Improvements in Furnace Fuel Surfaces and Grates.
Year: 1894

page_text: Date of Application, 1st Aug., 1894-Accepted, 19th Jan., 1895
COMPLETE SPECIFICATION.
Improvements in Furnace Fuel Surfaces and Grates.
I, THEODOR LANGER of Nussdorferstrasse 21 of the City of Vienna, in the
Empire of Austria, Engineer, do hereby declare the nature of my said invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The fire grates at present in use, are all defective in so far, that the majority of
the hard or solid fuels very soon scorify. The decreased free grate-area hereby
caused and the consequent stoppage or clinching of the air passages, which is
difficult to overcome, prevents a constant and regular feeding of the bottom air to
all parts of the combustion chamber and thus renders the combustion of the fuel,
with grates now very widely used-on account of their simplicity,-unreliable,
expensive and difficult to fire.
The construction and the material used in connection with the grates at present
in vogue, prevent the proper burning of the various kinds of fuel.
Owing to the diminution or burning away of the grate-bars by the fire, same
must be made considerably stronger than is really necessary; consequently it is not
possible, even if altogether different forms of grate-bars be used, to feed an
adequate quantity of air of combustion to the fuel in different directions, and which
is uniformly and sufficiently distributed, ou the smallest possible area, so that such
fuel is consumed as completely as possible.
The air-supply canals are too far apart, on account of the relatively too broad
iron surfaces of the grate bars; and on the broad faces of such grate bars which
conduct the heat well, the particles of slag formed without being sufficiently cooled
are kept fluid and in a short time caused to run together more and more and stop
the surrounding openings between the bars.
On account of the necessary breadth of the grate bars, it is all the less possible
to provide sufficient frequent openings of the desired limited size close to each other
for the firing of small and dust-coal and to always prevent saine from being stopped
by the slag. The subject-matter of this invention refers to a mineral grate for
burning all kind of hard or solid fuel on a supported continuous layer of particles
of resistant, refractory stone. These stones are placed on narrow iron supports
(which are as far apart as possible), in the fire box so close to each other, that they form,
as a whole, the floor of the fire box. They therefore form a sieve-like grate with
small projections, which grate is prevented from being displaced to any considerable
extent, by the walls of the hearth, which, however, allow a certain movement of
the individual stones against each other. This ready and easy movement of the
parts forming the grate-area against each other, is exceedingly important. The
grate-area is thereby converted into a shaking sieve, which, when suitably operated,
effects a peculiar rubbing of the individual pieces of stone against each other.
For locomotive fire-boxes the shaking action transferred to the sieve-like strata
of stone by the motion of the engine, is sufficient to make almost all the asbes
resulting from many kinds of fuel, pass into the ash box. A periodical shaking of
the stone is sufficient for fixed or stationary furuaces.
A further excellent effect of this kind of movable grate, in addition to the small
heat-conducting power of same, is effected by the numerous minute air supply
canals formed by the arrangement of the continuous stone layer. The number of
these canals would be increased by employing porous and jagged pieces of mineral
in the ratio of the reduced size of the individual sections of the canals. By choosing

page_text: a special material for the grate i.e. pebbles, hard pieces of slag, broken stones, or
even artificial stones with many small air canals the most advantageous air supply
for every kind of fuel, which is supported by the same device, can be socured and
continuously maintained as hereafter described.
The action of this new grate is exceedingly well adapted for all kinds of fire
places or furnaces and for every kind of fuel, even coal dust of the most slaggy
nature.
With this kind of mineral grate, the light iron frame supporting same is
protected from the direct action of the fire. The separate supports arranged
edge-wise can therefore be made with very narrow bearing surfaces.
Since,
moreover, the grate consisting of the irregularly-shaped stones remains uneven and
jagged both on its upper and under sides, only a very small surface of the supports
comes in contact with the grate-layer, so that the bottom air can pass to every part
of the mineral grate, thereby cooling same, but becoming heated itself. The air is
distributed and passes through innumerable narrow and small canals situated very
closely together and leading to the upper face of the grate, so that a distribution of
air also takes place in the burning layer, and therefore the fuel is uniformly
consumed at every part of the grate; the work of attending to the fire is thereby
considerably lightened.
The material, that is, slag and other remains which has not passed through the
grate during the uniform burning readily forms into heaps, on account of being
sufficiently cooled, without however reducing the size of the canals; they form a
brittle filter, just sufficiently strong to carry the burning layer and possessing the
same properties as the first mineral layer.
By slightly knocking the brittle heaped-up slag with the point of the poker, at
the same time slightly shaking same, such heap can be readily broken into fine
ashes and caused to pass through the mineral layer.
As a larger quantity of this brittle heap is broken up and passes through the
layer when struck with the poker, very few of such regular knocks and shakes
suffice to keep the burning layer completely free from ashes, etc. without disturbing
the equal distribution of the grate-layer.
The movable mineral grate is then capable of supplying a uniform supply of air
for a long time, even without the individual parts being moved.
It will be evident that with fixed or stationary fire places or furnaces, as with
travelling locomotives, the heaping of material is retarded or almost prevented by
constantly or periodically shaking the movable stone layer.
When employing this novel movable mineral-grafe, it has been proved by
practical experiments, that, for instance 250 to 400 miles can be run by a heavy
express-train with always good and uniform combustion and generation of steam,
without a seriously increased heaping of the material taking place. On arrival at
destination, a few blows with the poker are sufficient for rapidly and readily
breaking up the porous heaped up slag which, by passing the poker underneath of
and lifting a part of the mineral grate with same are removed or passed into the
ash-box.
In feeding air in the manner described, the fuel, (even to the most minute
particles) is burnt to ashes with the exception perhaps of a few minute particles of
coal which happens to escape being burnt. As the bottom-air passing through the
innumerable inlets or canals in the grate further serves for effecting complete con-
bustion, so that it can almost be reduced to the theoretical minimum quantity
required, and affords a comparatively less-hindered or free passage through the
pores and canals than is the case with the ordinary grates, the passage of the
individual streams of air is greatly reduced in force or velocity, as compared with
the fire grates now used; furthermore, no cinder is formed and only very little coal
dust is carried above into the flues. This mineral grate, therefore, is an excellent
means for preventing sparks and thus complicated spark-catchers are dispensed
with.
As already mentioned, the rough, jagged upper and lower areas of the mineral-

