US3456934A - Burner projecting into a rotary kiln - Google Patents

Description

July 22, 1969 H. RUCH 3,456,934

BURNER PROJECTING INTO A ROTARY KILN 7 Filed Feb. 23, 1 967 2 Sheets-Sheet 1 July 22, 1969 H. RUCH 3,456,934

BURNER PROJECTING INTO A ROTARY KILN Filed Feb. 23. 1967 2 Sheets-Sheet 2 United States Patent 3,456,934 BURNER PROJECTING INTO A ROTARY KILN Herbert Ruch, Mettmann, Germany, assignor to Dolomitwerke GmbH, Wulfrath, Germany Filed Feb. 23, 1967, Ser. No. 618,171

Claims priority, application Germany, Feb. 24, 1966,

D 49,430 Int. Cl. F27b 7/34 US. Cl. 263-33 7 Claims ABSTRACT OF THE DISCLOSURE A burner for burning refractories in a rotary kiln isoperated with oxygen or oxygen-enriched air which is fed through superposed outlet openings so as to direct a hot narrow fan-shaped flame against the charge while not affecting the walls of the rotary kiln not covered by the charge.

This invention relates to burners for rotary kilns employed in the production of burned or sintered refractories, where the burner projects from the discharge end of the kiln axially into the inner chamber and is fed with liquid, solid or gaseous fuel, and with oxygen or oxygenair mixtures.

Particularly for the production of highly sintered refractories such as sintered lime, dolomite or magnesite, it has been found of advantage to use in such kilns oxygen instead of air. The thus increased flame temperature produces higher sinter temperatures but, on the other hand, corrodes strongly the lining at the kiln head and in the sintering zone.

A method is known where, in order to protect the lining, the oxygen is injected in the longitudinal direction of the kiln between the flame and the material to be burned. Thereby, the increased flame temperature results essentially in an increased temperature of the charge to be sintered without affecting excessively the opposite portion of the lining. However, said method requires a high consumption of oxygen, and the free kiln lining adjacent the charge is still exposed to the increased flame temperature. In addition, at the end of the flame and at the beginning of the sintering zone, the oxygen is mixed with the flame so that, there, the energy of the flame is no longer concentrated on the charge. Therefore, it has already been proposed to introduce oxygen or an air-oxygen mixture through a lance from the discharge end of the kiln at an angle to the kiln axis in such a manner that the oyygen jet passes sideways into the space between flame and charge.

It is the primary object of this invention to provide a burner which avoids the recited drawbacks.

Other objects and advantages will become apparent from a consideration of the specification and claims.

I have found that in a burner operated with oxygen or oxygen-air mixtures the energy of the flame is transmitted essentially to the charge without alfecting the parts of the kiln lining not covered by the charge by arranging the oxygen outlets of the burner in an inclined position with respect to the charge.

This arrangement has the further advantage of utilizing the oxygen or oxygen-air mixture to impart optimum shape to the flame; the length and the temperature of the flame can be adapted to the requirements by adjusting the amount and velocity of the oxygen containing gases.

Further, the convective heat transfer from flame to charge is improved by the radical speed component.

It is of particular advantage to arrange the outlet openings for the oxygen containing gases one above the other; thereby, it is further advantageous to impart to Patented July 22, 1969 said superposed outlets different angles of inclination in such a way that said angles to the axis of the kiln increase from the upper outlets to the lower outlets.

The cross-sectional areas of the outlet openings preferably decrease from the upper to the lower openings. For equal pressure of the oxygen or oxygen containing gas, said arrangement provides for extension of the flame in the upper and upper middle area of the kiln chamber almost in direction of the kiln axis while in the lower middle and lower areas the flame is directed onto the charge. Thus, a fan-shaped flame is produced which extends in the direction of the kiln axis in the plane of the normal to the charge.

