US3558119A

US3558119A - Device for the injection of liquid fuels into blast furnaces

Info

Publication number: US3558119A
Application number: US781715A
Authority: US
Inventors: Roger Demalander
Original assignee: Pont a Mousson SA
Current assignee: Pont a Mousson SA; Centre de Recherches de Pont a Mousson
Priority date: 1967-12-08
Filing date: 1968-12-04
Publication date: 1971-01-26
Anticipated expiration: 1988-01-26
Also published as: BE722464A; DE1813217A1; LU57434A1; CH506023A; FR1559679A; ES360485A1; NL6817509A; GB1205098A

Abstract

Liquid fuel injecting device for in particular a blast furnace comprising, in combination with the wind blowing nozzle and the tuyere, refractory elements arranged on a circle between the downstream end of the nozzle and the upstream end of the tuyere where they constitute the neck and divergent part of a Venturi structure, the convergent part being constituted by the nozzle. A liquid fuel supply conduit is carried by the nozzle and terminates in a sprayer disposed in the vicinity of and on the axis of the Venturi neck. Means are provided for imparting a gyratory motion to the wind blown by the nozzle.

Description

United States Patent [72] Inventors Roger Demalander, deceased, late of l 56] References Cited Mamie i :-"& l":; UNlTED STATES PATENTS l l ega 2 3,166,621 1/1965 Carlson 266 41 Maldreres, France 211 App]. N0. 781,715

[54] DEVICE FOR THE INJECTION OF LIQUID FUELS INTO BLAST FURNACES 18 Claims, 5 Drawing Figs.

[52] US. Cl 266/41, 75/42; 110/1825; 122/6.6 [51] Int. Cl C21b 7/16 [50] Field of Search 266/34.1,

Primary Examiner-Gerald A. Dost Attorney-J. Delattre-Seguy ABSTRACT: Liquid fuel injecting device for in particular a blast furnace comprising, in combination with the wind blowing nozzle and the tuyere, refractory elements arranged on a circle between the downstream end of the nozzle and the upstream end of the tuyere where they constitute the neck and divergent part of a Venturi structure, the convergent part being constituted by the nozzle. A liquid fuel supply conduit is carried by the noule and terminates in a sprayer disposed in the vicinity of and on the axis of the Venturi neck. Means are provided for imparting a gyratory motion to the wind blown by the nozzle.

PATENTED JAN26 I97! SHEET 2 0F 2 LEGAL ADMINISTRATRIX 1 /,0MM0-'J,,

/V/|/7 0 K ROGER DEMALANDER,DECEASED B JACQUELlNE DEMALANDER,

/nay DEVICE FOR TIIE INJECTION OF LIQUID FUELS INTO BLAST FURNACES The present invention, made in the Departments of the Applicant under the direction of Mr. Roger Demalander deceased on May 4, 1968, relates to the injection of large amounts of fuels into furnaces for heating, melting or reoccing, and in particular cupola and blast furnaces in particular for reducing the coke consumption.

More particularly, the invention relates to the injection of liquid fuels under high pressure, equal to at least bars, and in particular but not exclusively for blast furnaces into which a very hot wind (at a temperature distinctly higher than 800 C.), which may be enriched with oxygen, is blown.

Owing to the high rate of injection, that is, the large amount of fuel injected, a small excess of air is employed. This excess is less than 70 percent of the stoechiometric combustion air, that is, the amount of air theoretically necessary for a neutral combustion, and there is employed a wind which is very hot, for example at 1000 C. Very high temperatures of combustion, exceeding 2000 C., result from these two characteristics. Consequently, the usual construction of wind-blowing tuyeres, usually having a double wall of copper cooled by circulation of water and noninsulated, is no longer sufficient.

Owing to the high injection rates for the liquid fuel, which must be completely burnt before passing into the charge of the blast furnace, satisfaction is not achieved by spraying this fuel near the outlet of the tuyere and of the burner in the small coke-free space in front of the tuyere. Indeed, as this free space is small, variable in shape and traversed by irregular and nonguidable gaseous currents, the combustion would be in this case incomplete, with formation of soot which clogs the charges and results in irregularities in the descent and passage of the gases in the shaft of the blast furnace.

The object of the invention is to provide a device for injecting liquid fuel at a high rate into a shaft furnace inside a conduit formed by the assembly in end-to-end of relation anair blowing nozzle and a tuyere, this device transforming the nozzle tuyere assembly into a high intensity combustion chamber which is adapted both to the requirements of the shaft furnace and to the very high temperatures of the combustion with air at more than 800 C.

