IMPROVE- MENTS IN BAKING OR DRYING GYPSUM AND IN KILNS OR OVENS FOR THIS AND OTHER PURPOSES
Year: 1878

page_text: LETTERS PATENT to Robert Thompson, of Victoria Chambers, Wigan, in the
County of Lancaster, Consulting Engineer, for the Invention of "IMPROVE-
MENTS IN BAKING OR DRYING GYPSUM AND IN KILNS OR OVENS FOR THIS AND
OTHER PURPOSES."
Sealed the 13th June 1879, in pursuance of an Order of the Lord Chancellor, and
Tote
Sealed the 13th June 1879, in pursuance of an Order of the Lord Chancellor, and
dated the 6th November 1878.
PROVISIONAL SPECIFICATION left by the said Robert Thompson at the Office
of the Commissioners of Patents on the 8th November 1878.
ROBERT THOMPSON, of Victoria Chambers, Wigan, in the County of Lancaster,
Consulting Engineer. "IMPROVEMENTS IN BAKING OR DRYING GYPSUM, AND IN
KILNS OR OVENS FOR THIS AND OTHER PURPOSES."
This Invention has for its object improvements in baking or drying gypsum, and
in kilns or ovens for this and other purposes.
For these purposes I form that part of the kiln or oven which supports the ma-
terials with plates set at an inclination and overlapping each other like louvre
boards, having spaces between. I pass a current of air which has been previously
heated through these spaces, and so the heated air is admitted to the kiln or oven.
The air rises amongst the materials to be baked or dried and escapes at the top of the
kiln or oven.
By means of this inclined support the materials as they are baked or dried are
caused to pass towards openings in the kiln or oven through which they will be taken
away.
The temperature of the air is regulated to suit the material to be operated upon,
and the quantity of the heated air is also regulated to hasten or retard the process
of baking or drying the materials.
The regulation of the temperature may be effected by the admixture with the hot
air of cooler air, and the entrance of the cooler air in suitable quantity may be con-
trolled by automatic or other means.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Thompson in the Great Seal Patent Office on the 14th June
1879.
ROBERT THOMPSON, of Victoria Chambers, Wigan, in the County of Lancaster,
Consulting Engineer. "IMPROVEMENTS IN BAKING OR DRYING GYPSUM AND IN
KILNS OR OVENS FOR THIS AND OTHER PURPOSES."
This Invention has for its object improvements in baking or drying gypsum, and
in kilns or ovens for this and other purposes..
For these purposes. I form that part of the kiln or oven which supports the ma-
terials with plates set at an inclination and overlapping each other like louvre
boards, having spaces between. I pass a current of air, which has been previously
beated, through these spaces and so the heated air is admitted to the kiln or oven.
The air rises amongst the materials to be baked or dried and escapes at the top of the
kiln or oven.
By means of this inclined support the materials as they are baked or dried are
caused to pass towards openings in the kiln or oven through which they will be taken
away.
The temperature of the air is regulated to suit the material to be operated upon,
and the quantity of the heated air is also regulated to hasten or retard the process
of baking or drying the materials.
The regulation of the temperature may be effected by the admixture with the hot
air of cooler air, and the entrance of the cooler air in suitable quantity may be con-
trolled by automatic or other means.
In order that my said Invention may be most fully understood and readily
carried into effect I will proceed to describe the Drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
circular kiln or
vertical section
show the regu-
front clevation,
Figure 1 is an elevation and Figure 2 is a vertical section of a
oven adapted for baking or drying gypsum; Figure 3 is also a
showing a portion of the same to a larger scale; Figures 4, 5, and
lating apparatus, Figure 4 being a side elevation and Figure 5 a
both partly in section; Figure 6 is a plan with some of the parts removed.
a, a, are the walls of the kiln or oven; b is the mouth or feeding opening at the
top, and c, c, are the drawing openings around the bottom; d, d, are inclined
overlapping ring plates of cast iron which line the side walls at the lower part of
the kiln or oven. Heated air is admitted to the space between the walls a and the
rings d, and it issues into the body of the kiln between the rings and by perforations
suitably provided, as the Drawings indicate.
e, e, are similar inclined overlapping ring plates built up into a cone in the middle
of the kiln, and from the interior of the cone and between these rings also heated air
is admitted.
It will be remarked that the form of the rings d and e is such that the air
inlets are sheltered and kept clear of the descending material, and that this material
by hanging against the projecting lips will be caused as it moves down to turn about
and expose all its surfaces to the air.
The hot blast stoves and blowing apparatus employed in the manufacture of iron
are suited to supply heated air to these kilns or ovens. The size of the blowing
apparatus and stoves are of course adapted to the number of ovens or kilns to be
supplied and to the volume and pressure of blast required. A very light pressure of
blast will suffice.
In baking or drying gypsum in a kiln or oven such as the Drawing represents,
and, say, of eight feet internal diameter, it will be convenient to use an air current
through the kiln or oven of about 1200 cubic feet per minute, this air may con-

page_text: veniently be at a temperature of 800° Fahrenheit, and the operation of baking or
drying will occupy 20 hours or thereabouts, but when the kiln is in regular work I
draw material from the bottom of the kiln in regular quantities and at regular
intervals and I vary these slightly until the material comes out "cooked" exactly
as I desire it. The heated air enters the kiln or oven by the pipes f, f, which are
in connection with the upper part of the casing of the regulating apparatus.
The hot air from the stove enters the lower part of this casing at h and passing up
within the casing it expands the brass rod i more or less, according to its
temperature.
k is a lever resting on the rod i and moved by it as it elongates and contracts; Z
is a valve connected with the lever k, when it is lifted it admits to the casing g cold
air coming direct from the blowing engine to mingle in greater or less quantity
with the air which has passed through the stove, and so to make a mixture of about
the standard temperature to which the regulator is adjusted.
The lever also transmits motion to the index m which by its movement indicates
fluctuations of temperature within the casing g.
The kiln can be made square or rectangular, in which case the louvre plates are
made of the same design, but straight instead of circular, and the plaster is drawn
out at one or two sides.
Having thus described the nature of my said Invention, and the manner of per-
forming the same, I would have it understood that I claim,-
First. The baking or drying of gypsum contained in a suitable kiln or oven by
passing amongst it heated air at a carefully regulated temperature, substantially as
herein described.
Second. The kiln or oven and parts in connection therewith so arranged that
the material charged in at the top descends to the bottom where it is withdrawn,
and whilst descending is turned about and caused to be permeated by heated air,
substantially as herein described.
Third. The kiln or oven and parts in connection therewith so arranged that the
material charged in at the top descends to the bottom, where it is withdrawn, and
whilst descending is caused to be permeated by heated air, the temperature of which
is automatically regulated, substantially as herein described.
In witness whereof, I, the said Robert Thompson, have hereunto set my hand
and seal, this Fourteenth day of June, in the year of our Lord One thousand
eight hundred and seventy nine.
R. THOMPSON. (L.S.)