DK2326879T3

DK2326879T3 - Rear vented refractory wall, especially for an incinerator

Info

Publication number: DK2326879T3
Application number: DK09775765.2T
Authority: DK
Inventors: Andreas Kern; Karl-Ulrich Martin
Original assignee: Mokesys Ag
Priority date: 2008-08-26
Filing date: 2009-08-21
Publication date: 2017-01-16
Also published as: JP5530442B2; CH699406A2; EP2326879B1; PL2326879T3; EP2326879A2; WO2010022523A3; ES2606727T3; WO2010022523A2; US20110146596A1; JP2012500957A; PT2326879T

Description

Back-ventilated refractory wall, in particular for an incinerator

The invention relates to a back-ventilated refractory wall with a boiler wall and a refractory protective lining put in front of and spaced from the boiler wall according to the preamble of Claim 1.

Such refractory walls are used for instance in fire chambers of incinerating plants. Frequently the boiler wall is designed as metal tube wall and as a rule consists of tubes connected by webs. The refractory protective lining suspended in front of and spaced from the tube wall is to protect the tube wall from corrosion through smoke gasses. Refractory walls are for instance also used with fluidized bed furnaces, wherein the boiler wall consists of a simple metal wall of greater or lesser thickness. Here, too, the boiler wall or metal wall is to be protected from corrosion.

The boiler walls and protective linings in today's incinerating plants are often exposed to temperatures of more than 1000°C and are subjected to expansions and contractions because of the large temperature differentials of the individual operating states even with suitable choice of material. Temperature differentials are generally greater with the protective linings than with the boiler walls proper, which has to be considered when selecting the material and/or designing the protective linings, so that the protective linings are not destroyed through expansions and contractions greater than the boiler walls. As a rule, the protective linings or the tiles of these are therefore not rigidly attached to the boiler wall but with play, so that offsetting movements parallel to the boiler walls are possible to a limited extent.

The selection of a suitable material for the protective lining makes possible that the protective lining is matched to the boiler wall for any operating state. For boiler walls of steel, protective linings of ceramic materials, in particular SiC, have proved suitable, while the SiC content can vary greatly. In practice, SiC compounds or SiC tiles with SiC content of 30%-90% are employed.

The tiles of the protective lining are generally sealed against one another to a certain degree through various measures in order to prevent the passage of smoke gasses. In practice, however, this can not entirely prevent that corrosive smoke gasses can penetrate the protective lining and attack the boiler wall.

So-called back-ventilated wall systems combat this problem in that a protective gas -generally air - is pumped through the intermediate space between the boiler wall and the protective lining put in front. The gas or the air is subjected to slight overpressure relative to the fire chamber as a result of which it is prevented that the smoke gasses from the fire chamber can enter the wall intermediate space and attack the boiler wall or other metal parts. Conventional wall systems of this type have a relatively large air requirement and require an undesirably high pumping rate.

From DE 198 16 059 C2 a back-ventilated refractory wall with a tube wall and a spaced protective lining of a multiplicity of refractory tiles put in front is known, wherein the intermediate space between the tube wall and the protective lining is designed as at least one closed pressure chamber, wherein the or each pressure chamber is charged with pressurized protective gas. The overpressure of the protective gas is so great that no smoke gas from the incinerator can enter through the protective lining. Although a relatively good corrosion protection effect is achieved by this, the insulating effect of the protective gas hinders the heat transfer between the protective lining and the tube wall, so that depending on the use not sufficient heat can be removed. A back-ventilated refractory wall with the features of the preamble of Claim 1 is known from DE 9016206 U1.

The invention is based on the object of improving a refractory wall of the generic type in that the boiler wall on the one hand is reliably protected from corrosion through smoke gasses and that on the other hand a process-optimized heat transfer between the protective lining and the boiler wall is guaranteed and the protective gas pumping rate minimized.

This object is solved through the refractory wall according to the invention, as defined in the independent Claim 1. Particularly advantageous further developments and configurations of the invention are obtained from the dependent claims.

