US2003180A - Method for carbureting heavy liquid fuels - Google Patents

Description

May 28, 1935. G, LUCiCH ZSS METHOD FOR` CARBURETING HEAVY LlQUID FUELS Filed Aug. 4, 1934 FIC-3.3

Patented May 28, 1935 UNITED STATES METHOD FOR CABBUBETING HEAVY FUELS LIQUID Giovanni Luclclx, Trieste, Italy, assigner to iirm Societ Anonima Carbm'atori Olii Pesanti (S.- A. M. C. 0.), Trieste, Italy, a corporation of A Italy Application Ain-u 4, 1934, sei-m1 No'. 719,018 In Italy November 16, 1933 .7 claims. (ci. 15s-117.5)

This invention relates to a method for carbureting liquid fuel, for example for the heating of boilers'with naphtha and the like, in accordance with which the fuel is rst sprayed pref- 5 erably by means of compressed air, then supplied to a mechanically acting atomizer, and thence conducted to the point at which it is to be burned, and consists essentially in the fact that the chamber in which the fuel is mechanically atomized and simultaneously commixed with air is cooled. The hitherto known and actually used heavy oil carbureting devices have not been capable of mixing heayy oil or naphtha with air so intimately that perfectly smokeless combustion is ensured. The main reason for this fact has been that the heavy oil is fed to the mechanical atomizing device, the purpose of which is primarily to mix the components of the heavy oil with air, partly in a liquid, but also partly in an already vaporized state. This is the case since the heavy oil must necessarily be heated before introduction into the carbureting device in order that it may acquire suiliciently thin liquid consistency as to permit of its atomization by means of compressed air. This preliminary heating,

however, causes a large part of the components of the heavy oil, namely the more readily vaporizing components, to become converted into a vapcrous or gaseous state. Asin fractional distillation, these volatilized components are the rst to pass into the mechanical atomizer, and traverse the same more rapidly than the liquid particles of the heavier components. These volatilized components are thus broug'ht into less intimate contact with the simultaneously eddied air than the liquid particles of the heavier components, by impact against the moving parts and the walls of they carbureting device, and consequently pass into the ilame for the greater part still in the form of vapor inadequately commixed with air.

The present invention aims at maintaining all the components of the heavy oil when heated according to the known practices, as stated, in cluding the readily vaporized components, in a liquid state in the mechanical atomizer, since, as exhaustive tests have proved, it is only under this condition that such intensive commixture with air takes place that absolutely smokeless 5o combustion results. This invention provides the only possibility yet known of carbureting all the ,components of heavy oil uniformly and completely, and of enveloping each of the minutest particles of the atomized liquid with The essential `feature of the invention is that the fuel-air mixture while in the mechanical atomizing portion of the carbureting device is cooled, and that to such an extent that even the most readily vaporizing components of the oil are condensed back into liquid in the form of 5 minute particles.

In this connection a particularly favorable eii'ect is achieved by virtue of the further fact that the liquid particles produced in the described manner, that is to say by condensation, 10 are smaller than thoseproduced by mechanical atomization, so that a hitherto unequalled degree of homogenizing and atomization, with the simultaneous enveloping with air of each liquid particle produced by condensation, is achieved. 15 'Ihe cooling can be effected by the action of cold applied from the outside, but. preferably by utilization oi the phenomenon of physics that vapor traversing a tube is condensed by the expansion= occurring at a point at which the cross-sectional area of the tube enlarged. For the utilization of this principle in the present instance it is important, in determining the dimensions ofthe carbureting device, that the cross-sectional enlargement be of such magnitude that even the most readilyvolatile components of the heavy oil are condensed to liquid ,particles in the form of extremely ilne mist.

The invention can also be employed to equal advantage not only for heavy oils proper but also for liquid fuels of lower specific gravity, and more particularly for gasoline and mixtures thereof with benzol, spirits, naphtha, and the like, and permits of the attainment of a hitherto unequalled degree of perfection in the commixture of fuel and air.

A device for the carrying out of the"method according to the present invention, and more particularly..for the purpose of burning naphtha and heavy oils consists, in view of the abovedescribed principles, oi a. part in which a mixture of sprayed fuel and air is produced, and o1' a further part, comprising the mechanical atomizer, in which the drop-shaped particles of heavy oil are very nely broken up and atomized, and .in which the mixture is homogenized by means oi ian wheels and filters.

