JPS591915A - Annular conical air-fuel mixer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the design of burners for combustors used for purposes such as gas turbine engines, heating units, and/or for the vaporization of cryogenic liquids such as liquid nitrogen. .

In such combustors, a liquid fuel, such as oil, is introduced into a primary combustion chamber where it is mixed with air to form a combustible mixture. Typically, a primary combustion air inlet button supplies air to the combustion chamber, where it mixes with the atomized liquid/fuel.

retaining maximum control over the combustion and preventing uneven combustion that could overheat certain parts of the liner or cause it to become so unstable that it occasionally goes out and requires relighting;
A variety of means are used to establish stable flame patterns for this purpose.

In these combustion chambers, swirl vanes are commonly used to swirl the air as it encounters the flow of liquid fuel from the fuel nozzle. The number and size of holes are established as required to properly swirl such secondary combustion air. For an explanation of such a combustion mixer, see Chapter S of the Turbine Engineering Handbook by authors HERBERT R, HAZARD K.
Combustor”. As shown by this author, the art proposes a swirling motion of the air and the generation of a low pressure region at the combustion axis in order to continuously recirculate the flame towards the fuel nozzle. .

However, the need to handle both the tangential and axial directions of flow increases the difficulty in designing such swirling motions, and as a result it is often very difficult to predict the final flame rotation with any certainty. It's difficult. As shown on page 73 of the above-mentioned authors, many different means of solving the problem have been devised in the art.

The above-mentioned difficulty in developing a mixing device that produces a stable flame is due to the fact that a converging cone of primary combustion air is injected into a diverging hollow cone of liquid fuel that is sprayed into the primary combustion chamber by a fuel nozzle. This is greatly reduced by the present invention.

The present invention allows for a low cost design that mixes air and liquid fuel over a wide range of fuel/air mixtures. The flame itself is very stable and is not sensitive to large incoming air flows or pressure instability.

By introducing the secondary combustion air further downstream of the actual flame, flame stability is not affected by changes in the flow of the secondary combustion air.

Since the primary combustion air in the converging cone is uniform, the development of the flame is the turning point that pulls the roots away from the inner wall or surface of the combustor, and thus even the inner surface of such a combustor is made of ordinary copper. In other words, it can be constructed from 3/θ stainless steel of Mr. N, 27 meters (left θ mil), and does not require refractory materials.

With respect to the filler and structure surrounding the mixing zone, the overall cost of manufacturing the combustor itself can be reduced.

Referring first to FIG. 1, a combustor 30 is shown for use with a liquid fuel such as oil. Heat baker 30
is preferably cylindrical in shape, generally 725'
- has an outer shell 32 constructed of stainless steel. A general description of the combustor is provided in the Gas Turbine Engineering Handbook mentioned above.

Within the shell 32 is a liner 34 that is cylindrical and coaxial with the shell and is constructed of relatively thin stainless steel (0.0!r inches thick). , the litchi includes a primary combustion chamber 36 and a secondary combustion chamber 38, in which the hot gas from the secondary combustion chamber 36 is mixed with secondary air to complete the combustion process. .

In the embodiment shown here, air for combustion in the secondary combustion chamber 36 and air for complete combustion in the secondary combustion chamber 38 is provided by a fan (not shown), and the air is connected to the liner 34. Through an annular passageway 40 between the outer shell 32 and the outer shell 32, the air flow serves to cool the liner 34 and the outer shell 32. As shown in FIG. 1, air passes through the annular passage in the direction of arrow 42.

End plate 44 closes off one end of combustor 30 and fits over the ends of liner 34 and shell 32 to confine them. End plate 44
Centrally positioned through the top is a nozzle holder 46 which injects air to, among other things, determine the pattern of fuel distribution of the liquid fuel injected by the fuel nozzle 48 .

Nozzle retainer 46 is more fully shown in cross-sectional view in FIG. 1 and in end view in FIG.
Generally, it has a body 50 with an opening 52, with one end of the opening 52 forming an angled opening 54 at an angle of about 90° about the solid axis of the opening 52, as shown. It is open and the nozzle retainer 46 further has a plurality of radially oriented openings 56 that open into the angled opening 54 . Body 50 has a recess formed therein for receiving a fuel nozzle 48 (not shown in FIGS. 3 and 3). The fuel nozzle 48 is Dε and AVAN C0RPORATIO
It may be of a conventional commercial design, such as that provided by Nozzle Type No. 27770-7;
No. 7770-7 is 7 x 10'Ky/m" r-
λλJKy(/θOpslg) per hour at a supply pressure of
A; Fuel consumption of Olbs, /hr,) (JP4)
is estimated.

