Improvements in Fire Grates.
Year: 1897

page_text: Improvements in Fire Grates.
I, PETER JENSEN, of 77, Chancery Lane, London, W.C., Chartered Patent Agent,
do hereby declare the nature of this invention (a communication to me from abroad
by OTTO SIEGERT, of Murowana-Goslin, District of Rogasin, Posen, German Empire,
Merchant), to be as follows:-
Furnace bars have heretofore been made so that the air inlet passages between
them are narrower towards the fire. This causes a compression or squeezing of
the air before its admission to the fuel more particularly so because the air is
materially heated by the sides of the bars. This compression or squeezing has
again the consequence that the air does not get into the fire place with sufficient
speed or in sufficient quantity; there is thus a lack of air and an insufficient or
too late mixture of it with the already evolved but still unburnt gases and this
latter defect is increased by that in the systems heretofore proposed little provision
was made for an ample dividing up of the air for combustion admitted in broad
compact layers. From all these reasons the combustion and the heat in the
fire place are insufficient and a large percentage of unburnt gases and carbon
particles escape unused into the chimney.
In contradistinction to the usual form the essential point in the present grate
consists in that the sum of the sections of all the air inlet passages, or the section
of each passage, increase in size from the bottom to the top but so that they cannot
choke by the falling ashes or clinkers. The grate consists of two kinds of furnace
bars arranged alternately. The main bars have rounded bottom edges and are
about three times as deep as the intermediate shallow bars and decrease gradually
in thickness from the bottom to the top; they are pierced with deep oval or pear
shaped holes in their lower part, and have slots in their upper part which slightly
increase in width downwards; at the bottom they are tapered off towards one side.
The said holes and slots are not opposite each other but intermediate as to those in
each two adjoining bars. The shallow furnace bars are about triangular in section
thinner below where they terminate with sharp corners; these bars have no holes
or slots and are about as deep as the slots in the deep bars; at the top the shallow
bars stand about 1 inch above the deep bars in order to prevent the fire rake from
catching in the slots in the deep bars and damage to these upper parts of same.
The distance at the bottom between two deep bars may be equal to the sum of the
two top spaces between a shallow bar and its two adjoining deep bars. The afore-
said increased area of air inlet is obtained by the lengthways evenly distributed
slots in the deep bars. The upper width of these slots is about of the substance
left between two slots.
The action of this fire grate is as follows: The air for combustion enters below
between the rounded bottom edges of the deep bars and is heated by these bars.
At the same time this air is distributed or broken up by means of the oblong holes
in the deep bars and an equalization of the temperature throughout the grate is
produced. In the lower part of the grate a kind of air reservoir is so to say formed
which gives off an even supply upwards and gets accession of fresh air from

page_text: below. In spite of the expansion of the air by heat it is not compressed or squeezed
as the deep furnace bars decrease in thickness towards the top and thus afford
broader air passages. The same applies to the upper part of the heated air which
expands unhinderedly more and more because the slots afford another increase
of area to the air passages. At the same time the shallow furnace bars and the
slots produce a great subdivision of the preheated air and an intimate and even
mixture with the fuel and the gases evolved. The unhindered air inlet without
compression or squeezing ensures besides a sufficiently sharp draught, so that the
need of air for the fuel or the chimney draught is fully met, and at the right time
before still unburnt gases containing it may be separate carbon particles have
begun to be drawn to the chimney. The ashes and clinkers are free to drop with-
out hindering the air supply and this is favoured by the width of the slots
increasing downward and by the slanting guiding bottom faces of the slots. These
latter also aid the air inlet. The foregoing explains that there is a saving in fuel
and a smokeless combustion.
Lastly it should be noted that in the case of small fireplaces for instance for
house stoves it suffices to make the air outlet as large as the air inlet. For in
such cases the depth of the bars is not considerable, so that the air is not preheated
and expanded much; nor will the air thus be compressed or squeezed. In such
cases the slots and holes in the deep bars may sometimes be omitted. But in no
case must the outlet area be smaller than the inlet area as has hitherto been the
defect in all grate systems.
Dated this Thirteenth day of May 1897
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.
I, PETER JENSEN, of 77, Chancery Lane, London, W.C., Chartered Patent Agent,
do hereby declare the nature of this invention (a communication to me from abroad
by OTTO SIEGERT, of Murowana-Goslin, District of Rogasin, Posen, German Empire,
Merchant), and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
Furnace bars have generally been made so that the air inlet passages between
them are narrower towards the fire. This causes a compression or squeezing of the
air before its admission to the fuel, more particularly so because the air is
_ materially heated by the sides of the bars. This compression or squeezing has
again the consequence that the air does not get into the fire place with sufficient
speed or in sufficient quantity; there is thus a lack of air and an insufficient or too
late mixture of it with the already evolved but still unburnt gases and this latter
defect is increased by that in the systems heretofore proposed little provision was
made for an ample dividing up of the air for combustion admitted in broad compact
layers. From all these reasons the combustion and the heat in the fire place are
insufficient and a large percentage of unburnt gases and carbon particles escape
unused into the chimney.
Figure 1 of the accompanying drawings is a plan of part of a fire grate con-
structed according to this invention.
Figure 2 a vertical cross section through some of the furnace bars, and
Figure 3 a side view of part of a bar.
In contradistinction to the usual form the essential point in the present grate
consists in making the cross section area of each passage, increase in size from the

