Improvements in and relating to the Promotion of Combustion in Furnaces, Fireplaces, Lamps, Burners, and the like.
Year: 1896

page_text: Date of Application, 10th Mar., 1896-Accepted, 25th Apr., 1896
COMPLETE SPECIFICATION.
Improvements in and relating to the Promotion of Combustion in
Furnaces, Fireplaces, Lamps, Burners, and the like.
I, PAUL JOSEPH SCHLICHT, a citizen of the United States of America,
residing at "The Maples," Norwood Avenue, Summit, in the County of Union
and State of New Jersey, one of the United States of America, Physicist, 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 improved art or method has reference to the combustion of fuel for the
production of heat or light, and its object is to economically produce the greatest
amount of heat available for useful work or the greatest amount of light from a
given quantity of fuel.
My improved apparatus relates to means for carrying out my improved method
in the most effective manner; and its object is to provide a simple means for this
purpose, which may be applied to or embodied in existing combustion apparatus
without material alteration of their structures, and which, when applied thereto or
embodied therein, will adapt the said apparatus to be operated in accordance with
my improved method.
The new art or method consists in causing a supporter of combustion, usually
air, to flow to a place of combustion in contact with a current of hot products of
combustion, whereby the supporter of combustion is heated before it reaches the
place of combustion.
It also consists in other steps and features hereinafter described and claimed.
The new apparatus consists of means for causing a supporter of combustion to
flow to a furnace or place of combustion so as to come in contact with and be
heated by products of combustion.
It also consists of means for causing a supporter of combustion to enter a
chimney or flue and flow to the place of combustion in contact with the hot
combustion products escaping therefrom, the said means being, in some instances,
simply a deflector for initiating and introducing and directing the current of the
supporter of combustion.
It also consists iu various other devices and combinations hereinafter described
and claimed.
The invention is based upon the fact, which I have discovered, that a current of
air and a current of combustion products, will flow in contact without any
substantial intermingling, and that if a current of air is properly introduced into
a chimney or flue through which hot products of combustion are escaping, the
current of air will flow to the place of combustion in a direction opposite to that
of the current of products. The current of air will, however, gradually become
hotter, while that of the hot products of combustion will gradually become colder.
In other words, I have discovered that substantially distinct as well as oppositely
moving currents can be maintained in a comparatively confined space, such as a
furnace flue, stack, or lamp chimney, if the currents are once properly introduced
or started; and use is made of this fact and discovery in my invention for
the purpose of heating the air which is to support combustion, and for other
advantageous purposes.
In carrying out my improved method in the best way known to me, a current of
air is introduced into the channel through which hot products of combustion are

page_text: escaping, and properly directed through such channel toward the place of
combustion, so as to come in contact in said channel with the products of
combustion which are flowing in an outward direction from the place of combustion.
Under these conditions the air current when once established will maintain itself,
and during its passage will absorb heat from the escaping products of combustion
and reach the place of combustion in a heated state.
A difference of temperature
will exist between the escaping products of combustion, and the incoming air
throughout the whole length of their currents; for although the temperature of
the air gradually rises as it proceeds, still it continually comes in contact with
hotter products of combustion since the temperature of the products of combustion
is higher as the place of combustion is approached. Thus the transfer of heat
from the escaping products of combustion to the incoming air will be maintained
throughout the whole period of their contact. The current of air, being colder
than the current of combustion products, will continue to flow to the place of
combustion, while the current of combustion products will continue to flow in the
opposite direction.
Products of combustion ordinarily escape from furnaces in a very hot state, and
if their heat or a portion thereof is used to heat the feed air a direct saving will be
effected. In its broadest sense the idea of heating feed air by utilizing some of the
waste heat of the escaping products of combustion is old; that is, it is old to admit
the air through a separate duct, around which or in contact with the walls of which
the hot products of combustion are passing. In such a structure, however, it is
found to be impracticable to raise the air to the desired temperature, because the
flow of air is too rapid and because the current does not come in contact with the
escaping gases, and furthermore, the supply of air to the combustion chamber is
not regulated as it is in my method. Moreover, such a structure is complicated
and expensive.
