Year: 1887

page_text: Date of Application, 22nd Apr., 1887.
Specification Accepted, 24th May, 1887.
We, ROBERT MARSHALL of 121 Fenchurch Street in the City of London Engineer
and WILLIAM CLARK of 15 Fairthorn Road, Lower Road, Charlton in the County of
Kent, 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:-
This invention has for its object to effect increased economy in fuel and afford
greater heating power to boiler furnaces by burning the fuel in such a manner that
at the front part of the furnace where the fresh fuel is introduced this is in great
measure only subjected to a distilling process so as to give off its volatile constituents,
which in passing forward over the inner part of the fuel in a high state of
incandescence, there enters into combustion with the highly heated air supply passing
up through the fuel.
We effect this object by supplying the fuel on the front part of the furnace bars or
on the dead plate with only a very limited quantity of air, by preference heated to a
considerable degree, so as only to maintain a thin layer of the fuel in a state of
incandescence on the fire bars or dead plate, the heat from which layer effects the
distillation of the volatile constituents from the thick layer of fresh fuel above it.
This limited supply of air to the front part of the fuel may be effected by providing
immediately beneath the front bars of the furnace a plate, so arranged that the air
supply to the furnace enters helow such plate and travels forward to the end of the
same, where the greater part passes up through the back part of the furnace bars
while a smaller portion returns and passes in a thin layer through the narrow space
between the said plate and the bottom of the furnace bars, and, becoming highly
heated, passes up through the furnace bars above the plate. A door or valve may be
provided in front through which a regulated quantity of air may also be allowed to
enter directly inio the narrow space between the bars and the plate, or the plate may
be made with opening and closing louvre blades or with openings closed by slides for
this purpose. Or the portion of the air supply for the front part of the grate may be
admitted entirely from the front end into the said narrow space while the air supply
to the back part of the grate passes underneath the plate. Or the front part of the

page_text: grate may be made as a dead plate having narrow openings through which the air
entering the said narrow space, between the dead plate and the plate below, rises
among the fuel. In this arrangement the dead plate and the plate below may bo
made in one casting constituting a hollow dead plate.
Fig. 1. of the accompanying drawings shews a longitudinal section of one arrange-
ment of a boiler furnace constructed according to this invention, Fig. 2. shews a part
front view and a part transverse section of the same.
A is the before mentioned plate, fixed at a small distance from the undersides of
the front part of the furnace bars, and extending right across the furnace, being
supported by angle irons B B, on the sides of the furnace. The space between the
plate A and the bars is closed by a flap C, hinged either to the plate A as shewn or
to the front of the furnace, so that by opening this flap more or less, a certain
quantity of air may be admitted directly into the space, while when it is closed, the
whole of the air supply enters beneath the plate A and, after passing beyond the
inner end thereof, part of it rises up through the back part of the grate bars, while a
smaller portion passes backward in the space between A and the front part of the
grate bars, becoming highly heated and then rising up between the bars to enter into
combustion with the thin layer of incandescent fuel on the bars. The air supply
passing up through the back part of the grate bars, being more than will enter into
combustion with the solid fuel there situated, will partly pass through the same,
becoming highly heated, and will impinge upon and enter into combustion with the
combustible gases that are passing forward from fuel on the front part of the furnace.
In the arrangement shewn in section and front view at Figs. 3 and 4, the plate A
is not fixed, but can he slid in and out upon the angle iron bearings B, being
provided with a handle E for this purpose. By this means the effect of the plate
upon the combustion can be modified according to the position of the plate. The
flap C is in this case fixed on the furnace front.
The heating capacity of an existing furnace may be further increased by forming
an extension as indicated by the dotted lines at so that the part extending from
the commencement of the bars to the end of the extension then serves as a dead plate
for the reception of the fresh fuel that is subjected to the distilling operation, the
dead plate being formed either with or without holes for the passage of air through it
from the space between it and the plate A.
Figs. 5 and 6 shew perspective views to an enlarged scale, of the plate A, formed
with an opening F, which can be more or less closed by a slide moved by a
handle G so as to admit more or less air from below into the space between the plate
and the bars.
Figs. 7 and 9 shew respectively a longitudinal section and a cross section of an
arrangement in which the plate A is formed into a hollow or double dead plate, the
upper surface A being formed with slits or perforations as shew in plan at Fig. 8.
In this arrangement the whole of the air supply to the front part of the furnace is
admitted through the flap C; a similar opening closed by a flap might however also
be provided at the inner end of the hollow dead plate, the flap being worked by a
handle from the front.
Fig. 10 shews a longitudinal section and Fig. 11. a plan of an arrangement in
which the box-shaped dead plate A is formed to carry the front bars H, the air supply
to which is regulated by the flap C.
Fig. 12 shews a vertical section of a locomotive fire box with this invention applied
thereto, the plate A being in this case arranged to be slid upon angle iron supports I
by means of the handle E either into the position shewn, or into the opposite position
on the other side of the fire box, according to the direction in which the engine is
travelling; the fresh fuel must in this case be thrown either on the front part or on
the back part of the grate, according to the position of the plate A.
Or instead of arranging the plate A to shift as described, it may be fixed in the
position under the front end of the grate, and a second plate A2 Fig. 13 be fixed
below it, extending from the back end of the fire box just above the flap J to within
a certain distance of the front end, so that when the engine is running forward the

