IMPROVEMENT STEAM BOILERS
Year: 1879

page_text: LETTERS PATENT to Samuel Cleland Davidson, of Belfast, in the County
of Antrim, Gentleman, for the Invention of
BOILERS"
"IMPROVEMENTS IN STEAM
Sealed the 13th January 1880, and dated the 25th October 1879.
PROVISIONAL SPECIFICATION left by the said Samuel Cleland Davidson
at the Office of the Commissioners of Patents on the 25th October 1879.
SAMUEL CLELAND DAVIDSON, of Belfast, in the County of Antrim, Gentleman.
"IMPROVEMENTS IN STEAM BOILERS."
The improvements relate to what are generally known as upright or vertical
boilers, and apply in particular to those in which the fire box is situated in the
lower end of the boiler and within it. The fire box may be constructed much in
the ordinary way, with preferably its upper surface dome shaped or dished.
The improvements consist in having in the centre of the upper surface of the fire
box an opening of suitable size to permit the passage through it of the products of
combustion from the fire into a combustion chamber placed over and connected to
it, which combustion chamber is quite closed in over the top end, but has perforations;
all round its vertical sides at suitable distances apart, to which are fitted tubes
leading radially and horizontally (or with a slight droop towards the outer ends)
from the combustion chamber across the water space enclosing it, and through
corresponding perforations in the outer shell of the boiler. The tubes are of course,
fitted so as to be water and steam tight at each end. The vertical sides of the
combustion chamber have a wider diameter than that of the opening in the top of
the fire box, but this diameter is less than that of the fire box, and the bottom end
of the combustion chamber is closed in or contracted to form an opening to correspond
with the form and size of the opening in the top of the fire box, and these openings
are connected by means of a suitably shaped ring which forms a short neck or flue
with a water space around it between the fire box and the combustion chamber.
Round the outer shell of the boiler and opposite the ends of the radial tubes from
the combustion chamber there is an annular flue into which the products of
combustion escape from the tubes, and this flue may be constructed so as to jacket
the whole of the upper portion of the boiler, in which case the chimney for carrying

page_text: off the products of combustion from it would be placed over the centre of the upper
end of the boiler; or this flue may be constructed so as to enclose or jacket only
that portion of the boiler where the radial tubes are situated, in which case the
chimney would be to one side of the boiler. When this smoke flue is constructed
to enclose the whole of the upper portion of the boiler, that part of the outer shell
of the boiler which encloses the steam space may be protected on its outer side by
baffle plating against the destructive effects of the hot gases from the fire. That
portion of the outer casing of the smoke flue which is opposite the ends of the
radial tubes is movable in the form of doors or otherwise to allow of the tubes being
easily got at to be cleaned or repaired.
The advantages obtained by this Invention are,-
First. The economy of fuel, which is due to the large area of heating surface
which this arrangement of having a central combustion chamber with the tubes
leading from it placed radially and horizontally around it practically admits of,
combined with the prevention of any waste of heat by the products of combustion
from their development until they have passed through the tubes, owing to the
fire box and combustion chamber being so entirely enclosed by water that whatever
heat is given up by the hot gases until they have passed through the tubes must
necessarily be given up usefully to the water.
Second. The strength of construction which is obtained by having the combustion
chamber connected with the outer shell of the boiler by the tubes fitted radially
around the combustion chamber.
Third. The simplicity of construction of the whole boiler, and the facility with
which the tubes can be got at to be cleaned or repaired.
, SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Samuel Cleland Davidson in the Great Seal Patent Office on the
24th April 1880.
«
SAMUEL CLELAND DAVIDSON, of Belfast, in the County of Antrim, Gentleman.
IMPROVEMENTS IN STEAM BOILERS."
The improvements relate to what are generally known as upright or vertical
steam boilers, and apply in particular to those in which the fire box is situated in
the lower end of the boiler and within it. The fire box may be constructed much
in the ordinary way, with preferably its upper surface dome shaped or dished.
The improvements consist in having in the centre of the upper surface of the fire
box an opening of suitable size to permit the passage through it of the products of
combustion from the fire into the combustion chamber placed over and connected to
it, which combustion chamber is quite closed in over the top end, but has perforations
all round its vertical sides at suitable distances apart, to which are fitted tubes
leading radially and horizontally (or with a slight droop towards the outer ends)
from the combustion chamber across the the water space enclosing it, and through
1

