Improvements in Steam Boiler and other Furnaces having Forced Draughts.
Year: 1886

page_text: Date of Application, 13th Aug., 1886.
Complete Left, 7th May, 1887.
Complete Accepted, 7th June, 1887.
PROVISIONAL SPECIFICATION.
Improvements in Steam Boiler and other Furnaces having
Forced Draughts.
We JOHN, SAMUEL WHITE of East Cowes Isle of Wight Ship Builder and GEORge
EDWARD BELLISS of Ledsam Street Works Birmingham in the County of Warwick
Engineer and Boiler Maker do horeby declare the nature of this Invention to be
as follows:-
The application of forced draughts that is draughts made by blowing by means of
a fan or otherwise into the ash pit of furnaces without the intervention of a closed
stokehold has been found subject to inconveniences as the said furnaces have been
constructed hitherto and the object of our invention is to improve and simplify the
arrangement of the furnace and its appliances so as to remove or diminish the
inconveniences referred to. We will describe our invention in connection with a
steam boiler furnace having a fan blast.
We force air by means of a fan driven by the main or a separate engine direct
into the ashpit the door of which is hinged to act as a non return flap to prevent the
escape of the air into the atmosphere. To prevent the possibility of a back draught
with the attendant risk to the stoker when firing as well as the annoyance occasioned
by the heat from the of small ashes and gas through the joints of the door we employ
a casing enclosing the mouth of the furnace and in this casing an outer door in front
of the ordinary furnace door. The outer door is maintained in its closed position by
means of a bolt connected with a sliding flap used for shutting off the air from the
fan orifice. When the said flap is in such a position that the fan orifice is uncovered
the bolt described bears against the front of the outer door and the said door cannot
be opened. When however the sliding flap is brought over the fan orifice the said
bolt is withdrawn from the front of the door and the door can be opened. By this
arrangement it is impossible for the furnace door to be opened whilst the fan is in
operation and as the ashpit is also in connection with the space between the two
furnace doors the opening of the outer door will at once get rid of any excess of
pressure which might be in the ashpit after the fan is closed off by leakage or
otherwise.

page_text: Instead of closing the orifice of the fan by a sliding flap a jointed or hinged flap
may be employed in conjunction with the double door arrangement. This hinged
flap carries a cam and the axis of the outer door of the double door also carries a cam.
These cams have such a figure and are so arranged that when the doors are closed the
door cam is moved beyond the range of the fan flap cam and the said flap can now
be raised and the doors can no longer be opened the door cam being blocked by the
position into which the flap cam has been brought. On shutting down the fan flap its
cam is brought into such a position that it does not interfere with the motion of the
door cam and the doors can consequently be opened.
The outer door is weighted so as to fall open when it is at liberty to move.
Or the cams may be employed on the two doors the outer door being in this case
on the same axis as the fan flap both moving together but the fan flap being connected
to the outer door by a spring arm there is a slight elastic play allowed between the
outer door and fan flap. The cam on the inner door is so situated and has such a
shape that when the outer door and fan flap are raised the cam on the outer door
blocks the cam on the inner door and the latter cannot be opened. When however
the outer door has been brought into a horizontal position and the fan orifice closed
by the fan flap the cam on the outer door is in such a position that it no longer blocks
the cam on the inner door and the said inner door can be opened.
The outer door in each arrangement has a catch to retain it in its closed position.
To prevent the necessity for a door in the ash pit to remove the ashes accumulating
behind the bridge which door would render probable a leakage of cold air past the
tube plate we provide one or two large tubes below the ordinary boiler tubes to enable
the ashes to be raked out through a small door in the smoke box.
These tubes also improve the circulation and add to the effective heating surface.
Dated this Thirteenth day of August 1886.

