Improvements in Mechanical Stokers and Furnaces.
Year: 1890

page_text: Date of Application, 6th Nov., 1890
Complete Specification Left, 6th Aug., 1891-Accepted. 6th Nov. 1891
PROVISIONAL SPECIFICATION.
Improvements in Mechanical Stokers and Furnaces.
WILLIAM FRASER Engineer 99 Anderton Road Sparkbrook Birmingham do
hereby declare the nature of this invention to be as follows:-
First;
The mechanical supply of fuel to any kind of furnace and automatically
discharge the clinker (or refuse) from the fuel at the same time.
Secondly To increase the heating surface in the immediate vicinity of the grate
where the fuel is consumed, for the purpose of generating steam at a greater
rapidity.
Thirdly To utilize the grate for superheating the air required for combustion
and also as a water heater, or for generating steam if so desired.
Fourthly To secure the complete consumption of smoke and, the perfect com-
bustion of fuel.
Fifthly To ensure the better circulation of the water in the bottom of the boiler
by having the fuel all round the tube top and bottom, all the length of the grate.
To obtain these results I completely dispense with all the old furnace fittings,
viz., the fire bars, bearers, deadplate, furnace door, bridge and etc. The new furnace
grate is circular in form, and about twelve inches or thereby less in diameter than
the boiler tube, leaving a space of about six inches for fuel all round the grate
i.e. (the space be ween the outside diameter of the grate and the inside diameter of
the tube is) abc t 6". The grate can be made any length but, about four to five
feet long would answer the requirements best.
The outside of the grate is so formed that when it revolves the fuel is slowly
moved forwar along the boiler tube until it is consumed, the clinker then falling
over the end of the revolving grate and finally deposited in the bottom of the tube
at a distance of about 6 or 7 feet from the boiler front. The inside of the grate is
so formed that the clinker is automatically discharged by the revolving of same,
.e. the revolving grate feeds the fuel into the furnace by means of a continuous
rut or screw running from end to end along the outside of same and discharges
the clinker by means of a continuous rut or screw running in the opposite direction
right through the centre of the grate, in other words, the outside of the grate
screws the fuel into the furnace and the inside of the grate screws the clinker out
of the face, thus a continuous supply and discharge is continually being effected
by mea. of the grate revolving in any one given direction. The revolving grate
s so con ructed that it can be utilized for either heating water or generating
team superheating the air before it comes into contact with the fuel i.e. a series
f pipes can be arranged to run from end to end of the revolving grate, whereby
er or air can pass from end to end of same and thereby become heated. By
aid arrangement the grate is preserved by the water or air, or both, keeping down
he temperature of the grate or preventing it becoming so hot as to be destroyed
y the excessive heat from the fuel. The grate can be made or cast in one piece
ith the pipes laid into the mould and the metal run round them, or built in
eparate sections if so desired.
he w
The fuel is fed by means of elevators to a hopper for receiving same and dropped
to the upperside or top part of the grate for the purpose of being conveyed into
e furnace. The grate can be suspended from the front of the boiler or fixed right
front of same and worked or caused to revolve in various ways.
November 5th 1890.

page_text: COMPLETE SPECIFICATION.
Improvements in Mechanical Stokers and Furnaces.
I, WILLIAM FRASER, of 99, Anderton Road, Sparkbrook, Birmingham,
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:-
The object of this invention is to mechanically supply fuel for combustion to
furnaces of any kind or description, and particularly for the furnaces of land and
marine boilers, and also for the purpose of automatically supplying fuel and
discharging the clinker (arising from same) by one motion or movement; i.e. the
fuel is forced into the furnace and gradually moved forward by means of the
external or outside shell of the appliance, and the clinker is conveyed and forced
out of the furnace through the internal part of same.
It is also to be stated that this said appliance or grate is circular in form, and it
is utilized for superheating the air required for combustion, and also for generating
steam or heating water between outer and inside shells of the appliance or grate
(the same being jacketted), thereby effecting a thorough circulation of the water
throughout the boiler, partly by means of the circulating power of the appliance,
and partly by means of the ashpit being converted or turned into a furnace. The
fire is all round the tube both top and bottom, thereby increasing the heating
surface in the furnace nearly one hundred per cent. and causing the water in the
bottom of the boiler to circulate in consequence of its being subjected to intense
heat.