A constructional example of a heavy oil carbureting device in accordance with the invention is shown in the accompanying drawing, in which:

Fig. 1 shows a carbureting device for heavy oil combustion, in longitudinal section.

Fig. 2 shows the same in elevation.

Fig. 3 shows a lter,

' tion of a primary mixture of air and sprayed heavy oil consists for example of a tube 4 into the wall of which there are tted the injecting nozzles 8 and 9 for the heavy oil, and into which compressed air enters in the direction of the arrow 5. To obtain the expansion of the mixturel required in accordance with the invention, the inside of the tube 4 is conically'enlarged from the nozzle orifices 4I onwards, in the direction of flow. For the purpose of the convenient regulation of the quantity of heavy oil injected into the tube 4, with a' view to increasing or reducing the flame, the orices 4I of the nozzles 8 and 9 are preferably of different cross-sectional areas. 'I'he regulation is effected in a known manner, for example by means of a needle 43 operated by rotation of the knob 44. I

The cross-sectional area of the inlet in the tube 4, for the admission of compressed air, can be set for a particular size of flame or for a particular heating eifect, by means of interchangeable bushings 40 the aperture of which is gradually enlarged to each side.

The mixture ,of fuel and air produced by the sweeping of the air intake with considerable speed past the jets of sprayed oil issuing from the orifices of the nozzles then passes into the mechanical atomizing device in which the fuel is reduced to an extremely fine mist, and in which the mixture is homogenized to the greatest possible extent. This device may be of any suitable or known construction and consists for example of the preferably two-part casing I2, I3 in which the fan wheels 24, 25 and the filters 26, 28 are arranged upon the shaft 22 disposed in the direction of ilow.' While the fan wheels are rotatable upon the xed shaft, by means of the roller bearings 23, the filters 26, 29 are tted in cylindrical bushes 20, 28, the outside diameter of which corresponds to the inside diameter of the casing I2, I3.

The shaft 22 is mounted at one end in the disc I8 which is pressed against the tapered part 45 of the casing and held in position by thepressure exerted upon the bushes 2B, 20 on the tightening up together of the two halves I2 andI I3 of the casing by means of the screws 30.

For the purpose of obtaining the expansion and consequent cooling of the mixture according to the invention, the portion I2 of the casing of the atomizer, at the end at which the mixture enters, is tapered, so that its cross-sectional area is greatly enlarged for a short portion of the path of flow.4

The disc I8 and the disc I1, which is immediately adjacent thereto but rotatable in the casing, are each provided, as shownl in Figs. 5 and 6, with radial slots 46,' and these two discs constitute jointly a device for the regulation of the quantity of the fuel mixture passing to the atomizer. By means of the screw pin I8 passing through a slot in the casing and provided with a head I5, the disc I'l can be rotated to such an extent thatthe slots in the two discs can be be caused to register completely or partly, that is to say that the slots in the one disc can be more or less completely covered by the intervening solid portions of the other disc.

.The fuel mixture entering the casing I2, I3 under pressure causes the fan wheels 24, 25 to rotate at very high speed, and preferably in op,- posite directions in consequence of suitable adjustment and setting of the blades. This arrangement has the effect of completely breaking up the liquid particles of the incoming mixture into a state of the finest mist, and. at the same time of thoroughly intermixing and homogenizing the atomized fuel with air. This effect is still further increased by the provision of the lters 26, 29 which are arranged in alternating sequence with the fan wheels, and which divide up the mixture passing therethrough into a large number of iine threads. These filters can either consist in a known manner of wire gauze or can be made honeycomb-fashion of a number of closely juxtaposed channels for the passage of the mixture.

The described manner of mountingV the shaft 22, the throttling discs I1, I8, the fan wheels 24, 25, and the filters 26, 29 permits of the convenient removal, as a single unit, of the whole of the internal mechanism of the atomizing device proper, after the slackening oi of the flange connection between the two halves of the caslng I2, I3.

In order to enable the cooling of the mixture byexpansion on` entering the atomizer casing to be intensified in case of need, or of enabling this cooling to be effected, if desired, without expension of the mixture, the casing I2, I3 is jacketed, so that a cooling medium can be caused to circulate in the space between the double walls of this'jacket.