The injecting device according to the invention comprises in combination with the nozzle and the tuyere refractory elements disposed in a ring between the downstream end of the nonle and the upstream end of the tuyere where they form the neck and the divergent part of a Venturi whose upstream convergent part is formed by the nozzle; a fuel supply conduit carried by said nozzle and terminating in an injector located in the vicinity and on the axis of said neck; and means for imparting a gyratory motion to the wind blown through the nozzle.

This device injects the liquid fuel at high pressure so as to achieve a very fine spray which is dispersed rapidly in the gyratory motion of the flow of the hot wind whose temperature ensures a rapid vaporization and ignition of the fuel.

This device ensures an efficient dispersion, a sufficient stay of the fuel droplets, notwithstanding a high axial velocity, and also creates a recirculation zone which is roughly stationary (defined hereinafter) and permits hitching or catching the flame, owing: to means imparting to the flow of the wind, a gyratory motion; to the convergent nozzle which increases the velocity of the wind in the region of the injection; and to the great widening of the conduit immediately following on the convergent noule, this widening spreading the gyratory flow, while retarding its axial speed and thus increasing the length of the helical path of the droplets driven along and creating said axial recirculation zone which is practically stationary and localizes the catching of the flame.

According to other features of the invention, the wind flow is caused to gyrate by a diaphragm provided with an oblique fin structure or by a spherical nozzle from which opens out tangentially a wind supply conduit having great inclination relative to the axis of the aperture of the nozzle in contact with the tuyere.

FIG. 3 is an elevational view of a modification of this elev ment;

the device according to the invention, and

FIG. 5 is a diagrammatic sectional view of another modification of the invention.

In the embodiment shown in FIGS. 1 and 2, the invention is applied to the shaft or hearth of a blast furnace of which the wall C and one of the blast tuyeres 1 having a conical water jacket and an axis X-X, have been shown. The device according to the invention will be described in moving from the downstream towards the upstream end of the wind or blast conduit.

The tuyere l is provided internally with a refractory lining 2 which terminates short of the large diameter end of the tuyere. The latter is traversed in the vicinity of its large end by a lateral cold air blast conduit 3 whose outlet is near the large diameter end of the lining 2.

The upstream end of the tuyere l is applied to a thick flange 4 which serves as a support for a ring of refractory elements 5. This ring is maintained between the flange 4 and the end face of the refractory lining 2. It has an inner profile which is divergent in the form of a trumpet whereas its outer face has a recess 6 which forms with the tuyere 1 an annular chamber with which the cold air conduit 3 communicates. The ring of elements 5 is also provided with oblique slots 7 which are equally spaced on the periphery and have their outlets flush with the large diameter end of the refractory lining 2 of the nozzle on the joint face between this ring and said refractory lining. The slots put the recess 6 in communication with the cavity of the tuyere 1 so as to conduct cold air along the lining 2.

The flange 4 also has a concave part spherical bearing face 8 adapted to serve as a housing for the part spherical convex nose of a noale 9.

The flange 4 and the rings 5 form a connection between the tuyere and the nozzle 9.

This nozzle, which is interposed between the tuyere l and a bent conduit D termed a blowpipe, is a tubular coupling having a generally frustoconical shape of axis X-X and convergent towards the downstream end. It comprises, as known, an outer case 10 of sheet metal and a refractory lining 11. It is reinforced at both ends by metal end elements, one end forming the mouth 12 applied to the part spherical bearing face of the flange 4 of the tuyere and the other constitutinga concave part spherical socket in which the end of the blowpipe D is applied.

The nozzle 9 is traversed obliquely by a liquid fuel injection conduit 14 and the latter is straightened at its downstream end so as to be on the axis X-X on which it terminates in a mechanical sprayer 15 which ejects the liquid fuel. This highpressure sprayer is, for example, of the type corresponding to Diesel engine injectors or jets for starting up rotation.

The metal nose 12 of the nozzle is hollow and cooled by a circulation of water in an annular chamber 16; it is moreover provided internally with refractory material which can be an extension of the lining ll of a special sleeve 17. This refractory lining is flush with the aperture of the ring of elements 5 and also connects the lining 11 to this ring.

