Improvements in Apparatus for Drying Granular and other Material.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Drying Granular and other Material.
I, DR. CARL GUSTAV JOBST MÖLLER, of No. 19 Friedrich-Wilhelmstr. Berlin,
W, in the Empire of Germany, Manufacturer, do hereby declare the nature of this
invention to be as follows:-
This invention relates to drying plant, wherein means are provided for bring-
ing the combustion gases from a furnace, or whatever other hot gases may be
available, into immediate contact with the material to be dried; the object it is
proposed to attain by the novel arrangement being, to conduct the said gases
through the same charge of material not once only-as hitherto-but repeatedly;
and, prior to each of their successive passages through the drying chamber, to
mix such gases with others, freshly supplied from the furnace; such quantities
only of the combustion gases being allowed to escape, as are required to be
discharged, to enable fresh products of combustion to be admitted.
Owing to this mixture of the combustion gases,-after they have once passed
through the material to be dried,-with fresh combusuon gases, the temperature of
such gases, as they enter the drying chamber, may be exactly controlled and
adjusted, without the aid of any supply of cold air and, consequently, without any
loss of heat; while at the same time the quantity of air conducted through the
furnace need only be just sufficient for the rational combustion of the fuel employed
to effect desiccation; and, furthermore, the gases arising from the plant may be
discharged in a perfectly saturated condition and at a high temperature or, in
other words, whilst very rich in moisture.
The drying apparatus comprises a drying chamber, adapted to be closed by
doors at both ends.
The gases, as they are evolved in the furnace, pass, over the fire-bridge, into the
distributing channel or flue; but, even as they pass they mix with the gases which
meet them as they issue from the channel or flue; and, jointly with these, they
pass through perforations in the sole-plate and enter the drying chamber, traverse
the materials to be dried, and then pass off, through apertures in the roof of the
chamber, into the collecting channel or flue; whence, by the action of a pan, the
greater part of them is forced back into the flue, while the remaining minor part
is expelled into the outer atmosphere through an adjustable outlet. The gases
thus returning through the flue, which are saturated with steam,-upon arriv-
ing at a point near the furnace, once more mix with hot gases fresh from the
furnace, and are thereby rendered capable of again absorbing water-vapour, as
they next pass through the material being dried.
-
The temperature of the gas-mixture, at the said point may be precisely adjusted
by means of dampers.
The wider the two dampers are opened, the greater will be the amount of hot

page_text: combustion gases which will meet the circulating gas-current, and the higher the
general temperature of the inner chambers as well as the temperature of the gases
issuing at the flue.
The oxygen of the current of air flowing through the furnace is never totally
exhausted, after such air has passed through the fuel once. Wherever combus
tion is conducted on rational principles, the fire gas to be supplied with a
considerable quantity of air in excess, if complete combustion is to be ensured.
Where the surplus, thus admitted to the fire, consists of cold air, a certain loss
of heat is generally the result. But in a modified arrangement such loss of heat
is avoided, or at all events considerably reduced.
The combustion gases pass through the drying chamber in the direction of its
length. The gases drawn off by a fan are for the most part, forced back through
the return flue, while the smaller remaining portion thereof is expelled through
the adjustable outlet. From the return-flue a connecting channel leads down to the
ash-box of the furnace, so that part of the returning gases may be brought
under the grate. By means of dampers, the operation may be so regulated that the
air is set in energetic motion in the drying chamber, while the quantity of air
admitted under the grate is only just sufficient to keep up combustion.
In order to enable the space occupied by the drying plant to be used to the
best advantage, the materials to be dried may, if necessary, be placed in the return
flue. Where the course of the combustion gases is as stated, the drying chamber
may, if need be, assume any other than the shape herein described.
The apparatus may be arranged for drying granulated or powered material,
such apparatus comprising a rotary drum-cylinder. The material to be dried
is admitted through a hopper, descends along the inclined drum or barrel, and
is carried off, at the opposite end by means of either a conveyor-screw or any other
suitable device. The hot gases, evolved on the grate, mix, with the gases return-
ing through the flue, and are forced by the fan through the drum; only part of
such gases escaping into the atmosphere, while the greater part of the same is
driven through the return flue, and then, after mixing with fresh combustion
gases, made to resume the same course as before.
