IMPROVEMENTS IN THE CONSTRUCTION OF FURNACES, AND IN APPARATUS FOR IMPROVING THE DRAUGHT AND PREVENTING THE FORMATION OF SMOKE
Year: 1882

page_text: LETTERS PATENT to James Hodgkinson of Bolton in the County of Lancaster
Engineer for an invention of "IMPROVEMENTS IN THE CONSTRUCTION OF
FURNACES, AND IN APPARATUS FOR IMPROVING THE DRAUGHT AND PREVENTING
THE FORMATION OF SMOKE"
"
PROVISIONAL SPECIFICATION left by the said James Hodgkinson at the
Office of the Commissioners of Patents on the 27th March 1882.
JAMES HODGKINSON of Bolton in the County of Lancaster, Engineer.
IMPROVEMENTS IN THE CONSTRUCTION OF FURNACES, AND IN APPARATUS FOR
IMPROVING THE DRAUGHT AND PREVENTING THE FORMATION OF SMOKE."
The first part of this invention is designed principally to be applied to the
construction of the furnaces of Steam Boilers, when fed automatically by what is
known as "Mechanical Stokers," but it may also be adapted with advantage to
other furnaces.
The invention relates to the construction of the furnace bars and their
appliances with a view to the more economical and perfect combustion of the fuel
employed.
In an arrangement of self-cleaning fire-bars, I place them transversely in the
flue on endless chains or bands, the later being supported on pullies, carried on
centres working in fixings provided for them at the front of the, boiler and inside
the flue. The bars are fastened to the endless chains or bands with bolts, pins or
other equivalents, being placed at suitable distances leaving the requisite air spaces
between the bars. The bars and endless chains or bands are worked by a shaft,
provided with cams, eccentrics or wheels placed outside the furnace front, working
them from front to back.
In feeding the furnace with fuel, I feed on only a portion of the fire-bars, when
it is carried towards the back end by the revolving motion of the bars and endless
chains or bands. As the bars revolve round the back pullies, the ashes and clinker
are deposited into a combustion chamber, when the bars continue to revolve

page_text: underneath towards the front end being free from ashes and clinker, and round the
pullies at the front end, when they advance under the dead plate into the furnace
to be re-charged with fresh fuel and so on continuously.
If necessary I can feed the bars at the back end, the bars travelling from back to.
front with the fire, thus depositing the ashes and clinker outside the flue at the
front of the boiler.
Iu applying these bars to a circular flue, I place longitudinal stationary side-bars
along the sides of the flues, provided with air spaces, sufficiently wide to allow of
the revolving bars being shortened so as to allow them to travel underneath in the
contracted part of the flue.
The second part of this invention is designed for improving the draught so as to
assist the combustion of the fuel, and consume smoke.
I place near the fire-door a steam pipe having one, two or more air nozzles
communicating with the atmosphere, in the centre I place or fix a steam jet
having a small outlet, projecting into the centre chamber of the air nozzles, the
opposite end of the steam pipe projecting through holes or openings prepared for
them in the fire-fronts. The steam jet is supplied with steam from the boiler
through ordinary pipes, the amount being regulated by a steam tap.
By these means the gases inside the flue are supplied with a fresh supply of air
through the air nozzles, when the oxygen it contains immediately ignites with them
producing a pure flame, thereby consuming a large amount of smoke, raising the
temperature of the fire and gases in the flue, consequently the draught is increased,
also the economic value of the fuel.
The novelty of this invention is its simplicity, requiring very little attention after
being set to work, doing its work effectively, and in the manner in which it
thoroughly cleans the bars from ashes and clinker, at the same time when out of
the fire, having time to cool, which must lengthen the life of the bars...
Another feature is that the bars can be easily changed without stopping the boiler
or taking the fire out, should they become damaged or otherwise.
By the application of my improved steam jets and air-nozzles the efficiency of
the furnace is considerably improved, as well as smoke consumed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Hodgkinson in the Great Seal Patent Office on the
25th September 1882.
