Improvements in and relating to Pulverulent and Small Fuel Furnaces.
Year: 1896

page_text: Date of Application, 11th Jan., 1896-Accepted, 15th Feb., 1896
COMPLETE SPECIFICATION.
Improvements in and relating to Pulverulent and Small Fuel
Furnaces.
I, MAX SEIPP, of Sophienstr., Berlin, Germany, Civil Engineer, 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 the hitherto known so called coal dust furnaces only quite finely ground or
comparatively dear coal dust, which is carried along by an air current of moderate
velocity, can be used. The supply of the same into the combustion space generally
takes place at the top or at the upper part of the side, but in this way the
coarser coal dust particles are only degasified and fall to the bottom of the
combustion chamber in the form of fine coke which owing to the want of access
of air thereto cannot be completely burnt. Also there no furnace of the kind
known, in which the quantity of blown in or otherwise supplied coal dust, is
regulated automatically in the proper proportion relatively to the quantity of
the air, when the firing is to be augmented or diminished.
It has hitherto been left to the attendant to adjust the coal dust or the air
supply according to his judgement with the result that the quantity of air is often
largely in excess of the quantity theoretically required so as to insure the
prevention of smoke with the uncertain and varying supply of coal dust, or smoke
is often caused in consequence of the insufficiency of air. Impediments are also
occasioned by foreign bodies or dust particles agglomerated into lumps. These
collective disadvantages commonly attending the hitherto known coal dust furnaces
are the causes that such furnaces have not been more extensively employed. Also
the sifting of the coal dust, with the separation of the coarser particles, in the air
current is not suitable for obtaining a proper mixing proportion.
By means of the process hereinafter described, all the above disadvantages of
coal dust furnaces are suppressed and the same converted into real gas furnaces
which may be interrupted or stopped at any time. Only the direct measuring
of the coal dust by a feed roller suitable for the purpose or by another kind of
cubing apparatus which is automatically driven by the air requisite for combustion
purposes and likewise measured by its velocity-therefore for example with half
the quantity of air also half the quantity of coal dust-is suitable for insuring
constantly the proper proportions of the mixture.
In the accompanying drawing which illustrates the invention Fig. I is a part
sectional view of the device for supplying coal dust and air to the furnace and
Fig. 2 is a diagrammattic sectional view of so much of a coal dust furnace as is
necessary to explain the invention.
Practical experience in the application of a screw wheel P, such as is frequently
used for measuring air, for driving a coal dust measuring feed roller W of peculiar
construction, has shewn that this is practicable at a great reduction of speed com-
municated through gearing wheels X shewn in dotted lines (Fig. 1) and with a
depression of 10 millimetres of a water column, that is with a chimney draught of
10 millimetres, and that the recesses in the feed roller are always blown out empty.
by the air flowing by the same into a suitable combustion space, and serving for
the combustion of the coal dust, said recesses therefore being filled afresh upon
cach revolution of the feed roller. The measuring property of the screw wheel is,
as known, based upon the number of its revolutions being, under like conditions of

page_text: friction, with sufficient exactness in the same proportion as the quantity of air
passing through the same. The coal dust container R has therefore only to be so
constructed that with a suitable depth of charge there will always be a like weight
of coal dust pressing down upon the feed roller as now obtains with flour in
flour mills.
The specific gravity of the different kinds of coal is slightly affected by the
different sizes of the particles and therefore with the same screw wheel a particular
feed roller is provided for a particular kind of coal, which roller will deliver at all
velocities coal dust and air constantly in the same proportions. The adjustment
for different kinds of coal, pit coal, brown coal, or turf, may be accomplished in
three ways: Firstly, by altering the capacity of the recesses in the feed roller.
Secondly, by altering the difference of velocity between the feed roller and the
screw wheel. Thirdly, by altering the position of the wings of the screw wheel
or the cross sectional area for the passage of the air.
The supply apparatus being adjusted for the delivery of the quantity of air
theoretically required for the purpose of combustion, said combustion takes place
under the highest possible temperatures and smokelessly. In case it should be
desired to work the furnace beyond the point at which the natural air current
suffices, an exhaustor may be connected to the front or back of the furnace, which
exhaustor, with a steam boiler furnace for example, could have its velocity
regulated by and according to the pressure of the steam.
The combustion chamber A of the furnace is constructed in the form of a
hopper widening upwards and is provided with a layer or lining of highly fire
proof material. The coal dust and air mixture flows through the pipe B and
passages C and then upwards from the bottom or sides like the air in a cupola
furnace. The isolating layer at the same time, upon the flowing through of the
coal dust and air mixture, serves for the preliminary heating and partial
degasification of the fuel by the heat radiating from the interior which in this way
is again utilised in the combustion. The enlargement upwards of the combustion
chamber has for object so to lessen the velocity of the air or gas current that
any incompletely burnt coarse coke particles driven upwards out of the combustion
zone are caused to fall back again into said zone and are not drawn away into
the furnace flue. Lengthy experience has shewn that in this way an uninterrupted
working is practicable and coal dust in quite coarse groat like particles and even
sifted slack of two millimetre particles may be completely burnt, and leave behind
not more but less flying ash in the fire flue, than is the case with ordinary flat or
other grate furnaces.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A process for effecting the thorough combustion in coal dust or gas furnaces
which may be immediately placed out of operation, of coal dust of different
degrees of fineness, ground or unground, consisting in that, even with varying
working, the quantity of coal dust introduced into the combustion chamber is
constantly automatically regulated in the proper proportion to the inflowing air for
combustion and in that slowly burning coke particles always fall back into the zone
of combustion until they are completely burnt, substantially as described and
shewn.
2. For the purpose of carrying out the process referred to in Claim 1, a self
acting supply apparatus comprising a measuring feed roller W or other cubing
apparatus driven either direct or indirect from a screw wheel P or other air
measuring apparatus and constantly automatically maintaining the proportions of
the mixture of the coal dust and air for combustion, substantially as described
and shewn.
3. For the purpose of carrying out the process referred to in Claim 1, a
combustion chamber, having the form of a hopper, or similarly enlarged upwards,

page_text: in which the velocity of the air or gas is so diminished towards the top or sides
that the slower burning coke particles are caused always after ascending to fall
back again into the coal dust and air current entering from underneath, or from
underneath towards the sides, until the complete combustion of the same in the
combustion zone is effected, substantially as described and shewn.
Dated this 11th day of January 1896.
THOMAS R. SHILLITO,
89 Chancery Lane, London, W.C., Agent for the Applicant.