The conduit formed by the cavity of the conical refractory lining 11, the sleeve 17 and the ring of refractory elements 5, constitute a Venturi or convergent-divergent structure whose convergent part is the lining 11, the neck, the sleeve 17 and the divergent part, the ring of elements 5. The sprayer 15 for injecting the liquid fuel is located on the upstream side of the FIG. 4 is a diagrammatic sectional view of a modification of connection of the neck to the divergent part formed by the ring of elements 5 (relative to the direction of the blowing of the wind).

lnserted in the upstream end of the nozzle 9 is a diaphragm E. This diaphragm comprises an annular blading 13 around a center hub 19 having an axis X-X. The blading 18 comprises curved blades or fins inclined relative to this axis and overlapping one another. The hub 19 is hollow and an axial tube 20 extending therethrough enables the tuyere nozzle assembly to be viewed.

The diaphragm E, which is exposed only to the temperature of the wind, can be of refractory steel (for a wind of 800" l 5 50 C.) and of refractory ceramic (for a wind of l l50 1 300 C.).

The lining ll of the nozzle 9 is only exposed to the same temperatures and can be of clay or silico-aluminous concrete of good quality.

The refractory sleeve 17 in the neck of the convergentdivergent structure, the ring of refractory elements 5 and the lining 2 of the tuyere l are exposed to the radiation of the flame of liquid fuel with a slight excess of air and wind at more than 800 C. and are thereafter exposed to temperatures which could reach and exceed 1900 C. These pans are for example of super-refractory material having more than 95 percent of alumina or aluminozirconia or zirconia.

The refractory parts 2 and 17 can be made of the previously indicated grades.

The device operates in the following manner:

The nozzle is fed with very hot wind at a temperature of at least 800 C.

The tuyere l is energetically cooled by a circulation of water maintained at high pressure so as to preclude any vaporization. The same is true of the nose l2 of the nozzle 9.

The wind blown in the conduits 3 has a temperature of 150 C. and an absolute pressure of the order of L 6 bars.

The hot wind blown in the nozzle 9 is caused to rotate by the blades of the blading 17. It produces a whirlwind t shown by the dotted line. This whirlwind spreads in the long convergent conical zone of the nozzle 9 and encounters the jet of liquid fuel sprayed at a high pressure exceeding bars.

The divergent part consisting of the ring of elements 5 has for effect to radially spread at l the helical flow of the wind with formation of an axial recirculation or return zone 2, that is, a zone in which the air-fuel mixture returns in a return current in the upstream direction owing to the suction created on the axis by the radial spreading of the helical flow. This recirculation zone is stationary.

The fuel, which is very finely atomized by the sprayer 15, forms a cone of very fine droplets c which, on the periphery of this cone, are driven along in the very flattened gyratory movement I of the very hot air issuing from the divergent part formed by the ring of elements 5, with the result that there is an intense mixing and a rapid vaporization. The center part of the cone 0 of droplets is in the axial recirculation zone 2 and a zigzaging and practically stationary ignition front i is created near the downstream end of this zone and catches on the flame f at the entrance of the tuyere 1 immediately following on the divergent part formed by the ring of elements 5. Thus, the best combustion conditions are achieved for the liquid fuel injected by way of the conduit 14.

Good performance of the blast furnace requires: a complete combustion without soot of the injected liquid fuel which must be completely burnt within the tuyeres, a high flow of the wind or of the wind to which is added fuel fumes so as to ensure the distribution of the wind fumes mixture throughout the section. of the shaft. This flow is usually 40 Nm/s. (40 normal rn. per second, that is, 40 m. of gas measured at 0 C. at a pressure of 760 mm. of mercury). This flow is therefore 93 m. per second at 1000" C. under a pressure of 2 absolute bars, or even slightly more.

The period of stay of the wind or of the wind fumes mixture in a tuyere, such as tuyere 1 not exceeding 1 m. in length, is of the order of one-hundredth of a second or less than this value.

The time for combustion is therefore very short. Moreover, a high rate, that is, a large amount of liquid fuel injection leads to high liquid fuel flows in a section of the tuyere that it would be desirable not to increase in order to limit losses of heat of the water-cooled walls and adapt the device according to the invention without modification of the parts on which the tuyeres are supported.

The combustion rate (in therms/hour given off per cubic meter of volume available for combustion) is therefore very high.

The flame temperatures, owing to the fact that the wind is at high temperature, are also very high.

The advantages resulting from the invention are the follow- Owing to the use of the high-pressure sprayer 15, the fuel is sprayed in very fine droplets which are easy to vaporize by mixture with very hot air and radiation.

