IMPROVEMENTS IN STEAM BOILERS
Year: 1853

page_text: LETTERS PATENT to George Duncan, of Chelsea, in the County of
Middlesex, Engineer, for the Invention of "IMPROVEMENTS IN
STEAM BOILERS."
Scaled the 27th August 1853, and dated the 28th February 1858.
PROVISIONAL SPECIFICATION left by the said George Duncan at
the Office of the Commissioners of Patents, with his Petition, on
the 28th February 1853.
I, GEORGE DUNCAN, of Chelsea, in the County of Middlesex, En-
gineer, do hereby declare the nature of the said Invention for "Im-
PROVEMENTS IN STEAM BOILERS" to be as follows:-
This Invention relates to a peculiar arrangement of tubular boiler, so
contrived as to obtain a very large and effective heating and evaporative
surface within very little space, and in economy in fuel, whilst a dimi-
nished quantity of water is required in the boiler.
It consists, under one modification, of a horizontal tubular shaft,
the end of which opens into a concave disc, bolted up to a disc tube
plate, so as to form a close chamber. From the opposite side of this
disc plate a cylindrical collection of open-ended tubes passes to

page_text: similar disc chamber at their opposite end, the latter chamber being
similarly carried on a tubular shaft end, the whole being in one hori-
zontal axial line. This forms the entire boiler. It is set over a
suitable fire enclosed in a furnace, and is inade to revolve at a slow
rate on its horizontal axis, so as to expose each increment of the
periphery of the collection of tubes gradually and successively to the
action of the fire. The water level in the boiler is set at some distance
below the level of the horizontal axis; and as the boiler revolves the
fluid pours out of the ascending tubes into the two end chambers, and
thence continually finds its way into the bottom tubes for the time
being where the greatest fire heat is. By this contrivance the water
is continually exposed to the fire in small quantities, and is easily
evaporated at a comparatively low temperature, the feed water being
supplied as required through one tubular shaft, whilst the steam passes
off by the other. Various forms of end chambers may be used, and the
tubes may be arranged together in many ways; the essential object
of the improvements being the obtainment of an efficient evaporative
power by means of a large area of tube surface traversing over a furnace,
or in contact with a suitable heating medium.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said George Duncan, in the Great Seal Patent Office,
on the 27th August 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
GEORGE DUNCAN, of Chelsea, in the County of Middlesex, Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of February, in the
year of our Lord One thousand eight hundred and fifty-three, in the
sixteenth year of Iler reign, did, for Herself, Ier heirs and successors,
give and grant unto me, the said George Duncan, Her special licence
that I, the said George Duncan, my executors, administrators, and
assigns, or such others as 1, the said George Dunean, my executors,
administrators, and assigns, should at any time agree with, and no

page_text: others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
STEAM BOILERS," upon the condition (amongst others) that I, the said
George Duncan, by an instrument in writing under my hand and seal,
should particularly describe and ascertain the nature of the said In-
vention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that 1, the said George Duncan, do hereby de-
clare 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, reference being had to the accompanying
drawings, and to the letters and figures marked thereon, that is to
say:
My said Invention relates to a peculiar arrangement of tubular
steam boiler, so contrived as to obtain a very large and effective heating
and evaporative surface within very little space, and capable of working
with great economy in fuel, whilst a diminished quantity of water is
required in the boiler. It consists, under one modification, of a hori-
zontal tubular shaft, the end of which opens into a concave disc, bolted
up to a disc tube plate, so as to form a close chamber. From the
opposite side of this disc plate a cylindrical collection of open-ended
tubes passes to a similar disc chamber at their opposite end, the latter
chamber being similarly carried on a tubular shaft end, the whole
being in one horizontal axial line. This forms the entire boiler. It is set
over a suitable fire enclosed in a furnace, and is made to revolve at a
slow rate on its horizontal axis, so as to expose each increment of the
periphery of the collection of tubes gradually and successively to the
action of the fire. The water level in the boiler is set at some distance
below the level of the horizontal axis; and, as the boiler revolves, the
fluid pours out of the ascending tubes into the two end chambers, and
thence continually finds its way into the bottom tubes for the time