It is well known that furnaces fed with hot air are more effective than those fed
with cold air, and that they are also more economical in the use of fuel. The use
of hot air is more economical than that of cold air, even if the said hot air has not
obtained its heat from a source of heat that would otherwise be wasted. If it is
then of advantage to feed hot air to a place of combustion when the heat is not
taken from a source of waste heat, it is evident that the process of combustion
must be much more economical when the heat imparted to the air is taken directly
from the waste products of combustion, as in my method, and not through the
walls of a separate duct; and also when the air thus heated is carried to the place
of combustion by gravity and in regulated quantities, as in the best form of my
method, and not under the pressure of a forced. or even a natural draft that sweeps
combustible elements from the furnace into regions of lower temperature before
they can be consumed, thereby carrying away units of heat that would otherwise
be available for useful work.
There is a further advantage secured by my improved method as a result of
supplying hot air to the place of combustion in regulated quantities from above the
fire. It is that diffusion of gases is aided and combustion regulated and improved.
The more intimately the molecules of the combustible gases are intermingled with
those of oxygen, the greater will be the number of atoms that unite in chemical
union. A thorough diffusion of the gases and the air, and a regulated supply of
air to the gases are secured by my invention.
In the best form of my invention the supply of air to the place of combustion is
automatically regulated. This automatic regulation is the result of the inter-
dependence of the actions of the chemical operations within the place of combustion,
and of the inflowing air and outflowing products of combustion. The intensity of
combustion and the volume, temperature, density, and general conditions of the
- current of products of combustion, are affected and governed by the volume,
.temperature, density, and general conditions of the air curreut, and the volume,
temperature, density and general conditions of the air current are themselves
directly affected and governed by the intensity of combustion, and the volume,

page_text: temperature, density, and general conditions of the current of combustion products.
The propulsive force is the pressure of the atmosphere, and since this pressure is
practically constant, the flow of air to the place of combustion will be in all
particulars uniform unless there are variations in the volume, temperature, density,
or general conditions of the column of escaping products of combustion within the
stack or duct.
In ordinary processes of combustion an excess of air, which does not contribute
to the support of combustion, is always admitted to the combustion chamber, and
this air accomplishes nothing more than to absorb and carry away from the
apparatus units of heat which otherwise would be available for a useful purpose.
By my method the wasting of these units of heat is avoided.
It is well known that in ordinary methods of combustion particles of carbon
are liberated and carbon monoxide and other combustible gases are evolved which,
because of an inadequate supply of oxygen, escape up the stack or, if sufficient
oxygen is present to consume them, their temperatures are reduced below the
point of ignition before the oxygen is thoroughly diffused through the furnace.
in which case both the uncombined oxygen and the combustible elements escape.
By supplying a portion of the air above the fire-bed I establish such conditions
as will prevent this loss of valuable fuel.
The term "furnace" is used herein in the generic sense, and is meant to include
not only furnaces that burn solid, liquid and gaseous fuel, but also lamps and
gas burners for illuminating purposes where chimneys are used in connection
with these means for illumination; for I have discovered that by the proper
application of my invention to au illuminating apparatus the efficiency and economy
thereof can be greatly increased.
In practice, the air will usually be admitted at or near the top of the flue,
but its admission is not necessarily limited to this position. The advantage of
introducing the air at the top of the flue is that the current of air is subjected
to the action of hot gases throughout its entire length and thus its temperature
is raised much higher than would be possible if it were introduced at a lower
point.