The essence of the invention is the following: The refractory wall is designed as back-ventilated system and comprises gas feeding means for feeding a protective gas, generally air, into the intermediate space between the boiler wall and the protective lining. Through the protective gas flowing through the wall the entry of smoke gasses in the wall is prevented. The gas or the air is fed through the boiler wall in the region of the continuous vertical grooves present in the tiles via which the gas or the air can spread over the entire wall with minimal pressure drop. Because of this, the spacing between boiler wall and protective lining can be reduced to a few millimetres and relatively small protective gas or air volumes are sufficient, which in turn has the advantage that little additional waste gas is produced. Through the small spacing between boiler wall and protective lining the heat transfer is substantially increased. The low pressure drop in the grooves results in considerable energy saving.

Preferentially, the grooves of neighbouring tiles located on top of one another are in alignment and connected in a communicating manner.

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

According to a preferred exemplary embodiment the boiler wall is a tube wall of tubes connected by webs and the inlet openings are arranged in the region of the webs.

The gap width of the intermediate space is advantageously < 5mm, preferentially < 3mm.

Advantageously, the wall has means for discharging the protective gas from the intermediate space and the grooves. The means for discharging the protective gas advantageously comprise outlet openings penetrating the protective lining or the boiler wall which are preferentially arranged in the uppermost region of the wall.

According to a preferred exemplary embodiment tile joints are present between the refractory tiles which are sealed through inserted ceramic sealing strips of refractory material and through an additional grout.

The outlet openings are advantageously formed by regions of the tile joints that have not been sealed.

Advantageously the tile mountings each comprise a bolt fastened to the boiler wall, preferentially welded on, with internal thread and a flat tile contact surface, and a screw screwed into the bolt with which the spacing of the held tile from the boiler wall can be varied.

According to an advantageous embodiment the tiles of at least one horizontal tile row are arranged at a slightly greater spacing from the boiler wall relative to the remaining tiles and consequently 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 neighbouring tiles are provided with a continuous transverse channel substantially running horizontally, which joins the vertical grooves of these tiles with one another in a communicating manner. Here, the tiles equipped with the transverse channel are arranged above or below wall installations and/or in tile rows located spaced on top of one another.

According to a further advantageous embodiment the tiles are provided with swirling elements, which generate vortices in the protective gas flowing between the tiles and the boiler wall and because of this increase the heat transfer between the tiles and the boiler wall. The swirling elements are advantageously formed through raised and/or sunk regions of the tiles facing the boiler wall.

The protective gas or the air discharged from the refractory wall is preferentially returned into the refractory wall and/or fed into the incinerating plant as primary gas or air and/or secondary gas or air.

In the following, the refractory wall according to the invention is described in more detail by means of exemplary embodiments making reference to the enclosed drawings. It shows:

Fig. 1 - a first exemplary embodiment of the wall according to the invention in a view onto the protective lining,

Fig. 2 - a section according to the line ll-ll in Fig.1,

Fig. 3 - a section according to the line Ill-Ill in Fig. 1,

Fig. 4 - a detail from Fig. 3 in enlarged representation,

Fig. 5 - a view similar to Fig. 1 of a version of the wall,

Fig. 6 - a perspective oblique view of a specially designed tile of the protective lining,

Fig. 7 - a sectional representation similar to Fig. 3 of a second exemplary embodiment of the wall according to the invention,

Fig. 8 - a schematic view of an incinerating plant with a refractory wall according to the invention,

Fig. 9 - a perspective oblique view similar to Fig. 6 of an embodiment version of a tile of the protective lining,

Fig. 10 - a view of the tile in the direction of the arrow X of Fig.9,

Fig. 11 - a section through the tile according to the line XI-XI of Fig. 10 and

Fig. 12 - a section through the tile according to the line XII-XII of Fig. 10.

The position and directional designations such as top, bottom, width, height, vertical, horizontal, transverse, on top of one another, next to one another etc. used in the following refer to the usual orientation of the wall in practice.

