US2375895A - Apparatus for sintering - Google Patents

Description

May 15, 1945. M. L. COVER APPARATUS FOR SINTERING Filed Dec. 11, 1941 nii aiiiimiillm GAS Patented May 15, 1945 UNITED STATES PATENT OFFICE APPARATUz z SmTERlN-G I Martin L. Cover, Allen Park, Mich, assignor to National Steel Corporation, a

Delaware corporation of 6 Claims.

This invention relates to an improved apparatus for sintering. 4

More specifically the invention relates to an improved apparatus for igniting a-moving bed of material to be sintered.

In conventional sintering machines a bed of material to be sintered is formed upon a moving conveyor. The material is ignited and draft-inducing apparatus causes the material to be sintered through the bed as the conveyor moves along. At a point where the sintering action is completed the sintered material is removed from the conveyor to storage.

Considerable difiiculty has been experienced in properl igniting the bed. A common system is to have the bed pass through a furnace heated up to over 2000 F. The temperature in the furnace does ignite the bed but not evenly so that some spots are sintered through while other sections are only partially sintered. In order to accomplish its purpose the bed must be exposed to the temperature in the furnace ior a reason able length of time with a resulting deleterious dehydration action of the material to be sintered. Another system commonly used for igniting the bed is a row of spaced open burners arranged across the bed with the flame directed toward the bed. This arrangement also has resulted in uneven ignition of the bed. In most cases the flame not allowed to contact the bed because a violent disturbance of the materials to be sintered would result. Where the flames do not contact the bed some spots are ignited and others are not. In all cases there are spaces between the flames which under some conditions are at a temperature high enough to ignite the bed and under other conditions are not. In general with this arrangement a line of flame hot enough to ignite the bed evenly across its entire width would be too violent in its mechanical distunbing action on the materials to be sintered. In the present invention .a system of igniting materials to be sintered has been developed in which an even soft flame is brought directly in contact with the bed. In order to reduce the violent action and obtain a flame as soft as necessary a plurality of closely spaced lines of flame are used. A burner arrangement has been developed which makes possible this system of ignition and control means are included to obtain the maximum degree of igniting action at all times. The system of the present invention ignites the materials to be sintered quickly without drying out the bed. As is well known, the amount of water in the bed is extremely critical where eificient sintering is required.

The present invention includes a burner made u of a series of burner heads so designed and arranged that a plurality of soft sheets of flame are directed at an angle to the bed and in contact with material to be sintered in such a manner that the fines in the bed are not blown around. When two sheets of flame are used they are at an angle to each other such that the bed is placed under igniting temperature for a suflicient time to obtain complete and even ignition, and at the same time secondary air is accessible to both flames.

An important object of the present invention is the provision of an improved apparatus for even ignition of a bed of materials to be sintered.

Another important object of the present invention is the provision of an improved apparatus for even ignition of .a bed of materials to be sintered without drying out the bed.

A further important object of the present in-- vention is the provision of an improved apparatus for even ignition of a bed of materials to be sintered without disturbing the bed.

A still further important object of the present invention is the provision of an improved burner for use with a sintering machine to obtaineven and quick ignition with a soft flame.

These and other objects and advantages will be apparent from the followin description and annexed drawing in which- Figure 1 is .a view partly elevation and partly in section taken across the bed,

Figure 2 is an enlarged view in elevation of .a burner head,

Figure 3 is an enlarged view in cross section taken on the line 3--3 of Figure 2, and

Figure 4 is a diagrammatic view of a sintering machine embodying the present invention,

Referring to Figures .1 and reference .numoral Iii indicates a bed of materials to be sintered carried by a conveyor H. A hopper l2 spreads the materials on the moving conveyor. To induce a draft for combustion a wind box 13 is positioned under conveyor H with a vacuum conduit 14 going to a fan not hown. Openings 1.5 in the conveyor allow air to be drawn downwardly into the bed and the Wind "box thereby supplies oxygen for the combustion of materials in the bed. Adjacent the hopper and above the bed are a pair of manifolds it and ll. In the specific embodiment herein described manifold 15 carries a fuel gas, although oil or any other form of fuel could be used equally well within the scope of the present invention. Manifold ll carries air or any other oxygencontaining gas. Conduits l8 lead from the air manifold to burner heads l9. A conduit 29 leads from the fuel manifold and into the air conduit adjacent the burner head. Conventional valves are shown in all the conduits for controlling the pressure of the fluids supplied to the burner head. Conduits l8 and .20 are broughttogether close to the, burner head in order to have present as small a volume of explosive mixture as possible.

Referring to Figures 2 and 3, burner head I9 presents a T or hammer shape by virtue of mixing chamber 2| which is connected to the end of conduit I8. In the specific embodiment shown a pair of slots 22 are formed in the lower section of mixing chamber 2| about 90 apart. These slots run the length of the mixing chamber and along the entire burner these slots line up in the adjacent burner heads to form two discontinuous lines. The burner heads are spaced so closely together that the discontinuities in each line are not present a short distance away from the burner in a flame emitted from the line of slots. This results in two sheets of flame each impinging on the bed at about a 45 angle.

