Improved Method of Vulcanizing and Drying Wood.
Year: 1894

page_text: Date of Application, 9th Aug., 1894-Accepted, 22nd Sept., 1894
COMPLETE SPECIFICATION.
Improved Method of Vulcanizing and Drying Wood.
I, CHARLES HOWARD, of 927 Park Avenue, New York City, N.Y., United
States of America, Chemist, 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 :-
My invention relates especially to an improved method of treating wood, and
bas for its object the provision of a method, and means for carrying said method
into effect, whereby lumber, timber and woods of all kinds and descriptions may
be quickly and thoroughly vulcanized and dried, and at the same time so treated
as to preserve the fibre of the wood intact, preventing rupture thereof, and
splitting during the carrying out of the process.
To attain the desired end, my invention consists essentially in enclosing the
Iumber, timber or wood to be treated, while in a cold condition, in an air tight
cylinder, exhausting the air from the cylinder, and forming a vacuum therein;
then applying heat to the cylinder, thus causing the moisture contained in the
wood to escape therefrom, vaporizing, and breaking the vacuum; after the vacuum
is broken, applying air pressure and heat, which is maintained a sufficient time to
cook the wood being treated, and finally circulating the air, and taking out the
moisture, thereby gradually reducing the temperature and pressure, all of which
will be hereinafter first fully described, and then pointed out in the claims.
Heretofore, attempts have been made to vulcanize and dry wood, &c., but the
methods employed have been more or less defective; as if the wood to be treated
is enclosed in an air tight chamber, and pressure and heat applied at the same time,
the surface of the wood is dried, and the high heat employed causes the wood to
crack and split, and the rapid generation of steam from the moisture contained in
the pores of the wood, causes a rupture of the fibre, and the product of such a
process is of a very inferior quality. By my improved method of treatment, these
difficulties are overcome, and the quality of the product under my treatment is
greatly enhanced in value. My first step is to enclose the wood to be treated in
an air-tight cylinder, and then exhaust the air; this causes a portion of the
moisture within the wood to be drawn to the surface, while leaving the albuminous
constituents of the sap of the wood therein. After maintaining the vacuum for a
time, heat is applied by means of suitable circulating pipes within the cylinder,
and such heat vaporizes the moisture of the wood until the vacuum is broken, and
all such action is of so gentle a nature as to leave the fibres of the wood in a
perfect and unruptured condition. The heat coagulates the albumen, &c., contained
in the sap, leaving the same within the wood to act as a preservative. By now
applying air pressure and heat, which are maintained for some time, the wood
becomes thoroughly cooked. In order to gradually and gently reduce the pressure,
and at the same time cool off the wood, I cause a circulation of the air to take
place, through the cylinder, and condenser around the heating furnace and when
the pressure has been brought down to the atmosphere, the wood is properly
vulcanized, dried and cooled, and is in a perfect condition.
Various kinds of apparatus may be employed for carrying my method into effect,
that shown in the accompanying drawing illustrating substantially what is required.
In said drawing,
Fig. 1 is a plan view of a plant for vulcanizing and drying wood in accordance
with my invention.

page_text: Fig. 2 is a front elevation of the cylinders, one of which has the door removed.
Similar numerals of reference, wherever they occur, indicate corresponding parts
in both the figures.
1, 1, are air-tight cylinders, made of any approved material and shape. 2 is a
door, hinged at 3, and arranged to close the end of the cylinder. 4 is a screw,
projecting from the door. 5 is a screw-threaded hub, mounted on the screw 4, and
provided with arms 6 arranged to engage with perforated ears, 7 upon the cylinders.
30 are manipulating arms upon the hub. This arrangement provides effective
means for closing the cylinder. 8 are rails within the cylinder, designed to support
a car, 9, upon which the lumber to be treated is placed, as particularly illustrated
in Fig. 2 of the drawing. 10 are pipes, placed within cylinders 1, and com-
municating with any source of steam supply through the medium of a pipe 11.
12 is a valve arranged for drawing any precipitated moisture &c., from the bottom
of the tank 1. 13 are blow-off, or relief valves, located in the top of the
cylinders, 1.
From the rear of the cylinders 1 I lead pipes 14, provided with valves 15, and
communicating with a pipe 16, which passes through a condenser 17. From the
air pump, 18, a pipe 20 leads to an air receiving and moisture precipitating tank, 21,
arranged in the well known manner, and a pipe, 22, leads from this tank 21 through
a heater 31, and to branch pipes 23, communicating with cylinders 1. 24 are
valves located in the branch pipes 23, and 25 are blow-off valves. 26 is a valve in
pipe 16 arranged to open into the atmosphere. 33 is a pipe which passes from
pipe 22 around the heater 31, whereby air may be circulated through the cylinders, 1,
and the heater cut out.
In carrying my method into effect, the air pump 18 is employed to exhaust the
air from the cylinders 1, through a relief valve 32, in order to create a vacuum
within said cylinders, and after the heat has been applied to the cylinders, in
carrying out the treatment, as hereinabove described, this pump is employed for
creating an air pressure within the cylinders 1, and in maintaining the circulation
through the cylinders and condenser after the wood has been sufficiently cooked,
thus gradually cooling the wood at the same time the pressure is gently reduced to
atmospheric.
In obtaining the vacuum, (which of course is not complete) the valves 24 in the
branch pipes 23 are closed, and the valve 32 at the pump 18 is opened. After the
vacuum has been maintained the requisite length of time, the valve 32 is closed
and also the valves 15, preventing the escape of air from the cylinders. The heat
is now applied, breaking the vacuum, by reason of the expansion of the cold air
still remaining in the cylinder and wood, and also by reason of the expansion and
vaporization of the moisture therein, and then the pump 18 is started, creating a
pressure in the cylinders 1. After the wood has been subjected to this heat and
pressure as long as is necessary, the heater is cut out, valves 15 opened, and the
pump 18 causes a circulation of the air through the cylinders and condenser,
removing the moisture, cooling the air and wood, and gradually reducing the
pressure to the normal.
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. The herein described method of vulcanizing and drying wood, that is to say;
first enclosing the wood in a cold condition in an air-tight cylinder, exhausting the
air from said cylinder; applying heat to the cylinder until the vacuum is broken;
then creating an air pressure within the cylinder, maintaining the same until the
wood is sufficiently vulcanized, and then circulating the air and reducing the
temperature, substantially as set forth.
2. The herein described method of vulcanizing and drying wood, which consists
in enclosing the wood to be treated, while in a cold condition in an air-tight
cylinder; exhausting the air from the cylinder and forming a vacuum therein;

page_text: applying heat to the cylinder, causing the moisture contained in the wood to
vaporize and break the vacuum; then creating air pressure within the cylinder
while the heat is maintained, and finally circulating the air through the cylinder
and through a condenser whereby the moisture is removed from the circulating
air and the pressure and temperature are gradually reduced, substantially as set
forth and described.
C. HOWARD,
Per W. H. Beck,
115, Cannon Street, London, Agent.