US3398528A - Evaporation type burner - Google Patents

Description

HARUMITSU NAKAMURA ETAL Aug. 27, 1968 EVAPORATION TYPE BURNER 2 Sheets-Sheet 1 Filed Oct.

INVENTOR, HARUMITSU NAKAMURA ET AL ATTORNEYS Aug. 27,1968 HARumrsu NAK-AMURA ETAL 9 EVAPORATION TYPE BURNER 2 Sheets-Sheet 2 Filed Oct.

INVENTOR. HARUMITSU NAKAMURA ATTORNEYS United States Patent 3,398,528 EVAPORATION TYPE BURNER Harumitsu Nakamura and Shoichi Tsuji, Tokyo-t0, Japan, assignors to Ishikawajima-Harima Jukogyo Kabushiki Kaisha, Tokyo-to, Japan, a Japanese company Filed Oct. 3, 1966, Ser. No. 583,574 Claims priority, application Japan, Oct. 5, 1965, 40/ 60,868 Claims. (Cl. 6039.71)

ABSTRACT OF THE DISCLOSURE An evaporation type burner for jet engines or gas tur bines. The burner has a pair of combustion chamber walls and a pair of evaporation walls are situated between the pair of combustion chamber walls at the upstream regions of the latter. The upstream ends of the combustion chamber walls are respectively connected with the upstream ends of the evaporation walls to define therewith a pair of combustion spaces which are closed in the upstream direction and communicate only with the space between the combustion chamber walls downstream of the evaportion walls. A separation wall means is situated between the pair of evaporation walls and a pair of fuelsupply means direct fuel between the pair of evaporation walls on opposed sides of the separation wall means, the upstream end of the space between the evaporation walls communicating with an air inlet so that a mixture of fuel and air will form at opposed sides of the separation wall means along the inner surfaces of the evaporation walls. The separation wall means terminates in a pair of reversing bafiies for directing the fuel-air mixtures back in an upstream direction to the combustion spaces at the outer surfaces of the evaporation walls so that burning which takes place in the combustion spaces will heat the evaporation walls to promote the evaporation of fuel films flowing along the evaporation walls at their inner surfaces.

A typical evaporation type burner for a jet engine or a gas turbine is equipped with evaporation tubes in the combustion chamber to evaporate fuel. Liquid fuel and air enter the tubes, to premix therein, and to ignite while flowing into the combustion zone. Multiple combustion tubes are located along the circumference to equalize distribution of mixed gas, and there are air pipes near the outlets of evaporation tubes to eject slitty air from them and stabilize the flame. Evaporation type burners of this type have defects in that the structure is extremely complicated, the evaporation load characteristic is bad because fuel ejection at the inlets of tubes is not equal along the wall-surface, and so forth.

In other special evaporation type burners liquid fuel fiows as liquid film along the internal surface of the combustion chamber. Evaporation type burners of this type have defects in that the fuel will partially crack and burn because it receives heat directly from combustion gas as well as from a heated plate. Moreover the mixing characteristic is bad because fuel vapour does not premix with primary air, and the structure is complicated -by a large evaporation section because heat needed for evaporation is gained from the counterfiow of combustion gas achieved by swirl vanes.

This invention relates to evaporation type burners which obviate various kind of defects that conventional burners have. A burner according to the invention is equipped with fuel tubes, evaporation plates and guides in a combustion chamber where liquid fuel is burned. The construction is such that the fuel ejected from com-bustion tubes may flow as liquid film along the internal surface of evaporation plates and the air for combustion may ice be supplied from the upstream side toward the downstream side of the evaporation plate. The premixed gas of fuel vapour and air may be directed to curve back toward the upstream side by the guides at the downstream ends of the evaporation plates and may be burned at the back surfaces of the evaporation plates.

The embodiments of the invention will be explained with reference to figures.

FIG. 1 is a section illustrating the units of a burner of the invention, FIG. 2 a plan seen in the direction of A-A line in FIG. 1, FIG. 3 an enlarged view of part of FIG. 1, FIG. 4 a section in the direction of CC line in FIG. 3, and FIG. 5 a section illustrating an example of the case where the number of evaporation plates shown in FIG. 3 is increased.

