APPARATUS FOR DRYING IN VACUO
Year: 1885

page_text: I, HERBERT JOHN. HADDAN, of 67, Strand, in the City of Westminster, Civil
Engineer, do hereby declare the nature of said invention for APPARATUS FOR
DRYING IN VACUO, a communication to me from abroad by Emil Passburg,
Engineer, of Moscow, in the Russian Empire, and in what manner the same is to
be performed, to be particularly described and ascertained, in and by the following
statement:-
The present invention refers to the process, described in the patent specifications
No 6326/1884 and 275/1885, of drying very watery, solid or semi-liquid bodies
in vacuo.
Notwithstanding the employment of a perfect vacuum and the direct introduction
of heat into the bodies to be dried, it solves the problem of carrying out the process
continuously, so that the drying apparatus is constantly fed with the substances
to be dried, and discharges them when dried without the vacuum being destroyed.
At the same time, the apparatus can be so arranged that the feeder may be
hermetically isolated from the drying apparatus,. for the purpose of filling the
feeder from time to time, and that the collecting receivers for the dry products may.
be hermetically isolated from the vacuum.
The apparatus is shown in the accompanying drawing.
As in the original patent, the vacuum-apparatus consists of a horizontal cylinder A
surrounded by a steam-jacket B.
The heat is conveyed, partly by the outer water or steam-jacket A B on the
inner side of which, a; the matérials to be dried move along under the direct
absorption of the heat, (as in the rotary apparatus of the original patent) partly
by means of a water or steam-cylinder D placed in the said vacuum-cylinder, to or
round which is applied the scooping apparatus which turns over the materials.
The tube or heating cylinder D takes, therefore, the place of a heating chamber
placed in the vacuum apparatus.
It is fed with steam or water by the hollow shafts, as in the original patent.
Instead of a cylinder, of course, any other form can be chosen for this inner
-

page_text: It is only essential that the apparatus should rotate and mix up or stir the
material, or that, as shown in the accompanying drawings, a scooping apparatus
should revolve round it; moreover, it must be packed or closed tightly against the
air and the vacuum,
The cylinder A is closed on both sides by the head-plates C¹, and C³.
The inner heating cylinder D is bedded in the journals or shafts a¹ and a³ by
being screwed on to the two hollow shafts and d².
The steam passes from the tube N through the shaft d¹ into this heating
cylinder, and out at the opposite side through the tube N'.
The hollow shafts are rendered air and steam-tight by stuffing-boxes q¹ q³ q³
and *.
A scooping apparatus revolves round, or with this heating-cylinder and consists
of the hollow bearing journals a¹ and a revolving round (or connected with) d'
and d². To the flanges of a¹ and a² are screwed or riveted circular plates b b, and
to these the angle bars c c.
By means of the flat bars g g these rings or discs are united into one system,
which is stiffened by the rings f¹ƒ &°. Bent or straight scoops hh are so arranged
on the flat bars g g, that one scoop projects beyond the following one, by about
one sixth of its length, towards, the outlet E of the drying cylinder A, and thus a
steep screw line is formed round the flat bars gg. By the continued revolution of
these scoops round the horizontal axis of the cylinder A, the materials entering
at E are seized by the scoops hh, then discharged on to the heating cylinder D,
and taken up by the scoops from the heated bottom of the cylinder A, again
emptied on to D, and so on, so that each scoop slightly drives forward the material
it has seized towards the outlet E¹.
It is not absolutely necessary, though permissible, that the scoops should be
arranged somewhat obliquely.
All the parts of the substances to be dried are thus frequently turned over by
this arrangement of the scoops, before they reach the outlet of the apparatus E¹.
By this slow movement of the mass produced by the scooping apparatus, all the
parts of the material are brought into close contact with the heated surfaces.
Hence, even when waste-steam is used as a heating medium in the vacuum
produced by the air-pump, the quick and complete ebullition of the water contained
in the materials takes place without their becoming heated in the vacuum to an
undue degree of temperature.
The vapors developed during the process of drying are carried out of the
apparatus into the condenser & by the pump through the pipes 8282 of the
covers C¹ C³. To the flat bars g g are fastened rotating brushes which
constantly remove any stuff adhering to the casing of the stationary heating-
cylinder D.
The scooping apparatus is made to rotate by means of the pulley R¹ fastened to
the hollow shaft a¹.
Two or more drying-cylinders A and A', can be made to form one apparatus.
The drying apparatus is furnished with a feeding-vessel H¹ and a discharge
vessel H'.
こ
These vessels have man-holes with covers K and K¹ which can be hermetically
closed, observation glasses S and S and air-pump pipes 8³ 8².
H is surrounded by a steam jacket L, with steam-pipe 8° and discharge
pipe 8¹.
The tube M leads to the condenser or the air-pump.
G is a throttle-valve which, by the action of the pulley m, allows the stuff in H'
to fall into the drying cylinder, and then cuts it off.
In the case F F¹ there are wedge-shaped, ground slide valves n n³, made of brass
or other metal, with screw heads p p¹.
By turning backwards the screw-head p, the valve n is made to recede, thus
allowing a free passage into the drying-cylinder A for the stuff thrown out of ¹
through the throttle-valve G.

