Improvements in the Construction and Working of Furnaces Adapted, amongst other Purposes, for Use with Apparatus for Drying Materials of Various kinds.
Year: 1896

page_text: Date of Application, 1st Aug., 1896
Complete Specification Left, 3rd May, 1897-Accepted, 5th June, 1897
Improvements in the Construction and Working of Furnaces
Adapted, amongst other Purposes, for Use with Apparatus for
Drying Materials of Various kinds.
I, FRANKLIN DAVID CUMMER, of 1051, East Madison Avenue, in the City of
Cleveland and County of Cuyahoga, State of Ohio, one of the United States of
America, Manufacturer, do hereby declare the nature of this invention to be as
follows:--
In drying materials of various descriptions, particularly those of low value,
economy in the consumption of fuel is a matter of essential importance, and
consequently the furnace should be of such a character as to ensure the most
perfect combustion of the fuel. The purity of the heated gases and their freedom
from carbon is, moreover, particularly important where they are applied direct to,
and thus come in contact with, the material under treatment, as also for preventing
choking in the passages of the radiating system. It is also a matter of great
importance to be able to regulate the application of the heated gases, both as
regards their temperature and their, volume, whether the said gases be applied
directly or indirectly in the drying of the materials. My present improvements are
designed to comply with the conditions of working above referred to.
In a furnace adapted for employment in connection with an indirect-heat drying
system, or with a hot-air system for heating and ventilating buildings, it is
necessary to regulate the supply of air above and beneath the grate-bars. For
this purpose the discharge pipe pertaining to the fan which supplies the furnace
with air, and which communicates with the fire-box below the grate-bars, is
furnished with a regulating valve or damper. In order to effect perfect com-
bustion, I provide the furnace above the grate-bars and over the bridge with
openings for the admission of the external air; such openings being formed in the
side walls of the furnace, and being arranged so that they are not diametrically
opposite each other. The effect of the air entering through the openings so
disposed together with the draft produced by the air forced in below the fire bars
has the effect of producing a whirling motion in the heated gases from the fire;
attributable to the currents of rapidly moving air entering the furnace from
opposite sides, but not from diametrically opposite points. It is of material
advantage in working if a pressure slightly in excess of the atmosphere be
maintained in the furnace and in the several chambers comprised therein; the
object being to obtain the diffusing effect which results from pressure.
The furnace usually comprises a fire-box, a combustion chamber, a diffusing
chamber, an expansion chamber and a radiator or tube chamber. The fire-box and
combustion chamber communicate over the bridge; communication between the
combustion and diffusing chambers being established through a perforated wall.
The diffusing chamber communicates with the expansion chamber or chambers by
means of an arch provided with openings capable of being regulated or restricted.
The heated gases from the furnace after having been diffused and expanded pass
into the radiator, and thence into a passage or flue. In order to equalize the
volume of gases entering the radiator from the expansion chamber, the latter may
be provided with partitions thus forming compartments through which the heating
agent passes thereby assisting the diffusion of the gases whereby their entry into
he radiator is rendered more even.

page_text: The radiator, which is preferably of the tubular type, may be composed of
sections arranged side by side and disposed partly over the furnace or over the
expansion chamber or chambers and partly over or beneath a flue or outlet for the
cold gases. The radiator may also be formed of sections placed one above
the other; or the radiator may be one long upright tubular structure. In this
latter case, the air to be heated may be directed so that it assumes a zig-zag course
through the passages; plates or deflectors being provided for directing its course
backwards and forwards through said passages. For inducing or forcing cold air,
between the tubular sections of the radiator one or more fans may be employed.
The flue or outlet for the cold gases may be connected with a stack, or if desired a
small exhaust fan may be placed in the outlet; the degree of suction or exhaust
being so regulated in relation to the forced pressure as to induce an even flow of
the heating agent through the system. This suction together with the pressure.
produced through the furnace by means of the fan, must be so regulated in
proportion to each other that neither shall be excessive. For example, if the
pressure through the furnace be too great, the gases, and the flames of the fire, will
escape or endeavour to escape by way of the manhole-doors and any other
opening they may find; the heating agent passing to and through the radiator at a
lower temperature than is desirable, whereby the efficiency of the system is
impaired.
By moderating the pressure and regulating the suction in relative proportions
the desired diffusion of the hented gases and air may be produced, with only a very
slight and unobjectionable amount of escape (if any) of such gases and flames;
perfect combustion and perfect distribution of the heating agent resulting. If, on
the other hand, the suction or vacuum effect be too strong, the gases will be drawn
too rapidly through the radiator and will not pass evenly or equally through the
tubes thereof, but upwards and downwards through only a portion (say a quarter or
a half) of the tubes, while no gases or only a small quantity will pass through the
remainder. The result of this is that the waste gases are given off into the
atmosphere at a much higher temperature than is desirable for economical reasons;
while the heated air is delivered at a correspondingly low temperature.
