US1552438A - Burner and method of burning fuel - Google Patents

Description

- Se a, 1925.

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Patented Sept. 8, 1925.

UNITED STATES VERNON G. LEACH, OF CHICAGO, ILLINOIS.

BURNEE AND METHOD OF BURNING FUEL,

Application filed March 21, 1924, Serial No. 7oo,78e.

To all 'whom it may conccrm- Be it known that I, VERNON G. LEACH, a citizen of the United States, and a resident of the city of Chicago, in the county of Cook and State of Il1inois,'have invented certain new and useful Improvements, in .a Burner and Method of Burning Fuel; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had-to the accompanying drawings, and to the numerals of reference marked thereon, which form a part of this specification.

This invention' relates to a burner and method of burning fuel more particularly designed for pulverized fuel.

In the large majority of burners designed for the use of finely divided fuel, the fuel is introduced into the furnace suspended in a current of air, both air and fuel b Upon being introduced into the furnace, the fuel gives off its volatile content almost instantly, and this volatile content readily burns. The small particles' of devolatilized fuel, however, soon surround themselves with an atmosphere of carbon monoxide or carbon dioXide which has to( be scrubbed ofl' before further combustion can proceed. This scrubbing action is best brought about by the Creation of a relative velocity between the fuel particle and the surrounding atmosphere of gases. Either the fuel particles should travel faster than the gases, or the gases should travel faster than the fuel particles. If there is such relative 'movement of the particles and gas, the film of partially-consumed gases which surrounds each fuel particle will be constantly scrubbed off and combustion will be completed in a I short length offiame travel.

Finely divided fuel, being highly explosive when thoroughly mixed and Suspended in the proper amount of air, should be introduced into the furnace at a muzzle velocity that creates an ample margin of safety ,between the velocity of the entering fuel and the velocity of rate of flame propagation, in order that the fire shall not creep back into the 'feeder line and create an explosion. It is exceedingly difficult to give this desired muzzle velocity without drving the fuel a great distance through the fur-.

nace and creating a very long flame which', of course, wll necesstate very large furnaces.

The principal object of the present inven- REISSUED tion it to provide means and method for obtaining short fiame combustion and this is attained first by a high muzzle velocity. and second by instantly spreading the entering air and fuel out over a wide area so that their forward velocity is very greatly reduced, thus securing all the benefits of a low velocity burner with the safety margin of the high velocity burner.

Now I have found that these advantageous results can be obtained by the use of a burner having two passages therein adapted to project streams of fuel and air obliquely inwards against each other to pro- "duce a fan-shaped fiame in a plane perpendicular to the plane in which such passages lie.

The scrubbingaction, above referred to, is brought about by the rapid slowing up of the air introduced through the burner by the mutual impingement of the jets which result in the spreading of the combustible mixture in a fan-shaped spray'. The fuel particles have stored in them a certain amount of kinetic energy which causes thenr to shoot forward at a higher velocity than the air or gases in which they have been supported.

Other and further important objects of this invention will be apparent from the disclosures in the specificati'on and drawings.

The invention (in a preferred form) is illustrated in the drawings and hereinafter more fully described.

On the drawings: v

Figure 1 is a side elevation of a burner constructed in accordance With the present invention.

Figur-e 2 is a plan'view of the same.

`Figure 3 is an end View of the same Figure 4: is a section on the line 4,--4 of Figura 1.

' Figure 5 is a section on the line 5--5 of Figure 2.

Figure water tube type the improved burners.

Figure 7 -is a secton-'on the line 7- qf Figure 4.' v

Figura 8 is a vertical section through another form of 'water tube'.`boiler showing three alternative positions of the burner.

Figure 9 is a .vertical section through a Stirlng boiler' fitted with the mproved burners.

6 is a vertical section through a boiler fitted witli one of&

Figure 10 is a section on theline 10--10 of Figure 7.

F igure 11 is a section through a reverbatory furnace fired by a burner constructed in accordance with the present invention.

As shown on the drawings:

The burner is constructed with two passages therein adapted to project streams of air carrying powdered fuel against each other to produce a fan-shaped flame in a plane perpendicular to the plane in which said passages lie. Various forms of construction may beemployed. In the particular form illustrated by way of example the burner 10 is formed 'from a metal tube flattened at the end and depressed inwardly at its center portions as at 11, and provided with an exit orifice 12. By flattening the tube and curving the ends inwardly two passages are formed on either side of the flattened portions 11 adapted to project streans of air and powdered fuel obliquely against each other. These impinging streans create a fan-shaped flame perpenlicular to the plane in which suclrpassages Je. i

Various installations of burners are shown in F igures 6 to 11 inclusive. In Figures G and 7 a burner 14: is shown in connection with a horizontally-baffled water-tube boiler comprising steam drum 15, header 16, downcomer 17, tubes 18, brickwork setting 19 and battles 20 and 21.

The burner 14 is inserted through -an aper- -ture in the front wall of the boiler setting so as to direct a laterally extended sheet of flame beneath the boiler.

In Figure 8' is shown three alternative applications of a burner 22 in connection with a vertically baflled water-tube boiler.

An arrangement in which one, two or three burners maybe employed simultaneously is shown in Figures 9 and 10 where burners 25, 26 and 27 are employed for heating a Stirling or vertical water-tube type boiler. One of these burners 25 is arranged in the bottom of the combustion chamber While the other two, 26 and 27, are. located' at opposite points in the side walls of the combustion Chamber. i In Figure 11 a metal furnace 30 is shown fitted with a burner 31 of the construction above described. Air is fed to the burner by means of a fan 32 and simultaneously' powdered fuel is supplied to the burner from a bin 33 by the feeder 34.

While a portion or all of the air required for combustion is introduced with the fuel from a suitable blower, additional air may,

if desired, be introduced into the combustion chamber as for example through apertures 28 as shown in Figures 6 to 10.

It is desirable that the fuel shall be intinatelyand uniformly mixed and distributed throughout the current of air issuing from the burner. In the conveying and distribution of finely divided fuel Suspended in air, the tendency is for the particles of fuel to separate out and travel along instrata or streaks, creating an uneven or spotted combustion condition in the furnace. The construction of this burner is' such that the finely divided fuel is very intinately remixed or blended with the air in which it is Suspended at the very point of introduction into the furnace. This nixing or blendingaction, coupled with the slow flame velocity and acconpanied by the maximum difference in velocities between the fuel particles and their surrounding atmosphere causes the flame to be unusually short and the combustion efficieney to be very high. To these advantages may be added the margin of safety created by a high muzzle velocity which is ordinarily much higher than the rate of .flame propagation.

I ani aware that many changes may be made and numerous detals of Construction i may be Varied through a wide range without departing from the principles of this invention, and I-there'fore do not purpose lmiting the patent granted otherwise than necessitated by the prior art.

I claim as my invention:

1.An apparatus for burning powdered fuel comprising a source of powdered-fuel, a source of air under sufiicient pressure to project the powdered fuel mixed therewith through a burner at a speed greater than the speed of flame propagation through the mixture, said burner having two passages therein adapted to project streans of air carrying powdered fuel obliquely inwards against each other to produce a fan-shaped flame in a plane perpendicular to the plane in which said passages lie.

2. A method of burning powdered fuel conprising projecting two streams of air carrying powdered fuel against each other at a speed greater than the speed of flame propagation whereby ignition does not occur until the velocity of the streans is reduced by the mutual impingement.

In' testimony whereof I have hereunto

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