WO2015070953A1

WO2015070953A1 - Furnace wall arrangement

Info

Publication number: WO2015070953A1
Application number: PCT/EP2014/002930
Authority: WO
Inventors: Rainer Weiss; Jürgen Schlax
Original assignee: Saint Gobain Industriekeramik Rödental Gmbh
Priority date: 2013-11-12
Filing date: 2014-10-31
Publication date: 2015-05-21
Also published as: DE202014009337U1; EP3069079A1; PL3069079T3; EP3069079B1; DE102013018936B4; DE102013018936A1

Abstract

The invention relates to a furnace wall arrangement of an industrial furnace having a furnace wall and having at least one protective element which is composed of fire-resistant material and which is fastened at one end to an inner face of the furnace wall. The object of the present invention is to propose a tank wall arrangement which is distinguished by good heat transfer between the protective element and the furnace wall. The object is achieved by a furnace wall arrangement which has cooling ribs which are arranged between the inner face of the furnace wall and an outer face of the protective element, wherein the cooling ribs have a specific thermal conductivity which is greater than a specific thermal conductivity of a cleaving medium between the furnace wall and the protective element.

Description

Furnace wall arrangement

The present invention relates to a furnace wall assembly of an industrial furnace with a furnace wall and with at least one on one side attached to an inner side of the furnace wall protective element made of refractory material.

In such a furnace wall arrangement, the furnace walls are protected by the protective elements from heat and flue gas, which arise in the inside of the furnace or boiler combustion chamber. The furnace wall is formed, for example, as a closed boiler tube wall and optionally on the ground as a broken through Lüftungssch strand rust. The boiler tube wall is formed, for example, from parallel pipes connected to one another via pipe fins or to individual, partially back-fixed pipes. The tubes are usually flowed through by a cooling fluid. The cooling fluid used is preferably water whose boiling point can be adjusted to over 250 ° C. by a correspondingly high pressure.

The existing of a refractory material protective elements, for example, by mechanical holding devices, such. Hook, and / or connected by mortar with the furnace wall assembly.

A falling under the above-mentioned species furnace wall arrangement is known from DE 102 04 240 AI. In the solution presented there, the boiler tube wall has holding elements and the protective elements have recesses in which the holding elements are provided. Through holes in the protective elements anchoring elements through

Holes of the holding elements are pushed to anchor the protective elements to the holding elements.

The gap between the furnace wall and protective element is in the prior art in the operation of the furnace partially by a purge gas or a slit medium, as a so-called ventilated system, such as air, flows through to separate corrosive gases that arise in the combustion chamber as well as possible from the furnace wall , In this solution, a poor heat transfer between the protective element and the furnace wall is disadvantageous because heat is transported almost only by heat radiation and hardly by heat conduction. As a result, the protective elements on the combustion chamber side have a high surface temperature, which leads to premature wear of the protective elements and low heat extraction from the respective zone of the boiler.

A better heat transfer between the protective element and the furnace wall is achieved by filling the gap with mortar or by pouring the gap with cement. In DE 20 2004 020 448 U l, the intermediate space is filled with an adhesive, which at the same time serves to secure the protective elements to the furnace walls. A disadvantage of this solution is a relatively high installation and disassembly effort during repair work.

In the prior art, in general, only a few furnace walls namely the side walls and ceilings are covered with protective elements.

It is therefore the object of the present invention to propose a boiler wall arrangement, which is characterized by a good heat transfer between the protective element and the furnace wall.

The object is achieved by a furnace wall arrangement of the type defined above, which has arranged between the inside of the furnace wall and an outer side of the protective element cooling fins, wherein the cooling fins have a specific thermal conductivity, in particular greater than specific Wärmeleitfähigkeiten one between the furnace wall (2) and the protective element (3) located gap medium, a between two protective elements arranged mortar or cement and the protective element (3). The cooling fins ensure good heat dissipation from the protective elements into the furnace wall. As a result, the protective elements are cooled from their backs, which has an advantageous effect on the life of the protective elements.