In the drawings, 1 refers to an external tube of a burner, 2 to an internal tube of a burner, 3, 3 to annular evaporation plates set up concentrically within a burner, 4, 4' to perforated fuel tubes set up annularly along the upstream side of evaporation plate 3, 3' concentrically within the burner, 5 to a flow-separating plate whose downstream ends are bent toward the upstream side to form guides 6, 6, 7 to perforations provided in fuel tubes 4, 4' (FIG. 4), 8 to the inlet of the burner, 9, 9' to inlet bafiies, 10, 10' to vortex fiow combustion gas, and 11, 11' 12, 12 to apertures provided in internal tube 2 to admit air for secondary combustion and dilution.

The fuel supplied into fuel tubes 4, 4 is ejected from perforations 7 into the upstream side of evaporation plates 3, 3' and fiows along the evaporation plates 3, 3 in the form of a film. The air admitted into the burner inlet 8 is separated into two streams by baflies 9, 9'. One stream fiows in annular passages between the external tube 1 and the internal tube 2, and the other flows in annular slit formed between evaporation plates 3 and 3'.

The liquid fuel film flowing along the evaporating plates 3, 3 is heated through evaporation plates 3, 3 by combustion gas at the back surfaces of evaporation plates, which makes the temperature of the fuel gradually increase as it flows, the evaporation finishing instantaneous- 1y by passing the maximum evaporation point and the fuel being mixed with air entering the slit between the evaporation plates 3 and 3. The mixture is directed back toward the upstream direction by guides 6, 6'. Thus the mixed gas ejected in the upstream direction by guides 6, 6' provides the vortex flow of combustion gas 10, 10' and ignites along the back surfaces of evaporation plates 3, 3'. Part of heat becomes the heat source needed for evaporation of liquid film fuel that flows down along the evaporation plates 3, 3.

The number of annular evaporation plates can be chosen freely. FIGURES 1 to 4 show the case of two evaporation plates, and FIG. 5 shows the case when 6 evaporation plates are provided, and the ends of the evaporation plates 3' are bent toward the upstream side forming the guide 6". The mixed gas is ejected toward the upstream side by the guides 6".

Though in every figure only the case of concentric placement of the evaporation plates in the combustion chamber is shown as an example, evaporation plates can be placed radially or in other special forms as a matter of course.

The evaporation type burner of the invention has such a structure that guides which direct the mixed gas of fuel vapour and air back toward the upstream side are in the combustion chamber where liquid fuel is ignited, that the evaporation plates and fuel tube are arranged so that the fuel injected from fuel tubes may form a liquid fuel film flowing along the evaporation plates, and that the premixed gas of fuel vapour and air whose direction is turned toward the upstream side by the guides at the ends of the evaporation plates may ignite at the back surfaces of evaporation plates. In this evaporation burner, fuel flows equally along the evaporation plates, in the form of a liquid film, and is gradually heated by the heat which comes through evaporation plates, without being directly exposed to the combustion gas, to become fuel vapour by evaporating at the maximum evaporation rate point. The primary air that flows along the liquid fuel film and the fuel vapour from the combustible mixture. Then the mixture is directed back toward the upstream side of the primary combustion zone to burn and heat the evaporation plates. The evaporation type burner of the invention has such merits in comparison with conventional burners in that its construction is extremely simple, the evaporation load characteristic is good, the distribution of mixed gas toward circumference is completely equal, and the flame can be stabilized without any special supplementary means. The burner of the invention is superior in that there is no cracking combustion, and the mixing characteristic and combustion load rate are good. Thus the evaporation type combustor of the invention is very effective as a burner for a jet engine and a gas turbine.

Thus, it will be seen that with the structure of the invention the internal tube 2 forms a pair of mutually spaced combustion chamber walls having inner surfaces directed toward each other. The pair of evaporator walls 3 and 3 are situated between these combustion chamber walls, and the latter have their upstream ends connected with the upstream ends of the evaporator walls 3 and 3' to form the combustion spaces where the vortexes 10 and 10 are located. These combustion spaces are closed in the upstream direction by the interconnections between the combustion chamber walls and the evaporation walls, so that the combustion spaces can only communicate with the space which is situated downstream of the evaporation walls 3 and 3'. A separation wall means divides the space between the evaporation walls 3 and 3 so that the pair of fuel supply means 4 and 4' supply fuel to flow along the inner surfaces of the walls 3 and 3" which are directed toward each other, and at its upstream end the space between the walls 3 and 3' communicates with the supply of air. At its downstream end which extends beyond the downstream ends of the walls 3 and 3', the separator wall means carries the reversing baflles 6 and 6' which reverse the direction of flow of the fuel-air mixtures to direct them in an upstream direction along the outer surfaces of the walls 3 and 3', which are directed away from each other, toward the combustion spaces to form the vortexes 1'0 and 10'.

