IMPROVEMENTS IN MACHINERY OR APPARATUS FOR DRYING LIMESTONE, SUGAR, CEREALS, AND OTHER LIKE MATERIALS."
Year: 1881

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
"t
& Co., Patent Agents, Southampton Buildings, London, for an Invention
of IMPROVEMENTS IN MACHINERY OR APPARATUS FOR DRYING LIMESTONE,
SUGAR, CEREALS, AND OTHER LIKE MATERIALS." A communication from
abroad by The International Pavement Company, Incorporated, of Hartford,
Connecticut, United States of America.
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 16th June 1881.
LIKE
WILLIAM ROBERT LAKE, of the Firm of Haseltino, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN MACHINERY OR
APPARATUS FOR DRYING LIMESTONE, SUGAR, CEREALS, AND OTHER
MATERIALS." A communication from abroad by The International Pavement
Company, Incorporated, of Hartford, Connecticut, United States of America.
This Invention relates to improvements in machinery or apparatus especially
designed for heating and drying crushed limestone which is to be mixed with
melted asphaltum in the formation of plastic compositions to be subsequently
moulded and formed under pressure into blocks for street pavements or analogous
purposes. The said machinery or apparatus may however with advantago be
employed for drying or evaporating the moisture from cereals, sugar, and other
materials.
My improved apparatus consists generally of a hopper, into which a mass of
crushed limestone or other material is placed; a screw conveyor; a drying cylinder,
which receives the materials from the said conveyor and is provided with mechanism
for rotating it, and with a helical channel or guide from end to end along its
interior surface, so that the limestone or other material will by the rotation of the
said cylinder around its axis be conveyed through such cylinder; a furnace for
heating air in a chamber, which chamber encloses the rotating cylinder; devices
for enabling such heated air to enter the drying cylinder, and in circulating

page_text: through the same absorb the moisture driven off from the material; a flue cominu-
nicating with the interior of the drying cylinder, a chimney for carrying off the
vapor charged air, and a chuto for enabling the dried stone or other material to bo
discharged from the drying cylinder.
In the accompanying Drawing,-
Figure 1 is a side elevation partly in section of my improved machinery or
apparatus, and
Figure 2 is an end view partly in section on the lines x, x, and y, y, of the
same.
Figure 3 is a transverse section of the drying cylinder drawn to an enlarged
scale.
A is a hopper, into which the material to be dried is supplied in any con-
venient manner. The bottom of this hopper is contracted and communicatos with
the groove or channel of a screw conveyor B. This conveyor is caused to revolve
by means of power applied to a pulley on its shaft a, or by any other convenient
means, and being situated within the cylindrical case b connecting the hopper
with the drying cylinder C, it follows that any material entering from the hopper
into the spiral channel of the conveyor screw will be forced by the revolution of
the said screw into the drying cylinder. This device is very similar in principle to
that used in flour mills for conveying meal received from the mill spouts to the
elevator. I may, however, substitute for this conveyor any other suitable
conveyor.
The drying cylinder C is enclosed by a casing C' of brick-work or other suitable
material so as to be within an air-chamber H. The said cylinder is adapted to
be revolved around its axis by suitable mechanism which may be applied in any
preferred manner, and in order that the material to be dried may enter at one end
of the cylinder and the moisture driven off by heat may be discharged at the other
end of the said cylinder, the journals c, c', attached to the heads of the cylinder
are made tubular so as to constitute loose slip-joint connections with the cylindrical
case 6 of the conveyor at one end, and with the discharge pipo or chimney D
at the other end. By this construction the case b and the chimney D may remain
stationary while the drying cylinder revolves but remains in connection with
them.
Suitable bearings c² for these journals c, c', may be set in the end walls of the
casing C', but I prefer that the tubular bearings should rest on friction roller c³,
in which case simply loosely fitting collars may be arranged at c³.
The interior surface of the drying cylinder C is provided with a spiral channel &
formed of a vertical plate of twelve inches in height (more or less) secured at one
edge of the inner surface of the cylinder, and arranged in a spiral line from the
receiving to the discharging end of the said cylinder, and at intervals there may
be placed across the spiral channel shelves or ledges E, Figure 3, over which the
material to bo dried may be tumbled as the cylinder is revolved, so as to be better
exposed to the heated air circulating through the said cylinder. At the end of the
spiral channel an opening is made through the shell of the drying cylinder, which
opening communicates with a chute F for discharging the material which has been
dried. In place of setting the axis of the drying cylinder in a horizontal plane
and providing its interior surface with a spiral channel. the said cylinder may be
set with its axis in a plane inclined to the plane of the ground, and the spiral
channel can then be dispensed with, but the arrangement shewn in the Drawing
is preferable.
The air in the chamber which surrounds the drying cylinder is heated to the
requisite temperature in any convenient or preferred manner by a furnace G or
by steam pipes. To admit this heated air into the cylinder to afterwards circulate
through the same and take up and carry away the moisture driven off from the
material undergoing the drying operation the shell of the drying cylinder is
perforated with a series of holes ffroin two to three feet apart, or thereabouts, around

