IMPROVEMENTS IN APPARATUS FOR EMPLOYING HEATED AIR IN DRYING OR BAKING VEGETABLE OR OTHER SUBSTANCES
Year: 1884

page_text: I SAMUEL CLELAND DAVIDSON of Belfast in the County of Antrim, Ireland,
Merchant do hereby declare the nature of my invention for IMPROVEMENTS IN
APPARATUS FOR EMPLOYING HEATED AIR IN DRYING OR BAKING VEGETABLE OR
OTHER SUBSTANCES to be as follows: —
In the apparatus for employing heated air in drying or baking described in the
Specification of former Letters Patent granted to me and dated 16th April 1879
No 1480, the trays or sieves are placed one above another in a single column within
an upright chamber, at the bottom of which is a self-emptying hopper consisting of
sloping shelves or shoots so arranged that while they guide into a receiving tray
any material falling upon thom they have open spaces between them through which
the heated air can ascend to the material on the trays above. To draw the requisite
quantity of hot air up through the trays when so placed (i.e. four trays one above
the other in single column) a considerable draft power is necessary and to produce
this a high air chimney has been employed in which the draft is accelerated by the
injection into its base of the smoke from the furnace chimney. I now construct
this drying chamber so that the necessity for the high air chimney is obviated.
The improved apparatus consists practically of 2 parts, namely an upright chamber
in which the self emptying hopper is placed and a horizontal flue or duct leading
from the top of same and having the sides, ends and bottom close, but the top
open,
Over the open top, the trays or sieves, with the material to be dried spread upon
them, are so placed that they form the cover or top side of the horizontal flue.
They are carried on ledges or guides attached to the sides of the flue or duct and
when being worked are pushed along one before the other from end to end of it.
I preferably construct this flue to carry two rows of trays one above the other and
make its length equal to four times its width. The top row of trays is level with
the top edge of the flue and the second row is a little below the top row so that
there is thus a space left between the two rows of trays and a deeper space below
the lower row.
The lower space I preferably make equal to two thirds of the depth of the hori
zontal flue leaving one third in the top part to be occupied by the trays and upper
space

page_text: The hot air after ascending through the upright chamber which contains the self
emptying hopper diffuses itself along the horizontal flue below the trays and being
under a natural pressure upwards from the stove and there being a much larger
primary tray surface for it to spread over than in the apparatus described in my
said previous Specification, the full volume of the hot air ascending from the stove
is able to find its way up through the material on the trays easily and without the
assistance of any air chimney such as referred to in my said previous Specification
and the material on the trays becomes very evenly and satisfactorily dried. The
self emptying hopper in the upright chamber may be constructed exactly in the
same way as described in my said previous Specification, or it may be arranged so
as to project the material falling upon it outside the chamber into receptacles or
receiving troughs.
The sides of the upright chamber are double sheeted with an air space between
the sheets, and cold air from outside is admitted to the base of the air space through
openings provided for the purpose and it escapes heated from the top of same
into the horizontal drying flue.
This air current keeps the outside of the casing cool and at the same time utilizes
the heat which it picks up from the casing by producing more hot air for drying
purposes. The trays or sieves for carrying the material to be dried, are of similar
construction to those described in my said previous specification. This arrange-
ment of drying chamber can be set ou top of an air heating stove and the heated
air from same employed in it; or heated air from any other suitable source may
be led into it by any convenient arrangement of flue or pipe. The horizontal fluo
may be made single, or several may be side by side, and the rows of trays one
above the other may be single or multiple to suit circumstances.

