Improvements in Furnace Grates and Fire Bars for same.
Year: 1892

page_text: Date of Application, 2nd Mar., 1892-Accepted, 2nd Apr., 1892
COMPLETE SPECIFICATION.
Improvements in Furnace Grates and Fire Bars for same.
I, CHARLES WHITFIELD of Union Street, Kettering, in the County of
Northampton, 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 ascer-
tained in and by the following statement :-
The object of my invention is to provide an improved arrangement of the bars
of steam boiler furnaces to more effectually consume the smoke produced by such
furnaces. I have found in constructing steam boiler furnaces this is most effectually
accomplished by a differential spacing of the fire bars from the fire door towards
the bridge, that is, with a maximum amount of air space at the front near the fire
door and gradually diminishing towards the bridge. The combustion on a grate
built in this manner is most intense at the fire door end of the grate whilst at the
bridge end the combustion although not so active is sufficient to keep the fuel in a
state of incandescence and is very effective in raising the passing gases up to the
necessary temperature to produce perfect combustion at the bridge.
My invention consists in constructing a grate embodying the beforementioned
principle by making by preference one third the grate of ordinary fire bars whilst
the other two thirds are formed of hollow bars for heating the air on its way to
the bridge.
And in order that this my said invention may be readily understood and carried
into practical effect 1 have hereunto annexed a sheet of drawings illustrative of my
improvements and will now proceed to describe the same with the assistance of the
various figures and letters of reference marked thereon.
Fig. 1 is a plan view and Figs. 2 and 3 transverse sectional views.of a furnace
grate embodying my improvements.
Figs. 4 to 12 are similar views of modifications of my invention and Fig. 13 is a
side elevation of Fig. 10 shewing my improved furnace in combination with a
supplementary fire bridge.
In carrying out my invention according to one modification as in Fig. 1; i con-
struct my improved furnace grate of tapering fire bars A. A. the thinner ends of
such bars being situated in the front portion of the furnace and the wider ends at
the rear portion of the furnace so that when such bars are put together air
spaces B. B. are produced tapering from front to back of the furnace. The fire
bars of this form of my improved grate are by preference formed in two portions,
the front being solid as illustrated in Fig. 2 whilst the rear portion is hollow as
illustrated in Fig. 3 for the passage of air to the back of the fire grate.
Figs. 4, 5 and 6 illustrate a furnace grate built up of "stepped" fire bars C. C.
the sides of every third or other suitable length of the bar being parallel instead of
tapering thus forming "stepped" air spaces D. D. diminishing in width for every
third or other suitable length of the bar from front to back of the furnace, and
reducing the spaces in the rear portion of the grate to just sufficient width to keep
the fuel in a state of incandescence.
These last mentioned bars are formed in two portions as illustrated the rear
portion being formed in halves with cavities or channels in their inner faces which
when put together equal the thickness of the hollow fire bars aforesaid and form
air passages as illustrated.
Figs. 7, 8 and 9 also illustrate a grate composed of "stepped "bars formed in
two portions the rear portion however being cast hollow as in the case of tapering
bars in Fig. 1. Figs. 10, 11 and 12 illustrate another furnace grate built up of
"stepped" bars formed in one continuous length with air slits or openings E. in

page_text: the front portion which come opposite air passages in the rear portion of the fire
bar as illustrated.
In this manner I construct furnace grates with diminished or differential air
spaces from front.to.back of the furnace a small amount of air space sufficient to
keep the fuel in a state of incandescence being at the back of the furnace whilst
a large amount of air space is provided at the front of the furnace where it is
most required in order to give a copious supply of air to the fuel, which is thrown
on that portion of the grate from time to time so as to ensure that the smoke
produced at the front of the furnace shall be completely consumed after passing
over the incandescent fuel in the rear portion of the furnace..
In order to increase the smoke consuming properties of my improved furnace
grate I prefer to employ a supplementary bridge F behind the ordinary bridge as
illustrated in side elevation Fig. 13 the heated air drawn through the hollow
portion of the fire bars by this means being deflected upwards.
Having thus particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I wish it to be understood
that I do not claim the hollow bar, but I claim as my invention and desire-to secure
by Letters Patent.―
1st. Producing a fire grate with tapering air spaces substantially as and for the
purposes herein before described and illustrated in Figs. 1, 2 and 3 of the accom-
panying drawing.
2nd. Producing a fire grate in which the bars are so arranged as to provide a
series of two or more "stepped" or differential air spaces substantially as and for-
the purposes herein before described and illustrated in Figs. 4 to 14 of the accom--
panying drawing.
3rd. The combination of the tapering or stepped air spaces aforesaid with the
hollow bars shewn in Figs. 3, 6 and 9 and 12 of the supplementary fire bridge Fas
and for the purposes described.
Dated this 27th day of February 1802.
JOHN G. WILSON,"
Agent for the, Applicant.