Improved Means applicable for use in Drying Timber and other Materials.
Year: 1897

page_text: Date of Application, 20th Sept., 1897
Complete Specification Left, 4th June, 1898-Accepted, 9th July, 1898
PROVISIONAL SPECIFICATION.
Improved Means applicable for use in Drying Timber and other
Materials.
I, CHARLES ERITII, of 70, Gracechurch Street, in the City of London, Engineer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to improved means primarily adapted for drying timber
but also suitable for drying other materials; the object of the invention being
to properly diffuse heated air through the material, and to automatically regulate
its circulation and humidity so as to avoid injury to the material, while ensuring
thorough and rapid drying; also to ensure economy by automatically regulating
the heat applied in proportion to the absorption of moisture from the material
under treatment.
In a drying kiln constructed according to my improved method, the air is
not discharged until it is so fully saturated as to be of no further use for drying
purposes; and the point of discharge is so situated that the air is most humid
where it first comes into contact with the moist timber or other material, thus
preventing the surface of the moist material from becoming dry until the moisture
has been extracted from the interior, and thereby preventing cracking, surface-
hardening, or other injury.
Assuming my invention to be applied by way of example to the drying of
timber, I construct a room in which the material to be dried is placed, such room
being long and narrow, with doors at each end for the admission of the wet
material and for its discharge when dry. The walls, ceiling and doors are made
as nearly air-tight as practicable, to prevent loss by radiation and leakage. The
floor is open, consisting merely of joists for carrying rails on which trucks loaded
with the material travel through the kiln. Travelling belts or other contrivances
of a similar nature may however be substituted for the rails and trucks.
Adjacent to and preferably underneath the drying room are arranged air-
chambers respectively furnished with heating and reheating appliances. At
the discharging end is the fresh-air inlet, leading to the fresh-air chamber, in
which the heating device is placed, the heated fresh air rising into the upper
room in which the material is contained. A wall divides the fresh-air chamber
A screen
from the reheating chamber, the latter containing the reheating device.
partly divides the reheating chamber from a third chamber, which I call the
return chamber, on the floor of which sand or other absorbing material is placed.
The return chamber is divided from a fourth or vent-chamber by a wall; the
vent-chamber being formed with an outlet or outlets communicating with the
atmosphere.
The working of my drying kiln is as follows:-The fresh-air supply enters
the fresh-air chamber, being induced by the radiation from the heating device,
and diffuses itself through the material and gradually finds its way towards the
loading end, more and more moisture being absorbed from the material as the
current of air proceeds, with consequent loss of temperature, increase of weight,

page_text: and shrinkage of volume of the air. The radiation from the reheating device
compensates for these effects for some distance, but when the air passes the screen
at the end of the reheating device, its increased weight and decreased volume
cause it to descend into the return chamber, the succeeding volume of hotter and
drier air compressing and forcing it downwards directly in proportion to its
absorption of moisture. Sand or other absorbing material being placed on the
floor of the return chamber, much of the moisture is precipitated and drained
away, thereby further cooling the air and augmenting the compressive effect
from above. This air, which is relatively cool but still somewhat moist, is thus
forced under the reheating device until it reaches the wall, where, being checked,
it ascends through the reheating device, and again enters into circulation.
With a view to increasing the cooling effect in the return chamber and the
deposit of the moisture from the air, I provide this chamber with an air-inlet
for admitting a regulated supply of cold air; such inlet being preferably placed
in the side wall near its junction with the wall which divides the return chamber
from the vent-chamber. By these means the degree of humidity of the recircu-
lated air is better regulated to suit the condition and nature of the material under
treatment.
At the loading end of the drying kiln, where naturally the air is most saturated,
the moist air is compressed into the vent-chamber and vent-shafts and passes
thence to the atmosphere instead of into the return chamber, the air at this point
being too moist to have any further value for drying purposes.
It will be evident that the amount of fresh air used varies automatically with
the moisture evaporated; that practically all the heat is utilised; and that the
weather outside has no appreciable effect on the drying process, as the working
of the kiln is entirely regulated by the amount of moisture absorbed from the
wet materials.
Improved Means applicable for use in Drying Timber and other
Materials.
I, CHARLES ERITHI, of 70, Gracechurch Street, in the City of London, 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 :-
This invention relates to improved means primarily adapted for drying timber
but also suitable for drying other materials; the object of the invention being
to properly diffuse heated air through the material, and to automatically regulate
its circulation and humidity so as to avoid injury to the material, while ensuring
thorough and rapid drying; also to ensure economy by automatically regulating
the heat applied in proportion to the absorption of moisture from the material
under treatment.
•
In a drying kiln constructed according to my improved method, the air is
not discharged until it is so fully saturated with moisture as to be of no further
use for drying purposes; and the point of discharge is so situated that the air

