FR2562212A1 - DEVICE FOR SUPPLYING A PULSATORY FUEL AND COMBUSTION COMBUSTION CHAMBER - Google Patents

Abstract

DEVICE ALLOWING TO SUPPLY A PULSATORY COMBUSTION CHAMBER WITH FUEL AND OIL. IT INCLUDES A MANIFOLD FOR THE OXIDIZER AND INJECTION ORIFICES OF THE SAID OXIDIZER ARRANGED SO THAT THE COMBURANT IS INJECTED IN THE MANIFOLD WITH A VIRTUAL MOVEMENT. APPLICATION TO PULSATORY COMBUSTION.

Description

The present invention relates to a device for feeding a

pulsating combustion chamber

in fuel and in oxidizer.

  The pulsating combustion of a mixture of oxidizer and fuel in a chamber requires introduction

  in this chamber of the mixture intermittently.

  There are several possibilities to perform this operation. Fuel can be introduced continuously

  and the oxidant alternately or mix the two

  and introduce melargege-sequentially. The provision

  According to the invention, the invention makes it possible to

  continuously and inject the oxidizer sequentially.

  When the fuel is a liquid hydrocarbon such as home heating oil and the oxidant is air, the choice of continuous fuel injection raises certain problems which may be incompatible with the long-term use of the pulsating combustion chamber. problems, the propensity to fouling of the feed device is mainly due to the time intervals during which the air is not injected, the

  fuel combustion is in air defect.

  In known devices such as that described in the patent application filed by PCT under the number 81 01454 Starting Method and device for combustion apparatus ", the air is injected into a collector which surrounds the fuel injection head. Valves stop the injection of air when the pressure in the chamber rises.This device has several drawbacks that promote the clogging of the chamber.In particular, the injection head is not in contact the injection head tends to heat up, especially because of the large volume available between the combustion chamber and the valves, the flue gases that are pushed towards the valves during the pressure rise in the

  chamber, may reach the level of the injection head

  tion, warm it and thus increase its fouling.

  In addition, in this device, the introduced air jet is virtually vertical. There is therefore a breakeven point between the vertical and downward movement of the air and its movement

  vertical and ascending before closing the valves.

  During this dead point, which occurs twice per cycle, the walls of the chamber in which the mixture is made are no longer swept by the gas mixture, which is conducive

to fouling.

  The invention provides a device which makes it possible to overcome these disadvantages and to obtain combustion under

  a pulsating regime without noticeable occurrence of fouling.

  For this, it concerns a feeding device of a

  combustion chamber with combustion and fuel

which essentially comprises:

  a fuel injection means,

  - Oxidizing injection means, said means surrounding said injection head and being provided with valves for the intermittent injection of said oxidant according to the variations of the pressure inside the chamber, - an intermediate channel, located in amon-of the combustion chamber and in which is performed'Ia larger

  part of the mixture of fuel and oxidizer.

  According to the invention, the oxidant injection means comprise at least two oxidant injection channels opening through said valves in an annular manifold which comprises at least one upper wall and one lower wall and at least a part of which from the bottom wall has a shape convergent towards said intermediate channel, said oxidant injection channels being inclined with respect to the axis of the fuel injection means so that the oxidizer is imparted a continuously accelerated vortex movement under the combined action of the shape of the collector

  and the inclination of said oxidant injection channels.

  According to another preferred feature, the fuel injection means is constituted by a head

  injection located entirely inside the manifold.

256221.2

  This leads preferentially to the upper level

of the intermediate chamber.

  The advantages and other features of the invention will appear more clearly on reading

  the following description of an embodiment, descrip-

  FIG. 1 is a fragmentary sectional view of one embodiment, FIG. 2 is a view of a detail of an embodiment of the invention, and FIG. part of the oxidizer injection device; FIG. 3 is a sectional view of a first embodiment of a valve of FIG. 1; FIG. 4 is a sectional view of a second embodiment. 5 is a section along the axis WVV of FIG. 4, FIG. 6 represents a detail of a variant of FIG.

embodiment of the invention.

  Figure 1 is a partial sectional view of a device (1) according to the invention. It is constituted by a

  body (2) mounted on the neck (3) of a combustion chamber (4)

  pulsation. The body (2) has two parts, an upper plate (5) and a valve door part (6). These two pieces are parts of revolution, symmetrical

around an axis (8).