In the preferred practice of my improved method the fire is first started in
the combustion chamber, the draft doors being left open for this purpose. After
the fire is well started the draft doors are entirely or very nearly closed so as to
cut off or very much reduce the supply of air beneath the grate. As soon as this
is done the velocity of the escaping products of combustion is reduced, the air
enters the stack or chimney, and, by means of the deflector is given an initial
direction down the stack and flows toward the fire chamber in contact with the
escaping products of combustion which are passing in the opposite direction, and
flows into the fire chamber where it immediately units with the fuel. The effect
of closing or partially closing the ashpit doors, is to cause the atmospheric pressure
to be exerted wholly through the stack, or to preponderate therein to such an extent
that the effect of the ordinary atmospheric pressure at the initial part of the air
current will not be neutralized by the atmospheric pressure exerted from below.
Sometimes the best results are obtained, however, by regulating the inflow of air
at the ashpit doors in accordance with the needs of the solid combustible elements
which remain after destructive distillation of the fuel has occurred. While the
supply of air to the ashpit doors is thus arbitrarily proportioned to the needs of the
solid fuel, the supply of air to the combustible gases within the combustion chamber
will be automatically regulated as before stated. It may not ordinarily be necessary
to admit air through the ashpit doors when fresh fuel is added to the fire, although
if the quantity of added fuel be large, the attendant may find it advantageous with
some fuels to admit a portion of the air in this manner. The best results are
obtained by adding only very thin layers of fresh fuel and by leaving the ashpit
doors closed or nearly closed.
Another great advantage which is secured by my invention is the abatement
of the smoke nuisance, for by feeding air to the fuel in the manner described,

page_text: carbon which usually escapes and is deposited in the form of soot is:
entirely, or substantially, consumed, and the products of combustion escaping from
the stack are either perfectly clear or but slightly colored by non-combustible
substances which are found in some fuels to a greater or less extent.
Having thus fully described my improved method, I shall now describe my
improved means for carrying the same into effect.
Referring to the drawings,
Figure is a sectional view of an ordinary boiler furnace and stack, the stack
being provided with one form of deflector for initiating an air current.
Figure 2 is a sectional view of the stack, and a deflector provided with a wind
guard.
Figure 3 is a sectional view of a stack, a deflector, a wind guard, and a stack
protector and air heater.
Figure 4 is a similar sectional view showing the stack protector anl air heater
as encircling only the top of the stack.
Figure 5 is a sectional view of a modification of the wind guard and the stack
protector and air heater.
Figure 6 is a perspective view of a modified form of deflector.
Figures 7, 8, 9 and 10 show devices which contain, in addition to the elements
shown in the preceding figures, means for extending the stack.
Figures 11, 12 and 13 show chimneys or globes for illuminating burners.
In Figure 1, 1 designates a horizontal tabular boiler of the ordinary form; 2, a
grate for supporting fuel to heat the same; 3, the ash pit beneath the grate, and
4, the bridge wall at the back of the fire chamber, the ash pit being provided with
the usual doors. 5 designates a stack of. any convenient form which has com-
munication with the fire chamber through the breeching and flue 6, which flue
enters an opening 7 in the side of the stack.
An air deflector, 8, is placed in the stack at its top for introducing a current of
air and directing the same down the stack. An additional deflector, 9, may be
placed at the point where the breeching communicates with the chimney to direct
the descending current through an opening 10, controlled by a damper 11, operated
by a rod 12, but this additional deflector is not essential.
Dotted lines are drawn within the chimney and breeching to indicate graphically
the path described by the descending current of air; the direction being further
indicated by the arrows 13. The path described by the products of combustion is
indicated by the arrows 14. The arrows 13 and 14 serve a like purpose in all the
figures of the drawing.
15 designates the top of the stack, and 8 the means for admitting and directing
the current of air. This means conforms to the shape of the stack, and is of such
a size as to enter the top of the same and leave a space between it and the stack,
and it is adapted to extend both above and below the top of the stack. It here
consists of a tube somewhat smaller than the stack, one end of which extends a
short distance down the stack, and the other a short distance above its top, and
supported in any convenient manner. By this means an annular channel 16 is
formed between the stack and tube 8, through which the cold air is introduced,
and by which it is given direction. In this form of apparatus the air current
will entirely surround the gaseous current, and thus much more effectively absorb the
heat of said gaseous current than will an air current of any other form.
