Improvements in Smoke-consuming Furnaces and Mechanical Stokers.
Year: 1896

page_text: Date of Application, 26th Sept., 1896
PROVISIONAL SPECIFICATION.
Improvements in Smoke-consuming Furnaces and Mechanical
Stokers.
I, CHARLES GROLL, of Roubaix (Department du Nord), in the Republic. of
France, Engineer do hereby declare the nature of this invention to be as follows:-
The object of my invention is to effect the consumption of smoke by rendering
the combustion of fuel methodical, that is to say, 1st by causing the fresh fuel to
fall always upon flowing fuel; 2nd by increasing the travel of the gases produced
in the combustion chamber and by causing them to mingle there as much as
possible, 3rd by successively conducting these gases to portions of the fuel in the
farnace which are more and more heated.
My invention consists essentially of a rotatable grate in combination with a
feeding or firing device which distributes the fuel automatically with respect to the
radius of the grate; my said invention also relates to the constructional arrange-
ment of the furnace, the whole co-operating to produce perfect and methodical
combustion of the fuel and at the same time a perfect or all but perfect consump-
tion of the smoke.
The support for the grate consists of a toothed crown or circular frame which is
carried on rollers mounted in supports embedded in the brickwork of the ash-pit.
The rollers are capable of displacement in the direction of their axes so that
they may offer no resistance to the expansion or contraction of the toothed circular
frame, which later is made in two pieces in order to facilitate its mounting.
Arms radiating from a common hub have their outer extremities resting in
recesses provided in the said circular frame for their reception. Other arms
which bisect the intervals between the first named arms, are supported at their
inner ends by projections from the hub above referred to, and their outer ends
rest upon the supports of the circular frame. These two sets of arms serve to
support the fire bars which are of special form and of varying lengths in order to
cover the annular surface, and of varying sectional area according to the nature
of the fuel employed. The bars are arranged as closely as possible to a fixed crown
or second circular frame which is bedded in the brickwork of the furnace; as the
said bars and also the said circular metal frame or crown are made up of
sections, their expansion can take place without any damage being thereby
occasioned. The first named radial arms are provided with slots, and the inter-
mediate arms are built up each form two vertical bars joined at their extremities
and more or less separated one from the other. The spaces between the said
arms serve for the reception of the heels of the fire-bars.
The toothed circular frame is centred upon a central column by means of its
hub, and gears with a pinion which receives a continuous or intermittent rotary
movement by means of any suitable actuating device. The said column is formed
with an elbow near its lower end and at the extremity of such elbow a double
elbow is provided which leads back in front of the ash pit the air drawn in at
the front through a chamber located above the grate; a jet of steam aids in the
suction of this air which is heated during its passage and which assists combustion.
The column forms a continuation of the chamber located above the ash pit the
vertical base of which chamber at the centre of the grate.
The air drawn in through the said chamber circulates therein and cools the
chamber sufficiently to prevent its being injured by the heat of the furnace. The

page_text: said chamber is in addition suitably protected throughout its whole extent by
refractory bricks of appropriate form; it is maintained firmly fixed between
the arches of the furnace one. end of it resting upon the central column and the
other end being embedded in the brickwork at the front of the boiler.
Within the said chamber is located a cast iron box which; forms the fuel-feeding
or firing apparatus proper; it is prolonged outwardly and connects with the fuel
distributor. The said feeding or firing apparatus is composed of a series of
inclined parallel partitions which terminate at different points upon a single arm
or radius of the grate. These partitions, which have a convex upper surface
in transverse section, receive the fuel from the distributor and as a reciprocating
movement is imparted to them, they cause the fuel to slide down and fall into
the furnace, at the same time effecting a proper distribution of the fuel with
respect to the grate. The chamber before mentioned surrounds the feeding or
firing apparatus; it is cast with a longitudinal heel or foot in which are provided
passages for the admission of air. The external air, admitted through these
passages becomes heated in traversing them and escapes on the inner surface of
the heel in the form of jets which prevent the furnace gases from entering the
feed or firing chamber. These jets of hot air which are normally ejected in the
direction of the left boiler, also serves to direct the gases driven off from the fresh
fuel in such a manner as to force them to pass right round the grate and thus
be completely consumed.
In the longitudinal walls of the foot of the box, enclosing the parallel feeding
partitions, two passages are likewise provided in which the air taken from outside
circulates, such passages causing the formation of jets which assist the action of the
beforementioned jets in preventing the gases from rising into the box of the firing
apparatus.
The fuel distributor placed outside the brickwork of the boiler comprises a
box, into which the fuel is conveyed either by means of a hopper or by a feeding
screw, and a second box in which turns a perforated cylinder which is the dis
tributor proper. The fuel passes through the openings in the said cylinder and
falls into one of the compartments of the said second box and from thence upon
one of the partitions of the firing apparatus.
A metallic brush rests constantly against the surface of the distributing cylinder,
its pressure being regulated by springs which allow of its yielding when necessary.
With the foregoing arrangement the fuel is perfectly distributed amongst the
openings in the cylinder and each compartment of the second box receives only the
fuel coming from such feed openings as immediately correspond to it. It is thus
easy to predetermine the character of the supply of fresh fuel for each portion of
the grate.
The circulation of the gases is effected in the following manner:
The gases given off by the fresh fuel are impelled by the jets of hot air above
referred to towards the rear of the left-hand boiler. The furnace arch concentrates
the heat in that part where the fuel is ignited and where the temperature should
be sufficiently high to effect the combustion. The gases before passing into the
escape flues, go right round the grate and burn methodically, those gases which
are the most consumed being caused to come successively into contact with fuel
heated more and more highly: With this object the bridge is closed by othe
arches and a vertical wall so that the gases, after having passed under the furnace
arch, rise at the rear up to the arch at the bridge and are then deflected laterally
and passing along the lower portions of the boilers at the rear, descend,in order
to pass under another arch and proceed towards, the front until they again cone
in contact with the grate and complete their combustion. They then rise in front
of the second furnace arch, heat the front and upper portions of the boilers and
escape into the flues which conduct them to the chimney.
In order that the gases from the fresh fuel, may constantly complete the same
cycle, it is obviously necessary that, in proportion as it is consumed, the fuel.shoul
be displaced. This I effect in a very simple manner by distributing the fuel along

