Improved Means applicable for use in Drying Materials of various kinds.
Year: 1897

page_text: Date of Application, 31st Aug., 1897
Complete Specification Left, 31st May, 1898-Accepted, 30th Nov., 1898
-PROVISIONAL SPECIFICATION.
Improved Means applicable for use in Drying Materials of
various kinds.
I, FRANKLIN DAVID CUMMER, President of the F. D. Cummer and Son Com-
pany, of 616, The Arcade, Cleveland, State of Ohio, one of the United States
of America, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to drying focal and other matter of a solid and semi-
solid character, such as sewage, lignite, superphosphate, cement slurry, &c., and
consists in an improved method of working whereby the operation is expedited,
the output increased, the product rendered more uniform and economy effected.
For the purpose of illustration, I will assume my improved method of work-
ing to be applied in the drying of precipitated and solidified sewage. After
having been pressed into cakes in the usual manner, such material commonly
contains about 65 per cent. of moisture. The cakes, which may or may not
have been roughly broken up, are fed to a revolving drying cylinder of the
kind described in the Specification to my Letters Patent dated 27th August,
1895, No. 16,052. During the passage of the material through the drying
cylinder, a certain degree of disintegration takes place; the smaller pieces and
dust becoming thoroughly dried whilst the larger pieces still contain a con-
siderable amount of moisture. The evaporation which takes place from these
larger pieces acts as a protection to the smaller pieces or particles and prevents
the latter becoming overheated. The material, on being discharged from the
drying cylinder, is screened and the coarser portion, which fails to pass the screen
is returned to retraverse the drying cylinder, until ultimately this portion also
passes through the screen, and is yielded in a suitably dried condition.
One important effect of preventing overheating of the material is to diminish
or obviate the risk of explosion which the drying of certain materials entails,
owing to the liberation of inflammable gases. Moreover, inasmuch as it is
only the dried and finished portion which is actually removed, instead of the
entire charge being delayed until the whole of it is dried, it becomes possible
to largely increase the quantity treated at any given time; and in proportion as
the surface for the absorption of heat is increased, so may the temperature and
volume of the beating gases be augmented. Under these circumstances, a con-
siderably larger quantity of material may be dealt with in a drying furnace of
given capacity, its efficiency being thereby increased, whilst the risk of over-
heating, danger from explosion, and cost of working are diminished.
Dated this 07th date of Aroust 1907

page_text: Improved Means applicable for use in Drying Materials of
various kinds.
I, ERNEST CARTWRIGHT STEAVENSON, of 3, Fenchurch Street, London, E.C.,
Solicitor, administrator of the late Franklin David Cummer, President of the
F. D. Cummer and Son Company, of 616, The Arcade, Cleveland, State of Ohio,
one of the United States of America, Engineer, do hereby declare the nature
of this invention, and in what manner the same is to be performed, to be par-
ticularly described and ascertained in and by the following statement:-
-
This invention relates to a process and means of drying various materials as
hereinafter enumerated and fully described, and the object of the invention is
to so improve and develop the drying process or method hitherto practiced by
the inventor and is now well known, that there can be successfully handled a
number of materials which have hitherto been regarded as practically beyond
the reach of such processes and especially on any such scale as would render
their treatment profitable and practicable for large undertakings, such materials
including city garbage, liquid cement slurry, floated or washed clays, ochres,
umbers and the like in which much the larger percentage of the material may
be in a liquid state and the solids a comparatively small percent. Take, for
example, city sewage, which has never before yielded to a drying process ap-
proaching to this invention because of certain apparently insuperable difficulties
not heretofore overcome. Some of these difficulties have arisen in the
perience of the inventor under the application of his own original processes
and may be enumerated as follows:
ex-
1st: It was found to be impossible with the old method to dry the material
so that in its dried condition it would carry less than fifteen per cent. of moisture
without danger from repeated explosions of the material in the presence of
high temperatures, and as the dried material carrying fifteen per cent. of
moisture would mould and decay after being placed in piles, this result was
entirely unsatisfactory.
2nd With the old process he confidently relied on evaporating 900 pounds
of moisture per hour, but found that if the generated heat was enough to evapor-
ate more than 500 pounds, and if he dried the material below 15% of moisture
he was liable to have repeated and dangerous explosions as already explained.
3rd: Again, was very difficult to so manage the fire in the feeding and
operating of the drier as to deliver the dried material at temperatures below
200° Fahr., or sufficiently low to avoid volatilizing the fertilizing properties of
the sewage.
4th Again, there came from the drier frequently very uncomfortable and
objectionable odors. This occurred always when material inside of the dryer
became over-heated or heated above a moderate temperature, as was liable at
any time to occur.
5th: The drier also delivered into the atmosphere a very large amount of
fine dust which was carried by the wind and air into the houses of residents who
lived near the works, and which, of course, was a very great objection to the
operation of the dryer and clearly demonstrated that the method of handling the
material was as yet imperfect and incomplete, and that the whole process must
be materially improved in order to make it efficient and effective for handling
sewage.
This invention, therefore, consists in the improved process or method of
drying materials hereinafter described, whereby each and all of the several

