EP2326879A2

EP2326879A2 - Back-ventilated fire-resistant wall, in particular for a combustion furnace

Info

Publication number: EP2326879A2
Application number: EP09775765A
Authority: EP
Inventors: Andreas Kern; Karl-Ulrich Martin
Original assignee: Mokesys AG
Current assignee: Mokesys AG
Priority date: 2008-08-26
Filing date: 2009-08-21
Publication date: 2011-06-01
Anticipated expiration: 2029-08-21
Also published as: CH699406A2; ES2606727T3; DK2326879T3; PT2326879T; JP5530442B2; EP2326879B1; US20110146596A1; WO2010022523A2; PL2326879T3; JP2012500957A; WO2010022523A3

Abstract

A fire-resistant wall intended in particular for use in a combustion furnace comprises a tube wall (1), composed of tubes (11) connected by webs (12), and, placed in front at a distance from the tube wall, a fire-resistant protective cladding (2) composed of a plurality of fire-resistant panels (21) which are arranged next to and above one another and which are fastened to the webs (12) of the tube wall via in each case at least one panel holder (22). The panels (21) are provided with continuous open grooves (21a) into which the panel holders (22) engage. In the tube wall (1) are provided inlet openings (31) via which air can be introduced into the gap (3) between the tube wall (1) and the protective cladding (2). Also provided are outlet openings through which air can be removed from the wall. The air supply openings (31) are arranged in the region of the open grooves (21a) of the panels (21), with the result that the supplied air flows directly into the grooves and is distributed through these grooves over the entire wall. By incorporating the grooves (21a) into the air distribution system within the wall, the gap width (d) between the tube wall (1) and the protective cladding (2) can be reduced to £ 5 mm, thereby considerably improving the heat transfer. It is possible at the same time to manage with relatively small air volumes and the pressure loss is considerably reduced, making it possible to achieve considerable energy savings.

Description

Ventilated fireproof wall, in particular for a combustion furnace

The invention relates to a ventilated fire-resistant wall with a boiler wall and a superior distance from the boiler wall refractory protective cover according to the preamble of claim 1.

Such refractory walls are e.g. used in combustion chambers of combustion plants. The boiler wall is often designed as a metal pipe wall and is usually made of webs connected by pipes. The fire-resistant protective cover, which is suspended at a distance from the pipe wall, is intended to protect the pipe wall from corrosion by flue gases. Refractory walls are e.g. also used in fluidized bed ovens, where the boiler wall consists of a more or less thick simple metal wall. Again, the boiler wall or metal wall to be protected from corrosion.

The boiler walls and protective coverings are often exposed in today's incinerators temperatures of over 1000 ⁰ C and learn even with a suitable choice of material due to the large temperature differences of the individual operating conditions strains and contractions. The differences in temperature are generally greater for the protective linings than for the boiler walls themselves, which must be taken into account in the choice of materials and / or design of the protective linings, so that the protective linings are not destroyed by larger strains and contractions than the boiler walls. The protective panels or the plates thereof are therefore usually not rigidly attached to the boiler walls but with play, so that compensating movements parallel to the boiler walls are possible to a limited extent.

The choice of a suitable material for the protective covering makes it possible for the protective covering to be matched to the boiler wall for every operating condition. For boiler walls made of steel, protective linings made of ceramic materials, in particular SiC, have proven successful, although the SiC content can be very different. In practice, SiC masses or SiC plates with a SiC content of 30% -90% are used. The panels of the protective cover are usually mutually sealed by various measures to some extent to prevent the passage of flue gases. However, in practice this alone can not completely prevent corrosive flue gases from passing through the protective lining and attacking the boiler wall.

So-called ventilated wall systems counteract this problem by pumping through a protective gas - generally air - through the space between the boiler wall and the protective cover. The gas or air is in this case with respect to the combustion chamber under a slight overpressure, which prevents the flue gases from penetrating from the combustion chamber into the wall space and can attack the boiler wall or other metal parts. Conventional wall systems of this type have a relatively high air requirement and require an undesirably high pump power.

From DE 198 16 059 C2 a ventilated refractory wall with a pipe wall and a distance superior protective cover of a plurality of refractory plates is known in which the space between the pipe wall and the protective cover is formed as at least one closed pressure chamber, wherein the or Each pressure chamber is acted upon by a protective gas under overpressure. The excess pressure of the protective gas is so high that no flue gas can penetrate through the protective lining from the combustion furnace. As a result, although a relatively good corrosion protection effect is achieved, but by the insulating effect of the protective gas, the heat transfer between the

Protective cover and the pipe wall obstructed, so that depending on the application, not enough heat can be dissipated.