It is essential to the proper working of the system that the hot gases from the
fire be regulated and diffused so thai an even temperature may prevail, under the
part of the system immediately over the furnace or expansion chamber. In order
to provide for this regulation and diffusion, a series of arches are formed; the
spaces between the said arches being restricted more or less, as found necessary, by
laying loose bricks thereon, the bricks being manipulated by means of a suitably
formed implement. The loose bricks may be dispensed with and the arches placed
at graduated distances apart. The heated gases are preferably subjected to
expansion for the purpose of lowering their temperature.
The hot gases from the fire, having been properly reduced in temperature by
diffusion and expansion are conducted to the radiator which may be located
immediately over, or at a higher or lower level than, the furnace or expansion
chamber or situated in other relation thereto. After passing upwards and
downwards through the several sections of the radiator, the said gases pass to a
cold gas flue or outlet, whence they are exhausted by means of the small exhaust
or suction fan or otherwise. The gases may be caused to pass up and down
through the radiator as often as may be desired in order that they may part with
the whole, or nearly the whole, of their heating effect. Owing to the employment
of pressure in forcing the gases through the Lubes, only a slight suction or exhaust
is required to assist the discharge of the cold or spent gases, and to avoid excessive.
pressure in the furnace. The radiator may be placed horizontally instead of
vertically; but this arrangement is not preferred.
It is sometimes necessary to reduce the temperature of the hot gases before
allowing them to enter the radiator so as to produce a slight condensation; the
object being to effect the deposit of auy incombustible solid matters the gases may
contain and prevent such matters entering and being deposited in the tubes of the

page_text: radiator the purity of the gases being enhanced, while the efficiency of the
radiator is maintained. For this purpose, the arches may be made hollow and a
current of cold air induced therethrough. Or, for the same purpose, an
additional arch or partition may be built across the diffusing chamber between
which partition and the series of hollow arches the hot gases pass; cold air being
induced into the chamber beneath the additional arch whereby the heat radiated
down is taken up. The walls may also be made hollow. In addition to, or instead
of, either the hollow arches or walls, or the additional cold air chamber, I may
employ tubes, same passing transversely through the expansion chamber. The
cold air may be drawn or forced through these air passages and may or may not.
be delivered into the heated-air conduit or shaft. The effect of this use of cold
air is to cause a slight condensation, any incombustible solid matters present in
the heating gases being taken up and deposited in the part of the furnace, which
offers greater facilities for dislodgement of such deposit.
By the employment of a system arranged and operating as above described,
perfect combustion is ensured; the hot gases being delivered from the combustion
chamber practically clean. They therefore pass through the diffusing and
expansion chamber into the radiator in such a state of purification that the
deposit (if any) formed in the tubes of the radiator is of very slow formation.
The heat of the gases is, moreover, tempered and distributed to a great degree of
nicety by the aid of the series of arches disposed at graduated distances apart, or
of the series of brick-regulated arches, and the regulating perforated plates with
which the radiator is furnished at its upper extremity. Every available unit of
heat is hereby utilized; the waste gases issuing in a condition free from carbon
and at a temperature which renders them valueless.
The herein described furnace may be employed in connection with a direct-heat
drying system, wherein the material to be dried is fed into a revolving cylinder and
placed above the expansion chamber; the heating agent being applied directly to
the material under treatment. It may also be employed in connection with a
system wherein the material is carried by trucks running preferably on rails
arranged in chambers over a tunnel or tunnels, the heating agents passing from the
furnace to the tunnel thence through perforated floors to the drying chamber or
chambers or otherwise.
The radiator or drying apparatus may, under certain circumstances, be arranged
at a distance from the furnace and the heating gases be conducted thereto by the
aid of suitable means such as a flue and fan.
Improvements in the Construction and Working of Furnaces
· Adapted, amongst other Purposes, for Use with Apparatus for
Drying Materials of Various Kinds.
I, FRANKLIN DAVID CUMMER, of 1051, East Madison Avenue, in the
City of Cleveland and County of Cuyahoga, State of Ohio, one of the United
States of America, 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 :--
In drying materials of various descriptions, particularly those of low value,

page_text: economy in the consumption of fuel is a matter of essential importance, and
consequently the furnace should be of such a character as to ensure the most
perfect combustion of the fuel. The purity of the heated gases and their freedom'
from carbon is, moreover, particularly important where they are applied direct to,
and thus come into contact with, the material, under treatment, and where it is
desirable to preserve the passages of the radiating system free from incombustible
matter tending to choke the same. It is also a point of great importance to be
able to regulate the application of the heated gases, both as regards, their
temperature and their volume, whether the said gases be applied directly or
indirectly in the drying of the materials. My improvements are designed to
comply with the conditions of working above referred to.
