A Manufacture of Porous Magnesian Bricks for the Linings of Stoves, Furnaces, Fire Places, and Flues, and the Construction of Stoves and Furnaces with such Bricks.
Year: 1890

page_text: Date of Application, 23rd Dec., 1890
Complete Specification Left, 22nd Sept., 1891-Accepted, 31st Oct., 1891
PROVISIONAL SPECIFICATION.
A Manufacture of Porous Magnesian Bricks for the Linings of Stoves,
Furnaces, Fire Places, and Flues, and the Construction of Stoves
and Furnaces with such Bricks.
I, OSCAR CLAUSEN of No. 4 Rue Chalgrin, Paris, France, do hereby declare
the nature of this invention to be as follows:-
My invention relates to a new manufacture of porous refractory bricks suitable
for the linings of furnaces, stoves fireplaces and flues, whereby I am enabled to
maintain a greater heat with a less expenditure of fuel than with ordinary stoves
or furnaces.
The essential feature of my invention consists in the substitution of porous
magnesian bricks, covered with asbestos, for the materials heretofore employed for
the above named purposes.
The storing up of heat in the walls of flues or conduits for hot gases depends, as
is generally known, upon the contact of such walls with the hot gases, and not upon
radiation, and the value of the storing coefficient depends upon the height of the
surfaces heated and the radius of the curvatures thereof in a horizontal plane.
The improved bricks, being porous, present in their interior cavities or rough-
nesses, the radius of curvature of which is very small; generally less than one
millimetre, and the magnesia powder which enters into their composition also
presenting large quantities of spherical surfaces having exceedingly small radii,
it is evident that the heat-storage coefficient will attain a very high value.
The adding of magnesia to ordinary argillaceous material in the manufacture of
bricks has the effect of rendering non-refractory bricks refractory.
Such porous magnesian bricks are used, among other purposes, for forming the
walls of stoves and the passages or channels thereof through which the hot gases
pass.
The outer metal or other walls of the stove are made about one centimetre in
thickness, and they are covered with a thin coating of asbestos.
The interior surface of the conduits of porous bricks present in horizontal
section a curvature with very small radius for increasing the coefficient of heat-
storage.
The fire place is lined internally at its lower part with refractory bricks; it is
extended upwards in form of a truncated conc formed of porous magnesian bricks,
and is closed at top by a lateral door for the introduction of the fuel.
The carbonic oxide which is formed at the place of combustion rises into the
cone, but as this is closed the gases cannot escape without passing down through
the fire place again, where they enter into combustion, producing carbonic acid.
which passes through a series of tubes constituting flues through which they are.
led to the chimney.
A more or less perfect combustion is thus obtained.
At the level of the fire place is a small door having an opening serving for the
introduction of air, and having its area regulated by a screw valve, so that the rate
of combustion can be accurately controlled.
Behind this door is a vertical grating which prevents the fuel from falling out
when the door is opened. Underneath the horizontal grate is an ashpit the door of
which is also provided with an opening regulated by a valve.
The outer walls of the stove are covered with a thin covering of asbestos.
A stove constructed as above described is capable of being heated to about 400° C.
as the porous magnesian bricks employed do not allow of the passage through
them of the deleterious gases, such as carbonic oxide which can pass through the
metal walls of stoves when heated to a much less degree.

