Improvements in Apparatus for Employing Heated Air in Drying or Baking Vegetable or other Substances.
Year: 1887

page_text: PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Employing Heated Air in Drying
or Baking Vegetable or other Substances.
I SAMUEL CLELAND DAVIDSON, of Sirocco Works, Belfast, in the County of Antrim,
Ireland, Merchant, do hereby declare the nature of this invention to be as follows:-
:-
My invention has reference to apparatus of that description in which the material to
be dried or baked is exposed upon superimposed trays, sieves or other suitable carriers
arranged in a drying chamber to the action of heated air which passes up through the
carriers and the material thereon. In constructing and working apparatus of this
kind it has been usual to arrange that all the heated air shall pass up first through the
lowest carrier of each superimposed sei and the material thereon and then successively
through the other carriers of the set and the material thereon; when the material on
the lowest carrier has been sufficiently dried or baked this carrier has been withdrawn,
all the other carriers in the apparatus have then been shifted one step down and
another carrier containing fresh material has been introduced at the top. It has been
found however that the heated air sometimes becomes much saturated with vapor in
passing through the material on the lower carriers and that it consequently has a
steaming or stewing effect on the material on the upper trays which is deleterious in
the case of many substances but particularly of tea which rapidly deteriorates in
quality if subjected to a steaming heat. Further the material on the lowest tray
occasionally gets overfired or burnt.
Now my invention consists of a special construction of apparatus in which a portion
of the heated air is led at its initial temperature from under the lowest of the super-
imposed carriers direct to the upper ones which it thus reaches without having passed
through any material on the lower ones. The material on the upper carriers thus
receives a sharper drying heat than if all the air reaching them had passed up through
the material on the lower carriers, and further the distribution of the fresh heated air
to the superimposed carriers effects a more equal rate of drying on each of them
simultaneously.

page_text: The manner in which my invention may be carried into effect is as follows:-
Mounted upon or connected with a stove or other apparatus for heating air is a
drying chamber into which the air heated by such apparatus passes. In the upper
part of this chamber are arranged one, two, three or more sets of superimposed
carriers; each set is composed of, say, five carriers more or less which are free to be
moved in and out like drawers. Between the sets and between each end set and the
corresponding end of the drying chamber are spaces, open at bottom and closed at
the top and sides, except that there are side perforations or openings giving access to
the underside of the two or three uppermost carriers. With this construction a portion
only of the fresh heated air will pass up through the lower carriers and the material
thereon and then through the upper carriers while the remainder of the heated air will
enter the spaces above described and finding its way through the side perforations
will distribute itself beneath the upper carriers and pass through them and through
the material thereon without having previously taken up any vapor or moisture by
passing through the material on the lower carriers. Therefore as has already been
stated the material on the upper carriers will receive a sharper drying heat, and the
distribution of the fresh heated air to the superimposed carriers will effect a more
equal rate of drying on each of them simultaneously.
The 50th
100
J. C. MEWBURN,
169, Fleet Street, London,
Agent.

page_text: Improvements in Apparatus for Employing Heated Air in Drying
or Baking Vegetable or other Substances.
I, SAMUEL CLELAND DAVIDSON of Sirocco Works, Belfast in the County of Antrim,
Ireland, Merchant, 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 has reference to apparatus of that description in which the material to
be dried or baked is exposed upon superimposed trays, sieves or other suitable carriers
arranged in a drying chamber to the action of heated air which passes up through the
carriers and the material thereon. In constructing and working apparatus of this kind
it has been usual to arrange that all the heated air shall pass up first through the
lowest carrier of each superimposed set and the material thereon and then successively
through the other carriers of the set and the material thereon; when the material on
the lowest carrier has been sufficiently dried or baked this carrier has been withdrawn,
all the other carriers in the apparatus have then been shifted one step down and
another carrier containing fresh material has been introduced at the top. It has been
found however that the heated air sometimes becomes much saturated with vapour in
passing through the material on the lower carriers and that it consequently has a
steaming or stewing effect on the material on the upper trays which is deleterious in
the case of many substances but particularly of tea which rapidly deteriorates in quality
if subjected to a steaming heat. Further the material on the lowest tray occasionally
gets overfired or burnt.
Now my invention consists of a special construction of apparatus in which a portion
of the heated air is led at its initial temperature from under the lowest of the super-
imposed carriers direct to the upper ones which it thus reaches without having passed
through any material on the lower ones. The material on the upper carriers thus
receives a sharper drying heat than if all the air reaching them had passed up through
the material on the lower carriers, and further the distribution of the fresh heated air
to the superimposed carriers effects a more equal rate of drying on each of them
simultaneously.
The manner in which my invention may be carried into effect is as follows:-
Mounted upon or connected with a stove or other apparatus for heating air is a
drying chamber into which the air heated by such apparatus passes. In the upper
part of this chamber are arranged one, two, three or more sets of the superimposed
carriers ; each set is composed of say 4 carriers more or less which are free to be
moved in and out like drawers. Between the sets and between each end set and the
corresponding end of the drying chamber are spaces or side chambers, open at
bottom, and closed at the top and sides except that there are side openings or per-
forations giving access to the underside of the upper carriers. With this construction
a portion only of the fresh heated air will pass up through the lowest carriers and the
material thereon and then through the upper carriers while the remainder of the heated

page_text: air will enter the spaces or side chambers above described and be drawn in through
the side openings beneath the upper carriers. As the volume of air decreases by
cooling in passing up through each layer of material on the carriers the fresh heated
air from the side chambers at the initial temperature of the heated air supply mixes
with this cooler and diminished volume between the carriers thereby raising its
temperature and renewing its drying capacity. Wherefore, as has already been stated
the material on the upper carriers receives a sharper drying heat, and the distribution
of the fresh hot air to the superimposed carriers effects a more equal rate of drying on
each of them simultaneously.
Figures 1 and 2 of the annexed drawings represent an apparatus constructed as
above described. F represents the heated air supply flue or chamber. G G are the
side air chambers for carrying a direct supply of fresh heated air from the chamber F
to each of the carriers. H H are the openings in the side air chambers G G for
entrance of the heated air from the supply chamber F. J J are the openings in the
side chambers G G for letting the beated air pass direct to the underside of each
of the upper carriers. KK are the superimposed carriers. L is a perforated
cover over the top of the drying chamber.
Figures 3 and 4 represent a form of the apparatus in which the carriers K K are
arranged in superimposed rows and are passed one in front of another on suitable slides
through from end to end of the drying chamber. The same letters of reference as
those in Figures 1 and 2 indicate corresponding parts. Figures 5 and 6 represent
another form in which the carriers consist of superimposed endless webs or bands.
These endless webs may be composed of a series of light transverse battens or straps
of perforated iron connected together by links or be otherwise suitably formed. They
are mounted on rollers M M caused to rotate by gearing N N driven by the
handle O.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the sane is to be performed, I declare that what I
claim is
In an apparatus of the kind or description herein referred to for employing heated
air in drying or baking vegetable or other substances, the construction of the drying
chamber with side chambers or side passages as hereinbefore described whereby a
portion of fresh heated air at its initial temperature is conveyed direct to the underside
of each or any of the upper superimposed carriers which it thus reaches without
having passed through any of the material on those below, as set forth.
Dated this 20th day of July 1888.
J. C. MEWBURN,
169, Fleet Street, London,
Agent.