The accompanying drawings illustrate a furnace constructed in accordance with
the present invention, and arranged for working in connection with a radiating
system.
Fig. 1 is a vertical section taken on the line 1-1 in Fig. 2.
Fig. 2 is a corresponding transverse section on the line 2-2 in Fig. 1.
In a furnace adapted for employment in connection with an indirect-heat drying
system, or with a hot-air system for heating and ventilating buildings, it is essential
to the proper working of the furnace that the supply of forced air above and
beneath the grate-bars be capable of regulation. For this purpose, the discharge
pipe or passage a pertaining to the fan A which supplies the furnace with air, and
which communicates with the fire-box B below the grate-bars, is furnished. with a
regulating valve or damper a', and the down flues from the passage a are provided,
at or near their discharge orifices, with dampers; these dampers being so arranged
as to be readily accessible to the hand of the operator. In order to assist in
effecting perfect combustion, I provide the furnace, above the grate-bars and over
the bridge, with openings & for the admission of the external air, or of air
forced through the same by means of the fan A; such openings being formed in
the side walls of the furnace, and being arranged so that they are not directly
opposite each other. The passages which lead to the openings & may be furnished
with shutters or valves, so that the supply of air to each opening may be under
separate control. In the drawing, only une set of these openings is seen; but it
will be understood that the openings in the side of the furnace which is removed
are not placed in a direct transverse line therewith, that is to say, they are placed
at points not coincident with a transverse line drawn through those openings and
taken directly across the furnace at right angles to the wails thereof."
of the air entering from each side of the furnace through these openings bb,
together with the draught produced through the furnace by the air forced in below
the fire-bars has the effect of producing a whirling motion in the heated gases.
from the fire, on their passage through the furnace and combustion chamber and
over the bridge; the currents of rapidly moving air entering the furnace from
opposite sides, but not from directly opposite points. The air should enter
through the side openings at such a pressure as to impart to them a velocity
greater than that of the gases arising from the fire.
By these means, the consumption of all solid matters contained in the gases or
products of combustion is practically completed; the gases, which are required
for heating as hereinafter described, emerging from the combustion chamber C in
a clean or nearly clean condition. It is of material advantage in working if a
pressure slightly in excess of the atmosphere be maintained in the furnace and
throughout the several chambers comprised therein; the object being to obtain the
diffusing effect which results from pressure.
The furnace usually comprises a fire-box B, a combustion chamber C, a diffusing
chamber D, an expansion chamber E, which may be provided with partitions e for
facilitating diffusion of the expanded gases, and a radiator or tube chamber F. The
fire-box B and combustion chamber C communicate over the bridge ; while
communication between the combustion ch imber C and the diffusing chamber D is
established through a perforated wall c. The diffusing chamber D communicates

page_text: with the expansion chamber or chambers E by means of an arch or series of
arches d d; the openings therein or between them being capable of regulation or
restriction as hereinafter described. The heated gases from the combustion
chamber after having been diffused in the chamber D and expanded in the chamber
or chambers E pass into the radiator F, and thence into a passage or flue f.
The radiator F, which is preferably of the tubular type, and formed of
corrugated plates placed ridge to ridge, may be composed of any required number
of sections, arranged side by side, disposed partly over the furnace, or over the
expansion chamber or chambers E of the furnace, and partly over or beneath a flue
or outlet g for the cold gases. The sections comprising the radiator may, if desired,
be placed one above the other; or the radiator may be formed as one long upright
tubular structure. In this latter case (as also in the event of the radiator being a
long tubular structure placed horizontally), the air to be heated may be directed so
that it assumes a zig-zag course through the passages; plates or deflectors being
provided for directing its course backwards and forwards through said passages;
but I have not considered it necessary to illustrate these alternatives as various
arrangements of the radiator may be resorted to without departing from the spirit
of my invention. For forcing cold air through the tubular sections of the radiator
one or more fans H may be employed. The flue or outlet g for the cold gases may
be connected with a stack, or if desired a small exhaust fan G may be placed in
the outlet; the degree of suction or exhaust being so regulated in relation to the
forced pressure from the fan A as to assist in inducing an even flow of the heating
agent through the system. The operation of the fans A and G will be understood
from the following explanation :-The suction produced by the fan G, together
with the pressure produced through the furnace by means of the fan A, must be
s regulated in proportion to each other that neither shall be excessive.
