Improvements in Vacuum Drying Apparatus.
Year: 1889

page_text: "Date of Application, 15th June, 1889
Complete Specification Left, 14th Mar., 1890-Accepted, 19th Apr., 1890
PROVISIONAL SPECIFICATION.
Improvements in Vacuum Drying Apparatus.
We JOSEPH BROWN of Plantation Starch Works, Manufacturer, and GEORGE
JOHNSTON of 29 Eaglesham Street, Engineer, both of Glasgow, in the County of
Lanark, North Britain, do hereby declare the nature of this invention to be as
follows:
This Invention which relates to improvements in vacuum drying apparatus consists
as follows.
We employ a large cylindrical drum or casing of malleable iron or other suitable
material, having closed ends, but provided with the necessary openings for the inlet
and outlet of the material to be dried, as also openings for shaft, pipes, and other
working parts. This drum is mounted on its one end in any suitable way, and is
provided on its outside with an inlet feed hopper on the top, and a discharge hopper
on its bottom. The said hoppers being formed as an ordinary tapered cock, but
having its water or key-way only cut partially through and along its plug, the said
key way being preferably of a Ù shape in section, so that on the material being put
into the hopper, which is formed on the top side of the cock, it falls into and fills the
key-way, and as the said plug revolves by means of gearing, preferably by belts and
pulleys, the material is carried round with it till it falls through the opening formed
in the underside of the cock, the upper opening having meanwhile been closed by the
uncut portion of the tapered plug, and thus the vacuum formed is preserved. To
facilitate the free run of the material from the key-way when required, I place a
light fraune or moveable bottom along the key-way, the said frame having a projecting
rod at either end, and the rods formed with eyes, through which passes two spindles,
the said spindles working in holes formed across the plug at right angles to its
centre line. The spindles being formed near their one end with a collar for allowing
a spiral, or other spring to work against, the other ends of the spindles working
against the sides of the cock, so that at the proper time the spindles with frame are
allowed to be pushed forward by the springs owing to their entering into two grooves
or checks formed on the inside of the cock, thus tending to start the freeing or
running of the material when required.
After the material has passed through the feed hopper, it falls inside the drum,
and on to a circular tray of iron or other suitable material, which is provided on its
underside with a steam chamber the said tray being formed with a circular opening
at its centre, for allowing a perpendicular shaft to revolve, and also another opening
or slot extending from said central opening to the side or edge of the tray; this
opening being for the purpose of allowing the material on being moved round to
fall through on to another similar tray underneath, there being a number of these
trays mounted inside the drum at certain intervals from top to bottom, and having
their openings or slots arranged spirally downwards so that the material after being
moved round the top of the uppermost plate falls through its slot on to the top of
the next plate, and again on the material being moved round this plate it falls through
its slot on to the plate underneath, and so on till it reaches the bottom where it gets
discharged through the outlet or discharge hopper.

page_text: To obtain the necessary movement of the material round the said trays, I mount a
perpendicular shaft inside the said drum at its centre, the said shaft being carried up
by a thrust block of brass or other material, this thrust block being held in a suitable
bearing, either formed on, or fixed by any suitable means to the bottom of the drum,
which has a scrow therein for adjusting, that is, raising or lowering, the thrust block
and with it the shaft. The top end of this shaft passes through an ordinary packed
stuffing box and gland formed on the top of the drum where it is driven by spur,
toothed, bevel, or worm gearing, suitable means being provided for allowing the
shaft to move perpendicularly as desired. This shaft carries a number of cross bars
of iron, or other material, the said bars having a number of curved plates or scrapers
attached to them for the purpose of moving the material round, and so arranged
that while the curved points of the scrapers on the one half of the bar point to the
circumference of the drum, those on the other half point towards the centre of the
drum, thus causing the material to be moved round in a zig-zag fashion, one or more
of these bars being provided for each tray, the whole being adjustable by the screw
at bottom end of the shaft. The said adjusting may be assisted by two or more small
windows in the sides of the drum so arranged one directly opposite the other as to
allow of what is going on in the inside to be seen from the outside by the party in
charge.
The whole interior arrangement working in a vacuum which may be kept up by a
suitable pump or pumps, or their equivalents, the said pumps also withdrawing the air
passed into the cylinder or drum, at each revolution of the cocks, as well as any
leakage and condensed steam.