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We JOHN SAMUEL WHITE of East Cowes, Isle of Wight, Ship Builder and GEORGE
EDWARD BELLISS of Ledsam Street Works Birmingham in the County of Warwick
Engineer and Boiler Maker, do hereby declare the nature of our Invention and in
what manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
The application of forced draughts (that is, draughts made by blowing by means of
a fan or otherwise into the ashpit of furnaces) without the intervention of a closed
stokehold has been found subject to inconveniences as the furnace fittings have been
constructed hitherto and the object of our invention is to improve and simplify the
arrangement of the furnace appliances so as to remove or diminish the inconveniences
referred to.
We will describe our invention in connection with a steam boiler furnace having a
fan blast.
We force air by means of a fan driven by the main or a separate engine direct into
the ash pit the door of which is hinged to act as a non-return flap to prevent the
escape of the air into the atmosphere. To prevent the possibility of a back draught
with the attendant risk to the stoker when firing as well as the annoyance occasioned
by the heat from the escape of small ashes and gas through the joints of the door,
we employ a casing enclosing the mouth of the furnace and in this casing an outer
door in front of the ordinary furnace door. The outer door is maintained in its
closed position by means of a bolt passing through a slot in the hinge of the
outer furnace door and connected with a sliding flap used for shutting off the air from
the fan orifice. When the said flap is in such a position that the fan orifice is
uncovered the bolt described locks the hinge and bears against the front of the outer
door and the said door cannot be opened. When however the sliding flap is brought
over the fan orifice the said bolt is withdrawn and the door can be opened.
This part of our invention is illustrated in Figures 1, 2 and 3 of the accompanying
Drawings, Figure 1 representing in plan; Figure 2 in front elevation and Figure 3
in longitudinal vertical section a steam boiler furnace with which our improved
appliances are combined.
The same letters of reference indicate the same parts in Figures 1. 2 and 3.
a is the furnace; b the ash pit; the ash pit door which closes by its own weight
and acts as a non return flap and o is the casing enclosing the mouth of the furnace;

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b
d is the ordinary furnace or fire door and e is the outer door in the casing c in front
of the ordinary fire door d (see Figure 1). The outer door e in the casing c is
jambed tight by means of the lever catch and the two furnace doors d and e are
connected together by the jointed arm g so that the two doors are simultaneously
opened and closed; h is the fan case containing the fan the shaft i of which is driven
by the main engine or by a separate engine. The fan case h is in direct communi-
cation by means of the casing c at the mouth of the furnace with the ash pit 6 (see
the section Figure 3) ; & is the fan orifice and 1 is the sliding flap or fan door used for
shutting off the air from the fan orifice. The said fan flap is moved by the handle
and its upper and lower edges work in the guides m, m on the fan case h the said
guides carrying anti friction rollers upon which the said edges of the fan flap bear
(see Figure 2). At the front of the sliding flap - is a bolt n for bolting the outer
door e when the said flap is in its withdrawn position and the fan orifice k is
uncovered. The said bolt n passes through a slot in the hinge of the outer door e and
bears against the front of the said outer door as represented in continuous lines in
Figures 1 and 2.
When the sliding flap or fan door is moved into the position indicated in dotted
lines in Figure 2 the fan orifice k is closed and the bolt n.is withdrawn from the front
and joint of the door e and the said door can be opened. By this arrangement it is
impossible for the furnace door to be opened whilst the fan is in operation and back
draught is thereby prevented and as the ashpit is also in connection with the space
between the two furnace doors the opening of the outer door will at once get rid of
any excess of pressure which might be in the ash pit after the fan is closed off by
leakage or otherwise.
Instead of closing the orifice of the fan by a sliding flap a jointed or hinged flap
may be employed in conjunction with the double door arrangement. This hinged
flap carries a cam and the axis of the outer door of the double door also carries a cam.
These cams have such a figure and are so arranged that the fan flap can be opened
only when the furnace door is closed and the furnace door can be opened only when
the fan flap is closed. The outer door is weighted so as to fall open when it is at
liberty to move and has a catch to retain it in its closed position.
This arrangement of our invention is illustrated in longitudinal vertical section in
Figure 4 of the drawings. In the said Figure 4, a is the furnace; 6 the ash pit;
62 the ash pit door or non return flap and c the casing at the mouth of the furnace;
d is the furnace or fire door and e is the outer door in the casing c the two doors d
and e being connected together by the jointed arm g. The axis of the outer door e is
weighted at e so that the said door falls when the lever catch is lifted off the said
door; p is the cam on the axis or hinge of the outer door e; q is the hinged
flap by which the orifice of the fan is opened and closed, the axis of the said
hinged flap being provided with a cam . The said hinged flap q is weighted
at r. In the drawing the two doors d, e are represented closed and the fan
flap q open and the fan orifice uncovered. When the parts are in the positions
represented the cam q³ of the fan flap q is engaged with the camp on the outer
door e and the said outer door cannot be opened. In order to open the double
door d, e the fan flap q is first raised into a vertical position so as to close the fan
orifice. By this motion of the fan flap q its cam is removed out of the range of the
cam p on the outer door e and the two doors can be opened by releasing the jambing
catch from the weighted outer door e. After the two doors d, e have been closed
and the outer door e fastened by the jambing catch the fan flap is brought
into the position represented in the drawing. The fan orifice is thereby uncovered
and the outer door e prevented from being opened by the cams 4*, p until the
fan flap has been raised and the fan orifice covered as hereinbefore explained.
Or the cams may be employed on the two doors, the outer door being in this case.
on the same axis as the fan flap both moving together but the fan flap being
¡ connected to the outer door by a spring arm there is a slight elastic play allowed
between the outer door and fan flap. The cam on the inner door is so situated and

