Improvements,in and relating to Steam Boilers.
Year: 1899

page_text: Date of Application,
Oth Oct 1800
Complete Specification Left. 9th Aug.. 1900—Accepted. 9th Oct.. 1900
Complete Specification Left. 9th Aug. 1900-Accepted. 9th Oct.. 1900
PROVISIONAL SPECIFICATION.
Improvements,in and relating to Steam Boilers.
I, WILLIAM SCOTT, of Lyndhurst, 19, Plasturton Avenue, Cardiff, in the
County of Glamorgan, General Manager of the Tydvil Engineering and Ship
Repairing Company, do hereby declare the nature of this invention to be as
follows:
-
This invention relates to a construction of high pressure twin shell boiler
especially adapted on account of its lightness good circulation, and the rapid
and constant production of steam, for shallow draught steamers or where weight
is an important element, and for such craft as cruisers, fast passenger vessels
and so forth, but adapted also for use on land.
A boiler according to this invention comprises two horizontal shells placed
vertically one above the other and connected together by uptake and downtake
pipes or connections, the lower shell containing a furnace flue that extends from
end to end thereof and the upper shell containing horizontal fire tubes that
lead from one end plate of the upper shell to a combustion chamber that is
located at the other end of the upper shell and is in communication with the
furnace flue by a vertical smoke tube.
In one construction of such a boiler, the combustion chamber is of circular
section and located within the rear end of the upper shell and is connected to
the rear end of the furnace flue by a vertical smoke tube of circular section.
The upper end of the smoke tube is flanged for connection to the lower portion
of the combustion chamber, and the lower end of the said tube is plain and
is secured to the top of the furnace tube which is itself flanged upwards to
receive the same. At the points when the smoke tube passes through the upper
portion of the lower shell and the lower portion of the upper shell to connect
the furnace tube to the combustion chamber, a flanged junction or neck-piece
is fitted and securely double rivetted to both shells, the vertical smoke
tube extending through the centre of the junction or neck-piece and being
surrounded by water. The said junction or neck-piece, besides tying the two
shells together, forms the upcast pipe for heated water to pass from the lower
to the upper shell. A downcast pipe is situated at the opposite end of the
lower portion of the upper shell at the smoke box end of the boiler and takes
the form of a T-piece with two outside pipes that extend from said T-piece
to the lower portion of the bottom shell where they are connected to pipes
within the said shell. Between the two outside pipes and the corresponding
internal pipes, provision is made for fitting the main and donkey feed check
valves.
The furnace flue is closed at the rear end, where the smoke tube is fitted, by
means of loose doors which may be lined with firebrick or the like, these doors
also supporting the back bridge. The furnace flue is swelled out at one end
so that it may be easily withdrawn in one piece and renewed. The combustion
chamber is closed at the end opposite to the fire tubes in the upper shell by
means of a suitable plate which may be lined with firebrick or the like, such

page_text: plate having a manhole with cover arranged in same so that an inspection of
the combustion chamber can be made with very little trouble. The upper shell
is or may be supported from the lower one by means of a strong saddle piece
in addition to the junction or neck-piece hereinbefore referred to. The end
plates of each shell are or may be strengthened by stays as usual, and a smoke
box is arranged at the front of the upper shell.
In another construction of boiler according to this invention, the tube plate
at the end of the upper shell opposite to the smoke box is set at an angle and
the upper shell is supported from the lower shell by means of vertical plates
running horizontally with the shells and firmly secured to the periphery of
each, the end cross plate at the smoke box end of the boiler forming a saddle
plate. Also the rear end of the upper shell of the boiler is kept short of the
lower shell and the vacant space thus provided is utiliséd to contain a com-
bustion chamber that is external to the upper shell and is connected to the
aforesaid vertical supporting plates and closes the partial box, which now, not
only supports the upper shell but forms a most efficient combustion chamber
and materially increases the heating surface of the boiler. The supporting
plates and combustion chamber plates may be lined with firebricks or the like
to retain the heat. A flanged vertical smoke tube is secured to the top of the
lower shell and to the top of the furnace flue so as to convey hot gases from
the latter to the combustion chamber.
Two flanged Galloway or like tubes secured to the lower part of the upper
shell and to the upper part of the lower shell form upcast circulating pipes,
the said tubes serving to tie the shells together, to assist in supporting the
upper shell, and forming a valuable heating surface. The arrangement of the
downcast pipe is similar to that in the construction of boiler first, herein
described.
