IMPROVE- MENTS IN APPARATUS FOR DESICCATING OR DRYING AIR
Year: 1885

page_text: I JOHN DICK of 218 Saracen Street Possil Park, Glasgow, in the County of
Lanark Engineer, do hereby declare the nature of the said invention for "IMPROVE-
MENTS IN APPARATUS FOR DESICCATING OR DRYING AIR to be as follows:-
This Invention has for its object improvements in apparatus for desiccating or
drying air and whilst generally applicable for purposes in which dried air is
necessary or employed the Invention is especially applicable and intended to be
used in connection with apparatus for withering or drying the green leaf of the tea
plant in the process of manufacture.
The apparatus constituting the Invention consists of a stove preferably rectangular
in plan and constructed of metal plates or partly of metal plates and partly of fire
brick the furnace or fire box being in a central position. On two sides of the fire
box air chambers are arranged and through them the flames and other products of
combustion pass, the draught being controlled by dampers. Inside the air chambers
a series of hollow metal or fire brick plates or blocks preferably rectangular in form
are so placed as to give a large heating surface and besides being hollow throughout
their lengths the said plates or blocks have a series of transverse passages or openings
arranged zig-zag and alternated with hollow bosses or fitting parts so that when a
number of plates or blocks are placed together the corresponding bosses on each of
them meet and form a honeycomb or cellular pile through which the products of
combustion pass in all directions so presenting to the air a large heat radiating
surface of a labyrinthine or tortuous character whilst at the same time the air is
prevented from coming in contact with the gases.
The air passages are preferably vertical and the admission is controlled by
shutters doors or valves at the lower part of the stove similar shutters, doors, or
valves being also placed at the upper part of the stove to regulate and prevent the
admission of air into the desiccating chambers as required.
The desiccating chambers (of which two or more (corresponding to the number
of air heating chambers in the stove may be employed and which are preferably
placed above the air heating chambers and correspond with the contour of the
stove) have their sides and top formed of asbestos cloth or other like or suitable
material fixed to metal wood or other frames. The fabric or material, of which
one, two, or more thicknesses may be used, is treated with an absorbent of moisture,

page_text: Calcium Chloride or any of the other well known absorbents, (having regard to the
purpose for which the desiccator is to be employed) being used the same not
constituting any part of this Invention.
From one side of each desiccating chamber a pipe or duct leads to an exhaust
fan or apparatus and in working, the fan draws in atmospheric air through the
sides and top of the chamber thus depriving the air of moisture in its passage
through the absorbent.
When it becomes necessary to dry or evaporate the moisture out of the absorbent
in one air desiccating chamber the damper between the stove and the corresponding
air heating chamber is drawn so as to admit the flame and other products of com-
bustion from the stove into the said air heating chamber and simultaneously or
afterwards the shutters, doors, or valves, closing the upper and lower ends of the
air passages through the said chamber, are opened the door at the top also serving
to shut off communication between the exhaust fan or apparatus and the desiccating
chamber.
By this means currents of air are caused to pass through the heating chamber
and thence into the desiccating chamber and the fabric or material of which its
sides and top are composed being permeable the heated air passes through,
evaporating and carrying with it the moisture which had been absorbed during
the previous inward passage of air.
Whilst this is taking place the exhaust fan is drawing air through the other or
another desiccating chamber and when it requires regenerating a similar drying is
caused the desiccating chambers thus working alternately.
The movement of a lever fixed on a spindle carrying intermediate mechanism of
_any suitable description accomplishes the simultaneous opposite movements of the
doors and dampers to change whichever chamber may be undergoing regeneration
into readiness for desiccating the air and vice versa.

page_text: Improvements in Apparatus for Desiccating or Drying Air.
I, JOHN DICK of 218 Saracen Street Possil Park Glasgow, in the County of
Lanark, Engincer, 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 has for its object improvements in apparatus for desiccating or
drying air and whilst generally applicable for purposes in which dried air is
necessary or employed the invention is especially applicable and intended to be
used in connection with apparatus for withering or drying the green leaf of the
tea plant in the process of manufacture.
As shown in back end elevation at figure 1; in longitudinal vertical section at
figure 2; in front end elevation at figure 3; and in part plan and part horizontal
section at figure 4, of the appended drawings the apparatus constituting the
invention consists of a chamber preferably rectangular in plan and constructed of
metal plates or partly of metal plates and partly of fire brick. The chamber is
divided into three compartments the central one A, of which constitutes a furnace
or fire box whereof the fire grate or bars may be above, at, or below the ground
level. The furnace is subdivided into fuel and smoke chambers by a plate or
wall a, the said plate or wall or a continuation. of it extending longitudinally to
the points b, fig. 4, and vertically from top to bottom of the casing. The furnace A,
opens into two chambers B, one on each side of it the openings or flues being
furnished with doors or dampers C, hung from chains passing over pulleys D,
centred on a bridge E, the doors or dampers being counterpoised by weights F, as
indicated. Within each side chamber B, a series of metal or fire clay plates or
blocks are placed as seen at fig. 2, the said plates or blocks entirely filling the space
between the top and bottom of the chamber.
Fig. 5, is a side elevation and fig. 6, a transverse section on the line x, x, fig. 5,
of one of the blocks drawn to a larger scale, and as more particularly seen by these
figures each of these plates or blocks is hollow vertically the hollow part being
divided into two distinct channels or passages c, d. One half of each passage c, is
forined in one plate and the other half in the neighbouring plate and besides the
vertical channels or passages, channels or passages e, run horizontally through the
blocks from one vertical channel c, to another, these holes or passages e, being
arranged as shewn at fig. 5, where each of the smaller circles indicates one such
passage. The channels d, are partly constituted by hollow bosses so formed that
when a number of the plates or blocks are placed together the corresponding bosses
on each of the plates meet or nearly meet. It will thus be seen that each
passage d, is of a tortuous or labyrinthine formation, for example the passage
beginning at 1, figs. 2 and 6, passes around both sides of the lowest horizontal
passage e, into the space 2, thence around both sides of the next higher passage e,
into the space 3, and so on till the upper part of the chamber is reached. These
vertical tortuous passages d, are air passages into which the air enters at the lower
end through the chamber G, and escapes at the upper end into the part I, of the
stove. The chamber G, is provided with a door H for closing it when desired.

