Improvements in mume Furnaces.
Year: 1897

page_text: Improvements in mume Furnaces.
We, EMILIO DAMOUR, Mining Engineer, of 60, Boulevard St. Michel, Paris,
and ERNEST ADNET, Builder, of 26, Rue Vauquelin, Paris, in the Republic of
France, do hereby declare the nature of this invention to be as follows:-
The object of our invention is to obtain a high degree of temperature as well as
an economy of fuel in muffle-furnaces.
As is well known a muffle furnace is a furnace in which the material that is to be
heated is not brought into direct contact with the flame. Our invention relates to
muffle-furnaces of all kinds and sizes whether for laboratory purposes or for
industrial operations; it allows of economically heating several muffles at a time,
any kind of fuel being used in the furnace.
We attain the aforesaid advantages by the following means, viz.-
1. The wasto heat still contained in the burnt gases or smoke after they have
heated the muille (or the muffles) is recovered by a suitable regenerating apparatus
(such as brick chambers, iron or clay pipes and the like) owing to which the air
or the combustible gas, or both, are heated before being allowed to burn.
2. The flames, whatever may be the nature of the fuel employed, are ourved by
a transverse partition, parallel with the side of the muffle, the object of this partition
being to direct the hottest part of the flame against and all around the muffle, and
finally below it.
Owing to this partition the flames do not cross the whole fire place as they do in
most industrial furnaces, and the burnt gases may be allowed to escape on the same
side where the gas is admitted; the gas and air entrance pipes, or the fire grates
may be placed on both sides of the muffle in a symmetrical order. The flames on
each side of the furnace being curved near the top of the muffle where they first
meet, then turn around the muffle, and generally meet again underneath it, in the
middle of the furnace, before entering a compartment or the regenerating apparatus.
The heat is thus symmetrically distributed, tho inside temperature of the muffle is
equalized, and the course taken by the flame is lengthened, which is very
advantageous especially in small muffle furnaces.
3. The thickness or conductibility of the above described partition must be inter-
mediate between the thickness and conductibility of the sides of the muffle and those
of the exterior wall of the furnace so as to concentrate most of the heat in the
muffle.
In a furnace having two muffles, for example, placed one above the other the
lower one is heated by the waste heat in the burnt gases or flames after heating the
upper one.
The gas being admitted into the fire place through the pipes on both sides of the
furnace and meeting the hot air coming from the regenerating apparatus takes the
form of a long flame which is curved by the partition passes under the muffle and
escapes through a longitudinal opening in the middle of the upper fire place. This
opening is situated exactly over the top of the lower muffle so that the Hames being
again divided pass all round the second muffle and finally escape under its floor or
sole, and thence pass to the regenerating apparatus below.

page_text: The regenerating apparatus which is advantageously placed under the two muffles
is made with iron pipes surrounded with the smoke boxes in such a way that the
air passes to the fire place in a contrary direction to the smoke in order to obtain a
progressive and methodical heating.
The circulation of both the gases and the air in the fire places and regenerating :
apparatus is effected by means of a good chimney or by artificial draught.
Dated this 30th day of March 1807
Improvements in Muffle Furnaces.
We, EMILIO DAMOUR, Mining Engineer, of 60, Boulevard St. Michel, Paris,
and ERNEST ADNET, Builder, of 26, Rue Vauquelin, Paris, in the Republic of
France, 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 to muffle furnaces whereby we economically obtain very
high temperatures with great regularity of heat and complete combustion.
Our muffle furnaces are essentially characterized by the following points.
1. The application of the recuperation to the heating of muffles for obtaining a
high temperature.
2. The symmetrical arrangement of the burners and of the heating in general
with relation to the muffle in order to afford regularity of heating.
3. The employment of a reverberatory arch necessitated by this symmetrical
heating and designed to elongate the flame in order to obtain complete combustion
even in a furnace of small dimensions.
4. The construction of the furnace with a decreasing thickness, or an increasing
conductibility, of the arches from the exterior towards the interior in order to con-
centrate the heat in the muffle.
In the accompanying drawing we have represented by way of example a laboratory
muffle furnace constructed according to our invention.
Figure 1 is a longitudinal section of the furnace;
Figure 2 is a horizontal section on the line 1-2 of Figure 1;
Figure 3 is a horizontal section on the line 3-4-5-6-7-8 of Figure 1.
Our muffle furnace is constructed with several compartments, the lowermost of
which serves as the base or support and the next upper one, of a semi-cylindrical
arch shape, constituting the fire place or furnace proper.
The lowermost floor A is divided in the direction of its length by baffle-plates
or partitions a extending from opposite sides of the furnace. Two similar tubes b
and of sheet or cast iron, refractory clay or other suitable material, extending from
one side to the exterior are arranged in serpentine fashion between the baffle-
plates and are continued by inclined tubes which extend above the horizontal
partition and below the fire place into the two recuperating chambers BB of the
floor above.
C
In the tubes b and circulates the air serving to feed the fire as horeinafter
described and around the said tubes the hot and burnt gases on their way from the
fire to the chimney circulate from the centre towards the ends.
The second floor of the furnaces comprises a muffle d arranged in the middle of the
furnace and surrounded at a certain distance by curved partitions e, e concentric
with the said muffle and supported by short tubes of refractory clay above the floor c. 5