Owing to the blading 18 having inclined blades, a gyratory flow is created which increases the length of the path of the air and the turbulence in the tuyere 1. This increases notably the rate of vaporization of the fine droplets of liquid fuel and the rate of mixture with the air of the combustible vapors produced, whence the obtainment of a high combustion rate.

Owing to the combination of the parts 11-17-5 constituting the convergent-divergent structure, with the tuyere l, and owing to the center obstacle produced in the neck 17 by the sprayer 15, there is produced in the gyratory flow created by the blading 18 and highly divergent at 5, the practically stationary recirculation zone 1 where the fuel stays sufficient time for a complete combustion. This zone of recirculation thus provided on the axis of the tuyere 1 ensures the heating by radiation of the neighboring combustible fractions and produces a stable hitching of the flame f without material support.

Owing to the refractory elements 17, 5 and 2:

The inner face of the wind conduit is maintained hot with the result that a radiation favoring the rapid vaporization and the rapid combustion of the liquid fuel is produced.

Heat losses of the wall are limited.

Further, by the use of high-pressure water for cooling the tuyere l and of the nose 12 of the nozzle 9, a very high heat flux can be absorbed without danger of calefaction.

Relatively cold air is introduced by way of the conduit 3, this air being compressed under a pressure of the order of l- 6 relative bars, in a small flow, owing to the small diameter of the conduit 3, the small section of the annular recess 6 formed on the periphery of the refractory elements 5, and the small section of the outlet slots 7. This introduction of cold air along the lining wall 2 in the region where the divergent flow touches the lining 2, protects this lining from excessive local heating.

Thus, the tuyere l constitutes owing to the invention a veritable combustion chamber having a high heat output.

The diaphragm E having the blading 18 is sufficiently remote from this chamber not to be liable to deterioration by excessive temperature. Being of molded refractory steel, it is easily able to withstand the temperature of the wind which can be of the order of 1000-1 C.

Finally, owing to outer shapes and dimensions which correspond to those of tuyeres and nozzles of known type, the device according to the invention is applicable to existing installations provided a few relatively unimportant changes are made. The advantages of these arrangements (for example absorption of the expansions and easy dismantling) are retained.

FIG. 3 shows a modification of the element for causing the wind to gyrate. The hub 19 of the diaphragm having the blades 18 is solid and has a roughly shell shape having a domeshaped upstream end and a downstream end which tapers in the form of an ogive.

Whereas FIGS. 1 and 2 show the adaptation of the invention to an existing wind blowing device, in the embodiment shown in FIG. 4 the invention is applied to the case of the construction or the repairing of a blast furnace. In this case, it is desirable to still further improve the conditions of combustion and assembly rather than be limited to the adaptation of an existing installation.

This is why the embodiment shown in FIG. 4 provides a construction which is shorter in the direction of the axis X-X and wider in the diametral direction.

In this modification, a tuyere l" in the shape of a bulb which is substantially shorter than the tuyere l and substantially wider than the latter in its rear part, is provided. A small nozzle 9 which is substantially shorter than the nozzle 9 is also provided owing to the fact that the liquid fuel supply conduit is also modified. The liquid fuel conduit 14 is indeed bent and extends through the wall of the nozzle at a great angle of inclination in the neighborhood of a right angle relative to the axis XX. This enables the axial overall length to be reduced. Further, this conduit terminates in a sprayer l5 having a widened injection nose which is brought substantially nearer the ring of the refractory elements 5 since it is located roughly in the region of the Venturi neck formed by the nose 12 of the nozzle. The sprayer l5" occupies a large part of the section of the neck (about one-sixth to one-fourth of the section). These proportions moreover correspond to those in the foregoing embodiment.

Instead of having a diaphragm having blading 18 mounted at the upstream end of the nozzle 9, there is provided a diaphragm E having blading l8 brought close to the nose 12 of the nozzle. In this case, as the diaphragm E is nearer the combustion zone in the tuyere I, it is cooled by the same circulation as the nose 12 of the nozzle. The cooling passageways have not been shown in FIG. 4 which is diagrammatic.

