Improvements in Annealing Furnaces.
Year: 1899

page_text: Date of Application, 30th Mar., 1899-Accepted, 13th May, 1899
COMPLETE SPECIFICATION.
Improvements in Annealing Furnaces.
We, WILLIAM SWINDELL, Engineer, residing at No. 27, Esplanade Street, in the
City of Allegheny, County of Allegheny, State of Pennsylvania, and United States
of America, and JOHN COTTON SWINDELL, Engineer, residing at No. 1500, Federal
Street, in the City of Allegheny aforesaid, 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:-
-
Our invention relates more particularly to furnaces of the class designed to
receive and impart heat to annealing boxes containing sheets, plates, or other articles
which are to be annealed, and its object is to provide a furnace of such class in
which a uniform degree of heat may be imparted to the annealing boxes and an
economical consumption of gaseous fuel be attained.
The improvement claimed is hereinafter fully set forth.
In the accompanying drawings; Figure 1 is a vertical transverse section through
an annealing furnace embodying our invention, taken at the line, w, w, of Fig. 3;
Fig. 2, a longitudinal section through the lower portion of the same, at the line, a,
of Fig. 4; and Figs. 3 and 4, horizontal sections through the same, at the lines y, y,
and z, z, respectively of Fig. 1.
In the practice of our invention, we construct a furnace having an annealing
chamber, 1, which is preferably square or rectangular in horizontal section, above
its floor, 2, and a series of gas and air flues below the floor. The annealing chamber
is enclosed by and between the floor, 2, an arched top or roof 3, side walls, 4, and
end walls, 5, openings 6, closed by doors 7, being formed in one of the end walls,
for the insertion and removal of the annealing boxes and their contents. The
required degree of heat is imparted to the annealing boxes in the chamber 1,
by the combustion of a mixture of gas and heated air, which is supplied to the
chamber through a series of flues, located below the floor, and supply passages
formed in the side walls and connecting therewith, the essential features of which
flues and passages are as follows.
Longitudinal gas supply flues, 8, 8, are formed in the masonry of the lower
portion of the furnace, each of said flues extending throughout the length of the
furnace, below the floor of the annealing chamber and adjacent to one of the side
walls. Pipes 9, 9, lead from a suitable gas producer to the gas supply flues, 8, 8,
the flue on each side of the furnace communicating, at one end, with one of said
pipes, and the supply of gas therefrom being controlled by a suitable valve, 10.
The gas flues 8, communicate with the annealing chamber 1, by a plurality of
vertical gas supply passages, 11, which are formed on the inner sides of the side
walls, 4, and open into the annealing chamber a short distance above the floor.
Two transverse air admission flues 12, 12, (see dotted lines Fig. 3) the outer open
ends of which may be provided with proper valves or doors, extend from the sides
of the furnace towards its centre, below the gas supply flues, 8, and adjacent to
the end of the furnace at which the pipes 9, leading from the producers, are
located. Longitudinal air supply and heating flues, 13, communicate at one end
with the air admission flues, 12, as shown in Fig. 1, and lead therefrom to or

