Improvements in Air-doors for Furnaces.
Year: 1897

page_text: Date of Application, 17th May, 1897
Complete Specification Left, 17th Feb., 1898-Accepted, 2nd Apr., 1898
Improvements in Air-doors for Furnaces.
I, ROBERT CRANE, of 46, Sharsted Street, Kennington Park, London, S.E.,
Engineer, do hereby declare the nature of this invention to be as follows:-
My invention relates to furnaces employed for the construction of fuel of any
kind and consists of improvements applied to such furnace doors whereby a
regulated admission of heated air may be obtained in an exceptionally advan-
tageous manner to ensure the more perfect combustion of the fuel and the
prevention of smoke.
To carry my invention into effect I provide the door of the furnace which may
be hinged to the furnace front in the usual way with a flat faced chamber pro-
jecting outwards and in the flat face of this projection I pierce a large number
of air-holes preferably towards the upper part of such face for admitting air
direct to the furnace.
These holes are countersunk or enlarged on the inner face so as the better to
diffuse or spread the air admitted through them.
Within the said projecting chamber of the door I suspend a hanging inner
shield or pad by means of hook hinges over projecting studs in the sides of the
said chamber so that the said hanging shield pivots on the said upper hinges
and when in its lowest position makes a fair joint upon an oblique seat on the
inner side and bottom faces of the said projecting chamber.
In order to retain a partial side joint when the hanging shield is partially
lifted or when it is warped I may provide projecting side flanges or ribs on the
said shield which drop within the said oblique faces of the door chamber.
I preferably slightly curve the said shield in a direction away from the door
and I provide the face of the shield receiving the impact of the air through the
said perforations with serrations to increase the surface of the said shield pre-
sented to the air so that it may impart a large amount of heat to the air before
it enters the furnace.
I may also curve the said serrations to the outer edges of the shield to cause
the impinging air to diverge to the sides as well as to the bottom of the shield.
I affix a pivotted handle to the said shield passing outwards through the door
and provide steps or a ratchet face on the under side of such handle where it
that when the shield is lifted by the
rests on the hole through the door so
said handle from resting at its bottom and side edges upon the oblique face of the
floor the shield may be held at such angle as is desired by the said ratchet
steps of the handle.
By my arrangement as above described the amount of air admitted direct to
the furnace may be easily regulated and such air is heated to a high point by
impingement upon and contact with the said heated shield and is caused by its
disposition and by its serrations to issue direct to the dead-plate of the furnace

page_text: from the lower edge and also from the lower sides of the said shield conferring
the advantages before recited.
Dated this 17th day of May 1897
FELL & JAMES,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.
improvements in Air-doors for Furnaces.
I, ROBERT CRANE, of 46, Sharsted Street, Kennington Park, London, S.E.,
but now of 3, Harmsworth Street, Kennington Park, 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 relates to furnaces employed for the combustion of fuel of any
kind, and consists of improvements applied to such furnace doors, whereby a
regulated admission of heated air may be cbtained in an exceptionally advan-
tageous manner, to ensure the more perfect combustion of the fuel and the
prevention of smoke.
To carry my invention into effect, I provide the door of the furnace, which may
be hinged to the furnace front in the usual way, with a flat faced chamber pro-
jecting outwards, and the flat face of this projection, I pierce a large number
of air-holes preferably towards the upper part of such face, for admitting air
direct to the furnace.
These holes are counter-sunk or enlarged on the inner face, so as the better to
diffuse or spread the air admitted through them.
Within the said projecting chamber, of the door, I suspend a hanging inner
shield or pad, by means of hook hinges, over projecting studs in the sides of the
said chamber, so that the said hanging shield pivots on the said upper hinges,
and when in its lowest position makes a fair joint upon an oblique seat, on the
inner side and bottom faces of the said projecting chamber.
I further bring round the perforated front plate of the door, into a curved
pocket at the top of the door, the lip of the said pocket forming the support on
which the inner plate or pad pivots by means of two or more hooked hinges. The
inner face of the said pocket is also perforated with small holes through which
hot air is admitted over the fire, the air being heated by passing through the
inner face of the said pocket before it enters the furnace.
In order to retain a partial side joint, when the hanging shield is partially
lifted or when it is warped, I may provide projecting side flanges or ribs, on the
said shield, which drop within the said oblique faces of the door chamber.
I preferably slightly curve the said shield in a direction away from the door,
and I provide the face of the shield receiving the impact of the air through the
said perforations with serrations to increase the surface of the said shield pre-
sented to the air, so that it may impart a large amount of heat to the air, before
it enters the furnace.
inay also curve the said serrations to the outer edges of the shield, to cause
the impinging air to diverge to the sides, as well as to the bottom of the shield.
I affix a pivotted handle to the said shield, passing outwards through the door,
and provide steps or a ratchet face on the under side of such handle, where it
rests upon the hole through the door, so that when the shield is lifted by the
said handle from resting at its bottom and side edges upon the oblique face of the
floor, the shield may be held at such an angle as is desired, by the said ratchet
steps of the handle.