page_text: obstacles and objections hereinbefore enumerated, and sundry others not par-
ticularized, are wholly overcome and the practicability of the improved process
is demonstrated and established to the entire satisfaction of all who have
given it a trial.
The differences and advantages of the improved method over the old may be
summarized here for contrast and a better understanding of the invention :
1st: After making and testing the improvement it was found to be possible
to deliver the dried material carrying as low as 2% of moisture just as easily
and reliably and continuously as if delivering the dried material carrying a
high percent. of moisture.
2nd: The same dryer has evaporated in this process during a trial test of
twenty-four hours, very accurately conducted, 1750 pounds of moisture per hour
on an average, and it is certain that during the latter part of the run there
was being evaporated more than 2000 pounds of .moisture per hour, or four
times as much as could be safely evaporated until the improvement had been
made.
3rd During a run of over four weeks, night and day, there has not occurred
any fire or explosion whatever, and it is found that the dried materials show
no retrogression, and that it has in its dryest condition every valuable chemical
property which it possessed before its delivery to the drier. The inventor
has found, also, that by reason of this improvement in the process he is enabled
now to dry blood, tankage, garbage, super-phosphates, and all of this line and
class of materials which are very difficult indeed to dry without deterioration
or losses of valuable properties whatsoever; so there is as the result of the im-
provement the double advantage of not only being able to dry the material with
much greater economy and without injuring it in the slightest degree, but
also of doing at least twice as much work in a given time with a plant of a
given size, and of handling materials which by the old process
difficult to handle at best and with meagre results as compared with the
present.
were very
4th: There are now no odors of any kind whatever delivered into the atmos-
phere from the dryer, and during the closely observed test of twenty-four hours
which has been alluded to the dried material left the dryer at a uniform tempera-
ture of about 125° Fahr., although in the final stages of the drying process
the mingled material (the dried and partially dried materials, as will herein-
after appear) passed through at a final temperature of 650 to 700° Fahr. The
moisture in the wet material was mingled with the dry product, so that the
high temperature was not able to affect or over-heat the dried material, although
the dried material (the finest particles of it) carried only about 2% of moisture.
The moisture on the moist material protected the dry.
5th The dust trouble was wholly overcome, and so completely that after work
had gone on night and day for four weeks, an inspection of the roof of the
large works wherein the apparatus was located was made by several of the men,
and it was found that even the gutters, where it was expected that some dust
would be discovered, they were not able to find any, the fact being that no dust
whatever does escape under the present improved operations.
In the accompanying drawings, Fig. 1 is a plain elevation of the improved
drying apparatus.
Fig. 2 is a front elevation thereof, looking inward from the left of Fig. 1.
Fig. 3 is a plan view of the apparatus seen in Figs. 1 and 2.
Fig. 4, Sheet 2, is an elevation of the screen and the distributing passages or
channels therefrom.
Fig. 5 is a plan view, and Fig. 6 is a longitudinal sectional elevation of the
granulating or distributing mechanism shown in Fig. 1 beneath the screen.
The purpose and plan of the machine shown in these several views is to pass
the material through the drying cylinder and thus dry the same more or less
completely, and then passing this dried and partially dried material from the