Figure I. of the accompanying drawings represents in vertical section, partly in
elevation, a steam boiler and furnace fitted with the new appliance.
Figure II. is an end elevation of same.
Figure III. is a side elevation of the appliance without the fittings.
Figure IV. is a side elevation of the interior of Figure 111., and
Figure V. is an end elevation of Figure III.
Figure VI. is an end elevation of the packing glands.
The same reference letters and figures are used on the same or equivalent parts
in the various drawings shewn.
In Figure I., a is the boiler, is the hopper for receiving the fuel, a' is the boiler
furnace tube in which the revolving grate is placed (the part of the boiler in front
of same being removed). c is the circular or revolving grate, the shell of which
constitutes a right hand screw, a part of which is removed for the purpose of
shewing the interior of same. c' is a left hand screwed tube running from end to
end of the grate, and c is another left hand screwed tube running from end to end.
d is a bracket for supporting the grate. d' and d2 are the two bearings for the
grate to revolve upon. e and el are two rings with packing glands and inner water
grooves, one for supplying the grate with water, and the other for conveying it
from same to the boiler. is a toothed wheel for causing the grate to revolve, and
gears with which is a worm wheel. 2 in Figure II. is a spindle for driving
same. is the driving pulley, and is the driving strap. e² and e³ are packing
glands for the supply and delivery pipes. d³ and d are the bolts for securing or
holding the bracket d in position. g is an outside casing which is attached to and
secured to the bracket d. h, h, 2 and are curved wings which revolve along
with the grate inside the casing g, and force the fuel into the furnace as it drops
from the hoppers b.
By this arrangement it will be seen that the grate is so constructed, that the
fuel (which is delivered by means of elevators or by hand or otherwise into the
hopper 6) falls by its own weight into the casing g, it is then forced into the furnace
or tube a¹ by the wings h, h¹ and ³, which resemble in shape the blades of a ship's
propeller. The screwed part c keeps working the fuel forward and keeping it

page_text: arwitys
on the move, until it is ultimately consumed. The rubbish or clinke
accumulates at the end of the grate e until high enough to fall into the centre
the grate, i.e. the interior of the inner tube c. It is then worked backwards b
means of the inside screw on c', where it can be allowed to accumulate until th
5 inside screw is nearly full by having the outside end fitted with a cap to preven
the rubbish from falling out until the clinker is cold and the heat extracted from th
same.
C
The first inside shell c² of the grate is of sufficient distance from the outside
shell c to allow water to circulate freely between them (see Figure 1.). The lefi
10 hand screw on c² can either be made by indenting the casing, or it may be first
made and afterwards fixed to same. The centre casing c¹ is sufficiently far apart
from 2 to admit of a sufficient supply of air for the fuel.
The air for heating the fuel can either be distributed through the space
between the shells c' and 2 (Figure III.), or discharged through apertures in the
5 end of the grate (where the three shells cel care joined together). The thread
in c' can be made similar to c², if desired. The bracket d supports the grate by
means of the bearings at each end and marked d¹ and respectively.
The spur wheel is the driving wheel and is worked by the worm wheel
marked. The grate, when at work, revolves very slowly, the bearings with
packing glands marked e and e¹ remain stationary, one supplying the water to the
grate, and the other discharging it into the boiler. The pipes marked *, in
Figure IV., convey the cold water between casings c and c² to the very end of the
grate. It will thus be seen the water has to travel all the way from the inside end
of the grate to the outside end of same before it can make its exit from the said
grate, the objects being to obtain perfect circulation throughout the grate and to
prevent the grate from being burned or destroyed by the heat.
C
The grate can be raised or lowered to any extent required by means of a screw
or any other suitable appliance attached to the bracket d, the packing glands for
that purpose being so arranged that the feed and discharge pipes will adjust them-
selves to the lowering or raising of the same.
although the driving spindle and worm wheel are placed in a horizontal position,
It will also be observed that
they can be placed in a vertical position or driven in any other suitable way.