page_text: air supply entering through J passes first forward underneath A2 and then back
again underneath A into the furnace, while on running backward the air supply
entering through the flap K passes directly underneath A to the furnace.
Or in place of the fixed plate A2 the flap J, instead of opening outwards as usual,
may be arranged to open inwards, and be considerably extended in length, as shown
in dotted lines at Fig. 13, so that when raised it will, serve in lieu of the plate A².
Fig. 1 shews the invention applied to a vertical steam boiler, the opening with
flap being omitted in this case.
Having now particularly described and ascertained the nature of this invention and
in what manner the same is to be performed we declare that what we claim is :-
1. Enclosing the underside of the front part of a boiler furnace by a plate in such
manner that the air supply to the inner part of the furnace passes beneath such plate
while a small portion of the air supply is made to pass into the narrow space between
the said plate and the furnace bars or perforated or slotted dead plate, substantially
as herein described.
2. In boiler furnaces constructed as set forth in the preceding claim, arranging the
plate A in combination with a flap C for admitting more or less air from the front
into the space between the plate and the underside of the bars, air being at the same
time admitted into such space at the inner end of the plate A substantially as herein
described with reference to Figs. 1. to 4 of the drawings.
3. Constructing the plate A to be slid more or less from beneath the furnace bars,
substantially as described with reference to Figs. 3 and 4 of the drawings.
4. Constructing the plate A with openings closed by a slide or slides or with
moveable louvre blades for the admission of a regulated quantity of air into the space
above the plate, substantially as herein described with reference to Figs. 5 and 6.
5. Constructing the plato A as a hollow or box-shaped dead-plate, having a
regulating flap at one or both ends for the admission of air and perforations or slits in
the upper surface for the passage of the air into the fuel, substantially as herein
described with reference to Figs. 7, 8 and 9 of the drawings.
6. The modified arrangement of hollow dead plate referred to in the preceding
claim in which it is made to carry the front bars of the furnace substantially as herein
described with reference to Figs. 10 and 11 of the drawings.
7. The application of the plate A referred to in the first claim to the furnaces of
locomotive boilers wherein the said plate is capable of being shifted from the one side
to the other side of the fire box, according to the direction in which the engine is
running substantially as herein described with reference to Fig. 12 of the drawings.
8. The combination in a locomotive engine of a plate A extending from the front
of the furnace beneath the bars, towards the back, with a second plate A² or flap J,
extending from the back of the furnace, beneath the plate A, towards the front,
substantially as herein described with reference to Fig. 13 of the drawings.
Dat his 3 day of twil 1887
ABEL & IMRAY,
Agents for the Applicants.