Improvements in Mechanical Stokers and Furnaces.
Year: 1896

page_text: Date of Application, 21st Dec., 1896-Accepted, 20th Mar., 1897
Improvements in Mechanical Stokers and Furnaces.
I, ISAAC SHIMWELL MODOUGALL, of High Bank, Didsbury, in the County of
Lancaster, Manufacturer, 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 :-
My invention relates to all furnaces in which coal is consumed as fuel, but is more
particularly applicable to boiler furnaces in which mechanical stokers and moving
fire bars are used.
My invention consists in a number of detail improvements in the construction of
these furnaces whereby smoke consumption, economy in fuel, durability of fire bars,
and easy regulation of the feed, are secured and the general efficiency of the furnace
over those now in use, is increased.
The different modifications and improvements constituting my invention are
illustrated in the accompanying five sheets of drawings in which
Figures 1 and 2, Sheet 1, are respectively part end view and longitudinal section
through a "Lancashire" boiler showing my improved steam jet applied in the furnace.
Figures 3, 4 and 5, Sheet 2, are respectively cross section, plan, and elevation of the
swivel coupling used in my improved steam jet.
Figures 6 to 11, Sheet 3, inclusive, illustrate an improvement on the coking snog
or plate used in mechanical stokers. Of these, Figures 6 and 7 are cross sections,
while Figures 8 and 9 are respectively end elevation and plan of the improved snog.
Figures 10 and 11 are end elevation and plan of the snog without the improvement.
attached.
Figures 12 to 15 inclusive, Sheet 4, illustrate improvements in fire bars.
Figures 12, 13 and 14 are respectively vertical section, plan and sectional end view,
showing the improved fire bars in a furnace in section, while Figure 15 shows details
of the bars on a larger scale.
Figures 16 and 17, Sheet 5, are respectively front elevation and cross section of an
improvement on my well-known coking stoker for easier regulation of the damper
and fuel fed on to the coking snog or plate and fire bars.
Referring now to the first portion of my invention illustrated in Sheets 1 and 2, my
improvement, as applied to a Lancashire boiler, Figures 1 and 2, is as follows:-
From the valve inounting block A or other suitable source of supply I lead two
small bore steam pipes B B, one to each furnace. These pipes B B have fitted on
them the steam admission valves C C, and drain cocks or valves D D to blow off
the condensed water before starting the steam jet. Fixed to the pipes B B by the
usual connecting pieces, and about the position shown in the drawings, I place swivel
joints EE hereinafter described in detail. These joints have fixed within them steam
pipes FF so placed that they come underneath the fire bars G. I perforate these
pipes G G at one side, and as they are capable of adjustment, it is evident that the
steam may be directed at any angle relatively to the fire bars. The swivel joint G
is shown in detail on Sheet 2. It consists of a conical plug pipe H ground into
and rotating within a plug body or chamber I. The body I and plug H are recessed
at J forming an annular space, and this space J always communicates with the steam
space by the passage and pipe K. The plug H has a solid and open end.
solid end it is screwed and carries the usual fitting for making a steam joint, while
at the open end it carries the perforated pipe F hereinbefore referred to. Suitable
At the

