A Special Heating Apparatus with Regulated Draught for Drying Gypsum and Certain other Products at a Regulated Temperature.
Year: 1898

page_text: Date of Application, 1st Mar., 1898
Complete Specification Left, 31st Dec., 1893-Accepted, 1st June, 1899
PROVISIONAL SPECIFICATION.
A Special Heating Apparatus with Regulated Draught for Drying
Gypsum and Certain other Products at a Regulated Temperature.
HENRY KELWAY BAMBER, F.I.C., Analytical & Consulting Chemist, Westminster
Chambers, 9, Victoria Street, S.W., I do hereby declare the nature of this invention
to be as follows:
-
A double cased oven opening at one or both ends, between the casing of which
a high boiling petroleum or other suitable substance is placed to regulate &
equalise the temperature of the internal space. Through the latter air is passed
by means of an inlet pipe which first passes through the fire used to heat the oven,
or otherwise. At the opposite end there is placed an exit pipe, connected with a
long pipe or chimney to accelerate the draught. Into the interior space the
material to be dried or heated is placed, being previously packed in a case on small
wheels, for convenience of running it into & out of the oven. In the inlet or outlet
pipe there is a simple tap, valve, or damper for increasing or lessening the draught
as desired.
Dated this First day of March 1898.
A Special Heating Apparatus with Regulated Draught for Drying
Gypsum and Certain other Products at a Regulated Temperature.
I, HENRY KELWAY BAMBER, of 9, Victoria Street, London, S.W., Analytical
and Consulting Chemist, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer
tained in and by the following statement:-
-
This invention relates to a new and improved apparatus for preparing plaster of
Paris from the original gypsum or plaster stone and from previously used plaster
of Paris.
If gypsum is subjected to a fairly constant and uniform temperature of about
300° or 350° Fahr. in an enclosed oven or the like and a current of hot air is
allowed to enter the oven, circulate through the gypsum and escape through a
suitable outlet, this current of air carries with it the steam liberated from the
gypsum, and the conversion of gypsum or plaster stone into plaster of Paris proper
is more conveniently and expeditiously effected than by any method in use at the
present time and without fear of calcining the gypsum and rendering it or any
portion of it unfit for the purpose intended.

page_text: The limits of temperature above mentioned are those within which most samples
of gypsum are best treated but the temperature may be required to be varied with
particular samples, a single trial being sufficient to determine the best temperature.
I employ an oven of cylindrical or other suitable shape having a door at one
end. Enclosing the oven on all sides except the back and front is an outer shell
or casing. Between the oven and the outer shell a space is left which is filled with
a heavy grade petroleum oil or other suitable fluid having a high boiling point
preferably about 500° or 600° Fahr.
The function of the oil is to aid in maintaining the oven at a uniform and
constant high temperature.
The top of the outer shell is provided with an aperture for the purpose of supply-
ing or renewing the oil, and of testing its temperature.
Underneath the oven is fitted a fire grate of suitable dimensions having an
ordinary flue at one end and at the other end a grate door which should be
situated immediately underneath the oven door.
Over the fire and close to the outer shell of the oven is a pipe made of iron or
other refractory material, one end of this pipe passes through the back of the grate
and forms an inlet for the air, the other end passes through the front of the grate
, above the grate door. In the oven door immediately above, a hole is bored and a
circular flange situated outside for connection with the grate pipe. This con-
nection is secured by means of a second curved pipe with two butt joints or by any
other convenient means.
At the back end and at the top of the oven an outlet pipe is provided, which
may lead into the flue in order that the draught may be increased, and condensa-
tion of escaping steam and the possible return of moisture into the oven avoided.
In the accompanying drawings which illustrate this my invention, Figure 1 is
a sectional side elevation of my said invention. Figure 2 is a front and Figure 3
a back elevation of the oven, and its outer shell.
A, is the enclosed oven, B, the door of the same, and L, the outlet pipe. C.is
the outer shell or casing the space D containing the petroleum or other fluid,
E being the aperture for supplying and receiving the oil and testing its tempera-
ture. M indicates the position of the fire grate, F being the hot air pipe over
same, having at one end the air inlet G, and terminating at the other end with
an adapter or butt joint K, H, for junction with the connecting pipe J.
The other end of the said pipe connects with the oven by means of a butt joint
at "I" as shown.
Inside the oven door I may fit a deflector plate perforated or otherwise for dis-
tributing the hot air as desired.
I do not limit myself to one hot air pipe, two or more might be employed, with
'slight modifications of the apparatus.
Neither do I limit myself to an induced current of air though I employ it in
preference to others, obviously the same results might be obtained by forced
draught, employing any well known mechanical methods.
cases I
The gypsum or plaster stone or previously used plaster of Paris to be converted,
is broken up into suitable sized lumps before being inserted in the oven, (in some
may use a series of latticed or perforated open wagons for containing the
gypsum running on tramways or the like within the oven). The door is then
shut, the pipe in the grate connected with the oven as previously described, and
the fire lit.
An induced current of air is at once set up in the pipe system, entering the
pipe at its air inlet, it is heated in its passage over the fire, passes into the oven,
and finally escapes by the outlet carrying with it the steam from the heated gypsum.
The cessation of steam through the outlet, indicates that the conversion is
completed.
The draught can if desired be regulated by means of a perforated cap attached
to the free air inlet similar to the ventilators employed in the ordinary cooking
ovens.

page_text: 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. An apparatus for preparing plaster of Paris from original gypsum or plaster
stone, or from previously used plaster of Paris, consisting of an oven the interior
of which can be kept within certain limits of temperature in the manner described,
through which a current of hot air is caused to circulate.
2. An apparatus for preparing plaster of Paris from original gypsum or plaster
stone, or from previously used plaster of Paris, consisting of an oven provided
with double walls so as to contain petroleum or other fluid possessing a high
boiling point through which oven hot air is caused to circulate.
Dated this 31st day of December 1898.
LEWIS W. TAYLOR,
109, New Oxford Street, London, W.C., Applicant's Agent.