In another modification of the drying apparatus I provide a rotary drum (barrel
or cylinder). This apparatus has this feature in common with 'the arrangement
above described, that a connection is provided between the return flue and the ash-
box of the furnace. The fresh air admitted is here. however, subjected to a
preparatory heating process in a register-heater, mixes with the return-gases in
the fan, and, either flows to the drum-cylinder direct,-through the flue only,-or,
through the flue and the said connection to the furnace. The gases escaping are
sent through the register and yield up both their free and latent-heat to the in-
coming fresh supply of air, that surrounds, and moves in contact with, the heat-
ing registers. The condensation water, descending as the exhaust-gases become
cooled, is conducted outside through the discharge-orifice. The fan is located in
the cooler portion of the drying apparatus wherever the treatment of the material
in the drum is to be conducted at very high temperatures.
A further modification comprises a drying apparatus consisting of a revolving
drum, wherein the current of air and the material to be dried pass through such
drum, in opposite directions. The exhaust gases escaping and saturated with
water-vapour, are again conducted through heating registers and there give up
their free and latent heat to the fresh air entering at the inlet and admitted under
the fire-grate in the furnace.
Lastly, a still further modification comprises a double-drum (or "compound")
drying arrangement, wherein as regards the lower drum-the combustion gases
follow precisely the same course as hereinbefore mentioned.
The gases escaping are conducted through a register-heater and there give up
their heat to a powerful current of air surrounding, or moving in contact with, 5
the register; such current of air being generated by a second fan and serving for
a preliminary drying and heating process, to which the material is subjected in

page_text: the unner drum. The condensation water is discharged at the lower part of the
register heater.
Deted this 13th day of Norambar 1806
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.
Improvements in Apparatus for Drying Granular and other Material
I, DR. CARL GUSTAV JOBST MÖLLER, of No. 19 Friedrich-Wilhelmstr. Berlin,
W, in the Empire of Germany, Manufacturer, 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 relates to drying plant, wherein means are provided for bring-
ing the combustion gases from the furnace, or whatever other hot gases may be
available, into immediate contact with the material to be dried, the object it is
proposed to attain by the novel arrangement being, to conduct the said gases
through the same charge of material not once only-as hitherto but repeatedly;
and prior to each of their successive passages through the drying chamber, to
mix such gases with others freshly supplied from the furnace; such quantities
only of the combustion gases being allowed to escape as are required to be
discharged, to enable fresh products of combustion to be admitted.
Owing to this mixture of the combustion gases, after they have once passed
through the material to be dried,-with fresh combustion gases, the temperature of
such gases
as they enter the drying chamber, may be exactly controlled and
adjusted without the aid of any supply of cold air and, consequently, without any
loss of heat while at the same time the quantity of air conducted through the
furnace need only be just sufficient for the rational combustion of the fuel employed
to effect desiccation; and, furthermore, the gases arising from the plant may be
discharged in a perfectly saturated condition and at a high temperature or, in
other words, whilst very rich in moisture.
The drying apparatus is represented in the accompanying drawings in which,
Figure 1 is a longitudinal section of the apparatus
Figure 2 is a transverse section of the same.
Figures 3 to 7 shew modified forms of apparatus hereinafter described.
The apparatus shewn in Figures 1 and 2 comprises a drying chamber a adapted
to be closed by doors m n at both ends.
The gases, as they are evolved in the furnace b, pass over the fire-bridge, into
the distributing channel, or flue h; but, even as they pass the point g, they mix
with the gases which meet them as they issue from the channel or fluc c; and,
jointly with these, they pass through perforations in the sole-plate and enter the
drying-chamber a, traverse the materials to be dried, and then pass off through
apertures in the roof of the chamber, into the collecting channel or flue i; whence,
by the action of a fan d, the greater part of them is forced back into the flue c
while the remaining minor part is expelled into the outer atmosphere through an
adjustable outlet e. The gases thus returning through the flue c,--which are
saturated with steam, upon arriving at g, once more mix with hot gases fresh
from the furnace, and are thereby rendered capable of again absorbing water-
vapour, as they next pass through the material being dried.
The temperature of the gas-mixture, at y may be precisely adjusted by means of
dampers e and f.
The wider the two dampers are opened, the greater will be the amount of hot

page_text: combustion gases which will meet the circulating gas-current, and the higher the
general temperature of the inner chambers as well as the temperature of the gases
issuing at e.
The oxygen of the current of air flowing through the furnace 6 is never totally
exhausted, after such air has passed through the fuel once. Wherever combustion
is conducted on rational principles, the fire has to be supplied with a considerable
quantity of air in excess, if complete combustion is to be ensured. Where the
surplus, thus admitted to the fire, consists of cold air, a certain loss of heat is
generally the result. But in the arrangement shewn in Figure 3 such loss of
heat is avoided, or at all events considerably reduced.