page_text: cylinder through a screen or separator of some suitable kind to sift out the dry
portions thereof and after subjecting the insufficiently dried portion of the
material to the operations of a granulator or reducer to break it up into small
particles when necessary and carry the same along to be passed again through
the drying cylinder, but with the raw material whatever it may be.
Having reference now to the drawings, the drying cylinder A is shown in
dotted lines, and may be an improved cylinder adapted to do the work, for example,
of the kind described in the Specification of former Letters Patent granted to the late
F. D. Cummer, No. 16052 of 1895, and as is well known in these cylinders the
dried material is fed thereto through the breeching B at the front, which also
forms an exit for the products of combustion or drying agent or gases and
vapor, and the dried or partially dried material is discharged from the rear end
of the cylinder. It is also well known as to the cylinders hereinabove referred
to that the drying agent may enter both through the side and rear end of the
cylinder or wholly through the rear end or side as may be found best, and that
the material travels rearward and the drying agent forward through the
cylinder.
Now, the inventor has found that in the handling of a number of different
materials there are reasons why it is not desirable nor indeed practicable to
so completely dry all the material in a single passage through the machine
as to make it what may be termed commercially dry. Take, for example, city
garbage. He has found by experience that to dry this material by sending
it once alone through the dryer there is not only incurred very great danger
from explosions, but that a very offensive dust is unavoidably carried with the
products of combustion out into the atmosphere, as well as a considerable loss
sustained in the more volatile fertilizing properties which, likewise, are carried
off into the air. Other reasons exist in connection with, other materials for
not drying to a finish in the first passage through the machine, and in all these
materials there is the further consideration. of economy by which it becomes
possible to utilize the full volume of heat from the furnace without waste or
loss to do the greatest amount of drying that can be done with a given quantity
of heat furnished.
These and other considerations have rendered necessary the present invention
to complete the inventor's drying system. He has, therefore, provided means
for screening or sifting the product as it comes from the machine, consisting in
this instance of the rotary screen C to which the material is carried by the
drag conveyor D, the discharge spout d at the rear end of the machine deliver-
ing the material to the said conveyor. From this conveyor the material is dis-
charged into the revolving screen C through spout . The screen C is so con-
structed and arranged that it receives the material at one end and discharges it
at the other, and while this particular screen is circular and revolves, a shaking
or other suitable screen might be substituted for it. Beneath the screen is a
hopper, C, from which lead three several spouts c, c¹, and c², and at the
discharge end of the screen there is a discharge spout to receive the material
which does not sift through and which with the spout e empties directly into
the upper granulator section having casing G. The spout c is supposed to
receive the bulk of the dried material sifted through screen C into hopper C¹,
whence it is discharged into the conveyor F and carried away to any desired
point as finished material. The spout 2, Figs. 1 and 2 deliver a small percent-
age of the material, more or less, to the lower section of the granulator, Fig. 6,
where the operation is as hereinafter described.
H represents an elevator for the liquid material or material in
a fluid or very moist state and whereby the receiving tanks K
and K¹ are kept supplied. There are two drying cylinders, side
by side, and tank for each, 80 that a single elevator serves for
both tanks and the worm L carries the material over to tank K¹ ог
a

page_text: it may flow over by gravity. Delivery spout k supplies the material to the
granulator.
Now referring especially to Figs. 5 and 6, there is shown what is herein
termed a granulator, and which when analyzed is a combined mixer, disintegra-
tor and duster. That is the upper section G of the granulator is used to mix
the materials; the lower section has a series of cutting blades to cut up into
bits the lumps of material coming to it, and the spiral blade following in this
lower section turns the material around and coats the small lumps or bits with
the dust that is fed in through spout c³. More or less dry material comes through
this spout as may be needed for dusting the lumps, and, however refractory
the material delivered from screen C it will be prepared by the granulator for
further handling_in_the_drying cylinder._In_some_cases_a_considerable volume
of dry material through spout will be needed and in others not so much, the
condition of the material as well as other considerations being involved to
determine how much is needed from time to time. The same is true in the
case of spout c, to which the flow of material is governed by valve c¹. Conditions
of fire and quantity and condition of the raw material have especially to do
with the feed through this spout. The feed of raw material through
channel, likewise, depends on certain conditions especially that of the fire.
The operator of the machine cannot be expected to govern the firing, which
may vary considerably during a run, but whatever the fire, whether high or
low, the operator can make the most of the fire he has and get uniformity in.
the product by adapting the quantity of material through both the raw and the
partly dry and dry channels to the state of the fire. With a high heat the
supply of raw material would be increased, and the return stream would be
governed to put this greater flow of raw into the right condition for the dryer,
and so on.
But notwithstanding the fact that varying amounts of dry material
are diverted with the partially dry through the cylinder, the days output of dry
product at last will be equal proportionately to the quantity of wet that has been
carried through the machine.
In the casing or pan G of the granulator are two parallel revolving shafts G¹
and G2, each with blades g which are generally caused to revolve so that the
upper ends of the blades will rotate toward each other. These shafts are driven
from the main shaft M which passes through the lower granulator casing G4
and carries blades m similar to blades y and also a spiral conveyor blade m¹ in
its outer end. Upon the shaft M is a pinion m² meshing with gear g¹ on the
shaft G2 and by the side of this gear is a pinion g² which meshes with a corre-
sponding pinion on the shaft G¹, so that both shafts G¹ and G2 are rotated
at the same rate of speed but in different directions, as before indicated.
In the foregoing construction the material is delivered in two streams simul-
taneously to the granulator, the wet through the spout or pipe from the tank K
ande partly dried from the hopper C¹, with a quantity, more or less as may
be needed, of the dry through spout c. Any suitable valve may be employed
to regulate the flow of the wet through the pipe k, but the stream flowing
through the spout from the screen is continuous and unregulated except as
it may be regulated by the meshes of the screen.
as
From the granulator the material is delivered to the drying cylinder by carrier P
and discharged into the breeching B. However, in a few instances, such
waste carbonate of lime from pulp, paper and scrap work, the wet material
may be passed directly into the cylinder without first being mixed with the dry.
In such cases the partly dried material alone passes through the granulator and
is treated therein, substantially as herein before described.
From the granulator as above described the mixed and dusted material is
delivered into the drying cylinder, where it is dried without making any further
trouble and without the slightest disposition to adhere to the walls or any part
of the machine. Previous to this invention, efforts to deal with many materials were
unsuccessful for the reason that the wet material, owing to its sticky nature,