The particular fuel nozzle 48 is designed to spray atomized fuel oil in the shape of a widening hollow cone about a solid axis of the cone at an overall angle of S0±50. Opening 56
By passing air through, the liquid fuel will swirl and create a vortex in the secondary combustion chamber 36.

Further, as shown in FIG. 1, the outer surface 5 of the nozzle holding portion 46
7 forms an angle of approximately 30° with respect to the solid axis aK of the nozzle holder, that is, converges into a truncated conical shape at an overall angle of approximately 6θ0 with respect to the solid axis of the nozzle holder. ing.

A circular baffle plate 60 surrounds the fuel nozzle 48 and the nozzle holder 46. The details of the baffle plate 60 are shown in Fig.
and FIG. 3, and FIG. 1 shows a state in which the baffle plate 60 is assembled to the combustor 30. A baffle plate 60 is shown having an interior 62 and a central opening 64. The inner ridge 66 of the annular dish-shaped interior 62 is formed at an angle of approximately 300 degrees l- to the solid axis of the baffle plate 60, or a total angle of 60 degrees in the form of a converging cone.

As shown in FIG. 1, baffle plate 60 is coaxially attached to nozzle retainer 46 and fuel nozzle 48 by means such as bolts 68 secured to end plate 44 by nuts 70 and spacers. 72 is held in place relative to the fuel nozzle 48. In a preferred embodiment, three such bolts 68, spacers 72, and nuts 70 are provided in bolt holes 7 of baffle plate 60.
The holes 76 in the baffle plate 60 are used in conjunction with an incandescent type ignition device (the function of which will be explained below) to hold the baffle plate 60 in a fixed position through the holes 76 of the baffle plate 60.

As can now be seen in FIG. 1, the flow of air for use in the secondary combustion chamber 36 and the secondary combustion chamber 38 proceeds as follows. Secondary air, ie, the air actually used in the combustion of the liquid fuel, passes along the annular passageway 40 and enters the plenum chamber 80 through a plurality of openings 82 in the annular passageway 40.

A plenum chamber 80 is thus formed at the rear of the baffle plate 60, and air from the core solenum chamber 80 can be used for a variety of purposes.

A portion of the air from the plenum chamber 80 is transferred to the nozzle holding portion 46
Such air passes through the radially oriented openings 56 of the fuel nozzle 48 and serves to create a swirling movement for the fuel injected into the primary combustion chamber 36.

Another part of the air from the plenum chamber 80 is transferred to the baffle plate 6
However, the air in the plenum chamber 80 leaks beyond the outer edge 84 of the plenum, providing some cooling of the inner surface of the liner 34 and protecting the liner 34 from direct action or contact by the combustion gases in the combustion chamber 36. The majority of
It passes through the annular conical opening 86 and is used as primary air to provide oxygen for the combustion of the liquid fuel.

As mentioned above, the design angle of the outer surface 57 of the nozzle retainer 46 and the inner rib 7'66 of the baffle plate 60 allows the annular conical opening 86 to form an overall angle of approximately 600 degrees around the solid axis of the fuel nozzle 48. It converges in the direction toward the -order combustion chamber.

The secondary air passes through the plurality of openings 87 to the secondary combustion chamber 38.
is supplied to the combustion chamber 38 and mixed with hot combustion gas in the secondary combustion chamber 38 to complete the combustion process.

Thus, during operation, fuel is injected outwardly into the primary combustion chamber 36 by the fuel nozzle 48 in a diverging hollow conical semi-turn with a total angle of about 730 by 30. The fuel is atomized into droplets by the fuel nozzle 48 in such a predetermined pattern to create a flammable mixture of liquid fuel and air in a zone where combustion actually occurs. The primary air for providing oxygen for the combustible mixture passes through a converging annular conical opening 86 and impinges on the diverging hollow conical nozzle or turn of the liquid fuel, generally in the direction of the arrow in FIG. Form four turns of motion as shown in .

This causes the liquid fuel/air mixture pattern to form a zone of combustible mixture in zone 88, which is a relatively stable, quiet zone protected from the direct flow of liquid fuel by baffle plate 60. Bandwidth. Thus, this band 8
8 includes a mixing side that is easily ignited by an incandescent type ignition assembly 78.

