Improvements in Furnaces or Stoves for Heating and other Purposes.
Year: 1896

page_text: Date of Application, 27th Feb., 1896-Accepted, 3rd Oct.. 1896
COMPLETE SPECIFICATION.
Improvements in Furnaces or Stoves for Heating and other
Purposes.
We, THOMAS HOCKING LUCAS, No. 56 10 Street South, Minneapolis,
Minnesota, United States of America, Carpenter and HENRY BOOTH MARTIN,
No. 43 B Street Washington District of Columbia, United States of America,
Editor, do hereby declare the nature of this invention and in what manner the
Eame is to be performed, to be particularly described and ascertained in and by the
following statement:-
The object of the invention is to provide a new and improved furnace that
shall be durable in construction, arranged to insure complete combustion, and to
utilize the fuel to the fullest advantage.
The invention consists of a primary combustion chamber communicating with the
fire pot and having a contracted outlet at its top, said chamber being provided with
means for supplying air thereto, and a secondary combustion chamber surrounding
the primary combustion chamber and communicating therewith through its contracted
outlet.
The invention also consists of certain parts and details and combinations of the
same, as will be fully hereinafter described.
Referring to the accompanying drawing in which similar letters of reference
indicate corresponding parts in both the figures,
Figure 1 is a sectional front elevation of the improvement, on the line 1-1 of
Figure 2; and
Figure 2 is a sectional side elevation of the same, on the line 2-2 of Figure 1.
The improved furnace is provided with an exterior shell A, supporting a fire
box 13, below which is arranged an ash-pit C, and above which, is arranged the
prinary combustion chamber D, preferably arched, as indicated in Figure 1, and
of a sufficient size to permit a thorough mixing of the air with the products
of combustion before they escape therefrom for a purpose hereinafter described.
A suitable door A' at the front of the shell A, opens into the lower part of the
combustion chamber, to permit of placing fuel in the fire box B, and a door A
is arranged in the lower part of the shell A, to give access to the ash-pit C to
remove ashes therefrom whenever necessary.
The ash-pit C, fire box 13 and primary combustion chamber D are ordinarily
closed; and in the apex or top of the said combustion chamber D are formed
openings D' adapted to be closed by a damper D', fitted to slide, and secured on a
rod D extending to the outside of the shell A to be under the control of the
operator. The openings D' when the damper D' is open, lead into a secondary
combustion chamber E surrounding the sides of the combustion chamber D, the
fire box 13 and the ash-pit C, the said secondary combustion chamber also
extending under the ash-pit C as at E, and from the rear end of this chamber
extension E leads a short pipe E' connected with a chimney or draft flue F.
The necessary air for combustion is supplied to the fire box D, through the pipes G
extending in the lower part of the chamber E, and connected at their lower ends
through the sides of the shell A, with the outer air, while the inner upper ends
discharge into the primary combustion chamber at opposite sides thereof or at the
front or back or around the said combustion chamber as adaptation to use and form
of construction may require.