The steam necessary for heating purposes may be caused to pass into the steam
chambers either consecutively, or in series, or separately, so that, by applying an
ordinary Thermal trap, which is placed outside the drum, the temperature in the
various steam chambers may be regulated at will.
In order to assist the evaporation, the heating surface of the drum may be increased
by an external steam jacket.
Dated this 14th day of June 1889.
JOHNSONS,
115, St. Vincent Street, Glasgow, Petitioners' Agents.
COMPLETE SPECIFICATION (AMENDED).
Improvements in Vacuum Drying Apparatus.
We, JOSEPH BROWN, of Plantation Starch Works, Manufacturer, and GEORGE
JOHNSTON, of 29 Eaglesham Street, Engineer, both of Glasgow, in the County of
Lanark, North Britain, 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, that is to say: :-
Our said Invention relates to the drying of various materials with the aid of a
vacuum, and has for its object to improve the construction and operation of the
apparatus employed.
In carrying out our Invention we employ a vertical cylindrical drum or casing
which is connected with pumps or other suitable exhausting apparatus, and is provided
with inlet and discharge appliances for the materials operated on, such appliances
being contrived to interfere as little as possible with the vacuum inside of the drum.
Within the drum there is a series of horizontal steam-heated annular trays upon which
the materials to be dried are stirred and carried round by scrapers or rakes made to
rotate about a vertical axis. The trays are made with openings through which the
materials fall from each tray to the next lower one, the several openings being
disposed in spiral order and retrogressively as regards the direction of rotation of the
scrapers so that the materials falling on each tray are carried completely round it
before reaching the opening in it through which they descend to the next lower tray.
And in order that our said Invention and the manner of performing the same may

page_text: be properly understood we hereunto append two sheets of explanatory drawings to be
hereinafter referred to and representing our improved apparatus.
Figures, 1, and 2, on sheet, 1, of the drawings are a plan and a borizontal.section;
and figure, 3, on sheet, 2, is a vertical section. Figures, 4, 5, and 6, are vertical
sections of the inlet appliance. In these drawings the same reference letters are used
to mark the same or like parts wherever they are repeated.
To
The vertical drum or casing of the apparatus is constructed of steel or iron boiler
plate and consists of a cylindrical shell, A, with flat top and bottom ends, B, C, the
interior being connected by a pipe, D, with pumps or exhausting apparatus.
assist in sustaining the atmospheric pressure on the ends, there is centrally placed a
stationary vertical shaft, E, having its ends entered into sockets in ribbed
plates, B1, C1, fixed centrally on the insides of the top and bottom; and a screw
spindle, E 1, having a handwheel on it, is applied for adjusting the shaft, being
worked through an internally screwed eye in a plate, C2, fixed to the bottom, C,
of the drum.
Inside the drum there are placed at regular distances one above the other, a series
of annular trays, F 1, to F 10, each consisting of a hollow casting strengthened with
outer and inner steel or wrought-iron belts, G, G 1, and supported by vertical
bars, G 4, or in any other convenient way. Each tray casting is made with internal
radial partitions having passages at their inner and outer ends alternately and thus
forming a tortuous passage for the steam with which the trays are heated. The steam
may be admitted first to the interior of the topmost tray, F 1, by a pipe, G 2, and may
thence pass successively through the others passing from each one to the next through
a connecting pipe, G 3; or the steam may be supplied separately to each tray, or to
any number of the trays as may be found most advantageous in practice.
