An Improved Method of and Apparatus for Promoting Combustion in Steam-boiler and other Furnaces.
Year: 1896

page_text: Date of Application, 19th June, 1896-Accepted, 25th July, 1896
COMPLETE SPECIFICATION.
An Improved Method of and Apparatus for Promoting Combustion
in Steam-boiler and other Furnaces.
We. JOSEPH ANATOLE CLÉMENT, Mechanical Engineer, of 214 Rue des
Pyrénées, Paris, and GEORGES JEAN JULES. CATON, Gentleman, of the Château
du Cormier, Corme-Ecluse, Charente-Inférieure, both in the Republic of, France,
do hereby declare the nature of this invention to be as follows:-
'Our invention relates to an improved method. of and apparatus for promoting
combustion with the employment of accelerated draught, applicable to furnaces of
various kinds, for the purpose of obtaining an economy of fuel and perfect
combustion of the smoke."
Our invention consists, essentially, in producing the rapid and several times
repeated circulation of the same mass of air for supporting combustion, through the
fuel, by means of an exhausting or blowing apparatus of any suitable kind, so as to
ensure complete combustion, without the production of smoke or carbonic oxide,
whilst only circulating through the furnace just the weight of air theoretically
necessary for such combustion.
Our said invention can be applied to furnaces of all kinds, to glass-furnaces, gas-
works, steam-generators in which very poor fuel is burnt, such as bagasse, lignite,
etc., in a word, to all industrial and domestic furnaces, where it is desired to obtain
economy of fuel and the absolute suppression of smoke.
In order that our said invention may be clearly understood we have illustrated
in the accompanying drawing, in principle, by way of example only, the application
of our invention to the furnace of an "elephant " boiler.
Figure 1 shows our invention carried into practice by means of a steam-blower.
'Figure 2 shows a modification in which our invention is carried into practice by
means of a fan.
In these two figures, like letters of reference indicate corresponding parts.
In this drawing:
A indicates the body of the boiler in section; B the left-hand heater; C the'
grate; D the furnace door or fire-door; E the ash-pit; e a sheet-iron guard or
deflecting plate for causing the air from the exterior to pass over water contained
in the ash-pit before passing through the fire-bars or grate; F a hollow fire-
bridge; G a return flue; H a flue for carrying off the products of combustion ;*
I a collecting flue leading to the chimney; J a damper; K a steam-blower; L a
steam-pipe; M a regulating cock; 'K' a rotary fan or blower.
Our method can be very easily applied to already existing installations as well
as to that shown in the drawing. It is only necessary to erect, for example, a
steam-blower K in the smoke passage. This blower operates by the action of a
jet of steam which is projected through a series of cones, and communicates its
motion to the products of combustion. The steam-blower delivers into the flue G
and in the inlet of the latter is arranged the mouth of the passage' H for carrying
off the smoke; this mouth-piece is covered by a metal gauze cap N forming a
sieve or strainer which serves to filter the products of combustion passing to the
collecting flue I.
The apparatus operates as follows:-
The fire being lighted and the blower K being set in action, the air which enters'
through the coal is caused, by means of the deflecting plate e, to pass over the

page_text: water contained in the ash-pit, it then passes through the grate C and promotes the
combustion of the coal; the products of combustion pass under the heaters B, and
rising, envelope the semi-tubular body A of the boiler, and pass through the interior
of the tubes and enter the smoke-box. Here the products of combustion are drawn
by the steam and enter the blower K. At the lower part of the latter are the
openings of the two flues G and H; the flue H is always of much smaller
section than the flue G, this section being so calculated that, taking into account
the pressure imparted to the gas by the blower K, the flue H can continually
carry off the volume of air theoretically required for the combustion of the coal.
As regards the smoke which passes into the flue G, it is conducted into the
hollow fire-bridge F part issuing above and part below the grate C.
The steam-blower K shown in Figure 1, may be replaced by an exhausting and
blowing fan K, Figure 2, mounted in a flue which conducts the products of
combustion to the chimney.
The whole of the products of combustion pass in at the inlet or exhausting
aperture of the fan, the discharge of which delivers into the return-smoke-flue G,
which leads to the hollow fire-bridge F.
Diametrically opposite to the discharge-aperture of the fan is provided a
branch-pipe H of somewhat small diameter, delivering as above mentioned into
the collecting flue I which leads to the chimney.
In the interior of the fan is arranged a sheet of metallic gauze or other
strainer N1 serving to filter the products of combustion which pass into the
pipe H and thence to the chimney. The fan may be driven in any suitable
manner.
The damper J being closed, and the fan in motion, the products of combustion,
air, smoke, carbonic, acid, air partially burnt or carbonic oxide, etc., reach the
inlet of the fan, are driven forward by the vanes thereof, and escape partly
by the discharge-aperture and partly by the pipe H which delivers into the
collecting flue I.
The relative proportions of the transverse sectional areas of the discharge-
aperture and of the pipe H are about 1: 3, that is to say, for each volume of gas
going to the chimney, 3 volumes return via the discharge-aperture of the fan to the
flue G leading to the fire-bridge.
We wish it to be clearly understood that we can use other suitable apparatus
for exhausting or blowing, such as fans of all kinds, pumps, blowers, water tromps,
injectors operating with compressed air, etc.
According to our arrangement it will be seen that, for one volume of air which
escapes through the flue H, three or four volumes are returned to the furnace,
which then becomes the seat of an excessively active and intense circulation.
It is this active and frequently repeated circulation of the same mass of air
through the furnace, for the purpose of employing the oxygen which would have
escaped through the first flues or passages, which constitutes the characteristic and
novel feature of our invention.
In fact if, when using the chimney only, the passage of air through the furnace
be limited to the theoretical quantity, the draught would be so sluggish that the
combustion would be very imperfect, the coal would distil forming a very dense
smoke and the air be converted into carbonic oxide only. Moreover, in ordinary
furnaces, almost twice the weight of air theoretically required is admitted so as to
obtain complete combustion, and then a considerable weight of air is uselessly
heated which carries off more than 20 per cent. of the heat developed in the
furnace.
According to our method, on the contrary, the rapid and intense circulation
causes the same mass of air to pass several times through the coal, and all the
oxygen which has not been consumed in the first passages is afterwards caused to
combine and be converted into carbonic acid.
Moreover, the air which passes to the underside of the grate from the fire-bridge
mixes with and diffuses into that which comes from the exterior and thus heats it

page_text: and renders it more fit to burn the coal, it is moreover slightly charged with vapour
water and this, in contact with coal, is converted into carbonic oxide and hydrogen
gas which are very combustible.
To light up the furnace, it is only necessary to raise the damper J and the
products of combustion, after having passed through the boiler-Hues, circulate
around the blowing apparatus K or K'; as soon as the pressure is sufficient in the
boiler the valve M is turned and the blower set in action, the damper J is lowered,
and the circulation of the gases takes place as above described.
Evidently by returning the products of combustion to the furnace, the hydro-
carbons therein are burnt, but the active circulation resulting from our method of
working prevents them from being formed.
It will be understood that we can also install our apparatus in front of the furnace,.
and this case, we provide a return-tube for receiving the products of combustion.
after their passage through the boiler, these products, drawn by the steam-blower,
are additional to the quantity of air required for combustion, and pass again through
the grate, a volume of air, equal to that which is admitted at the blower, being
carried off by the chimney.
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. The improved method of promoting combustion with accelerated draught,
consisting essentially in producing a rapid and several times repeated circulation of
the same mass of air for promoting combustion, through the fuel, by means of an.
exhausting or blowing apparatus of any suitable description, substantially as
hereinbefore described and for the purposes specified.
2. A blowing or exhausting apparatus arranged in combination with the furnace
and flues of a steam-boiler substantially as described with reference to either of
the forms or modifications shown in the accompanying drawing, for the purposes.
above specified.
Dated this 19th day of June 1806
D. YOUNG & Co.,
11 & 12 Southampton Buildings, London, W.C.,
Agents for the Applicants.