IMPROVE- MENTS IN VERTICAL STEAM BOILERS
Year: 1874

page_text: LETTERS PATENT to Andrew Dunlop, of the City of Glasgow, in the
County of Lanark, North Britain, for the Invention of "IMPROVE-
MENTS IN VERTICAL STEAM BOILERS."
Sealed the 20th November 1874, and dated the 23rd September 1874.
PROVISIONAL SPECIFICATION left by the said Andrew Dunlop at
the Office of the Commissioners of Patents, with his Petition, on the
23rd September 1874.
I, ANDREW DUNLOP, of the City of Glasgow, in the County of Lanark,
5 North Britain, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN VERTICAL STEAM BOILERS," to be as follows:
-
The nature and novelty of this said Invention consist all as follows:-
The outer shell of the boiler is made of a usual cylindrical shape and with
a plain dome-shaped top. In the centre of the interior of this shell and at
the lower end is formed and placed a new or improved cone-shaped
heating chamber with its base nearly coinciding with the bottom of the

page_text: outer shell, and its highest part pointing to the centre of the dome to
which it is or may be attached by a tie rod or rods. Between this
central cone-shaped heating chamber and the outer shell a triangular or
conical annular shaped heating chamber or flue is formed, completely
surrounding the said central conical chamber, with its base in nearly the
same horizontal plane as that of and brought close or nearly so to the
bottom of the shell and central heating cone, and to which it is welded,
rivetted, or otherwise fixed at the base of the cone on one side and to
the outer shell on the other side, and with its ridge pointing upwards and
attached to the upper end of the boiler by stays or tie rods at several
places all round.
This new or improved mode of constructing heat chambers gives an
angular shaped water space all round between the outer shell and the
triangular shaped annular heat chamber or flue, and also a triangular
shaped water space all round between the said annular heat chamber
and the central conical heat chamber, and in some cases when desired
circulating water tubes might be inserted between these annular water
spaces across the lower part of the annular heating chamber. The firc
may be placed on bars a few inches above the bottom, either in the
central cone or in a part of the outer heat chamber. In the former case
which is preferred especially for smaller sized boilers, a firing tunnel or
mouth-piece is formed through all the outer spaces or chambers,
preferably at an angle downwards towards the grate surface for the
better feeding in of the fuel, and the waste products of combustion are
conveyed away through the bottom or the side near to the bottom of the
surrounding heat chamber or flue at any convenient part into the
chimney, and the said two heat chambers are connected to each other
by tubes placed about half way up and at the side of the boiler
diametrically opposite to that at which the waste products escape; or a
partition may be placed in any part of the triangular heat chamber, in
which case the tube or tubes from the central chamber would be made
to enter on one side of this partition and the waste products be allowed
to escape out at the other side of the partition after having circulated
all round the annular chamber, or nearly so, and when the fire is placed
at one side of the outer heat chamber the waste products are conveyed
away through the bottom of the central conical chamber, and the tubes
connecting the two heat chambers are placed at the side of the boiler

page_text: diametrically opposite to that at which the fire is placed; or a partition
may be placed at or near one side of the fire grating in the triangular
annular chamber, and the tube or tubes from it to the central chamber
would in that case be placed near to the partition at the other side of it
from that on which the fire is placed.
These new or improved boilers with conical, central, and triangular
shaped annular heat chambers give a large heating surface of metal
placed in an advantageous position for the heat to strike upon and for
the water converted into steam to rise from, thereby greatly promoting
the rapid production of steam and the economy of fuel, while at the
same time they are of a simple and durable construction and easily and
cheaply manufactured, giving great convenience of access for examination
and repair.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Andrew Dunlop in the Great Seal Patent Office
on the 22nd March 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDREW
DUNLOP, of the City of Glasgow, in the County of Lanark, North
Britain, send greeting...
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-third day of September, in the
year of our Lord One thousand eight hundred and seventy-four, in
the thirty-eighth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Andrew Dunlop, Her
special licence that I, the said Andrew Dunlop, my executors, admi-
nistrators, and assigns, or such others as I, the said Andrew Dunlop,
my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make,
usc, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN VERTICAL STEAM BOILERS," upon the condition (amongst
others) that I, the said Andrew Dunlop, my executors or administrators,