The first exemplary embodiment of the refractory wall according to the invention designated W as a whole shown as detailed in Fig. 1-4 comprises a tube wall 1 (Figures 2-4) as boiler wall and a protective lining 2 put in front of and spaced from said tube wall, wherein between the tube wall 1 and the protective lining 2 an intermediate space 3 is formed. The tube wall 1 consists of a multiplicity of in practical use vertical tubes 11, which are held together mutually spaced by webs 12. The tubes 11 and the webs 12 commonly consist of steel. The protective lining 2 consists of a multiplicity of refractory tiles 21 arranged next to one another and on top of one another, which engage in one another through complementary shaping of their edges and in this manner are mutually sealed to a certain degree. The separating joints between the tiles 21 are designated 23. The tiles for example are ceramic SiC tiles, preferentially SiC 90 tiles with a SiC content of approximately 90% in production, which are fire-resistant to above 1000°C. Each tile 21 is fastened to the tube wall 1 by means of for example four tile mountings 22. The tile mountings consist of heat-resistant steel e.g. steel number 310 according to AISI standard or material number 1.4845 according to DIN 17440.

The tile mountings 22 substantially comprise a square bolt 22a welded to a web 12 with internal thread and flattened lateral surfaces 22b and a screw 22c (Fig.4) screwed into the squared bolt 22a. The tile mountings 22 engage in continuous vertical, open grooves 22a widened towards the inside of the tiles 21 and determine the spacing of the tiles 21 from the tube wall. In vertical direction of the protective lining 2 the tiles 21 are movable to a certain degree so as to allow thermally-related expansion or contraction movements. On their side facing the tube wall the tiles 21 are adapted in shape to the tubes 11 (cylindrical channels 21c, Fig. 6) so that the clear width or gap width d of the intermediate space 3 between tube wall 1 and protective lining 2 is substantially roughly constant over the entire wall.

Preferentially, the tiles 21 of the protective lining 2 are mutually sealed in two ways. As is in particular evident from Figures 3 and 7, the tile joints 23 of the protective lining 2 designed z-shaped are sealed through inserted ceramic sealing strips 23a of refractory material and through an additional grout 23b. The ceramic sealing strips 23a provide a certain flexibility, but do not provide absolute sealing. The latter is achieved through the additional grout sealing 23b.

The refractory wall W is designed as back-ventilated system. This means that the intermediate space 3 between the protective lining 2 and the boiler wall, in the first exemplary embodiment the tube wall 1, is subjected to a through-flow of a protective gas - generally air - in operation. The gas (or the air) in the intermediate space is slightly pressurized relative to the fire chamber of the incinerator. Because of this it is avoided that corrosive smoke gasses can enter the intermediate space 3 from the fire chamber through leaking areas of the protective lining and attack the tube wall 1.

For feeding and discharging the protective gas in or from the intermediate space 3 of the wall inlet openings 31 and outlet openings 32 are provided in the wall, wherein the inlet openings 31 are connected with a feed channel ora plurality of feed channels 33 and are fed by said channel or channels (Figures 2 and 3). The protective gas or air feed is effected from the side of the boiler wall, wherein the inlet openings 31 penetrate the boiler wall, in this case the tube wall 1, in the region of its webs 12 (Figures 3 and 4). The outlet openings 32 (Fig. 1) penetrate the protective lining 2, as a result of which the protective gas flowing through the intermediate space 3 is discharged into the boiler.

Alternatively, the outlet openings can be arranged in the boiler wall, in particular in webs 12 of the tube wall 1, instead of the protective lining 2, and the protective gas discharged to the outside by that route (similar to Fig. 4, but instead of the inlet opening 31 shown there, a corresponding outlet opening with reversed protective gas flow direction). The protective gas discharged to the outside is preferentially sucked into a comb box 33a (Fig. 8) arranged on the outside of the boiler wall, in which for this purpose a vacuum is established. In this manner, the waste gas quantity in the boiler is not unnecessarily increased by protective gas so that the exhaust gas cleaning plant is not subjected to additional load. In addition, the protective gas discharged to the outside can be analyzed for pollutants if required.

