Improvements relating to Rotary Drying, Pulverizing, and Evaporating Machinery.
Year: 1893

page_text: Date of Application, 19th Aug., 1893-Accepted, 28th July, 1894
Improvements relating to Rotary Drying, Pulverizing, and
Evaporating Machinery.
I ADALBERT VON PODEWILS, Manager of the Podewils Fäkal Extract
Manufactories of Burklein Strasse No. 14/0 Munich in the Empire of Germany
do hereby declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
L
Many waste or refuse materials in towns, fæcal matters, meat, bones, blood and
manure, slaughter house, fish and vegetable refuse, and also old leather, wool, feet,
bed feathers and other matters require high temperatures for being dried and
pulverized and where a rotating drum is used for treating such materials, the drum
with its end covers and axles must work under a high steam pressure and heavy
load, consequently the end covers especially have to withstand great strains, not only
from the steam pressure but also from the moving forces and stresses resulting from
rotary movement of the axles.
For the purpose of attaining especially with regard to the latter point, a solid
construction which at the same time allows of the covers being heated and
expanded under heat and pressure these latter are made each of a pair of contrarily
directed conical or spherical dish shaped plates a whose bases are turned towards
each other as shown on the annexed drawings representing the apparatus in which
Fig. 1 is a longitudinal section.
The hollow axles are connected with the end covers by rivetting one of the dish
shaped disks ou the axle or on a flange thereon while the other disk is provided
with a stuffing box through which the axle passes. The covers are consequently
allowed to freely expand laterally under high pressures while the outer axle end is
well supported and retained horizontally projecting from the drum.
On the exterior end of the hollow axles 1 stuffing boxes m m are provided
serving to form an airtight connection with the pipes leading into the interior of
the drum and the end covers respectively.
The driving or gear wheel Z placed on one of the axles could also be arranged
or fixed directly upon the cover itself. Liquids are introduced by the tubes which
pass through the hollow axles of the drums, while semi liquid matters are intro-
duced by manholes before the apparatus is put in motion.
In order to enable the pipe p, which serves usually for the passing off of the
steam and vapours generated in the drum, to be used also for drawing off liquids
out of the drum, this pipe which usually turns upwards in the drum is made
rotatable and is provided with a strainer or filter n.
This latter in order to prevent
choking up is provided with a steam blow out pipe r..
If found necessary the pipe p
may also be furnished with a strainer n' in the interior of the drum. The liquid to
be drawn off is drawn through the pipe V into the receiver d by a suction pump or
in any known way. The receiver d may also serve, by means of pipes V and p, for
the filling of the apparatus with any liquid to be evaporated, while semi-liquid
bodies are introduced into the apparatus from a receiver d' through the manholes
by the aid of the filling chute v. Fig. 2 represents a vertical cross section through
the apparatus showing the rotatable pipe p.
Through the pipes y¹ y² y³ (Fig. 1) steam is admitted into the covers a a and the
heating body s; this steam passes again through y' in the form of condensed
water.
Bios 3 and 4 represent
5
drving drum made of cast iron. On account of its