page_text: one arm or radius of the grate and by causing the grate to rotate around its centre.
This continuous rotation of the grate which is supplied with fuel in an automatic
and radial manner, effects a complete and methodical consumption of the smoke,
because the gases which are more and more burnt come in contact with fuel
heated to a greater and greater degree, the whole proceeding in the same way:
In the above description I have assumed the improvements to be applied to
a double boiler having two furnaces. The said improvements are however
applicable to the greater number of existing steam generator furnaces.
Dated this 26th day of September 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant,
Improvements in Smoke-consuming Furnaces and Mechanical
Stokers.
I, CHARLES GROLL, of Roubaix (Department du Nord), in the Republic of
France, 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:-
In all furnaces having round or rectangular grates the gases liberated are
carried behind the fire-bridge before being consumed, and, as a consequence, the
heat obtained from the fuel has hitherto been far less than that which it is
theoretically possible to obtain.
A very large number of appliances have been tried or proposed for consuming
the smoke of furnaces, the escape of which is as objectionable from an economic
as from an hygienic point of view; but, generally speaking, the result is still
dependent upon the stoking, because in all such modifications or additions as
bave been adopted, the form of grate hitherto employed has been retained, some of
such grates being wholly immovable, others being movable as regards their
constituent parts, but not capable of displacement as a whole.
The object of my invention is to effect consumption of the smoke by rendering
the combustion systematic, that is to say: firstly, by causing the fresh fuel to fall
always upon live or glowing fuel; secondly, by increasing the distance through
which the gases produced in the combustion chamber pass, and by causing them
to mingle there as much as possible; thirdly, by successively conducting these
gases over more and more heated portions of the fuel.
My invention consists essentially of a rotating grate in combination with a
charging or feeding device which automatically distributes the fuel along the
radii of the grate; my said invention also relates to the constructional arrangement
of the furnace, the whole co-operating to effect a perfect and systematic combustion
of the fuel, combined with a complete or almost complete consumption of the
smoke.
In the accompanying drawings the distinctive characteristics of my invention
are clearly indicated.
Figure 1 represents a vertical cross-section of the furnace of a steam generator,
on the broken line 1-2-3-4 in Figure 2.
Figure 2 is a longitudinal section on the line 5-6 in Figure 1, that is to say
en the longitudinal axis of the furnace.
Figure 3 is a plan of a rotatable grate, most of the bars being removed, and
the section of the furnace being on the line 7-8 in Figure 1.