The invention has for its object to improve a refractory wall of the generic type such that on the one hand the boiler wall is reliably protected from corrosion by flue gases and that on the other hand, a process-optimized heat transfer between the protective panel and the boiler wall is guaranteed and the protective gas pumping power is minimized. This object is achieved by the inventive refractory wall, as defined in independent claim 1. Particularly advantageous developments and refinements of the invention will become apparent from the dependent claims.

The essence of the invention consists in the following: The refractory wall is designed as a ventilated system and comprises gas supply means for supplying a protective gas, usually air, into the space between the boiler wall and the protective covering. The protective gas flowing through the wall prevents the penetration of flue gases into the wall. The supply of the gas or the air takes place through the boiler wall in the region of the vertical through grooves present in the plates, via which the gas or the air can be distributed over the entire wall with the lowest pressure drop. As a result, the distance between the boiler wall and the protective covering can be reduced to a few millimeters, and it is possible to manage with relatively small volumes of inert gas or air, which in turn has the advantage that only a little additional waste gas is produced. Due to the small distance between boiler wall and protective cover, the heat transfer is significantly increased. The low pressure drop in the grooves results in a considerable energy saving.

Preferably, the grooves of adjacent superimposed plates are aligned and in communicative connection.

The gas supply means advantageously comprise inlet openings which are arranged in the region of the grooves in the boiler wall. The inlet openings are preferably arranged distributed in the lower region of the boiler wall or over the boiler wall surface.

According to a preferred exemplary embodiment, the boiler wall is a pipe wall made of pipes connected by webs and the inlet openings are arranged in the region of the webs. The gap width of the intermediate space is advantageously <5 mm, preferably <3 mm.

Advantageously, the wall has means for removing the protective gas from the intermediate space and the grooves. The means for removing the protective gas advantageously have the protective covering or the boiler wall by cross-outlet openings, which are preferably arranged in the uppermost region of the wall.

According to a preferred embodiment, there are plate joints between the refractory plates, which are sealed by inserted ceramic sealing strips made of refractory material and by an additional putty.

The outlet openings are advantageously formed by non-sealed areas of the plate joints.

Advantageously, the plate holders each comprise a wall mounted on the boiler, preferably welded, threaded pin and a flat plate support surface and a screw screwed into the bolt, with the distance of the held plate can be varied from the boiler wall.

According to an advantageous embodiment, the plates are arranged at least one horizontal row of plates relative to the other plates at a greater distance from the vessel wall and thereby form a transverse channel through which protective gas, in particular air, can spread over the wall width.

According to a preferred embodiment, at least some laterally adjacent plates are provided with a continuous, substantially horizontally extending transverse channel, which connects the vertical grooves of these plates with each other in a communicative manner. In this case, the plates provided with the transverse channel are advantageously arranged above or below wall installations and / or in spaced-apart plate rows. According to a further advantageous embodiment, the plates are provided with Verwirbe- elements which generate in the flowing between the plates and the boiler wall inert gas vortices and thereby increase the heat transfer between the plates and the boiler wall. The swirling elements are advantageously formed by raised and / or recessed areas of the plates, which face the boiler wall.

The protective gas or the discharged air removed from the refractory wall is preferably returned to the refractory wall and / or fed into the incinerator as primary gas or air and / or secondary gas or air.

In the following, the refractory wall according to the invention will be described in more detail with reference to the attached drawings by means of exemplary embodiments. Show it:

1 shows a first embodiment of the inventive wall in a view of the protective covering,

2 shows a section along the line II-II in Fig. 1,

3 shows a section along the line III-III in Fig. 1,

4 is a detail of FIG. 3 in an enlarged view,

5 shows a view similar to FIG. 1 of a variant of the wall,

6 is a perspective oblique view of a specially designed plate of the protective cover,

7 shows a sectional view analogous to FIG. 3 of a second exemplary embodiment of the wall according to the invention, FIG. 8 shows a schematic view of a combustion plant with a refractory wall according to the invention,

9 shows an oblique perspective view similar to FIG. 6 of an embodiment variant of a panel of the protective covering, FIG.

10 is a view of the plate in the direction of arrow X of FIG. 9,

11 shows a section through the plate along the line XI-XI of Fig. 10 and

12 shows a section through the plate along the line XII-XII of FIG. 10.