. In operation with the bedin motion the valves in conduits I8 and 20 are adjusted so that an even continuous sheet of flame is produced by each lin of slots,,the length of the flame being such that it impinges on the. bed of materials to I be sintered. The slots are sufliciently wide and the pressures present are controlled so that the flame is soft, that is, the mixture of fuel and oxygen-containing gas emitted from the slots has a low velocity insuflicient to cause the products of combustion of the flame to disturb the finer particles in the bed. A slot with a gas pressure around 8 ounces per square inch gives a suitable flame when sintering the usual type of bed. It is to be understood however that any suitable relative dimensions and gas pressures can be used to obtain a soft flame. Complete ignition takes place in the present invention using a soft flame because of the angle of the flame to the bed and because of the plurality of spaced sheets of flame extending across the bed.

With the resulting even ignition of the bed its motion can be such that the material when dumped is just short of being sintered through. This prevents objectionable sticking of the sinter to the. conveyor. The bed in moving toward, through and beyond the burner is almost immediately subjected at its upper surface to ignition temperature on contact with the first flame,

starts to ignite in passing this flame and completes ignition in passing through the second flame thereupon to be no longer subject to any extraneous heat. This action prevents the usual drying out of the bed whichtakes place in the common systems as the bed is moved through a lengthy high temperature Zone.

I claim:

1. In a sintering machine of the type having a moving conveyor, a bed of material to be sintered carried by the conveyor and a burner system for igniting the bed, the burner system comprising a plurality of burner heads for receiving a combustible mixture of fuel and oxygen-containing gas, the burner heads being arranged in a line across the bed and spaced from the bed, a plurality of spaced slots in each burner head for emitting flame, the slots being arranged so as to form a plurality of sheets of flame at an angle to one another and in the direction of the bed, slots in adjacent heads falling in line so that the emitted sheets of flame from the burner form a plurality of substantially continuous and spaced lines at the bed.

2. In a sintering machine of the type having a moving conveyor, a bed of material to be sintered carried by the conveyor and a burner system for igniting the bed, the burner system comprising a plurality of burner heads for receiving a combustibl mixture of fuel and oxygen-containing gas, the burner heads being arranged in a line across the bed and spaced from the bed, a plurality of spaced slots in each burner head for emitting flame, the slots being arranged so as to form a plurality of sheets of flame at an angle to one another and in the direction of the bed, the slots being so dimensioned that the flame is soft and does not deleteriously disturb the material in the bed.

3. In a sintering machine of the type having a moving conveyor, a bed of material to be sintered carried by the conveyor and a burner system for igniting the bed, the burner system comprising fuel and oxygen-containing gas supply means, a burner connected to the supply means extending in a line across the bed and spaced therefrom throughout its length, and means associated with the burner for emitting a plurality of sheets of flame extending along the length of the burner at an angle to one another and in a direction such that the sheets contact the bed along a plurality of substantially continuous lines spaced from each other.

4. In a sintering machine of the type having a moving conveyor, a bed of material to be sintered carried by the conveyor and a burner system for igniting the bed, the burner system comprising fuel and oxygen-containing gas supply means, a plurality of burner heads arranged across the bed and spaced therefrom, means associated with each burner head for producing a sheet of flame extendin transversely of the bed and in contact therewith, the burner heads being so dimensioned and arranged that a continuous line of flame is formed at the bed extending across the same, a separate conduit connecting each burner head with the fuel supply means, a separate conduit connecting each burner head with the oxygencontaining gas supply means, and control means associated with the conduits for separate control of the flame produced by each burner head.

5. In a sintering machine of the type having a moving conveyor, a bed of material to be sintered carried by the conveyor and a burner system for igniting the bed, the burner system comprising fuel and oxygen-containing gas supply means, a plurality of burner heads arranged across the bed and spaced therefrom, means associated with the burner heads for producing sheets of flame extending transversely of the bed and in contact therewith, the burner heads beingso dimensioned and arranged that any point on the bed is contacted by at least two sheets of flame during movement of the same past the burner system, a

' separate conduit connecting each burner head with the fuel supply means, a separate conduit connecting each burner head with. the oxygencontaining gas supply means, and control means associated with the conduits for separate control of the flame produced by each burner head.

6. In a sintering machine of the type having a moving conveyor, a bed of material to be sintered carried by the conveyor and a burner system for igniting the bed, the burner system comprising fuel and oxygen-containing gas supply means, a burner connected to the supply means extending in a line across the bed and spaced therefrom throughout its length, and means associated with the burner for emitting a pair of sheets of flame extendirg along the length of the burner at an acute angle to the bed and in a direction such that the sheets contact the bed along a pair of substantially continuous lines spaced from each other.

MARTIN L. COVER.

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