Fig. 8 shows how the refractory wall W is inserted in an incinerating plant. The incinerating plant designated 100 as a whole comprises a material input chamber 110 and a fire chamber 120 in a manner known per se. The refractory wall W is arranged in the region of the fire chamber 100 and forms a part of its wall. The feed of protective gas or air is effected in the lower region of the wall W via the already mentioned comb box 33. In the upper wall region the further comb box or manifold 33a is arranged, via which the protective gas or air is again discharged from the refractory wall W. The discharged protective gas or the discharged air can either be fed back into the refractory wall W (arrow 113) via the lower comb box 33 or fed to the incinerating plant 100. Feeding into the incinerating plant can be effected into the input chamber 110 as primary gas or air (arrow 111) and/or as secondary gas or air (arrow 112) at the lower end of the fire chamber 120.

The outlet openings 32 are preferentially arranged in the region of the upper edge of the refractory wall, as schematically indicated in Fig. 1. The outlet openings 32 can be formed through regions of the tile joints 23 which are not sealed or alternatively, as explained above, through openings in the webs 12 of the tube wall 1. The inlet openings 31 can be arranged at the base of the wall, i.e. in the vicinity of its lower edge, as is shown in Fig. 2. The inlet openings 31 however can also be distributed over the entire wall surface or individual regions of the latter. A substantial aspect of the invention consists in that the feeding of the protective gas or the air is effected directly in the region of the continuous open grooves 21 a of the tiles 21, as is particularly evident from Figures 3 and 4. In Fig. 4 the fed-in 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 fed-in gas or the air primarily enters the open grooves 21a and in the process can spread over the entire wall without major flow resistance because of their relatively large cross section. This allows to greatly reduce the intermediate space 3 between the boiler wall or in this case the tube wall 1 and the protective lining 2 suspended in front, wherein the gap width d (Fig. 4) in practice only amounts to 1-5 mm, preferentially 1-3 mm. The tube wall 1 can also touch the tiles 21 in some areas without damage. By utilizing the grooves 21a as protective gas or air distribution channels within the wall and the reduced clear spacing d between tube wall 1 and protective lining 2 lower gas or air volumes suffice and extremely low pressure losses occur. The required pressures compared with the boiler inner pressure can be reduced to 1-10 mbar, preferentially even 1-5 mbar. This in turn produces significant energy savings in practical operation. In addition, the smaller spacing between tube wall and protective lining substantially increases the heat transfer.

Further improvement of the protective gas or air distribution within the wall according to an advantageous further development of the invention can be achieved in that some horizontal tile rows of the protective lining at certain vertical spacings, e.g. 2-4 m each, are arranged at a slightly greater spacing from the tube wall than the remaining tiles, so that horizontal transverse channels are formed via which the air can spread over the width of the wall.

In addition or alternatively, transverse channels which substantially run horizontally can also be formed in the or some tiles according to a particularly advantageous further configuration of the invention as shown in Figures 5 and 6. This is important particularly if the wall in practical operation comprises installations, for example a burner or a window, which locally interrupt the vertical grooves so that the wall parts located above or with an alternative embodiment version - with feeding of protective gas or air from the top - below the installation cannot be directly supplied with protective gas or air. Fig. 5 shows a detail of a wall with an installation 40. It is evident that the grooves 21a are interrupted in the region of the installation 40. In order to be able to supply wall parts or tiles 21 located above the installation 40 with air, the tiles 21 of the tile row located immediately above the installation are equipped with transverse channels 21b, which connect the vertically running grooves 21a of the tiles 21 of the tile row in a communicating manner. In this manner protective gas or air can flow out of the laterally neighbouring grooves 21a which are not interrupted transversely into the grooves 21a of the tiles 21 located above the installation 40 as is shown in Fig. 5 by the unmarked flow arrows.

Fig. 6 shows a tile 21 in which a transverse channel 21b is formed. As is evident, the transverse channel 21b is open on both sides of the tile 21 so that the transverse channels of neighbouring tiles form a continuous flow path.

