CERTAIN IMPROVEMENTS IN FURNACES APPLICABLE TO BOILERS FOR GENERATING STEAM OR OTHER PURPOSES
Year: 1868

page_text: LETTERS PATENT to Thomas Wrigley, of the Firm of Fielden,
Brothers, Todmorden, in the County of Lancaster, Manager, for
the Invention of "CERTAIN IMPROVEMENTS IN FURNACES APPLICABLE TO
BOILERS FOR GENERATING STEAM OR OTHER PURPOSES."
Sealed the 2nd February 1869, and dated the 27th August 1868.
PROVISIONAL SPECIFICATION left by the said Thomas Wrigley at
the Office of the Commissioners of Patents, with his Petition, on
the 27th August 1868.
I, THOMAS WRIGLEY, of the Firm of Fielden, Brothers, Todmorden,
in the County of Lancaster, Manager, do hereby declare the nature of
the said Invention for "CERTAIN IMPROVEMENTS IN FURNACES APPLICABLE TO
BOILERS FOR GENERATING STEAM OR OTHER PURPOSES," to be as follows:-
The Invention relates to that part of furnaces or fire-places called the
fire-bars, and is designed for the purpose of preventing smoke and
properly consuming the fuel and gases arising therefrom.
The improvements consist in the employment and use of fire-bars
arranged in three or more distinct lengths, each length being lower than
the one in front, each also being supported on plates or rails secured to

page_text: the sides of the furnace upon which they are capable of sliding. Each set
of bars terminates with slight projections on their under side which are
caused to rest upon or in close proximity to the next set of bars, and so
on to the bridge, thus giving a step-like formation to the grid of the
furnace, each plane or set of bars being capable of having a forward or
backward motion imparted to them by eccentrics and rods independent
from each other; the first set of bars being the highest are caused to
project out from the front of the boiler a distance that will admit of a
hopper being placed over them, which is secured to the front of the
boiler; this "hopper" is constantly kept filled with coal so as to prevent
any air passing into the furnace only underneath the grate. When the
furnace is ignited and in action the sliding bars are successively pushed
forward from the highest set to the lowest, after which they are all
withdrawn, commencing first with the lowest set. The intermittent
advance and return motion given to the bars causes them constantly to
carry and push forward the coal from the hopper onward towards the
bridge" during its passage, whilst being thus impelled; a thorough
consumption of coal and combustion of gas is effected, as the fire thus
formed commences with a green cr black fire and as it extends towards
the bridge it increases in brilliancy and heat, thus causing the gases
evolved from the green fuel at the front of the furnace to be thoroughly
consumed as they pass over the bridge into the flue.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Wrigley in the Great Seal Patent Office
on the 26th February 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
WRIGLEY, of the Firm of Fielden, Brothers, of Todmorden, in the
County of Lancaster, Manager, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-seventh day of August, in the
year of our Lord One thousand eight hundred and sixty-eight, in the
thirty-second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Thomas Wrigley, Her special license,
that I, the said Thomas Wrigley, my executors, adininistrators, and assigns,
or such others as I, the said Thomas Wrigley, my executors, adminis-
trators, and assigns, should at any time agree with, and no others, from

page_text: time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
FURNACES APPLICABLE TO BOILERS FOR GENERATING STEAM OR OTHER PURPOSES,"
upou the condition (amongst others) that I, the said Thomas Wrigley,
my executors or administrators, by an instrument in writing under
my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas Wrigley, do hereby
declare the nature of my said 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) :-
The Invention relates to that part of furnaces or fire-places called
the fire-bars or grates, and it is designed for the purpose of preventing
smoke and properly consuming the fuel and gases arising therefrom.
The improvements consist in the employment and use of fire-bars or
grates arranged in two or more distinct sets, each set being lower than
the one in front; these sets of grates are supported on plates, antifriction
rollers or rails secured to the sides of the furnace upon which they are
capable of sliding. Each set of bars projects beyond or overlaps the
next set of bars, the last set being placed over a stationary grate near
the bridge, thus giving a step-like formation to the grid or entire grate
of the furnace. The sets of bars have a forward and backward motion
imparted to them by tappets or eccentrics and rods independent from
each other; the first set of bars being the highest projects from the
front of the boiler under a hopper which is constantly kept supplied
with coal so as to prevent any air passing into the furnace except from
underneath the grate. When the fuel is ignited and the furnace is in
action the sliding bars are successively pushed forward from the highest
The intermittent
set to the lowest, after which they are withdrawn.
advance and return motion given to the bars causes them constantly to
carry and push forward the coal from the hopper towards the "bridge"
during its passage; whilst being thus propelled over the entire grate a
thorough consumption of coal and combustion of gas is effected, as the