Boilers according to my invention can be arranged for double ended firing.
which might in certain circumstances recommend itself. In one arrangement of
this kind a single lower shell arranged for double firing is combined with two
upper shells, the furnace flue being divided about midway of its length by
a transverse fire brick wall or division and the two combustion chambers being
external to the upper shells and separated from each other.
Boilers constructed according to this invention necessitate very few steam
and water space stays (and that only for very high pressures) and no combustion
chamber stays, whatever, and every part of the structure being circular and of
small diameter, the scantlings are necessarily light. Furthermore the formation
of the said boiler reduces the amount of dead water in the same to a minimum,
thus making it specially suitable for raising steam quickly. The heating surface
is most efficient, its arrangement being conducive to a thorough circulation of
the water, which thorough circulation ensures in its turn an even and gradual
expansion of every portion of the structure by reason of the temperature being
nearly equal at the extreme top and bottom. Finally the shape of this twin shell
boiler renders it specially suitable for fitting on board ships, since much less
waste space is left than is usually the case with the ordinary marine type of
boiler. Fitted side by side in groups, boilers according to this invention form
a compact mass, and, with a suitable arrangement of connections, each boiler
may be worked separately and independently from the others, or any boiler
can be shut off for cleaning or repairs, thus reducing the chances of a complete
breakdown in the stokehold to a minimum. The risk of leakage is exceedingly
small owing to the fact that the boiler has its shells in two plates with no cir-
cumferential seam, and the cost of production, owing to the small amount of
rivetting required, also compares favorably with that of any other class of
boiler. By reason of its comparatively small dimensions, a boiler according
to this invention can be disconnected, lifted on shore, repaired and replaced
without disturbing any part of the deck or fittings, except the cover plates on
the boiler casing hatch in the case of passenger or cargo steamers.
As compared

page_text: with many other forms of boilers, my improved boiler is less liable to get out
of order, every internal part being easy of access so that it can be cleaned and
examined and for this reason also the risk of explosions or accident is reduced,
as compared more especially with .many water tube boilers where the cleaning
and examination of the internal parts are difficult operations.
בד
OL
1
1000
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.
Improvements in and relating to Steam Dolers.
I, WILLIAM Scort, of Lyndhurst, 19, Plasturton Avenue, Cardiff, in the
County of Glamorgan, General Manager of the Tydvil Engineering and Ship
Repairing Company, do hereby declare ne 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:
-
This invention relates to the construction of high-pressure twin-shell boilers
especially adapted on account of their lightness, their good circulation, and
their rapid and constant production of steam, for shallow-draught steamers or
where weight is an important element, as in the case of such craft as cruisers
and fast passenger vessels, but adapted also for use on land.
Boilers according to this invention are constructed as will be described with
reference to the accompanying drawings, in which Fig. 1 is a longitudinal
section and Fig. 2 partly a cross section and partly an elevation of one example
of such a boiler, whilst Figs. 3 and 4, Figs. 5 and 6, and Figs. 7 and 8 are
respectively similar views of other examples.
Each of the boilers shown in Figs. 1 to 4 inclusive comprises two cylindrical
horizontal shells 1 and 2 placed vertically one above the other and connected
together by uptake and downtake connexions 3 and 4 respectively, the lower
shell 2 containing a furnace flue 5 that extends from end to end thereof and
the upper shell 1 containing horizontal fire tubes 6 that lead from one end
plate 7 of the upper shell to a combustion chamber 8 that is located at the
other end of the upper shell and is in communication with the furnace flue 5
by a vertical smoke tube 9.
