Improvements in Apparatus for Drying Tea, Grain, Hops, or other Substances.
Year: 1889

page_text: Date of Application, 10th Oct., 1889
Complete Specification Left, 8th July, 1890-Accepted, 9th Aug., 1890
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Drying Tea, Grain, Hops, or
other Substances.
I, SAMUEL CLELAND DAVIDSON of Sirocco Works, Belfast, Ireland, Merchant, do
hereby declare the nature of this invention to be as follows:-
This invention has reference to that kind of apparatus for drying tea, grain, hops
or other substances in which there are a stove or air heater and a drying chamber,
the heated, air from the stove being caused to pass through the drying chamber so
as to act upon the tea or other substance therein, the said substance being itself
caused to travel through the drying chamber.
My improved apparatus comprises first a special form of the stove in which the
hot products of combustion from gas flames or from coke, charcoal or anthracite coal
fires are mixed with the ordinary atmospheric air in such a way that the temperature
of the mixture can be regulated to any required degree and kept thoroughly under
control; and secondly, a drying chamber constructed so that the substance to be dried.
passes through it either as a vertical column or a horizontal layer, and the arrange- ;
ments and devices for passing the material through same being such that the air can
be either driven by a pressure blast or drawn by an exhaust at a very high velocity
and with great force through the material without any of it being blown away as it
passes into, through or out of the drying chamber. The strong air blast which can
thus be employed effects a very rapid rate of drying even with the air at a comparatively.
low temperature.
,
The part of the apparatus which forms the improved stove consists of an outer casing
or bot air chamber enclosing a fire place or hearth the back and sides of which are
closed, the front fitted with fire bars and the top with a flap door or damper which
can be opened or closed as required. A chimney is provided for the purpose of.
carrying away the smoke when lighting the fire or when a fresh supply of fuel is
thrown on.
This chimney is fitted with a damper whereby the draught can be shut.
off as soon as the fire is burning clear, and then the top damper of the fire place is
to be opened more or less so that the products of combustion may pass into the hot
air chamber enclosing the fire place as above referred to, where they become mixed.
with the atmospheric air and heat it up to any required temperature. The heated
mixture of products of combustion and air can then be drawn away by a fan or air
pump and passed through the material in the drying chamber.
The sides and back of the fire place are constructed with cast iron plates lined
with fire-clay tiles, and the open front has movable fire-bars and a fire door above
them, and the bottom of the fire place is preferably laid as a hearth with fire brick.
The damper door on the top of the fire place consists of a cast iron movable damper
or door which is raised and lowered by chains attached to pullies or levers keyed on
a shaft one end of which is fitted with a handle and a ratchet wheel and pawl or
equivalent device, so that the extent of opening can be regulated as required. The
outer casing or air chamber enclosing the stove has openings for admitting the cold
air freely in its lower part opposite the back and sides of the fire place whence it
ascends through the air spaces between the outer casing and the fire place to the top
of the air chamber, where it meets and mixes with the hot products of combustion
emerging from the fire through the more or less open top damper door.
The part of the apparatus which forms the improved drying chamber consists
according to one form of its construction, of a hollow vertical column of rectangular
section the front and back of which are usually about six inches apart and constructed
with perforated metal plates. The material to be dried fills and gradually passes
down through the space between these plates, while the heated or desiccated air is