"
JAMES HODGKINSON, of Bolton, in the County of Lancaster, Engineer,
* IMPROVEMENTS IN THE CONSTRUCTION OF FURNACES, AND IN APPARATUS FOR
IMPROVING THE DRAUGHT AND PREVENTING THE FORMATION OF SMOKE,"
The first part of my invention is designed principally to be applied to the
construction of the furnaces of steam boilers, when fed automatically by what is
known as "Mechanical Stokers," but it may also be adapted with advantage to
other furnaces.
The invention relates to the construction of the furnace bars and their appliances
with a view to the more economical and perfect combustion of the fuel employed.
In an arrangement of self-cleaning fire bars, I place them transversely in the flue
on endless chains, the latter being supported on pullies, carried on centres working
in fixings provided for them at the front of the boiler and inside the flue. The
bars are fastened to the endless chains with bolts, pins or other equivalents, being
placed at suitable distances leaving the requisite air spaces between the bars. The
bars and endless chains are worked by a shaft provided with cams, eccentrics or
wheels, placed outside the furnace front, working them from front to back.
In feeding the furnace with fuel, I feed on only a portion of the fire bars, when
it is carried towards the back end by the revolving motion of the bars and endless
chains. As the bars revolve round the back pullies, the ashes and clinker are
deposited into a combustion chamber, when the bars continue to revolve underneath
towards the front end, being free from ashes and clinker, and round the pullies at
the front end, when they advance under the dead plate into the furnace to be
re-charged with fresh fuel and so on continuously.
If necessary I can feed the bars at the back end, the bars travelling from back to
front with the fire, thus depositing the ashes and clinker outside the flue at the
front of the boiler.
In applying these bars, I place longitudinal stationary side-bars along the sides
of the flues, provided with air spaces, sufficiently wide to allow of the revolving
bars being shortened so as to allow them to travel underneath in the contracted
part of a circular flue.
The Second part of my invention is designed for improving the draught so as to
assist the combustion of the fuel and consume smoke.
I place near the fire-door a steam pipe having one, two or more air nozzles
communicating with the atmosphere, in the centre I place or fix a steam jet having
a small outlet, projecting into the centre chamber of the air nozzles, the opposite
end of the steam pipe projecting through holes or openings prepared for them in
the fire fronts. The steam jet is supplied with steam from the boiler through
ordinary pipes, the amount being regulated by a steam tap.
By these means the gases inside the flue are supplied with a fresh supply of air
through the air nozzles, when the oxygen it contains immediately ignites with
them, producing a pure flame, thereby consuming a large amount of smoke, raising
the temperature of the fire and gases in the flue, consequently the draught is
increased, also the economic value of the fuel:
In order that this my said invention may be more readily seen and fully
understood so as to be carried into operation, I have hereunto annexed drawings,
illustrative of my improvements, reference being made to the figures and letters'
marked thereon..

page_text: Fig. 1 is a longitudinal vertical section of my improved fire-bars, as applied to
and within the front end of an ordinary internally fired steam boiler, when fed
automatically by what is known as "Mechanical Stokers," Fig. 2 is a plan of the
said fire-bars, one flue showing them complete, the other part showing the front
and back shafts or bearers and chains on one side, with the fire-bars removed.
Fig. 3 is a front elevation showing how they are applied to the front of a Steam
Boiler when used in connection with "Mechanical Stokers," the latter representing
my improved Stoker for which Letters Patent were granted the 25th day of
July 1879 and numbered 3042. These improved fire-bars will be more readily
seen and understood by referring to Figs 10 and 11, which are sectional side
elevations through lines A1 A2 A3 and A* respectively, and Fig. 12 is a transverse
section through lines A³ and Aº
In my improved arrangement of self-cleaning fire-bars, all the moveable or
travelling bars A are placed transversely across the furnace or flue, and are made
shorter than the width of the flue to allow them to travel underneath in the
contracted part, as shown in Fig. 12, being provided on the underside with the
snugs or lugs B, as in Figs 12, 14 and 15, by which they are coupled to the endless
chains C, by which they are moved. To relieve the chains C from the weight of
the bars and fire on then, the ends of the moveable bars A slide on the projections
or slides D placed on the inside of the side-bars E, as shown in Figs 12, 22,
and 23.
