IMPROVEMENTS IN STEAM BOILERS
Year: 1884

page_text: I, GRAHAM STEVENSON, of the Airdrie Engine Works, Airdrie, in the County of
Lanark, North Britain, Engineer, do hereby declare the nature of my said
invention for "IMPROVEMENTS IN STEAM BOILERS" to be as follows, that is to
say:
My said Invention has for its object to construct steam boilers with improved,
extended, and efficient beating surface, by combining and arranging parts so as to
be very durable, and extremely convenient of access for cleaning and repairs.
In carrying out my present Invention I adopt arrangements which are modifica-
tions or developments of the Invention described in the Specification of my Patent
N° 5907 of 1888 and I use large tubes which have the water inside of them and
which are to some extent like tubes described in the Provisional Specification
relative to my application for a Patent N° 10889 of 1884. These tubes are from
four to seven inches in diameter except.at the ends which are shaped like bottle
necks and are reduced to a diameter of from two to three inches.
The main body of the boiler is composed of two horizontal cylindrical shells
placed one above the other and a vertical cylindrical shell joined at its bottom to
the upper horizontal shell. The horizontal shells which are connected at numerous
points where they touch or nearly touch each other, are always full of water
whilst the vertical shell is partly filled with water, its upper part which is by
preference enlarged in diameter forming the steam space. The vertical shell may
be joined to the upper horizontal shell at one end or at the middle of the latter,
there being two furnaces or sets of furnaces in the former case and four in the
latter. These furnaces are arranged at the sides of the horizontal shells; and when
there are four furnaces or sets of furnaces one half are back to back with the
others and are stoked from the opposite ends. Rows of the tubes are connected to
the horizontal shells so as to extend laterally from them, those connected to the
lower shell being alightly inclined upwards and forming roofs to the furnaces,
whilst those connected to the upper shell are slightly inclined downwards and form
roofs for flues. The fire gases on leaving the several furnaces are united in a
combustion chamber or chambers near the bottom of the vertical shell, such
chamber or chambers being filled with chequered brickwork, and the fire gases are
there supplied with additional air, which is introduced in small jets between the

page_text: chequer spaces through which the gases pass but in opposite currents so that the
fire gases and air meeting, strike on and subdivide each other and thereby secure
complete intermixture and prevention of smoke On leaving the combustion
chamber the fire gases pass into flues formed with brick partitions between the
upper sides of the furnace roof tubes and the under sides of the upper or flue roof
tubes so that the gases may act on the largest possible amount of tube heating
surface. After traversing the flues formed above the furnaces, the fire gases pass
into flues formed around the vertical part of the main boiler these flues being
formed by similar tubes arranged horizontally or with some inclination in radial
positions round the vertical shell, their inner ends being fixed to the shell, by
preference, in the manner described in my carlier Provisional Specification berein-
before referred to whilst the outer ends are made to project through the outer
firebrick casing. The tubes are disposed helically round the vertical shell so as to
form a helical Blue passing round it as many times as its height will admit of; or
they may be arranged in an equivalent manner by disposing them so as to form a
series of annular spaces, openings being provided for the fire gases to pass into each
of such spaces in succession. In the vertical shell a hollow displacement vessel is
placed below the water level to reduce the quantity of water required to fill the
boiler up to the level, and to allow of steam being got up the more rapidly when
this is required. At the part where the tubes are attached to the vertical shell
they are arranged in twos vertically but they are slightly twisted or inclined so
that the two of each pair are side by side at their outer ends and in this way more
completely occupy the spaces which widen outwards in consequence of the radial
arrangement.
=
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In further explanation of the arrangement of the flue spaces it may be stated
that the rows of tubes projecting laterally from each side of the horizontal cylinders
forming the lower part of the boiler extend to an outer wall between which and
the cylinders the furnace space is contained. At the inner end of the furnace
space is the combustion chamber the lower row of tubes extending to it. The
space between the lower and upper rows of tubes forms, with the outer wall, a
flue space, which is divided by a longitudinal vertical brick partition stopping short
of the front end, so that the fire gases on leaving the combustion chamber proceed
towards the front end along the inner side of the partition, returning along its
outer side. The helical rows of tubes projecting from the vertical part of the
boiler combine with the outer vertical cylindrical wall to form helical flues up
through which the fire gases pass after passing through the other flue spaces above
referred to.
The arrangements hereinbefore described are suitable for a boiler of large power
and some of the parts may be reduced in size or omitted in boiler of comparatively
small size. Thus for example one of the horizontal,shells may be dispensed
with the tubes which cross over the furnaces being connected to the upper and
lower parts of the single horizontal cylindrical shell
The outer ends of the tubes which project through the wall or casing are
provided with removable caps which give convenient access for cleaning and which
are completely protected from any injurious action of the fire gases. By preferenc
these caps or covers are made duplex so that each is applied to two tubes putting
them in communication and facilitating circulation of the water. The дecks.o
the tubes have collars formed on them, or fixed on them by screwing or otherwise
and a clamping bar held on the two tubes by the collars has fixed in it a bolt which
passes through the cap piece; and the cap piece is secured when in position by
nut screwed on the outer end of this bolt. If preferred each cap may be arrange
to connect three or more tubes.
The series of tubes are extended so as to absorb as much as possible of the hea
of the fire gases so that the temperature of these gases may be reduced sufficient!
for them to be allowed to act without injury on the upper or steam space of th
central vessel or on tubes connected hereto. And the remaining heat of the fir

