Improvements in Furnace Grates and Appliances in Connection therewith.
Year: 1889

page_text: Improvements in Furnace Grates and Appliances in Connection
therewith.
I, GEORGES ALEXIS-GODILLOT of No. 23 Boulevard de Strasbourg Paris France
Engineer do hereby declare the nature of this invention and in what manner the
samo is to be performed to be particularly described and ascertained in and by the
following statement:―
This Invention relates to a construction of furnace grates with superposed bars,
and troughs containing water for cooling the said bars, the water being supplied to
the uppermost trough from which it flows successively through: the lower ones down
to the bottom of the grate.
Figures 1. 2 and 3 of the accompanying drawings shew respectively a longitudina_1
section, a cross section, and a plan of one arrangement the improved construction of
stepped grate as applied to a steam boiler.
Each semi-circular bar B has on its underside a rib a which dips into the water of
a trough A.
The water enters at 6 into the uppermost trough and it flows down from this from
trough to trough. At the lower part of the stepped grate, that is to say, towards
the fire bridge is arranged a moveable horizontal grate to which can be imparted
a jolting motion at intervals, so as to cause the ashes and clinkers of the fuel to fall
from the same as they accumulate. The construction of this grate is shewn in section
to an enlarged scale at Figure 4, together with the two lowest bars and troughs of the
stepped grate.
The horizontal grate is formed of straight bars C resting upon sheet iron bearers c c
which are rivetted or bolted to the uprights d d which are in their turn rivetted to
bearers e e.
These. latter extend through the walls of the furnace as shown at
Figure 2, the bearer at one end of the grate being connected to the one at the other
end of the grate outside the furnace by connecting bars ff to which are attached
vertical rods g g by means of which the before mentioned movement is imparted to
the grate. The rods g are for this purpose connected to chains which pass over
pullies carrying balance weights p p. Thus by raising and lowering the weighted
chains the required jogging motion may be imparted to the horizontal grate:
This arrangement of moveable horizontal grate. may also be applied to stepped

page_text: grates in which the bars, instead of being semi-circular, and of decreasing size
towards the top, are straight and all of the same length. A construction of this kind
is shewn at Figures 5. Figures 6 and 7 shew detached cross-and part longitudinal-
sections of the grate bars and troughs of this arrangement to a larger scale. The
bar B is in this case cast in one with the water trough A. situated behind it. The bar
is formed with ribs a by means of which it rests upon the bar and trough immediately
below it, so that the bar is cooled by the contact of its ribs a with the water in the
trough below, the ribs being formed with openings c for allowing the free circulation
of the water through the length of the trough.
Figures 8 and 9 shew a modification in which the bar B is made to project back-
wards partly over the trough A., cast in one therewith.
In these arrangements, Figures 6. 7. 8 and 9, the overflow of each trough passes
down into the next trough below through openings and grooves k formed in the
inner wall of the trough.
This overflow arrangement is also applicable in modifications such as shewn at
Figures 11 and 12 where the bar B is formed separate from the trough A. In either
arrangement, whether the bar be cast in one with or be separate from the trough,
the overflow may be arranged as at Figure 10 in which a tubular projection dis
formed in the bottom of the trough extending to a height corresponding to that
at which it is desired to maintain the water level. The lower end of the tube is.
formed with an incline in order to allow the descending liquid to issue freely and.
to prevent choking by deposit..
The back part of the trough instead of being inclined may be formed vertical as
at Figure 13.
The excess of water falling from the lowest trough of the stepped grate passes
on to the edge of the horizontal grate E which is thereby also cooled, and from
this the water falls into the ash pit D where it collects in a sort of basin from which
an overflow channel leads the excess away.
The fixed horizontal grate E is by preference extended in front of the stepped
grate as at Figure 5, the moveable grate C being in this case placed further
inwards.
•
By this arrangement the moveable grate can be lowered to the required extent in
being jolted without causing the fuel situated upon the stepped grato to slide
downwards, such fuel being retained by the fixed grate E.
The above described fire grates can be fed with fuel from hoppers or otherwise;
for example, an arrangement such as is shewn at Figures 1 to 5 can be employed.
In ordinary arrangements of this kind the fuel is supplied only to the outer end
of a casing containing the screw feeding blade, the rotation of which by a crank
handle or otherwise feeds it into the grate. During such horizontal travel of the
fuel this is in frictional contact with the stationary fuel situated in the hopper
immediately above. By providing for a vertical descent of the fuel throughout the
length of the hopper, I avoid such friction and I effect this by so forming the feeding
screw that each turn of the helix discharges the mass of fuel situated upon it. For
this purpose it suffices that the space between two turns of the blade be made to
increase gradually from the inlet to the outlet end. This increase can be effected in
various different ways, namely, either by increasing the pitch of the screw, by
decreasing the thickness of the screw blade, by increasing the diameter thereof, by
decreasing the diameter of the central boss, or lastly by combining two or more of
these means.
Figure 1 shews an arrangement in which the space is increased by decreasing the
diameter of the boss.
Figure 5 shews an arrangement in which the pitch of the screw is increased, at
Figure 14 the thickness of the blade is made to decrease--at Figure 15 the diameter of
the blade is made to increase, the boss remaining cylindrical; at Figure 16 the
increase of the space is effected by a combination of the above means.
The feeding screw may be of cast or wrought metal similar to screws of the ordinary
kind.

page_text: 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
1. The construction of stepped grates wherein superposed bars of semi-circular or
straight form having troughs containing water, for cooling the bars, are combined
with a moveable horizontal grate at the lower end thereof arranged and operating sub-
stantially as herein described with reference to the accompanying drawings.
2. The various constructions of stepped grates with superposed water troughs, pro-
vided with overflows arranged and operating as herein described with reference to the
accompanying drawings, such grates being constructed either of semi-circular or of
straight form.
3. The combination with the semi-circular or straight stepped grate and moveable
horizontal grate referred to in the first claim, of a fixed horizontal grato projecting in
front of the stepped grate, for the purpose of retaining the fuel thereon when the
moveable grate is lowered substantially as herein described.
4. The combination with the construction of furnace grates referred to in the pre-
ceding claims, of fuel feeding apparatus having feeding screws constructed as herein
described with reference to Figures 1, 5, 14, 15 and 16 of the drawings.
ABEL & IMRAY.