Improvements in Regenerative Furnaces, and Fans for Inducing Draught therefor.
Year: 1895

page_text: Date of Application, 9th July, 1895
Complete Specification Lelt, th Apr., 1896-Accepted, 9th July, 1896
PROVISIONAL SPECIFICATION.
Improvements in Regenerative Furnaces, and Fans for Inducing
Draught therefor.
GEORGE FREDERICK PRIESTLEY Hope Street Mill Halifax and WALTER
SCOTT BANCROFT Hope Street Mill Halifax Engineers, do hereby declare the
nature of this invention to be as follows:-
This invention relates to furnaces especially for burning town's refuse and low
class fuels, and consists of a series of cells or furnaces running parrallel to each
other and connected to one or more flues to carry away the products of
combustion.
The furnaces are constructed with a reverberatory arch above the fire grates, the
said arch extending beyond the firebridges and forming a chamber between the
firegrate & flue. In this chamber is built a mass of firebrick, known in the trade
as chequer" work.
The front side of this brickwork facing the fire is pierced with a series of
parrallel holes, forming a series of small flues communicating between the fire and
the flue beyond and thro' which the products of combustion pass, in their passage
thro' the above holes, imparting heat to this mass of brick work.
At right angles to the gas passages, are a series of vertical similar openings thro'
which the primary air supply to the furnaces pass downwards. The heated air on
reaching the base of this brickwork is led into larger horizontal channels-these
communicate with the walls forming the sides of the furnaces, which are built with
a cavity within them, thro' which the hot air finds its way to suitably place.l
distributing valves both above and below the firegrates, thus supplying the furnaces
with heated air.
The furnaces are preferentially arranged in sets of four, each individual furnace
running parrallel with its neighbour. Along the back of these furnaces is a main
flue and bye pass flue and parrallel with these flues is placed a suitable steam
generator or boiler for utilizing any waste heat from the products of combustion.
A complete battery of furnaces consists of 2 sets of 4 furnaces each, placed back to
back with the boiler between.
In order to promote combustion of the refuse, we employ induced draught in
preference to steam blowers or forced draught.
The fan we employ for this purpose is specially constructed to withstand the
high temperature gases in which it works, and consists of a steel plated fan-casing
built in cellular form, forming a space or jacket thro' which water is continually
circulating by means of a pump. The fan proper is constructed as follows. The
main shaft is bored throughout its length and the end to which the fan blades are
attached is swelled up to form a larger diameter than the body part of the shaft
itself, somewhat similar to a shaft coupling.
Inside this larger diameter, is bored an annular space communicating with the
hole in the shaft. A series of radial holes are bored in this coupling or boss, into
which pipes are screwed radially.
Secured to the faces of the boss, by screws or other suitable means are two steel
disc plates, the distance between the plates representing the thickness of the boss,
and intermediate between the two plates are the radial pipes mentioned above.
The outer edges of the two steel plates are joined together by a channel irou hoop

page_text: suitably rivetted to the plates, the whole thus forming an annular water tight
steel plate disc.
-
At right angles to this disc are rivetted a suitable number of cellular steel plate
fan blades, these are constructed of two suitably shaped flat steel plates, with
distance picces rivetted between them. The said distance pieces being channel
iron, bent to the outside contour of the fan blades, and rivetted securely together.
These blades are also rivetted to the disc by angle irons, and are further strengthened
and supported by a star wheel having ribbed arms which support the outer edges
of the fan blades, the wheel being provided with strong boss and securely keyed
on to the fan shaft.
Communication between the fan blades and the disc is obtained thro' a series of
small holes in the face of the disc, and communicating with the annular space in the
blades.
To maintain a perfect circulation of water thro' the fan, we employ special
means, as follows.
The outside plate of the steel disc i.e. the opposite one to which the fan blades
are rivetted and at or near the shaft, we secure a cast iron hollow disc with
an extension piece, enclosing the shaft, and leaving an annular space between it and
the shaft.
This extension piece is turned on the outside and fitted with a gland and stuffing
box, to which is attached an outlet pipe, for the passage of the steam and water.
The passage of the water thro' the fan is as follows.
Communication is made between the pump and the extreme outer end of the fan
shaft by means of a suitable stuffing box-the water passing along the fan shaft to
the coupling end is immediately thrown out of the radial arms by centrifugal force,
filling the steel disc, and fan blades. The steam generated in the fan blades by the
impinging heat of the flue gases, has always a tendency to gather at and escape at
the smaller diameter of the fan or towards the shaft. The heavier body of water,
by reason of the centrifugal force always remaining solid at the outer or larger
diameter. The stean: is collected inside the cast iron disc encircling the fan shaft,
and is conducted thro' the nose piece & stuffing box to the outlet pipe from whence
it escapes.
A constant circulation of water is thereby maintained thro' the fan, and
also the fan casing.
Dated this 8th day of July 1895.
GEORGE F. PRIESTLEY.
WALTER SCOTT BANCROFT.
Improvements in Regenerative Furnaces, and Fans for Inducing
Draught therefor.
GEORGE F. PRIESTLEY Hope Street Mills, Halifax Engineer, WALTER SCOTT
BANCROFT Hope Street Mills, Halifax 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 :-
This invention relates to furnaces especially for burning town's refuse and low
class fuels, and in order that our invention may be better understood, reference is
had to the accompanying drawings, in which
Fig. 1 represents a longitudinal cross section thro' the furnace and flues;
Fig. 2 & 3 drawings of the special fan used for inducing the draft.
The refuse or low class fuel to be burned is introduced into a hopper 1, placed
above the dead plate of the furnace 2. This hopper 1 is made of a suitable given
capacity, so that the fuel is introduced on to the dead plate 2 in a measured
quantity and the fires are not overcharged with green fuel. The low end of the