page_text: would in a short time so fill up the drying machine that it would be rendered
useless.
more
Sometimes it is desirable to have a screen which will make three or
separations, so that each grade of the coarser material as it is returned to the
dryer shall pass through separate disintegrators, and this modification is within
the scope of the present invention. The finest will be the dry or finished
material. The next finest may be dry enough for a finished product so as to be
easily pulverized or considerably more moist than the finest, as may be desired,
and so on, the percentage of moisture increasing as the separated material
increases in size of bits or lumps. In this way the process can be so conducted
that the second grade as to size (next above the finest), as stated before, may
be dry enough to be easily pulverized, and all or practically all of the fine
pulverizing would preferably be done when the material was in the second
condition, as above described, or the process can be so conducted that the material
in the second condition will have dry and moist material mixed, as previously
described, as when there is wanted the presence and influence of the moist
material.
It is obvious that by separating the material by a screen or by other like
means as it comes from the dryer, into two or more grades as to fineness and
by returning to the dryer through separate pulverizers, a gradual reduction and
gradual drying process will be established, and that the period of the drying
process may be prolonged almost indefinitely, although the period of time
occupied by the material in passing through the drying machine at any one
time may be quite short.
With many materials this gradual reduction and gradual drying process may
be effected quite satisfactorily by separating the dried and partially dried
material as it comes from the dryer into two grades as to size, and passing the
coarser through a disintegrator on its way to the dryer and using a disintegrator
of such construction and run at such a speed that only a partial reduction takes
place each time the material passes through the pulverizer or disintegrator on
its way from the discharge to the feeding end of the drying machine; and as
all material which, after leaving the machine, that does not pass through the
screen may be returned to the feed end of the dryer again after passing through
the pulverizer, all of the material will eventually be pulverized fine enough to
pass through the screen, so that by this process the material is gradually dried
and gradually pulverized, although using one pulverizer only.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:
1. The process herein described of drying garbage and different other materials,
consisting in mixing with the fresh or raw material a quantity of more or less
dried material of the same kind and drying them together, substantially as
described.
2. The process of drying materials carrying a high percentage of moisture,
which consists in passing the raw material through a suitable dryer and then
separating out the dry and returning the partially dry material to the dryer
to pass through again with the raw material, substantially as described.
3. The process of treating moist materials like garbage, consisting in drying
the material more or less completely, then separating out the smaller pieces
and dust and passing the rest of the material through the drying process again in
conjunction with the wet or raw material, substantially as described.
4. The process of drying garbage and other materials, consisting in drying
the raw or fresh material along with a quantity of the coarser material which
has been previously passed through the drying process, substantially as described.
5. The process of drying garbage and other materials which consists in passing
through the drying process larger pieces of material which contain moisture,

page_text: together with smaller pieces and dust whereby the latter are prevented from
being overheated, substantially as described.
6. In a drying apparatus, a suitable drying cylinder and means to convey
a portion of the coarser material which has passed through the cylinder back
into the same to pass through again with the raw material, substantially as
described.
7. The drying cylinder, means to divide the material coming therefrom so
as to have the sufficiently dried separated from the insufficiently dried, and
means to mix the insufficiently dried material with the raw material, substan-
tially as described.
8. A drying cylinder constructed to dry moist material, like city garbage,
means to separate the partially dried product from the dried as the material is
discharged from the cylinder, means to carry the said partially dried product
back into the cylinder, and means to-mix said product with the raw material,
substantially as described.
Dated this 31st day of May 1898.
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.