page_text: gases may be utilised by placing above the boiler a vessel of similar construction
with radiating tubes for the feed water to be passed through before entering the
boiler. As the abstraction of the heat from the fire gases in this way will
diminish the natural draught or ascensional power of the fire gases, a fan or blower
may be used either to force in or exhaust the air passing through the furnace and
flues. And the air thus passing through is by preference in part admitted at the
bridge or at any suitable part of the flues through a number of comparatively
small jet orifices directing the air against the current of gases with the view of
making it mix the more completely with them.

page_text: I, GRAHAM STEVENSON, of the Airdrie Engine Works, Airdrie, in the County of
Lanark, North Britain, Engineer, do hereby declare the nature of my said invention
for "IMPROVEMENTS IN STEAM BOILERS," and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement, that is to say
·
My said Ipvention has for its object to construct steam boilers with improved,
extended, and efficient heating surface, by combining and arranging parts so as to
be very durable, and extremely convenient of access for cleaning and repairs. In
carrying out my present Invention I adopt arrangements which are modifications
or developments of the Invention described in the Specification of my Patent
N° 5907 of 1883 and I use large tubes which have the water inside of them and
which are to some extent like tubes described in the Complete Specification relative
to my application for a Patent No 10689 of 1884. These tubes are from four to
seven inches in diameter except at the ends which are shaped like bottle necks and
are reduced to a diameter of from two to three inches..
The main body of the boiler is composed of two horizontal cylindrical shells
placed one above the other and a vertical cylindrical shell joined at its bottom to
the upper horizontal shell. The horizontal shells which are connected at numerous
points where they touch or nearly touch each other, are always full of water whilst
the vertical shell is partly filled with water, its upper part which is by preference
enlarged in diameter forming the steam space. The vertical shell may be joined to
the apper horizontal shell at one end or at the middle of the latter, there being two
furnaces or sets of furnaces in the former case and four in the latter. These
furnaces are arranged at the sides of the horizontal shell; and when there are four
furnaces or sets of furnaces one half are back to back with the others and are
stoked from the opposite ends. Rows of the tubes are connected to the horizontal
shells so as to extend laterally from them, those connected to the lower shell being
slightly inclined upwards and forming roofs to the furnaces, whilst those connected
to the upper shell are slightly inclined downwards and forin roofs for flues. The
fire gases on leaving the several furnaces are united in a combustion chamber or
chambers near the bottom of the vertical shell, such chamber or chambers being
filled with chequered brickwork, and the fire gases are there supplied with
additional air, which is introduced in small jets between the chequer spaces
through which the gases pass but in opposite currents so that the fire gases and air
meeting, strike on and subdivide each other and thereby secure complete inter-
mixture and prevention of smoke. On leaving the combustion chamber the fire
gases pass into flues formed with brick partitions between the upper sides of the
furnace roof tubes and the under sides of the upper or flue roof tubes so that the
gases may act on the largest possible amount of tube heating surface. After
traversing the flues formed above the furnaces, the fire gases pass into flues formed
around the vertical part of the main boiler these flues being formed by similar
tubes arranged horizontally or with some inclination in radial positions round the