  The upper plate (5) is engaged in a housing (9) which defines with it a chamber (10) for the admission of air. It comprises a threaded central bore (11) and bores such as (12). The bores (12) are cylindrical and their axes are inclined with respect to the axis of revolution (8) and with respect to the diametrical planes of the plate as will appear below. In its lower part, the plate (5) is provided with a central bore (20) of large diameter. The bottom (21) of this bore has the shape of a surface of revolution (22) whose section by a diametral plane is rounded and a conical surface (23)

  in extension of the surface of revolution (22).

  The valve member (6) has a central bore (30) comprising a conical portion (31), a flared (32) and convergent portion, and a wall (33). Curvature

  part (32) is circular and the wall (33) of the

  sage (30) is vertical in immediate proximity (34)

a bore (45).

  In the upper part of the support part, the central bore (30) defines with the upper wall of the part (6)

  a circular step (37) resting on the flat surface (23).

  The flap piece is attached to the neck (3) by a series of five bolts such as (40) and has a pair

  ignition electrodes (41) and (42).

  The device (1) is held in place on the neck (3) by means of threaded tie rods (75) which are screwed into nuts (77) welded to a support seat (76) itself welded to, collar (3). In this device, represented in FIG. 1, all the parts are metallic, except the valve door part, which is made of a plastics material having good resistance to

  heat transfers by convection.

  The device thus represented operates from the

following way.

  First of all, a conventional stage of initiation of the pulsating combustion is carried out and for this purpose

  injects the air through the bores (12) into the manifold (100).

  This manifold (100) is defined by the wall (21) of the bore (20), the walls (31), (32) and (33) of the bore (30) and the bore (45). This injection is made using a fan not shown. The combustion is initiated by a high voltage ignition produced by the electrodes (41) and (42). After the first explosion, when the pressure in the chamber (4) and subsequently in the manifold becomes greater than the air injection pressure, the valves (90) seal the injection ports (12). The fan is used until the pulse cycle is fully established. In steady state, the electrodes

are no longer used.

  When it is injected into the manifold (100), i.e., when the valves (90) are open, the air moves in a continuously accelerated swirling motion. This acceleration is due to the convergent shape of the lower wall of the collector which is for this purpose continuously convergent. The vortex movement is due to the inclination of the axes (110) of the bores such as (12). Referring to Figure 2, we see that these axes (110) are inclined firstly relative to the plane of the workpiece (5), but they are also inclined relative to the radial planes (111). The angle represented in FIG. 2 can be between 90 and 45, while the angle e represented in FIG. 1 is between 45 and 70 ° C., these values being given for illustrative purposes only, since the creation of the swirling movement also depends on the

collector form.

  The fuel is injected continuously by a nozzle or injection head (115) which is screwed into the bore (11). The spraying cone of the injection is such that the impact of the drops of fuel is mainly below the bore (45), that is to say in the intermediate channel,

  corresponding to the inside of the neck (3).

  The swirling motion of the air is maintained

  throughout the collector as well as in the intermediate channel.

  It can be considered that the intermediate channel constitutes the mixture zone of the fuel and the oxidant, although it is obviously very possible that a part of the mixture already takes place in the lower zone of the coil.

  or, on the contrary, in the combustion chamber (4).

  The fact that the air is injected into the collector (100) with a vortex movement has the advantage

particular following.

  During the recompression of the flue gases and the closure of the valves (90), the injected air remains in motion even if the vertical component of its speed changes direction since the tangential component will never be zero. Thus the lower wall of the collector (100)

  will always be swept and cooled by a draft.

  This favorable effect is further improved by the low volume of the collector and therefore by the low air mass

  likely to be compressed by the rise of flue gases.

  The small volume of the collector is mainly due to the convergent shape of its lower wall. This volume can be further reduced by changing the shape of the

upper wall.

  In the device shown in Figures 1 to 3, it was mentioned above that the valve door part was a thermally insulating material. This has the effect of limiting the heating of the injection head. But we can

  also plan to make this piece of metal and

  put between it and the intermediate channel an insulating disc that will then prevent heat transfer upwards, the insulating disc extending over the entire height

of the bore (45). -

  FIG. 3 shows the detail of the

  placing the valve (90) on the valve door part (6).

