Improvements in Drying Machinery
Year: 1899

page_text: Date of Application, 4th Feb., 1899-Accepted, 29th Apr., 1899
COMPLETE SPECIFICATION.
Improvements in Drying Machinery
I, OSCAR SCHMEISSER, of 25, Cladowstrasse, Landsberg a/Warthe, Germany,
Engineer, 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:-
With the drying machines at present employed for the drying of such goods
as stoned fruit, cherries, granular substances, etc., in which the goods are placed
within a drum and heated by hot gases, the drum being caused to rotate in
order that the goods may be mixed or agitated by being thrown or rolled off
from the inner lining of the drum and also be continuously fed forward by the
fresh goods entering the machine for the purpose of being dried, certain disad-
vantages are experienced.
At present it is held a matter of importance that the drum should be kept
as full as possible in order to fully utilize it; but the fuller the drum is kept
the less mixing there is, especially at the centre of the material where the goods
are scarcely moved. This is certainly not a matter of great importance with
rough materials or in machines wherein the material is damped; but in machines
where the material to be dried is very sensitive to heat, and, in spite of
this, in which the drying process has to be speedily effected with gases made as
hot as possible, a thorough mixing action is of great importance, as, otherwise,
the materials would be burnt at those parts which first come in contact with the
hot gases whilst remaining damp at the other parts. Of course a constant stir-
ring up or mixing of the material can be effected by rotating the drum more
or less rapidly, but, by this method, such an amount of energy is absorbed that
it is altogether out of proportion to the value of the drying operation; it is
therefore better to fill up the drum to a less extent and to rotate it at a compara-
tively slow speed.
With machines having drums in which the drying gases are caused to pass
more or less obliquely through the materials being dried it appears that, owing
to the varying thicknesses of the layers of material between the inlet and out-
let passages for the gases, these latter make channels for themselves at places
in the material where there is the least resistance with the result that the gases
pass much too rapidly through the material and only at certain places, so that
there is no guarantee that the contents of the drum will be properly dried or the
heat of the gases fully utilized for the drying operation.
Further it also appears, and especially in the larger drying machines, that,
even when the drum is filled to the extent of 50 to 60%, in cross section, the
inner parts of the body of the material are seldom or never mixed, whilst the
drving gases penetrate the material very unequally.
My invention is designed to overcome the foregoing drawbacks by arranging
the drying pipe eccentrically within the drum so that it may be at the centre of
the material which accumulates around it. The drying pipe, which may be of

page_text: any suitable cross-section, is perforated and passes through the drum from end
to end being firmly secured at the outside. The shell of the drum is also per-
forated. The cross section of the tube is preferably arranged to correspond with
the cross-section of the material as it lies in the drum towards one side. By
this arrangement the drying gases can, under the smallest pressure, be applied
simultaneously to all the different layers of the material in its varying positions.
Further, in spite of the drum being only slowly rotated, a greater amount of
material can be dried, under similar circumstances, by the even distribution of
the material round the eccentrically fitted pipe; by the forcing of the material,
which would otherwise be but slightly mixed, across this pipe, and by the con-
sequent better mixing of the whole material.
In order that the said invention may be properly understood I have hereunto
appended an explanatory sheet of drawings, whereon,
Fig. 1 is a cross-section, Fig. 2 a longitudinal section, and Fig. 3 a sectional
plan of the improved drying machine.
On the drawings:-
a is the shell and b, c, and d, e, the ends of the drying cylinder or drum.
The end plates c, e, are not made in one with the ends of the drum but are
separate therefrom and rigidly held in place by the bracket f at one end and
the pipe at the other end. This pipe, which is perforated, is, as shown,
arranged out of the centre line of the cylinder and is carried at the one end by
the plate e and at the other end passes through the plate e and the wall 9 of the
chambers and is held in position by said wall. Its outer end is connected with
a suction fan or exhauster.
The drum a, b, d, revolves upon the rollers and is driven by the gear-
ing k, l, m, n.
If the drum is partly filled with the material to be dried through the funnel o
then, when the drum is rotated, said material, by the centrifugal action, will
accumulate against the side of the shell and roll down or fall over when it reaches
a certain height. In spite of the fact that the material does not, when sectioned,
present a circular section but a semi-circular one yet it has, towards its centre,
little or no movement whilst, at its outside, it has a comparatively large move-
ment. If hot gases are now introduced in the ordinary manner the material
will be dried unequally on account of the deficient mixing and the unequal
thickness of its layers, and, as a consequence, a proportionate amount of time
will be lost in drying the goods properly, If, however, the tube is placed
eccentrically within the drum so as to pass through the middle of the material,
as in accordance with my invention, then the material to be dried will accumulate
at the side in such a manner that the inner parts of the material will be pushed
out of place and the upper parts will form a layer around the pipe as nearly
as possible of an equal thickness throughout; especially is this the case when
the cross section of the pipe h corresponds to the cross-section of the material
(see Fig. 1). The pipe h does not participate in the turning motion of the
drum a, b, d, but remains stationary and the material is caused to constantly
circulate round it with the result that the material is better mixed. It is better
not to force the drying gases into the pipe but to suck them through it becauso
the outer parts of the material, which move with a greater velocity, would then
come first into contact with the hot gases whilst the inner parts, lying round the
pipe h, would only be effected by the gases after they had been partially cooled
and as they rushed rapidly into the pipe, with the result that the inner and
outer parts of the material would practically be submitted to a similar drying
action.
If both, the pipe and the drum a are perforated and if the gases are intro-
duced by the passages q, r, into the closed chamber s, t, g, e, then the gases will
be able to penetrate through the material from all sides at once with practically
equal speed and with the greatest effect, so that, although the capacity of the
drum might be small it would be fully utilized.

page_text: It may be further stated that the drying gases may be sucked out through
the opposite end of the pipe; or through both ends at once.
The drying process may be made continuous by providing a movable door
at d, e, through which the materials already dried can be forced by the intro-
duction of fresh materials through the funnel o.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what
I consider novel and desire to claim is:-
A drying machine having a rotary drum, which may be perforated, with a
fixed pipe arranged eccentrically within the drum, said pipe being perforated so
that the drying medium can pass out from it through the materials to be dried
or in to it from said materials, substantially as hereinbefore described with
reference to the drawings annexed.
Dated this 3rd day of February 1809
H. 1. FITZPATRICK,
100, Wellington Street, Glasgow, Agent.