page_text: By my arrangement as above described the amount of air admitted direct to
the furnace, may be easily regulated, and such air is heated to a high point by
impingement upon, and contact with, the said heated shield, and is caused by its
disposition and by its serrations to issue direct to the dead-plate of the furnace,
from the lower edge and also from the lower sides, of the said shield conferring
the advantages before recited.
And in order that my invention may be the better understood, I now proceed
to described the same with reference to the drawings hereto annexed, and to the
letters and figures marked thereon.
Fig. 1 is a vertical transverse section through my furnace doors and chamber.
Figure 2 is a half sectional front elevation of the same with half of the front
plate removed.
Figure 3 is a sectional plan of the same.
A is any suitable furnace-door frame, to which is hinged my door B, which
consists of an outer flat-faced chamber C, of which the front wall or plate is
perforated with holes 1) or apertures, small externally but counter-sunk inside to
better diffuse the air passing through them. This outer plate is curved at its
upper end and turned in upon itself forming a chamber E of which the inner lip
forms a point of support, on which is pivotted the hanging inner plate or pad F.
Such chamber E receives the outer air through small holes & pierced in the
upper part of the chamber casing C which striking against the inner convoluted
face E of the chamber, is allowed to pass through such heated inner face E¹ above
the fire through the holes G pierced in such inner face of the chamber E.
The air so admitted is heated to a high temperature before admission to the
furnace and is admitted in such a position as to ensure the entire combustion in
the furnace of smoke or only partially consumed gases of combustion from
the fuel.
The hanging plate or pad F, when in its lowest position makes a fair joint upon
the under projecting ledge H of the door and upon the curved side ridges or
flanges of the said door.
The plate is curved in the vertical plane, in a direction away from the door,
and is also slightly concave towards the furnace in the horizontal plane and the
outer face towards the perforated outer plate C is corrugated vertically with
splayed curves K towards either side, so that the metal surface presenting to the
impact of air from the perforations of the front plate C is as large as possible and
the divergence of the corrugations tend to direct the air to the sides of the shield
as well as underneath it.
For the regulation of such shield or pad F, I attach thereto a handle L pivotted
at. The handle passes through a slot M in the outer plate Cresting by its own
weight upon the bottom of such slot. On the under face of the said "handle I
provide serrations N, so that when the handle is thrust inwards, the pad F is
lifted from its lower and side joints and the handle will engage with the slot in
the front plate C by one or other of the said serrations, adjusting the lift or angle
of the pad of plate F as may be desired.
Having now particularly described and ascertained the nature of this said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1st. A furnace door consisting of, in combination, a front chamber with outer
perforated plate, having pivotted thereon, within the said chamber, a corrugated
inner pad or shield, resting by gravity normally upon a fairly jointing seat at the
bottom edge and around the sides, and adapted by a notched handle passing
through the front plate, to be fixed at any desired angle from the said seat sub-
stantially as and for the purpose described.
2nd. In a furnace door, having a front chamber perforated plate, and a hanging
internal and adjustable shield pivotted within said chamber, an extension of said
front chamber plate convoluted inwards, forming, by perforations in opposite

page_text: faces, a fixed air heating chamber in said door and serving also as regards its
inner edge as a supporting means to said pivotted shield, substantially as and for
the purposes described.
Dated this 17th day of February 1898
FELL & JAMES,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.