page_text: grate present many advantages. Rough fuel, consisting of large pieces or cobbles
does not rest on the comparatively broad, flat iron faces of the bars, as is the case
with the present furnaces, but on very small surfaces of the independently-movable
stones, which permits thorough action of the sufficiently-heated air of combustion
after previously cooling the mineral-grate. On the other hand, the numerous recesses of
the stone-grate are well adapted for supporting dusty or fine fuels. These smill
particles which are raised very little from the recesses by the draught are so held
in said recesses that they are consumed before they can fly off or be carried into
the flues; furthermore very little falls through the minute air-canals without being
burnt. Owing to the uneven under-part of the stone grate, only the points or
corners of the individual stones rest on the narrow supports arranged very far
apart, so that practically the whole under face of the stone grate is open to the
action of the cool air of combustion.
This mineral-grate possessing all the properties necessary for effecting a gont
economical and slag-free conibustion of the various fuels, can be readily produced,
by arranging, as afore-described in the form of a continuous layer, hard, porous
pieces of slag or broken stones, of about the size of a hen's egg, on a series of
supports. These supports are arranged in the bottom of the furnace & consist of
flat bars preferably of wrought iron, which should be as narrow as possible and be
placed edge-wise, thus allowing as free a passage as possible for the air to the under
face of the grate.
This grate-surface must be entirely free from pieces of coke which may be
present in the material constituting same; otherwise, such coke would burn anl
thus seriously affect the proper working of the grate by interrupting the continuous
grate surface.
It is therefore of importance that this mineral grate rests on a secondary grate
which affords a large passage for the air to all parts. In constructing this lower or
secondary grate for very long fire-boxes of one uninterrupted or continuous part, the
construction shown in Figs. & 2 of the accompanying drawing is recommended,
Fig. 1 showing in clevation and vertical section such grate construction and
Fig. 2 plan view of same.
The main supports 1 are mounted like ordinary grate bars, on the cross beams a
and . Rack-like cross-bars 2 are arranged on the main supports 1, their distance
apart being regulated according to the length of the fire-place. These cross-bars 2
are mounted at far greater intervals than the ordinary grate-bars and are provided
with a series of notches, in which very light ribs 3 are placed parallel to the
supports 1. One end of these ribs mounted edgewise is so attached to the support 1
by means of a bolt 4 passing through the cross bar 2, or by the plate 5 secured to
the end supports, that each of the light ribs 3 is free to expand. A lateral bending
of such narrow supporting ribs 3 is prevented by their being mounted in the
cross-bars 2.
To prevent the material being deposited on the supports (which would lead to
the grate being rendered inoperative) when cleaning out the fire, the main supports
are always covered by a rib mounted above same and having a knife-like upper
edge. The cross bars 2 also taper towards their upper edges.
Such a supporting device with movable mineral-grate can, for instance, be
constructed for the long fire-boxes of locomotives and are more than half as light
again as grates consisting of grate-bars.
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. An improved movable mineral grate for preventing scorifying of the free
grate-area, thereby characterized that refractory pieces of stones arranged in rows
on a frame-work are kept in a loose position and encased by the walls of the fire
chamber in such manner, that they form a movable, jagged layer allowing air to
pass through and which is a bad conductor of heat; on which layer the fuel rests

page_text: upon such small movable areas of the grate, that the ashes are cooled by finely-
distributed currents of air and prevented from caking together, and by constant or
periodical shaking of the loosely arranged stone-layer are passed or carried off into
the ash-box, substantially as described and shown in the drawing.
2. A grate of the kind described in Claim 1, in which a free supply of the
bottom-air to the upper and under jagged surfaces of the mineral grate is facilitated
in such manner, that said grate is supported by light metal ribs (3), placed edge-
wise and made suitable as supports by being mounted in rack-like cross pieces (2)
tapering towards above and arranged at suitable distances apart on a support (1)
having wedge-like edge and covered by one of the metal ribs (3) in such manner,
that each metal rib can expand longitudinally but not laterally, substantially as
described and shown in the drawing.
Dated this 1st day of August 1894.
W. P. THOMPSON & BOULT,
Agents for the Applicant.