Improvements in and relating to Furnace Grates.
Year: 1896

page_text: Date of Application, 2nd Mar., 1896-Accepted, 30th May, 1896
[Communicated from abroad by OTTO LINDNER, of 148 Rue de Mérode, Brussels,
in the Kingdom of Belgium, Engineer.]
Improvements in and relating to Furnace Grates.
1, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 31, High Holborn, in the County of Middlesex,
6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in the County
of Lancaster, and Lower Temple Street, Birmingham, in the County of Warwick,
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:-
The improvements which form the subject of the present application for Letters
Patent effect the supply of the draught or steam from below in such a manner
that the same comes into contact with the fuel at the points at which the same
rests upon the grate bars, whereby the fuel is prevented from setting fast upon
the bars and the burning of these latter is advantageously avoided. The improve-
ments further effect a crossing of the draught from below entering at the
longitudinal edges of each bar, for the purpose of causing the same to come in
contact with the fuel both from below, that is at the place of support, as also
from above, that is on the opposite side, whereby the object is attained that the
fuel is surrounded on all sides by the lower draught from the time of its first
delivery upon the grate up to the time of its complete combustion continuously
from below and both sides and from above whereby, firstly, complete combustion
of the whole of the combustible gases contained in the fuel is obtained. Secondly,
the burning fast of the fuel upon the grate and thereby the destruction of the
latter is avoided. From both these points of view which display the principles of
the invention the present arrangement of grate differs from all hitherto known
arrangements for up till now grates only have been known in which the lower
draught passes directly from the under to the upper side through slots, openings,
holes, slits and the like, or even sideways upon the fuel resting upon the grate and
passes through the same in such a manner that at those places where there are
no perforations in the bars there is no air or steam current passing through or in
contact with the fuel lying on the grate.
Referring to the accompanying drawings:-
Figure 1 shows a view from above of the grate.
Figure 2 shows a vertical section of Figure 1 on the lines Z' Z and Figure 24
shows a vertical section on lines Z Z.
A A A represent the grate bars of quadrangular cross section and arranged to
lie diamond fashion that is with one angle upwards and the corresponding opposite
angle downwards and in the same vertical plane. The faces of the bars extending
from the uppermost angle of each bar to the right and left are perfectly smooth
and possess no slots, perforations or openings whilst the faces of the bars proceeding
from the opposite lower angle to the left and the right possess a special form
which is defined by the following description.
In order to make the shape of the lower surfaces more clear I have shown a
bar in Figures 4 to 10 of the drawings in various positions as follows:-
Figure 4 shows the bar in plan after the same has been rotated out of the

page_text: position shown in Figure I by 45 degrees to the right on the longitudinal axis
whilst
Figure 5 is a vertical section corresponding to the same position.
Figure 6 shows the same bar in plan after a further rotation to the extent of
90 degrees from the position shown in Figure 1 and Figure 8 shows the bar turned 5
further 45 degrees as compared with Figure 6, whilst the
Figures 7, 9 and 10 show corresponding vertical sections, Figure 9 being a
section on the lines of Figure 8 and Figure 10 ou the line y y of the same.
As shown in the above named sections the bars can be either solid or hollow,
moreover a further modification is shown in Figures 3 and 34 in which under the 1
bars A AA and so forth quadrangular air directors C C or wedge shaped
pieces (which may be hollow or solid) are placed. As shown in the above
named figures each bur is provided on both surfaces coming together at the lower
longitudinal edge with ribs farranged at a right angle to the said lower edge
placed at regular intervals in such a manner that between every two of such ribs
there is a channel 9 which serves as a conduit for introduction of the draught
from below. The arrangement of these ribs and channels y is the same in each
bar and is so planned that on placing the bars alongside one another the side
longitudinal edges lie nearly against each other, and the lines of the ribs of the
one bar meet the channels of the next bar (Figure 1) and thus form a row of
rectangular openings alternately along the angle of each one of the two bars.
A special feature of the arrangements of these channels and projections consists
in giving the lines of division and the surfaces of the same such an angle, that the
draught or steam which is forced in from below under the grate bars passes over
the upper surfaces of the grate bars in the manner indicated by the arrows in the
cross sections 2 and 2º. As is shown by the arrows on those two figures, the
draught of the under surface is somewhat projected over the line of draught of
the upper surface so that the draught arriving in the direction shewn by the
arrows at the lower surface passes at a certain distance above the upper grate
surfaces. If it be requisite to impart to these air or steam currents a given
direction before their introduction into the channels the guide bars C C are made
use of (Figure 3) or the wedge-shaped pieces (Figure 2); the same are so arranged
that a direct upward current of the air or steam is made. possible at the point of
contact of the channels in the vertical direction.
The arrangement above described and illustrated can be applied both for step
or flat grates. The arrangement apparently contradicts entirely the hitherto
expressed opinions in favour of making the free grate surface as large as possible
in comparison with the total grate surface, because the former to a certain extent
here appears to be reduced to a minimum. If the invention be very carefully
examined the opposite will be made clear because essentially the whole grate
surface belongs to the so-called free grate surface, because the draught from below
reaches every place of each grate bar owing to the fact that the penetration of
the draught from below is in a direction parallel to the surface itself,
consequently not as hitherto invariably the case in a direction perpendicular or
inclined thereto.
In the above described construction the fuel is to a certain extent during the
whole time that it lies upon the bars in contact with the air or steam blown in on
all sides and equally, so that in spite of the extremely vigorous combustion no
flames are formed which can injure the boiler plates. The grate bars can be
placed upon a cast iron frame or enclosed in the same so that they shut off
completely the air space below if requisite.
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 furnace grate composed of hollow or solid quadrangular or other single
bars or rods A arranged diamond fashion with their side longitudinal angles close

page_text: to one another the upper faces of which possess no openings for air or steam
currents, but having upon each of the lower faces inclining downwards from the
longitudinal angles channels g and ribs perpendicular to the said angles and so
arranged that at the point of contact of the longitudinal angles of two bars lying
close together the draught coming from below passes upwards approximately
parallel to the upper faces which support the fuel, and is consequently projected
into the fuel.
2. In grate bars as set forth in Claim the arrangement of the projections f
and channels g in each bar in such a manner that by placing the bars close to each
other the side angles touch and the lines of the projections of the one bar fit the
channels of the corresponding bar whereby at the points of junction of their two
side angles a row of openings is formed which lie alternately to the right and left
of the middle line of the junction.
3. In combination with the bars set forth in Claims 1 and 2 the introduction of
the lower draught from below under the projections and the channels g of the
two lower surfaces of the same and in the arrangement of the bars C C or wedge-
shaped pieces D D' so that the draught from below when blown in is obliged to
pass at the junction line of the side angles of two bars approximately parallel to
the upper faces bearing the fuel.
Dated this 2nd day of March 1896.
W. P. THOMPSON & Co.,
31, High Holborn, London, W.C., Patent Agents for the Applicant.