Improvements in Air Heating Stoves, more especially intended for use with Machinery or Apparatus for Drying Tea.
Year: 1893

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Date of Application, 6th Feb., 1893-Accepted, 27th May, 1893
COMPLETE SPECIFICATION.
Improvements in Air Heating Stoves, more especially intended for
use with Machinery or Apparatus for Drying Tea.
I, WILLIAM JACKSON, of Thorn Grove, Mannofield, Aberdeen, Scotland,
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 :-
My invention relates to air heating stoves wherein tubes are used for heating
air and is intended more especially for use in stoves used for heating air for use in
a tea drying machine or apparatus and I will describe it in that connection. The
object of my invention is to provide means whereby the tubes are so locked or
secured in the tube plate at the exit end that smoke or fumes from the furnace are
prevented from being drawn into the place where the hot air is to be used for
instance into a tea drying chamber.
In stoves as hitherto made the tubes have been inserted from the tube plate at
the inner end (ie. the end next the drying chamber) and they have been connected
to it before the drying chamber or the like could be placed in position.
This has been found defective in practice as when a tube, or tubes, or spirals
within the tubes, has or have had to be withdrawn it has been necessary to move
the drying machine or the like.
In an arrangement according to my invention the tubes can be inserted through
the outer tube plate, or that at which the air enters, and be locked and firmly
secured or connected to the other or inner tube plate next the drying chamber, or
the like, so that any tube, or tubes, or the spirals within them, can be inserted, or
withdrawn, at any time without disturbing the drying chamber, or the like, and
this is of great importance as it is found that nuts and screws arranged in the
ordinary way when exposed to dry heat for a time in a drying machine or the like
get so stiff that they cannot be unscrewed and have to be cut and broken to permit
of the machine or the like being taken to pieces to allow tubes to be inserted in
stoves as hitherto made.
In the accompanying drawings
Figure 1 is an elevation partly in section and Figure 2 is an end view of a
multi-tubular air heating stove having the tubes applied thereto according to my
invention.
I have shewn at B a tea drying apparatus connected with the said stove although
of course this may be replaced by any other apparatus in which the heated air is
to be used. A is the stove it being heated by a furnace or furnaces a; a² is the
chimney. The products of combustion from the furnace or furnaces passing
around the tubes on their way to the chimney which will be the most convenient
way in practice. c is the inner tube plate next drying chamber and d is the
outer tube plate. E E are the tubes in the stove and e e represent spirals one
being shewn partially withdrawn from a tube.
Figures 3 and 4 are side views of one of the tubes the views being at right
angles to each other. Figure 5 is an end view.
Figure 6 shews a portion of each tube plate with one of the tubes in place and
Figure 7 is a section thereof.
Figure 8 is an end view of Figure 6 and
Figure 9 is an inside view of part of the tube plate c shewing the formation of
the locking holes in the said tube plate.
At the inner end of each tube are projections or keys e² cast or otherwise
formed on or attached to the opposite sides of the exterior of the tube at, or near,
[Price 8d.1

page_text: its end; I have shewn two such projections but I may use one or more such
projections.
In the tube plate c are keyways or passages c² for each of the projections e² to
pass through, the said keyways opening into inclined and partly circular or helical
recesses at c. When the projections e² are inserted into the passages c³ the tube
is turned which may be effected by a spanner or tool applied to the squared or
angled end at e and the projections e moved round in the helical recesses c³, and so
the end of the tube is forced against the rim c* surrounding the opening in the
tube plate as shewn in Figure 7. Each tube is introduced into the stove through
the openings for it in the tube plate_d_and_the end is secured to the tube plate cas
aforesaid and then after asbestos fibre or other suitable packing material has been
put in the space a cap d² is slipped over the squared or angled end of the tube
which cap 2 may have an opening d³ in it smaller than the passage in the tube to
reduce the area of the cold air inlet to the tube. Packing material may also be
inserted in the space y or between the end of the tube and the rim c¹ or both.
The chimney a² may be in any suitable position. When it is in the position
shewn its lower length can be removed to withdraw the tubes and spirals
immediately behind it.
In place of projections e² and the recesses c³ ³ therefor, as shewn, the junction
may be effected by screws or worms engaging in an analogous manner.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In a multitubular air-heating stove the means described allowing of the tubes
being inserted through the outer tube plate and being locked or firmly secured
to the inner tube plate substantially as and for the purposes hereinbefore
explained.
2. In a multitubular air-heating stove, tubes having at one end projections e²
or their equivalents engaging with recesses c² 3 or their equivalents in the tube
plate and at the other end provided with packing as at a and covering caps d² all
substantially as hereinbefore described.
abruare 1002
J. H. JOHNSON & Co.,
Agents.