page_text: The same Figures 15 and 16 likewise shew the foot of the radial charging
chamber replaced by an arch i of hollow refractory bricks, continued by a metal
pipe into which air is forced from the outside and issues in jets m', preventing
the furnace gases from rising into the charging chamber h, and causing them to
pass completely round the grate.
In Figures 17 and 18 is shewn a further arrangement for the automatic charging
apparatus. The tubes u for conducting the fuel, in which turn the screws u²,
are open at their extremities in a straight section, but they are of different lengths.
In order to distribute the fuel with this arrangement along a radius of the grate,
the system, comprising the hopper, the screws and their tubes, travels in the
direction of the radius with an appropriate stroke and speed.
The circulation of the furnace gases which ensures their complete combustion,
takes place as follows:
The gases given off by the fresh fuel are driven towards the rear of the left:
band boiler by the jets of air coming from the box h and from the blower arranged
under the radial box g. The arch A concentrates the heat at the place where
the combustion of the mixture of air and gas begins. This combustion continues
at a constantly increasing temperature, the said mixture having to pass completely
round the grate before passing into the flues. With this object the fire-bridge is
closed, and the arches B B and also the vertical wall D), deflect the gases, after
they have passed under the arch A, and cause them to proceed in contact with the
lower portions of the boilers XX and to descend so as to pass under the arch A¹
in passing towards the front. At this point the combustion should be perfect
if the mixture of air and gas has been effected in the requisite proportion for the
fuel employed, such proportion being readily regulated by means of the blowers
which supply the air above the grate. The gases then ascend in front of the
arch A', heat the front and upper parts of the boilers and escape into the flues
which conduct them to the chimney.
In order that the gases from the fresh fuel may constantly effect the same cycle,
it is obviously necessary that, in proportion to its consumption, the fuel should
be displaced. This is effected by simply distributing the fuel along a radius of
the grate and by causing this grate to turn bodily around its centre f. This con-
tinuous rotation of the grate, fed in the automatic manner described which is both
radial and constant, should effect a consumption of the smoke both complete and
systematic, because the gases, more and more completely burned, successively come
into contact with fuel at an increasingly greater heat, such cycle of operations.
being continuous.
My rotating and automatically charged grate is capable of being applied to
most of the known forms of generator furnace.
The grate, instead of occupying practically the whole of the circle comprised
within its outer rolling circumference, may be reduced to a mere crown and a
detached central part as shewn in Figure 12. In this case two series of rollers
would be used, placed plumb with the external and internal circumferences of the
crown..
This arrangement of the grate with an open central portion of large diameter,
will in certain cases facilitate the transformation of ordinary generator furnaces
into smoke consuming furnaces according to my invention with rotating grate and
automatic fuel charging apparatus.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I declare that what
I claim is:.
.
1. A smoke-consuming furnace for steam generators or other industrial
apparatus, consisting of a grate to which a continuous or intermittent rotary motion.
is imparted, and of an automatic charging apparatus which distributes the fuel
along the radius of the grate in such a manner that the fresh fuel always falls

page_text: upon live or glowing fuel, and that the combustion gases are directed in the
direction of otation of the grate in order to pass from the front to the back, return
to the front so a to complete their combustion and again rise and traverse the
flues leading to the chimney, the whole for effecting the systematic utilisation
of the fuel and the complete consumption of the smoke.
2. In the smoke consuming furnace described in Claim 1, the rotating grato
formed by a toothed crown mounted upon a fixed column rising from the bottom
of the ash pit, such crown being provided with radial arms upon which the grate
bars are placed, this grate resting upon rollers suitably distributed, substantially
as described and shown in the accompanying drawings.
3. In the smoke consuming furnace described in Claim 1, an automatic fuel
charging apparatus comprising a hopper, a rotating cylinder in the periphery
of which cavities are formed, which with the assistance of a flexible acting brush
distributes the fuel into passages o' forming continuations of and leading on to
superposed partitions in a channel radially placed relatively to the grate,
substantially as described and shown in the accompanying drawings.
4. In a smoke consuming furnace as described in Claim 1, a conduit t in which
turns an archimedian or conveyor screw and which receives the fuel from a
hopper and conducts it upon the grate, allowing it to fall along the whole radius
of this grate through its elongated and obliquely formed opening, substantia
as described and shown in the accompanying drawings.
5. In a smoke consuming furnace as described in Claim 1, superposed conduits u
of different lengths in which turn archimedian or conveyor screws and which
receive the fuel from a hopper and conduct it on to the grate, allowing it to fall
treugh their upright openings all along a radius of the grate owing to the
reciprocating movement which is communicated to them simultane msly in the
direction of the radius of the grate, substantially as described and shown in the
accompanying drawings.
6 In a smoke consuming furnace as described in Claim 1, a radial chamber g
surounding the channel h, or the conduits t or u, of the charging apparatus, and
joining at the centre of the grate the hollow column f around which said grate
turns, in order that the fresh air which reaches this chamber from the front of
the furnace and which is taken along by the jets of steam directed into the chamber
from outside, may become heated in proceeding towards the central column and
leave this latter in order to supply the grate, substantially as described and shown
in the accompanying drawing.
7. In a smoke consuming furnace as described in Claim 1, a radial chamber
in which circulates the air proceeding under the grate and which is provided
with a foot i having small passages into which air is blown from the outside, such
air escaping in lateral jets m' which prevent the combustion gases from rising
into the conduits of the charging apparatus, forcing them to pass completely round
the grate in the direction of its rotation, substantially as described and shown
in the accompanying drawing.
8. In a smoke consuming furnace as described in Claim 1, the arrangement of
the rotating grate whereby this latter is reduced to a mere crown having a free
central portion and provided with two series of rollers placed plumb with the
external and internal circumferences of the crown respectively, substantially as
described and shown with reference to Figure 12 of the accompanying drawings.
Dated this Ninth day of June 1907
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.