page_text: has such a shape that when the outer door and fan flap are raised the cam on the
outer door blocks the cam on the inner door and the latter cannot be opened. When
however the outer door has been brought into a horizontal position and the fan
orifice closed by the fan flap, the cam on the outer door is in such a position
that it no longer blocks the cam on the inner door and the said inner door can be
opened.
This part of our invention is illustrated in longitudinal vertical section in
Figure 5; a is the furnace; b the ash pit; the ash pit door and c the casing
around the mouth of the furnace as hereinbefore described; d is the inner or
fire door which in this arrangement is independent of the outer door e. On the
inner or fire door d is the cam d and on the outer door e is the can e³ the said
cams and having the shapes and positions represented; q is the fan flap
keyed on the same axis as the outer door e the said fan flap and outer door
moving together. The fan flap q is connected to the outer door e by the spring
arm & the free end of which works in the loop represented on the said outer
door. By this means a slight elastic play is permitted between the outer door e
and the fan flap the amount of flexure in the spring arm being regulated by
the catch t on the outer door. When the inner door d has been closed and the
outer door e and fan flap q have been raised into the positions represented in
Figure 5, the came on the outer door e blocks the cam on the inner door d
and the latter cannot be opened, the bringing of the fan flap into the horizontal
position represented uncovering the fan orifice. Before the fire or inner door d
can be opened it is necessary first to depress the fan flap q into a vertical
position thereby closing the fan orifice. This motion of the fan flap opens the
outer door e and the cam e on the outer door no longer blocking the cam d' on the
inner door d the said inner door can be opened.
In the arrangement Figure 5 the fan case is situated at the lower half of the
casing c while in the arrangement Figure 4 the fan case is situated at the upper half
of the casing c.
To prevent the necessity for a door in the ash pit to remove the ashes accumulating
behind the bridge which door would render probable a leakage of cold air past the
tube plate, we provide one or two large tubes below the ordinary boiler tubes fitted
with loose fitting plugs to enable the ashes to be raked or blown out. These tubes
also improve the circulation and add to the heating surface.
This part of our invention is illustrated in Figures 2 and 3, two large tubes u u
below the ordinary boiler tubes being employed. It will be seen that the said larger
tubes uu open behind the bridge so that the ashes accumulating behind the said
bridge can be removed by raking them out or blowing them through the said tubes,
doors in convenient parts of the smoke box being provided for that purpose.
Although we have represented our improvements in connection with a fan blast yet
our said improvements may be used in connection with a forced draught otherwise
obtained.
Having now particularly described and ascertained the nature of our invention and
the manner in which the same is to be performed we declare that we claim as our
invention of " Improvements in steam boiler and other furnaces having forced
draughts"
First The construction and combination of the double door of the furnace, the
casing enclosing the mouth of the furnace and the ash pit door hinged to act as a non-
return flap for the purposes and substantially as hereinbefore described and illustrated
in Figures 1, 2 and 3 of the accompanying Drawings.
Secondly The arrangement or combination of parts herein before described and
illustrated in Figures 1. 2 and 3 of the accompanying Drawings for shutting off the
air from the fan orifice, or for shutting off the forced draught otherwise obtained,
when the double door of the furnace is opened and for locking the outer door of the
double door when the fan orifice, or the orifice in connection with the forced draught,
is uncovered substantially as described and illustrated,

page_text: Thirdly The arrangement herein before described and illustrated in Figure 4 of
the accompanying Drawings in which the fan or forced draught orifice is opened and
closed by a jointed or hinged flap and the outer door of the double door is locked and
unlocked by the action of cams on the fan flap and the said outer door.
Fourthly The arrangement herein before described and illustrated in Figure 5 of
the accompanying Drawings in which cams are employed on the two doors and the
outer door is keyed to or situated on the same axis as the jointed fan flap, the said
fan flap and outer door moving together substantially as described and illustrated.
Lastly The use of one or more large tubes below the ordinary boiler tubes for
enabling the ashes accumulating behind the bridge of the furnace to be raked or
blown out and thereby dispensing with a door in the ash pit substantially as herein-
beforo described and illustrated in Figures 2 and 3 of the accompanying Drawings.
Dated this Seventh day of May 1887.
W. T. WHITEMAN,
Agent for the Applicants.