The operation is as follows: The fire is started in the usual manner, with all the
valves and doors which control the draft open, so that the fuel may receive a full
supply of oxygen from beneath the grate. When the fuel is thoroughly ignited
and the fire is well under way, the ash pit doors are nearly or entirely closed so as
to greatly restrict or entirely shut off the supply of air beneath the grate. As
soon as the doors are thus manipulated, the velocity of the current of gases escaping
through the stack will be greatly reduced. Air will enter and descend the stack
in distinct currents in immediate contact with the hot products of combustion, thus
reaching the combustion chamber in a heated condition. The air may flow from

page_text: the stack to the combustion chamber through any suitable channel; as, for instance,
through an opening arranged between the combustion chamber and the breeching,
or if such an opening is not provided, it may flow through the lower part of the
passage or fue connecting the stack and the combustion chamber.
In general,
the air current will always establish itself in that part of the flue where it meets
with the least resistance from the escaping gases. In vertical flues, such as
ordinary stacks, the path of least resistance will be at the sides, while in passages
which are inclined or horizontal it will be in the lower part. Hence, when a
construction, such as that shown in Figure 1 is used the air current will probably
follow the course indicated by the arrows 13. That is, it will enter the stack
through the annular channel 16, descend along the wall, as indicated graphically
hy the arrows, fill the lower part of the stack, flow through the lower part of the
breeching, and reach the fire chamber through the opening 10.
In Figure 2, is shown the upper part of the stack 15, to which is applied another
form of attachment. In this instance the attachment comprises a tube or deflector 8.
extending down within the top of the stack, the upper extremity 17 being bent
over to form a wind guard 18, so that the air enters in the direction shown by the
arrow 13, and is deflected and directed as with the device before described.
Figure 3 shows a stack provided with a tubular deflector 8 situated centrally
within the top of the stack, the top of said deflector merging into a wind guard 18.
which curves over the top of the stack and terminates in a cylindrical stack pro-
tector and air heater 19 which is of substantially the length of the stack and
encircles and is spaced from the stack so that a current of air may pass upward in
contact with the walls of the stack and become heated before it reaches the
deflector. The air within the space between the stack and the cylindrical stack
protector serves to prevent heat from passing by conduction to the protector, and
the protector itself serves to further prevent the cooling of the stack. This function
is very important, because the hotter the stack the greater will be the quantity of
heat imparted to the current of air which flows downward in contact with the
interior surfaces of the stack.
Figure 4 embodies the same construction as Figure 3, but in this form of che
apparatus the protector 19 is of considerably less length than the stack. The
general operation of the two devices is the same.
Figure 5 shows a perspective view of a portion of a stack 5, provided with an
annular jacket 20, which terminates below the top of the stack. The stack itself
deflects the air downward within the jacket (as indicated by the arrows 13), whence
it enters the stack and is directed to the furnace as desired. The air in descending
the jacket will obviously be raised in temperature by coming in contact with the
heated wall of the stack. From the jacket the air is conducted into the stack in
any desired manner, as, for example, through the holes 21 in the stack, and is then.
given proper direction by the deflector 8.
Figure 6 is a perspective view of the stack having three deflector tubes 22,.
fitted within the same upon the right-hand side, and a similar tube 23 fitted to the
outer wall at the left-hand side; and having, in addition, a bent tube 24 applied
thereto, which is simply hung upon the top of the stack, and, if necessary, fastened
in that position. Here the tubes 22 and 23 are formed with horizontally disposed
ends. The tubes 22 and 24 are shown extending a suitable distance within the
stack, the air, before escaping therefrom, being heated to a greater or less extent
indirectly by the rising products of combustion, and after passing from the tube,.
being still further heated by coming into direct contact with the products of com-
bustion. The tube 23 is upon the outside of the stack, the intention being to have
it enter the same at any desired point. In this position the tube is heated by
conduction from the stack and, in turn, heats the air which passes through it.