page_text: The uppermost floor or compartment encloses a muffle d also placed in the muddle
of the furnace, a concentric partition for the reverberation of the flame and the
arched casingh of the furnace which is, itself, covered by a casing j of masonry or
other suitable non-conducting material and by an outer metal jacket i.
In the arrangement shown in the drawing, the gaseous or liquid fuel is intro-
duced through two horizontal tubes and and passes through the
burners 1,1,1,,, into the furnace at C above the uppermost partition m.
Opposite each fuel inlet the said partition is provided with a vertical hole n
which forms a communication between the furnace and the hot air or burning gas
regenerating chamber B.
The body to be heated being placed in the muffles d and d¹ the jets of the various
burners are lighted; the smoke and gases from the furnace pass between the arch h
and the partition g are driven downwards on arriving at the upper part of the
furnace and circulates between the said partition g and the muffle d. The two
currents of hot gases unite beneath the muffle, descend vertically through a
passage o and thus reach and pass around the lower muffled after having com-
pletely heated the upper one. They heat the lower muffle, escape through the
aperture o made in the horizontal partition c and pass from the centre towards the
ends into the compartment A. between the baffle plates and around the tubes b
and in such a manner as to yield the heat they have retained to the cold gases
passing through the said tubes; this exchange is effected by transmission, through
the metal or other walls of the lubes b and b¹.
The result is that the heat which escapes from the fire pluce without having been
absorbed by the muffles is regenerated by the gases serving to feed the furnaces.
Consequently very high temperatures can be obtained as compared with ordinary
furnaces with the same consumption of fuel or a great economy of fuel with the same
degree of temperature.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is :
-
1. A muffle furnace characterized by the recuperation of the heat of the gases on
their way to the chimney and by utilizing the said heat for heating the gases
serving for the combustion with the object of obtaining a high temperature in the
heating of the muffles by the symmetrical arrangement of the heating with relation
to the muffle to afford regularity of heating; by the employment of a reverberatory
arch designed to elongate the Hame to cause complete combustion and by the con-
struction of the furnace with a decreasing thickness, or an increasing conductibility,
of the arches from the exterior towards the interior for concentrating the heat in
the muffle, substantially as set forth.
2. A muffle furnace of the kind claimed in the first claiming clause having three
floors viz-The lower floor divided longitudinally by partitions or baffle plates
between which tubes b, 61 are arranged in serpentine fashion, in which tubes
circulate the air serving to feed the fire and around which tubes circulate the gases
from the furnace on their way to the chimney; the second floor comprising a
muffle a arranged in the middle of the apparatus and surrounded at a certain
distance by curved partitions c, c concentric with the muffle; the upper floor con-
taining a neuffle d' also placed in the middle of the furnace; a concentric partition g
having an aperture at its upper part for directing the flamo of the furnace down-
wards before it enters the central chamber, and a covering arch for the furnace
arranged concentrically with the partition g, substantially as set forth.
D
L
DO
n
1005
G. F. REDFERN & Co.,
4, South Street, Finsbury, Loudon, Agents for the Applicants.