In another modification I place the slide D on the side-bar E considerably lower
down, and much broader, so as to allow the endless chains C to slide on, thus
relieving both the chains and the bars A of their weight and that of the fire on
them, as shown in Fig. 12 A, or as shown in Fig. 12 B in which case I make the
channel W for the chain C and the end of the transverse bars A to slide in, in both
cases the slide D' is provided to allow the bars to slide on whilst making the
return journey underneath.
The endless chains C are supported and worked by the chain wheels F and
pullies G carried or working on the centres or shafts H which are supported in
the bosses or journals I provided in the side-bars E. The endless chains C are
made with the inside concaved to the radius of the pullies round which they
revolve at the extreine ends, the outer side being made convexed, with the increased
radius in proportion to the width of the links, as shown more fully on an enlarged
scale in Figs 36 and 37. The links are provided with the round holes c, through
which passes the bolts or pins d, over which is passed the ferrules e, for determining
the permanent distance between the links C, over which is placed the lugs or
snugs B on the underside of the bars A. The moveable bars A are set transversely
across the flue, side by side, being provided on the outsides, either at the ends or
in the middle, or at convenient spaces as shown, with the distance pieces f, thus
forming the requisite air spaces g, between the bars. The side-bars E, are placed
longitudinally along the sides of the flues, provided with the air spaces h to admit
of the necessary quantity of air to supply the fuel falling on them, the front ends
of these bars are inade with a jaw or slide-bar, provided with the sliding block J,
through which the front working shaft H passes, the block J being adjustable to
enable the links or chains C to be tightened or otherwise, should they require it,
by the adjusting screws. The side bars E are fastened to the boiler or to the
furnace front or "mechanical stoker" by the brackets K, being secured by bolts, or
other equivalents, the back ends being carried on the combustion chamber plate or
fixing L, the latter being firmly fixed to the flue of the boiler.
The bars being put together as described and shown in Figs 1, 2, 3, 10, 11
and 12, they are worked with the chain wheels F, fixed on the shaft H for
traversing the forward and return set of bars A, at a slow speed as shown in Figs 3
and 4, by the ratchet-wheel m, on the shaft H, actuated by the loose oscillating
levers and catch o, taking into the teeth of the ratchet wheel m, on the up stroke
of the inner end of the levers n, raised by the outer slotted ends being lowered by
the action of the reciprocating connecting rod p, attached to and actuated at the

page_text: upper end by the eccentric r, placed on the crusher shaft s, of-the stoker, or it may
be worked from an overhead slow-motion shaft for the purpose, not shown in the
drawings, the same being a well-known and common mechanical motion. If
desired they may be worked by placing the worm wheel t, on the shaft H, driven
by the worm (shown in dotted lines) worked from the driving gear of the
mechanical stoker or any other convenient mode of driving. The bars are con-
tinued a sufficient distance out in front of each furnace flue and furnace door, to
enable the shaft H to be worked.
Above the bars immediately inside the furnace door is fixed the short dead
plate M (which is not required when a shoot is employed for supplying fuel instead
of by either "Mechanical Stoking" or hand firing) under which the bars A and
chains C travel, towards the back end as indicated by the arrow, the front part
being supplied with fuel from the hopper or mechanical stoker, which only feeds
on a portion of the grate surface, say from one third to one half or more when it is
carried with the bars A towards the back end by the revolving motion of the
shafts H, which work the chains C, and drag the bars A in at a slow but regular
speed when worked by worm and wheel or by an intermittent motion when
worked by the ratchet wheel m, and catch o, as shown in Fig. 4, proportionate to
the rate of combustion, actuated by the transverse shaft H, working in the
adjustable blocks or bearings J, in the outer end of the side-bars E; the endless
chains C working round the pullies G, where the upper range of furnace bars A
are moved round and down on the bottom slides D', bringing the line of bars A
back in an inverted position to their front raising and moving shaft H. and chain
wheels F, so as to be raised by them and again led and dragged forward as before
described constantly emptying all the partially burned fuel in an incandescent
state at L, into an ordinary combustion chamber, fitted with the hinged door L¹
separating it from the ash-pit N, and for regulating the admission of air to the
coin bustion chamber O, when the fuel is burned therein between the end of the
furnace bars A and the bridge P.