  The valve (90) is constituted by a flat ring (120), deformable, of width greater than the width of the bores

  (12). It is held in place between the bottom (21) of the

  wise (20) and the conical wall (31) of the valve door part

  (6) on which it is supported by its outer diameter.

  The height of the circular step (37) is greater than the thickness of the flat ring so that the latter can move between a low position corresponding to the opening of the valve and a high position corresponding to its closure. As the wall (31) has a conical shape at the level of the ring, the lower face thereof is not

  never completely pressed against the wall (31). THE INCREASE

  pressure inside the manifold (100) is therefore transmitted to the underside of the ring, which

causes the shutter to close.

  The valves shown in FIGS. 4 and 5 proceed from another principle since they are individual valves (130) made in the form of pellets (131) which are movable in translation inside centering studs (132). ), (133) and (134) attached to the plate (5) by being force-fitted in blind bores. According to this embodiment, the wall (31) of the door piece

  valve (6) is horizontal vis-à-vis the pellets (131).

  In order to allow the closure of these valves during the pressure increase in the manifold (100), a groove (135) is formed in the valve door part (6) vis-à-vis each valve. As is more particularly visible in FIG. 5, the groove is oriented along an axis (150) which is symmetrical to the axis

  (110) with respect to the diameter (111).

  As shown in FIG. 6, the bore (12) can be replaced by a series of coaxial bores (140), each having the same orientation as that defined for the axes (12) with reference to FIG. solution

  improves the sealing of the valves.

  The invention is not limited to the modes of

  described, it encompasses all variants, so much so that shapes and

  than the choice of materials used.

  Thus, for example, the bore (45) shown is diverging towards the intermediate channel. But we can expect to achieve it either perfectly cylindrical or with a

  convergent form towards the intermediate channel.

Claims (8)

  1 - Device for supplying oxidant and fuel to a pulsating combustion chamber, comprising a fuel injection means, means for injecting the oxidant surrounding said injection means of the fuel.   fuel and being fitted with valves allowing the injection   intermittent operation of said oxidant according to the variations of the pressure inside the combustion chamber, an intermediate channel located upstream of the combustion chamber and in which is carried out the largest   part of the mixture of fuel and oxidizer,   characterized in that the oxidant injection means   comprise at least two injection channels of the fuel   rant opening through said valves in an annular manifold comprising at least an upper wall and a bottom wall and at least a portion of the bottom wall of which has a shape convergent towards said intermediate channel, said channels being inclined relative to the axis of the oxidant injection means so that the oxidizer is imparted a continuously accelerated swirling motion under the combined action of the collector the inclination of said channels.   2 - Device according to claim 1, characterized in that the lower wall of the collector has a continuously convergent shape in its central part and a   cylindrical shape in its downstream part.   3 - Device according to claim 1, characterized in that the fuel injection means is constituted by an injection head located entirely inside. of the collector.   4 - Device according to claim 1, characterized in that the collector opens at the upper level of the channel intermediate.   - Device according to claim 1, characterized in that the valves are constituted by a flat ring whose at least the upper face is deformable, said ring being held between said upper walls and   bottom of said annular collector.   6 - Device according to claim 5, characterized in that said bottom wall is conical at least in its part opposite the ring. 7 - Device according to claim 1, characterized in that the valves are constituted by movable pellets between the upper wall and the lower wall said annular collector.   8 - Device according to claim 7, characterized in that the pellets are guided by pins secured together at least one of said walls.   9 - Device according to claim 1, characterized in that each of said channels is constituted by a plurality   parallel elementary channels with the same inclination   naison relative to said axis of the injection head.   - Device according to claim 7 or 5, characterized in that said collector is provided with at least one groove on its bottom wall, each groove being   located opposite said valves.   11 - Device according to claim 1, characterized in that the lower wall of said collector is made, at least partially, of a thermally insulating material. 12 - Device according to claim 1, characterized in that said channels are located in the upper part of the annular collector. 9 sheets Company Anonymous says: ELF AQUITAINE NATIONAL SOCIETY and MARECK B.V.