page_text: forced through from back to front of the column by means of a fan or air pump.
When using this pressure blast and to prevent the material being blown out of the
column through the openings by which it enters or is discharged from same, about
twelve inches at the top and bottom of the side of the column are made with solid
plate instead of being perforated, so that there is a considerable weight of material
between where the air enters through. the perforated plates and said inlet and outlet
openings. The perforations in the plates for letting the blast into the material are
much smaller in area than the perforations in the plates through which it escapes.
An appliance is fitted to the exit or delivery opening by which the amount of
material discharged can be regulated, and I preferably use a horizontal plate held
close to the bottom of the column by spring steel suspension straps and to which a
to and fro motion is imparted by a crank or excentric; an opening in front of the
column at the bottom allows the material to be carried out on the plate on its forward,
stroke and said opening is fitted with a sliding door so that by raising or lowering
it the quantity of material discharged can be regulated. Other arrangements such
as a fluted roller may be used for the delivery of the material should its special nature
prevent its working satisfactorily with the first described arrangement.
+
Another alternative arrangement of the drying chamber consists of a travelling.
band on which the material is carried in a deep layer through a horizontal flue with
a large air chamber above and below the travelling band, the upper air chamber
being connected by an air duct or pipe with the hot air supply chamber. of the stove,
and the lower air chamber being connected to an exhaust fan. When the exhaust
fan is at work it creates a partial vacuum in the lower air chamber to fill which the
hot air from the stove rushes down through the material on the travelling band, and
to prevent a strong inrush of air through the openings for inlet and outlet of the
travelling band the top air chamber should be higher than the hot air generator, and it is,
essential that the air ducts through the stove and between it and the drying chamber
be sufficiently large to allow the hot air to flow into the top air chamber very freely
and under a slight pressure from the stove so that the fan may draw its supply of hot
air with less resistance through the air ducts than through the inlet and outlet
openings for the travelling band; hence there is no inrush of air through the latter
of sufficient force to displace material on the band, while at the same time a very
strong air current is being drawn down through the material, which. produces an.
exceedingly rapid rate of drying. I preferably construct the travelling band with
narrow strips of sheet metal laid across its length and carried on chains running on
rollers; the ends of said strips are turned up so as to form a flange along the edges
of the band for the purpose of keeping the material from going over at the sides,
and their surface is perforated to allow the air to pass through them. The chains or
links to which the strips are attached slide along. rests or guides to prevent the band
sagging down between the end rollers.
· Dated this 10th dose of Dotohar 1880.
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Patent Agent..
"
COMPLETE SPECIFICATION.
Improvements in Apparatus for Drying Tea, Grain, Hops, or
other Substances.
I, SAMUEL CLELAND DAVIDSON of Sirocco Works, Belfast, Ireland, Merchant, 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
1.
This invention has reference to that kind of apparatus for drying, tea, grain, hops
or other substances in which there are a stove or air heater and a drying chamber,
the heated air from the stove being caused to pass through the drying chamber so as
to act upon the tea or other substance therein, the said substance being itself caused
to travel through the drying chamber.

page_text: My improved apparatus comprises first a special form of the stove in which the hot
products of combustion from coke, charcoal or anthracite coal fires are mixed with
the ordinary atmospheric air in such a way that the temperature of the mixture can
be regulated to any required degree and kept thoroughly under control; and secondly
a drying chamber constructed so that the substance to be dried passes through it
either as a vertical column or a horizontal layer, and the arrangement and devices
for passing the material through same being such that the air can be either driven
by a pressure blast or drawn by an exhaust at a very high velocity and with great
force through the material without any of it being blown away as it passes into,
through or out of the drying chamber. The strong air blast or current which can
thus be employed effects a very rapid rate of drying even with the air at a comparatively
low temperature.
The part of the apparatus which forms the improved stove consists of an outer
casing or hot air chamber enclosing a fire place or hearth the back and sides of which
are closed, the front fitted with fire bars and the top with a flap door or damper
which can be opened or closed as required. A chimney is provided for the purpose
of carrying away the smoke when lighting the fire or when a fresh supply of fuel is
thrown on. This chimney is fitted with a damper whereby the draft can be shut off
as soon as the fire is burning clear, and then the top damper of the fire place is to be
opened more or less so that the products of combustion may pass into the hot air
chamber enclosing the fire place as above referred to, where they become mixed with
the atmospheric air and beat it up to any required temperature. The heated mixture
of products of combustion and air can then be drawn away by a fan or air pump and
passed through the material in the drying chamber.
The sides and back of the fire place are constructed with cast iron plates lined
with fire clay tiles, and the open front has movable fire bars and a fire door above.
them, and the bottom of the fire place is preferably laid as a hearth with fire brick.
The damper door on the top of the fire place consists of a cast iron movable damper
or door which is raised and lowered by chains attached to pullies or levers keyed on
a shaft one end of which is fitted with a handle and a ratchet wheel and pawl or
equivalent device, so that the extent of opening can be regulated as required. The
outer casing or air chamber enclosing the stove has openings for admitting the cold
air freely in its lower part opposite the back and sides of the fire place, whence it
ascends through the air spaces between the outer casing and the fire place to the top
of the air chamber, where it meets and mixes with the hot products of combustion
emerging from the fire through the more or less open top damper door.
The part of the apparatus which forms the improved drying chamber consists
according to one form of its construction of a hollow vertical column of rectangular
section the front and back of which are usually about six inches apart and con-
structed with perforated metal plates. The material to be dried fills and gradually
passes down through the space between these plates, while the heated or desiccated
air is forced through from back to front of the column by means of a fan or air
pump. When using this pressure blast and to prevent the material being blown out
of the column through the openings by which it enters or is discharged from same,
about twelve inches at the top and bottom of the column are made with solid plate
instead of being perforated, so that there is a considerable weight of material between
where the air enters through the perforated plates and said inlet and outlet openings
respectively. The perforations in the plates for letting the blast into the material are
much smaller in area than the perforations in the plates through which it escapes.
An appliance is fitted to the exit or delivery opening by which the amount of
material discharged can be regulated, and I preferably use a horizontal plate held
close to the bottom of the column by spring steel suspension straps, and to which a
to and fro' motion is imparted by a crank or excentric, an opening in front of the
column at the bottom allows the material to be carried out on the plate on its
forward stroke and said opening is fitted with a sliding door, so that by raising
or lowering it the quantity of material discharged can be regulated. Other