"
If desired the stationary back shafts H can be made to revolve; in which case
the ends are made round, working in the journals or bosses I on the side bars E,
also instead of the pullies G can be used the chain wheels F, similar to those fixed
on the front shaft H, in such cases the chain wheels are fastened to the shafts H
by the key t, or other equivalents as shown in Fig. 13.
Fig. 34 shows another method I use in fixing the back shafts H into the side-
bars E, which allows of its being taken out without disturbing the side-bars, which
I accomplish by making the ends of the back shafts H square which fits into the
preparation I' and over the entrance of which is fixed the cap or cover I2 the same
being secured by the bolts I³.
Fig. 35 is a sectional plan of the same through line C' D¹.
There being several ways in which the back shafts H can be fixed, I find that a
great advantage is obtained and time and labor saved in fixing by making the
vertical slots I in the top side of the side bars E, the bottom being lengthened
towards the front end sufficiently to enable the square ends of the shafts H to lie.
flush or nearly so, the front part being solid and which is against the pull of the
bars.
This arrangement also enables the bars when being put together to be put
in bodily, and lifted a little at the back end and dropped in, which dispenses with
both cap and bolts as shown in Fig. 34 A.
Fig. 35 A is a plan of Fig. 34 A.
Fig. 19 is a plan of the fire-bars A, shown in Figs 1, 2, 3, 10, 11 and 12 in
which case it will be seen that two bars are cast together, with the air spaces g,
left between them and the distance pieces f, placed in the middle and at the two
extremities.
Fig. 20 is an end view of the same bar, shewing the snugs or lugs B and the
ends which are provided with the small bearing pieces a³ for reducing the friction,
when travelling on the slides D on the stationary side-bars E.
Fig. 21 is a transverse section through the same bar on line A¹ B¹ in Fig. 19.

page_text: travelling bars, which consists of the centre rib or plate R, made "fish-belly" in
form, having along the upper edges, the projections or teeth 62 in a serrated form
on each side, the projection on one side being (by preference) opposite to the space
on the other, and the projections and spaces of the contiguous bars interlocking
with each other, having the distance pieces f cast to each end, so as to leave
between them the air spaces g, of a serrated or zigzag form, by which an increased
air space is also obtained without making the opening between the bars wider.
The spaces and projections can be made semi-circular as shown or straight and
tapered as in Fig 27. The snugs or lugs. B are for coupling the same to the
chains C, as shown in Figs 12, 14 and 15.
Fig. 17 is a plan of the fire-bars A shown in Fig. 10.
In another form of fire-bar I cast them three bars together as shown in Figs 24,
25 and 33, the air spaces and distance pieces being left similar to those described
in Fig. 19.
In another arrangement I make the mid-feathers R of the bars oblique, as shown
in sections Figs 31 and 32.
Figs. 17 A, 28 and 30 are end views of bars in Figs 17, 25 and 27 respectively.
Figs 18, 29 and 33, are sections through lines C D in Figs 16, 26 and 24
respectively.
Fig. 26 is an elevation of fire-bars A as shown in plan Fig. 27.
Another important feature and novelty in this invention is that of working or
traversing the fire-bars A the reverse way to that previously described, in which
case the combustion chamber O, in Fig. 1, is dispensed with, the bridge P being
built close to the end of the bars and on the plate S, which extends over them,
being supported and held in place by the stops or projections T, cast to the top
side of the side-bars E. In this arrangement the fuel being fed must be thrown
on the back part of the bars completely to the bridge P, which is effected by
increasing the speed and power of the "mechanical stoker," and as smoke cannot
be consumed after it has left the furnace, unless air is supplied to mix and ignite
with it, which is best admitted near to where the gas is generated, which I
accomplish by making the air space w, at the end of the bars A, by leaving
sufficient clearance between the top of the bars and the underside of plate S
which supports part of the bridge P, as shown in Fig. 5.
