Improvements in and relating to Boiler Furnaces.
Year: 1891

page_text: Date of Application, 29th Aug., 1891-Accepted, 3rd Oct., 1891
.
COMPLETE SPECIFICATION.
Improvements in and relating to Boiler Furnaces.
I, JOHN TATE, Manager to the Hematite Iron & Steel Company (Limited).
Workington, Cumberland, 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 ensure more complete combustion of the fuel
consumed in boiler furnaces and to that end it consists in the provision of improved
means whereby the heat absorbed by the brickwork of the boiler setting, and
thence radiating to the earth or atmosphere, is intercepted and utilized for heating
the air supplied to the furnace, and in the construction of the furnace front and
connections for admitting such heated air to furnaces arranged to burn gaseous, solid
or liquid fuel.
In the accompanying drawings, which illustrate my invention,
Figures 1, 2 and 3, are respectively a sectional side elevation, sectional plan,
and transverse vertical section, showing the arrangement for heating air and
supplying it to a number of boiler furnaces adapted to burn gaseous fuel such as
blast furnace gases, Figure 1 being a section at the lines 1-1 in Figure 2. which
is taken as at the lines 2-2 in Figure 3, whilst Figure 3.is a section taken as at
the line 3-3 in Figure 2.
Figure 4 is a sectional elevation of the boiler front.
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Figure 5 is a sectional elevation showing the construction of the boiler front and
hot air casing thereon for a furnace adapted to burn solid fuel,
Figure 6 a sectional plan of the same and
Figure 7 a vertical section at right angles to Figure 6 of the hot air admission
casing.
Referring particularly to Figures 1 to 4 of these drawings, the boiler, which is of
ordinary construction and has one or more flues, is supported upon brickwork
setting or arched walls A, A', which form the usual flues leading from the furnace
to the main chimney flue B. In the spaces between these walls A, transverse
walls C are built having openings D formed in them close to the one wall A, and
the opposite wall A alternately so as to form a tortuous or zig-zag passage for air
which enters from a main air flue E, and after traversing this passage and being
brought in close contact with the walls A so as to absorb waste heat from them flows.
upwards through passages F into a tortuous passage similarly formed by building.
transverse walls with openings D' in them between the walls A¹ A of the upper
flues. After being highly heated in traversing the upper passago, the air isidia-
charged through nozzles & into casings H in front of each furnace fluetand forming.
the furnace mouth whereinto the gaseous fuel is also led, the discharge nozzles
being preferably fitted to extend through the gas supply pipes I at the points where
they enter the casing H, but they may be arranged to discharge the heated air
outside or around the gas supply pipes.
Dampers Jare provided to regulate the admission of hot air to the furnace
through the nozzles G, and the gas supply pipes I,, are also provided with valves or
dampers K.
The air being raised to an extremely high temperature by absorption of the
waste heat from the boiler setting in traversing the tortuous passages formed
therein, and the supply being regulated, perfect combustion of the fuel admitted to
the furnace is ensured with resulting economy and absence from smoke.
In lieu of the arrangement of parallel walls C C¹, checker work such as is
employed in heating air for regenerative furnaces or for hot blast stoves may be
formed in the spaces between the walla A A' of the boiler setting to heat the air

page_text: passing throngh said spaces. In the outside supporting walls of the outside flues of
a range of boilers, the air passage is preferably carried back and forth longitudinally
as indicated at the right hand end of Figure 3, in close proximity to the inside
wall A which is made as thin as possible, whilst the outside wall may be of extra
thickness to prevent cooling of the air by radiation.
In applying the invention to furnaces burning solid fuel as indicated at
Figures 5, 6 and 7, the air heated in the manner above described by traversing
tortuous passages or checker work formed in the boiler setting is discharged
through a double casing L, fitted in front of the furnace flue or flues.
The inner portion of the casing is composed of a semi-circular box L', in front of
each furnace extending upwards from the furnace bars M to the crown of the
furnace and downwards to form an ash outlet at L. The casing L is divided by a
web into upper and lower compartments to both of which the heated air is admitted
and the hot air passes into the furnace from the upper compartment through a slit
or orifice N formed between the box L' and the furnace mouth, the said slit N,
being tapered or made narrower next the main air inlet than at the opposite side of
the furnace in order to effect proper distribution of the air over the fuel on the fire
grate. The heated air flowing into the under compartment of the casing L, passes
through orifices in a plate separating it from the ash box and provides the requisite
air supply through the fire grate to the mass of fuel thereon, dampers P being
provided to regulate the air admission both above and below the fire grate.
In this case the orifices on the side farthest from the air inlet are purposely made
larger or more numerous than those on the near side to ensure suitable distribution
of the air supply under the fire grate.
Suitable firing doors N' and ash doors O are formed in the casing L for each
furnace.
Arrangements similar to those above described for heating air and admitting it to
the furnace may be employed in cases where liquid hydro-carbon or other liquid
fuel is used, and they are also applicable to other forms of boiler than that
represented in the drawings..
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. In combination with a boiler furnace the provision of a tortuous passage or
checker work built in the boiler setting and arranged to heat air led through it to
supply the furnace substantially as described.
2. In combination with a gas fired boiler furnace the arrangement of air nozzles
led through or around the gas supply pipes in conjunction with means for heating
the air and regulating the supply to the furnace substantially as described.
3. In combination with a boiler furnace for burning solid or liquid fuel the
casing L fitted in front of the furnace and arranged to control the supply of heated
air above and below the fire grate, substantially as described.
Dated this Timenty eighth da of 1901
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.