EP2315975B1 - Fireproof wall, in particular for a combustion furnace - Google Patents

Description

The invention relates to a refractory wall with a boiler wall and a superior in distance from the boiler wall refractory and fire-proof 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 and 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 to temperatures of over 1000 ° C in today's incinerators and experience 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 material and / or design of the protective linings, so that the protective linings are not destroyed by greater 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 avoid that corrosive flue gases can pass through the protective cover and attack the boiler wall.

From the EP 1 032 790 B1 is a refractory wall of the generic type is known in which the plates of the protective cover have a tongue / groove structure or complementary stepped edges, so that even with thermally induced mutual displacements of the plates a certain tightness is maintained and at least a straight-line flow of flue gas is prevented. The mutual sealing of the individual plates is further increased by ceramic fiber strips, which are arranged between the individual plates in the region of the tongue and groove structures or the complementary stepped edges. In addition, the space between the pipe wall and the protective covering is encapsulated with a SiC flow concrete, which causes an additional seal between the plates and the pipe wall. On the other hand, however, there is a direct connection between the plates of the protective covering and the pipe wall, which reduces the flexibility of the wall system in terms of heat transfer requirements by this pouring of the intermediate space with flowing concrete. In addition, there is the danger that due to improper operation of the incinerator, for example by too fast raising or lowering of the same, the protective cover of the pipe wall or boiler wall generally dissolves.

From the DE 198 16 059 C2 a refractory wall is known having a tube wall and a spaced superior protective cover from a plurality of refractory plates, wherein the (non-cast) space between the tube wall and the protective cover is formed as at least one closed pressure chamber, wherein the or each pressure chamber with a pressurized inert gas is applied. 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, however, the heat transfer between the protective lining becomes due to the insulating effect of the protective gas and obstructs the pipe wall, so that depending on the application, not enough heat can be dissipated.
GB430021 describes a refractory wall according to the preamble of claim 1.

In view of the disadvantages of these known refractory wall systems, the invention has the object to improve a refractory wall of the generic type to the effect that on the one hand sufficient heat transfer between the protective panel and the boiler wall is guaranteed and that this heat transfer on the other hand can be selectively influenced quantitatively and locally.
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: A refractory wall, in particular for a combustion furnace, comprises a boiler wall and a refractory and fire-proof protective lining which is provided at a distance from the latter and protects the boiler wall against corrosion by flue gases. The protective cover comprises a plurality of juxtaposed and stacked refractory plates, which are fastened via at least one plate holder on the boiler wall. There is a space between the boiler wall and the protective lining. The refractory wall has means for supplying gas, in particular air, into the intermediate space. At least in a portion of the gap, there is disposed a particulate filler which has a porosity of 15-70% and which is coated with an activatable ceramic or mineral binder which exhibits its bonding effect when an activation temperature is exceeded. The refractory wall also has means for removing the gas from the space.
The particulate filling material between the boiler wall and the protective lining significantly improves the heat transfer from the protective lining to the boiler wall.

According to a preferred embodiment, the particulate filling material is arranged in zones of the wall or its interspace. In this case, individual zones may contain different particulate filler or may not be backfilled at all. Due to the zonal division and arrangement of the particulate filling material and by appropriate Choice of material, the heat transfer within the wall can be specifically controlled and thus optimally adapted to the operational requirements.

According to the invention, particulate filler having a porosity of 15-70% is used. In this way, the refractory wall according to the invention can advantageously be additionally developed as a ventilated system.

Fig. 1

- ein erstes Ausführungsbeispiel der erfindungsgemässen Wand in einer Ansicht auf die Schutzverkleidung,

Fig. 2

- einen Schnitt gemäss der Linie II-II in Fig. 1,

Fig. 3-4

- je einen Ausschnitt aus Fig. 2 in vergrösserter Darstellung,

Fig. 5

- eine Detailskizze analog Fig. 4 zur Erläuterung der Luftzuführung in die Wand,

Fig. 6

- eine schematische Skizze zur Erläuterung der Luftabführung aus der Wand,

Fig. 7

- eine schematische Skizze zur Anordnung von Luftzuführungsdüsen,

Fig. 8

- eine Schnittdarstellung analog Fig. 2 eines zweiten Ausführungsbeispiels der erfindungsgemässen Wand und

Fig. 9

- einen Schnitt durch ein Korn eines partikulären Füllmaterials.

In the following, the refractory wall according to the invention will be described in more detail with reference to the accompanying drawings with reference to two embodiments. Show it:

Fig. 1

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

Fig. 2

- A section according to the line II-II in Fig. 1 .