page_text: being where the greatest fire heat is. By this contrivance the water
is continually exposed to the fire in small quantities, and is easily
evaporated at a comparatively low temperature, the feed water being
supplied as required through one tubular shaft, whilst the steam passes
off by the other. Various forms of end chambers may be used, and
the tubes may be arranged together in many ways, the essential object
of the improvements being the obtainment of an efficient evaporative
power by means of a large area of tube surface traversing over a
furnace, or in contact with a suitable heating medium. Figure 1,
on my Sheet of Drawings, is a longitudinal section of the boiler, as
letached from its supporting bearings, and from its connecting steam
pipe; Figure 2, is an external face elevation of one of the end discs
of the tubular chamber, detached; and Figure 3, is a similar end view
of one of the internal tube plates, showing the series of tubes and the
central or concentric cylinder in transverse section. The whole boiler
is supported on the two end tubular journal pieces or shafts A, which
are carried in suitable bearings at the parts B. The inner open end
of each of these shafts is bolted up against the centre of the concave
disc C, and on the outside or convex surface of such disc; the thorough-
fare through the shaft being set directly opposite to the aperture D, in
the centre of the disc. These two discs, with their concave sides
towards cach other, are set just so far asunder as the length of the
tubular chamber of the boiler may require. This intermediate tubular
chamber is composed of the two flat-end discs or tube plates E, each
having a large hole F, in its centre, and the two being connected
together transversely by a central tubular chamber or shell G, of boiler
plate riveted at each end to the plates E; the thoroughfare through
the tube G, being coincident with the holes F, in the discs. The two
discs or plates are further secured together by the cross tension rods H.
In the present example, each plate E, is pierced with two rings of tube
holes, as more especially pointed out in Figure 3, on my Drawings; and
open-ended tubes I, in correspondence with these holes, are secured into
and between the two disc plates, in the ordinary manner of tubing
boilers. Thus arranged, the steam generator is placed horizontally
over a suitable fire, in such a manner that the heat therefrom may

page_text: gene-
circulate up and between the tubes, the whole apparatus being caused
to revolve slowly upon its journals B. And to admit of this revolution
without interfering with the steam and water connexions of the
rator, a stuffing box J, is fitted to each projecting end of the tubular
shafts. To the stuffing box on one side is attached a copper steam
pipe K, for conveying away the generated steam for use as required,
whilst a similar pipe may be attached at the opposite end L, for the
introduction of the water. This may be effected by passing a stationary
water-supply pipe through the tubular shaft, such pipe being bent
downwards, and entered laterally into the water space, between the
flat tube plate and its corresponding concave disc.
In this way a
regular water supply may be kept up without interfering with the other
functions of the apparatus, the tubular shaft A, being made to work
steam-tight over the internal water-supply pipe by a stuffing box or
ground joint. It will thus bo obvious that the lower portions of the
two end disc spaces, and the bottom tubes I, for the time being, are the
water spaces in the boiler; whilst the upper portions of the disc spaces,
the upper tubes for the time being, and the central shell or tubular
picce G, are the steam spaces. Externally, the heating medium acts
upon the outside surfaces of the whole of the tubes I, as well as upon
the tube G, in the centre and the end discs. The generated steam
may, of course, be drawn off at each tubular shaft, if necessary. Cel-
lular chambers may also be used instead of the tubes I, as heating
surfaces. Or a plain boiler, with or without flues, may be used as the
steam generator.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used
or carried into effect, I would observe, in conclusion, that I do not
confine or restrict myself to the precise details or arrangements which
I have had occasion to describe or refer to, as many variations may be
made therefrom without deviating from the principles or main features
of my Invention; but what I consider to be novel, and therefore claim
as the Invention secured to me by the herein-before in part recited
Letters Patent, is,―
First, the general arrangement and construction of steam boilers, as
herein-before described.

page_text: Second, the system or mode of generating steam by means of tubular
or cellular chambers revolving or moving over a furnace or heating
medium.
Third, the application and use of a tubular or cellular steam gene-
rator, or a plain boiler, with or without flues, for generating steam by
revolving or moving over a fire or heating medium.
In witness whereof, I, the said George Duncan, have hereunto set
my hand and seal, the Twenty-fourth day of August, One
thousand eight hundred and fifty-three.
GEORGE DUNCAN.
(L.8.)