page_text: The passages c, e, are passages for the gases and products of combustion from the
stove A, these being caused to pass through them by opening one and closing
the other damper C. It being so conducted through the blocks on one side of the
dividing plate a, the heat passes in the direction of the arrow fig. 4, into the
chamber J, thence in the opposite direction through the blocks on the other side of
the dividing plate a, to the chimney or flue K, which, to promote a better draught
is through a portion of its height divided into two parts by the wall or division
plate shown in dotted lines at L, figs. 2, 3 and 4. The hollow blocks at their lower
ends rest upon stools y, running the length of the chamber G, the spaces between
these stools being open to the passages d, but closed to the passages c, and in
putting the blocks together, to prevent the passage of the gaseous products of com-
bustion into the chamber I, the meeting edges are rabetted or checked a plate
being inserted into the check as indicated at w figs. 5 and 6 and luted with
asbestos putty or equivalent heat resisting material. Similar material is or may
also be used at the junction of the lower parts of the blocks to there prevent the
escape of the gaseous products. The arrangement and construction above described
besides giving a long or tortuous passage to the air to be heated and preventing
any admixture with it of the products of combustion also presents a very large
heating surface. The part I, of each air heating chamber is connected by a pipe M,
with the lower part of a chamber N, preferably rectangular in form and carried
upon pillars or columns O, and with each of the said chambers N, a vertical
branch P, leading into a duct or main Q, also communicates. At the parts opening
into the chamber N, each pipe M, is furnished with a valve R, and each pipe P,
with a valve R', which valves are so set and connected by levers and cranks f, or
equivalent mechanism relatively with each other that when one valve is open the
other is closed.
The duct or main Q, communicates with an exhaust fan and each of the
chambers N¹ is cut off when required from such communication by operating the
valve S, so as to close the pipe.
The chambers N, have their sides and tops formed of asbestos cloth, or other
fabric stretched upon metal wood or other frames and the said fabric of which two
or more thicknesses may be employed is treated with an absorbent of moisture,
Calcium Chloride, Caustic Lime or any of the other well known absorbents, having
regard to the purpose for which the apparatus is to be employed, being used, the
same not constituting any part of this invention. The chambers N, so constructed
and prepared constitute desiccating chambers for air drawn in through the sides
and tops of them by the action of the fan before referred to, the air being deprived
of its moisture in passing through the absorbent and thereafter drawn off through
the pipe P, for employment as required.
When it becomes necessary to dry or evaporate the moisture in one of the air
desiccating chambers N, communication between that chamber and the exhaust
fan is cut off by closing the valves R, and S. At the same time the valve R, in
the pipe M, is opened thereby effecting communication between the chamber I,
into which the heated air is discharged as before set forth, and the interior of the
desiccating chamber N. By this means currents of heated air are caused to pass
into the interior of the chamber and thence through the permeable fabric or
material of which its sides and top are composed into the atmosphere, the heated
air in so passing evaporating and carrying with it the moisture which had been
absorbed during the previous inward passage of air.
The desiccating chambers N, work alternately, that is to say, whilst one chamber
is being regenerated as above described, the exhaust fan is drawing air through the
other, the stove or air heating chamber in communication with that other being
during such time thrown out of operation by closing the damper C, in the flue or
passage communicating between it and the furnace A.
When it is desired to heat the air after being dried the door or valve H, of the
chamber G, is closed as is also the valve R', in the pipe P, and the valves R and S,
being opened the action of the fan draws the air first through the desiccating

page_text: chamber N, thence through the air heating chamber B, and downwards into the
pipe W, the desiccating chambers and stoves being in this case also worked
alternately.
Although I have described and shown on the drawings the apparatus as consisting
of two desiccating chambers and relative air heating stoves it is to be understood
that I do not confine myself to this number as manifestly one or a larger number
of desiccators and stoves may be employed.
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
ހ
First. The general arrangement and combination of parts constituting the
apparatus for desiccating or drying air herein-before described with reference to
the drawings annexed.
Second. In apparatus for desiccating or drying air a stove consisting of a
furnace or fire grate and a chamber or chambers cominunicating there with and
having at the interior thereof a series of hollow blocks so constructed as to
present a tortuous or labyrinthine passage both to the air to be heated and the
gaseous products of combustion substantially as described with reference to the
appended drawings.
Third. The hollow blocks hereinbefore described and their employment as and
for the purpose set forth.