page_text: said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Scal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Andrew Dunlop, do hereby
declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement in writing, reference being had to
the accompanying Sheet of Drawings, and to the reference letters on the
Figures of the several modifications I have shown thereon, all for the
purpose of describing and illustrating the full nature of my said Inven-
tion and the best modes and means I am at present aware of for per-
forming or putting it into effect or practice, the same reference letters
indicating the same or like parts in all the Figures where shown:-
Figures 1 and 2 are respectively a sectional elevation (taken on the
line 11, in Figure 2) and a horizontal section (taken half on the lines
2- - -2, and 3- - -3, in Figure 1) of one modification of my said Invention or
general construction and arrangement of the parts of a vertical cylindrical
steam boiler A with an improved circular fire-grato B at the lower part
of a central conical heating chamber a connected by two flue tubes b
through the improved V shaped annular water space c (on each side of
the charging doorway D) into the A shaped annular heating flue or
chamber d, and leading off by the flue on the back opposite the
doorway D, C, to the chimney Z, all in accordance with the improve-
ments of or forming my said Invention, and illustrative of one modifi-
cation thoreof, all as will herein-after be more fully described, the red
arrows indicating the course of the flames and heated products of
combustion.
Figure 3 is an outside elevation of the fuel charging and fire cleaning
door C; and Figure 4 is a vertical section taken on the line 4---4 in
Figure 1 of the charging duct D within and closed by the door C, and of
the water space or duct D' surrounding it for protecting and preventing
it from being burned, and at the same time giving increased heating

page_text: surface and a perfect return circulation of the water from the lowest
and coldest part of the improved angular and annular water space e to
the hotter inner V shaped space c, all as indicated by the blue
arrows.
Figure 5 is a vertical section taken on the centre line 1---1, in Figure 6,
and Figure 6 is a horizontal section, one half taken on the line 2---2, and
the other on the line 3- - -3, in Figure 5, both of another modification of
my said Invention or improvements, more particularly suitable for and
shown as applied to a larger size of vertical steam boiler than that illus-
trated in Figures 1 and 2, and having an annular fire-grate B, in this
case formed in the lower part of the improved heating flue or chamber d
half round, with a charging and cleaning door and duct C, D, into each
quarter of the grate or fire B, but this grate B might be formed or
carried further or wholly round the annular flue d, and have three or
four doors C, D, formed and divided round the boiler to suit the grate so
formed. In this modification (Figures 5 and 6) three circular flue pipes
or ducts are fitted and led from the sides and back part of the hot fire-
chamber & through the annular V water space c into the central conical
heating chamber a, from the bottom of which in this case the waste
products of combustion after acting on and imparting their heat to the
various improved angled walls of the heating flues or chambers a, b,
and d pass off by the flue into the chimney Z. To give perfect cir-
culation to the water from the bottom of the outer annular space e to
the inner and hotter annular V shaped space c heated on two sides the
two tubular ducts c', c', are formed and jointed, preferably as shown in
the plan, Figure 6, and dotted in Figure 5, on opposite sides of the boiler
at the extreme end of and nearly all below the level of the grate B.
It will be understood however that these flues and water ducts and e¹
might be placed in other parts or positions and be more or less in
number according to their size and position.
Figures 7 and 8 are a vertical and a horizontal section respectively
taken on the corresponding lines 1---1, and 2---2, 3- - -3, in the opposite
Figures, all of a slightly different arrangement of the parts of a modifi-
cation of my Invention to that shown in Figures 1 and 2, with the fire
and grate B shown in the central heating space a suitable for a larger
boiler A, and therefore having this chamber a made larger and with less
angle, and with a larger domed part a' at the top to give greater heating

page_text: former Figures 1 to 6.
And referring to Figures 1 to 4, and Figures 7 and 8, the nature,
novelty, and mode of performing my said Invention consist all as
follows: The outer shell of the boiler A is made of a usual cylindrical
shape with any of the ordinary elliptical or spherical dome-shaped
tops A¹. In the centre of the interior of this shell and at the lower end
below the water line a new or improved cone-shaped heating chamber a
is formed and fitted with its base nearly coinciding with the bottom
at A of the outer shell A set on a suitable open basement of iron or
brickwork or other equivalent supports or pillars which would admit the
air to the fire, and with its highest part pointing to the centre of the
dome A¹ to which it is or may be attached by a tie rod or rods a".
Between this central cone-shaped heating chamber a and the outer shell
a triangular or conical A shaped annular heating chamber or flue dis
formed completely surrounding the said central conical chamber a with
its base d¹, d', in nearly the same horizontal plane as that of and brought
close or nearly so to the bottom A" of the shell A and the central
heating cone a, to both of which it is welded, rivetted, or otherwise fixed
in a usual manner at the base of the cone on one side d¹, and to the
outer shell on the other side d", and also at its ridge d², as in Figures 1
and 7, or with a curved annular top plate d, as in Figure 5, and
pointing upwards, and also attached to the upper end of the boiler by
stays or tic rods a¹¹ at several places all round.
This new or improved mode of constructing heat chambers or flues a
and d in vertical steam boilers gives an improved heating surface on
which the flames and hot gases act better than on vertical sided flues
and have an improved angular shaped water space e all round between
the outer shell A and the triangular shaped annular heat chamber or
flue d, and also an improved angular shaped water space c all round
between the said annular heat chamber d and the central conical heat
chamber a, preferably with circulating water ducts or tubes e¹ or D¹
inserted between these annular water spaces c and e across the lower
part of the annular heating chamber d. The fire is preferred to be
· placed on bars B a few inches above the bottom d¹, A", cither in the
central cone a or in a part of the outer heat chamber d, as in Figures 5