page_text: large weight only the interior cylinder a is rotated while the exterior & remains
stationary.
The axle bearings are provided in the covers of the outer cylinders b. The
heating steam is admitted where convenient to the outer cylinder, and the
condeused water is led off at any suitable place below. Liquids are introduced by
the pipe d. The pipe p is rotatable as in Fig. 1 and serves for carrying away the
generated steam and liquids. Solid bodies are introduced by the manholes provided
above.
To discharge the drum the heating steam is cut off and when consequently a
vacuum originates within the heating space 1, the lower manhole of the exterior
cylinder as well as the manhole of the inner cylinder are opened. The lower manhole
of the outer stationary cylinder 6 is not visible on the drawing. The contents of the
drum may then be discharged through said manholes.
The pulverization of the solid residue in the drum is produced when necessary
simultaneously with the drying within the drum and may be effected by use of
freely moving hard bodies or cylindrical rollers.
However the disadvantage of incrustation of the heating surface under high
temperature is very great and this incrustation would tend to be increased by use
of simple rollers as the latter would press the soft material to be dried against the
heating surface so as to adhere thereto.
In view of this fact, these cylindrical rollers must at the same time be made so as
to serve as scrubbers. For this purpose the freely rotating combined disintegrators
and scrubbers g g shown in Figs. 3 and 4 may be used. The devices shown in
Figs. 3 and 4 will illustrate how the scraping contrivances act; these latter consist
of solid and heavy links of a rectangular cross section, possessing however on their
sides channelled recesses h h.
The single pieces 9 are put into each other like the links of a chain, so that the
whole scraper represents a chain with limited movability.
The speed of the rotating drum is chosen so that sliding or slipping motion as
well as tipping over of the chain happens sometimes. Thereby it is attained that
each of the four edges of each link are alternately acting on the inner surface of
the drum. At both sides the chain could be provided with closing pieces or end
pieces which take up or receive the pushes against the drum covers.
By the continuous sliding and rolling on the inner wall of the rotating drum, a
constant scraping action takes place while the edges formed by the recesses and
the slightly sloped surfaces of the scrubbers are continuously sharpened by the
same action, the separate rolling links acting therefore continuously but alternately
as sharp heavy-scrubbers. If desired filling blocks may be inserted and rivetted in
the recesses of the scrubbers as shown on the left of Fig. 4, to lessen or modify
their scraping effect. The outer surface of the drum may be scraped by a scraper
arranged to press against it along its length as shown in Fig. 4 or 7 and as
generally fitted to rotary driers of this nature.
Where the drum is not heated by steam but by the direct gases from a furnace
there is the danger that in case incrustation occurs on the heating surface the
material will begin to burn. The before described scrubbers prevent incrustation
so long only as the drum is rotated. It is of great importance that alarm should be
immediately given when stoppage of the drum occurs and that the fire be at once
damped.
For this purpose the following device is employed. As shown in Fig. 6 the druin
is actuated by the shafts m² and n² the bevelled wheel m³ on the shaft m²; the bevelled
pinion m is thus actuated (Fig. 5) and the latter drives the governor 2. In case
the drum stops from any cause the governor rocks the bell crank lever 63 and
releases the rod a² which closes the smoke damper a³ in the flue a and opens the
steam whistle a'. This alarm signal calls the attendant and at the same time the
fire is damped.
The druin shown in Fig. 5 is heated by direct firing gases and merely consists of
a rotary cylinder. This cylinder is set in masonry so that its whole surface is

page_text: made usuable as heating surface. Through the hollow axle, pipes pl p² are led
at both sides by which latter on the one hand filling and discharging of the
cylinder take place, and on the other hand the generated steam is drawn off by any
suitable pump.
Furthermore in one of the front covers another man-hole (not shown in the
drawing) is provided through which eventually filling and discharging may also be
effected.
Fig. 7 represents a vertical cross section through the middle of the apparatus,
Fig. 8 a vertical cross section through the fire box K.
To further increase the safety of action of a drum rotating in fire gases, it must
be prevented as far as possible that any unintended stoppage occurs at all. For
this reason, the end covers and the axle bearings should be protected against too
intense heating, resulting from the fire gases.
If these portions however are placed outside the masonry, there would be too
great a cooling of the covers, so that a part of the cylinder surface, serving as heat
surface would be lost. If one the other hand only the axle bearings are placed
outside the walling, the covers must then be necessarily arranged so far back that
they are protected from the direct action of the heat gases by a second walling.
However by this construction the axles would become excessively long.
To suit these threefold requirements, namely
1. To protect covers and axle bearings against too intense heat,
2. To protect the covers against too great cooling and avoid the loss of heating
surfaces,
3. To avoid the use of too long axles,
the covers are placed in special end chambers d¹ and projecting into the latter a
casings (Fig. 5) is built to receive the axle bearing.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is.
1. In a drying or combined drying and pulverizing apparatus a rotating drum with
the arrangement of end covers adapted to be heated, consisting of two conical or
spherical dish shaped disks a arranged base to base, the axle of the drum being
rivetted to one of the two said disks and connected by a stuffing box b with the
other, the said drum being also provided with a pipe p guided through one of the
axles and rotatable so that it may be used with or without a strainer n or n¹ for
carrying either vapour or liquid.
g
2. A pulverizing and scrubbing apparatus comprising scrubbers 9 of rectangular
or prism shaped cross section with channelled recesses whose edges constitute
scrapers adapted to be kept sharpened by the wear and tear caused by their rotating
motion within the cylinder.
3. To increase the safety of action of a drum rotating in fire gases, the
combination of this drum with a closing or shutting arrangement a³ which on
stoppage of the drum is released by the aid of a governor and thus closes the
smoke flue a' and causes at same time an alarm device to be actuated.
4. To secure the rotation of a drum rotating in the fire gases, the arrangement of
the.end covers in fore chambers d¹ provided with casings s projecting into the said fore
chambers in which casing the axle bearings are placed, all substantially as illustrated
and described and for the purposes set forth.
Dated this 10th day of A 1000
R. HADDAN.
Herbert Haddan & Co.,
18, Buckingham Street, Strand, London, Agent for Applicant.