In the example shown in Figs. 1 and 2, the combustion chamber 8 is of
circular section and located within the rear end of the upper shell 1 and is con-
nected to the rear end of the furnace flue by a vertical smoke tube 9 of circular
section. The upper end of the smoke tube is flanged for connexion to the lower
portion of the combustion chamber, and the lower end of the tube 9 is plain
and is secured to the top of the furnace tube 5, which is itself flanged upwards
to receive the same. At the points where the smoke tube 9 passes through
the upper portion of the lower shell and the lower portion of the upper shell 1
to connect the furnace tube 5 to the combustion chamber 8, a flanged junction
or neck-piece 3 is fitted and securely double riveted to both shells, the vertical
smoke tube 9 extending through the centre of the junction or neck-piece and
being surrounded by water. The junction or neck-piece 3, besides tying the two
shells together, forms the upcast connexion for heated water to pass from the
lower to the upper shell. A downcast connexion 4 is situated at the opposite
end of the lower portion of the upper shell at the smoke box end of the boiler

page_text: and comprises a T-piece 4 with two outside pipes that extend from the said
T-piece to the lower portion of the lower shell 2, where they are connected
to pipes 4b within the lower shell. The passage of hot gases through the upcast
connexion between the upper and lower shells, the down-cast connexion 4
between the lower portions of the upper and lower shells, and the position of
the furnace flue 5 in the lower shell cause the circulation of the water to be
so good that the expansion at the bottom of the boiler is very nearly equal to
that at the top, which is a very important advantage over smoke-tube boilers
of the marine type hitherto constructed, which have been very liable to acci-
dents resulting from varying expansion. Between the two outside pipes and
the corresponding internal pipes 4 there are fitted the main and donkey feed
check valves. The furnace flue 5 is closed at the rear end, where the smoke
tube 9 is fitted, by means of loose closures 10 which are fastened to the flue 5
by tap-bolts and which are lined with firebrick or the like and also support the
fire bars 11 at the back. The furnace flue is swelled out at one end, as shown
at 5", so that it can be easily withdrawn in one piece and a new one substituted
for it. The combustion chamber 8 is closed at the end opposite to the fire tubes
in the upper shell by means of a plate 8 which is lined with firebrick 8b or the
like and has a manhole S with a cover Sd, so that an inspection of the com-
bustion chamber can be made with very little trouble. The upper shell 1 is
supported by the lower one by means of a strong saddle piece 12 in addition to
the junction or neck-piece 3, the said saddle piece consisting of a middle
portion and two side portions connected by a bar 12ª. The end plates of each
shell are strengthened by stays 1 and 2ª as usual; for low pressures T-shaped
stays such as shown at 2b in Figs. 7 and 8 are sufficient. A smoke box 13 is
arranged at the front of the upper shell.
In the example shown in Figs. 3 and 4, the tube plate 14 at the end of the
upper shell opposite to the smoke box is set at an angle and the upper shell
is supported by the lower shell by means of vertical plates 15 running horizon-
tally with the shells and firmly secured to the periphery of each, whilst the
saddle piece 12 at the smoke box end of the boiler is connected to the plates 15
and the shells in an air-tight manner. The rear end of the upper shell 1 is
kept short of that of the lower shell 2 and the vacant space thus provided is
utilized to contain a combustion chamber 8 that is external to the upper shell
and whose wall 8° is connected to the vertical supporting plates 15 and closes
the partial box formed thereby, which consequently not only supports the upper
shell but forms a most efficient combustion chamber and materially increases
the heating surface of the boiler. In consequence of the arrangements described,
ample space for combustion is provided, without, as is sometimes the case, having
any portion of the combustion chamber at the rear of the lower shell, where it
would be liable to injury. The supporting plate 15 and other walls of the com-
bustion chamber are lined, as shown, with firebricks or the like to retain the
heat. A flanged vertical smoke tube 9 is secured to the top of the lower shell 2
and to the top of the furnace flue 5 so as to convey hot gases from the latter
to the combustion chamber S. Two flanged Galloway or like tubes 3 secured
to the lower part of the upper shell 1 and to the upper part of the lower shell,
form upcast circulating pipes and also tie the shells together, assist in supporting
the upper shell, and form a valuable heating surface; 3ª is a tube connecting
the extreme top of the lower shell with the bottom of the upper shell in order
to allow of the escape of steam into the upper shell from above the lower ends
of the tubes 3 in the lower shell. The downcast connexion and its appurtenances
are similar to those described with reference to Figs. 1 and 2.
Boilers according to my invention can be arranged for double-ended firing,
which might in certain circumstances recommend itself. Figs. 5 and 6 show an
example in which a single lower shell 2 arranged for double-ended firing is
combined with two upper shells 1; the furnace flue 5 is divided about midway
of its length by a transverse firebrick wall 16 supported by a casting 16ª adapted

page_text: to carry the grate bars; and the two combustion chambers 8, each of which
is provided with a manhole 8° in its side wall (the manhole might be in the
top of the combustion chamber), are external to the upper shells 1 and separated
from each other by a firebrick wall 17. The two combustion chambers are
connected by air-jacketed flues 18 with a common uptake 19. Each half of
the boiler is otherwise similar to the boiler shown in Figs. 3 and 4.