When the tube enters the stack, a deflector 25 is used to give direction to the
entering current of air.
Figure 7 shows a tubular deflector 8 which is continued upward so as to form an
extension of the stack. The wind guard 18 extends from the side of the deflector

page_text: and over the top of the stack. The stack protector 19' is of tubular form and
hangs pendent from the wind guard, there being, of course, a space between it and
the stack. The protector is shown as a short one, but may be of any desired
length. This form of device I term a "stack extender," and its function is to
improve the draft of stacks in which the draft is defective because the stacks are
too short.
Figures 8 and 9 show a detachable stack extender which consists of a tabe 26,
that is of the same diameter as the stack and of appropriate length. It may be
riveted to the stack or otherwise secured thereto. Within this extender is
situated a somewhat smaller tube 8 that extends above the top of the same, so as
to still further extend the stack and is supported by arms 27 which rest upon the
top of the tube. In this form of device the air and smoke passages are thus both
lengthened.
Figure 10 shows a stack extender somewhat like that of Figures 8 and 9. In
this form, however, the wind guard 18 is curved so as to form a chamber of
considerable size, and the supporting arms are secured to the lower edge of the
wind guard and to the lower end of the tube 26.
The stack protector may, in any of the forms of apparatus, be made of some
Bon-heat-conducting material.
The chimneys or globes of Figures 11, 12 and 13 are adapted to discharge
products of combustion from illuminating apparatus or burners, and to heat and
supply air to the flames thereof.
Figure 1 shows a bulging glass chimney 28, which has openings 29 at its top,
and which is further provided with an interior and smaller tube 8 which depends
from the top thereof so as to form within it a passage for escaping products of
combustion, and around it another passage for the air that first becomes heated and
then flows to the burner to support the combustion which produces illumination.
Figure 12 shows a cylindrical chimney and a small tube 8 of the same form,
which is secured to the latter by webs 30, which are formed in the process of casting
the chimney.
Figure 13 shows a globe or chimney which is in the form of two truncated
cones, with abutting bases. The tube 8' in the top part of the globe slightly
flares at its lower end so as to deflect the entering air to the sides of the globe
whereby its flow is rendered steady and its heating by contact with the walls of
the globe insured.
In all these three forms of apparatus, the effect of the introduction and heating
of the air is to increase the brilliancy of the flame and to prevent the escape of
noxious odors into the apartment where the apparatus are used.
When in the claims I use the term "deflector" I refer to any means whereby an
independent current of air may be initiated within a stack or chimney containing
a current of products of combustion and flow in a direction opposite to that of the
latter current.
In placing or arranging the deflectors, the smoke passage should not be too
greatly restricted; for if it is too small the smoke will be forced to escape to the
air passage as well as through that intended for the smoke. Generally it will not
do to reduce the smoke passage to less than half its normal size. The best results
.are generally secured by making the smoke passage considerably larger in area
than the passage for the air. It is better that the flue for carrying off the smoke
shall extend above that for introducing the air.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
1. The improvement in the art of producing combustion which consists in causing
a supporter of combustion to flow to a place of combustion in contact with a current
of products of combustion, substantially as set forth.
2. The improvement in the art of producing combustion which consists in causing

page_text: a supporter of combustion to flow by gravity to igneous fuel in contact with products
of combustion, substantially as set forth.
3. The improvement in the art of producing combustion which consists in feeding
to the place of combustion below the top of the fuel a portion only of the air
required for combustion, and in causing the remainder of the air required for
combustion to flow to the place of combustion in contact with a current of the
products of combustion flowing therefrom throughout a substantial part of the
length of said current, substantially as set forth.
4. The combination with a furnace or place of combustion, of means for feeding
a supporter of combustion to the furnace or place of combustion, so as to come
in contact with and be heated by products of combustion, substantially as set
forth.