It is recommended to connect each outlet opening with a separate admission line for the oxygen containing gas. In this way, the form of the flame can be controlled very exactly by varying the gas pressure. In operation, the amounts and velocities of the oxygen-containing gases will be adjusted so as to produce .a fan shape of the flame which is most favorable for the desired burning effect.

For certain applications, it may be of advantage to provide outlet openings which impart torsional motion to the oxygen jet. In this way, the fan-shaped flame is widened in the direction onto the charge.

The burner of the invention can form a unit with the outlet nozzles for the oxygen; it is, of course, also possible to provide separate units for the feed of the fuel and that of the oxygen, the latter e.g. in form of a lance. Preferably, the cross-section of the fuel feed tube is in form of a horseshoe the inside of which receives the oxygen lance.

In the accompanying drawings, showing by Way of example, diagrammatically some embodiments of the invention.

FIG. 1 is a sectional view of the discharge end of a rotary kiln with a burner according to the invention;

FIG. 2 is a cross-section taken along line A-B of FIG. 1;

FIG. 3 is a front view of a two-part burner according to the invention;

FIG. 4 is a sectional view of an oxygen feed portion of a similar burner; and

FIG. 5 is a front view taken in direction C-D of FIG. 4.

Referring now first to FIG. 1 of the drawings, the numeral 2 designates the head of a rotary kiln 1 into which the burner 3 projects, which is provided at its lower part with inclined outlet openings 6 for oxygencontaining gas. This arrangement ensures that the upper part 4 of the flame receives only little oxygen while the lower part 5 receives the major portion of the oxygen. This results in a flame which forms a fan directed against the charge 7 and whose lower portion 5 is much hotter than the upper portion 4. This eflect can be further interisified by adjusting the feed of the oxygen-containing gas to the outlets so that the gas is the richer in oxygen the lower the gas outlet is.

FIG. 2 illustrates how the flame fan 5 can be expanded by providing turbulence producing inserts in the outlet openings.

A two-part burner according to the invention is shown in FIG. 3. There, the fuel admission encloses like a horse-shoe the oxygen feed line whereby the horse-shoe is opened towards the charge and where the outlet openings of the oxygen feed decrease in size downwardly. This is shown also in FIGS. 4 and 5, where the outlet openings 8, 9, 10 and 11 are from top to bottom, increasingly inclined towards the charge, While their crosssectional areas decrease in the same order.

In the following claims, the term oxygen" as used includes also air enriched in oxygen.

I claim:

1. A burner projecting into a rotary kiln for heating a charge to produce refractory material, comprising separate members for the fuel and oxygen feed, said fuel feed member being formed in the shape of an inverted U and surrounding the oxygen feed member, said oxygen feed member, including at least one outlet inclined towards said charge.

2. A burner as claimed in claim 1 wherein said feed member for the oxygen includes a plurality of outlets disposed one above the other.

3. A burner as claimed in claim 2 wherein said outlets are disposed at varying angles of inclination, said angles of inclination increasing from the upper to the lower outlets.

4. A burner as claimed in claim 2 wherein the crosssectional areas of said outlets decrease from the upper to the lower outlets.

5. A burner as claimed in claim 1 comprising means imparting turbulence to the oxygen leaving the oxygen outlets.

6. A burner as claimed in claim 2 including means for adjusting the amount and velocity of the oxygen feed so as to produce a fan-shaped flame extending in the direction of the kiln axis in a plane passing through said axis normal to the surface of the charge.

7. A burner as claimed in claim 6 wherein oxygen-enriched air is used and wherein the oxygen concentration in the outlets is made the higher the nearer the outlet is to the charge.

References Cited UNITED STATES PATENTS 797,506 8/1905 Eldred 26333 2,584,808 2/ 1952 Newhouse 263-33 X 2,654,592 10/1953 Harris 26333 3,074,707 1/ 1963 Humphries et al. 263--33 X JOHN J. CAMBY, Primary Examiner

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