Figs. 7 and 8 represent a boiler similar to that shown in Figs. 1 and 2 but
illustrating some modifications. The combustion chamber 8 is made with a
flat top, which is strengthened by ordinary combustion-chamber girders 20,
whilst the sides of the combustion chamber are strengthened by ordinary screw
stays 21. By employing a combustion chamber with a flat top, a greater tube
surface and a considerably larger steam space can be obtained with an upper
shell of given size, than in the case of a combustion chamber of circular cross
section. The smoke tube 9 is provided with an Adamson flanged joint 9 to
make extra allowance for expansion, which might also be done by any other
suitable means, as a bowling hoop, which, however, is not as advisable as the
Adamson joint on account of the greater exposure of the rivets to the hot gases;
allowance for expansion may be similarly made in the smoke tubes of boilers
such as shown in Figs. 3 to 6. For the firebrick-lined closures employed in
the boiler shown in Figs. 1 and 2 at the rear end of the furnace flue 5 and
the rear end of the combustion chamber S, there are substituted iron castings 22,
23, 24, and 25 provided with plates 26, such castings and plates being perforated
as indicated, to allow a proper circulation of air. Similar castings and plates
may be used in lieu of brickwork-lined combustion-chamber walls in boilers
such as shown in Figs. 3 to 6, and in lieu of firebrick-lined furnace-flue closures
in boilers such as shown in Figs. 3 and 4.
Boilers constructed according to this invention necessitate very few steam and
water space stays (and that only for very high pressures) and no combustion
chamber stays whatever and every main part of the structure being circular and
of small diameter (except when the tops of the combustion chambers are flat),
the scantlings are necessarily light. Furthermore, the formation of such a
boiler reduces the amount of dead water in the same to a minimum, thus making
it specially suitable for raising steam quickly. The heating surface is most efficient,
its arrangement being conducive to a thorough circulation of the water, which insures
in its turn, an even and gradual expansion of every portion of the structure since it
causes the temperature to be nearly equal at the extreme top and the extreme
bottom. The shape of such a twin-shell boiler renders it specially suitable for
fitting on board ships, since much less waste space is left than is usually the case
with the ordinary marine type of boiler. Fitted side by side in groups, boilers
according to this invention form a compact mass, and, with a suitable arrange-
ment of connexions, each boiler may be worked separately and independently
from the other or others, or any boiler can be shut off for cleaning or repairs,
thus reducing the chances of a complete breakdown in the stokehole to a minimum.
The risk of leakage is exceedingly small owing to the fact that each shell is
formed by a single plate with no circumferential seam, except at the ends, and
the cost of production, owing to the small amount of riveting required, also
compares favorably with that of any other class of boilers. By reason of its
comparatively small dimensions, a boiler according to this invention (except when
made double as shown in Figs. 5 and 6) can be disconnected, lifted on shore,
repaired, and replaced without disturbing any part of the deck or fittings except
the cover plates on the boiler casing hatches in the case of passenger or cargo
steamers. As compared with many other forms of boilers, such a boiler is less
liable to get out of order, every internal part, including the interior of the or
each combustion chamber, being easy of access so that it can be cleaned and
examined, and for this reason also the risk of explosions and other accidents is
reduced, as compared more especially with many water-tube boilers, in which
the cleaning and the examination of the internal parts are difficult operations.

page_text: Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is: —
1. A steam boiler comprising two shells one above the other, a furnace flue
located in the lower shell, horizontal fire tubes connecting one end plate of the
upper shell with a combustion chamber at the other end thereof, a vertical smoke-
tube connecting the furnace flue with the combustion chamber and passing
through the upper portion of the interior of the lower shell, an upcast connexion
between the upper part of the lower shell and the lower part of the upper shell,
and an outside downcast connexion between the lower portion of the upper shell
and the lower portion of the lower shell, whether or not the smoke tube extends
through the upcast connexion, substantially as described.
2. Steam boilers constructed and arranged as hereinbefore described with
reference to and shown respectively in Figs. 1 and 2, in Figs. and 4, and
in Figs. 5 and 6 of the accompanying drawings, whether modified or not as
described with reference to and shown in Figs. 7 and 8 thereof.
Dated this 8th day of August 1900.
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.