Disc ash conditioner

Apparatus for uniformly wetting and discharging ash. It is enclosed in a dust hood. It comprises an open top pan disposed at an angle of about 55.degree. degrees with respect to a floor, rotated at slow speed. An ash charge chute discharges ash into the pan. Fixed scraper means extend at right angles to the pan to scrape the bottom of the pan while water is sprayed onto the surface of the discharged ash so that the rotated ash is tumbled back to the bottom of the pan to effect uniform wetting of the tumbled particles as they are discharged downwardly from the top of the side of the pan.

This invention relates to a rotating disc ash conditioner. 
BACKGROUND OF THE INVENTION 
One of the major requirements of smoke stacks is the requirement to remove 
sulfur dioxide (SO.sub.2) gas from the combustion gas stream. This is 
generally accomplished by spraying a lime solution into the gas stream. As 
the small droplets of lime solution come into contact with the sulfur 
dioxide in the gas stream, the calcium in the lime solution reacts with 
the gas sulfur dioxide to form calcium (CsSO.sub.4) and calcium sulfate 
(CASO.sub.3) which are solids that can be removed by dust collectors. 
There is also unreacted lime (CaO) which is removed by the dust collectors 
along with the combustion fly ash. 
Before the sulfur dioxide scrubbers were installed, the fly ash could be 
conditioned with a water addition in a paddle or drum mixer. While these 
units did a marginal job, it was acceptable and low in cost. With the ash 
from sulfur dioxide scrubbers, the lime, calcium sulfide and calcium 
sulfate together with the fly ash all of which are very fine particles 
make the blend of materials act like a pozzuolanic or portland cement. 
When water is added in a paddle mixer, the fly ash begins to set and 
hardens so that the paddles are constantly wearing against the hardened 
cement liner and causing breakdowns. 
SUMMARY OF THE INVENTION 
An object of the present invention is to overcome the above-mentioned 
problems by utilizing a disc pelletizer with a special right angular plow 
arrangement in a continuous line across part of the face of the pan and 
totally enclosing the pan of the disc pelletizer, whereby an ash 
conditioner is provided that does not release any dust, has very little 
wear and produces a uniformly conditioned fly ash.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1 and 2, numeral 1 denotes a dust hood for enclosing the 
rotatable pan, which dust hood has a door 2 and an inlet chute 3 for 
receiving fly ash and feeding it to a rotatable pan 6 having a cylindrical 
wall 7. The pan 6 has a hub 4 and stiffeners 5, better shown in FIGS. 
7-12. 
More of the plows or scrapers are located in a continuous line across the 
face of the pan and have an augularly disposed end plow. The plows 10 are 
located at right angles to the mesh 6a covering the bottom of the pan 6 so 
that they scrape mesh 6a of the pan and so that they interfere with the 
flow of the fly ash as it is carried up the face of the pan. This 
interference causes the fly ash to tumble, particularly because of the 
substantially critical 55.degree. degree angularity of the pan with 
respect to the floor thereby opening or spreading the individual particles 
so that a water spray 12 can wet each particle. The sorting or 
classification action of the disc pan makes the larger, wet particles rise 
to the top surface of the bed of ash and keeps dry or unwet particles from 
exiting the pan. This action insures that all of the particles are wet 
before they discharge from the pan. 
The side wall 7 of the pan 6 is coated with non-stick material such as a 
product named BR-3s sold by Normac, Lisle Illinois or a product known as 
Tyvar 88 made by Menasha Corp. of Fort Wayne, Ind. or a product named 
Durall 55 of RMS Corp., Lawrence, PA. The non-stick coating reduces the 
friction of the scrapers on the side wall, thereby reducing the power 
required to rotate the pan. 
The plows or scrapers 10 are manufactured of very abrasive resistant 
refractory mounted by gluing them to a rigid steel plate 11. 
FIG. 6 shows how the rigid one inch mounting plates 11 are grooved to 
insure that the glue adheres to the steel mounting plate. While many 
structural adhesives would perform this function, however a preferred 
product is produced by Ciba-Geigy; under the trademark Araldite AV138 with 
Hardener HV998. The refractory blockor plow 10 is bolted to the steel 
mounting plate 11 in addition to being glued to the plate. The wear 
surface of the plow can be any type refractory material. 
An alumina-zirconia-silica cast refractory containing 45 to 55% by weight 
of aluminum oxide sold under the trademark "Monofrax" produced by 
Carborundum Corporation performs very satisfactorily. The refractory needs 
to be thick to resist the wear of the pan bottom. A three (3) inch 
thickness functions very well. 
Referring to FIGS. 3, 4 and 5, tubes T.sub.1 and T.sub.2 are welded to the 
rigid steel plate 11 and are supported and are laterally adjustable by 
tube T.sub.4 through a clamped plate. As can be seen in FIG. 4, tubes 
T.sub.1 and T.sub.2 are slotted at 14 of the bolted supports 13 so they 
can be adjustably lowered or raised with relation to the pan bottom 
without removing the clamping bolts. The back of the support tubes T.sub.1 
and T.sub.2 is braced by a plate 19 which is welded to tube T.sub.3. This 
support allows the scrapers to take large shock loadings. 
The pan 6 of the disc pelletizer ash conditioner is mounted on the low 
speed shaft of a gear reducer 15 of driving motor 16 as shown on FIG. 2. 
As shown in FIGS. 7 and 8, pan mounting hub 4 is held onto the low speed 
shaft with a taper lock bushing or a bored-to-size hub. The plate on the 
pan mounting hub is match drilled with the pan mounting flange 8 shown in 
FIGS. 9 and 10. The pan mounting flange is attached (welded) to the pan as 
shown in FIGS. 11 and 12. The large mounting flange permits shimming 
between the pan mounting hub and the mounting flange to insure that all 
points of the pan bottom plate are in the same plane as it rotates about 
the low speed shaft of the reducer. 
The pan slope shown in FIG. 2 is preferably about 55.degree. degrees from 
the horizontal. This slope is best for tumbling the ash so it can be wet 
by the water spray. Other slopes will not be as satisfactory, but they 
will perform to some extent. 
The rotational speed of the pan has been found to be best at 5 to 6 RPM for 
an 8' diameter pan. For best mixing, the depth of the pan has been found 
to be: 
EQU d=D.sup.0.65 
where: 
d=depth in inches and 
D=pan diameter in inches. 
Other depths can be utilized, but this depth seems to provide the best 
mixing and the proper retention time. 
The discharge point from the pan is arranged so that the conditioned 
material exiting over the edge of the pan drops through the open bottom 3a 
of the enclosure and onto a conveyor below. (not shown) This arrangement 
insures that there is no build-up of material inside the enclosure. 
While I have illustrated and described a single specific embodiment of my 
invention, it will be understood that this is by way of illustration only 
and that various changes and modifications may be contemplated in my 
invention within the scope of the following claims.