page_text: The action of the stove is as follows.
The hot combustion gases rise from the fire place through two lateral vertical
flues outside the conical chamber, into a circular space at top, into which open the
upper end of the tubular conduits arranged in a circle near the outer walls of the
stove, and the lower ends of which open into a second circular space at the bottom
of the stove from which the gases escape into an external flue to the chimney.
In applying the said porous magnesian bricks to the construction of blast
furnaces, a similar arrangement to that above described is employed, that is to say,
the entire furnace is lined with such bricks and a series of passages, also built in
such bricks, extend round the conical smelting chamber, such passages being
made to constitute one or more continuous zigzag flues extending round the
furnace, communicating at one end with the boshes and at the other end with an
annular chamber surrounding the said flue which communicates at top with the
discharge flue, so that the whole of the gases are made to pass from the smelting
chamber through such flues and annular chamber, so as to give off the greater
portion of their heat before escaping.
In a similar manner the said porous magnesian bricks may be applied to other
furnaces.
Dated 192.1 1
C n
1000
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
A Manufacture of Porous Magnesian Bricks.for the Linings of Stoves,
Furnaces, Fire Places, and Flues, and the Construction of Stoves
and Furnaces-with such Bricks.
I, OSCAR CLAUSEN, of No. 4-Rue-Chalgrin, Paris, 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::-
My invention relates to the construction of the inner walls of blast and other
furnaces, stoves, fireplaces and flucs, of porous refractory bricks containing
magnesia, in order to obtain a greater concentration of heat while at the same time
employing less fuel, and satisfying sanitary conditions_by_effecting perfect
combustion.
Up to the present time, with-the-best-systems of heating available, the chemical
analyses of the products of combustion, have never given less than from 3 to 4-per
cent. of carbonic oxide, from 8 to 10 per cent. of free oxygen, and only from
7 to 9 per cent. of carbonic acid, together with 79 p.c. of nitrogen.
Moreover, the products escaping up the chimney have still a very high tem
perature, generally above 400 C., which shows that only about half the caloric
power of the products of combustion have been utilised.
With a complete combustion, the analysis of the products of combustion should
be-CO-0 .c. CO2-21 p.c. 0=0 p.c. and N 79p.c. or, when the air and
the fuel are moist: CO=0 p.c. 0-0 p.c. H₂O=2 p.c. CO²=19 p.c. and
N=79p.c., and the temperature-of-these-products should only exceed by a few
degrees that of the outer air.
This latter result I obtain by applying the following principles.
-
I. The draught in the chimney through which the combustion gases escape
should be as small as possible, in order not to carry with it large bodies of air,
which would have the result of lowering the temperature of the fuel.
11. The walls heated by the gases should be made of a material that is a bad
conductor of heat, but which shall readily absorb heat and retain it for a long
time. I obtain these results by the following means.
1. In order to render the draught as weak as possible, it is necessary that the
temperature of products of combustion escaping from the chimney should be as low
as possible, which can only be obtained by constructing all the flues and passages

page_text: for the gases of a material which readily absorbs heat, which property is possessed
by all bricks which are very porous and which, after baking, are plunged into
water in which magnesia is suspended in a finely divided condition.
The porous nature of the bricks enables them (like platinum sponge) to draw in
and concentrate in them a large quantity of heat, which property is increased. by
the presence of magnesia powder, the particles of which are deposited in the pores
of the bricks and thus increase the coefficient of heat absorbed.
2. In order to avoid the frequent cooling down of the combustion chamber when
introducing fresh fuel, I construct the fuel chamber so as to receive a comparatively
large body of fuel, sufficient, for example to last a whole day, the fuel being
arranged in a column above the firegrate so as to descend gradually by gravity as
it becomes consumed below.
3. The openings for the admission of air should be made very small, but in
sufficient number, and of circular form, and arranged at different levels of the layer
of fuel which is in combustion, in order that the air may penetrate into the same in
a uniformly distributed manner; the said openings are provided with means whereby
the supply of air can be regulated, so as to control the quantity of fuel to be
consumed in a given time.
4. The porous magnesian bricks employed for the walls of the combustion
chamber, should also be refractory to a very high degree, as they may often be
subject to a temperature exceeding 2700° C.; the frequent variations in temperature
should also not sensibly alter the volume of these bricks.
5. When the heating apparatus is to serve for heating rooms, the walls of the
smoke flues which serve as heating surface should be able to transmit the heat
rapidly and give it off to the air in the room, which cannot be done by means of a
surface of porous bricks, which is a bad conductor of heat.
For attaining this end, it is necessary to diminish the diameter of each flue or
passage through which the combustion gases pass, and to increase their number and
arrange them in such manner that they are as close as possible to the outer surface
of the stove. This surface is then covered with a material that transmits heat
readily, but that only radiates a gentle heat. Such a material is furnished by
asbestos cardboard of a thickness of about half a millimetre.
By the combination of the above described means, the entire heat supplied by
the fuel will be practically utilised, and the combustion will be effected in a perfect
manner, without producing smoke. The essential feature of the said invention
consists in the use, for stoves, furnaces, flues, and the like, in lieu of ordinary
bricks &c., of porous magnesian bricks, which may be covered with asbestos or
metal (such as boiler tubes).
The storing of the heat in the walls of the flues and chimnies depends, as is
generally acknowledged, upon the extent of contact between these surfaces and the
hot gases, and not upon the radiation from such gases, and the value of the storing
coefficient depends upon the height of the surface and the radius of its curvature in
a horizontal direction, and the degree of roughness thereof. The improved bricks,
being porous, present, in their interior, roughnesses, the radius of whose curvature
is very small, less, in fact, than one millimetre; and the magnesia in the form of
powder which is combined with their surfaces also presents minute spherical
surfaces, so that by these means the heat-storing coefficient attains a very high
degree.
•
In addition, the magnesia which is mechanically added to the bricks after baking
has the effect of rendering these much more refractory.
I will proceed to describe the application of my before described system of
construction to a heating stove, for heating dwelling rooms.
Figs. 1 and 2 shew vertical sections of the stove at right angles to each other;
Figs. 3, 4, 5 and 6 shew cross sections taken respectively on lines 3-3, 4—4,
5-5, 6-6, of Fig. 1.
As above described, the walls A and A¹ of the flues or passages through which
the flames and gases pass, are formed of porous magnesian bricks. The outer