page_text: י
By turning the screw-head, the valve n is pressed into a hollow wedge-shaped
guide-case, and thus, the drying cylinder A can be hermetically cut off from
H' or H³.
'
[J
F is furnished with a hollow air-tight cover o, so that any stuff can be removed
which may have accumulated here and stick between the slide and the case..
The screw-head p is surrounded by a kind of case, which is hermetically closed
by means of stuffing-boxes.
The following arrangements of the feeding-vessel H' are also advantageous for
large apparatus (Fig II).
For the better preliminary warming of the material, the feeder has, besides the
steam-jacket L, an inner heating-chamber Hs; consisting of two cast-iron tubes R³
and R', screwed together steam-tight.
"
In the annular space between R and R', steam circulates, which enters from L
and again escapes below by a tube into L.
The outer tube R³ has a flange, and is thus suspended to the cover of the feeder
by the screw-bolta.bb and b¹ 61.
A table-shaped frame T, stiffened by a ring R³, serves to support the heating-
chamber.
The lower part of the inner tube R is cast in such a manner that it can be used
as a bed for the fixed collar S³ of the shaft W, and thus as a step-bearing for the
latter.
On the shaft W there is fastened a helix S' or other suitable apparatus, which, as
the shaft W rotates, conveys the material through the narrower neck of the
feeder H to the throttle valve G.
Instead of the latter, a flap valve can be used divided into compartments, or
indeed any apparatus adapted-to control the quantity of the material passing into
the drying cylinder, according to the number of revolutions.
Instead of employing the vertical screw. blade or helix and throttle-valve, the
same effect can, of course, be produced by a horizontal helix, revolving between the
feeder Hand the drying-cylinder A B in a cylinder, and rendered steam-tight by
stuffing-boxes, and allowing the material falling out at one end of the feeder to pass
uniformly through its other end into the drying-cylinder A.
The speed with which the helix rotates is regulated according as the drying-
cylinder requires to be filled.
This arrangement is omitted in the drawing, being simple in comparison with
the parts shown, as it appears sufficient to represent in detail one of the many
arrangements for regulating the feed of the material.
The apparatus represented herewith is suitable for drying all kinds of watery
bodies named in the specification of the original patent, (with the exception of
pappy or viscous substances) but especially for drying starch, bastard-sugar,
brewer's returns and malt. If steam would raise the temperature to a degree
injurious to the material, the casing and inner heating-chamber are heated by
means of water.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
1. A vacuum-drying-apparatus adapted to be fed continuously or periodically
without interrupting its action or destroying the vacuum, said apparatus com-
prising principally one or more drying-cylinders A B furnished with steam-jackets
and connected with a feeder H' and discharge vessel H adapted to be emptied at
the same time as the drying cylinder by means of an air-pump.
2. The arrangement of an inner heating cylinder D for heating by means of
water or steam in the vacuum-drying-apparatus, in place of the beat-reservoirs.
3. The inner scooping apparatus revolving round or with D, composed of flat iron
bars g g, on the outer side of which the scoops h are arranged in a peculiar manner,
for the purpose of bringing the material by their rotation into close contact with

page_text: .
the heated surfaces, and also for moving the mass towards the outlet of the drying
cylinder.
4. The arrangement of brushes 2, on the inner side of the flat iron bars of the
rotary scooping-apparatus, for the purpose of cleansing the heated surfaces of the
cylinder D from the material falling on the same.
5. The wedge-shaped valves n and n¹, with screw spindles, in the case F F¹,
which is furnished with a cover o for the purpose of hermetically cutting off the
connection between the drying-cylinder A and the receptacle H or H2.
6. The rotary throttle valve G and rotary vertical or horizontal helix or screw
blade S', for the purpose of regulating the introduction of the material from the
feeder K¹ into the drying cylinder A.