page_text: Suitable valves G' are arranged over the inlet openings of the pipes G, to control
the amount of air passing from the outside through the pipes G. into the primary
combustion chamber.
In the top of the arched primary combustion chamber D is arranged, when an
extra supply of superheated air is necessary to insure more perfect combustion, a
longitudinally extending pipe H, into which discharge the upper ends of the pipes I,
extending through the upper part of the secondary combustion chamber E, to then
pass at their lower ends through the sides of the shell A to connect with the
outer air, the inlet of the air to the said pipes I being controlled by suitable
valves 1, similar to the valves G¹.
The rear end of the primary combustion chamber D is connected by a short
flue J, with the chimney F, and in this short flue J is arranged a damper K,
which when open, gives à direct draft from the said combustion chamber to the
chimney. Normally, however, this damper K is closed.
Now, when the furnace is in operation, the air necessary for combustion is
supplied to the burning fuel by the pipes G and I, nud the air, in its passage. from
the outside to the primary combustion chamber by the said pipes G and I, is heated
as the pipes extend through the hot air chamber E. When the valve or damper D
is open, then the products of combustion in the primary combustion chamber D,
passes through the openings D' into the upper end of the secondary combustion
chamber E, to then travel downward to the sides of the primary combustion
chamber D, fire box 13 and ash-pit C, around the bottom thereof, to finally pass to
the extension E into the chimney F.
Now, the products of combustion travelling through the secondary combustion
chamber E, heats the pipes and G to a considerable extent, so that the air
passing through the said pipes from the outside, is brought to a comparatively high
temperature of heat at the time the air reaches the primary combustion chamber.
By having the perforated pipe H, the air passing through the pipe is equally
distributed in the upper part of the primary combustion chainber, so that a uniform
burning of the fuel is insured.
A fire being started in the furnace, the destructive distillation of the fuel in
the fire pot and the evolution of the combustible gases first takes place, then the
said gases being mixed with a quantity of heated air, a portion of the said gases
will be burned and the remainder heated to such temperature that the carbon
therein will have its chemical affinity for oxygen awakened, and then the thus
heated and partially consumed gases being subjected to a further supply of heated
air, the gases and air will be gradually mixed and maintained at a temperature
high enough to support combustion, so that the unburned gases will all be
consumed.
.
It will thus be seen that by the arrangement described, the fuel burning in the
fire box is utilized to the greatest advantage, as a complete combustion of the fiel
takes place owing to the proper supply of air, directly above the fire box 13, and
by a second supply in the top of the primary combustion chamber when coming in
contact with the heated nir supply by the pipe H. For the purpose of burning
some fuels and for some uses, it may be necessary only to use one set of pipes for
supplying hot air, and the construction may be varied accordingly.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:-
1. The combination with a fire pot, of a primary combustion chamber having
means for supplying air thereto and communicating with the fire pot so as to
receive the gases therefrom, a secondary combustion chamber covering or surrounding
the primary combustion chamber and having communication therewith at the top of
the latter through a restricted opening, and means for supplying air to the primary
combustion chamber at said restricted opening, substantially as described.
2. The combination with a fire pot, of a primary combustion chamber above the

page_text: fire pot and having means for supplying heated air thereto at the lower part, a
secondary combustion chamber surrounding the fire pot and primary combustion
chamber, and having communication with the primary combustion chamber at the
top of the latter through a restricted opening, and means for supplying heated air
to the primary combustion chamber at the said restricted opening, substantially as
described.
3. The combination with a fire pot, of an arched primary combustion chainber
above the fire pot and having a valve controlled opening in its top, a casing
surrounding the fire pot and primary combustion chamber and forming a secondary
combustion chamber communicating with the primary combustion chamber through
said valved opening, and pipes leading from the outer air through the secondary
combustion chamber to the upper and lower portious of the primary combustion
chamber, substantially as described.
4. A furnace, comprising a shell, a primary combustion chamber, fire pot, and
ash-pit arranged and spaced from the shell to form a secondary combustion chamber
surrounding the several parts, pipes leading from the lower part of the primary
combustion chamber through the secondary combustion chamber and through the
lower part of the shell, and a chimney connected with the upper part of the primary
combustion chamber by a valved flue, and having its lower end connected with the
secondary combustion chamber, substantially as described.
5. A furnace comprising a shell, a primary combustion chamber, fire box, and
ash-pit arranged in the shell and spaced therefrom to form a secondary combustion
chamber, the top of the primary combustion chamber being provided with an
opening, a valve for closing said opening, pipes leading from the outer air through
the secondary combustion chamber and discharging into the upper and lower
portions of the primary combustion chamber, and a chimney connected with the
primary combustion chamber by a valved flue, and having its lower cud connected
with the secondary combustion chamber, substantially as described.
6. A furnace, comprising a shell, a primary combustion chamber, a fire box, and
ash-pit arranged in the shell and spaced therefrom to form a secondary combustion
chamber, the primary combustion chamber being arched and provided with an
opening in its top, a valve for closing said opening a perforated pipe arranged
longitudinally in the top of the primary combustion chamber, valved pipes leading
from the outer air through the secondary combustion chamber and primary com-
bustion chamber and connected with said perforated pipe, valved pipes leading
from the outer air through the secondary combustion chamber and into the lower
part of the primary combustion chamber, and a chimney connected with the
primary combustion chamber by a valved flue and having its lower end connected
with the secondary combustion chamber under the ash-pit, substantially as herein
shown and described.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.