IMPROVEMENTS IN STEAM GENERATORS STEAM GENERATORS
Year: 1873

page_text: LETTERS PATENT to John Davey, of Wisbeach, in the County of
Cambridge, Engineer, for the Invention of "IMPROVEMENTS IN STEAM
GENERATORS."
PROVISIONAL SPECIFICATION left by the said John Davey at the
Office of the Commissioners of Patents, with his Petition, on the
9th April 1878.
I, JOHN DAVEY, of Wisbeach, in the County of Cambridge,
Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN STEAM GENERATORS," to be as follows:―
My Invention of improvements in steam generators has for its object
to cause a rapid circulation of the water, so that the heat evolved from
the fuel may be more completely taken up and a consequent economy
of fuel effected.
The Inuention han

page_text: engines. To this end I prefer to construct the boiler of an annular form
having the fire-place and hot air chamber in the centre, and therefore
surrounded by a water space connected with which are sets or bent
water tubes which project into the hot air chamber, so that the heated
gases may pass between them and yield a considerable portion of the 5
caloric to the water that circulates through the tubes.
In the annular water space which surrounds the fire-box there is
a metal cylinder which subdivides this space into two annular spaces
which of course are concentric. This metal cylinder or partition does
not reach to the bottom of the water space so that there is a passage 1
beneath it which as it is extended down below the level of the fire-bars
forms a mud space. At the upper end of the cylinder there is an
inclined flange which projects over the inner annular water chamber.
ends
The water tubes above mentioned communicate at their
upper
with the inner annular water space; but their lower ends are carried across ]
this latter and open into the outer annular water space, the consequence
is that the water will flow down the outer annular space, and part of it
will pass under the cylindrical partition to the inner annular space, up
which it will ascend, and part of the water will enter the lower open
ends of the water tubes, and on rising therein will be discharged into :
the upper part of the inner annular space when it will be deflected
towards the central chimney or flue, and from thence after getting rid
of the steam it will pass back over the top of the flange to the upper
part of the outer annular space, down which it will again pass with the
fresh water. In this way a continued and rapid circulation of the water:
will be kept up in the boiler, and the steam evolved will pass to the
upper part where it will still further heat by being brought in contact
with the heated sides of the central flue or chimney.
In adapting the Invention to locomotive engines the water spaces
surrounding the smoke box and fire chamber are divided by vertical
arch shaped partitions into two parts which constitute vertical passages
that communicate with each other both at top and bottom, so that the
cooler water passes down one passage and up the other, and thereby a
rapid and constant circulation of the water in the boiler is maintained.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Davey in the Great Seal Patent Office on
the 9th October 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
DAVEY, of Wisbeach, in the County of Cambridge, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Ninth day of April, in the year of
our Lord One thousand eight hundred and seventy-three, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Davey, Her special licence that
I, the said John Davey, my executors, administrators, and assigns, or
such others as I, the said John Davey, 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, 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 GENERATORS,"
upon the condition (amongst others) that I, the said John Davey, my
executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, 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 I, the said John Davey, 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, reference being had to the Drawing hereunto
annexed, and to the letters and figures marked thereon (that is to
say) :—

