An Improved Device for Equalizing the Forced Draught for Steam Boiler. Destructor, or other Furnaces.
Year: 1899

page_text: Date of Application, 12th Sept., 1899-Accepted, 28th Oot.,
1899
An Improved Device for Equalizing the Forced Draught for Steam
Boiler. Destructor, or other Furnaces.
We, ROBERT GOSLING, Engineer, and THE IMPROVED PATENT FORCED DRAUGIFT
FURNACE SYNDICATE, LIMITED, both of 73, Queen Victoria Street, in the City and
County of London, 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 relates to an improved device for equalizing the forced draught
for steam boiler, destructor, or other furnaces, and has for its object the promo-
tion of an uniform combustion of the fuel by a more perfect and equal distribution
of the draught under the area of the fire."
In forced draught furnaces as ordinarily constructed the air is forced in by an
injector simply to the underpart of the grate area which is closed in so as to
form a chamber. The injector usually consists of a nozzle through which a jet
of steam is injected into a vent with an air space surrounding the said nozzle,
the jet of steam forcing in a considerable amount of air to the chamber below
the fire grate area.
The space beneath the fire bars is thus charged with air and vapour at a pres-
sure and, it is found, causes the air to blow through to a great extent in the
weakest part of the fire and that which offers the least resistance, increasing the
rapidity of combustion at that point to the detriment of the remainder of the fire,
and frequently resulting in the fire being blown right through, the unconsumed
fuel being carried into the flue thereby causing a vent, while the heat is so
intense at that point as to seriously injure the fire bars.
To overcome these drawbacks we provide the furnace with several air tubes each
preferably closed at one end and provided with perforations on the upper side
thereof.
These air tubes are placed near the under side of the firebars and air is forced
into them in any of the ordinary and well known manners preferably by 'means
of an injector of a suitable pattern. By this means the air is impinged upon every
part of the fire, the draught is more equally distributed, and the fuel is uniformly
consumed thus effecting a large saving in the cost of production of steam and
entirely preventing unconsumed fuel being carried away from the fire.
Referring to the accompanying drawings:
Fig. 1 is a longitudinal section of a portion of a furnace with our improvements
applied thereto.
Fig. 2 is a sectional elevation of the front of the furnace and Fig. 3 is a hori-
zontal section of one furnace and showing the arrangement of air tubes.
A furnace a is provided with the usual door 6 for the introduction of the fuel
_and_with_firebars_c_placed closely adjacent to each other. Beneath the said fire-
bars are placed tubes d perforated in their upper faces as shown and fitting on
the flanged orifices e in the front plate f; and into these orifices are inserted
injector nozzles g connected to the steam space of the boiler through the casing h
pipe i cock junction bracket m and pipe n. The inner tubes & are preferably
shorter than the outer ones in order to insure an increased supply of air to the

page_text: front of the fire grate. The steam issuing from the nozzles g draws air through
the annular spaces o and forces it through the perforations p against the under-
side of the fire.
A door g is provided in the front plate f to allow a space for a natural draught
for the purpose of lighting the fires or at other times, when a forced draught is
not required, to afford a space for the removal of any fine ash or other debris
which may have fallen through the interval of the fire bars from the furnace,
Having now particularly described and, ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:-
:
1. In a forced draught apparatus for furnaces, the combination with the fur-
nace of a series of air tubes beneath the fire bars and having holes in the upper
faces thereof, nozzles introduced into the ends of said tubes for the injection of
steam and air spaces surrounding said nozzles, substantially. as described and
illustrated.
2. A device for equalizing the forced draught for steam boiler, destructor, or
other furnaces arranged constructed and operating substantially as described
and illustrated.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.