The position and direction designations used below, such as top, bottom, width, height, vertical, horizontal, transverse, one above the other, side by side, etc. refer to the usual orientation of the wall in practical use.

The first exemplary embodiment of the wall of the invention, which is designated as a whole by W, comprises a pipe wall 1 (FIGS. 2-4) and a protective covering 2 spaced apart from it, wherein between the pipe wall 1 and the protective lining 2 a gap 3 is formed. The pipe wall 1 consists of a plurality of vertical use in practice pipes 11, which are held together by webs 12 at a mutual distance. The tubes 11 and the webs 12 are usually made of steel. The protective covering 2 consists of a plurality of juxtaposed and superimposed refractory plates 21, which interlock, for example, by complementary shaping of their edges and in this way are mutually sealed to a certain extent. The joints between the plates 21 are denoted by 23. The plates are, for example, ceramic SiC plates, preferably SiC 90 plates with an SiC content of about 90% in the manufacture, which are fire-resistant up to more than 1000 ° C. Each plate 21 is fastened to the tube wall 1 by means of, for example, four plate holders 22. The plate mounts are made of heat-resistant steel, eg steel no. 310 according to ANSI standard or material no. 1.4845 according to DIN 17440. The plate mounts 22 essentially comprise one NEN on a web 12 welded square bolt 22a with internal thread and flattened side surfaces 22b and a screwed into the square bolt 22a screw 22c (Fig. 4). The plate holders 22 engage in continuous vertical, inwardly expanded open grooves 21a of the plates 21 and set the distance of the plates 21 to the tube wall. In the vertical direction of the protective covering 2, the plates 21 are to some extent movable, so as to allow thermally induced expansion or contraction movements. The plates 21 are on their side facing the tube wall, the tubes 11 form adapted (cylindrical grooves 21 c, Fig. 6), so that the clear width or gap width d of the gap 3 between the pipe wall 1 and the protective covering 2 over the entire wall substantially approximately is constant.

The plates 21 of the protective cover 2 are preferably mutually sealed in a double manner. As can be seen in particular from FIGS. 3 and 7, the z-shaped plate joints 23 of the protective covering 2 are sealed by inserted ceramic sealing strips 23a of refractory material and by an additional cement compound 23b. The ceramic sealing strips 23a impart some flexibility but do not provide an absolute seal. The latter is achieved by the additional putty seal 23b.

The refractory wall W is designed as a ventilated system. This means that the gap 3 between the protective covering 2 and the boiler wall, in the first embodiment of the tube wall 1, during operation of a protective gas - usually air - flows through. The gas (or the air) in the intermediate space has a slight overpressure relative to the combustion chamber of the combustion furnace. This prevents corrosive flue gases from leaking through the protective covering from the combustion chamber into the intermediate space 3 and can attack the pipe wall 1.

For the introduction and discharge of the protective gas into and out of the gap 3 of the wall, inlet openings 31 and outlet openings 32 are provided in the wall, the inlet openings 31 communicating with and communicating with one or more supply channels or channels 33. they are fed the (Figures 2 and 3). The protective gas or air is supplied from the side of the boiler wall, wherein the inlet openings 31 pass through the boiler wall, here the pipe wall I ₅ in the region of the webs 12 (Figures 3 and 4). The outlet openings 32 (FIG. 1) pass through the protective covering 2, as a result of which the protective gas flowing through the intermediate space 3 is discharged into the boiler.

Alternatively, instead of the protective cover 2, the outlet openings can be arranged in the boiler wall, in particular in webs 12 of the pipe wall 1, and the protective gas can be discharged to the outside (similar to FIG. 4, but instead of the inlet opening 31 shown there, a corresponding outlet opening and with) reverse inert gas flow direction). The protective gas discharged to the outside is preferably sucked into a comb box 33a (FIG. 8) arranged on the outside of the boiler wall, in which a negative pressure is built up for this purpose. In this way, the amount of exhaust gas in the boiler is not unnecessarily increased by inert gas, so that the emission control system is not charged additionally. In addition, the shielding gas discharged to the outside can be analyzed for harmful substances if necessary.