page_text: nearly to the opposite end of the furnace, where they communicate, through
ports 13, with superposed longitudinal air supply and heating flues 14. The
Hues 14 communicate, through ducts 14, with a plurality of vertical air supply
passages, 15, which are formed on the inner sides of the side walls, 4, each being
located adjacent to one of the gas supply passages 11, and opening into the anneal-
ing chamber on, or nearly on, a level therewith.
A central waste or discharge flue, 16, extends longitudinally through the
furnace, below the floor, and communicates with the annealing chamber by a
plurality of discharge passages, 17. The flue. 16 is connected, at one end, by
transverse passages or connecting flues, 18, with two lateral waste or discharge
flues 19. which extend through the furnace, and, passing out of the opposite end
thereof, are led into a common stack 20. Each of the flues 19 is provided with a
damper 21, governing communication with the stack 20.
The air supply and waste flues are so located; relatively one to the other, that
the heat of the products of combustion passing from the annealing chamber to the
stack 20 shall be imparted as fully as possible to the currents of air passing to
the annealing chamber through the flues 13 and 14. To this end, a flue, 13, is
located on each side of the central waste flue, 16, and on each side of each of the
lateral waste flues 19. The air flues, 14 are each located immediately above one of
the lateral waste flues 19, and immediately under and in contact with the floor of
the combustion chamber, so that they are effectively heated. The walls separating
the waste and air flues are made, as thin as is consistent with stability, of con-
struction, and it will be seen that the lateral waste flues, 19, are each surrounded
on three sides by air flues, and that there are air flues on two opposite sides of the
central waste flue, 16.
Access to the gas flues, 8, is afforded by openings, 22, controlled by 'doors, 23,
and the air flues may also be provided with suitable openings and doors.
While the most effective results are attainable by a duplicate system of air,
gas and waste flues, on opposite sides of the longitudinal central plane of the
furnace, as above described, it will be obvious that such duplication is not an
essential of our invention, and that the same structural and operative principle
would be embodied in a furnace. of a construction substantially similar to that of
one half of the furnace shown.
:
In the operation of the furnace, gas from the producer passes from the pipes.9,
into the flues 8, and thence into the annealing chamber 1, by the passages 11,
which distribute it throughout the length of the chamber. Air enters at the open
ends of the admission flues 12, and thence passes, in divided currents, through the
flues, 13, from which it passes through the flues 14, and is thence distributed
throughout the length of the chamber by the passages 15, each of which is in
close proximity to a gas passage 11. The gas and air meet and are mingled at the
outlets of the passages 15 and 11, and the mixture is ignited and burns thereat,
the heat evolved being exerted, with substantial uniformity, throughout the
annealing chamber.
The hot products of combustion pass from the annealing chamber, by the dis-
charge passages, 17, into the waste flue 16, and thence pass through the 'connecting
flues 18, and lateral flues, 19, to the stack, 20. In their passage through the
flues 16 and 19, their heat is imparted to the walls thereof, and thence to the
currents of air passing through the flues 13, and 14, to the annealing chamber.
The heat of the waste gases is thus effectually utilized before their escape into the
stack.
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. In a furnace, the combination of a combustion chamber, a gas supply flue
extending longitudinally below the floor thereof, a plurality of gas supply passages
leading from the gas supply flue into the combustion chamber, an air supply flue,

page_text: extending longitudinally below and in contact with the floor of the combustion
chamber, so as to be heated thereby, a plurality of air supply passages leading
from the air supply flue into the combustion chamber, and a waste flue leading out
of and extending below the floor of the combustion chamber and adjoining the air
supply flue.
2. In a furnace, the combination of a combustion chamber, a gas supply flue
extending longitudinally below the floor thereof, whereby it is heated, a plurality
of gas supply passages leading from the gas supply Hue into the combustion
chamber, a waste flue leading out of and extending below the floor of the com-
bustion chamber, air supply flues extending longitudinally below and in contact
with the floor of the combustion chamber, whereby they are heated, and adjoining
opposite sides of the waste flue, whereby they are further heated, and a plurality
of air supply passages leading from the air supply flues into the combustion
chamber.
3. In a furnace, the combination of a combustion chamber, a gas supply flue, a
plurality of gas supply passages leading from the gas supply flue into the com-
bustion chamber, a waste flue leading out of and extending below the floor of the
combustion chamber, air supply flues extending longitudinally below the floor of
the combustion chamber, and adjoining opposite sides of the waste flue, an air
supply flue, in contact with the floor of the combustion chamber, whereby
it is heated, and communicating at one end with said air supply flues and adjoining
a third side of the waste flue, and a plurality of air supply passages leading there-
from into the combustion chamber, each adjacent to the outlet of one of the gas
supply passages.
4. In a furnace, the combination of a combustion chamber, gas supply flues
extending below, the floor and adjacent to opposite sides thereof, a plurality
of gas supply passages leading from the gas supply flues into the combustion
chamber, a central waste flue leading out of and extending below the floor of
the combustion chamber, lateral waste flues, each leading independently from the
central waste flue, air supply flues extending longitudinally below the Hoor of the
combustion chamber and adjoining opposite sides of the central and lateral waste
flues, and a plurality of air supply passages leading from the air supply flues into
the combustion chamber, each adjacent to the outlet of one of the gas supply
passages.
Dated at Pittsburgh, Pennsylvania, U.S.A.. this Eleventh day of March.