page_text: and 6. In the former case, which is preferred for smaller sized boilers,
a firing tunnel or mouth-piece D is formed through all the outer
spaces or chambers c, d, e, either horizontally, as shown in Figures 1
to 6, or at an angle downwards towards the grate surface for the better
feeding in of the fuel, as shown in Figures 7 and S.
The heated products of combustion in Figures 1 and 2 are conveyed
away from the central furnace chamber a through the two tubes 6 fitted
above and close to the feeding in and water ducts D, D', leading into
the heating chamber d so as to convey these products round in both
directions to the back or opposite side from which they are conveyed
through the flue below the boiler at A" into the chimney Z, but in
Figures 7 and 8 a brick division d³ is preferably formed in the heating
chamber d under and above the charging doorway and return duct D, D¹,
(but it might be placed at any other part of this chamber), and the con-
ducting flue from the fire-place or central heating chamber a is made
large and fitted close to one side of the brick division so that the heated
products in this case have to pass right round the annular heating
space before passing off through the bottom flue to the chimney Z
close to the other side of the brick division, all as indicated by the red
arrows in both modifications. When the fire is placed at one side of the
outer heat chamber d the waste products are conveyed away from the
bottom of the central conical chamber through a duct to the chimney Z,
and the tubes & connecting the two heat chambers a and d are preferably
placed at the sides of the boiler and nearly opposite to that at which the
fire is placed, all as shown, and indicated by the arrows in Figures 5
and 6; or otherwise in this modification a partition may be placed at or
near one side of the fire grating in the triangular annular chamber d,
and the tube or tubes b from it to the central chamber would in that
case be placed near to the partition at the other side of it from that on
which the fire is placed.
2
These new or improved boilers with conical, central, and triangular
shaped annular heat chambers give a large heating surface of metal
placed in an advantageous position for the heat to act upon and for the
water converted into steam to rise from in the V shaped annular water
spaces c and e, all as indicated by the blue arrows in the several Figures
13
1

page_text: and the economy of fuel, while at the same time they are of a simple
and durable construction and easily and cheaply manufactured, giving
great convenience of access for examination and repair.
These new or improved steam boilers have their furnace bars resting
on annular or segmental rings E fitted and supported on brackets E'
rivetted near the lower part of the heat chambers a and d, and the side
or sides of the annular flue space d may be stayed to the outside shell of
the boiler A by screw stays G rivetted at their ends, much in a usual
manner, or one side might be similarly stayed to the central cone a
across the water space c, although this is not shown in the Drawings,
and these boilers would also as usual be fitted with the ordinary man-
hole doors as A³, and with blow-off pipes and cocks preferably from
some convenient lower part of the annular water spaces e or c, and with
the other steam boiler mountings, such as the steam outlet and water
inlet branches or pipes and valves, floats, and gauges, although these
are not shown in the Drawings.
As described in reference to and shown in the several modifications
and Figures on the Sheet of Drawings it is preferred to use both the
conical, central, and the annular angled heating chamber combined, but
it is to be understood that a good boiler may be made in accordance
with this Invention with the annular angled heating chamber only, with
the inner sides of the A shaped annular space formed as an inverted
conc or truncated cone joined by a flat or domed piece and without the
_central, conical, heating chamber, and having the fire-grate in a sectional
or segmental portion of it, as shown in Figures 5 and 6.
Having thus described the nature of my said Invention, and the
manner of performing it, I would observe that I do not restrict myself
to the precise details or arrangements herein shown and described as
many variations may be made therefrom without departing from the
main or essential features of my said Invention, but what I consider
novel and original and therefore claim as the Invention secured to me
by the herein-before in part recited Letters Patent is,―
First. The constructing of steam boilers with a central, conical, or
truncated conical heating space, and an annular angled or A shaped
licating space combined, all substantially in the new or improved

page_text: manner and for the purposes herein-before described and shown in the
accompanying Drawings.
Second. The constructing of steam boilers with an annular and
angled or A shaped heating chamber only, substantially as herein-before
described.
In witness whereof, I, the said Andrew Dunlop, have hereunto
set my hand and scal, this Nineteenth day of March, in the
year of our Lord One thousand eight hundred and seventy-
five.
ANDREW DUNLOP. (L.S.)