FIG. 8 shows how the refractory wall W according to the invention is inserted into an incinerator. The incinerator designated as a whole by 100 comprises, in a manner known per se, a material entry space 110 and a combustion chamber 120. The refractory wall W is arranged in the region of the combustion chamber 120 and forms part of its wall. The supply of protective gas or air takes place in the lower region of the wall W via the aforementioned comb box 33. In the upper wall region, the further comb box or collecting channel 33a is arranged, via which the protective gas or the air is again removed from the refractory wall W. , The discharged protective gas or the discharged air can either be fed back into the refractory wall W via the lower comb box 33 (arrow 113) or fed to the incinerator 100. The feed into the incinerator can take place in the entry space 110 as a primary gas or air (arrow 111) and / or at the lower end of the combustion chamber 120 as a secondary gas or air (arrow 112). The outlet openings 32 are preferably arranged in the region of the upper edge of the refractory wall, as is indicated schematically in FIG. 1. The outlet ports 32 may be formed by unsealed portions of the plate joints 23 or alternatively, as discussed above, through openings in the lands 12 of the tube wall 1. The inlet ports 31 may be located at the foot of the wall, ie near its lower edge this is shown in Fig. 2. However, the inlet openings 31 may also be distributed over the entire wall surface or individual areas thereof.

An essential aspect of the invention is that the feed of the

Protective gas or the air directly in the region of the continuous open grooves 21a of the plates 21 takes place, as can be seen in particular from Figures 3 and 4. In Fig. 4, the supplied air is symbolized by the arrow L. The inlet openings 31 are arranged in the webs 12 in the region of the open grooves 21a. The supplied gas or the air passes primarily directly into the open grooves 21a and can be distributed over the entire wall via these as a result of their relatively large cross section without great flow resistance. This allows to greatly reduce the gap 3 between the boiler wall or here the pipe wall 1 and the curtain guard 2, wherein the gap width d (Fig. 4) in practice only 1-5 mm, preferably 1-3 mm. The tube wall 1, the plates 21 harmless contact also in places. By exploiting the grooves 21 a as inert gas or air distribution channels within the wall and the reduced clear distance d between the pipe wall 1 and protective cover 2 can with less Gasbzw. Air volumes are getting along and there are extremely low pressure losses. The required pressure over the internal pressure of the tank can be reduced to 1-10 mbar, preferably even 1-5 mbar. This in turn leads to significant energy savings in practical operation. In addition, the smaller distance between the pipe wall and the protective cover considerably increases the heat transfer.

A further improvement of the protective gas or air distribution within the wall can be achieved according to an advantageous development of the invention in that horizontal plate rows of the protective lining in certain vertical distances which, for example, each 2-4 m, are arranged at a slightly greater distance from the pipe wall than the other plates, so that horizontal transverse channels are formed over which the air can spread over the wall width.

Additionally or alternatively, according to a particularly advantageous further

Embodiment of the invention even in the or some plates themselves be formed substantially horizontally extending transverse channels, as illustrated in Figures 5 and 6. This is particularly important when the wall is in use inserts, e.g. a burner or a window, which interrupt the vertical grooves locally, so that over or in an alternative embodiment - when supplying protective gas or air from above - below the internals lying wall parts are not directly supplied with inert gas or air can. 5 shows a section of a wall with a built-in 40. It can be seen that the grooves 21a are interrupted in the region of the built-40. In order to be able to supply also the wall parts or plates 21 lying above the built-in parts 40, the plates 21 of the plate row immediately above the insert are provided with transverse channels 21b, which connect the vertical grooves 21a of the plates 21 of the plate row in a communicating manner. In this way, protective gas or air from the laterally adjacent, uninterrupted grooves 21a can flow transversely into the grooves 21a of the plates 21 lying above the insert 40, as illustrated in FIG. 5 by the flow arrows, not designated.

Fig. 6 shows a plate 21 in which a transverse channel 21b is formed. As can be seen, the transverse channel 21b is open on both sides of the plate 21, so that the transverse channels of adjacent plates form a continuous flow path.

The transverse channels 21b do not have to extend through the entire plate row lying above the built-in 40. In practice, it is sufficient if the plates lying above the built-in plates are connected in a communicating manner at least on one side, but preferably on both sides, with at least one adjacent plate of the row of plates lying laterally outside the fitting. Even if the vertical flow of inert gas or air is interrupted by no internals, it may be in the interests of better Flow distribution be advantageous to arrange at intervals plate rows with transverse channels or even equip all plates with transverse channels.

According to another important aspect of the invention, the heat transfer between the plates of the protective covering 2 and the tube wall 1 can be increased by arranging swirling elements in the flow path of the protective gas or the air, as shown purely for example in FIGS. 9-12 is.

In one embodiment, the swirling elements may be formed by raised arcuate ribs 21 d in the region of the cylindrical grooves 21 c of the plates 21. Alternatively or additionally, the turbulence elements can also be formed by recesses 21 e in the region of the flow paths of the protective gas or the air. Finally, the swirling elements may also comprise peg-like elements 21 f, which project into the open grooves 21 a.