Owing to the bulb shape of the tuyere I", there is obtained a gyratory annular flow of the atomized fluid air fuel mixture) with a larger stationary central zone 1 than in the embodiment shown in FIG. 1, whence an improved catching of the flame. Further, as the tuyere is more compact it has a shorter overall length. Heat losses are smaller since the bulb shape of the tuyere approaches a spherical shape. The flow of the fluid is spread over a larger diameter and consequently the time of combustion is longer, whence the possibility of burning a larger amount of liquid fuel for a given tuyere section and consequently, reducing still further the coke consumption. Owing to the modification of the fuel conduit 14, the noule 9 is itself shortened. There is consequently an advantageous limitation of heat losses by a reduction in the dimensions of the circular assembly and of the descending hot wind conduits. Owing to the assembly of the diaphragm E, having blading 18 at the nose 12 of the nozzle 9, this diaphragm acts as a support for the sprayer l5 and thus centers the latter more precisely with the result that there is an improved mixture of fuel with the blown air. The cold air supply conduit 3 can in this modification be connected to the flange 4 of the tuyere 1.

According to another modification shown diagrammatically in FIG. 5, the device according to the invention is made even more compact in the axial direction and the diaphragm is dispensed with. The rotation of the air achieved previously by blading having inclined blades (axial rotation) is achieved in this embodiment by a tangential supply.

Thus, this embodiment comprises a nozzle 1" in an even more accentuated bulb shape, that is, a shape which is wider and shorter than the bulb shape of the nozzle 1. Adapted to the rear face of this nozzle, which is protected by the refractory lining 2, is a connection 4" performing the same function as the flange 4 but having a substantially greater diameter. This connection is hollow and water cooled. Adapted thereto is a refractory ring 5'' consisting of internally profiled or shaped elements having a divergent trumpet inner shape and connected to the refractory lining 2 of the tuyere. Oblique slots 7 are provided on the ring. They communicate with the interior of the tuyere close to its refractory lining 2. Lateral cold air supply conduits 3 lead to the slots. In this way, cold air is injected into the zone of impact of the flow on the lining 2 of the tuyere.

Adapted to the rear face of the tuyere I", that is, inthe socket of the connection 4, is a nozzle 9 having a generally part spherical shape and a reinforced nose 21 which is also part spherical but uncooled by water. Indeed, the cooling is now unnecessary owing to the remoteness of] said nose from the combustion chamber of the tuyere due to the large diameter of the rear face of this tuyere and owing to the protection of the nose by the water chamber of the connection 4". The nozzle 9" comprises a wind supply pipe or nozzle 22 having an axis Y-Y which is highly inclined relative to the axis X--)( at an angle in the neighborhood of this substantially reduces the overall length. This pipe 22 is tangential to the cavity of the nozzle which is provided with a refractory lining 11. Preferably, the pipe terminates in a flange 23 having a part spherical connection which facilitates the adaptation of the wind supply conduit (not shown).

Instead of a fuel supply conduit which is bent or inclined relative to the axis )(X, there is provided a very short conduit 14" which terminates in a sprayer 15" located in the region of the neck of the Venturi. The conduit 14" is centered by a support 24 fitted in an axial pipe 25 of the nozzle. This centering is easily achieved and excellent owing to the short length of the conduit 14 and the shape of the nozzle.

Owing to the part spherical shape of the nozzle 29 and owing to the orientation of the pipe 22, the hot wind blown at high speed encounters the part spherical wall of the refractory lining of the nozzle and is driven in rotation in accordance with a whirlwind t shown in dotted line which moves nearer to the axis X-X in the direction of the neck of the Venturi. A still more intimate mixture of air and liquid fuel is thus achieved.

The arrangement of the assembly is simpler than that of the foregoing devices since the bladed diaphragm can be dispensed with and it is consequently stronger and results in less pressure losses.

Although specific embodiments of the invention have been described, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

Although the invention has been described as applied to a blast furnace, it is also applicable to a cupola furnace.

Iclaim:

I. A device for injecting liquid fuel into a shaft, and in particular into a blast furnace, said device comprising in combination a wind blowing nozzle and a tuyere in coaxial relation, refractory elements assembled in the form of a ring between the downstream end of said nozzle and the upstream end of the tuyere, relative to the direction in which said wind is blown, where they constitute a neck and a divergent part of a Venturi structure having upstream convergent part formed by said nozzle; a liquid fuel supply conduit carried by said nozzle and terminating in an injector located in the vicinity and on the axis of said neck; and means for imparting a gyratory motion to the wind blown through said nozzle.

2. A device as claimed in claim 1, wherein said tuyere has a wide upstream entrance and said ring of refractory elements has a divergent internal profile in the form of a trumpet which is connected to said wide entrance of said tuyere.