page_text: corresponding perforations in the outer shell of the boiler. The tubes are fitted
into these perforations so as to be steam and water tight.
The vertical sides of the combustion chamber have a wider diameter than that of
the opening in the top of the fire box, but this diameter is less than that of the fire
box, and the bottom end of the combustion chamber is closed in or contracted to
form an opening to correspond with the form and size of the opening in the top of
the fire box, and these openings are connected by means of a suitably shaped ring
which forms a short neck or flue with a water space around it between the fire box
and the combustion chamber.
Around the outer shell of the boiler and opposite the ends of the radial tubes
from the combustion chamber there is an annular flue into which the products of
combustion escape from the tubes, and this flue may be constructed so as to jacket
the whole of the upper portion of the boiler, in which case the chimney for carrying
off the products of combustion is placed over the centre of the upper end of the
boiler; or this flue may be constructed so as to enclose or jacket only that portion
of the boiler where the radial tubes are situated, in which case the chimney would be
to one side of the boiler. When this smoke flue is constructed to enclose the whole
of the upper portion of the boiler, that part of the outer shell of the boiler which
encloses the steam space may be protected on its outer side by baffle plating
against the destructive effects of the hot gases from the fire. That portion of the
outer casing of the smoke flue which is opposite the ends of the radial tubes is
movable in the form of doors or otherwise to allow of the tubes being easily got at
to be cleaned or repaired.
The accompanying Drawings illustrate the construction of my improved steam
boiler.
Figure 1 is a vertical section through the fire box, combustion chamber, and the
contracted neck or flue which connects them together, and through the radial tubes,
annular smoke flue enclosing upper part of the boiler, and chimney.
Figure 2 is a horizontal section through the radial tubes, combustion chamber,
outer shell of the boiler, and the annular smoke casing.
Figure 3 is an elevation.
Figure 4 is a plan of the cast iron foundation frame for carrying the boiler and
fire bars, and enclosing the ash pit.
Figure 5 is a plan showing the points of junction of the connecting stays with
the crown of the boiler and the crown of the combustion chamber. These stays
enable the combustion chamber to resist the downward pressure from the steam
upon it, and at the same time strengthen the crown of the boiler against the pressure
in the contrary direction.
The letters which indicate the several parts are the same in each Figure, and are
as follows:
A, fire box.
B, combustion chamber.
C, neck or flue connecting the fire box with the combustion chamber.
D, radial tubes.
E, casing of the annular smoke flue.
F, chimney.
G, doors in the casing of the annular smoke fluc.
H, door to the fire box.
I, baffle plating.

page_text: cover the crown of the combustion chamber, and of necessity this ensures the radial
tubes being entirely covered with water. The products of combustion from the fire
box pass through the comparatively confined area of the neck or flue C, and
expanding from this contraction into the more roomy combustion chamber B their
combustion is very thoroughly effected therein, and the products of combustion
escape hence through the radial tubes into the annular smoke flue which envelopes
the upper end of the boiler, and in passing through this annular smoke flue over the
upper end of the boiler they to a considerable extent superheat the steam within
the boiler, and eventually escape through the chimney F.
The area of heating surface contained in the fire box, combustion chamber, and
radial tubes is not only very large as compared with the size of the boiler, but its
effectiveness as heating surface is of a high standard, and the fire box and
combustion chamber being practically in the centre of the boiler, and so entirely
enclosed all round by water, it is obvious that whatever heat is given up by the
hot gases after they leave the fire until they have passed through the combustion
chamber and radial tubes must necessarily be given up usefully to the water, and
as the waste heat from these gases after they leave the radial tubes is utilized in
superheating the steam and in preventing radiation of heat from the upper part of
the boiler, the result is a high efficiency as regards economy of fuel.
The radial tubes give great lateral strength to the combustion chamber, and they
are easily got at either for cleaning or repairs by means of the doors G, G, in the
casing of the annular smoke flue.
Having now described the nature of my improvements in steam boilers, and the
manner in which the same is to be performed, I wish it to be understood that I do
not claim the use of radial tubes around the fire box or combustion chamber as in
itself my Invention, but that I claim the combination of a combustion chamber to
which these radial tubes are applied with a fire box to which this combustion
chamber is connected by means of a contracted neck or flue through which the
products of combustion pass from the fire to the combustion chamber, and further
the combination of the same with an annular smoke flue enveloping the upper end
of the boiler, the casing of which flue is fitted with doors opposite the outer ends
of the radial tubes, whereby the tubes may be got at with facility to be either
cleaned or repaired, all substantially as herein before described and represented in
the accompanying Drawings.
In witness whereof, I, the said Samuel Cleland Davidson, have hereunto set
my hand and seal, this Twenty first day of April, One thousand eight
hundred and eighty.
S. C. DAVIDSON. (L.S.)