Improvements in Furnaces.
Year: 1899

page_text: Improvements in Furnaces.
I, JOSEPH EMERSON DOWSON, M. Inst. C.E., of 39, Old Queen Street, Westminster,
in the County of London, do hereby declare the nature of this invention to be as
follows:-
In many manufacturing processes it is necessary to heat certain materials
gradually, then to heat them highly, and finally to cool them gradually. For
instance in the baking and glazing of bricks, tiles and pottery ware, in the baking
of porcelain, and china, in annealing wire and metal castings, in the heating of
iron castings to make them malleable, it is usual to place the materials to be heated
in a kiln or oven, or in a muffle which is cold. The kiln or oven, or the muffle
is then heated and afterwards cooled.
In my invention I pass such materials as are above described through a furnace
or chamber of which part is heated continuously. The heat diminishes towards
the charging end of the said furnace and the materials are thus gradually heated
as they approach the hottest part of the said furnace. At the other end of the
highly heated part of the said furnace there is an extension which serves as a
cooling chamber in which the materials which have passed through the highly
heated part can be allowed to gradually cool.
The said furnace can be heated by any suitable combustible gas, which can be
admitted through suitable pipes or ducts. Where high temperatures are required,
it is desirable to heat the air for combustion of the gas by heat derived from the
outgoing products of combustion. For this purpose separate flues for air and
products of combustion can be built in the sides along the top, or near the lower
part of the said furnace.
Another way is to let the air for combustion of the gas be drawn through the
cooling chamber, so that it may be heated by coming in contact with the materials
or their containers in the said cooling chamber. It also follows that in this way
the cooling of the said materials can be quickened, if desirable, and if contact of
the air with the heated materials or their containers will not be injurious.
By use of suitable pipes or ducts, for the admission of gas and suitable valves
or cocks the greatest heat can be produced where required that is to say brought
nearer to the charging end or to the discharging end as varieties of materials
treated may require. This correspondingly alters the relation between the length
of the heating up and cooling down portions of the said furnace. The rate of
fall of temperature in the direction of the charging end can also be regulated.
The admission of air can be regulated by dampers or other suitable con-
trivances.
For convenience of passage through the said furnace the material to be heated
may be placed on trucks or other suitable carriers on wheels or rollers. If the
materials to be heated must be in pots, boxes or muffles, the pots boxes or muffles
can be placed on the said trucks or carriers. It is best to keep the furnace full
of the said trucks or carriers, and if preferred the furnace can be built on an
incline to facilitate their passage from end to end.

page_text: In cases where the greatest heat required in the said furnace will not injure
the said trucks or carriers, there will be no need to protect them specially. Where
the temperature of the said furnace must be high, the ironwork used for the
said trucks or carriers should be protected by constructing the floor of the said
trucks or carriers of firebricks or if the floor is of metal by covering it with
firebricks. If desired the said floor can also be made to project laterally over
dwarf walls in the furnace to further screen the ironwork below the said floor.
The iron work under the floor of the said trucks or carriers can also be cooled
by a current of air admitted at one or both ends of the said furnace.
Dated this 7th day of January 1899.
HERBERT HADDAN & Co.,
Agents to Applicant,
18, Buckingham Street, Strand, W.C., London.
I, JOSEPHI EMERSON DOWSON, of 39, Old Queen Street, Westminster, in the
County of London, M. Inst. C.E., 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:-
In many manufacturing processes it is necessary to heat certain materials
gradually, then to heat them highly, and finally to cool them gradually, as in the
baking and glazing of bricks, tiles and pottery ware, in the baking of porcelain
and china, in annealing and enamelling hollow ware, and in annealing wire and
metal castings. For instance in the heating of iron castings to make them malle-
able it is usual to place the materials to be heated in a kiln or oven, or in a muffle
which is cold or nearly cold, at starting and this kiln, oven or muffle is then
heated and afterwards cooled before the materials are removed. In the case of
hollow-ware, the castings when cold are put into pans or receivers, and these are
put into muffles or ovens to be highly heated, and are afterwards withdrawn to be
cooled.
In my invention I pass the materials to be heated through an elongated furnace
or chamber, in part of which heat is produced continuously, while the two ends
are at a lower temperature than the middle portion thereof.
In the accompanying drawings Figs. 1, 2 and 3 represent the cross section,
longitudinal section and sectional plan respectively of one arrangement of the said
furnace, while Figs. 4, 5 and 6 represent similar views of another arrangement
thereof; Figs. 1 and 4 being drawn to a larger scale than the remaining figures.
In both these arrangements the materials to be heated are caused to enter at
one end a of the furnace, and to leave at the other end . The furnace is heated
by any suitable combustible gas, which can be admitted and controlled by valves
at c, c or other points desired. In this way the greatest heat will be where the
gas burns, and the heat will gradually diminish towards the end a, near to which
the spent gases have outlet from the furnace; there will also be less heat towards
the end than in the part where the gas burns. The materials to be heated are
thus heated gradually after entering the furnace at a, and become more and more
heated as they approach the hottest part where the gas burns.
After passing
through the hottest part of the furnace they become less and less hot as they
approach the discharging end b. The total length of the furnace, the proportion
of it which is to be highly heated, and the exact position and length of the
highly heated portion, will necessarily depend somewhat on the nature of the
materials to be dealt with, the length of time they are to be subjected to heat,