page_text: a
The Invention is applicable under suitable modifications to stationary,
locomotive, and marine engines.
' In the accompanying Drawing Fig. 1 shows a stationary boiler in
vertical section constructed according to my Invention, and Fig. 2 is a
sectional plan of the same. This boiler is cylindrical, its main water
space A, A, being of an annular form and having its fire-place and hot
air chamber B in the centre. Connected with the annular water
space A are sets of bent water tubes O which project into the hot air
chamber, so that the heated gases may pass between them and yield
a considerable portion of the caloric to the water that circulates :
through the tubes. In the water space A which surrounds the fire-box
a metal cylinder D is inserted. This cylinder is made of such diameter
that it will subdivide this space into two annular spaces which of course
are concentric. This cylindrical partition D reaches to near the bottom
of the water space, and it is held in place by means of radial screw bolts
passed through the skin of the boiler, and forming stay bolts for the
walls of the water space A. Below and above the cylinder D the water
is free to pass to one side or the other, as shewn by the arrow in Fig. 1.
At its upper end the cylinder is formed with a flange which projects
over the inner annular water chamber. The water tubes C, C, com-
municate at their upper ends with the inner division of the water
space A; but their lower ends extend to the cylindrical partition D and
open into the outer division of the water space; the consequence of this
arrangement is that the tendency of the water in the upper part of the
boiler will be to flow down on the outside of the cylinder D, and pass
either under the cylindrical partition and flow upwards over the wall of
the fire-chamber acquiring increased heat in its progress or it will enter
the lower open ends of the water tubes C, and on rising therein discharge
into the upper part of the boiler near the central chimney or flue E
where it will get rid of its steam and will pass back over the flange of
the cylindrical portion to the outer division of the annular space, down
which it will again pass, mingling with the fresh water supply. In this
way a continued and rapid circulation of the water will be kept up in
the boiler, and the steam evolved will pass to the steam chamber where
it will acquire still further heat by being brought in contact with the
heated sides of the central flue or chimney E. The water tubes O it
will be seen by reference to Fig. 2 are arranged radially, and to facilitate
the circulation of the flame and gases around them a deflector F is

page_text: provided which is placed immediately below the opening to the central
chimney E.
Figures 3 and 4 shew in longitudinal sectional elevation, and in
sectional plan a slightly modified form of the above described cylindrical
boiler. This is intended chiefly for marine purposes. This boiler differs
somewhat in its proportions from that shewn at Fig. 1, the height being
somewhat less and the diameter greater, but the chief difference consists
in its having three sets of water tubes 0, 0, 0³, the tubes O¹ being
arranged intermediate of the tubes C, O³. I prefer when employing
these radially arranged tubes slightly to contract their upper ends as
indicated at c, Fig. 8, and thereby to provide a check to the discharge
of the water, and prevent the blowing out of the water and the emptying
of the tubes. The letters of reference in Figures 3 and 4 being the same
as those used in Figures 1 and 2, and the action of the two boilers being
substantially the same, no further description of this modification will be
required.
Figures 5 and 6 represent my improvements for ensuring a rapid
circulation of water in boilers as applied to a locomotive boiler;
Fig. 5 being a partial longitudinal section, and Fig. 6 a transverse
section of the same taken in the line 1, 2, of Fig. 6. A, A, is the water
space surrounding the rectangular fire-chamber B. This water space is
divided vertically throughout the greater portion of its depth by
plates 0, 0, 0, which extend upwards at the front and sides a little
above the top of the fire chamber, where they bend over inwards for the
purpose of deflecting inwards the ascending ourrent of water. The
plate O at the back of the fire chamber extends upwards in a segment
shaped form following the curve and being nearly coincident with the
barrel D of the boiler; E, E, are the fire-tubes extending from the fire
chamber B to the smoke box F, as usual. In the centre of this group of
tubes I insert two vertical division plates G, G, which extend down to
near the barrel D of the boiler, and have flanges at their upper ends
tending in opposite directions to the flanges of the division plates C.
These plates G extend from one tube plate to the other and are secured
thereto by angle iron connections. The office of these plates G is to
ensure a downward flow of the water in the barrel of the boiler, which
water is then free to circulate upwards between the fire-tubes and carry
off the heat therefrom. The division plates O will perform precisely the
same duty for the rectangular water space as will the cylinder D, for the

page_text: annular water space in the stationary marine boilers already described.
The division plates O will be held in position by the stay bolts used in
the construction of the boiler.
Having now set forth the nature of my Invention of "Improvements
in Steam Generators," and explained the manner of carrying the same 5
into effect, I wish it to be understood that under the above in part
recited Letters Patent, I claim ensuring a regular flow or circulation of
water through the water spaces of steam boilers by applying to the
water tubes and water spaces partitions or dividing plates constructed
and arranged as above described.
In witness whereof, I, the said John Davey have hereunto set
my hand and seal, the Eighth day of October, in the year
of our Lord One thousand eight hundred and seventy-three.
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