In an advantageous embodiment of the furnace wall arrangement according to the invention, the cooling ribs are elongate profile rods which are partially partially and / or non-positively arranged in matching with the cooling fins grooves which are formed in the protective element.

The profile bars are in a useful embodiment long rectangular solid profiles, in particular in the form of strips. In other embodiments, the profile bars have no filled cross section, but their cross section occupies only parts of a surface, for example, occupies a U-shaped profile three edges of a surface. In a further embodiment, the cooling fin is constructed in layers of a graphite foil to the desired thickness. In this case, strips of graphite foil having a thickness, in particular in the range from 0.4 to 1 mm, are stacked on top of one another and if necessary glued together. The rod-shaped configuration of the cooling fins is particularly advantageous if the furnace wall also has linearly extending structures, for example tubes. The cooling fins are in this case preferably arranged parallel to the linear structures of the furnace wall, so that large contact surfaces between the furnace wall and the cooling fins result, which in turn cause good heat conduction from the cooling fins in the furnace wall. The grooves in the protective elements ensure large contact surfaces between the protective elements and the cooling ribs and thus good heat conduction from the protective elements into the cooling ribs. In addition, the cooling fins can advantageously be mechanically fastened or glued in the grooves. A purge gas can be passed between adjacent linearly extending cooling fins, the cooling fins serving as the channel walls of a purge gas channel. At Spülgaszuführungen and purge gas discharges of the furnace are usually no adjustments required. In some embodiments, for example, in sheet-like furnace walls, the cooling fins have other than elongated shapes, such as circular.

According to preferred embodiments of the furnace wall arrangement according to the invention, the profile bars have an I-shaped cross-section or a cross-section in the form of a trapezoidal tapered "I" s, the wider side of the trapezoid engaging in the Oven wall and the narrower side of the trapezoid is provided in the groove of the protective element. In these embodiments, the cooling fins have particularly simple geometric shapes, which allow a particularly simple manufacture and processing of the cooling fins. The cooling ribs with the cross section in the form of a trapezoidally tapered "F", so slightly pointed cooling fins, partially facilitate a full iges insertion of the cooling fins in the grooves. Alternatively, other profile bars are used, for example, those whose cross section is composed of a circular arc and radially extending from the circular arc straight ribs or layered graphite foil.

In some advantageous variants of furnace wall arrangements according to the invention, the cooling ribs are glued into the protective element. The adhesive ensures a good thermal contact, for a gas-tight connection and also for a mechanical pre-assembly, which ultimately contributes to ease of assembly and disassembly of the furnace wall assembly. In alternative embodiments of the invention, cooling fins are attached to the furnace wall, for example glued, screwed, clamped or soldered.

In further furnace wall arrangements according to the invention, the cooling fins are made of a heat-resistant elastic material. As a result of the elasticity which is also present under thermal cycling, such cooling fins, when clamped in the installed state between the furnace wall and the protective elements, remain permanently in a mechanical contact with the furnace wall and on the protective element. The cooling fin material is soft and only exerts small forces on the clamping components during elastic deformation. Of the pressed on the furnace wall cooling fins only permissible small pressure forces are exerted on the protective elements, so that the protective elements are not damaged.

In a preferred embodiment of the furnace wall assembly according to the invention, the heat-resistant elastic sealing material is expanded graphite. This material is characterized by a good thermal conductivity, elasticity and a good chemical resistance to corrosion by flue gas. The specific thermal conductivity of the material used is preferably 100 W m ^"1 K ^" 'large or larger. Consequently, this material is particularly well suited to the formation of cooling fins. In alternative embodiments, other materials, such as metal bellows or metal foams are used. In another advantageous variant of the furnace wall arrangement according to the invention, the cooling fins are constructed in layers of a Graphitfol ie. Graphite foil is flexible because of its small thickness. Multilayer arrangements of the graphite foil are processed in embodiments of the invention, for example as a lamellar stack or as a curl, in particular to a flexible seal.