page_text: ports such as M make the interior of the plug H always communicate with the
annular space J. It is evident that by this arrangement I have a series of steam
jets underneath the fire bars, which I can control both as to direction and quantity,
and 1 find that by being able to do so the varying conditions in boiler furnaces as
to quality of coal, insufficiency of draught, overheating of fire bars, etc., can all be
easily coped with.
Referring to the portion of my invention illustrated in detail in Sheet 3,
Figures 6 to 11 inclusive, and also shown in section with a furnace on Figure 2,
Sheet This improvement in furnaces applies to that class of stokers known as
coking," with moving fire bars, in which the fuel is fed on to the bars from a hopper
immediately in front of a coking snog or snogs. These snog plates have a coking
action upon the fresh fuel from the hopper and also keep it ignited while the moving
bars gradually travel the fuel towards the back and also distribute it. I have found
that with this old arrangement a loss of green coal dust or slack sometimes takes place
through the fire bars immediately in front of the snogs, and also that the iguition of
fresh fuel is not complete enough. To overcome these difficulties 1 form an extension
of the ordinary snog, and this extension snog plate is constructed and applied as
follows;-
Referring to Sheet 3 Figures 6 and 7 are vertical cross sections, N is the old snog,
and the extension snog. The extension snog O may be made either straight as
at P. Figure 7, or curved, as at Q, Figure 6, according to the nature of the fuel used,
and I construct them with suitable perforations R R arranged symmetrically over
their whole area. This is clearly seen on end elevation and plan, Figures 8 and 9.
These perforations admit air. The application of this improved extension snog to
the older one N is shown in situ in a furnace at Figure 2, Sheet 1, and their relative
position to the moving fire bars G is clearly defined.
By this device I secure better ignition and coking of the fresh fuel, and save any
loss through the green coal dust or slack falling directly through the air spaces of the
fire bars.
Referring now to that portion of my invention relating to improvements in fire bars
illustrated on Sheet 4, Figures 12 and 14 show respectively a longitudinal section and
sectional end view of a furnace with moving fire bars S. I sometimes make these hars
in two lengths T, U, and couple them together by a joint V which permits of easy
attachment, while still holding the bars together firmly enough to transmit the
to and fro motion. This joint V may be made in various ways, and at Figure 15
I show three other methods of doing this, numbered 1, 2 and 3. Nos. 1 and 2 are
simple male and female jaw pieces a and b, while No. 3, shown in plan and elevation,
consists in forming small projections d d on one bar end, and corresponding recesses
in the other bar end, the two bars also half check together.
The moving bars S rest at their inner ends W on a small roller X fixed in a cross
bracket Y, and that end W is cut at an angle where it rests on the roller X so that
simultaneous with the two and fro horizontal motion of the fire bar a slight vertical
one takes place also. As the har is in two portions T U joined at V, it is ovident that
it must he supported at the point of junction, and to do this I form the end Z of the
portion V with a similar angle, and rest it on a roller X fixed into a cross bracket Y'.
The cross brackets Y and Y rest upon the furnace sides, and are fastened together by
the tie rods e e.
The brackets Y Y have openings left in them so that the clinker
and ash may be withdrawn along the furnace bottom in the usual way. For keeping
the fire bars in a vertical position I cast a series of hemispherical projections g g about
hali way down the bar. The fire bars S may be made in one section, as shown in plan
at Figure 13, and they also may be made in any suitable number of sections, one
of the joints hereinbefore described being used along with a similar cross bracket to Y
for every section. By thus having the bars in sections a light thin durable bar can be
made, and the ends can be readily chilled when making.
Referring to another portion of my invention illustrated on Sheet 5, Figures 16 and 17
are respectively, front elevation and cross section through the hopper part of my
well-known mechanical coking stoker. About the point A, Figure 17, the coal passes

page_text: from the hopper down into the furnace, and the feed is regulated by the damper plate B
being raised or lowered. My improved method of doing this consists in arranging a
cross shaft C parallel with the damper B, and carrying two cog wheels D D' upon it.
These cog wheels gear into two racks E E¹ fixed to the damper. A side shaft F
running in bearings carries a worm G which gears into a suitable worm wheel H
carried upon the cross shaft C. Upon rotating the hand wheel I the damper B
is raised or lowered easily by the attendant from the boiler foot plate thus regulating
the fuel feed.
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. In mechanical and hand stoking furnaces arranging a steam jet so that the angle
of the jet relatively to that of the fire bars may be altered easily all as hereinbefore
described with reference to Figures 1, 2, 3, 4 and 5 of the accompanying drawings.
2. In mechanical and hand stoking furnaces the arrangement and construction of the
swivel joint for steam jets as hereinbefore described, with reference to Figures 3, 4 and 5
of the accompanying drawings.
3. In mechanical stokers of the coking type forming an extension of the usual
coking snog or plate as and for the purpose described.
4. In furnaces having moving fire bars forming the bars in two or more sections
joined together substantially as hereinbefore described.
5. In furnaces having moving fire bars forming on them semi-circular projections
such as g, Figures 12 and 14, as and for the purpose described.
6. In furnaces having moving fire bars in two or more sections, connecting these
sections by the joints hereinbefore described and illustrated with reference to
Figures 12 and 15 of the accompanying drawings.
7. In mechanical stokers of the coking class the particular arrangement for regulating
the fuel feed, herein before described and illustrated with reference to Figures 16 and 17
of the accompanying drawings.
Dated this 19th day of December 1896.
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents.