Year: 1888

page_text: Date of Application, 25th July, 1888
Complete Specification Left, 25th Apr., 1889
Complete Specification Accepted, 1st June, 1889
We, WILLIAM JOHN GRAHAM and DAVID GRAHAM both of 116 Great Clowes Street,
Lower Broughton, Manchester in the County of Lancaster, Engineers, do hereby
declare the nature of our Invention to be as follows:-
Our said Invention relates to the furnaces of steam generators and chiefly to a
novel disposition of the grate or furnace bars whereby we obtain an increase of the
flue surface subjected to heat and are enabled to decrease the emission of smoke.
According to our Invention the bars comprising the grate are supported on curved
bearers extending across the flue, and we also cause the bars to slope downwards from
the front towards the back. The bearers are curved so as to raise the central bars
higher than those at the sides and as the extremities of the curve spring from the sides
of the flue at points considerably lower than from where a straight grate would extend,
we gain a considerable addition to the area of flue subjected to the heating effects
of the products of combustion. This area increases to a still greater extent as the bars
slope backward and downward towards the bridge or towards the substitute for the
bridge. To provide for the narrowing of the grate surface as it slopes towards the
bridge we taper the bars from front to back, and arrange them preferably in two or
any greater number of lengths, sometimes decreasing the number of bars in each
successive length. The whole grate surface thus presents a rounded or convex
One effect of such an arrange-
tapering surface upon which the fuel is stoked.
ment is that the air spaces between the bars are widest at the front where most
air is needed and narrowest at the back where less is required. As has been
already said our improved arrangement of furnace grate may be used in conjunction
with the ordinary bridge but we prefer a special grate back of fire brick having
a number of ports through which the products of combustion pass from the furnace
grate. This grate back soon becomes highly heated and communicates additional
heat to the smoke and heated gases passing through the ports, thereby causing the
said smoke and gases to burst into flame. We thus prevent or considerably reduce

page_text: the emission of smoke. We have found that by means of our invention an equal
pressure of steam can be generated with a considerably less expenditure of fuel and
we trace this economy of fuel mainly to the larger area of flue exposed to heat and
partly to the increased combustion of the smoke and gases.
Dated this 4th day of Into 1000
DUTTON & FULTON,
1, St. James Square, Manchester,
Agents.
COMPLETE SPECIFICATION.
Improvements in Boiler Furnaces.
We WILLIAM JOHN GRAHAM and DAVID GRAHAM both of 116 Great Clowes Street,
Lower Broughton Manchester in the County of Lancaster Engineers 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 and
accompanying drawings:-
Our said Invention relates to the furnaces of steam generators and chiefly to a
novel disposition of the grate or furnace bars whereby we obtain an increase of the
flue surface subjected to heat and are enabled to decrease the emission of smoke.
According to our Invention the bars composing the grate are supported on curved
bearers extending across the flue, and we also cause the bars to slope downwards
from the front towards the back. The bearers are curved so as to raise the central
bars higher than those at the sides and as the extremities of the curve spring from
the sides of the flue at points considerably lower than from where a straight grate
would extend, we gain a considerable addition to the area of flue subjected to the
heating effects of the products of combustion. This area increases to a still greater
extent as the bars slope backward and downward towards the bridge or towards the
substitute for the bridge. As has been already said our improved arrangement of
furnace grate may be used in conjunction with the ordinary bridge but we prefer
a special grate back of fire brick through which the products of combustion pass
from the furnace grate. This grate back soon becomes highly heated and com-
municates additional heat to the smoke and heated gases passing through the ports
thereby causing the said smoke and gases to burst into flame.
For the purpose of rendering our invention more clear we will now proceed to
describe the same more fully with reference to the accompanying sheet of drawings.
In the said drawings Fig. 1 is a longitudinal vertical section of a single flued boiler
having our invention applied.

