Improvements in and connected with Steam-boiler Furnaces.
Year: 1890

page_text: Date of Application, 6th Nov., 1890
Complete Specification Left, 30th July, 1891-Accepted, 5th Sept.. 1891
PROVISIONAL SPECIFICATION.
Improvements in and connected with Steam-boiler Furnaces.
We, JOHN FINLAY RANKIN, and MATTHEW RANKIN, of the Eagle Foundry,
Greenock, in the County of Renfrew, North Britain, Engineers, do hereby declare
the nature of this invention to be as follows, that is to say :-
Our said invention has for its object to apply forced draught to steam boilers in
an improved, economical, and satisfactory manner, and by means of apparatus of a
simple kind, which being devoid of expensive and projecting casings in front of the
fire doors, does not like such casings interfere with the thorough and convenient
stoking and cleaning of the fires. The damages to which such casings are liable
from changes of temperature are also avoided by our apparatus.
Our improvements are designed for application to prevalent types of marine
boilers; but they are also applicable to any steam boilers in which there are
combustion chambers, that is chambers in which the combustion of the volatilised
products of the fuel is completed after the said products leave the grates.
In carrying out our invention in the case of a single-ended boiler that is a boiler
having one or more internal furnaces at its lower part, one or more combustion
chambers at the back of the furnace or furnaces, and return tubes from the upper
part of the combustion chamber or chambers, we lead the air from the blower or
forcing apparatus into a casing at the back of the boiler; and this casing communi-
cates with pipes which extend forward from it across the lower part of the
combustion chamber to the ash pits of the furnaces, there being one or more of the
pipes for each furnace. In the upper part of each tube there are a number of
orifices up through which jets of air pass into the combustion chamber to assist in
completing the combustion therein. At the front ends of the pipes simple valves
are fitted adjustable by means of rods extending outside the front of the boiler, for
the purpose of regulating the quantity of air entering the ash pits, the front ends
of which are closed except when removing ashes. Provision is also made for
injecting some air above the fuel at the front end of each furnace, by means of a
pipe with a regulating valve or stopcock, and supplied with air from the ash pit, or
in any other convenient way.
In the case of a double-ended boiler with one or more combustion chambers
in the middle, the forced-air casing is arranged below the boiler, and communi-
cates through the bottom of the boiler with the middle parts of internal air pipes
the opposite ends of which communicate with the ash pits of opposite furnaces.
A separate regulating valve is provided for each ash pit; and the pipes are made
with orifices for delivering jets of air into the combustion chamber or chambers.
In any application of our invention instead of employing internal air pipes as
herein before described, the bottom part of each combustion chamber may be covered
by a partition so as to form an enclosed space into which the forced air is admitted,
and from which it issues through jet orifices up into the combustion chamber, and
into the ash pit or pits through regulating valves. And where convenient, in the
cases of single-ended, double-ended, or other boilers, an inlet for the forced air may
be arranged through the bottoms of the boilers at any points between the outer
ends of the boilers and the backs of the combustion chambers, the internal air pipes
or passages being arranged to supply air both below the grates and into the
combustion chambers.
1000

page_text: COMPLETE SPECIFICATION.
Improvements in and connected with Steam-boiler Furnaces.
We, JOHN FINDLAY RANKIN, and MATTHEW RANKIN, of the Eagle Foundry,
Greenock, in the County of Renfrew, North Britain, Engineers, 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, that
is to say :-
Our said invention has for its object to apply forced draught to steam boilers in
an improved, economical, and satisfactory manner, and by means of apparatus of a
simple kind, which being devoid of expensive casings in front of the fire doors, does
not like such casings, interfere with the thorough and convenient stoking and
cleaning of the fires. The damages to which such casings are liable from changes
of temperature are also avoided by our apparatus.
Our improved arrangements are designed for prevalent types of marine boilers,
but our improvements are also applicable to any steam boilers in which there are
combustion chambers, that is chambers in which the combustion of the volatilised
products of the fuel is completed after the said products leave the grates.
We hereunto append a sheet of explanatory drawings to be hereinafter referred
to, and showing examples of the application of our improvements.
Figures, 1, 2, and 3, are vertical sections, and Figure, 4, is a partial end elevation.
In these drawings the same reference letters are used to mark the same or like
parts wherever they are repeated.
In carrying out our invention according to one modification, in the case of a
single-ended boiler, such as is shown in Figure, 1, that is a boiler having one or
more internal furnaces, A, at its lower part, one or more combustion chambers, B,
at the back of the furnace or furnaces, A, and return tubes, C, from the upper part
of the combustion chamber or chambers, B, we lead the air from the blower or
forcing apparatus into a casing, D, at the back of the boiler; and this casing, D,
communicates with one or more pipes, E, which extend forward from it across the
lower part of the combustion chamber, B, to the ash pits, F, of the furnaces, A. In
the upper part of each pipe, E, there are a number of orifices up through which
jets of air pass into the combustion chamber, B, to assist in completing the com-
bustion therein. At the front end of each pipe or tube, E, a simple valve, G, is
fitted, adjustable by means of a rod, H, extending outside the front of the boiler,
for the purpose of regulating the quantity of air entering the ash pit, F, the front
end of which is closed by a door, J, except when removing ashes, at which times
the valve, G, is closed. Provision is also made for admitting some air above the
front ends of the grate bars, K. This may be done simply by means of holes in
the dead plate, L, air from the ash pit, F, passing through the holes up into a space
between the fire door, M, and the usual inner battle plate, N, and finding its way
round the latter into the furnace, A. Or a pipe with a regulating valve or stop-
cock may be provided for supplying air above the grate bars.
It may be found preferable in practice to have the air-jet orifices in a partition
plate shown by dotted lines, P, placed across the combustion chamber, B, at a
higher level than the top of the pipe, E. And instead of having one or more
comparatively large pipes, E, fixed across the back water space, Q, in flanged
openings as shown in Figure, 1, the air may enter from the casing, D, through
a number of small short tubes, R, as shown in Figures, 2, and 3, into a partitioned
space, S, in the lower part of the combustion chamber, B.
In the case of a double-ended boiler such as is shown in Figure, 3, with one or
more combustion chambers, B, in the middle, the forced-air casing, D, is arranged
below the boiler, and communicates through the bottom, by preference by a
sufficient number of small tubes, R. with the middle parts of internal air com-
partments, S, the opposite ends of which communicate with the ash pits, F, of

page_text: opposite furnaces. A separate regulating valve, G, is provided for each ash pit,
and the top partitions of the air compartments are made with orifices for delivering
jets of air into the combustion chamber or chambers, B.
In any application of our invention instead of employing internal air pipes as
hereinbefore described, the lower part of each combustion chamber, B, may be
covered by a partition, such as, P, so as to form an enclosed space or com-
partment into which the forced air is admitted, and from which it issues through
jet orifices up into the combustion chamber and into the ash pit or pits through
regulating valves. And where convenient, in the cases of single-ended, double-
ended, or other boilers inlets for the forced air may be arranged through the
bottoms of the boilers at any points between the outer ends of the boilers and the
backs of the combustion chambers, the internal air pipes, passages, or compart-
ments, being arranged to supply air both below the grates and into the combustion
chambers.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
In steam boilers worked with forced draught, the improved arrangements with
which the forced air is supplied to pipes or air compartments in the lower parts of
the combustion chambers, such pipes or compartments having orifices at their upper
parts for the issue of jets of air into the combustion chambers, and also having
valved openings through which regulated quantities of the air may be supplied
under the grates, substantially as hereinbefore described.
Dated this Twenty-ninth day of July 1801
EDMUND HUNT,
Applicants' Agent.