Improvements relating to Gas Furnaces.
Year: 1891

page_text: Date of Application, 31st Jan., 1891
Complete Specification Left, 23rd Oct., 1891-Accepted, 28th Nov., 1891
PROVISIONAL SPECIFICATION.
Improvements relating to Gas Furnaces.
I, RICHARD NICKERSON OAKMAN the younger, of Greenfield in the State of
Massachusetts, United States of America, Gentleman, do hereby declare the nature
of this invention to be as follows :-
This invention relates to furnaces for melting metals which are heated by means
of a combination of gas and air under pressure, and the invention consists in so
constructing the furnace and accessories, that the action will be continuous in one
direction, that is to say, it will not be necessary to reverse the current of air and
gas from time to time, as heretofore, and the products will be utilized to heat the
air required to produce combustion.
The gas employed may be either water gas or producer gas, the nature of both
of which is now well understood.
In carrying out this invention, the open hearth furnace is made circular, with the
usual door etc.
The air and gas are conveyed to points over the furnace, from which they pass,
by tubes, to the nozzles or burners, which are arranged in the wall of the furnace,
and these tubes may be provided with suitable valves.
In this manner, the pressure is equal at all the burners.
These burners are placed near the top of the furnace, and are set at a slight
angle to the radial lines, that is to say, tangential to a circle having as its centre
the vertical axis of the furnace and a diameter varying according to the diameter
of the furnace, and the gas and air are directed across the furnace.
The object of this arrangement of the burners is to give such motion to the air
and gases as to ensure a perfect admixture, and produce proper combustion, without
giving such an amount of motion as will disturb the bath.
The burner consists of a tubular air nozzle with a conical end, and a lateral inlet
for the air, and a pipe for gas arranged internally of, and concentric with this
tube, the end of the pipe being provided with an adjustable conical valve, which
serves the two-fold purpose of a regulator to regulate the supply, and a deflector
to deflect the issuing gas into the current of air, to cause a mixture of the gas
and air.
The waste products pass by means of a flue, arranged in the side of the furnace,
just above the hearth and below the burners, to a chamber which serves as an air
heater, and thence pass away by a chimney, or they may be made to pass direct to
the chimney, without passing to the heater.
This chamber contains a series of tubes which pass through the end walls, and
are supported on bars in the end walls of the chamber. The tubes are formed with
square or octagonal flanges, and are connected outside the walls with suitable bends
having similar flanges clamped on or otherwise secured so as to produce a continuous
passage for the air, and these bends are covered at either end of the chamber by
an iron plate or door secured to the walls in any convenient manner.
The cold air enters at the highest and coolest part, and passes downwards, gradually
becoming hotter as it descends. The waste products, as they leave the flue, strike
against a deflecting arch suitably arranged for the purpose, so that the hot gases
may not burn and destroy the lower tubes.
The outlet for the waste gases will also serve as an outlet for the slag, the floor
of the chamber being inclined to serve as a slag hearth and spout.
A cold air inlet may be provided to the furnace, to be used when the heater is
not employed.

page_text: The gas and air burn in the upper part of the furnace, and the heat is radiated
downwards onto the metal.
It will be evident that a similar arrangement of furnace may be used for smelting
سم
NEWTON & SON,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements relating to Gas Furnaces.
I RICHARD NICKERSON OAKMAN, the younger, of Greenfield in the State of
Massachusetts United States of America, Gentleman, 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 certain improvements in furnaces for melting and
heating metals, glass, and other materials, by means of gas and air under pressure,
whereby perfect combustion of the gaseous fuel employed takes place, and the
flame evolved therefrom is caused to act in a downward direction, and on the
surface of the molten material under treatment, thereby economizing time and fuel
in the heating operations, and at the same time protecting the roof of the furnace
from excessive heat.
In carrying out this invention, the furnace, say, an open hearth furnace, is made
circular, with the usual doors, etc., and with a solid crown or roof, and means are
provided. for introducing a blast of heated air and gas at one or more points in the
side walls of the furnace, at some distance below the roof, and tangential to
the vertical axis of the furnace, and one or more gas outlet flues are placed in the
side walls of the furnace, at about the level of the hearth or molten bath. These
outlet flues may be radial to the vertical axis of the furnace, or preferably
tangential to the surface of a cylinder or other curved surface having the same axis
as the furnace.
The furnace being arched over from side to side with a solid crown or roof, and
of a height sufficient, the peculiar arrangement of air and gas inlets and gas outlets
above referred to will prevent any injury to which it is ordinarily liable in
maintaining the requisite high degree of heat within the furnace. Means are also
provided for utilizing the heat of the outgoing waste products of combustion, to heat
the air supplied to the furnace for the combustion of the gaseous fuel, and the air
pipes are arranged in such a manner as to prevent explosions from gas working
back into the air pipes.
In the accompanying drawings:-
:-
Fig. 1 is a central vertical section through the furnace and air heater.
Fig. 2 is a horizontal section taken on the line of Fig. 1.
Fig. 3 is a central vertical section at right angles to Fig. 1.
Fig. 4 is a horizontal section on the line y y, Fig. 1.
Fig. 5 shows in section an arrangement of burner it is preferred to employ.
The letter A represents the furnace, the body of which is preferably made
cylindrical, or of other curved form, and is provided with a hearth B lined with a
suitable refractory material, and in which the metal is melted. The hearth may, if
desired, he kept cool by any of the means usually employed for such purposes.
The furnace is also provided with a tap hole or spout p, and with the usual working
doors 0, which are closed by well known means. The crown or roof A' is arched
from side to side, and is built up solidly without any opening therein, and of
sufficient height above the tuyere openings, to prevent any injurious action resulting
from the high temperature maintained within the furnace, as will appear more fully
hereinafter.
At some distance below the roof A' and above the doors o, and inserted through