Fig. 3-4

- ever a section of Fig. 2 in an enlarged view,

Fig. 5

- a detailed sketch analog Fig. 4 to explain the air supply into the wall,

Fig. 6

a schematic sketch explaining the air discharge from the wall,

Fig. 7

a schematic sketch of the arrangement of air supply nozzles,

Fig. 8

- A sectional view analog Fig. 2 a second embodiment of the inventive wall and

Fig. 9

- A section through a grain of a particulate filler.

That in the Fig. 1-7 illustrated first embodiment of the refractory wall according to the invention comprises as a boiler wall a pipe wall 1 ( Figures 2-5 ) and a distance in front superior protective cover 2, wherein between the pipe wall 1 and the protective cover 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 made usually made of steel. The protective cover 2 comprises 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 having an SiC content of about 90% in the production, which are fire resistant up to over 1000 ° C. Each plate 21 is fastened to the tube wall 1 by, for example, four plate holders 22. The plate mounts are made of heat-resistant steel, eg steel no. 310 to AISI standard or material no. 1.4845 to DIN 17440. The plate mounts 22 essentially comprise in each case one bolt 22a welded to a web 12 and two nuts 22b and 22c seated on the bolt (Figures 3-5). The plate brackets 22 engage in vertical, inwardly widened slots 21a of the plates 21 and set the distance of the plates 21 to the tube wall. In the vertical direction of the protective cover 2, the plates 21 are movable to some extent, so as to allow thermally induced expansion or contraction movements. The plates 21 have, on their side facing the tube wall, the tubes 11 adapted cylindrical grooves, so that the clear width (gap width) of the gap 3 between the tube wall 1 and protective cover 2 over the entire wall is substantially approximately constant. Practical gap widths are 5-20 mm, preferably 5-10 mm. As far as the refractory wall substantially corresponds to the prior art, as for example by the document EP 1 032 790 B1 is given, and therefore needs no further explanation.

A first essential difference from the prior art is that the intermediate space 3 between the boiler wall, here the pipe wall 1, and the protective covering 2 is completely or partially filled with a particulate filling material (granulate) P. The particulate filler material P consists of ceramic or metallic materials, for example SiC, has a particle size of about 1-10 mm, preferably 3-7 mm, and according to the invention a porosity of about 15-70%. By the filling of the gap 3 with the particulate filler P, the heat transfer from the protective panel 2 to the boiler wall or here pipe wall 1 is increased by heat conduction. The increase depends on the selected material or its heat conduction properties and can be controlled within wide limits. Due to the open porosity of the particulate filler P can be additionally realize a ventilated wall system, which will be discussed in more detail below.

In practical operation of a combustion furnace, for example, due to the temperature profile in the furnace and the process engineering, the requirements for heat dissipation can vary locally. According to another important aspect of the invention can be taken into account by the fact that the refractory wall or the gap 3 between the protective panel 2 and the boiler wall, here the pipe wall 1, divided into different zones and divided and the individual zones in different way or with different particulate filler P or not backfilled at all. In this way, the heat transfer from the protective lining to the pipe wall can be optimally adapted locally to the operating requirements of the incinerator both quantitatively and zone by zone. In the Figures 1-4 For example, two such zones Z1 and Z2 are indicated purely by way of example. The zone classification depends on the operating requirements and can of course also be realized in the vertical direction. The spatial distribution of the gap 3 in individual zones can be done for example by separating plates 3a, as shown in the FIGS. 3 and 4 is indicated schematically.

According to the invention, the particulate filler material P is coated with a thin layer of a mineral or ceramic binder, as shown in FIG Fig. 9 is shown greatly enlarged. The actual filling material forms the core Pk, the surrounding, for example, about 100 μ thick coating or coating with the binder is denoted by Pb. As a binder, a material is used, which is activated only at high temperatures, for example above 100 ° C, ie unfolds its binding effect. As long as the particulate filler P is exposed to lower temperatures, the binder is not active and the particulate filler remains free-flowing. However, if, for example, the breakage of a plate 21 locally exceeds the activation temperature, the binder unfolds its adhesive or binding action and bakes the particulate filler together locally. This prevents trickling out of the breakage of the protective cover.