page_text: fire commences gradually near the hopper and increases in brilliancy
and heat as it extends towards the bridge, thus causing the gases
evolved from the green fuel at the front of the grate to be entirely
consumed before they pass over the bridge into the flue.
And in order that my Invention may be fully understood and
readily carried into operation, I will proceed to describe the accom-
panying Sheet of Drawings, reference being had to the figures and
letters marked thereon.
'
Figure, 1 is an end elevation of an ordinary circular boiler with a single
flue to which my improved furnace is applied; Figure 2 is a side view of
the furnace and part of the boiler; Figure 3 is a section through the front
of the improved furnace; Figure 4 is a longitudinal section of the furnace
and part of the boiler; and Figure 5 is a plan of the improved furnace.
a is the outer shell of the boiler; b, the flue; c, the bridge; and
d, a water chamber forming part of the bridge, all of which are
made in the ordinary manner; and I wish to observe here that my
improved furnaces may be applied for generating steam in boilers
of various other descriptious and for other purposes. To the interior
of the flue are fixed the side plates e, e, the front ends of which
project beyond the end of the boiler, and are supported by the pillars
e', e; these side plates support the arch of fire-brick f which is
surrounded by a cast-iron casing to protect the bricks. To the casing
of the arch is fixed the hopper g, and between the arch and the hopper
is placed the sliding door h, the position of which can be varied to suit
the depth of fuel on the grate by means of pinions fixed on the shaft i
gearing into racks on the door or in any other convenient manner.
When the door is in the desired position it is held by the catch i' and
ratchet wheel, as shewn best in Figure 2. The front grate or set of fire.
bars is composed of three parts connected together, namely the dead
plate j, which in traversing to and fro remains at all times under the
delivering part of the hopper, the short set of fire-bars j', and the larger
set of fire-bars; the sides of this front grate are secured to the frame
which is hinged to the set of bars, the edges of which slide in grooves
in the side plates e; the four ends of the frame 3 pass through the
plate connecting the side plates e. The inner ends of the fire-bars 2
rest upon or are in close proximity to the middle grate k; the edges of
this grate also work in grooves in the side beams e, and the inner ends
of these fire-bars slide upon or close to the last grate which is also

page_text: guided in grooves in the side beams e. The ends of the bars traverse
over the short stationary grate m, beyond which is the water pocket n
which is in communication with the boiler. The object of this water
pocket is to prevent the burning away of the supports of the grate m
and the space under the water pocket n is closed by the door s. The
bridge c is placed at a certain distance from the water pocket n, to
allow space for the accumulation of clinkers and cinders. As the
hopper g is kept constantly supplied with coal it is evident that all the
air required for combustion must penetrate between and from under-
neath the grate bars. The grates j, k, and are traversed slowly to and
fro in the following manner:-Between the side plates are the cross
shafts o and p, which revolve in contrary directions being connected by
spur wheels, as shewn by the arrows in Figure 4; upon each of these shafts
are three pairs of cams marked o¹, 02, 03, and p, p2, 23, which act on
the studs projecting from the side rails of the frame 13 and rods
and connected to the grates j, k, and l. The shaft p has a worm
wheel p keyed to it which is driven by the worm q on the diagonal
shaft q, and this shaft is turned round by the bevel wheel driven
by the wheel fixed to the boss of the speed pulleys 7 loose on the
shaft r, but connected to it when required by the clutch box 3 in the
ordinary manner; the end of the shaft r is square to receive a winch
handle which may be turned round by hand to move the grates when
the steam power is not applied.
The Drawing represents the three grates in the positions they
occupy when drawn back, and the mode of operation is as follows:-
As the shaft p revolves the cams p¹ acting against studs projecting
from the side rails of the frame gradually push forward the
upper grate, consisting of the parts j, j¹, and j, as above described;
this motion causes the ends of the grate bars j to push forward the
coals on the middle set of grate bars k, and as the coals in the hopper g
are resting upon the dead plate j the advance of this plate carries
forward a portion of the fresh coal from the hopper; when the cams pl
have passed beyond the studs projecting from the side rails of the
frame the upper grate remains stationary until brought back by the
cams o, as will be described hereafter. Immediately after the upper
grate has completed its advance the cams p² have arrived in position
for acting on the studs projecting from the rods k¹, and as the shaft P

page_text: rotates the second grate k is gradually advanced thereby pushing
forward the coals and cinders on the third grate 1, which is then in
its turn caused to advance by the cams o³ acting on the studs projecting
from the rods ', thereby pushing forward the cinders and clinkers over
the stationary grate m and water pocket n, a portion of which drop
into the flue and are removed when required by the attendant, who
by drawing forward the rod a' raises the doors to admit a rake or other
instrument under the water pocket n. Soon after the lowest grate
has been made to advance it is again drawn back by the cams p' acting
on studs in the rods ; this retrogression of the grate allows a portion
of the coal or cinders from the grate k to drop on the grate 1.
The middle grate k is then drawn back by the cams o² acting ou the
studs of the rods k¹, thereby allowing a portion of the coal from the
grate to drop pn the grate ; and lastly the grate 3 is drawn back
by the cams o¹ acting on the studs of the side rails of the frame 3,
thus completing the operation and leaving all the grates in the positions
shewn in the Drawing. The effect of the fire-brick arch f is similar
to that of a reverberatory furnace, and ignites the fresh coal as it is
brought forward from the hopper by the advance of the dead plate j.
By means of these improvements it will be seen that so long as the
hopper is kept supplied with coals, the coals are regularly carried
forward on to the grates, and the coals so carried forward are gradually
consumed, while the inflammable gases evolved near the hopper pass over
the incandescent coals and are consequently consumed before they arrive
at the bridge, thereby consuming the coals in the most advantageous
manner and effectually preventing the production of smoke.
depth of the coal on the grates and the speed of the traversing motion
of the movable grates must be varied according to the peculiar quality
of the coals and to the size of boiler or the quantity of steam to be
generated. The order of succession in which the grates are moved and
the number of the grates may also be varied.
The
Having thus stated the nature of my Invention, and described the
manner of performing the same, I wish it to be understood that I
do not claim moving grates to and fro horizontally, being aware that
attempts have been made to construct furnaces with such movable
grates; but what I do claim is, the improved combination of two or
more movable grates and the machinery for working the same in
succession or otherwise, as shewn and described.

page_text: I also claim the movable grates in combination with the hopper g,
the fire-brick arch f, the stationary grates m, and the water pocket n,
as shewn and described.
In witness whereof, I, the said Thomas Wrigley have hereto set
my hand and seal, this Eighteenth day of February, One
thousand eight hundred and sixty-nine.
THOS. WRIGLEY. (1.s.)