3. A device as claimed in claim 1, comprising a refractory internal lining having large diameter upstream end and disposed in said tuyere, oblique slots which open out close to said large diameter end of said refractory lining and located in said ring of refractory elements on the joint between said ring and said refractory lining, said slots being adapted to be connected to a cold air supply conduit by way of a circular peripheral recess provided on said ring of refractory elements.

4. A device as claimed in claim 1, wherein said means for imparting a gyratory motion to the wind comprises a diaphragm mounted within said nozzle and having blading the blades of which are oblique relative to the axis of said nozzle.

5. A device as claimed in claim 4, wherein said diaphragm is mounted at the upstream end of said nozzle, that is, at the large diameter end of said nozzle.

6. A device as claimed in claim 4, wherein said diaphragm has extending therethrough a sighting tube for observing the inside of said tuyere.

7. A device as claimed in claim 4, wherein said diaphragm comprises an axial hub having a dome-shaped upstream end and a tapered downstream end in the form of an ogive.

8. A device as claimed in claim 4 wherein said nozzle has a nose portion at the downstream end thereof and said diaphragm is mounted in the region of said nose, a cooling water passage being provided in said nose.

9. A device as claimed in claim I, wherein said liquid fuel supply conduit is oblique relative to said nozzle and said injector has an outlet at the upstream end of said neck of said Venturi structure.

10. A device as claimed in claim 8, wherein said fuel supply conduit is bent at an angle which is highly inclined relative to the axis of said tuyere, and said injector is centered by said bladed diaphragm and has an outlet in the region of said neck of said Venturi structure.

11. A device as claimed in claim 1, comprising a flange on said tuyere for connecting said tuyere to said nozzle, said flange defining a socket having a part spherical inner face adapted to receive a nose of said nozzle.

12. A device as claimed in claim 1, wherein said nozzle has a nose cooled by a circulation of water.

13. A device as claimed in claim 1, wherein said nozzle has a nose having internal refractory material.

14. A device as claimed in claim 1, wherein said tuyere has a bulb shape which is divergent in the upstream direction.

15. A device as claimed in claim l4, wherein said tuyere is very short and connected to said nozzle by a connecting element cooled by the circulation of water and provided with a part spherical socket.

16. A device as claimed in claim 15, wherein said nozzle is part spherical and said nose of said nozzle is also part spherical and applied against said connecting element.

17. A device as claimed in claim 16, wherein said part spherical nozzle comprises a wind supply pipe which is tangent to the inside of said nozzle and inclined relative to the axis of said nose of said nozzle at an angle in the neighborhood of whereby to constitute means for rotating said blown wind and progressively deflect the fluid stream through the inner part spherical walls of said nozzle in accordance with a whirl whose diameter diminishes towards the axis of said tuyere in moving away from said wind supply pipe towards said neck of said Venturi structure.

18. A device as claimed in claim 17, wherein said pipe tangent to said nozzle comprises a part spherical flange.

Claims

1. A device for injecting liquid fuel into a shaft, and in particular into a blast furnace, said device comprising in combination a wind blowing nozzle and a tuyere in coaxial relation, refractory elements assembled in the form of a ring between the downstream end of said nozzle and the upstream end of the tuyere, relative to the direction in which said wind is blown, where they constitute a neck and a divergent part of a Venturi structure having upstream convergent part formed by said nozzle; a liquid fuel supply conduit carried by said nozzle and terminating in an injector located in the vicinity and on the axis of said neck; and means for imparting a gyratory motion to the wind blown through said nozzle.

8. A device as claimed in claim 4, wherein said nozzle has a nose portion at the downstream end thereof and said diaphragm is mounted in the region of said nose, a cooling water passage being provided in said nose.

9. A device as claimed in claim 1, wherein said liquid fuel supply conduit is oblique relative to said nozzle and said injector has an outlet at the upstream end of said neck of said Venturi structure.

15. A device as claimed in claim 14, wherein said tuyere is very short and connected to said nozzle by a connecting element cooled by the circulation of water and provided with a part spherical socket.

17. A device as claimed in claim 16, wherein said part spherical nozzle comprises a wind supply pipe which is tangent to the inside of said nozzle and inclined relative to the axis of said nose of said nozzle at an angle in the neighborhood of 90*, whereby to constitute means for rotating said blown wind and progressively deflect the fluid stream through the inner part spherical walls of said nozzle in accordance with a whirl whose diameter diminishes towards the axis of said tuyere in moving away from said wind supply pipe towards said neck of said Venturi structure.