Heating – Tumbler-type rotary - drum furnace – Having brick-type lining
Reexamination Certificate
2000-06-13
2001-10-30
Lu, Jiping (Department: 3749)
Heating
Tumbler-type rotary - drum furnace
Having brick-type lining
Reexamination Certificate
active
06309211
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to rotary kilns, and more particularly to an air conveying system for the introduction of port air into the bed of material being processed in a rotary kiln.
In currently utilized ported rotary kilns, the rotary kiln includes a series of openings extending through the refractory lining and outer shell to allow air to enter into the kiln to enhance the process occurring within the kiln. Typically, the series of openings each include a metal grid that is flush mounted with the inner surface of the kiln refractory lining, as is shown in U.S. Pat. No. 5,248,330. Although this type of grid is effective to prevent large particles of material from entering into the duct work introducing the air, the grid is directly exposed to both the high temperature and the hot tumbling material within the open enclosure of the rotating kiln. The high temperature and the physical contact with the tumbling material causes wear to the grid, which must eventually be replaced.
Additionally, the grid size of the flush mounted grid of the prior art allows small particles of material to enter into the duct work. These small particles can eventually plug the duct work causing a reduction or total loss of port air flow. If for any reason there is a loss of port air, the metal grid will quickly melt due to contact with the hot tumbling material within the kiln.
SUMMARY OF THE INVENTION
The rotary kiln of the present invention includes a novel air conveying system for delivering a supply of port air beneath the material bed of feed stock passing through the interior of the kiln. This new air delivery system eliminates the prior art method of using flush mounted grids with ported air and the attendant problems associated with such grids.
The air conveying system includes an air inlet port disposed in the shell of the kiln, a main air conveying channel which communicates with the air inlet port, and at least one air vent channel communicating with the main air conveying channel and the interior chamber of the kiln. The main air conveying channel is formed integrally in the refractory material which lines the inner surface of the kiln shell and extends longitudinally and parallel to the rotary axis of the kiln. The air vent channel extends through the refractory material substantially radially with respect to the rotary axis of the kiln.
The refractory material includes a plurality of new specially shaped bricks, referred to herein as refractory channel port bricks (RCP bricks), disposed longitudinally and circumferentially adjacent one another in a staggered arrangement, and the main air conveying channel and a plurality of air vent channels are formed integrally therein. More specifically, a main opening is forming through each brick and extends from the front face to the rear face thereof. When the bricks are assembled in place, the main air openings in adjacent bricks are aligned and form the main air conveying channel. Preferably, the main air opening is formed in the bottom face of each brick and is substantially U-shaped in cross section so that the main air conveying channel extends along the inner surface of the kiln shell.
An air vent channel is also formed in each brick and extends from the main air conveying channel to its top face. Preferably, each air vent channel is comprised of a top air vent passage formed as a recess in the front face of each brick and extending downwardly from the top face to a lower end located between the top face and the bottom face, and a bottom air vent passage formed as a recess in the rear face of each brick and extending upwardly from the bottom face to an upper end located between the bottom face and the top face. Thus, when one brick is positioned so that its front face abuts against the rear face of another brick lining the kiln, not only are the main air openings of each brick aligned to form the main air conveying channel, but also the top vent passage of one brick is aligned with the bottom vent passage of the other brick to form the desired air vent channel into the interior of the kiln.
Preferably, the air vent channel has a double dogleg configuration to avoid the creation of a direct line of sight path through which heat would be transferred from the kiln interior directly to the kiln shell via radiation. However, each air vent channel could be straight depending on kiln design and/or feed stock being processed. Also, although the top and bottom air vent passages are preferably rectangular-shaped recesses in the front and rear faces of each brick, they may be formed directly through the interior of each brick, for example by boring or casting a hole therein.
Another feature of the invention is the use of key blocks attached to the kiln shell to prevent the refractory bricks from rotating within the shell. These key blocks thus maintain alignment of the air inlet ports in the kiln shell with the main air conveying channel formed in the bricks.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.
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Suspended Refractory Walls and Arches, Bigelow-Liptak Corporation, Bulletin 75-110MRH.
Dock Neil R.
Maciejewski Edward T.
Andrus Sceales Starke & Sawall LLP
Lu Jiping
Suedala Industries, Inc.
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