I find that when some kinds of fuel are being used, that owing to its extreme
gaseous nature, that it runs on the bars, causing them to burn quickly. To meet
such cases I make the top side of the bars A as shown in Figs 24 A and 25 A, on
which I place suitable coverings, such as cast or wrought iron, steel, asbestos or
other non-conducting substances, which is secured by the bolts or set screws or
keys, driven in from the ends, and as the coverings burn they can be replaced at
will when required, without destroying the bar,
The Second part of my invention relates to an improved method of improving
the draught so as to assist the combustion of the fuel, by supplying the furnace
with steam and air in sufficient quantities to divest the smoky products of
combustion of their carbonic acid gases, and supply air to ignite the hydro-carbons
and olefiant gases as they are released, and which I accomplish as follows:-
I place near the fire-door as in Figs 1 and 3 the steam pipe c², which is fitted
with the chamber d², being provided with the air nozzles e², communicating with
the atmosphere. The centre of the chamber d is provided with the small conical
steam jet f, the outlet from the latter being from 1/16th to 1/8th of an inch in
diameter, being secured by the nut g²; at the opposite side of the chamber is
fixed the pipe h², projecting through the holes, in the furnace fronts. The
pipe 2, is coupled to the boiler in any convenient position, the steam. valve m³
being for the purpose of supplying the steam jet f2, in the chamber d² with steam,
which when admitted forms a vacuum, when the atmospheric air rushes through
the nozzles e², which passes along and unites with the steam, which upon entering
the furnace unites with the rising products of combustion thereby increasing the

page_text: draught, so that a more perfect combustion is maintained, as well as the
temperature of the fire increased, with a given amount of fuel.
Fig. 6 is an enlarged view of the chamber d, when provided with one air
nozzle e², Fig. 7, when provided with two nozzles, Fig. 8 when with three, and
Fig. 9 when with four air nozzles. I can provide it with more air nozzles, by
simply making the chamber d² of a larger diameter, making the air nozzles e² of
any convenient size to suit the various requirements.
Having thus stated the nature of my invention and described the mode of
performing the same, I would have it understood that I do not confine myself to
the precise details or configuration of the parts I have shown and described, as the
same may be varied or modified without departing from the principle of my
invention, I also wish it to be clearly understood that I am fully aware that
steam and air have previously been introduced for the purposes described, but
what I claim and desire to be secured to me by Letters Patent is :-
First. The general construction or arrangement and combination of parts,
forming my improved furnaces so arranged and moved that they are made to act
as self-cleaning surfaces, with inward and return moving sets of transverse grato
bars in steam boiler and other furnaces, substantially as described and shown in
the accompanying drawings, or any mere modification thereof.
Second. The construction, arrangement and use of inward and return moving
transverse fire-bars, actuated and moved by endless chains working round chain
wheels and pullies, carried on shafts placed at each end of the furnace, substantially
as described and as shewn on the drawings, or any mere modification thereof.
Third. The construction and use of stationary side bars or their equivalents in
connection with mechanically moving transverse bars with the slides D for
carrying and guiding the upper range of bars or bars and chains and the slide D'
for carrying and guiding the lower range of bars, with the arrangements for
carrying, adjusting and supporting the ends of the shafts H, round which the bars
and chains move, with the means employed for admitting air to the sides of the
furnace, substantially as described and as shown on the drawings, or any mere
modification thereof.
Fourth. The construction and use of endless chains for the purpose of moving
transverse bars, substantially as described and as shown on the drawings in
Figs. 36 and 37.
Fifth. The general construction or arrangement and combination of parts forming
my improved furnaces so arranged and moved that they are made to act as self-
cleaning surfaces, with the outward and return moving set of transverse grate-bars,
depositing the ashes and clinker outside the furnace front, when used in connection
with mechanical stoking in steam boiler and other furnaces, with the bridge
arrangements as shown in Fig. 5, substantially as described and shown on the
drawings.
Sixth. The combination and use of the chamber d, with the air nozzles e² and
the steam jet f*, in connection with the steam and inlet pipes c² and h³, the whole
forming apparatus for injecting steam and air into the furnaces in a horizontal
plane or otherwise above the burning fuel, for the purpose herein described, and
substantially as shown on the drawings.
In witness whereof I the said James Hodgkinson have hereunto set my hand
and seal this twenty-second day of September in the year of our Lord one
thousand eight hundred and eighty two.