Improvements in Metallurgical Furnaces.
Year: 1892

page_text: Date of Application, 11th Oct., 1892-Accepted, 3rd Dec., 1892
COMPLETE SPECIFICATION.
Improvements in Metallurgical Furnaces.
I JOHN NICHOLAS LAUTH of 2332 S 12th Street in the City of St. Louis, in
the State of Missouri, one of the United States of North America Iron Manu-
facturer, 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 reference being had to the accompanying drawings,
forming part of this Specification:
--
My invention relates to certain new and useful improvements in metallurgical
furnaces for heating and puddling iron or steel.
The object of my invention is to provide a furnace which will be effective in
operation and at the same time heat the billets to the desired temperature with the
smallest amount of fuel and to this end I construct the melting or heating hearth
of the furnace inclined downward toward the stack as is usual in this class of
furnaces and in having the roof of said furnace inclined upward from the front of
the fire chamber toward the neck or stack of the furnace so that the products
of combustion will strike against the wall above the outlet of the furnace and be
reverberated or directed back onto the metal to be heated or melted on the hearth
while at the same time the carbonic acid gas together with the slag is allowed to
pass to the bottom of the stack.
Heretofore in the construction of furnaces of this class it has been the prevailing
method to provide a roof or arch over the melting chamber inclining downward
and to the stack end of the furnace and by this construction of roof the drawing
off of the products of combustion before the same are thoroughly united with air
and deprived of their heat units, it is practically the result accomplished so that
the percentage of the heat actually utilized is but a small portion of that which
goes up the stack.
This is due mainly to the fact that the flame coming from the fire chamber is so
dense as to be only partially combusted by reason of being and not permitted to
be thoroughly intermixed with air which even though injected into the fire
chamber, is in a great measure carried along in the dense flame without being
taken up or united before entering the stack.
As the main essential to the perfect combustion of fuel is thorough intermingling
of the oxygen of the air therewith it has been my purpose to provide not only for
the expansion of the flame whereby it will take up a greater percentage of air, but
for the confining and retention of the flame and its attendant gases within the
melting chamber, so that time which is essential for this thorough mixing with the
air, may be given and the gases combusted before entering the stack.
My invention consists in constructing a furnace for metallurgical operations
with a fire chamber, hearth and interposed bridge wall of usual or suitable con-
struction and with a rear deflecting wall, an exit to the stack below the deflecting
wall and a roof inclined upward from the front wall of the fire chamber to the
rear deflecting wall substantially as herein described whereby the gases of com-
bustion and partially commingled air are carried freely over the bridge and through
a combustion chamber of constantly increasing area to the rear of the furnace and
by contact with the rear deflecting wall are returned and more thoroughly com-
mingled and the inflamable gases consumed before passing to the stack.
In the accompanying drawing I have illustrated the invention as applied to a
heating furnace for purposes of heating and welding metal.
In all other respects other than the inclination of the roof A, the furnace does
not differ essentially from other well known forms of this type, it being usual to
have the bridge B, to partially divide the fire chamber C, from the melting

page_text: chamber D, and also to locate the neck E, forming the entrance into the stack F,
at the sloping end of the hearth G.
At the stack end of the furnace a wall H is formed instead of the usual arch
which instead of choking the flame and facilitating its withdrawal from the
chamber D, presents a barrier for deflecting back the expanded flame and gases
which are further combusted by meeting the heated flame coming directly over the
bridge wall from the fire chamber.
It is obvious that the wall H may be concave if found convenient, as illustrated,
by the dotted lines, as by that means the deflecting action of the same may be
better accomplished.
By inclining the arch or roof as shown and described so that the flame will strike
the rear wall and be deflected back onto the metal to be heated, a complete com-
bustion is effected and a saving of at least twenty five (25) per cent. of the fuel.
The flame produced by this reverberatory action is a non-oxidising flame thus
saving in the waste of metal from three and one half to six per cent. over the old
method of heating.
The action of the furnace briefly described is as follows:-
The air blast K located under the grate of the fire chamber ejects air into the
burning fuel to make the combustion as rapid as possible as is usual where this
device is employed but the flame which comes over the bridge dividing the fire-
chamber from the melting or heating chamber is of such density that much of the
air is carried along without being intimately mixed.
By the gradually increasing size of the melting chamber, the flame is allowed to
increase its volume thereby uniting with the air more completely and at the same
time being carried along to the stack end of the furnace as indicated by the arrows
near the roof where it is deflected back by the wall H.
The return gases having had more space for expansion and more time for mixing
with the air are met by the flame direct from the fire chamber and combusted.
The carbonic acid gas which is generated and which is necessarily a present
element is carried off first by virtue of its density thus leaving the flame and
gases which are deflected back on the articles to be melted of a non-oxidizing
nature.
The action therefore of the flame and gases is such as to be very thoroughly
utilized in the melting chamber before being taken up the stack it being understood
that the expansion of the flame and gases as well as the time they are retained
within the furnace act to make them more readily combustible before they leave
the melting chamber.
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
A furnace for metallurgical operations constructed as herein described with a
fire-chamber, a hearth for the metal, a bridge wall interposed between the fire
chamber and the hearth a deflecting wall at the rear an exit to the stack below the
rear deflecting wall and a roof inclined upward from the front wall of the fire
chamber to the rear deflecting wall whereby the gases of combustion are carried
freely over the bridge and through a combustion chamber of constantly increased
area to the rear of the furnace and by contact with the rear deflecting wall are
returned and more thoroughly mingled with the air and consumed before passing
to the stack as explained.
Dated this 11th day of October 1892.
WHITE & WOODINGTON,
27, Southampton Buildings, London, Agents.