page_text: its whole surface, and into these holes are inserted pipes g, say, one inch in
diameter, which extend radially inward toward the axis of the cylinder for a
distance of from six to twelve inches beyond the walls of the spiral channel d, so
that none of the material can escape from the said cylinder through such pipes.
It will be found advisable in practise to stay these pipes by securing them by
clasps and rivits to the walls of the channel.
The crushed limestone or other substance or material to be dried is by the
revolution of the drying cylinder caused to travel through the spiral channel d
from the receiving to the discharging end of the cylinder, and being subjected to
the influence of heat from the furnace the moisture which it contains is driven off
in the form of vapor. The heated air in the air-chamber surrounding the drying
cylinder flows into the cylinder through the entrance pipes g, and absorbs this
moisture while the draught through the discharge pipe D, which may be connected
with the chimney of the furnace, not only causes the air from the air-chamber H
to be drawn into the cylinder and circulate through it, but also carries off the
same after it has become charged with vapor. For drying some substances, such as
limestone, for example, for use in making paving-blocks, it will not be necessary
to prevent the shell of the drying cylinder from being exposed directly to the
flames of the furnace, or exclude some of the smoke-gases and other products of
combustion from entering the drying cylinder. For drying other substances,
however, such as cercals, for example, it is important that none of the products of
combustion should find entrance to the drying cylinder, and therefore if the
apparatus is to be used for drying any material which would be injured by smoke
or gases the air-chamber should have no direct communication with the furnace.
A convenient arrangement in such a case will be to make use of steam for heating
the air-chamber, the steam being conducted through lines of pipes laid along the
walls of the chamber, and leading from and returning to any suitable steam
generator.
In the apparatus above described it is necessary that means should be provided
for supplying air to the air-chamber, not only for the purpose of maintaining an
inflowing current to the drying cylinder, but also to enable the temperature of the
air within the drying cylinder to be lowered at pleasure in caso from any cause
the heat has become greater than is required for drying. In drying crushed
limestone for use in the manufacture of concrete composition for paving blocks, if
the stone becomes calcined from the effect of a too high degree of heat in the
drying cylinder it will be greatly impaired in value as a constituent for such
composition. Accordingly, to furnish a supply of air to the air-chamber, maintain
a circulation within the drying cylinder, and also incidentally to reduce the
temperature within the cylinder, if desired, the air-chamber is provided with any
preferred number of doors I arranged at convenient intervals, in which doors if
preferred register valve openings may be made whereby the outer air may be
admitted into the air chamber, and the heat within the drying cylinder be
regulated.
Having thus fully described the said Invention as communicated to me by my
foreign correspondents and the manner of performing the same, I wish it understood
that I claim,
First. The combination, substantially as above set forth, of a hopper for con-
taining material to be dried, a conveyor, a revolving drying cylinder constructed
to receive the material from the said conveyor and pass it through the cylinder, a
discharge chute to carry off the dried material, an air-chamber enclosing the drying
cylinder, pipes for enabling the air-chamber to communicate with the interior of
the said drying cylinder, and a chimney for carrying off the vapors evolved from
the material during drying.
Second. The combination, substantially as above set forth, of a revolving drying
cylinder provided with a chimney, an air-chamber enclosing the said cylinder
pipes connecting the interior of the latter with the air-chamber, and doors or

page_text: apertures to admit the external air into the air-chamber to maintain an air circu-
lation within the said drying cylinder, and to onable the temperature within the
same to be regulated.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Sixteenth day of June, in the year of our Lord One
thousand eight hundred and eighty one.