Immediately above the trays there are a number of scrapers or rakes, H, which are
fixed on horizontal bars, H 1, those on alternate trays being placed at right angles to
each other, and moved round in the direction of the arrow in figure, 2, so as to stir
and carry round the materials on the trays. The scrapers, H, are inclined in plan to
the bars, H 1, the inclination of one set of scrapers on each tray being such as to
move the materials outwards, whilst the inclination of the opposite set is such as
to move the materials inwards; and the innermost scraper of each outward moving
set and the outermost scraper of each other set are adjusted to work in contact or
nearly so with the inner and outer rims respectively of the trays so as to prevent
materials from adhering to the rims. The scraper bars, H 1, are carried and turned
by a vertical angle-iron bar, J, which at its top and bottom ends is bolted to brass
blocks, J1, J 2, fitted to turn upon the central vertical shaft, E. The brass blocks, J 1, J 2,
are made in halves bolted together upon the shaft, E, which is made with collars
fitting counterpart grooves in the brass blocks, to sustain the weight of the parts
attached to the brass blocks. The upper brass block, J 1, has fixed on it a spur-
wheel, K, with which there gears a pinion, K 1, on a shaft, K 2, extending through a
stuffing box to the outside of the drum and there geared by bevil wheels, K 3, to a
horizontal shaft, K 4, having on it a pulley, K 5, for a driving belt. By means of the
mechanism just described the brass blocks, J1, J2, with the angle-iron bar, J, connecting
them is made to rotate at a suitable speed, and to carry round the scraper bars, H 1,
and scrapers, H. The scraper bars, H 1, are not rigidly fixed to the vertical angle-
iron bar, J, but are secured thereto by bolts passing through elongated holes so that
the scrapers independently take their proper positions upon the trays.
The materials to be operated on by our improved apparatus may be any granular,
powdered, fibrous, bran-like, or similar matters in a wet or moist condition. For
introducing the materials into the drum there is provided at the top a combined
hopper, L, and valve, L 1, the valve part being made to some extent like a
conical-plug stopcock. The parts are shown in longitudinal vertical section in
figure, 4, and in transverse vertical section in figures, 5, and 6, the valve or
plug, L 1, being shown in different positions in the latter figures.
No passage
is formed completely across or through the plug, but it is made with a trough-
like cavity, L2, at one side, which receives the materials when turned up as

page_text: in figures, 4, and 5, and drops them into the drum when turned down as in
figure, 6. As moist materials are apt to adhere to the inside of the cavity, L2, a
plate, L3, is arranged in an inner recess to move downwards when the cavity, L 2, is
turned downwards, and start the descent of the materials. This plate, L 3, may be
acted upon by a spring which is compressed when the cavity is turned up but is free
to act when the cavity is turned down, a projection on the plate being acted on by a
cam groove in the socket of the plug. It is however preferable to take advantage of
the different directions of the pressure acting on the plug or valve, L1, when in its
two positions; and for this purpose there is arranged in the inner recess behind the
plate, L3, a spring in the form of a cell, L4, of thin flexible and resilient metal like
that used for pressure gauges, this spring cell being fixed to the plate, L3, and to the
back of the recess and having its interior in communication with the outside of the
plug. When the plug is turned with the cavity, L2, downwards, the atmospheric
pressure acting inside the cell, L 4, makes it expand and push the plate, L3, down-
wards; but when the plug is turned with the cavity upwards the interior of the
spring cell, L4, being then in communication with the partially vacuous interior of
the drum the cell collapses and draws the plate, L. 3, into the recess. A similar valve
appliance, L 5, is used for discharging the inaterials from the bottom of the drum, but
in it the interior of the spring cell, 4, is put in communication through the plate, L 3,
with the cavity, L2. The inlet and discharge valves or plugs are made to rotate
continuously at suitable speeds by means of short shafts, L 6, having on them
pulleys, L 7, for driving belts.
The materials as they are admitted at the top fall on the uppermost tray, F1, and
are moved round upon it by the scrapers, H, until, having made nearly a complete
circuit, they reach and fall through an opening, M. in the tray. Each tray, F 1, to F10,
is made with a similar opening, M, and the several openings, M, are arranged in
spiral order retrogressively as regards the direction of rotation of the scrapers, H, so
that the materials are moved round upon each tray before descending to the next
lower one.
Having now particularly described and ascertained the nature of our said Inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
1. The improved vacuum drying apparatus the parts of which are combined
substantially as hereinbefore described and as shown in the accompanying drawings.
2. The combination of a vertical series of horizontal annular steam-heated trays
having spirally disposed openings, with rotating scrapers, all arranged and operating
substantially as herein before described.
3. Appliances for introducing and discharging the materials each comprising a
rotating conical plug or valve having a cavity in one side provided with a spring-
controlled plate to insure the emptying of the cavity, substantially as hereinbefore
described.
Dated this Thirteenth day of March 1890.
EDMUND HUNT,
Applicants' Agent.