Ignition assembly 78 is high voltage discharge 1! It may be a conventional spark-type ignition device for igniting the liquid fuel-air mixture in zone 88 by a igniter, or as shown, one end secured within a suitably sized opening 92 in end plate 44. Preferably, the housing 90 has a cylindrical shape, with the other end passing through the opening 76 of the baffle plate 60. An incandescent or spark type igniter 94 may be positioned within the cylindrical housing 90 by means such as a threaded engagement to facilitate assembly or removal at location 95. As shown, the igniter 94 includes a high resistance heating wire to create a high enough temperature to ignite the liquid fuel/air mixture in zone 88 within the primary combustion chamber 36,
A commercially available glow plug, such as PION Model CH, is preferred.

Again, once ignited, the flame maintains a very stable position and does not change despite wide variations in the level of fuel flow, as shown by the arrow in FIG. The stable flame glow turns are caused by the primary void being delivered in a converging annular cone and impinging in a uniform pattern around the diverging cone spray of liquid fuel from the fuel nozzle 48.

[Brief explanation of the drawing]

FIG. 1 shows a partially sectional side view of an oil-fired combustor having a fuel/air mixing system constructed in accordance with the present invention. 2 is a side view, partially in section, of a nozzle holder used to hold a fuel nozzle for introducing and atomizing liquid fuel into the combustor of FIG. 1; FIG. FIG. 3 is a partially cutaway sectional end view of the nozzle holding portion of FIG. 2. FIG. FIG. 1 is a side cross-sectional view of the baffle plate used in the combustor of FIG. 1 to create a stable flame/4' turn. FIG. S is an end view of the baffle plate of FIG. 30... Combustor, 32... Outer shell,
34... Rai, Su, 36... - Fire combustion chamber, 38... Secondary combustion chamber, 40...
...Annular passage, 44... End plate, 46.
... Nozzle holding part, 50 ... Main body, 5
2.54.56...opening, 48...
・Fuel nozzle, 60... baffle plate,
62...Annular dish-shaped interior, 64...Central opening, 66...Inner lip, 6B.
...Bolt, 70...Natsuto, 72
...Spacer, 74t76 ...hole, 80 ...Blenheim chamber, 86 ...
Annular conical opening, 88...band, 78.
...Ignition assembly, 90...Housing,
94...Ignition device. IG, 4 FIG, 5

Claims (1)

[Claims] /) A method for creating a stable flame within a combustion chamber, comprising: spraying liquid fuel into the combustion chamber in a hollow conical pattern having a predetermined angle; The process of injecting into the combustion chamber in an annular-conical pattern that converges in the same direction as the injection flow, and the primary air conditioner, liquid fuel, in an annular-conical pattern that converges to create a zone of flammable mixture of liquid fuel and air. igniting the combustible mixture in the zone to produce fuel. 2) said directing a converging annular cone of primary air to the axis of said hollow cone of atomized liquid fuel;
2. The method of claim 1, further comprising coaxially aligning the axis of the air annular cone. 3) In a device for mixing liquid fuel and primary air in a combustion chamber, a spray of liquid fuel is directed toward the combustion chamber in a hollow conical /'P turn that widens in the direction of flow, and in a predetermined manner. a fuel nozzle arrangement with a diverging angle, and a secondary air directed at a predetermined direction in the direction of flow for impinging the secondary air on said spray of liquid fuel to form a zone of flammable mixture of liquid fuel and primary air. and an ignition device that selectively ignites the flammable mixture of liquid fuel and air within the combustion chamber. Device. g) A combustion device, which has a cylindrical combustion chamber and an outer surface that converges at a predetermined angle toward the combustion chamber, and sprays liquid fuel into the combustion chamber in a hollow conical knot that widens at the end. a nozzle device at one end of the chamber; and a circular baffle plate coaxial with and surrounding the nozzle device, the baffle plate being disposed between the baffle plate and the nozzle device and extending into the combustion chamber. a central opening formed by a lip with an inner surface converging at a predetermined angle toward said combustion chamber to form an annular conical opening converging at a predetermined angle toward said combustion chamber; Primary air is introduced through the annular conical opening to impinge on the liquid fuel in the diverging hollow cone to form a zone of combustible mixture of liquid fuel and primary air within the combustion chamber. A combustion device comprising: an ignition device for igniting the zone containing the combustible mixture to combust the liquid fuel within the combustion chamber. ! r) Combustion device according to claim 1, characterized in that the annular conical opening converges in the direction of the combustion chamber at a total angle of about 600.