example, if the resistance be excessive, the pressure in the furnace will increase in
like ratio, less heat will be generated, and the efficiency of the system will be
adversely affected. Moreover, owing to the increased pressure in the furnace, the
gases, and the flames of the fire, will escape or endeavour to escape by way of the
manhole-doors 62 and any other opening or outlet, such as 63, they may find. By
moderating the pressure (by means of the damper a') and regulating the suction or
exhaust effect of the fan G in relative proportions, sufficient heat will be generated
and the desired diffusion of the heated gases and air may be produced, with only a
very slight and unobjectionable amount of escape (if any) of such gases and flames;
perfect combustion and perfect distribution of the heating agent resulting. If, on
the other hand, the suction or vacuum effect be too strong, the gases will be drawn
too rapidly through the radiator and they will not pass evenly or equally through
the tubes thereof, but upwards and downwards through only a portion (say a
quarter or a half) of the tubes, while no gases or only a small quantity will pass
through the remainder. The result of this is that the waste gases are given off
into the atmosphere at a much higher temperature than is consistent with
economical working; while the heated air is delivered at a correspondingly lower
temperature.
For
1 is also essential to the proper working of the system that the hot gases from
the fire be regulated and diffused so that an even temperature may prevail under
the part of the systemn placed immediately over the expansion chamber. In order
to provide for this regulation and diffusion, a series of arches d d are formed; the
amount of free space between the said arches being governed or restricted more or
less, as found necessary; as, for example, by laying loose bricks d d thereon and
creating in effect a perforated arch; the said bricks being manipulated by means
of a suitably formed implement. The loose bricks may, however, be dispensed with,
and the arches placed at graduated distances apart, so as to provide for the required
regulation and diffusion of the hot gases; such graduation being ascertained by
observation or experiment. The heated gases are preferably subjected
expansion for the purpose of lowering their temperatures. In order to assist in
equalizing the volume of gases entering the radiator F from the expansion
to

page_text: chamber E, the latter may be provided with partitions e, thus forming
compartments through which the heating agent passes, thereby assisting the
diffusion of the gases, whereby their entry into the radiator is rendered more even
in volume at all points..
The hot gases from the fire, having been properly reduced in temperature by
diffusion and expansion in the respective chambers, pass into the radiator F, which
inay be located immediately over, or at a higher or lower level than, the expansion
chamber E, or be situated in other relation thereto, following the course indicated
by the arrows. After passing upwards and downwards through the several sections
of the radiator and through the flue f, the said gases escape into the cold gas flue
or outlet g, whence they are exhausted by means of the small or low power exhaust
or suction fan G, or otherwise. The gases may be caused to traverse the tubes of
the radiator in an upward and downward or forward and backward direction as
often as may be desired in order that they may part with the whole, or nearly the
whole, of their heating effect. Or the gases may pursue a direct instead of a
serpentine course through the radiator, whilst the air to be heated may be directed
to follow a to-and-fro path. Owing to the employment of pressure in forcing the
gases through the tubes only a slight suction or exhaust is required to assist the
discharge of the cold or spent gases, and to avoid excessive pressure in the furnace.
The radiator may be placed so that the gases pass through the same horizontally,
instead of vertically as shown; but this arrangement is not preferred.
It is sometimes necessary to further reduce the temperature of the hot gases before
allowing them to enter the radiator and so produce a slight degree of condensation;
the object being to effect the arrest and deposit of such solid or condensible
matters as the gases may contain, and to prevent such matters entering and being
deposited in the tubes of the radiator; the purity of the gases being thereby
enhanced, while the efficiency of the radiator is maintained at a high standard.
For this purpose, the arches d d may be made hollow, thus forming passages d³,
and a current of cold air induced herethrough. Or, for the same purpose, an
additional arch or partition d may be built across the diffusing chamber D,
between which partition d and the series of hollow arches d the hot gases pass;
cold air being induced into and through the chamber D', beneath the arch or
partition, whereby a certain quantity of the heat radiated down is taken up. The
walls of the diffusing chamber may also be provided with passages d' for the
circulation of cold air. In addition to, or instead of, either or any of these hollow
portions, or of the chamber D', 1 may employ tubes e', same passing transversely
through the expansion chamber E. The cold air-may be drawn or forced through
these air passages and may or may not be delivered into the heated-air conduit or
shaft. In the drawings, I have shown a flue I, connected with the discharge of
the fan H, communicating with a chamber K, whence the air is supplied to the
several hollow portions or passages and after circulating through the same passes
into the heated-air conduit or flue L. The effect of this use of cold air is to
cause a slight condensation to take place on the exterior of the parts through
which the cold air passes; any matters present in the heating gases and liable
to become deposited accumulating as a hard formation, but offering greater
facilities for dislodgement than would be the case were the condensation and
deposit to take place in the tubes of the radiator.