According to the invention, the refractory wall is additionally designed as a ventilated system. This means that the gap 3 between the protective panel 2 and the boiler wall, here the pipe wall 1, in the operation of a gas - usually air - flows through. Because of the open porosity of the particulate filling material P, the gas can also flow through the filling material. The gas (or the air) in the space is in operation under a pressure of about 2-50 mbar and has over the combustion chamber of the combustion furnace to about 2-10 mbar higher pressure. 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 gas into and out of the gap 3 of the wall, inlet nozzles 31 and outlet openings 32 are provided in the wall, the inlet nozzles 31 communicating with and communicating with one or more air supply channels or channels 33. these are fed ( Fig. 5 ). The gas or air supply takes place from the side of the boiler wall, wherein the inlet nozzles 31 pass through the boiler wall, in this case the pipe wall 1, in the region of its webs 12 ( Fig. 5 ). The outlet openings 32 pass through the protective cover 2, whereby the gas flowing through the gap 3 is discharged into the furnace chamber.

The inlet nozzles 31 are protected or arranged. By this is meant that it is ensured that the particulate filling material P can not get into the inlet nozzles and clog them. This can e.g. be achieved by a downward inclination of the inlet nozzles. Likewise, preferably, the outlet openings 32 should be protected so that the particulate filler P can not be blown through them.

The outlet openings 32 are preferably arranged in the region of the upper edge of the refractory wall, as shown in FIGS FIGS. 1 and 6 is indicated schematically. The inlet nozzles 31 can be arranged at the foot of the wall, ie near its lower edge, as shown in FIGS FIGS. 1 and 7 is shown. Preferably, however, the inlet nozzles 31 are distributed over the entire wall surface or individual areas thereof.

According to a further advantageous embodiment of the invention, the plates 21 of the protective cover 2 are mutually sealed in a double manner. As in particular from the FIGS. 3 and 4 it can be seen, 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 putty mass 23b. The felt strips 23a provide some flexibility but do not provide an absolute seal. The latter is achieved by the additional putty seal 23b.

As already mentioned, the boiler wall of the refractory wall according to the invention does not have to be designed as a tube wall, but can also be, for example, a normal metal wall. The Fig. 8 schematically shows a second embodiment in which the boiler wall is formed as such a flat metal wall 1a. Also in this embodiment causes the possibly zonal backing with particulate filler P the mentioned advantages.

Claims (11)

1. Refractory wall, in particular for a combustion furnace, with a boiler wall (1; 1a) and a refractory and fire-tight protective lining (2) placed in front of and spaced from the boiler wall for protecting the boiler wall from corrosion by smoke gas, the protective lining (2) comprising a multiplicity of refractory plates (21) arranged alongside and above one another, each fastened to the boiler wall with at least one plate mounting (22), an intermediate space (3) being provided between the boiler wall (1) and the protective lining (2) and a particulate filling (P) is arranged in at least one portion of the intermediate space (3), characterized in that the particulate filling (P) has a porosity of 15-70% and is coated with an activatable ceramic or mineral binding agent (Pb) that starts bonding or binding when an activation temperature is exceeded, and in that the refractory wall comprises means (31) for supplying gas, in particular air, to the intermediate space (3) and additionally means (32) for discharging gas from the intermediate space (3).
2. Wall according to claim 1, characterized in that the intermediate space (3) is subdivided into zones (Z1, Z2) along the area of the wall and that the particulate filling (P) is arranged in at least one zone (Z1).
3. Wall according to claim 2, characterized in that there are at least two zones (Z1, Z2) with differing particulate filling (P).
4. Wall according to any one of the preceding claims, characterized in that the particulate filling (P) has a grain size of 1-10 mm, preferably 3-7 mm.
5. Wall according to any one of the preceding claims, characterized in that the particulate filling (P) consists of ceramic or metallic materials, in particular SiC.
6. Wall according to any one of the preceding claims, characterized in that the clearance of the intermediate space (3) measures 5-20 mm, preferably 5-10 mm.
7. Wall according to any one of the preceding claims, characterized in that there are plate joints (23) between the refractory plates (21) that are sealed by inlaid refractory ceramic sealing strips (23a) and an additional luting compound (23b).
8. Wall according to any one of the preceding claims, characterized in that the means for supplying gas comprise protected inlet nozzles (31) that penetrate the boiler wall (1; 1a) and are designed and/or arranged such that they cannot be clogged by the particulate filling (P).
9. Wall according to claim 8, characterized in that the inlet nozzles (31) are arranged in the lower region of the wall or distributed over the wall surface.
10. Wall according to any one of the preceding claims, characterized in that the means for discharging gas comprise vent openings (32) that penetrate the protective lining (2) and are arranged in the uppermost region of the wall.
11. Wall according to any one of the preceding claims, characterized in that the boiler wall is a tube wall (1) consisting of tubes (11) connected by webs (12).

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