page_text: hopper is provided with a sliding shutter 3, which serves the double purpose
of introducing the fuel quickly on to the dead plate, and which when closed seats
the furnace and prevents the suction of cold air into the furnace.
From the dead plate 2, the refuse is raked on to the fire grates thro' doors 4, or
carried automatically by means of mechanically moved or self-feeding fire bars.
The fire bars 5, shewn on drawing are supported in one or more frames 6, which
frames are hinged at 7. By means of a quadrant 8, or other suitable mechanical
means, the bridge end of these bars can be lowered to the position shewn by the
dotted lines & the clinker or burnt, fuel ejected off the end of the bars into the
clinker pit 9. By this means the clinkering and clearing of the grates is
accomplished easily and in the least possible time.
The furnace front 10 is one of a series, extending along the range or battery,
according to the capacity of the plaut, and Fig. 1 represents a cross section thro' a
single furnace. The fronts 10 are of cast or wrot iron, to minimise air leakages
thro' the brickwork, and also to hold the brickwork together by means of tie rods
and bolts 11.
66
The furnaces proper, consist of a series of cells almost similar to an ordinary
brick kiln, the tops of the cells are constructed with reverberatory arches 12,
running from back to front. These reverberatory arches spring from side walls 13,
which form the partition walls between the furnaces. At or near the firebridge in
each furnace is built a mass of brick work 14, technically known as chequer
work," this brickwork, by a series of small horizontal holes 15, forming a series of
small flues, thro' which the products of combustion pass to a flue 16. This
'chequer work" is separate and distinct from the furnace chamber proper and can
be renewed when burnt out without disturbing the side walls or reverberatory
arch.
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In passing thro' the series of small horizontal flues, any noxious gases arising
from the burning fuel are rendered innocuous by passing thro' this heated
mass of brickwork.
A number of vertical pipes 17, are also built into this " chequer" work
alternately between the horizontal flues, the bottom ends of these tubes are
preferably bolted to horizontal tubes 18, which lead into the hollow spaces of the
side walls 13.
The gases of combustion passing along the flue 16 may be utilized in any suitable
manner for steam raising purposes.
In the accompanying drawing is shewn a Lancashire type of boiler 20 for this
purpose. The gases passing along the central flue 21, side flues 22, and thence to
fan, and main flue.
An essential part of our invention for promoting perfect combustion is the use of
a primary hot. air supply to furnaces, which is obtained in the following mauner.
Through grates 25, placed on the top of furnaces, the air at ordinary temperature
is sucked by means of fan, into chamber 26.
This chamber is common to the vertical tubes 17, and in passing from the top to
the lower or branch tubes 18, the heat from the "chequer "work is transmitted to
the air supply passing thro' the pipes. The distribution of the air to the gates or
valves 27, is accomplished by building the walls 13 with a hollow space. The
gates 27 are preferably placed both above and below the fire grates, thereby giving
complete control to the primary air supply.
For the convenient removal of the clinker, the pit 9 is preferably constructed
with an inclined floor fitted with door 28, and subway 29.
In order to promote combustion of the refuse, we employ induced draught in
preference to steam blowers or forced draught. The fan we employ for this
purpose is specially constructed to withstand the high temperature gases in which
it works & is shewn in detail on Figs. 4 and 5.
The fan shaft 30 is preferably made hollow and of any convenient length for
driving by belt or other means. A flanged coupling 31 at or near the end of shaft
with radial boles into which are screwed pipes 32, and which serve to lead water

page_text: into the fan disc 33. This fan disc is constructed of channel iron & circular plates
and at right angles thereto are placed the fan biades 34.
These blades are also constructed hollow, and the water is admitted from the fan
disc into the blades by means of a series of holes 35.
When the fan is revolving, the centrifugal force keeps the solid body of water to
the periphery of the fan and blades, and any steam generated by the impinging
heat of the flue gases naturally finds its way to the central portions of the fan and
thereby escapes by means of the holes 36, cover 37, and pipe 38 to the atmosphere.
A steam & water tight joint is provided at 39, and the cold water supply connection
at 40. The fan casing at 41 is also built cellular and a constant flow of water
passed thro' to keep the same cool.
Having now fully described the said invention, we claim as follows.―
1st. The use of a hopper of given capacity for gauging the quantity of fuel fed
on to the dead plate and provided with a sluice or shutter for sealing same.
2nd. The use of a hinged frame holding the grate bars, such frame capable of
being lowered at the bridge end for the easy ejection of the clinker.
3rd. The construction and use of a chamber or kiln constructed with a
reverberatory arch separate and distinct from the "chequer" work which is built
therein.
4th. The construction and use of a mass of "chequer" work directly behind the
firebridges of the furnaces, in which are placed a system of vertical iron pipes
running into longitudinal members for the purpose of heating the air supply.
5th. The construction & use of the cellular division walls, provided with air gates
or sluices both above and below the fire grates for the purpose of supplying the
furnaces with heated air.
6th. The employment of a specially constructed exhausting fan having a water
jacket both in disc & blades in conjunction with a hood for the removal of steam
and the hollow shaft water connection substantially as described.
7th. The construction & use of hopper, hinged frame firebars, chequer work, and
hot air tubes therein, cellular furnace walls and air gates, and water jacketed
exhausting fan in combination for burning refuse and low class fuels substantially
.as herein described.
Dated this 9th day of smil 1906
GEORGE F. PRIESTLEY.
W. SCOTT BANCROFT.