page_text: Fig. 2 is a longitudinal horizontal section of the boiler showing the improved grate
in plan.
Fig. 3 is a cross section of Fig. 1.
"
In the
Fig. 4 is an enlarged view of one of the curved bearers upon which the bars rest.
As will be most clearly seen from Figs. 1 and 3 the grate bars a are carried upon
curved bearers which are formed and arranged in any suitable manner.
drawing the back curved bearer is formed in one with the plate 6' while in front
the bearer may form a part of the door frame 6. To assist in supporting the
central bearers rods c extend from front to back of the grate and the central bearers b
are formed with slots to drop over and rest upon the rods as most clearly shown
in Fig. 4. When the grate bars a are placed in the usual manner upon these
curved bearers the grate surface assumes a hog-backed" shape rising in the centre
and sloping down to either side. The points from which this curved grate surface
springs from the flue C are lower than the level of a straight grate surface thereby
subjecting a greater area of the boiler flue C to the action of the heat while at the
same time the area of grate surface is considerably increased. I will be observed on
reference to Fig. 1 that not only is the grate surface curved as described but that
also the bars slope downward from front to back thus making the grate surface
slightly narrower at the back than at the front, the whole grate tapering slightly
as indicated in Fig. 2. The bars therefore lie a little closer at the back than at
the front and as a consequence the air spaces between the bars at the back are
less than the similar air spaces at the front. This is an intentional result of the
arrangement, as more air is required at the front to burn the green fuel and less air
at the back where the fuel has become incandescent. The arrangement of bars
described and shown may be used with the ordinary bridge but we prefer to use it in
combination with the arrangement shown in the drawings. We carry the grate
back d which is of fire brick higher than the ordinary bridge and leave a space at
the top as shown for the passage of the heated products of combustion. This
space or part follows the curve of the flue as clearly shown at Fig. 3 and all of the
smoke, flame and heated gases passing over the back d are brought into close
contact with this portion of the flue thereby extracting the full beat. Behind this
backing d and separated from it by a space A of suitable extent I place another
division e of brickwork and at a distance indicated by the space f I place a third
division 9. Finally I place the division h at the back of all and at a distance from
the division g represented by the space B. All of these divisions are of fire brickwork
so as not to suffer from the extreme heat to which they are subjected. As has
been already said a space is left at the top of the grate back d for the passage
of the smoke and products of combustion from the furnace grate. A similar space
but of less depth is left at the top of this divisione but the division g touches the top
of the flue. At the bottom of the divisions e and g we leave spaces i and j and at
the top of the division h is left a space k for the final exit of the smoke from the baffle
arrangement. To split the up and down draught through the spaces A and B we place
dividing projections I and m therein which extend respectively from the divisions e
and h. The shape of the projections is clearly indicated by dotted lines in Fig. 3
of the drawings and in plan in Fig. 2. As indicated in Fig. 3 these projections are
wedge shaped or inclined or tapered but they might be straight or zig-zag or of other
forms. The course of the smoke, flame and heated products of combustion is clearly
shown by the arrows in Figs. 1 and 2. As these indications show, the smoke, flame
and gases on rising from the grate flow through the space at the top of the back d.
Parts of the products continue their way along the crown of the flue and pass over
the top of the next division e and so down between the divisions e and g, but the
main portion decends through the split space A and passes through the spaces i
and beneath the divisions e and 9. The divided currents are united beneath the
division g and rising together through the divided space B escape finally through the
space over the division h. By exposure to the flame the various brickwork
divisions become red hot and any smoke and heated gases which may have come
unconsumed over the first division d are ignited by impinging upon these incandescent

page_text: It
surfaces the result being that the whole of the fuel is utilised and the emission of
smoke almost entirely prevented when the boiler has got properly to work. We
do not bind ourselves to the proportions and distances apart of these brickwork
baffling and heating arrangements as it is evident they may be greatly varied.
In addition to the economical smoke consuming and heat imparting effects obtained
from these brick work divisions, we obtain this advantage that the dust and fouling
usually deposited in flues to the detriment of their heating qualities is arrested at the
front part of the flue by the baffling received by the draft from the various divisions.
The dust is thrown down before the draft passes the last division and can be easily.
removed without stopping the working of the boiler by the following means.
will be seen on reference to Fig. 1 that there is a space n beneath the first division d.
This is not of course intended as a passage for the draft but serves to facilitate
the aforesaid cleaning. Under ordinary circumstances this passage is closed by a
damper valve o which is hinged in the manner of a throttle valve and balanced on its
pivot so that it can be raised from its inclined closing position as shown in the
drawing, to a horizontal position by means of a hook wielded from the front of the
boiler. When the valve o has been thus opened, a rake can be introduced up to
the back division and all of the dust thrown down by the draft can be raked
forward along the bottom of the flue and so removed. When this has been done the
valve-o is again closed so as to stop the passage n.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :
1. In steam generator furnaces the employment of a grate surface of a curved or
hog-backed section so as to obtain an increased amount of grate surface and subject a
larger proportion of the flue to the action of the heat substantially as described and
shown.
2. In steam generator furnaces a furnace grate curved or hog-backed in the
direction of its breadth and sloping downward from front to back in the direction of
its length and supported upon curved bearers substantially as herein before described
and shown.
3. In steam generator furnaces the hereinbefore described curved or hog-backed
furnace grate in combination with the fire brick baffling and smoke consuming arrange-
ments substantially as described and shown.
Dated this 24th day of Au 1880
DUTTON & FULTON,
1, St. James Square, Manchester,
Agents.