The protective gas or air supply, as already mentioned, via one or more supply channels 33, which are preferably designed as a comb box. The blower required for the passage of the air is driven, for example, by a frequency-controlled motor, wherein the overpressure in the grooves 21a is measured at one or more points and used to control the blower. In this way, the energy requirement can be optimized or minimized.

As already mentioned, the boiler wall of the inventive fireproof wall does not have to be designed as a tube wall, but may for example also be a normal metal wall. Fig. 7 shows schematically a second embodiment in which the boiler wall is formed as such a flat metal wall 1 '. Also in this embodiment, the feeding of the air into the grooves 21a of the plates 21 and the resulting reduction in the gap width of the intermediate space 3 causes the mentioned advantages.

Claims

claims

1. Ventilated refractory wall, in particular for a combustion furnace, with a boiler wall (1, 1 ') and a distance from this superior fireproof protective covering (2) of a plurality of juxtaposed and superimposed refractory plates (21) above each at least one plate holder (22) is attached to the boiler wall (1, 1 ') so that at least part of a space (3) is present between the boiler wall (1, 1') and the protective lining (2), and with gas supply means (31 ) for the supply of protective gas, in particular air, in the intermediate space (3) between the boiler wall (1, 1 ') and the protective covering (2), characterized in that the plates (21) substantially vertically extending through, to the boiler wall (1 1 ') and in the interior of the plates (21) have an expanded cross-section grooves (21a), in which the plate holders (22) engage, and that the gas supply means (31) the inert gas in the Grooves (21a) and / or in the region of the grooves (21a) out in the ^'gap (3).

2. Wall according to claim 1, characterized in that the grooves (21a) of adjacent superimposed plates (21) are aligned and in a communicating compound düng.

3. Wall according to one of the preceding claims, characterized in that the gas supply means comprise inlet openings (31) which are arranged in the region of the grooves (21a) in the boiler wall (1, 1 ').

4. Wall according to claim 3, characterized in that the inlet openings (31) are arranged distributed in the lower region of the boiler wall (1, 1 ') or over the boiler wall surface.

5. Wall according to one of the preceding claims, characterized in that the boiler wall is a pipe wall (1) by webs (12) connected to tubes (11) - and that the inlet openings (31) in the region of the webs (12) are arranged.

6. Wall according to one of the preceding claims, characterized in that the gap width (d) of the intermediate space (3) <5 mm, preferably <3 mm.

7. Wall according to one of the preceding claims, characterized in that it comprises means (32) for discharging the protective gas from the intermediate space (3) and the

Has grooves (21a).

8. Wall according to claim 7, characterized in that the means for discharging the protective gas, the protective covering (2) or the boiler wall (1, 1 ') through-de outlet openings (32), which are preferably arranged in the uppermost region of the wall.

9. Wall according to one of the preceding claims, characterized in that between the refractory plates (21) plate joints (23) are present, which are sealed by inserted ceramic sealing strips (23 a) of refractory material and by an additional cement compound (23 b).

10. Wall according to one of the preceding claims, characterized in that the plate holders (22) each have a wall (1, 1 ') attached, preferably welded, bolts (22a) with internal thread and a flat plate support surface ( 22b) and in the bolt (22 a) screwed screw (22 c) comprise, with which the distance of the held plate (21) of the boiler wall (1, 1 ') can be varied.

11. Wall according to one of the preceding claims, characterized in that the plates (21) of at least one horizontal row of plates are arranged opposite the other plates (21) at an approximately greater distance from the vessel wall (1, 1 ') and thereby form a transverse channel, by the protective gas, in particular air, can distribute over the wall width.

12. Wall according to one of the preceding claims, characterized in that at least some laterally adjacent plates (21) are provided with a continuous, substantially horizontally extending transverse channel (21b), which the vertical kalen grooves (21 a) of these plates (21) connects communicating with each other.

13. Wall according to claim 12, characterized in that the with the transverse channel (21b) equipped plates (21) above or below wall installations (40) are arranged.

14. Wall according to claim 12 or 13, characterized in that the with the transverse channel (21b) equipped plates (21) are arranged in spaced superimposed plate rows.

15. Wall according to one of the preceding claims, characterized in that it provides with swirling elements (2 Id; 2 Ie; 2If) for the in the space (3) between the boiler wall (1; 1 ') and the protective cover (2) flowing protective gas is.