Apparatus for Drying.
Year: 1898

page_text: Date of Application, 18th June, 1898-Accepted, 20th Aug., 1898
Apparatus for Drying.
I, SAMUEL SIDNEY BROMHEAD, of 171, Queen Victoria Street, County and City
of London, Patent Agent (communication from abroad), 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:-
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This invention relates to drying apparatus in which the materials are dried
through contact with highly heated steam, the outside or atmospheric air being
completely excluded. The steam to be heated and used in the drying operation
is that which is produced from the material to be dried.
The latent heat of the evaporating steam must be precipitated into heating cham-
bers which are separated from the drum, from which chambers it is later obtained.
The drying apparatus, which is the object of this Patent Application, consists
of a space completely shut off from the action of atmospheric air, and open to a
current of steam heated above the boiling temperature of water. This steam
is obtained from the moisture in the material to be dried, and by contact with
said material causes same to evaporate further moisture.
The steam can be drawn off from the drying chamber by any suitable outlet,
fitted in any suitable part thereof, to a second enclosed space independent from
the main chamber, where it is condensed.
This arrangement has this great advantage over the drying apparatus now
used, in which the latent heat of the steam is applied to drying purposes, that
the steam which is drawn off from the drying chamber is perfectly pure and
unmixed with air.
It has been shown by practise, that pure steam is much more easily condensed,
when in contact with cold metal surfaces, than steam mixed with air; moreover
the purity of the steam completely prevents oxydation of the sides of the
condensor.
By means of the present arrangement it is possible to utilize the heat of the
evaporated steam for further drying operations, much more easily than was the
case hitherto.
The present arrangement further shows this great advantage over the old means
of drying, that it is possible to conduct drying operations independently of other
machines or boilers, and the necessary large quantities of steam need not be
separately produced.
It is necessary for evaporating a given amount of steam from the material to
be dried, to employ at least ten times as much highly heated steam. It was
therefore hitherto impossible to use steam instead of air, in the drying of large
quantities of material. The repeated use of the steam generated by the material
itself does away with this inconvenience and the drying is rendered much simpler.
When steam, produced by an exterior source passes through the material to be

page_text: dried, the steam generated by the material is never quite saturated in leaving the
drying chamber, but takes with it a proportion of heat which could otherwise be
applied to further drying. The present invention, by frequent use of the same
steam, almost completely does away with this loss of heat. The actual object of
the present invention is therefore that instead of having to employ separately
produced steam for drying operations the same is obtained in a pure state during
said operations, and can be applied after use to further drying or the preliminary
heating of the fire gases or to any other preferred useful purpose, said purpose
not being necessarily connected with the drying apparatus.
I will now describe my invention with reference to accompanying drawing
which shows a sectional elevation of my improved drying apparatus.
It must however be expressly understood that the figure serves only to illustrate
the principle and should be considered as one of the several forms in which my
drying apparatus can be constructed.
The drawing shows an arrangement in which two drying chambers or drums
are used, same being indicated by a and r.
In the first of these chambers, a, and the adjoining spaces e, l, i and k, which are
all air-tight, the evaporation of the water contained in the material to be dried
takes place. This is effected in the following manner. The walls s of this cham-
ber are surrounded by the heated gases of the furnace p and fire-chamber n.
To obtain a more rapid evaporation, the steam is drawn from the material in
the chamber a and the space c by the exhaustor h, and the greater part thereot
is forced through into the heating tubes i where it is highly heated. The steam
then comes through the tube k back into the chamber a where it passes over the
surface of the material to be dried.
The steam loses the heat acquired in the heater i in vaporising the moisture
contained in the material, and reaches e almost saturated.
In order that the material should not come in contact with highly heated metal
surfaces and to avoid said surfaces from ever being too highly heated, the flues of
the fire chamber n first envelope the steam heater i and afterwards the actual
drying chamber a. In this way the heat of the furnace is used to best advantage.
The tube m only leads so much pure steam to the condensing box s¹ of a second
drying chamber r as is obtainable in the chamber a. The condensing box s¹ being
surrounded by fresh air, the greater part of the steam condenses in same, the
balance escaping through the exhaust pipe t, the condensed water escaping
through v.
The introduction and removal of the material to be dried occurs in circum-
stances excluding all air. The material enters at the funnel d, passes through
hopper and the worm or conveyor c, and is removed by means of the sliding
door and the hopper g.
The rotary chamber has to be rendered steam tight from the adjoining fixed
parts.
The second drying chamber r is disposed in such a way in the drawing that the
materials partially dried in a fall through the funnel g and are then completely
dried by a current of warm air from the rotary blower w.
It may be added that in cases in which the material to be dried can support
high temperatures, the steam heater i may be dispensed with, and the heating of
the steam obtained through the metallic walls which are in direct contact with
the material.
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:
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1) A device for drying suitable material characterised by the drying operations
taking place in a space void of air, and by means of steam generated from the
said material. Said steam being highly heated before it is again employed, as
herein described and set forth.

page_text: 2) An apparatus for drying, as specified in Claim 1, in which first the sides
of the steam heater and then the walls of the drying chamber are brought in
contact with the heat of the furnace with a view to avoid the overheating of the
metal surfaces enclosing the drying chamber and of the materials therein as herein
described and set forth.
3) The utilisation in an apparatus for drying, as specified in Claim 1, of the
escaping steam for further drying or for any other object until all the available
heat in the steam is entirely exhausted,
1
L.
South