page_text: walls A¹ are made about one centimetre thick, and are covered with a thin covering
of asbestos.
The inner surfaces of the passages, formed of porous bricks, are formed in
sectional plan with projections and recesses having curvatures of very small radius,
for increasing the heat.storing coefficient.
The fire place F is coated internally at its lower part with refractory porous
magnesian bricks; it is extended upwards some distance and is closed at top; in
its upper part is formed a side door a for the introduction of the fuel.
"The carbonic oxide which is given off by the combustion at bottom, rises in the
conical flue chamber C, but as this is closed at top, the gas cannot escape, but has
to descend through the incandescent fuel again, where it is brought in contact with
the air entering through the small holes and is converted into. carbonic acid, which
escapes through the side openings at bottom into the passages or flues DD the
walls of which take up the heat from the gases, which eventually escape through
the chimney flue E. A perfect combustion and utilisation of the heat generated is
effected. At the height of the fire place is a small door e having a number of
small openings through which the outer air enters and which can be closed by a
disc d which acts as regulator, whereby the quantity of fuel consumed in a given
time can be accurately regulated.
Behind the door c is arranged an inclined grating e which prevents the fuel from
falling out when the door is opened. The door c and grating e can be replaced by
a large number of small holes arranged at different levels round that part of the
fuel chamber which contains the incandescent fuel; these holes are provided with
conical stoppers by means of which the air supply can be regulated.
Under the horizontal-fire-grate is an ash pit the door of which also has an
opening that can be more or less closed by the disc d, for regulating the draught
below the-grate..
The outer surface of the stove is covered with a thin coating of asbestos, which
possesses a very high-coefficient of heat transmission, and which can he painted- of
any desired colour.
The action of the stove is as follows: The hot gases from the fire-place-rise
through the lateral passages and annular passage D into the upper circular
chamber from which small flues D descend vertically downwards to an annular
chamber surrounding-the-lower part of the stove, and communicating with the
flue E leading to the chimney.
-On-the_above described principle may be constructed heating apparatus of all
sizes and for various uses, also flues, metallurgical furnaces, such as blast furnaces,
also boiler furnaces, and the like.
In the last named application iron tubes, lined internally with the porous bricks
are arranged to pass through the boiler, and a conical charging hopper, is adapted
to the fire place, provided with the requisite number of small holes for the
introduction of the air supply to the incandescent fuel.
In blast furnaces and other metallurgical furnaces, a construction similar to that
above described is adapted, namely a vertical shaft closed at top through which
the fuel and material to be treated are charged, and surrounding this a number of
vertical-flues-or-passages communicating at top with an upper chamber into which
the hot gases pass from the fuel chamber, and-which communicate at bottom with
other flues leading to the chimney, so that the hot gases, in passing through-such
flues give off their heat to the walls which transmit it back to the central fuel
chamber.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. The use, for the construction of the walls of furnaces, flues, stoves and the
like, of porous bricks coated with magnesia by immersing the same after baking
int water in which maguesia is suspended substantially as described.

page_text: 2. Constructing heating apparatus with passages or flues of small sectional area
placed near the outer surface of the apparatus, which is by preference coated with
a thin covering of asbestos, substantially as described.
3. The application of the herein-described mode of constructing apparatus to all
kinds of furnaces, fire places, beating apparatus and the like, and in particular to
domestic stoves.
Dated this 22nd day of September 1801
ABEL & IMRAY,
Agents for the Applicant.