adapted to the embodiment of door body shown in the figures, especially the seal 3,15. It is within the scope of the expert in this field to choose connecting elements which are appropriate to the design of the door body. In addition Fig. 4 shows that the interior of the door plug is stiffened with a reinforcing beam 20.

[0035] Figs. 4 and 5 show that the box construction contains insulating material 23, arranged in the rear part of the construction nearest to the door body. In the example shown, refractory felt is used, attached to the rear wall 25 and to the rear parts 14 of the side walls 11 by appropriate fastening means 24.

[0036] A second embodiment for the door plug according to the invention is shown in Fig. 6, in which the part of the box construction consisting of the front wall 25a and the front portions 10 of the side wall 11 of the door plug is a separate hollow box construction which is attached by fastening means 27 to a metal brick holder 26 and to the door body (not shown). The metal brick holder forms a rear box construction and consists of a metal casing containing brick material and is filled with insulation material 23.

Claims

1. A coke-oven door for a coking chamber of a battery of coke ovens, consisting of a door body (1) carrying a door seal (3,15) and a door plug (4) which extends into the coking chamber when the door is closed, the door plug consisting of a generally closed metal box construction in which the side walls (11) form on each side of the plug (4), when the door is closed, together with the side walls of the coking chamber, a gap (12) which as seen in horizontal section has a long wedge-shape narrowing in the direction towards the door body and opening towards the interior of the coking chamber characterised in that

a) each said gap (12) is formed by a front portion (10) of the side wall (11) of the plug which portion reaches furthest into the coking chamber,

b) at a rear portion (14) of each side wall of the box construction, near the door body (1), the side wall is shaped to recede from the side wall of the coking chamber so as to form, when the door is closed, in conjunction with the side wall of the coking chamber, a vertical gas flue (16) for passage of coke-­ oven gas, so that gas pressure on the seal (3,15) during coking is reduced, and

c) the gaps (12) are so dimensioned that when the coking chamber is filled with coking coal and during coking, no or almost no coking coal can pass through the gaps into the gas flues (16).

2. A door according to claim 1 wherein each gas flue (16) has a shape which, as seen in horizontal cross-section continuously and sharply widens in the direction towards the door body.

3. A door according to claim 1 or claim 2 wherein the length in horizontal section, of the front portion (10) of the side walls of the box construction is from 30 to 70% of the total thickness from front to rear of the door plug.

4. A door according to any one of the preceding claims wherein the smallest separation between the side walls (11) of the door plug and the side walls of the coking chamber when the door is closed is not less than 8 mm.

5. A door according to any one of the preceding claims wherein when the door is closed at least the upper end of the box construction is closed by a metal plate (17).

6. A door according to any one of the preceding claims wherein the box construction of the plug (4) in the vertical direction of the door is formed from a plurality of elements (6), each connected to the door body (1).

7. A door according to claim 6 wherein in each pair of neighbouring box construction elements (6), the upper end of the lower element has a reduced cross-section region (21) which is received in the lower end (22) of the upper element.

8. A door according to claim 6 or claim 7 wherein the upper and lower ends of each element (6) are closed by metal plates (18).

9. A door according to any one of claims 6 to 8 wherein the elements (6) have means for ventilation of the interior of the element.

10. A door according to claim 9 wherein the ventilation means consists of at least one vent pipe which is openly connected to the exterior air.

11. A door according to any one of the preceding claims wherein in the interior of the box construction thermal insulating material (23) is arranged.

12. A door according to claim 11, wherein the insulating material (23) is located only at the rear part of the box construction nearest the door body (1).

13. A door according to claim 12 wherein the insulating material (23) is refractory felt which is attached by fastening means (24) to rear wall portions (24,25) of the box construction.

14. A coke-oven battery having a plurality of coking chambers and at least one coking chamber door according to any one of the preceding claims.

Drawing