page_text: is most humid where it first comes into contact with the moist timber or other
material, thus preventing the surface of the moist material from becoming dry
until the moisture has been extracted from the interior, and thereby avoiding
cracking, surface-hardening, or other injury.
The accompanying drawings represent diagrammatically a kiln adapted for
the purposes of my invention; Fig. 1 being a longitudinal section, and Figs. 2
and transverse sections on the lines 2-2 and 3-3 respectively in Fig. 1.
Assuming my invention to be applied by way of example to the drying of
timber, I construct a room A in which the material B to be dried is placed, such
room being long and narrow, and having doors C C at its opposite ends for the
admission of the wet material and for its discharge when dry.
The walls, ceiling and doors are made as nearly air-tight as practicable, to
prevent loss by radiation and leakage. The floor is open, consisting merely of
joists DD for carrying rails dd on which trucks E, loaded with the material B,
travel through the kiln. Travelling belts or other contrivances of a similar
nature may, however, be substituted for the rails and trucks.
Adjacent to and preferably underneath the drying room are arranged air-
chambers F, F1, F2, F, the two former being respectively furnished with heating
and reheating appliances. At the discharging end is the fresh-air inlet G,
leading to the fresh-air chamber F, in which the heating device f is placed;
the heated fresh air rising into the upper room A in which the material is con-
tained. A wall H divides the fresh-air chamber F from the reheating cham-
ber F1, the latter containing the reheating device f¹. A screen H' partly divides
the reheating chamber from a third chamber F3 (which I call the return chamber)
on the floor of which sand or other absorbing material fo is placed. The return
chamber is provided with a cold-air inlet 2, and is divided from a fourth or
vent-chamber F by a wall H2; the vent-chamber being formed with an outlet
or with outlets f3 f, communicating with the atmosphere by means of flues f¹ f^.
The working of my improved drying kiln is as follows:-
The fresh-air supply, being induced by the radiation from the heating device f,
enters at the inlet G, and, after passing through the fresh-air chamber F, diffuses
itself through the material, and gradually finds its way towards the loading
end C. The air thus becomes charged with more and more moisture as the
current proceeds, with consequent loss of temperature, increase of weight and
diminution of volume. The radiation from the reheating device f¹ compensates
for these effects for some distance; but when the air passes the screen H¹ at
the end of the reheating device, its increased weight and decreased volume cause
it to descend into the return chamber F2, the succeeding volume of hotter and
drier air compressing and forcing it downwards directly in proportion to its
absorption of moisture. Sand or other absorbing material fo being placed on
the floor of the return chamber, much of the moisture is precipitated and drained
away, thereby further cooling the air and augmenting the compressive effect
from above. This air, which is relatively cool but still somewhat moist, is thus
forced under the reheating device f¹ until it reaches the wall H, where, being
checked, it ascends through the reheating device and again enters into circulation.
With a view to increasing the cooling effect in the return chamber F3 and the
deposit of the moisture from the air, I provide this chamber with an air-inlet f³
for admitting a regulated supply of cold air; such inlet being preferably placed
in the side wall near its junction with the wall H2 which divides the return
chamber from the vent-chamber. By these means, the degree of humidity of
the recirculated air is better regulated to suit the condition and nature of the
material under treatment.
At the loading end (C¹) of the drying kiln, where naturally the air is most
saturated, the moist air is compressed into the vent-chamber F3 and the vent-
shafts ff and passes from the latter into the atmosphere instead of into the
return chamber, the air at this point being too moist to have any further value
for drying purposes.

page_text: It will be evident that the amount of fresh air used varies automatically with
the moisture evaporated; that practically all the heat is utilized; and that the
external atmospheric conditions have no appreciable effect on the drying process,
the working of the kiln being entirely regulated by the amount of moisture
absorbed from the wet materials.
my
Having now particularly described and ascertained the nature of said
invention and in what manner the same is to be performed, I claim:
1. In the drying of timber and other materials by passing heated air through
a drying room while the material under treatment traverses the said room in
a contrary direction to the said air, the herein described means for circulating
the heated air, same consisting in providing vent and return ducts at the point
where the air is most humid so that the said air, owing to shrinkage of volume
and increased weight, induces a current of fresh air through the heating device,
and causes a compressive action on the saturated air, whereof a portion is forced
through the vent-chamber, while partially saturated air flows into the return
chamber, and, after depositing surplus moisture, again enters the drying room
through a reheating device, thus establishing a more or less rotary current of
moist air which mingles with the current of hot dry air issuing from the heating
device; the circulation through the dryer varying proportionately with the rate
of absorption of moisture.
2. In a kiln or dryer for timber and other materials of the general character
herein referred to, regulating the humidity of the recirculated air by admitting
a regulated supply of cold air into the return chamber, whereby the cooling effect
and the deposit of the moisture from the returned air may be increased, sub-
stantially as herein described.
3. The herein described means for drying timber and other materials, com-
prising a drying room, provided with an open floor, for receiving the material
to be treated, and a series of air-heating, reheating, cooling and exhausting
chambers arranged beneath the said room, and operating substantially as herein
described.
4. In a kiln or dryer for timber and other materials, the combination, with
a drying room, such as A, of a chamber, such as F, wherein fresh air is heated,
a reheating chamber, such as F, a return or cooling chamber, such as F2, wherein
the moisture laden air from the drying room is precipitated, and a vent or
exhaust chamber, such as F3, substantially as and for the purposes set forth.
Dated this 1st day of June 1898.
UIT
G. G. M. HARDINGHAM,
Chartered Patent Agent, 191, Fleet Street, London, E.C.