Preferably, the furnace wall assembly according to the invention is dimensioned such that the occurring temperatures of the cooling fins always remain below 600 ° C. The insides of the protective elements are facing the combustion chamber in the high temperatures of, for example, 1 1 50 ° C prevail. This heats the inner surface of the protective elements. In prior art furnace wall assemblies, temperatures up to greater than 1000 ° C. were measured on the surfaces of the inside of the protective elements. The outer sides of the protective elements are cooled, so that they have a lower surface temperature. Accordingly, the protective element in the furnace wall assembly according to the invention are generally well cooled, so that temperatures occurring low and the durability of the protective elements is high. The cooling fins are thermally conductively connected to the outer sides of the protective elements, so that they assume almost the same temperatures, at least in the vicinity of the boundary surfaces with the protective elements. Excessive temperatures can damage the cooling fins, for example, oxygen can oxidize graphite at temperatures above 600 ° C. Accordingly, material thicknesses and other parameters that affect the temperatures occurring are set so that predetermined temperature limits are not exceeded.

According to an advantageous development of the furnace wall arrangement according to the invention at least one graphite foil is arranged on the furnace wall, wherein the graphite foil is clamped between adjacent cooling ribs. In this development, the good chemical resistance of graphite is exploited in order to cover areas of the furnace wall which are at risk of corrosion and to protect against chemical stress by flue gas.

In two variants of the furnace wall arrangement according to the invention, the furnace wall is designed as a boiler tube wall, in which parallel tubes are connected to one another via pipe fins, or as a grate. Side walls and ceilings of industrial furnaces are often designed as boiler tube walls. The boiler tube walls are protected by plate-shaped protective elements. clothes, the sides of which are partially profiled inversely to the boiler tube walls to ensure constant distances between the furnace wall and the protective element.

Surprisingly, it was found that only small forces are transmitted to the protective elements in the furnace wall arrangements according to the invention by the cooling fins, so that the grate of the boiler can be clad with suitable protective elements. In such an arrangement, therefore, the rust is to be understood as a furnace wall, which is part of a furnace wall arrangement according to the invention as well as the protective element as such.

In individual standing pipes of a furnace wall arrangement, the protective elements are preferably formed as waisted plates, that is as plates, which are formed at two opposite ends with recesses, in particular those with tei lkreisförmigem cross-section, wherein the recesses surround the tubes of the furnace wall with distance. The cooling fins are preferably received in the region of these recesses and pass through the gap-shaped annular space between the recess and the tube. The plates are arranged above and next to each other to form the furnace wall assembly and are guided loose, so that a fixing to the furnace wall can be omitted.

Preferably, these plates pass through the space between adjacent tubes and project on both sides of the tube plane. Incidentally, the plates are constructed of the same material as described above, which also applies to the cooling fins.

Finally, it should be noted that the material of the cooling fins can be suitably selected, but graphite is preferably used.

The advantage of the described embodiment is a very good protective function. Furthermore, the tubes are more or less completely surrounded by the cooling fins. The assembly is very simple and separate fasteners against the furnace wall are unnecessary.

The present invention will be explained in more detail below with reference to figures purely schematically, wherein 1 shows a cross section through a first embodiment of the wall assembly according to the invention,

Fig. 2 shows a protective element of the arrangement of Figure 1 in a perspective view on its back, as well as

Fig. 3 shows a further embodiment of a furnace arrangement in perspective.

Fig. 1 shows schematically a preferred Ausführungsbeispiei a furnace wall assembly 1 according to the invention in cross section. Illustrated components of the furnace wall assembly 1 are a furnace wall 2, protective elements 3 and between an inside 4 of the furnace wall 2 and outer sides 5 of the protective elements 3 clamped cooling fins. 6

The furnace wall 2 is in the illustrated variant a boiler tube wall, which tubes 12 and pipe fins 13 has. Through the tubes 12 water is passed during operation of the furnace, through which heat is removed from the furnace wall 2.

