Improvements in Apparatus connected with Forced or Artificial Draught for Steam Boilers.
Year: 1894

page_text: Date of Application, 14th Feb., 1894
Complete Specification Left, 13th Nov., 1894-Accepted, 15th Dec.. 1894.
PROVISIONAL SPECIFICATION
Improvements in Apparatus connected with Forced or Artificial
Draught for Steam Boilers.
I EDGAR CONISTON MILLS of No. 40 Victoria Buildings Manchester in the
County of Lancaster Consulting Engineer do hereby declare the nature of this
invention to be as follows:-
My invention consists of an improved form of furnace front and ashpit door
combined with improved distributing valves and passages for receiving conducting
distributing and confining the air supply for the furnace.
The main plate of the furnace front is of ordinary form so far as its attachment
to the boiler is concerned which attachment may be of any suitable kind in
accordance with the construction of the boiler. The firing door frame is somewhat
deeper than is usual and it may be cast with the main plate or attached thereto by
bolts or rivets. In some cases I make the main plate of wrought iron. The firing
door is hinged to the door frame externally in the ordinary way and provided with
a latch. In the upper part of the main plate I form an aperture of sufficient area
to pass the quantity of air desired to enter the furnace over the fuel. Centrally
over the firing door I attach a two chambered valve box to the main plate of the
furnace front. The front chamber is the larger and is provided with a suitable
sliding or wing valve to control the air passing to the ashpit. The back chamber
is the smaller and is provided with a similar suitable valve. This chamber com-
municates with the before mentioned apertures in the main plate. The air is
delivered to these two valve chambers by a trunk or pipe from above leading from
the usual fan or other source.
The front chamber is open at its two sides and I attach suitable elbow pipes or
conduits one at each side to conduct the air downwards on either side of the firing
door frame to passages or apertures formed in a horizontal plate formed with the
door frame and being preferably an extension of its floor or dead plate.
These conduit elbow pipes are preferably of a taper form enlarging in width
towards the bottom but being reduced in depth. By suitable hinges I suspend. an
ashpit door to the front of the said horizontal plate. There is no portion or
continuation of the furnace front plate below the bars but if desired I form.
projections or bosses of or on the main plate below the horizontal plate or dead
plate for the purpose of applying the attaching bolts.
The hinged ashpit cover has a circular flange or rim turned inward towards the
boiler front plate and against which it rests when closed. It is so formed that
when closed the door is in an inclined position being nearest to the boiler at the
lower edge. I hold it in its. closed position by means of a hook bolt passing
through the door and hooking on to a suitable stud attached to the ordinary or
inner dead plate. The hook is so formed that when the wing or handle nut is
slackened the hook can be easily disengaged from the front and the ashpit door
opened and held open by a suitable chain and hook.
The air supply for the ashpit is thus conducted by the valve chamber, the two
elbow pipes and the openings in the horizontal plate to the space inside the ashpit
door and the air for the space over the fuel is conducted by the small valve
chamber through the opening in the main plate. Inside and attached to the main.
plate I introduce a suitable baffle or deflector plate having openings inclined
downwards. A narrow opening being also allowed round the edge of the baffle

page_text: plate and between it and the inside of the flue or furnace a thin film of air traverses
the furnace crown and promotes secondary combustion.
The baffle plate serves also to protect the furnace front plate.
The main front plate or a portion of it is continued a short distance below the
bottom of the door frame in order that the inner or usual dead plate may be
secured to it. Or the said usual dead plate may be formed with horizontal flanges
or bosses to allow it to be bolted to the before mentioned horizontal plate
formed with the door frame or front plate or it may be attached in any other
suitable way.
Dated this 13th day of February 1894
COMPLETE SPECIFICATION.
Improvements in Apparatus connected with Forced or Artificial
Draught for Steam Boilers.
I, EDGAR CONISTON MILLS of No. 40 Victoria Buildings, Manchester, in the
County of Lancaster Consulting 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:-
My invention consists of an improved form of furnace front and ashpit door
combined with improved distributing valves and passages for receiving, conducting,
distributing and confining the air supply for the furnace.
In the accompanying drawings
Fig. 1 is a sectional elevation of a boiler furnace front with my improved
apparatus attached.
Fig. 2 is a front external elevation with certain portions removed.
Fig. 2 is a detached view of one of the attachment brackets.
Fig. 4 is a sectional plan view taken through the line ed in Fig. 2, but with a
portion removed from the left hand half view."
In Fig. 3 the left hand half view is a plan view with the overhead air trunk
removed and the right hand half view is a sectional plan taken through the line a b
in Fig. 2.
In all views the same reference letters denote the same parts.
A is the front ring of a boiler furnace. B is the boiler front plate. C is the
dead plate and c represents the bars.
The main front plate of my apparatus is marked D. This may be constructed
as a casting, having the mouthpiece d, the plate d' and under flange d' cast with it
as illustrated, or it may be constructed separately as a wrought or cast plate and
have the parts d, d', and d² attached to it by bolting or otherwise. The plate D is
preferably constructed with lugs d³ fitting as shewn into the hole of the boiler front
plate B.
It may be secured to the front plate B by external snugs or flanges and
bolts in the ordinary way or by internal bolts E taking into brackets e rivetted
inside the furnace tube A as illustrated, the plate D being continued down at the
sides and formed with bosses to receive the bolts E as shewn. The deep cross
rib d' forms in its middle portion the floor of the mouthpiece D and at each side is
formed with openings d'. The lateral under rib d² with the end ribs d³ terminating
below with an angular face d' forms a channel for delivery of air into the ashpit
through the openings d as will be hereafter described. The flange c' of the dead
plate C may be secured to the plate D by bolts. The ashpit door F which in
Fig. 2 is shewn broken off in the left half view is carried by hinges fand bosses d
formed with the plate d'. It is partially of circular form in the lower portion and
is provided all round with an internal rib or flange so constructed as to fit-when
closed to the boiler front plate for a portion of its length and in the upper part to
the plate D and the inclined face de. A hooked bolt G is provided with nut 9, and