page_text: bottom to the top but this is done in such a manner that they cannot choke by the
falling ashes or clinkers. The grate consists of two kinds of furnace bars a and b
arranged alternately. The main bars a have rounded bottom edges and are
about three times as deep as the intermediate shallow bars and decrease gradually
in thickness from the bottom to the top; they are pierced with deep oval or pear
shaped holes c in their lower part, and have slots in their upper part which
slightly increase in width downwards; at the bottom they are tapered off towards
one side as shown at e. The said holes c and slots d are not opposite each other but
alternate in position relatively to each other. The shallow furnace bars bare
about triangular in section thinner below where they terminate with sharp
corners these bars have no holes or slots and they extend down as far as the
openings d extend downwardly in the bars a; at the top the shallow bars stand
about inch above the deep bars in-order to prevent the fire rake from catching
in the slots d in the deep bars and damage to these upper parts of same. The
distance at the bottom between two deep bars may be equal to the sum of the two
The
top spaces between a shallow bar b and its two adjoining deep bars a.
aforesaid increased area of air inlet is obtained by the lengthways evenly dis-
tributed slots d in the deep bars a. The
width of these slots d is about
upper
of the substance left between two slots.
The action of this fire grate is as follows: the air for combustion enters below
between the rounded bottom edges a¹ of the deep bars and is heated by these
bars. At the same time this air is distributed or broken up by means of the
oblong holes c in the deep bars and an equalization of the temperature throughout
the grate is produced, In the lower part of the grate is formed a reservoir, so to
say, which gives off an even supply upwards and gets accession of fresh air from
below. In spite of the expansion of the air by heat it is not compressed or
squeezed as the deep furnace bars a decrease in thickness towards the top and thus
afford broader air passages. The same applies to the upper part of the heated air
which expands more and more because the slots d afford another increase of area
to the air passages.
At the same time the shallow furnace bars and the slots d produce a great sub-
division of the preheated air and an intimate and even mixture with the fuel and
the gases evolved. The unhindered air inlet without compression or squeezing
ensures besides a sufficiently sharp draught, so that the need of air for the fuel
or the chimney draught is fully met, and at the right time before still unburnt
gases, containing it may be separate carbon particles have begun to be drawn to
the chimney. The ashes and clinkers are free to drop without hindering the air
supply and this is favoured by the width of the slots d increasing downward and
by the slanting guiding bottoin faces e of the slots. These latter also aid the air
inlet. The foregoing explains that there is a saving in fuel and a smokeless
combustion.
Lastly it should be noted that in the case of small fireplaces, for instance, for
house stoves it suffices to make the air outlet as large as the air inlet. For in such
cases the depth of the bars is not considerable, so that the air is not pre-heated and
In such cases
expanded much; nor will the air thus be compressed or squeezed.
the slots and holes in the deep bars may sometimes be omitted. But in no case
must the outlet area be smaller than the inlet area as has hitherto been the defect
in all grate systems.
Having now particularly described and ascertained the nature of the said inven-
tion as communicated to me by my foreign correspondent and in what manner
the same is to be performed I declare that what I claim is :-
1. In a fire grate the combination of deep furnace bars a decreasing in thickness
from bottom to top and shallow intermediate furnace bars b decreasing in thickness
from top to bottom substantially as and for the purpose set forth.
2. In a fire grate the combination of the deep furnace bars a decreasing in
thickness from bottom to top and shallow intermediate furnace bars decreasing

page_text: in thickness from top to bottom, said deep furnace bars being slotted at their lower
portions and having the slots at their upper portions, substantially as described.
3. In combination in a grate, the deep bars a, and the bars b between them, the
said bars a having the slots d in their upper parts, substantially as described.
4. In combination in a grate, the deep bars a and the bars b between them with
air spaces between the bars, the said bars « having slots in their upper parts
and slanting bottom edges, substantially as described.
-
5. In combination, the deep bars a and the shallow bars between, the said
deep bars having rounded lower edges, substantially as described.
6. In combination, the shallow bars, the deep bars alternating therewith and
arranged with air spaces between, said deep bars having slots extending down
therein from their upper edge and the said shallow bars extending down
substantially the same distance as the slots in the deep bars.
Dated the Fourteenth day of February 1898.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.