page_text: vertical shell their inner ends being fixed to the shell, by preference in the manner
described in my earlier Specification N° 10689 of 1884 herein before referred to
whilst the outer ends are made to project through the outer firebrick casing. The
tubes are disposed helically round the vertical shell so as to form a helical flue
passing round it as many times as its height will admit of; or they may be
arranged in an equivalent manner by disposing them so as to form a series of
annular spaces, openings being provided for the fire gases to pass into each of such
spaces in succession. In the vertical shell a hollow displacement vessel.is placed
below the water level to reduce the quantity of water required to fill the boiler
up to the level, and to allow of steam being got up the more rapidly when this is
required. At the part where the tubes are attached to the vertical shell, they are
arranged in twos vertically but they are slightly twisted or inclined so that
the two of each pair are side by side at their outer ends and in this way more
completely occupy the spaces which widen outwards in consequence of the radial
arrangement.
A boiler made according to my Invention is shown.on the accompanying sheet
of explanatory drawings. Figure, 1, is a vertical section; figure, 2, a horizontal
section, and figures, 3, and 4, enlarged views of details; and in further explanation
of the arrangement of the flue spaces it may be stated that the rows of tubes, 6,
projecting laterally from each side of the horizontal cylinders, 7, forming the lower
part of the boiler extend to an outer wall, 8, between which and the cylinders, 7,
the furnace space is contained.. At the inner end of the furnace space, 9, is the
combustion chamber, 10, the lower row of tubes extending to it. The space
between the lower and upper rows of tubes, 6, forms, with the outer wall, a flue
space, 5, which is divided by a longitudinal vertical brick partition, 11, stopping.
short of the front end, so that the fire gases on leaving the combustion chamber
proceed towards the front end along the outer side of the partition, returning
along its inner side as indicated by the arrows in figure, 2. The helical rows of
tubes, 12, projecting from the vertical part of the boiler, 13, combine with the
outer vertical cylindrical wall, 14, to form helical flues up through which the fire
gases pass after passing through the other flue spaces above referred to. The
hollow displacement vessel hereinbefore referred to is shown by dotted lines, 23,
in figure, I.
The arrangements hereinbefore described are suitable for a boiler of large power,
and some of the parts may be reduced in size or omitted in boilers of com-
paratively small siza. Thus for example one of the horizontal shells, 7, may be
dispensed with the tubes, 6, which cross over the furnaces being connected to the
upper and lower parts of the single horizontal cylindrical shell.
The outer ends of the tubes, 6, and 12, which project through the wall or
casing, 8, or 14, are provided with removable caps, 15, as shown in figure, &, which
give convenient access for cleaning and which are completely protected from any
injurious action of the fire gases. By preference these caps or covers, 15, are made
duplex so that each is applied to two tubes putting them in communication and
facilitating circulation of the water. The necks, 16, of the tubes have collara, 17,
formed on them, or fixed on them by screwing or otherwise, and a clamping bar, 18,
held on the two tubes by the collars has fixed in it a bolt, 19, which passes through
the cap piece, 15, and the cap piece is secured when in position by a nut, 20, screwed
on the outer end of this bolt, 19. If preferred each cap may be arranged to connect
three or more tubes. These tubes are slightly twisted or inclined as shown in
figure, 4, so that the two of each pair are side by side at their outer-ends.
The series of tubes are extended so as to absorb as much as possible of the heat
of the fire gases so that the temperature of these gases may be reduced sufficiently
for them to be allowed to act without injury on the upper or steam space of
the central vessel, 13, or on tubes, 12, connected thereto. And the remaining heat
of the fire gases may be utilised by placing above the boiler a vessel, 21, of similar
construction with radiating tubes, 22, for the feed water to be passed through before

page_text: entering the boiler. As the abstraction of the heat from the fire gases in this way
will diminish the natural draught or ascensional power of the fire gases, a fan or
blower may be used either to force in or exhaust the air passing through the
furnace and flues. And the air thus passing through is by preference in part
admitted at the bridge or at any suitable part of the flues through a number of
comparatively small jet orifices (as for example by pipes, 24,) directing the air
against the current of gases with the view of making it mix the more completely
with them.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is
"
The arranging or combining together of the parts of steam boilers in the improved
manner substantially as hereinbefore described.