In the protective elements 3 Aufhängausnehmungen 1 1 are formed, with which the protective elements 3 are suspended from holding elements 10, wherein the holding elements 10 are arranged on the furnace wall 3, in particular fixed. In the illustrated embodiment, the protective elements 3 are made of silicon carbide plates. In other embodiments, the protective elements 3 are formed of other refractory materials. Between adjacent protective elements 3 there are joints 8, which are grouted with suitable mortar 9, for example a SiC mortar or cement.

Between the furnace wall 2 and the protective elements 3 cooling fins 6 are clamped, which in the illustrated embodiment, preferably elastic and in particular made of expanded graphite rods or strips, here for example, and preferably cuboid bars with an I-shaped cross-section. In the spatial dimension perpendicular to the plane shown, the cooling fins 6 and the grooves 7 clearly have larger linear expansions than the illustrated cross-sectional edges. The cooling fins 6 are suitably against the furnace wall 2 and to the wall elements, so that a good heat conduction from the wall elements 3 is ensured via the cooling fins 6 in the furnace wall 2. 2 shows schematically a perspective view on the outside 5 of a wall element 3. The edge of the wall element 3 shown in front is a cutting edge, on which the structure of the grooves 7 and the suspension recess 11 can be seen well.

In the grooves or joints 7 strips are used with a trapezoidal cross section in a preferred embodiment, not shown, with a measured between the parallel sides of the trapezoid width 10 mm, a measured at the wide side of the trapezoidal length 8 mm and an the narrow side of the trapezium measured length is 7 mm, which is preferred, but only by way of example. The cooling fins are in embodiments preferably made of the expanded graphite material "Ecophit L".

FIG. 3 again shows, purely schematically and in perspective, a part of a further embodiment of a furnace wall arrangement according to the invention. Here, the same components with the same reference numerals as in Figures 1 and 2 are designated. The furnace wall is gebi Ldet by spaced tubes 12, which span, so to speak, a boiler tube wall, wherein during operation of the furnace through the tubes cooling water is passed to dissipate heat. Instead of the protective elements 3 according to the embodiment in Figures 1 and 2 now protective elements in the form of waist stones 20 are used, which are no longer attached directly to the furnace wall, as in the previous embodiment, but compared to or on the tubes 12 loosely , These waist blocks 20 are arranged above and next to one another to form the furnace wall arrangement, ie in the manner of a brick wall.

As FIG. 3 shows, the protective elements 3 designed as waiststones are provided, on two opposite sides facing the tubes 12, with recesses 22, similar to the first exemplary embodiment, which here preferably have a semicircular cross section. In these recesses 22 analogous to the first embodiment, the corresponding cooling fins 6 are added. These cooling fins are in turn in contact with the tube 12 and the Tai llenstein and are also ausgebi end, especially material designed according to the first embodiment, that is preferably formed of heat-resistant material, in particular expanded graphite with particular elastic material properties. The waist stones are plate-shaped and - as has already been stated above, according to the height of the furnace wall order according to many stacks stacked and arranged side by side, so that compared to the formation of the protective elements in Figures 1 and 2, the protective elements and the free space between the Pass through tubes 12 and beyond ebenfal ls projecting on both sides and also in combination with the juxtaposed waist stones 20, the tube 12 substantially fully enclose, so that the cooling fins 6 are distributed so to speak over the entire circumference of the tubes 12. This increases the efficiency in this embodiment. The waist blocks 20 are materially designed according to the support elements 3 explained in connection with the first embodiment. Advantage of this embodiment is that the plates no longer need to be attached to one side of the furnace wall, but loosely guided along the tubes 12 and arranged.

In a preferred, non-mandatory embodiment, the waist panels have dimensions of 147 x 1 76 mm in length and width and a thickness of 1 00 mn. The pipe spacing can be 150 mm with a pipe diameter of 57 mm. With a pipe spacing of 225 mm and pipe diameters of 57 mm, the waist stones are preferably 223 x 1 87 x 64 mm.