By the employment of a system arranged and operating as above described,
perfect combustion is ensured; the hot gases being delivered from the combustion
chamber practically clean. They therefore pass through the diffusing and expan-
sion chambers into the radiator in such a state that the deposit (if any) formed in
the tubes of the radiator is of very slow formation. The heat of the gases is,
moreover, tempered and distributed to a great degree of nicety by the aid of the
series of arches disposed at graduated distances apart or of the series of brick-
regulated arches (d); and, by means of regulating perforated plates or dampers f¹
with which the radiator is usually furnished at its extremity, the said gases may be
retained in the radiator for a longer or shorter period; or, if too great a heat

page_text: occurs at one part of the radiator, a limited flow of the hot gases may be permitted
at that part. Every available unit of heat is hereby utilized; the waste gases
issuing in a condition free from carbon and at a temperature which renders them
valueless. Air may be induced through a passage h by means of a separate small
fan or by connecting the said passage with the fan H, whereby any heat radiated.
through the roof of the flue f is taken up and utilized.
The heated air may be conducted from the radiator by means, of the flue or
passage L to a drying chamber M or it may be utilized in the heating of
apartments and buildings.
Instead of the fan H. being used to force air through the radiator it may be
placed in the passage M (see dotted lines) and used as an induction fan; the outer
end of the radiator being open to the atmosphere as also the chamber K.
The herein described furnace may be employed in connection with a direct-heat.
drying system, wherein the material to be dried is fed into a revolving cylinder and
placed above the expansion chamber; the heating agent being applied directly to
the material under treatment. It may also be employed in connection with a
system wherein the material is carried by trucks running preferably on rails.
arranged in chambers over a tunnel or tunnels, the heating agents passing from the
furnace to the tunnel thence through perforated floors to the drying chamber or
chambers or otherwise.
The radiator or drying apparatus may under certain circumstances be arranged
at a distance from the furnace and the heating gases be conducted thereto by the
aid or suitable means such as a flue and fan.
Having now particularly described and ascertained the nature of this invention.
and in what manner the same is to be performed, I claim :-
1. For use, in connection with an air-heating system, a furnace constructe:1
substantially as herein described and comprising a fire-box and combustion chamber.
into which air is forced or admitted at such relative points that a whirling motion
is created in the gases yielded, a diffusing chamber, in which the gases are tempered,.
a series of diffusing arches in said diffusing chamber, and a distributing chamber
divided into compartments respectively communicating with the various sections of
the radiator or other heating apparatus.
2. In an air-heating system of the character herein referred to, providing the.
side walls of the furnace, above the grate-bars and over the bridge, with openings,
disposed in such a manner that they are not directly opposite one another, so that,.
on air entering from opposite sides of the furnace through openings 30 disposed,
a whirling motion is produced therein, substantially as and for the purpose-
set forth.
3. In an air-heating system of the character herein referred to, providing the-
diffusing chamber with a series of arches, such as d, having the area of the free-
spaces between them regulated by means of addition il bricks, or with a series of
arches placed at graduated distances apart, substantially as and for the purpose.
set forth.
4. In an air-heating system, the combination with a furnace and a radiator, of a.
distributing chamber, and means, such as diffusing arches and partitions arranged
as shown, for regulating the temperature and the quantity of the heated gases.
passing through the several sections of the radiator, substantially as herein
described.
5. In an air-heating system, the combination of a furnace with a diffusing-
chamber, disposed beneath a series of diffusing arches and a distributing chamber
or chambers, situate between a series of diffusing arches and the radiator or other
heating apparatus, substantially as and for the purposes specified.
6. In an air-heating system of the character herein referred to, the employment,
for varying the degree of pressure, as also the diffusion of the heated gases, of an
exhaust fan in conjunction with a pressure fan whereof the discharge pipe is.
provided with regulating dampers, substantially as herein described.

page_text: 7. For arresting matters liable to become deposited from the heating gases and
so preventing their access to the radiator, the employment, in and about the
diffusing and expansion chambers, of passages, such as d', d, e', D', through which
the cold air is forced or induced; with the effect that slight condensation takes
place, and matters liable to become deposited from the heating gases are arrested
and collected upon the exterior surfaces of such hollow portions, substantially as
herein described.