In the embodiment of FIG. 3 the separation wall means is formed by a single wall 5 situated between the evaporation walls 3 and 3'. In the embodiment of FIG. 5, however, it is the walls 3' which form the separation wall means and which carry the reversing bafiles 6". With this embodiment there are an additional pair of inner evaporation walls 3 connected at their upstream ends to the walls 3 of the separation wall means, and this latter means includes the third, central or intermediate wall 5 terminating at its downstream end in the pair of reversing bafiles 6 and 6' :to direct the fuel-air mixture back to a pair of combustion spaces each of which is defined by the upstream ends of the interconnected walls '3 and 3' of FIG. 5. Of course, in this embodiment there are an additional pair of fuel-supply means to supply the fuel to the opposite sides of the central or intermediate separation wall 5.

What we claim is:

1. In a burner, a pair of mutually spaced combustion chamber walls respectively having inner surfaces directed toward each other, a pair of evaporation walls situated between said combustion chamber walls and also being spaced from each other, said evaporation walls respectively having inner surfaces directed toward each other, respectively, and outer surfaces directed away from each other toward said inner surfaces of said combustion chamber walls, respectively, said evaporation walls respectively having upstream ends directed away from each other and respectively connected with said combustion chamber walls to define with the latter a pair of combustion spaces between which said evaporation walls are located, said combustion spaces being closed in an upstream direction and communicating only with the space between the combustion chamber walls downstream of said evaporation walls, separation wall means situated between and spaced from said evaporation walls and having an upstream end communicating with a supply of air which flows on opposite sides of said separation wall between said evaporation walls, a pair of fuel supply means respectively situated on opposite sides of said separation wall means to direct fuel between said evaporation Walls to mix with the air flowing therebetween on opposite sides of said separation wall means, and said separation wall means extending downstream .beyond the downstream ends of said evaporation walls and carrying at its downstream end a pair of reversing bafiles extending laterally beyond said evaporation walls toward said combustion chamber walls for directing the mixture of fuel and air at the opposite sides of said separation wall means back along the outer surfaces of said evaporation walls toward said combustion spaces where the mixture burns to heat said evaporation walls for promoting the evaporation of fuel films flowing along said evaporation walls at the opposite sides of said separation wall means.

2. The combination of claim 1 and wherein all of said walls are cylindrical and coaxial so that said combustion spaces are of an annular configuration, and said reversing bafiies being in the form of channels of U-shaped cross section.

3. The combination of claim 1 and wherein said combustion chamber walls are formed with apertures situated downstream of said reversing 'bafiles, and a pair of exterior walls spaced from said combustion chamber walls and respectively having inner surfaces directed toward said combustion chamber walls to define with the latter spaces through which air can enter into the space between said combustion chamber walls through said apertures.

4. The combination of claim 1 and wherein said separation wall means is in the form of a single wall member situated between said evaporation walls.

5. The combination of claim 1 and wherein said separation wall means includes a pair of spaced separation walls respectively terminating at their downstream ends in said reversing bafiies, a pair of additional evaporation walls situated between said pair of separation walls and having upstream ends respectively connected to upstream ends of said pair of separation walls to define with the latter a pair of additional combustion spaces, and a third separation wall situated between said pair of additional evaporation walls and terminating at its downstream end ina pair of reversing baflles for directing a combustible mixture back to the additional combustion spaces, and additional fuel-supply means communicating with the spaces on the opposite sides of said third separation wall to direct fuel between said additional evaporation walls.

References Cited UNITED STATES PATENTS 2,541,900 2/1951 Williams 6039.7l 2,635,426 4/ 1953 Meschino 6O39.7l 2,720,753 10/ 1955 Sharpe 60---39.7l 2,982,098 5/ 1961 Vickery 60-3971 JULIUS E. WEST, Primary Examiner.

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