US2069164A - Rotary kiln - Google Patents

Description

Jan. 26, 1937. M. voGEL-JoRGENsEN 2,059,164

ROTARY KILN Filed June 17, 1936 2 Sheets-Sheet l Jax-1.26, 1,937.v

M. voGEL-JoRGENsEN ROTARY KILN Filed June 17, 193e -2 sheets-sheet 2 Patented Jan. 26, 1937 Ypfiffig-:wr ori-ica ROTARY Mikael Vogel-Jorgensen,

Copenhagen, Denmark, A asslgnor to F. L. Smdth & Co., New York, N. Y., a, corporation of New Jersey L Application June 11, 193s, serial No. 85,689

, This invention relates to rotary kilns in which there is a drying zone for the preliminary drying of the materials to be calcined and sintered in the kiln. In such a drying zone'the'hot gases from the sintering zone give up some of their heat tothe material to be calcined and thus dry, and in some cases preheat, the material.- With a view to increasing the heat exchange between the gases' and. the material, chains are sometimes 1o provided in'the drying zone.v Again, with the same object in view, the area' of the internal surface o the kiln has been increased by the provision of xed heat-transmitting bodies or by dividing the kiln by longitudinal partitions into a Y number of parallel passages. Such means o promoting the heat exchange, are, however, somewhat expensive to install and it has been found that the raw materials, such as moist cement raw materials, tend to stick to parts xed in the kiln,

' and gradually to block up the whole cross-section of the kiln, to a greater or less extent. The present invention aims primarily at increasing the area of the heat-transmitting surfaces and at the same time at reducing the cost of installation and avoiding the diiliculties brought about byA sticking of the material. Y

In accordance with the invention one or more helical channels are formed by a helical partition or partitions in the drying zone and are charged -with loose bodies of heat resistant material. These bodies are prevented from passing from the channel or channels into the body of the kiln by one or more perforated walls or radial partitions which allow the hot kiln gases to pass through the channel or channels in counter-current to the material. The material itself is distributed over the bodies in the form oi slurry and thus becomes dried and preheated during its passage through the channelor channels. In this way the area of the heat transmitting surfaces between the raw material and the gases is made very large and the helical construction of the channel or channels leads to the accumulation of the heat transmitting bodies at the perforated end wall or walls so that the kiln gases cannot find a clear path of escape but are forced through the interstices of the charge of heat transmitting bodies over the whole cross-section of the channel and thus promote theV transmis- 50 sion of heat' to the bodies and to the material intermingled with them. As the kiln rotates the bodies will move constantly relatively to one another and thus the material on them is dislodged from the bodies and the partitions and conveyed further down the kiln, and the sticking o i the In Great Britain June 26, 1935 4 :(Cl. 263-.-33)

material in the channels is avoided. When the material has been suiliciently dried it must not be crushed into fine particles lest it be carried as dust out of the kiln by the gases and precautions may have to be taken to prevent it being crushed 5 too fine as the result of one body grinding on another. For this purpose the helical channel may be divided into several sections by means of perforated walls'and each section may )contain a charge of bodies, the bodies nearer the mouth 10 of the kiln having less relative movement than those nearer the upper end of the kiln. Thus when the'material is dry and easily broken vup-into powder the loose bodies have comparatively small relative movement and dol not tend to grind the 15 material very much. On the other hand, at the points where the material resembles paste, a smaller number of bodies may be used and these may be of larger size with the result that they have larger and heavier movement than the other 20 bodies and thus prevent clogging at the points where it would otherwise be most likely to occur.

In order to make the channel or channels sufficiently large in cross-section, so that the resistance to the passage of the kiln gases is not too 25 great, the drying zone may be made larger in diameter than the body of the kiln.

In order that the invention may be clearly understood and readily carried into effect it will be described with reference to the accompanying 30 drawings in which, by way of example, several embodiments are illustrated and in which:

Figure 1 is a view partly in elevation and partly in longitudinal section of a kiln, the heating zone of which is formed with a double helical 35 channel without radial partitions.

Figure 2 is a view in longitudinal section, on a larger scale, of the heating zone of a kiln formedV with a single helical partition and a radial partition, the partitions in this instance rotating with 40 the kiln.

Figure 3 is a view similar to Figure 2, but showing the partitions as rotated independently of the kiln.

Figures 4, 5 and 6 are views in section .on the 45 plane indicated by the line 4-4 oi. Figure 2, Figures 5 and 6 representing the conditions which obtain in the kiln when the kiln has turned and respectively from the position shown in Figures 2 and 5. 50

Figure '7 is a view-similar to Figure 2, but showing a plurality of radial partitions.'

Figure 8 isa. view in section on the plane indicated by the line 8-8 offFlgure 7.

As shown in Figure 1, slurry is fed to thekiln 55 -this charge moves as the kiln rotates.

through a pipe I and passes into a widened drying zone 2. This contains two helical partitions 4b, which form two helical channels. The iigure does not illustrate the perforated the charge of loose bodies, because it is intended simply to show the position of the drying zone in the kiln and the tions to the drying zone.

In Figure 2, there is shown a widened drying zone 3 which contains two turns of a single heliranged radially and having slotted openings dependently of and relatively to the kiln shell by means of a driving connection applied to the shaft 5, which is extended out through the ,feed

the helical channel Without varying the speed of the kiln. Figures 4, 5 and 6 show the charge of loose bodies 8 and illustrate the way in which In the position shown in Figure 4' the grid 1 is nearly vertical below the shaft 5 so that the hot kiln gases are forced to pass through the charge of bodies 8. As the kiln rotates the slurryl fed to the kiln is\conveyed to the charge of bodies 8 by the helical partition 4 and is distributed over these bodies. As it dries on the bodies and n thepartitions it is gradually rubbed off owing to movement of the through the 'grid 1. As the kiln moves from the position shown in Figure 4 to that shown in Figure some of the bodies roll beyondI the shaft 5 and drop intothe helical channel at the lowermost part of the kiln, but nevertheless many of relation of the helical parti- A bodies and passes a,oc9,1c4

vthe bodies remain resting against the grid 1.

When the grid arrives at the position shown in 6 all the bodies have moved away from the grid and completely nil the helical channel so that the gases are compelled to pass through the interstices of the`charge of loose bodies and are thereby brought into close contact with the bodies and eiectively transmit heat thereto and to' gases are forced to pass through two masses of the loose bodies. ber may be smaller and may substantially fill the whole of this chamber.

I claim as my invention: 1. A rotary kiln having a drying zone for maal to be MIKAEL VOGELJORGENSEN. I

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