page_text: the walls of the furnace, are the tuyeres c, shown in the drawings as four in number,
disposed at equidistant points about the furnace, and placed so that their axes are
tangential to the surface of a cylinder or other surface having the same vertical
axis as the furnace. They may be slightly inclined downward, though I do not
limit myself to such construction. The tuyeres are so placed that the flame
issuing therefrom will cut across the furnace to a point on the wall in front of the
next burner, so that the first circle described by the burning gases is about half
the diameter of the furnace, and the flame and products of combustion are given a
whirling or gyratory motion around the combustion chamber above the materials
on the hearth. Below the tuyeres, and ou about a level with the plane of the
upper surface of the hearth, are located the flues a, serving as outlets for the
products of combustion. These outlet flues are either perpendicular to the plane
of the movement of the gases, or preferably bear the same relation to the walls of
the furnace as do the tuyeres c, that is, their axes are tangential to a cylinder
having the same axis as the furnace chamber. This tangential disposition of the
outlet flues assists to retard the escape of the gases, as the gases in their whirling
motion about the combustion chamber are deflected by the walls of the furnace,
and do not find as ready an escape as when the outlet is arranged perpendicularly
to the plane of their movement. The gases are thus held in the combustion
chamber for a longer period of time, their combustion is ensured, and their heat
utilized effectively.
The heat restoring chamber d is preferably made independent of the furnace,
and is supported on iron posts and beams just above the roof of the furnace, though
this is not essential, as it may be located elsewhere in proximity to the furnace.
The chamber is provided with partitions, extending alternately from the top and
bottom, for causing the current of hot products to circulate back and forth through
the compartments, and thus better heat the air pipes. The escape flues a connect
with the uptakes b, as shown in Fig. 2, and these uptakes connect with the upper
part of the heat-restoring chamber d. A flue N, provided with a damper n, leads
from the lower end of the chamber d, and conducts the waste gases to the chimney
or stack. The damper n controls the outflow of gaseous products, and retains the
flames and products under pressure in the furnace. The air to be heated is supplied
through a valve-controlled pipe m, which is connected to a series of connected iron
pipes e and clay retorts or pipes f. The air, in traversing the pipes, is highly
heated by the gaseous products passing through chamber d, and is discharged in
its highly heated condition through flue g, Fig. 2. The flue g connects with an
annular brick flue / below the floor level, from which pipes k, provided with suitable
valves, lead to the burners, so that the air is kept at a high heat, without much loss
by radiation, to the point of ignition. This piping from below prevents all risk of
explosions due to the gas working back into the air pipes. The gas is admitted to
the burners through pipes t. In operation, the furnace hearth or tank is supplied
with material to be heated or melted, and is properly closed; the gas and hot air
are supplied under pressure to the burners c, and ignited. The relative proportions
of gas and air entering the burners are readily controlled, so as to produce either an
oxidising, a reducing, or a neutral flame, as required. I preferably use water gas
(but a mixture of water gas and producer gas, or producer gas alone, may be used
or burned), and preferably supply hot air, as before explained, to the burners.
The flames are driven tangentially as above described, and are thus given a
gyratory or whirling motion around the combustion chamber. Owing to the
location of the outlet flues near the surface, and but a short distance above the
molten bath, and to the further fact of their direction being tangential to a curved
surface having the same axis as the furnace walls, the flame is propelled towards
the hearth, and will extend downward toward the bath, spreading out over its entire
surface, and passing off at or near the level of the "forehearth." The flame is thus
directed to the point upon which it is desired to concentrate the greatest heat, and
perfect combustion of the gases is effected. There being less current in the top of the
furnace under the roof, the heat will be less intense there than at the sides, and the

page_text: roof will be in a great measure protected from the action of flames. The peculiar
position of the gas-outlet flues serves also as a protection to the roof, as the
vaporised fluxes are prevented from attacking it.
The gaseous products of combustion pass out through flues to the chamber d;
thence, by way of flue N, to the chimney or stack. The air passing through pipes e
and is highly heated by the outgoing gases, and in its heated condition is supplied
to the burners through pipes g, h, and . The flue N may be partially closed by
the damper n, for holding the flame and hot gaseous products under pressure within
the combustion chamber, so that the heat is better utilised, and also that the
external air may not enter and injure the metal or other material when the working
door is open.
The burner consists of a tubular air nozzles, with a conical end, with which
the air pipe is connected, and a pipe for gas arranged internally of, and
concentric with, this tube, and connected with gas pipe t, the end of the pipe
being provided with an adjustable conical valve u', which serves the two-fold
purpose of a regulator to regulate the supply, and a deflector to deflect the issuing
gas into the current of air, to cause a complete mixture of the gas and air.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. In combination with a furnace, the tangential burners and ports arranged in
the circumferential wall, and the escape flue leading from the furnace and below
the burners, substantially as described.
2. In combination with a furnace, the tangential burners and ports arranged in
the circumferential wall, and the tangential escape flue leading from the furnace
below the burners, substantially as described.
3. In combination with a furnace provided with burners, the gas escape flue
leading from the furnace, on or about a level with the plane of the upper surface
of the hearth, substantially as described.
4. In combination with the furnace and its
chamber provided with air-heating pipes, and
substantially as described.
Dated this 23rd day of October 1891.
escape flue, the heat-restoring
having a controlling damper,
NEWTON & SON,
Agent's for the Applicant.