US2112887A - Method of igniting a sintering charge - Google Patents

Description

April 5, 1938. J. E. GREENAWALT 2,112,887

METHOD OF IGNITING A SINTERING CHARGE Filed March 1, 1957 2 Sheets-Sheet l April 5, 1938. J. E. GREENAWALT METHOD OF IGNITING A SINTERING CHARGE Filed March 1, 1957 2 Sheets-Sheet 2 K M Nm f n wm 4 MN MN Patented Apr. 5, 1938 UNiTEo STATES PATENT OFFICE John E. Gi-eenawalt, New York, N. Y.

Application March 1, 1937, Serial No. 128,362

2 Claims.

My invention has relation to improvements in methods of igniting a charge of material to be sintered and it consists in the novel features more fully set forth in the specification and pointed out in the drawings.

It is a matter of common knowledge among metallurgists that in the sintering of fine ores, flue dust, or similar material, it is of the utmost importance in producing good 'sinter that the ignition of the charge must be quick, thorough and applied practically simultaneously over the entire surface of the charge. Many types of igniters and various methods of igniting have been resorted to to obtain these results but, as far as I am aware, until the application of my improved method of igniting a sinterable charge herein described none of such methods is completely satisfactory. All of the older methods of igniting a charge occasionally produce desired results as a fortuitous circumstance, and not as a rule. Under the method of ignition herein described the rule is reversed, and instead of occasionally obtaining complete and effective ignition, it is only occasionally that the method fails to produce such results.

These advantages, as well as others inherent in the invention, will be better apparent from a detailed description of the same in connection with the accompanying drawings, in which:

Figure 1 is a top plan and sectioned on the line I-I of Fig. 2 showing the igniting hood used in practicing my improved method of igniting a charge of material to be sintered; Fig. 2 is a vertical longitudinal section taken on a plane indicated by the line 2--2 in Fig. 1 with the upper portion of the sintering pan and the top surface of the material therein shown dotted; and Fig. 3 vis a vertical cross section taken on a plane indicated by the line 3-3 of Fig. 1 with the top of the sintering pan and the upper surface of the material indicated by dotted lines.

The method will be best understood by describing the igniting hood and burners carried thereby with reference to the drawings, in which: I, I represent end members and 2, 2 side members, all of which are suitably secured together to constitute the hood frame, across the top of which, from one side member 2 to the other, are disposed a series of I- beams 3, 3, etc. There are a series of supporting members 4, 4 arranged beneath and carried by the I- beams 3, 3 for the purpose of supporting rectangularly shaped roof plates 5, 5, etc.

The two rows of roof plates 5', adjacent the end members I, I of the frame are supported by (ci. ess-2i) the lining plates 6, 6 on the inside of the frame members I, I and the adjacent supporting members 4, 4. There are two (in the present instance) burner housings 1, 'I arranged in the igniting hood so as to be an equal distance from 5 the sides and ends of the hood fr-ame and from the center I-beam 3 thereof, said burner housings being carried by adjacent I- beams 3, 3 and in turn supporting a motor M, the shaft S of which extends downwardly into the housing 1 lo and has a fuel distributing head 8 fixed on its lower extremity. A tubular c-asing 9 is arranged within the housing 'I and encases shaft S, said casing being supported from the top l of the housing 1. Carried by the casing 9 is a cage le Il) which in turn supports a gas receiving member II, the lower end I2 of which extends into the distributing head 8 so that the gas outlet I3 of the member II will be in communication with the peripheral orifices I4 for the discharge of 2@ the gas and air mixture. A plurality of radially arranged fan blades I5 project upwardly kfrom the periphery of the distributing head '8 and serve as impellers for the fuel mixture as it leaves the. orifices I4. A pipe I6 leads into the gas g5 receiving member II from a suitable source of gas supply not shown.

The specic details of construction of the burner are fundamentally the same as those of the burner of my Patent No. 2,072,587 dated 30 March 2, 1937, and are ndt claimed herein so do not require detailed description.

A sealing frame Il' is disposed around the lower edges of the end members I, I and side memn bers 2, 2 and is supported for vertical movement 35 by chains I8 and I3 operating over pulleys 2li and ZI and a drum 22. The sealing frame is guided during its movement by guide rods 23 and 26 operating through perforated bosses 25 and 26. The chains I8 and I9, pulleys 2li, ZI and drum 4o 22 are not shown in construction but are merely indicated by dot and dash lines` as the construction and arrangement of the sealing means is not an indispensible part of the present invention.

The parts above described collectively comprise an igniting' hood H which is freely movable over a sintering pan P (indicated by dotted. lines) in which is disposed the material m that is to be sintered. As is well known in the art, the material m is in the form of comminuted particles which are moistened en masse prior to being charged into the pan P. The purpose of the moistenin'g is to enable the material to be arranged in a compact layer of substantially uniform density so that when suction is applied to the l-ayer it will remain intact and resist the formation of blow holes. After having arranged the charge of material m in the pan P, the igniting hood H is moved over the pan (as shown in Figs. 1 and 2) and the sealing frame I1 lowered incontact with the top flange f of the pan P. The motor M is now started so as to rapidly rotate the distributing head 8, after which gas is admitted into the gas receiving member Il.'

The rapid rotation of the distributingl head 8 causes air to be sucked into the distributing head through the opentop of burner housing 1 to mix with the gas, which mixture is then expelled from the orifices Il which serve as peripheral nozzles. 'I'he fan blades I5 create a movement of air from the periphery of the distributing head radially outwardly from said head and after the combustible mixture has been ignited, (by applying a torchto either of the openings 21) the rapid rotation of the head 8 causes an intense swirling of the flame throughout an extensive area around the distributing head. While the main volume of air necessary to support the combustion of the gas is admitted through the distributing head, a complementary quantity of air is admitted to the hood H in the immediate vicinity of the distributing head through a plurality of perforations 2l, 28 in the roof plates 5, 5".

In the application of the invention illustrated and described herein I show two burners in the igniting hood H on account of the great size of the sintering pan P. Obviously, if the sintering pan P is smaller, one centrally located burner is sufficient to supply the entire igniting hood with an intensely hot flame.

In the application of the invention to a sintering charge there is obtained a swirling action of the flame from a central burner to the outer margins of the charge so that every square inch of the entire surface is covered with a flame of uniform intensity.

This insures absolute uniform ignition wherein there are no spots in the surface to be ignited any hotter than the balance of said surface. The flame is swirled around within the hood from the center thereof outwardly so that every square inch of the charge will have applied to it sufficient heat to be completely and thoroughly ignited. The ignition is almost instantaneous at al1 points on the surface of the charge and proceeds uniformly throughout the charge so as to produce a uniformly sintered product of homogeneous density. The excellence of the result is partly explained by the formation of a sintered crust on the top of the charge immediately ignition is effected which serves to distribute the flow of air uniformly through the charge, eliminating the tendency for the suction to pull material downwardly through the grate in spots with the formation of blow holes through which the air can short-circuit to the detriment of the remainder of the charge.

Having described my invention, I claim:

1. In the sintering of a charge of material, the method of igniting said material which comprises the application of a mass of flame and combustible gases above the surface of said charge, confining said mass within the margins of the charge undergoing ignition, and causing the flame and combustible gases to move outwardly from a central zone with a swirling motion and suflicient velocity to maintain practically uniform intensity of combustion over the entire surface of the charge.

tion to pass downwardly through the charge over f the entire surface thereof, applying a swirling JOHN E. GREENAWALT.

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