Advantageous properties of graphite are high thermal conductivity and high chemical resistance to aggressive gases released in the furnace. The heat resistance of graphite in air is sufficiently high for the application described because the graphite is cooled by the pipe wall. The orientation of the cooling fins, which are in particular graphite strips along the tubes of the tube wall and along the protective elements extending along the tubes, ensures a high heat transfer from the protective element into the furnace wall. This contributes to a considerably higher efficiency of the furnaces compared to furnaces with ventilated protective elements. In addition, the surface temperature at the hot side of the protection element is smaller than in the prior art. As a result, the protective elements have an increased life. In addition, the adhesion of fly ash and slag is less pronounced than in the prior art.

Claims

claims

A furnace wall arrangement (1) of an industrial furnace with a furnace wall (2) and with at least one protective element (3) of refractory material fixed on one side to an inner side (4) of the furnace wall, characterized in that the furnace wall arrangement between the inside (4) of the furnace wall Oven wall and an outer side (5) of the protective element (3) arranged cooling ribs (6), wherein the cooling ribs (6) have a specific thermal conductivity greater than specific Wärmeleitbigkeiten a gap between the furnace wall (2) and the protective element (3) and / or a mortar arranged between two protective elements and of the protective element (3).

2. furnace wall arrangement (1) according to claim 1, characterized in that the cooling ribs (6) are elongated profile bars which at least partially positive and / or non-positively in the cooling fins (6) matching grooves (7) in the protective element ( 3) are formed, are arranged.

3. furnace wall assembly (1) according to claim 2, characterized in that the profile bars have an I-shaped cross section or a cross-section in the shape of trapezoidal tapered "I" s, wherein the wider side of the trapezium in abutment against the furnace wall (2) and the narrower side of the trapezoid in the groove of the protective element (3) is provided.

4. furnace wall arrangement according to claim 1, characterized in that the cooling ribs (6) in the protective element (3) are glued.

5. furnace wall assembly (1) according to claim 1, characterized in that the cooling ribs (6) consist of a heat-resistant elastic material.

6. furnace wall assembly (1) according to claim 5, characterized in that the heat-resistant, elastic material is expanded graphite.

7. furnace wall assembly (1) according to claim 1, characterized in that the cooling fins are constructed in layers of graphite foils.

8. furnace wall assembly (1) according to claim 6 or 7, characterized in that the furnace wall assembly (1) is dimensioned such that the occurring temperatures of the cooling fins (6) always remain below 600 ° C.

9. furnace wall arrangement (1) according to claim 1, characterized in that on the furnace wall (2) at least one graphite foil is arranged, wherein the graphite foil between adjacent cooling fins (6) is clamped.

10. furnace wall assembly (1) according to claim 1, characterized in that the furnace wall (2) as a boiler tube wall, in the parallel tubes (12) via pipe fins (13) are interconnected, or formed as a grate.

1 1. Oven wall assembly according to one of the preceding claims, characterized in that the protective elements (3) by plates (20) are formed, which are guided loosely within the furnace wall assembly, each plate on two opposite sides recesses (22), preferably in a circular shape , and in the recesses (22) the cooling ribs (6) are arranged.

12. furnace wall arrangement with a furnace wall formed by spaced coolant tubes (12), characterized in that the plates (20) pass through the space between two tubes (12) projecting on both sides of the plane defined by the tubes plane, wherein preferably the recesses (22) adjacent plates (20) engage around the tubes (12).

13. Oven wall arrangement according to one of claims 1 1 or 12, characterized in that the plates (20) for forming the furnace wall arrangement are arranged above and next to each other.

14. Furnace wall arrangement according to one of the preceding claims, characterized in that the specific thermal conductivity of the cooling ribs (6) is greater than a specific thermal conductivity of the furnace wall (2).

15. Oven wall protection element characterized by features of at least one of the preceding claims.