Conversely, however, it can also become necessary, in cases of excessive cooling by expansion, which may even go below the freezing point of water so that the casing becomes coated with a layer of ice formed of the moisture condensed from the atmosphere, to pass a heated medium through the jacketing of the casing, with a view to maintaining the most favorable temperature for the atomizer.

Instead of arranging for both fan wheels to rotate, it is also possible to arrange for the wheel traversed last to be stationary. In this case this latter wheel is preferably constructed in the manner indicated in Fig. 'l with blades of maximum radial length, for the purpose of reducing the throttling resistance to a minimum.

For the attachment of the atomizer to Ihe wall I ofthe combustion chamber there is preferably employed theA tubular member 33 which can .be double walled if necessary to permit of artificial cooling and to prevent excessive heating of the carbureting device casing by the heat conducted from the wall of the combustion chamber.

Exhaustive tests have shown that it is possible to obtain -absolutely smokeless combustion of the fuel mixture with the aid of the method and carbureting device according to the present invention. The combustion is accordingly also effected with a degree of thermal efficiency which very considerably surpasses that of known heavy oil burners, since all the components of the liquid fuel are consumed leaving no residue. In the case of furnace heating both the boiler and the fire-box thus remain free, from solid, coked residue of combustion, but neither do fuel particles leave the flame in the liquid and non-combusted state, as is not infrequently the case with known burning devices, so that the combustion chamber is not fouled in any sense.

The increase in thermal efficiency obtainable by the use of the method and carbureting device according to the present invention over that obtainable with known types ofheavy oil burners is very considerable. and is of particular advantage in connection with the heating of marine engine boilers.

What I claim is:

l. 'Ihe method of carbureting liquid fuel which consists in partially pre-vaporizing and spraying the fuel and mixing air therewith to form a primary mixture in which part of the fuel is in a vaporous state, mechanically breaking up the non-vaporized particles of fuel in the mixture, and at the same time cooling the vaporized portion of the fuel to condense the same and form minute liquid particles.

2. The method of carbureting liquid fuel which 'consists of partially pre-vaporizing and spraying the fuel andV mixing airA therewith to` form a primary mixture in which part of the fuel is in a vaporous state, mechanically breaking up the non-vaporized particles in the mixture, and at the same time cooling the mixture to such a temperature that the most readily volatile constituents of the fuel are condensed and converted into minute liquid particles.

3. The method of carbureting liquid fuel which consists of partially pre-vaporizing and spraying the fuel and mixing air therewith to form a primary mixture in which part of the fuel is in a vaporous state, mechanically breaking up the non-vaporized particles in the mixture while expanding the mixture to cool the same and reduce its temperature to a point at which the vaporous contents will be condensed and form minute liquid particles.

4. The method of carbureting liquid fuel which consists of partially pre-vaporizing and spraying the fuel and mixing air therewith to form a primary mixture in which part of the fuel is in a vaporous state, mechanically breaking up the non-vaporized particles in the mixture while expanding the mixture to reduce its temperature and controlling its reduced temperature whereby vaporous contents of the mixture will be condensed and formed into minute liquid particles which are then intermingled with the broken up non-vaporized particles.

5. The method of carbureting liquid fuel consisting of mixing air with sprayed partially prevaporized liquid fuel to form a primarymixture, cooling the mixture to condense vaporous portions thereof into minute particles, and breaking up larger particles of liquid fuel and mixing therewith the said minute particles and air.

6. The method of carbureting liquid fuel consisting of mixing air with sprayed partially prevaporized liquid fuel to form a -mixture, changing the temperature of the mixture to a point at which substantially all of the Yaporous portions thereof will be formed into minute liquid particles, and mechanically breakingA up larger liquid particles and mixing the minute particles with the broken up particles and the air.

7. The method of carbureting liquid fuel consisting of mixing air with sprayed'partially pre vaporized liquid fuel to form a primary mixture. changingv the mixture to reduce its temperature' tc a point at which vaporous contents thereof will be condensed and converted into minute liquid particles, and mechanically breaking up larger liquid particles and mixing therewith the minute particles and the air.

GIOVANNI LUCICH.

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