Combustion chamber construction

The inner wall of a combustion chamber is composed of a plurality of ceramic plates which are suspended from the outer wall of the chamber by being hooked over mounting portions of the outer wall; this eliminates the need for screws, bolts, welds or the like and facilitates mounting and dismounting of the plates. The plates define with the outer wall a clearance into which cold air is admitted; the upper and lower edges of adjacent plates define with one another respective air gaps communicating with this clearance so that air streams enter the combustion space through these gaps. These air streams prevent the deposition of ash and other contaminants on the inner surfaces of the plates.

BACKGROUND OF THE INVENTION 
The present invention relates to a combustion chamber. 
More especially, the invention relates to a combustion chamber which is 
particularly well suited for--although not restricted to--use in refuse 
incinerators. 
Special problems exist in the operation of refuse incinerators, because the 
refuse mix tends to produce combustion products which form slag deposits 
on the inner wall of the combustion chamber. When this occurs, quite 
substantial difficulties result in terms of further operation of the 
incinerator. To overcome this problem it is known to make the inner wall 
of the combustion chamber--which is spaced with clearance from the 
gas-tight outer wall--of plates having or defining openings through which 
air can be passed from the clearance into the combustion chamber. This air 
prevents the settling of deposition-forming matter on the plates and the 
problem is thus overcome. However, the prior art is still possessed of 
difficulties which have heretofore not been solved. 
An incinerator is known from German Allowed Application DE-AS No. 2,317,064 
in which the plates are of metal and define air-outlet gaps with one 
another. A problem with this construction is the danger that--should the 
air supply to the outlet gaps suddenly fail--the metallic plates will 
corrode under the influence of the temperature prevailing in the 
combustion chamber, unless specially heat-resistant metal is used which, 
however, is then again very expensive. Also, metallic plates are 
relatively heavy and require a correspondingly massive supporting 
structure to sustain that weight. 
Another proposal, made in VGB Kraftwerkstechnik 57 (1977), pp. 341-344, 
suggests the use of ceramic plates provided with air-outlet holes arranged 
in form of a grid or raster. These plates are then screwed or bolted to 
the outer combustion-chamber wall. They are, however, also relatively 
heavy and quite expensive in terms of manufacture and installation. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to overcome the 
problems of the prior art. 
A more particular object of the invention is to provide an improved 
combustion chamber which avoids the prior-art drawbacks. 
A still more particular object is to provide such a combustion chamber in 
which the inner wall is composed of plates having a relatively low weight. 
Another object is to provide a combustion chamber of the type in question, 
i.e. one which is well suited for use with incinerators but is not limited 
to such use, in which the aforementioned plates are highly heat-resistant 
even in the event of an interruption in the flow of incoming air. 
A concomitant object is to provide such a combustion chamber wherein the 
plates can be installed, removed and replaced in a simple, time- and 
cost-saving manner. 
In keeping with these objects, and still others which will become apparent 
hereafter, one aspect of the invention resides in a combustion chamber, 
particularly for refuse incinerators. Briefly stated, such a combustion 
chamber may comprise first means forming an outer wall bounding a 
combustion space, and second means forming an inner wall also bounding 
this space and comprising a plurality of plates each having an upper and a 
lower edge region. There are further provided cooperating mounting 
portions on the first means and on the upper edge regions of the plates, 
so that the plates can be suspended vertically--or at least substantially 
vertically--on the first means in order to define with the same a 
clearance through which the deposition-preventing air is blown. 
The plates may be of any suitably heat-resistant ceramic material known 
from the prior art; silicone carbide has been found to be especially 
advantageous. Due to the material used, the plates are relatively light in 
weight and, of course, their material is not subject to the kind of heat 
damage experienced by metal plates in the event the supply of air is 
interrupted. 
The cooperating mounting portions include parts or elements on the outer 
wall which are vertically spaced from one another by a distance smaller 
than the distance between the upper and lower edges of the respective 
plates, and parts or elements on the upper plate edge regions which are 
shaped so that they can be hooked or hung over the parts on the outer 
wall. Thus, the plates are suspended on the outer wall merely by hooking 
their mounting portions over those on the outer wall; no installation work 
such as screwing, bolting or other securing is required. Such hooking (and 
unhooking if the plates are to be detached for inspection and/or 
replacement) is extremely quick and can be carried out for any individual 
plate without in any way affecting adjacent plates which remain untouched 
by such an operation. 
Moreover, the plates are relatively inexpensive to produce, since the 
air-outlet gaps are formed between their edge portions; which is to say, 
the plates are slid and need not be formed with air holes as in some of 
the prior art, a manufacturing sequence which adds considerably to the 
cost of the prior-art plates. 
The plates according to the present invention have good thermal 
conductivity so that the inner wall formed by them remains relatively cool 
at all times. This means that it is difficult or even impossible for hot, 
more or less viscous ash particles to adhere to this inner wall. 
Finally, the inflowing air coming through the air inlet gaps between the 
suspended plates--and whose speed and quantity per unit/time are variable 
and can be accommodated to the momentary operating conditions, as is known 
per se--prevents the build-up of heat at and adjacent the 
combustion-chamber walls, and this heat is instead restored to the 
combustion process. 
The invention will hereafter be described with reference to an exemplary 
embodiment, as illustrated in the appended drawing. However, it is to be 
understood that this is for purposes of explanation only and that the 
protection sought for the invention is defined exclusively in the claims.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The combustion chamber shown in FIG. 1 will be assumed to be that of a 
refuse incinerator; however, as already mentioned before, this is for 
purposes of explanation only and the invention is in no way limited to 
refuse incinerators. 
