Improvements in Hollow Fire-bars for Furnaces.
Year: 1891

page_text: Date of Application, 19th Sept.; 1891
Complete Specification Left, 20th June, 1892-4ccepted, 23rd July, 1892
PROVISIONAL SPECIFICATION.
Improvements in Hollow Fire-bars for Furnaces.
I, CHARLES WHITFIELD of Union Street, Kettering in the County of
Northampton, Engineer, do hereby declare the nature of my said invention to be
as follows:-
These improvements refer to that class of hollow fire-bar employed for conveying
heated air to the ash-pits and combustion chambers of steam boiler and especially
marine boiler furnaces, in which the air to support combustion is supplied to the
furnace through such hollow bars by force draught but which bars by reason of
the great heat evolved are liable to be soon burnt out.
My improvements consist in constructing hollow fire bars with a double passage
formed therein as hereinafter described and whereby such bars are rendered more
effective in action and being kept cooler are found to be more durable than
heretofore.
In performing my invention I employ a fire-bar in which a double passage is
provided, a smaller passage near the top surface of the bar where the temperature
is the hottest, being nearest to the incandescent fuel, and at a lower level a larger
passage which at its back extremity opens into the ash-pit. The smaller passage
serves to convey the air from a hollow dead plate or air chamber and this in a
highly heated state either through a perforated or hollow bridge; whilst the larger
one serves to convey the air from the same hollow dead plate or air chamber into
the ashpit and thence between the fire-bars into the furnace.
Dated this 17th day of September 1891.
JOHN G. WILSON,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Hollow Fire-bars for Furnaces.
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 :-
These improvements refer to that class of hollow fire-bars employed for conveying
heated air to the ash-pits and combustion chambers of steam boiler and especially
marine boiler furnaces in which the air to support combustion is supplied to the
furnace through such hollow bars by forced draught but which bars by reason of
the great heat evolved are liable to be soon burnt out.
My improvements consist in constructing hollow fire-bars with a double passage
formed therein as hereinafter described whereby such bars are rendered more
effective in action and being kept cooler are found to be more durable than
heretofore.
In performing my invention I employ a fire-bar in which a double passage is
provided a smaller passage near the top surface of the bar where the temperature is
the hottest (being nearest to the incandescent fuel) and at a lower level a larger
passage which at its back extremity opens into the ash-pit. The smaller passage
serves to convey the air from a hollow dead plate or air chamber and this in a
highly heated state either through a perforated or hollow bridge whilst the larger
one serves to convey the air from the same hollow dead plate or air chamber into
the ash-pit and from thence between the fire-bars into the furnace.

page_text: And in order that my improvements may be more readily understood and carried
into practical effect I have hereunto annexed a drawing 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 transverse section of so much of the grate of a steam boiler furnace as
will show the application of my invention thereto and Fig. 2 is a transverse section
of the fire bars showing the formation of the double passage.
In accordance with my invention the fire bar is provided with an upper and lower
passage of which the upper passage (A) is smaller than the lower one (B) This
compound channel fire bar is connected to a hollow and enclosed dead plate (C)
arranged to receive air under pressure from any system of forced draught. The air
received into the hollow and enclosed dead plate (C) is forced along the two
channels (A) and (B) the air passing through the upper channel being discharged
through the hollow fire bridge (D) there to assist and complete the combustion of
the inflammable gases.
The air passing along the lower channel of the bar is
discharged into the ash-pit (which is enclosed) through the opening (E) at the rear
end of the ash-pit as indicated by the arrows and the air discharged finds its way up
through the spaces of the fire bars and promotes combustion on the grate.
I sometimes provide the hollow dead plate (C) with a discharge opening into the
ash pit controlled by the slide or shutter (F) operated by the knob (G) from the
front of the furnace.
It will thus be seen that the special feature of my invention is the compound
passage fire-bar receiving air from a hollow dead plate and passing it partly into
the ash-pit and partly into the combustion chamber behind the bridge.
Having thus particularly described and ascertained the nature of my said inven-
tion I wish it to be understood that I make no claim to a hollow fire-bar with either
single or double passage broadly but what I claim is.
In steam boiler and other furnaces the use and employment of a double passaged
fire-bar mounted and operating substantially as hereinbefore described and illustrated
on the accompanying drawing.
Dated this 13th day of June 1892.
JOHN G. WILSON,
Agent.