page_text: arrangements such as a fluted roller may be used for the delivery of the material
should its special nature prevent its working satisfactorily with the first described
arrangement.
Another alternative arrangement of the drying chamber consists of a travelling
band on which the material is carried in a deep layer through a horizontal flue with
a large air chamber above and below the travelling band, the upper air chamber
being connected by an air duct or pipe with the hot air supply chamber of the stove,
and the lower air chamber being connected to an exhaust fan. When the exhaust
fan is at work it creates a partial vacuum in the lower air chamber to fill which the
hot air from the stove rushes down through the material on the travelling band, and
to prevent a strong inrush of air through the openings for inlet and outlet of the
travelling band the top air chamber should be higher than the hot air generator, and
it is essential that the air ducts through the stove and between it and the drying
chamber be sufficiently large to allow the hot air to flow into the top air chamber
very freely and under a slight pressure from the stove so that the fan may draw its
supply of hot air with less resistance through the air ducts than through the inlet
and outlet openings for the travelling band; hence there is no inrush of air through
the said openings of sufficient force to displace material on the band, while at the
same time a very strong air current is being drawn down through the material which
produces an exceedingly rapid rate of drying. I preferably construct the travelling
band with narrow strips of sheet metal laid across its length and carried on chains
running on rollers; the ends of the said strips are turned up so as to form a flange
along the edges of the band for the purpose of keeping the material from going over
at the sides and their surface is perforated to allow the air to pass through them.
The perforated plates forming the travelling band slide along rest or guides to prevent
it sagging between the end rollers.
The accompanying drawings illustrate the construction of the apparatus.
Figure 1 is a front elevation of the stove or air heater and of the drying chamber,
the latter being in the form of a hollow vertical column. Figure 2 is a vertical
section on the line c-d of Figure 1. Figure 3 shows the back of the stove and a
vertical section through the centre of the drying chamber. Figure 4 is a plan of
the apparatus, the vertical column being in section on the line ab of Figure 1.
Figures 5, 6 and 7 show the arrangement of the drying chamber in which the
material to be dried is passed through in a horizontal layer and the blast drawn down
through it by means of an exhaust fan.
Figure 5 is a longitudinal vertical section, Figure 6 a vertical cross section and
Figure 7 a plan.
Referring first to Figures 1, 2, 3 and 4 the following letters indicate the different
parts
A. Fire place of the stove.
A2. Cast iron plates forming sides and tops of fire place.
A³. Fire clay tile lining to sides and bottom of fire place.
B. Fire bars.
B. Fire door.
C. Hinge damper.
C2. Shaft with chain pullies for raising and lowering hinge damper.
D. Handle for turning shaft C².
D2. Ratchet and pawl to hold shaft C in any fixed position.
E. Smoke chimney.
E2. Smoke box with cleaning door.
E. Brick base for chimney to rest on.
E. Damper in chimney for shutting off the draft.
F. Enclosed space around fire place or hot air chamber.
F. Opening at bottom of hot air chamber for admission of atmospheric air.
G. Hot air duct.

page_text: 3. The combination of parts forming a drying chamber or apparatus and com-
prising a travelling band on which the material to be dried is carried as a horizontal
layer through the chamber from end to end, while hot or desiccated air is drawn
down through said material by a fan or other exhausting apparatus, substantially as
herein before described and represented in the accompanying drawings.
Dated this 8th day of July 1890
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Patent Agent.