page_text: taking internally on to a bolt or stud g₁ suitably attached to the dead plate C.
The hook is so formed that when the handle nut g is slackened the hook can be
easily disengaged from the front and the ashpit door opened and held open by a
suitable chain and hook not shewn in the drawings.
The firing door H is hinged at h in the ordinary way and provided with a
latch h. A sight hole is illustrated but forms no part of my invention.
In the upper part of the main plate D I form an aperture or apertures shewn by
the dotted letters d³ in Fig. 2 and in Fig. 1 of sufficient area to pass the quantity,
of air desired to enter the furnace over the fuel.
Centrally over the firing mouthpiece d I attach a two chambered valve box I to
the main plate D by bolts i as shewn. The front chamber is the larger and is
provided with a suitable valve K. The back chamber is the smaller and is.
provided with a similar valve k. This chamber communicates with the before-
mentioned aperture din plate D. The front chamber is open at its two sides
and I attach to the openings the elbow pipes L L which in turn are attached below
by flanges or snugs and bolts to the plate d'. The pipes L are preferably formed
of a taper form as indicated by dotted lines in Fig. 1 and their lower opening
corresponds and coincides with the openings d in plate d'.
M is the air supply shaft or trunk conveying the air for combustion from a
suitable source such as a fan.
Inside and attached to the plate D I introduce a suitable. baffle or deflector'
plate N having openings p p inclined downwards and allowing a narrow opening
round its edge between it and the surface plate as shewn at n. It is formed with a
flange n' resting against the plate D over the firing hole and for some distance
down its sides. In some case I provide additional holes in this flauge as shewn
at n
The action will be readily understood:
The air entering by the trunk M is split into two currents by the edge, and
regulated or stopped or passed freely by the valves K and k which are provided
externally with means such as the wing screws O and o whereby they may be fixed
in any position. These valves are shewn fully open in Figs. 1. 2 and 3. The
smaller current passing by the channel passes through the apertures do and enters
the space P inside the baffle plate N. Thence it issues by the inclined holes pp in
a downward direction upon the top of the front portion of the fuel and also in a film
through the annular aperture n and passing along the furnace crown promotes
secondary combustion beyond. The currents issuing from p p and n² n² when these
are used, besides promoting combustion serve to protect the firing door H from
the heat. The baffle plate itself also serves to protect the main plate D from
the heat.
The larger air current entering by and controlled by the valve K passes by the
channel and dividing in the lower front part of the box 1 into two currents
passes by the right and left hand conduit elbow pipes L L through the
openings d d in the plate d' into the space below the dead plate and bars and
within the inclined ashpit door F.
Thus both currents can be conveniently controlled or cut off at will by means of
one valve only to each current.
The tapered form of the conduit pipes L and the incline of the ashpit door F
forming a joint against the boiler front plate only in its lower part give a sightly
and compact appearance to the apparatus. The form of the front plate Ď not
extending below the point necessary for attachment by the bolts E and the
separate and attached box I and pipes L combine to form a more simple and
inexpensive construction of the boiler front for forced draught than any hitherto
used.
1 do not confine myself to the exact form or method of construction or
attachment of the front plate D, valve box I, pipes L or ashpit door F, nor to
constructing them as castings. As a modification I may for instance form the
sides of the box I and pipes L solid with the plate D, and attach separate covers,

page_text: or other variations in their construction and attachment may be adopted without
departing from my invention.
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. The combined boiler front for forced draught consisting of a main plate
attached to the boiler and having the furnace mouth, air receiving and distributing
valve box, conduit pipes, ashpit cover, and baffle plates formed with or attached to
it, substantially as and for the purposes hereinbefore described and illustrated in
the accompanying drawings.
:
2. The main plate D having the furnace mouth formed with or attached to it
and combined with the double air receiving and distributing valve box placed over
the furnace mouth fitted with two controlling valves one for the current passing
direct into the furnace over the fuel and one for the current passing into the ashpit
substantially as and for the purposes hereinbefore described and illustrated in the
accompanying drawings.
3. The main front plate D combined with the furnace mouth and air receiving
and distributing valve box and further combined with the attached and tapered
right and left hand conduit air pipes leading the air downwards on each side of the
furnace mouth substantially as and for the purposes hereinbefore described and
illustrated in the accompanying drawings.
4. The main front plate D combined with the hinged and inclined ashpit door
forming a joint against the boiler front plate only at its lower part and secured by
the readily detached hook bolt substantially as and for the purposes hereinbefore
described and illustrated in the accompanying drawings.
Dated this 12th day of November 1894.
EDGAR CONISTON MILLS: