A Method and Means for Effecting Smokeless Combustion in Steam Generator and other Furnaces.
Year: 1898

page_text: Date of Application, 12th Dec., 1898-Accepted, 11th Nov., 1899
COMPLETE SPECIFICATION.
A Method and Means for Effecting Smokeless Combustion in Steam
Generator and other Furnaces.
I, ALBERT KOEPPE, of 3111, Felixstrasse, Anger-Crottendorf, Leipzig, in the
Empire of Germany, Machinist, 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:-
This invention relates to a method and means for effecting smokeless com-
bustion in steam generator and other furnaces, in which the air is not supplied
to the grate surface upon which the combustion of the fuel takes place from
below, but from such a point as will cause only the upper and free layer of fuel
to be maintained in incandescence, and consequently the smoke and combustion
gases are forced back into the layer of fuel ready for combustion; air which has
been previously heated being supplied to the fire if desired.
A constructional form of apparatus for carrying out my invention is illustrated
in the accompanying drawing, in which:
Fig. 1 is a longitudinal section through a furnace, a steam generator furnace
for example, and
Figs. 2 and 3 are respectively a horizontal and a cross section through the
same.
By means of the invention hereinafter described it is possible to obtain smoke-
less combustion. This result is attained owing to the fact that the air necessary
to support the combustion of the fuel is not supplied from below through the
grate bars, as in furnaces as hitherto constructed, but above such bars. In
addition to this, the air is advantageously not supplied in a cold condition, but
is previously heated to a certain temperature.
Owing to the fact that the air supply takes place above the grate bars upon
which the fuel is heaped, it follows that the starting or generating point of
the fire is sustained from in front, and the upper layer of the fuel brought to
and maintained in a state of incandescence. As a consequence of this, the hot
gases given off pass over the incandescent fuel, and force any smoke which may
exist back amongst the fuel, thus causing its gradual combustion, so that the
gases passing off through the flues consist of hot gases of combustion. Smoke
or smoke gas is forced back in the direction of the ash pit, but as it is unable
to escape in this direction owing to the closing of the ash-pit, it is merely
forced into the fuel which is heaped upon the grate bars in suitable quantities,
there stored and gradually consumed with the incandescent layer formed upon
the surface of the heap of fuel.
In order to obtain these results the arrangement of the furnace is such that
in the first place the space forming the ash pit of the furnace, and which is
covered by the grate bars, is rendered as air-tight as possible, and is only
opened in case of necessity, such as for the purpose of clearing the ash-pit. The
grate surface consists of two layers of grate bars; the rear layer of bars A being
fixed, whilst the front layer of bars B (which are advantageously shorter than
the bars A) are pivoted at C, or otherwise so mounted as to be capable of being
turned upon or at such point C.

page_text: The fuel is arranged upon the rear fixed grate bars A, and heaped as high as
the fire bridge. The wood or other igniting material is piled up on the front
and shorter grate bars B, this pile forming the starting point of the fire. The
air supporting the combustion of the fuel is supplied to the furnace from the
front, either through the furnace door itself, or by means of a special device
hereinafter described. This air supply may be regulated by means of a suitable
regulating device, as in furnaces as hitherto constructed. When the igniting
material has been ignited, and the air supply aperture opened to a suitable extent.
its combustion will take place upon the first displaceably arranged layer of
grate bars B, communicating its incandescence to the adjacent fuel, and igniting
the upper layer of fuel over which the hot gases pass owing to the nature of the
air supply. By this means the upper layer of fuel is rendered of a white heat
upon the combustion of the igniting material, and the heap of fuel is gradually
consumed in a downward direction.
When it is necessary to supply fresh fuel, the slag is first of all separated
and brought to the front of the furnace upon the movable grate bars B, and the
incandescent mass is pushed back upon the fixed portion of the grate. The front
grate bars B are then swung down by means of the bell crank E at each side
(pivoted at E), one arm of which is connected to the bars B and the other arm
connected to the operating rod D at each side-so that the slag and ash may fall
into the closed ash pit F. These movable grate bars B are then replaced in
their nornial position, and the incandescent fuel drawn forward upon them,
whereupon the smoke damper is closed, and fresh fuel placed upon the fixed
portion A of the grate. The incandescent portion of the fuel is thus again
arranged upon the front of the grate, and in front of the fresh supply of fuel.
With a suitable air supply the upper layer of this fresh stack of fuel is again.
brought to incandescence, without its being possible for any smoke to escape,
because the hot gases pass over the freshly supplied fuel.
In addition to the smokeless combustion which is obtained, other important
advantages are secured by means of my invention; for example, burning of
the grate bars is prevented, as it is not the fuel resting upon them which becomes
incandescent, so that the prevailing temperature there is comparatively low.
The stoker is also protected from any backward rush of flame or the like, such
as frequently takes place in furnaces of the usual construction. No emission of
smoke or dust takes place through the closed ash pit, amongst the machinery,
or into the boiler room, causing dirt and other troubles. The preliminary heating
of the combustion air is effected by arranging in the flues of the furnace a
spiral or other coil of pipe Z which opens into the outer air through which the
air supply enters. On its passage through this pipe Z, which is surrounded by
the hot gases passing off, the air becomes heated, and reaches the grate at a
suitable temperature. The apertures 7 for the admission of this previously
heated air into the grate itself may advantageously be arranged upon a fire har
upon the hearth, or upon the furnace beam (supporting the fire bars) itself.
The admission apertures of the air supply are provided with dampers or the like,
so that the quantity of air admitted may be regulated at any time. Owing to
the fact that incandescence takes place at the top of the fuel in this furnace,
not only is smoke prevented from issuing from the furnace through the flues,
but greater intensity of heat is obtained, and the heating capacity of the furnace
therefore greatly increased.
In addition to this, economy both in fuel and in plant is obtained.
If for any reason it is desirable to admit the air-supply through the ash pit F
(that is to say beneath the grate) it is only necessary to open the ash pit doors.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:—
1. The hereinbefore described method of effecting smokeless combustion of

page_text: solid fuel in steam generator and other furnaces, which consists in closing the
ash-pit of the furnace in an air-tight manner, and admitting the air necessary
to support combustion at a suitable point above the grate surface, so that incan-
descence may spread through the grate from the front thereof, over the fuel,
causing the uppermost layer of such fuel towards the back of the furnace to
become incandescent, so that passage of the smoke through the flues of the
furnace is obviated substantially as set forth.
2. A method of effecting smokeless combustion in steam generator and other
furnaces in accordance with Claim 1, in which the air admitted to the furnace
is heated, prior to its admission, by the hot furnace gases, for which purpose
such air is caused to enter through a pipe, such as Z, arranged in the flues of
the furnace, substantially as described and illustrated.
3. For effecting smokeless combustion in steam generator and other furnaces
in accordance with Claim 1, the arrangement of a grate surface consisting of two
or more layers of grate bars, or the like, of which the front layer B is pivoted
upon one of its points of support, such as C, and means to swing or rock said
bars B about said point C as and for the purposes described.
4. The improved furnace constructed and arranged to operate and operating
substantially in the manner and for the purposes hereinbefore described, and
illustrated in the drawings hereunto annexed.
D
101 1
3000
TONGUE & BIRKBECK,
Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.