Improvements in and connected with Steam-boiler and other Furnaces.
Year: 1892

page_text: Date of Application, 18th Mar., 1892-Accepted, 23rd Apr., 1892
COMPLETE SPECIFICATION.
Improvements in and connected with Steam-boiler and other
Furnaces.
I, ARCHIBALD MCARTHUR, of 11 Blair Terrace, Dempster Street, Greenock,
in the County of Renfrew, North Britain, 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, that
is to say:
My said invention has for its object by improvements in and connected with
steam-boiler and other furnaces, to obtain economy of fuel, and to prevent smoke.
In carrying out my invention I may employ any suitable known arrangement of
mechanical stoker or fuel feeder, but I prefer to use one of simple construction and
not liable to derangement. The fuel is introduced by the stoker into the outer end
of a kind of retort or oven which is made preferably of firebrick or of iron lined
with firebrick, and which projects from the outer end of the furnace. The inner
end of the retort is open to the furnace above the ordinary grate level; and as the
fuel moves gradually inwards by the pressure of the fresh fuel which is being
continually pushed in, it passes from the inner end of the retort on to a set of fire
bars. The fire bars which may be connected together transversely are arranged on
a transverse shaft or otherwise in a manner to allow of their front ends being inclined
downwards for the convenient removal of ashes and for cleaning purposes.
A partial combustion of the fuel is effected in the retort with the aid of air
forced in under pressure at or near the outer end; and at the upper part of the
retort near the inner end valved openings are provided for admitting a regulated
supply of air for completing the combustion within the furnace.
An example of my improved furnace apparatus is delineated upon an accom-
panying sheet of explanatory drawings, of which Figure, 1, is a front end elevation,
and Figure, 2, a longitudinal vertical section, showing the application of the
apparatus to a horizontal cylindrical steam boiler of common type.
Outside of the boiler, B, I fix against the end of the furnace, F, above the grate
bars, G, a kind of oven or retort, R, of firebrick, which has adapted to its outer
end a casting, C, forming the lower part of the stoker, or mechanical fuel feeding
apparatus. The bottom of the inner end of the retort, R, is supported on a
casting, D, which is bolted to the end of the boiler, and which has bolted to it tie
rods, E, which secure the casting, C, at the outer end of the retort, at its lower
part, other tie rods, H, securing the upper part of the casting, and the tie rods, E, H,
and casting, C, together holding the retort, R, in position. Above the casting, C,
and extending back over the retort, R, is the hopper, J, of the stoker, the bottom
of this hopper being provided with a slide, K, for regulating the descent of the fuel
into the casting, C. In the casting, C, there is fitted to slide a pusher, L, which is
acted on by a rod and spring, M, jointed to a lever, N, on a rocking shaft, P,
carried by brackets fixed to the casting, C, and to the hopper, J. The rocking
shaft, P, is worked from a rotating shaft, Q, above, driven in any convenient way,
and having on it an eccentric, S, a rod, T, from which is adjustably connected to a
lever, U, on the end of the rocking shaft, P.
For the partial combustion of the fuel in the retort air under pressure is supplied
by a pipe, V, fitted with a regulating valve, to a cavity, W., in the lower part of
the casting, C, and finds its way into the retort through passages, X. In the outside
of the casting, C, there are holes to which covers, Y, are fitted to be opened for
inspecting the interior of the retort or for introducing a poker if required. The
partial combustion within the retort, R, promotes the evolution from the coal of
its more volatile constituents, the volatilised matters being compelled to pass

page_text: through and over the highly heated coal at the inner end of the retort, and on the
grate bars, G. To complete the combustion of the volatilised matters air is
admitted by openings, Z, formed in the upper part of the retort, R, near its inner
end, the quantity thus admitted being regulated by means of sliding plates fitted to
the outer sides of the openings.
The fire bars, G, when in their normal position as shown in Figure, 2, have a
downward inclination towards the inner end of the furnace space. They are
carried on a transverse shaft, 8, and being fixed together transversely they can be
rocked on the shaft, 3, so as to lower their front ends for removing ashes or for
cleaning or other purposes. A socket, 4, is formed on the front end of the middle
bar, G, to receive the inner end of a long bar or lever by means of which the set
of grate bars can be turned down; and hand bolts, 5, are provided for locking the
grate bars in their normal position. The front end of the ashpit, A, has applied to
it a door or pair of doors, 6, which may be adjusted to admit more or less air as
required. The ashpit space, A, is in practice closed at the inner end by ashes
which fall off the inner and lower ends of the grate bars, G.
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-The improved combination of parts of and connected with steam-boiler and
other furnaces, substantially as hereinbefore described and as shown in the
accompanying drawings.
2-The combination with a steam-boiler or other furnace, of a retort or oven
joined to the front end thereof, the said retort or oven being constructed, fed with
fuel, and supplied with air substantially as hereinbefore described.
3-In a retort or oven for the preliminary treatment of fuel in connection with a
furnace providing for the supply of air under pressure at the outer end thereof for
partial combustion a further supply of air being admitted at or near the inner end
substantially as hereinbefore described.
4-ln a furnace having a retort or oven for the preliminary treatment of the
fuel joined to its front end, a set of grate bars inclined downwards towards their
inner ends in their normal position and arranged so that they can be rocked into
the reverse position substantially as and for the purposes hereinbefore described.
Dated this Seventeenth day of March 1892.
EDMUND HUNT,
Applicant's Agent.