5. The combination with a furnace or combustion chamber, of a chimney and
means for causing a supporter of combustion to enter the chimney and flow to said
furnace or combustion chamber, so as to come in contact in said chimney with the
hot products of combustion flowing from the furnace or combustion chamber,
substantially as set forth.
6. The combination with a combustion apparatus, of means for feeding air
by gravity to the said apparatus through the stack, flue or chimney thereof, so as to
cause the air to come in contact in said stack, flue or chimney with the hot
products of combustion escaping from the combustion chamber, substantially as set
forth.
7. The combination with a furnace and stack, of a deflector situated in or upon
the stack, and adapted to produce an air current in the stack in a direction
opposite to the direction of motion of the products of combustion, and to separate
the initial portion of such air current from the products of combustion, substantially
as set forth.
8. The combination with a chimney or stack, of an air deflector conforming to
the shape of the same and of such a size as to enter the top of the chimney or stack
and leave a space between it and the chimney or stack, and supported so as to
extend above the chimney or stack, substantially as set forth.
9. The combination with a chimney, of a deflector consisting of a tube extended
a part of the way down within the top of the same to direct au entering current of
air downward therein, substantially as set forth.
10. The combination with a combustion chamber, of means for admitting below
the top of the fuel in said chamber a portion only of the air required for com-
bustion, and a chimney or flue connected with the combustion chamber and
provided with means for causing the remainder of the air required for combustion
to enter the chimney or flue and flow through the same to the combustion
chamber in contact with the escaping products of combustion, substantially as set
forth.
11. The combination with a chimney or stack of means for causing a current of
air to move downwards within said chimney or stack in contact with the products of
combustion, and a chimney or stack extender adapted to lengthen the passage
through which the products of combustion flow, substantially as set forth.
12. As a new article of manufacture, a chimney attachment provided with
means for causing a current of air to flow downward through a chimney or flue,
substantially as set forth.
13. As a new article of manufacture a chimney attachment having a wall which
divides the same into two flues, one of said flues being adapted to initiate a down-
wardly moving air current, and the other flue being adapted to receive an upwardly
moving current of products of combustion, substantially as set forth.
14. The combination with a chimney or stack, of an air inlet pipe extending into
the chimney or stack, and adapted to introduce a current of air and direct it
towards the place of combustion, substantially as set forth.
15. The combination with a chimney or stack, of means for causing a current of
air to move downward within said chimney or stack in contact with the products of

page_text: combustion, and an air heating device adapted to receive heat from the said
combustion products and to deliver heated air to said means, substantially as set
forth.
16. The combination with a chimney or stack, of means for initiating a down-
wardly moving current of air within said chimney or stack, so that it will flow
downward in contact with the products of combustion, and an air heating device
consisting of a chimney or stack protector adapted to protect the chimney or stack
from the external atmosphere and to deliver heated air to said means, substantially
as set forth.
17. The combination with a chimney or stack, of means for initiating a down-
wardly moving current of air within said chimney or stack so that it will flow
downward in contact with the products of combustion, and an air heating device
adapted to receive heat from the combustion products within the chimney or stack
and deliver heated air to said means, and a wind guard adapted to protect said
current from the wind, substantially as set forth.
18. The combination with a chimney or stack, of means for causing a current of
air to move downward within said chimney or stack in contact with the products of.
combustion, and a wind guard adapted to protect said current from the wind,
substantially as set forth.
19. As a new article of manufacture, a chimney or globe provided with means
for causing air to flow downward within the same to the place of combustion in
contact with the products of combustion, substantially as set forth.
20. As a new article of manufacture, a lamp chimney or globe increasing in
diameter below the top, so as to form an cnlarged portion or chamber, and
provided with a deflector increasing in diameter towards its lower end, and thereby
adapted to cause a current of air to enter the chimney or globe and pass downward
along the sides of the chimney or globe to the place of combustion, substantially as
.set forth.
Deted this 10th dor of Merah 1806
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.