Improvements in Grates for Steam-boiler and like Furnaces.
Year: 1898

page_text: Date of Application, 13th Sept., 1898-Accepted, 26th Nov., 1898
COMPLETE SPECIFICATION.
[Communicated from abroad by THE MCKENZIE FURNACE COMPANY, a Corporation
organised and existing under and by virtue of the laws of the State of
Illinois, and having its principal office or place of business at the Western
Bank Note Building, Chicago, Cook County, Illinois, United States of
America.]
Improvements in Grates for Steam-boiler and like Furnaces.
I, WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45, Southampton Buildings, in the County of Middlesex, 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 object of the invention is to provide a simple, economical and efficient grate;
and the invention consists in the features, combinations and details of construction
hereinafter described and claimed.
In the accompanying drawings, Figure 1 is a vertical sectional elevation of a
boiler and furnace fitted with a grate constructed in accordance with my improve-
ments; Fig. 2 an enlarged plan view of a portion of a grate constructed in accordance
with iny improvements; Figs. 3 and 4 are sectional elevations taken on lines 3 and 4,
respectively, of Fig. 2; and Fig. 5 a transverse sectional elevation taken on the
line 5 of Fig. 2.
In the art to which this invention relates, it is well known that in the grates now
in common use a certain amount of grate surface is needed to generate sufficient
heat units to evaporate a given number of pounds of water to get the required boiler
pressure. This is so well known that in planning furnaces a certain amount of space
is generally insisted upon in order to obtain the necessary heat units. It is also
well known that in the use of bituminous coal, such coal will clinker and clog the
ordinary grates now in use, and that in order to overcome this various styles.of
grates have been invented, a great many of the type known as shaking grates and
mechanical stokers. This invention, therefore, is intended primarily to provide a
grate of such construction that a less amount of grate space is necessary to generate
the required heat units than has hitherto been required as the standard. A further
object of the invention is to provide a grate of such construction and arrangement
that shaking is unnecessary and that will minimize the objections of "running" of
the coal and clogging of the grate-all of which will be more fully hereinafter
explained.
In constructing a grate in accordance with these improvements, a grate bar A
is made and provided with an upper surface A¹ constructed of longitudinal and
transverse bars a and a¹, the tranverse bars having projections, lugs or teeth a²
opposite each other, so as to form what might be termed double comb-shaped
apertures a arranged transversely so as to pass through the surface of the grate
bars. These teeth a² are tapered downwardly, as shown particularly in Fig. 5,
so as to afford clearance for the ashes of the coal and allow the same to readily pass
through the openings.
In order to support the grate surface in an efficient manner and provide for the
admission of atmospheric air to the burning fuel, the grate bar is provided with

page_text: a lower longitudinal sustaining portion A2 and each transverse rib or bar a¹ is
supported by means of partitions or ribs A³ which are vertically and transversely
disposed and extend from the upper to the sustaining portion and connect them in
one integral bar. These partitions or ribs are concaved at the sides, as shown
particularly in Figs. 1, 3 and 4, so that they form what might be termed arched
recesses B between each grate bar, into which air may pass and circulate in a
cylindrical manner to be detained, and from which sufficient air can always be drawn
to the grate surface to support combustion.
It will also be observed from the foregoing description of the construction and
operation and from an inspection of the figures of the drawings, particularly Figs. 4
and 5, that there is a space between the upper portion of the grate A' which forms
the grate surface and the longitudinal supporting bar A2 which is arranged under-
neath the grate surface. This space between the grate surface and the supporting
bar serves to furnish a continuous conuection between the spaces formed between
the bars so that portions of the air which circulates between the bars may pass
through these spaces and thus facilitate the feeding of air to the fuel box or fire
chamber. This is a material advantage, in that the air is detained and broken up
into currents, which facilitates the feeding of the furnace.
An inspection of Figs. 3 and 4 will show that the lower sustaining portions of the
grate bars are tapered as at A4 and adapted to fit in tapered recesses c of the side
bars C and center bars C¹. In the ordinary furnaces, 4 by 4, it is preferable to
make the grate bars in two pieces longitudinally, as shown in Fig. 5, and support
them on the side and middle bars. The upper surfaces of these side and center
bars are tapered, as at c¹, so that the ashes in falling down will not be retained on
the upper surfaces thereof.
Fig. 1 shows a complete furnace constructed in accordance with the improvement,
in which there are six grate bars, and this furnace is of the ordinary size, 4 by 4,
having 16 square feet. From experiments, however, it has been demonstrated that
while this amount of grate surface is necessary under the old construction of boiler,
it can be cut down at least one bar and a saving of about three feet of grate
surface thereby effected, which is often quite a consideration in crowded centers of
commerce. It will therefore be seen that a grate bar constructed in accordance
with this improvement is more economical to use, in that it requires less space to
generate heat units than in boilers constructed in the old forms.
In use, and from actual experiments, it has been found that the coal burns on the
grate bar in seemingly individual pieces, that is, the coal rests on the teeth over the
comb-shaped openings and is distilled rapidly by the heat of the furnace, so that
the incoming air seems to engage or combine with the distilled gases and burn in jet-
like flames, the ash dropping through readily and easily in small pieces and not
tending to clinker or clog. From these experiments it has been found that the air
comes in through the ash-pit and is resisted by the sustaining portions of the grate
bars and circles between the same, and is held in a measure therein to be easily
drawn up through the openings in the grate surface, the entire grate forming, as it
were, a mesh to economically support the fuel and admit the necessary atmospheric
air and oxygen.
From a glance at Figs. 1 and 5, it will be seen that the air can
pass up through all portions of the grate and between it and the side and end walls,
and at the same time allow the ash to drop down and through the openings.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me by
my foreign correspondents, I declare that what I claim is :-
1. In a grate bar, the combination of a surface portion having double comb-
shaped openings extending therethrough, a lower sustaining portion extending
underneath and lengthwise with the grate bar so as to provide an air space between
it and the grate surface, and two or more ribs or partitions vertically and transversely
disposed to connect the surface portion with the sustaining portion in one integral
portion, substantially as described.

page_text: 2. In a grate bar, the combination of a surface portion provided with transverse
ribs or bars, projecting teeth on each side of the transverse ribs and arranged to
form comb-shaped openings through the grate, a sustaining portion arranged
underneath the grate surface and longitudinally disposed, and a plurality of ribs or
partitions transversely and vertically disposed to connect the surface and sustaining
portions in one integral portion, substantially as described.
3. In a grate, several grate bars each having a surface portion provided with a
plurality of double comb-shaped openings extending therethrough, a lower wedge-
shaped sustaining portion arranged in line with and underneath the grate surface so
as to provide an air space between it and the grate surface, and a plurality of
vertically and transversely disposed ribs or partitions connecting the surface and
sustaining portions in one integral piece, in combination with supporting
rods or bars provided with tapered recesses to receive the sustaining portion of the
bars and hold them in fixed operative position, substantially as described.
4. In a furnace grate, the combination of several grate bars formed of upper
service portions having a plurality of double comb-shaped openings transversely
disposed and extending therethrough, lower wedge-shaped sustaining portions longitu-
dinally disposed arranged underneath the grate surface so as to provide an air space
between it and the grate surface, a plurality of webs or partitions connecting the
surface and sustaining portions in integral portions and concaved at either side so
as to provide arched recesses between adjacent grate bars into which air may
circulate and be distributed, and side bars for the furnace provided with wedge-
shaped recesses or pockets in their upper portions to receive the sustaining portions
of the grate bars and removably hold the grate bars in fixed operative position,
substantially as described.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.