page_text: I SAMUEL CLELAND DAVIDSON, of Belfast in the County of Antrim, Ireland,
Merchant do hereby declare the nature of my invention for "IMPROVEMENTS IN
APPARATUS FOR EMPLOYING HEATED AIR IN DRYING OR BAKING VÉGETABLE OR
OTHER SUBSTANCES, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :—
In the apparatus for employing heated air in drying or baking described in the
Specification of former Letters Patent granted to me and dated 16th April 1879,
No 1480 the trays or sieves are placed one above another in a single column within
an upright chamber at the bottom of which is a self-emptying hopper consisting of
sloping shelves or shoots so arranged that while they guide into a receiving tray
any material falling upon them, they have open spaces between them through which
the heated air can ascend to the material on the trays above. To draw the requisite
quantity of hot air up through the trays when so placed (i.e. four trays one above
the other in single column) a considerable draft power is necessary and to produce
this a high air chimney has been employed in which the draft is accelerated by the
injection into its base of the smoke from the furnace chimney. I now construct
this drying chamber so that the necessity for the high air chimney is obviated.
The improved apparatus consists practically of two parts viz:-a vertical air duct
in which the self-emptying hopper, referred to in the before mentioned Specification,
or a modified form of same is placed, and a horizontal air flue leading from the top
of same and in which trays, sieves or other suitable carriers for the material to be
dried are placed,
The sides of the upright air duct are double sheeted with an air space between
the sheets and cold air from outside is admitted to the base of the air space through
openings provided for the purpose and it escapes heated from the top of same into
the horizontal drying flue.
This air current keeps the outside of the casing cool and at the same time
utilizes the heat which it picks up from the casing by producing more hot air for
drying purposes.
The self-emptying hopper in the vertical air duct may be constructed exactly in
the same way as described in the said previous Specification but I prefer to arrange
it so as to project the material falling upon it outside the chamber into receptacles
or receiving troughs. This arrangement is plainly shewn in the drawings.
The horizontal air flue may be constructed in either of the following ways:
1st With the sides, ends and bottom closed and the top open, and over the open top
the trays or sieves with the material to be dried spread upon them are bo placed
that they form the cover or top side. They are carried on ledges or guides attached
to the sides of this air duct and when being worked are pushed along, one before
the other, from end to end of it. This air duct is preferably constructed to carry
2 rows of trays, one above the other, and its length is made equal to 4, 5 or 6 times
its width. The top row of trays is level with the top edge of the flue and the
2nd row is a little below the top row so that there is thus a space left between the
2 rows of trays and a deeper space below the lower row.
The lower space is pre-
ferably made equal to 2/3rds of the depth of the horizontal flue leaving 1/3rd in the
top part to be occupied by the trays and the space between the trays.

page_text: The hot air after ascending through the upright air duct which contains the self-
emptying hopper diffuses itself along the horizontal air duct below the trays, and
being under a natural pressure upwards from the stove and there being a much
larger primary tray surface for it to spread over than in the apparatus described in
the said previous Specification, the full volume of the hot air ascending from the
stove is able to find its way up through the material on the trays easily and without
the assistance of any air chimney such as is referred to in the said previous Specifi-
cation and the material on the trays becomes very evenly and satisfactorily dried.
Or, 2udly The horizontal air flue may be closed or covered in over top and an
opening left in the cover (with or without a short air chimney) for exit of the moist
air at the end furthest from the vertical air duct, a space being left between the
cover and top tier of trays about equal to the space between the tiers of trays
themselves. With this arrangement of air flue the ledges or rails carrying the tiers
of trays may with advantage be on an incline plane the higher end of the incline
plane being over the vertical air duct.
Figures 1 and 2 of the annexed drawings illustrate my invention. A is the
upright air duct; B, B the arrangement of sloping shoots forming the self-emptying
hopper therein. O is the horizontal air duct leading from the top of the upright
air duct A, the sides, ends and bottom of this horizontal air duct being closed and
the top (in this modification) open. D and D'are respectively the lower and upper
ledges or guides for 2 rows of trays, these ledges or guides being in this modifica-
tion borizontal, E, E are receptacles or receiving troughs for the material which
falls from the self-emptying hopper B, B. Tho upright air duct A is double sheeted,
as shown, so as to form an air space and passage as already described.
Instead of the vertical air-duct A being situated at one end of the horizontal air
duct O, as shown in the drawings, it may be at or near the middle thereof in which
case the horizontal air duct C should have a partition to divide the heated air and
cause it to travel towards both ends of the horizontal duct.
The trays or aieves for carrying the material to be dried are of similar construc-
tion to those described in my said previous Specification.
My improved apparatus for employing heated air in drying or baking can be set
on top of au air heating stove and the licated air from the same employed in it, or
heated air from any other suitable source may bo led into it by any convenient
arrangement of flue or pipe. The horizontal air duct may be made single or several
may be sido by side and the rows of trays one above the other may be single or
multiple to suit circumstances,
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
J
1. Constructing apparatus for employing heated air in drying or baking with
a vertical air duct fitted inside with aloping shelves or shoots arranged louvre-like
to form a self-emptying hopper and on the top of said air duct a horizontal fluo
fitted with trays or other suitablo carriers for tho material to be dried, all substan-
tially as herein before described.
2. The combination of parts forming an improved apparatus for employing
heated air in drying or baking as herein before described and represented in the
drawings,