US 2654219 A
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Oct. 6, 1953 T. ZABA METAL COMBUSTION CHAMBER Filed Aug. 28, 1951 7 v 2 a 0 0 I o 0 Q o c m Q Q 0 0 0 0 0 0 0 2v e o o o o 0 0 0 O 0 0 s o o 0 0 v o, Ma omomomo omol w e o 0 0 0 0 0 0 0 o o 0 o o o o o 4 090 0 0 0 0 0 0 0 0 0 0 0 0 UT] M m 4 6 7 3 b J ATTORNEYS.
Patented Oct. 6, 1953 METAL COMBUSTION CHAMBER Tadeusz Zaba, Wettingen, Switzerland, assignor to Aktiengesellschaft Brown, Boveri & Cie., Baden, Switzerland, a joint-stock company Application August 28, 1951, Serial No. 244,047 In Switzerland September 4, 1950 6 Claims.
This invention relates to metal combustion chambers for the generation of hot pressure gases for various industrial purposes, and more particularly to combustion chambers for producing fuel gases for gas turbine plants,
It is known to produce hot combustion gases, and particularly hot pressure gases for gas turbine plants, in metal combustion chambers of generally cylindrical form having an outer wall or shell into which air introduced under pressure and an inner wall or shell within which the combustion takes place. The inner wall which delined the combustion space was cooled by the annular stream of air flowing through the interspace between the walls and alsoby air flowing radially into the combustion space through openings in the inner wall to form a boundary layer of cooling air flowing along the inner surface of the inner wall. The air for combustion and cooling was of course introduced under a igher pressure than that developed in the combustion space and, in the prior combustion chamhers, the inner wall where directly heated by the flame was strongly stressed by the full pressure drop between the outer air space and the combustion space. Furthermore, with some of the prior constructions, the cooling air was introduced into the combustion space at such high speed and volume as to effect a too vigorous cooling of the flame.
Objects of the present invention are to provide metal combustion chambers which eliminate such defects or disadvantages of the prior equipment and which substantially reduce the mechanical stresses imposed upon the metal wall which is directly exposed to the combustion flame. Objects are to provide metal combustion chambers of the double-walled type in which the inner wall is formed by a plurality of concentric perforated shells connected at their opposite ends only a fraction of the pressure drop between the outer shell and the combustion space. More specifically, objects of the invention are to pro vide metal combustion chambers of the character above-stated in which the total area of the perforations of the innermost shell of the inner wall is at least equal to the total area of the perforations of the outer shell or shells.
These and other objects and the advantages of the invention will be apparent from the following specification when taken. with the accompanying drawing in which:
Fig. 1 is a central vertical section through a metal combustion chamber embodying the invention; and
Fig. 2 is a fragmentary vertical section through another inner wall construction embodying the invention.
In Fig. 1, the reference numeral l identifies the conduit through which pressure air is introduced into the outer cylindrical pressure-resistant casing or shell 2 of the combustion chamber. The combustion space extends axially of and is radially spaced from the casing 2 by an inner wall 3 comprising concentric perforated shells 3a, 3b which surround the flame zone, and a cylindrical sleeve 4 which is telescoped over and radially spaced from the multiple shell wall 3. The annular space between the shells 3a, 3b is closed at its lower end by an imperforate anulus 3c, and is closed at its upper end by the conical wall 5 forming the outer boundary of the primary air inlet to the combustion zone. The fuel nozzle 8 extends axially through the hollowv conical chamber 1 which forms the inner boundary of the annular inlet for the primary combustion air and whose end walls are perforated for the flow of cooling air around the tip of the fuel nozzle. Inclined or curved vanes 8 of known type extend across the air inlet opening to impart a tangential component or swirl to the annular air stream which is introduced around the fuel stream projected from the nozzle 6.
The shells 3a and 3b of the inner wall portion are perforated for the radial flow of air for combustion and cooling, and preferably are provided with a multiplicity of relatively small perforations 9 and i0 respectively. The perforations are distributed over the entire extent of each shell, and preferably are uniformly distibuted and so dimensioned and closely arranged that a circumferentially complete layer of cooling and secondary combustion air is formed at and flows along the inner surface of the innermost shell 3b. The total area of the perforations I ll of the inner shell 3b is preferably equal to or greater than the total area of the perforations 9 of the outer shell 3a, whereby the inner shell-is stressed by about one-half or less of the total pressure drop of the combustion and cooling air flowing through the inner wall.
Additional cooling air may be introduced around or combined with the combustion gases through the annular interspaces H and I2 between the sleeve 4 and, respectively, the wall portion 3 and the casing 2, and through radial openings l3 through the sleeve 6.
The inner wall membersmay be supported on and axially of the outer casing 2 in any desired manner. When, as illustrated, the combustion chamber is vertically arranged, the wall 3 and sleeve 4 may be provided with radially spaced lugs M and 15, respectively, for supporting the same upon lugs 16 and all respectively welded or otherwise secured to the inner surface of the casing 2.
As shown somewhat schematically in Fig. 2, the inner wall 30 of the combustion'chamber may include more than two perforated sleeves, and specifically three sleeves 3114 9100 with perforations 3la-3lc respectively. The'total area of the perforations 31b of the sleeve 3% surrounding the innermost sleeve 300 is preferablyless than the total area of the perforations .of the. nther sleeves of the inner wall 30.
The advantages of the invention are that the inner shell which is most endangered by the high combustion temperatures isrelievedfrom azheavy mechanical stress and-may therefore :be .of lighter weight than in prior constructions. The .azlr enters the --combustion--zone:at-relatively low speed through the multiplicity of perforations and thereby avoids an intensive cooling of the flame, and the multiplicityof :small air jets which impinge upon the outer surface of the innermost jacket afiord a very efficient cooling .of that jacket.
It is to be understood that the invention 'is not limited to the particular constructions herein illustrated and described as 'variousmodifications which may occur .to "those familiar with the art fall within the spirit and scope of the invention as set forth in the following claims.
1. A .metallcombustionchamher for the production of hot gases; said lchamher comprising :an outer wall providing .a pressure-resistant tea-sing having an inlet for air :under pressure, an inner 'wall within and spaced from said casing wall by an interspace through which the pressure air may flow, said inner wall comprising a plu alit .of concentrically arranged perforated shells and imperforate annular walls connecting the adjashells of .said inner wall are distributed substantially 'nrfiform'ly over the entire extent thereof.
3. A metal combustion chamber as recited in claim :1, wherein the perforations of the innermostshellof :said inner wall are closely arranged to constitute means forming a layer of cooling and combustion air flowing along the inner surface of said innermost .wall and surrounding the combustion gases.
4. Azmetal .com'bustion chamber as recited claim 1, wherein'thetotal area of the perforations of the innermost shell of said .inner wall is not less than the total area of the perforations of an outwardly arranged shell of said inner wall.
5. A :metal combustion chamber as recited in claim '1, wherein the total area of the perforations of said innermost shell is greater than that of an outer shell.
6. A metal combustion chamber as recited in claim 1, wherein saidinner wall comprises three other shells.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 812,513 Moreno et a1. Feb. 13, 1906 2464;954 Stephens July 4, 1-939 2398528 :Way 'Feb. 28, 1950