The combustion gases pass through the drying chamber in the direction of its
length. The gases drawn off by the fan d are, for the most part, forced back
through the return flue c, while the smaller remaining portion thereof, is expelled
through the adjustable outlet e. From the return flue c a connecting channel k
leads down to the ash-box of the furnace b, so that part of the returning gases may
be brought under the grate. By means of dampers e, k, l and f the operation may
be so regulated that the air is set in energetic motion in the drying chamber a,
while the quantity of air admitted under the grate at f is only just sufficient to
keep up combustion.
In order to enable the space occupied by the drying plant to be used to the best
advantage, the materials to be dried may, if necessary, be placed in the return
flue c
Where the course of the combustion gases is as stated, the drying chamber may,
if need be, assume any other than the shape here shewn.
In Figure 4 apparatus for drying granulated or powdered materials, is
represented, such apparatus comprising a rotary drum-cylinder a. The material
to be dried is admitted through a hopper m, descends along the inclined drum or
barrel, and is carried off at n by means of either a conveyor-screw or any other
suitable device. The hot gases, evolved on the grate b, mix at g, with the gases
returning through the flue c, and are forced by the fan d through the drum a;
only part of such gases escaping into the atmosphere at e while the greater part
of the same is driven through the return flue c, and then, after mixing with fresh
combustion gases, made to resume the same course as before.
In Figure 5 drying apparatus with a rotary drum (barrel or cylinder) a is shewn
which has this feature in common with the arrangement represented in Figure 3,
that a connection is provided between the return flue c and the ash-box of the
furnace b. The fresh air admitted at f is here, however, subjected to a preparatory
heating process in a register-heater o, mixed with the return gases in the fan d,
and, either flows to the drum-cylinder direct or through the flue c only,-or
through c and k to the furnace b. The gases escaping at e are sent through the
register o and yield up both their free and latent heat to the in-coming fresh
supply of air, that surrounds, and moves in contact with the heating registers. The
condensation water, descending as the exhaust-gases become cooled, is conducted
outside through the discharge-orifice p. The fan d is located in the cooler-portion
of the drying apparatus wherever the treatment of the material in the drum is
to be conducted at very high temperatures.
Figure 6 shews drying apparatus comprising a revolving drum a, wherein the
current of air and the material to be dried pass through such drum in opposite
directions. The exhaust gases escaping at e and saturated with water-vapour, are
again conducted through heating registers o, and there give up their free and latent
heat to the fresh air entering at f, and admitted under the fire-grate in the
furnace b.
Lastly, in Figure 7 there is shewn a double-drum (or 'compound') drying
arrangement, wherein-as regards the lower drum-the combustion gases follow
precisely the same course as in Figure 4.
The gases escaping at e are conducted through a register heater o and there give
up their heat to a powerful current of air surrounding, or moving in contact with

page_text: the register, such current of air being generated by a second fan r and serving for
a preliminary drying and heating process, to which the material is subjected in
the drum q. The condensation water is discharged at p.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is:-
1. Drying apparatus with means for conducting the combustion gases through
the material to be dried; the essential feature of such apparatus being that part of
gases, as they leave the material being dried, are, by means of a fan (such as d)
conducted back through a return channel or flue (such as c) and mixed with fresh
combustion gases as they issue from the furnace (b); for the purpose of reducing
the temperature of the gases arising from the fire, whilst avoiding loss of heat, and
of only conducting as much air through the furnace (b) as is requisite for the
advantageous combustion of the fuel.
2. In drying apparatus, such as characterized by the 1st Claim, enlarging the
return flue (such as c), so as to make it serviceable as a drying chamber, and to
toke full advantage of the space occupied by the drying plant.
3. In drying apparatus, of the class referred to, in the 1st Claim, the provision
of a connecting channel or flue (such as k Figures 3 and 5) between the return
flue (c) and the ash-box of the furnace (b); for the purpose of enabling the air
olmitted, to be, both conducted under the grate, and mixed with the combustion
gases above the grate.
4. In drying apparatus of the class referred to in the 1st Claim (Figures 5 and 6)
the provision of heating registers (such as o), which are heated by the warm
gases which issue from the drying apparatus at e, and are saturated with steam;
they yielding up such heat to the air entering at f and surrounding the heating
registers, for the purpose of utilizing the free and latent heat of the exhaust gases
and of collecting the condensation-water discharged at p.
5. In drying plant of the class referred to in the first Claim (Figure 7) the
arrangement of heating registers (such as o), which are heated by the warm gases
issuing from the drying apparatus at e and saturated with steam, and adapted to
yield up such heat to a current of air generated by a fan (such as r) and couducted
through a second drying-chamber q, for the purpose of utilizing the free and latent
heat of the exhaust gases in submitting the material under treatment to a
preparatory heating and drying process.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.