The combustion chamber will be seen to have a combustion grate 1 which is 
here constructed of a series of cylindrical rollers, air-cooled side walls 
2 and a ceiling 3. The other components of the system, e.g. the 
heat-recovery boiler connected with the chamber, are not illustrated since 
they are known per se. 
The side walls 2 of the chamber are composed of an outer wall and an inner 
wall. The outer wall, in turn, is composed of a support or frame structure 
constituted by vertical beams 4 which are connected by horizontal beams 5, 
and by a gas-tight sheet-metal enclosure 6 (shown only in part in FIG. 2) 
which is screwed, welded, bolted or otherwise secured to the frame 
structure (here to that side thereof which faces inwardly towards the 
combustion space). The inner wall is inwardly spaced from the outer wall 
and is constituted of a plurality of the aformentioned plates (here 
designated with reference numeral 7) of ceramic material. These define 
with the outer wall a clearance 8 with which air supply pipes 9 
communicate, via which the clearance 8 receives cold air from outside. 
Adjacent plates 7 in turn define between their adjacent edges respective 
air inlet gaps 10 through which the air admitted into the clearance 8 
escapes and is allowed to enter into the combustion chamber. 
In accordance with the invention, mounting or suspending portions are 
provided on the outer and inner walls and cooperate with one another for 
suspending the plates 7 parallel or substantially parallel to the 
sheet-metal enclosure 6. The portions 11 are provided on the horizontal 
beams 5 to which they may be screwed, bolted, welded or otherwise secured; 
they are composed of a highly heat-resistant alloyed castable material, 
for example. 
The vertical spacing between these portions 11 is so chosen that it is 
smaller than the height (i.e. vertical dimension) of the plates 7, in 
order to assure the existence of the gaps 10. Thus, decreasing the 
vertical distance between portions 11 assures the existence of gaps 10. 
Each of the portions 11 has two functions: it suspends one of the plates 7 
at the upper edge region thereof and it engages and supports (from behind) 
the lower edge region of the respectively superjacent plate 7 (see FIG. 
3). For this purpose it has been found to be especially advantageous to 
make the portions 11 in form of U-shaped profiles (they may be cut-offs 
from a U-shaped profile beam) and to so mount them on the beams 5 that the 
two arms of their U-shaped configuration are located in vertically spaced 
planes. 
As already mentioned, the plates 7 are of ceramic material which may, but 
need not be, silicone carbide. The mounting portions on the upper edge 
regions of these plates 7 are designated with reference numeral 12; they 
are seen (FIG. 3) to be generally hook-shaped and may be separate elements 
secured to the plates 7. However, it is currently preferred--and maximum 
manufacturing economy is obtained--for them to be formed of one piece with 
the respective plate during manufacture of the same. The lower arm 13 of 
each of the portions 11 is provided with a bead 14 which is so shaped that 
the portion 12 of a respective plate 7 can be hooked over it, thus 
suspending the plate from the lower arm 13. In turn, the lower edge region 
of the thus suspended plate 7 rests against the upper arm 15 of the next 
lower (subjacent) portion 11, so that--although the plates 7 are freely 
suspended without any screws or the like--they cannot swing outwardly 
against the enclosure 6. 
FIGS. 2 and 3 shows that a hook 16 extends from any two of the plates 7 and 
has a head 17 which overlaps two adjacent plates 7. The plates 7 have 
lateral recesses 18 which receive the head 17. Hook 16 has a downwardly 
angled part 19 (FIGS. 2 and 3) which engages in a slot or opening 20 in 
the upper arm 15 of the respective portion 11. The cooperation of the 
portions 11 and 12 allows the plates 7 to be individually mounted and 
dismounted without requiring any changes whatsoever in the mounting, 
positioning or presence of laterally or vertically adjacent plates 7. 
As FIG. 3 shows, the upper end and lower edges 7a, 7b of the plates 7 are 
bevelled at identical angles, so that the edge 7a of each subjacent plate 
defines with the edge 7b of the respective superjacent plane one of the 
air gaps 10. The cold air admitted into clearance 8 via the pipes 9 enters 
the combustion chamber through these gaps 10. It will be noted that the 
bevels on the edge portions 7a, 7b are such that the air streams passing 
through the gaps 10 flow into the combustion chamber in downward 
direction. These air streams have the dual purpose of preventing the 
deposition of ash and similar matter on the plates 7 (i.e. on the sides 
thereof which face towards the combustion space) and of preventing the 
entry of such matter through the gaps 10 into the clearance 8 (due to the 
downward component of movement of the air streams). 
The clearance 8 is subdivided into horizontal sections by sheet-metal 
separators 21 which rest on (and may be additionally secured to) the 
portions 11. Each of these sections communicates with one of the air 
supply pipes 9 (see FIG. 3). However, it is clear that the clearance 8 
could, instead, be divided into vertical sections by the use of vertically 
oriented separators; in fact, both horizontal and vertical separators may 
be used in conjunction with one another, if desired. 
The invention has hereinbefore been described with reference to its 
application in the combustion chamber of a refuse incinerator. However, as 
mentioned earlier, the invention can be used in combustion chambers of 
other types of installations and is in no way limited to refuse 
incinerators. Furthermore, the invention is not limited to the specific 
details shown, since various changes and modifications may be made in and 
with respect to the illustrated exemplary embodiment without departing 
from the gist of the invention. Accordingly, it is to be understood that 
the protection sought for the invention is defined solely by the appended 
claims.