page_text: and the temperature to which they are to be subjected. The proportions shown on
the accompanying drawings will serve as a basis, the essential features being that
the heating of the furnace is continuous, that the temperature can be regulated,
and that the charging and discharging ends are at a lower temperature than the
middle portion thereof.
In the arrangement shown in Figs. 1, 2 and 3 on each side of the furnace
there is a products flue e, air flue f, and gas flue g. The hot products of combustion
leave the furnace and enter the flues e e near the end a and finally escape through
the chimneys or other suitable outlets. The air for combustion of the gas
also enters the flues ff at or near the end a, and in this way it is heated by the
escaping products of combustion before it meets the gas. The gas may enter
flues g g near the end, or it may go direct from the valves c c to the part of the
furnace where it is to burn as shown in Fig. 3. If preferred flues for a like
purpose can be constructed along the top, or the lower part of said furnace.
In the arrangement shown in Figs. 4, 5 and 6 there are no flues as above
described. The gas passes direct from the valve c c to the furnace, and the air
for its combustion enters at the end band becomes heated before it meets the
gas, by coming in contact with the heated materials, or their containers, which
have passed through the hottest part of the furnace. The products of combustion
escape through chimneys or flues m m near the end a as shown in Figs. 5 and 6.
This method of introducing the air quickens the cooling of the said materials, and
is an advantage if the more rapid cooling of the materials is not injurious, and if
contact of the air with the heated materials or their containers is not injurious.
The admission of air can be regulated by dampers or other suitable contrivances.
For convenience of passage through the said furnace the materials to be
heated should be placed on trucks or other suitable carriers on wheels or rollers.
If the materials to be heated must be in pots, boxes or muffles the pot boxes or
muffles can be placed on the said trucks or carriers as shown in the accompanying
drawings. If preferred there can be two or more rows of trucks or carriers in
the part near the discharging end b, so that the materials may have a longer time
in which to be cooled gradually before they are discharged at the end b. It is best
to keep the furnace full of the said trucks or carriers, and if preferred the furnace
can be built on an incline to facilitate their passage from end to end. At each
end of the furnace there can be a turntable or cross tramway k to facilitate the
charging and discharging.
In cases where the greatest heat required in the said furnace will not injure
the trucks or carriers, there will be no need to protect them specially. Where
the temperature of the said furnace must be high, the ironwork used for the said
trucks or carriers should be protected by constructing or covering the floor of the
said trucks or carriers of or with firebricks, or if the said floor must be highly
heated it should have firebricks under it to protect the ironwork which is under-
neath. If desired the said floor can also be made to project laterally over a
dwarf wall on each side of the furnace, to further screen the ironwork below the
said floor, as shown in Figs. 1 and 4. In these figs. the floor h of the truck has
firebrick work under it to protect the ironwork which is underneath, and there is a
dwarf wall i on each side of the furnace.
If desired the ironwork under the floor of the said trucks or carriers can also
be cooled, to a certain extent, by a current of air admitted at or near one or both
ends of the said furnace.
Having now particularly described and ascertained the nature of my invention
and in what manner the same is to be performed I declare that what I claim is:-
1. In a furnace the construction of the furnace chamber substantially as
herein indicated, so that goods may be passed intermittently or continuously in
succession there through, the heat being applied to the furnace at or near the
middle part thereof, so that the heat is greatest at or near the said part and
diminishes towards the ends of the furnace chamber where the goods are respec-
tively admitted and discharged.

page_text: 2. In a furnace the construction of the furnace chamber substantially as herein
indicated so that the goods may be passed intermittently or continuously in
succession therethrough, the heat being applied to the furnace by combustion of
gas at or near the middle part thereof, so that the heat is greatest at or near
the said part and diminishes towards the ends of the furnace chamber where the
goods respectively admitted and discharged; the burning gas and the products of
combustion travelling towards the inlet end of said furnace chamber and passing
out at or near the said end.
3. In a furnace the construction of the furnace chamber substantially as herein
indicated so that goods may be passed intermittently or continuously in succession
therethrough the heat being applied to the furnace by combustion of gas at or
near the middle part thereof, so that the heat is greatest at or near the said part
and diminishes towards the ends of the furnace chamber where the goods are
respectively admitted and discharged; the burning gas travelling towards the
inlet end of said furnace chamber and passing out at or near the said end, into
a return flue or flues, separate flues being provided for the products of combustion,
for the air, and if desired for the gas also, such flues being arranged so that
heat from the products of combustion is transferred to the air and if desired to
the gas also, before the air and gas meet to burn.
4. In a furnace the construction of the furnace chamber so that goods
may be passed intermittently or continuously in succession therethrough, the heat
being applied to the furnace by the combustion of gas at or near
the middle part thereof, so that the heat is greatest at or near the said part
and diminishes towards the ends of the furnace chamber where goods are respec-
tively admitted and discharged, the air for combustion entering at the discharging
end and being heated by the goods or their containers in the said furnace and
serving also to cool said goods or containers, the combustion gases passing to the
inlet end of said furnace and there escaping therefrom.
5. The construction of furnace substantially as herein before described and
illustrated in the annexed drawings.
Dated this 7th day of October 1899.
HERBERT HADDAN & Co.,
Agents to Applicant,
18, Buckingham Street, Strand, London.