The transverse channels 21b need not extend through the entire tile row located above the installation 40. In practice it is sufficient if the tiles located above the installation are connected at least on one side, preferentially however on both sides, with at least one neighbouring tile of the tile row located laterally outside the installation in a communicating manner. Even if the vertical protective gas or air flow is not interrupted by any installations it can be advantageous in the interest of better flow distribution to arrange tile rows with transverse channels at certain intervals or even equip all tiles with transverse channels.

According to a further important aspect of the invention the heat transfer between the tiles of the protected lining 2 and the tube wall 1 can be increased in that in the flow path of the protective gas or the air swirling elements are arranged, as is shown in Figures 9-12 in a purely exemplary manner.

In an embodiment the swirling elements can be formed by raised bent ribs 21 d in the region of the cylindrical channels 21c of the tiles 21. Alternatively or additionally, the swirling elements can also be formed through depressions 21 e in the region of the flow paths of the protective gas or the air. Finally, the swirling elements can also comprise pin-like elements 21 f which protrude into the open grooves 21a.

As already mentioned, the protective gas or air feed is effected via one feeding channel or a plurality of feeding channels 33 which are preferentially formed as a comb box. The blower required for conducting the air is for example driven by a frequency-controlled motor, wherein the overpressure in the grooves 21a measured at one or a plurality of points is utilized for controlling the blower. In this manner, the energy requirement can be optimized or minimized.

As already mentioned at the outset, the boiler wall of the refractory wall according to the invention need not be designed as tube wall, but can for example also be a normal metal wall. Fig. 7 shows schematically a second exemplary embodiment wherein the boiler wall is designed as such a flat metal wall T. With this exemplary embodiment, too, the feeding of the air into the grooves 21a of the tiles 21 and the reduction of the gap width of the intermediate space 3 achieved by this also brings about the mentioned advantages.

Claims

1. Rear-vented refractory wall, in particular for a combustion furnace, with a boiler wall (1; 1 ') and a refractory protective covering (2) disposed in front of it at a distance, of a plurality of side-by-side and above each other refractory plates (21), each of which is secured to the boiler wall (1; 1 ') by at least one plate holder (22), so that there is at least partially a gap between the boiler wall (1; 1') and the protective lining (2). 3) and with gas supply means (31) for supplying protective gas, especially air, in the space (3) between the chain wall (1; f) and the protective covering (2), characterized in that the plates (21) comprise substantially vertical extending passage grooves (21a) which are open to the boiler wall (1; 1 ') and exhibit expanded cross-section in the interior of the plates (21), and in which the plate holders (22) intervene, and that the gas supply means (31) supply the protective gas to the grooves ( 21a) and / or in the region of the grooves ( 21a) into the gap (3).

Wall according to claim 1, characterized in that the grooves (21a) align with adjacent plates (21) and are communicating.

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

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

Wall according to claim 3, characterized in that the boiler wall is a pipe wall (1) of pipes (11) connected by connections (12) and that the inlet openings (31) are arranged in the region of the connections (12).

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

Wall according to any one of the preceding claims, characterized in that it has means (32) for draining the protective gas from the gap (3) and the grooves (21a).

Wall according to claim 7, characterized in that the means for discharging the protective gas have outlet openings (32) which pass through the protective casing (2) or the boiler wall (1; 1 ') and which are preferably located in the upper region of the wall.

Wall according to any one of the preceding claims, characterized in that between the refractory plates (21) there are plate assemblies (23) which are sealed with inlaid ceramic sealing strips (23a) of refractory material and with an additional putty mass ( 23b).

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

Wall according to any one of the preceding claims, characterized in that the plates (21) of at least one horizontal plate row are arranged relative to the other plates (21) at a somewhat greater distance from the boiler wall (1; 1 '). thereby forming a transverse channel through which protective gas, especially air, can be distributed over the wall width.

Wall according to any 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) communicating connecting the vertical grooves (21a) of these plates (21) with each other.

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

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

Wall according to any one of the preceding claims, characterized in that they are provided with vortex elements (21 d; 21 e; 21 f) for the protective gas flowing in the gap (3) between the boiler wall (1; 1 '). and the protective clothing (2).