с
The outside casing y is fitted all round c and is provided with perforated doors
for the purposes of admitting air into the fuel in the furnace, and giving access to
the furnace when required.
No alteration whatever in the present boilers or tubes is required if this
invention is adopted, the outside casing 9 being cast with a deep flange for the
purpose of making a joint when placed against the boiler; i.e. the appliance is so
constructed, and made complete in itself, that the old furnace fittings in any boiler
can be removed and the new appliance placed inside the tube, the casing y being
placed against the boiler, and the bracket d fixed or attached by means of bolts to
the floor in front of the boiler.
The grate can be constructed in various ways. For example, the outside shell c
can be made by the metal being forced out by means of a male and female dic, or
by any other suitable process, or a male model of the grate can be made with
ufficient taper that copper can be deposited on same to whatever thickness
equired and removed from the male part after the depositing process is completed.
It will thus be seen that the part of the grate which is subjected to the heat can
e made in circular form to any required pitch, and all in one piece, either in
opper, or iron, or mild steel, or any other suitable material.
ell
Other modifications of my invention are shewn in Figures VII., VIII., and IX.,
e only difference to that above described being in the construction of the grate
C which is made of different shapes to the one already described. That is,
ere is a gradual taper on the body of the grate shell c from the driving spur
heel at the front of the boiler, to the end of the grate. The wings marked h
d in Figures VIII. IX. respectively are parallel from end to end.
The inside of this grate is fitted and constructed as in Figures I
If III

page_text: and IV., but in other respects is exactly similar thereto. The water circulates
between the outside and inside shells, while the fuel is fed and the clinker auto-
matically discharged by the one motion or movement, the fittings and gear outside
the boiler being the same as already described and set forth.
It will be observed that if the interior of the grate, as shown in Figure VII.,
were removed, and nothing but the jacketted part left, the clinker or rubbish would
gradually work itself out without the assistance of the screwed parts, on account
of the taper gradually increasing from the inside to the outside end of the grate,
and that the cost of production would be thereby reduced considerably.
Figure VIII. is an end elevation of the grate shell e shewn in Figure VII., and
Figure IX. is a modification of Figure VII, being different in shape only.
Another modification of said invention, could be constructed in simply casting
the revolving grate with a series of pipes running longitudinally through the
casting from end to end of the grate and connected altogether at the outside end
of same, or in having a return pipe coil with the grate cast round same. Either of
the two latter modifications would preserve the grate and act as a water heater and
steam generator, but I would give the preference to the others.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. A revolving furnace grate having an external right
or
or
and
left hand screw, and
with internal right left hand screw (such as shown in Figures L., III., IV., and
and
marked c¹ and e²), the former for the purpose of feeding or moving the fuel forward
into the furnace, and the latter for the purpose of removing the rubbish or clinker
from the furnace; substantially as above set forth.
2. revolving grate, the outside shell of which is either a separate piece, or
made in conjunction with an inside shell (2); for the purposes set forth.
3. A jacketted grate adapted to heat and circulate water or generating steam,
and supported by means of a bracket or brackets, either supported from the boiler
or attached to the floor or ground in front of same, as shewn in Figures I. and II.,
and marked 3 and 4, with driving spur wheel with worm wheel and gear, and
marked fffff, and with packing glands e and e' and stuffing boxes e³ and e³;
all for the purposes described.
4. A grate having a casing (as shewn in Figure 1.) and curved wings
marked h, h, 2, 3, as shewn in Figures II. and 1V., for the purpose of feeding or
forcing the fuel into the furnace; as set forth.
5. A grate having pipes et running from end to end thereof for the purpose of
conveying the water to the end of the grate; as set forth.
6. A revolving grate (as shewn and marked c in Figure VII.) tapered externally
and internally as set forth for the purposes mentioned.
;
7. A grate having parts as above described (including Figure IX.) wherein the
fuel is all round the tube or tubes of the furnace, whereby the heating surface in
same is increased and the fuel is fed and the clinker automatically discharged; as
set forth and also as shown in the various figures of the accompanying drawings.
Dated the 5th day of August 1891.
WILLIAM FRASER.