Slagging rotary kiln

An improved kiln wherein a smile shaped oil cooled refractory support is shortened so its distal end is adjacent the outside end of a front nose ring on a rotatable kiln drum, the nose ring being extended radially inwardly to shield the distal end of the smile shaped support from radiant energy from the kiln drum and direct combustion air over the distal end of the smile shaped support to prevent thermally induced stress cracking and substantially reduce the amount of partially burned material that spills over the front nose ring.

BACKGROUND OF THE INVENTION 
The invention relates to a rotary kiln and more particularly to an 
improvement in the front wall refractory support and the rotary kiln 
adjacent thereto. 
The kiln front wall refractory support member, referred to as the smile, 
has a history of failures which necessitated costly kiln downtime and 
repairs. In addition the end of the kiln adjacent the feed chute, called 
the nose ring, allowed partially incinerated waste material to spill over 
into the air inlet damper requiring frequent removal and reburning of the 
spilled material. 
The front wall refractory support, referred to as the smile because of it 
appearance from within the kiln, is made of mild steel and has oil 
passages disposed therein for cooling the structure. It supports 
refractory that protects the front wall from temperatures between 
1500.degree. F. and 220.degree. F. which exist in the kiln due to the 
introduction of solid charges of waste into the kiln. The front section 
has been an area requiring continuing repair. The high temperatures cause 
accelerated corrosion due to oxidation. During the three years the 
incinerator has been in operation, the smile area has been replaced once 
and repaired numerous times. The failures were due to cracks in the smile 
which allowed oil to escape into the kiln. To repair the cracks the kiln 
had to be shut down and allowed to cool so the cracks could be ground out 
and seal welded. 
SUMMARY OF THE INVENTION 
Among the objects of the invention may be noted the provision of reduced 
potential of smile failures and reduction of spillage of unburned waste 
material in the air inlet damper. 
In general, an improved kiln for burning waste having a rotatable 
refractory lined kiln drum with a raised front nose ring and a front wall 
with a smile shaped oil cooled refractory support cantilevered from the 
front wall to support a cantilevered refractory portion. which extends 
into the rotatable kiln drum , when made in accordance with this 
invention, comprises reducing the length of the smile shaped oil cooled 
refractory support so that its distal end is adjacent the edge of the 
front end of the front nose ring of the rotatable kiln drum; increasing 
the height of the nose ring so that it extends radially inwardly beyond 
the lower portion of the smile shaped oil cooled refractory support; and 
cantilevering the cantilevered refractory portion that extends into the 
rotatable kiln drum beyond the smile shaped front wall support structure 
and over the heightened nose ring, whereby combustion air flows past the 
smile shaped oil cooled refractory support to provide cooling, increase 
the life thereof and substantially reduce the amount waste running over 
the front nose ring.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings in detail, and in particular to FIG. 1, there 
is shown a portion of a slagging rotary kiln 1 having a refractory lined 
rotatable kiln drum 3 and a front refractory wall 5 having a smile shaped 
oil cooled steel support 7 cantilevered from the front wall 5 for 
supporting a refractory heat shield 9 which extends into the refractory 
lined kiln drum 3 to protect the front wall 5 from the heat energy 
generated in the kiln drum 3. 
As shown in FIG. 2 the refractory heat shield 9 has a waste inlet chute 11, 
a burner opening 13 and an inspection opening 15 disposed therein. The 
refractory lined kiln drum 3 has a raised front nose ring 17 forming a dam 
on the front end thereof. A combustion air duct 18 is disposed adjacent 
the front wall 5 and a damper (not shown) is disposed under the smile 
shaped oil cooled refractory support 7 to provide combustion air to the 
kiln drum 3. 
FIG. 3 shows the improvements made in the kiln 1 and comprise reducing the 
amount of cantilever or length that a smile shaped oil cooled refractory 
support 7A extends from the front wall 5 into the kiln 1 so that the 
distal end thereof is generally adjacent the front edge of a front nose 
ring 17A. The height of the nose ring 17A is extended radially inwardly so 
that its inner edge is radially inward of the lower portion of the smile 
shaped support 7A. In the embodiment shown, the front nose ring 17A is 
formed of a castable refractory material. The radial inner edge of the 
nose ring 17A is notched to form a step 19 to provide clearance between 
the smile shaped support 7A and the nose ring 17A. 
The smile shaped support 7A also has a plate portion 21, which is 
cantilevered out from its distal end to provide support for applying a 
castable refractory material 23 that will extend into the rotary kiln drum 
3 and protect the front wall 5 from the heat generated in the kiln drum 3. 
Once the castable refractory material 23 has cured, the plate portion 21 
is expendable as the cured castable refractory material 23 will support 
itself over such a short cantilevered span. 
The combination of moving the distal end of the oil cooled smile shaped 
support 7A away from the kiln drum 3, passing combustion air over the 
distal end of the smile shaped support 7A and raising the height of the 
nose ring 17A cooperates to shield the distal end of the smile shaped 
support 7A from the radiant energy generated in the kiln drum 3 and 
directs relatively cool combustion air over the distal end of the smile 
shaped support 7A to cool it and inhibit thermal induced stress cracking 
of the smile shaped support 7A. The combination also helps prevent 
partially burned material from flowing over the nose ring 17A and into the 
inlet air duct. When slag rings do occur with this combination of 
improvements it can be melted out with out causing excessive temperature 
excursions occurring in the smile shaped support 7A. In the first month 
after installation of the modifications approximately 1.1 million pounds 
of solid material has been destroyed in the incinerator and during this 
period only about 800 pounds of material has come over the front nose ring 
which is less than would spill over in one hour before the modifications 
were made. No failure of the smile shaped oil cooled refractory support 7A 
has occurred since the modifications have been made. 
While the preferred embodiments described herein set forth the best mode to 
practice this invention presently contemplated by the inventors, numerous 
modifications and adaptations of this invention will be apparent to others 
skilled in the art. Therefore, the embodiments are to be considered as 
illustrative and exemplary and it is understood that the claims are 
intended to cover such modifications and adaptations as they are 
considered to be within the spirit and scope of this invention.