An Improved Steam Boiler.
Year: 1891

page_text: Date of Application, 21st July, 1891.
Complete Specification Left, 26th Nov., 1891-Accepted, 2nd Jan., 1892
PROVISIONAL SPECIFICATION.
An Improved Steam Boiler.
I, ANDREW AUSTIN of Howard Street, Hartlepool, in the County of Durham,
Engineer, do hereby declare the nature of this invention to be as follows:-
My invention relates to boilers of the well known vertical type principally used
in steam ships and commonly called winch or donkey boilers in which a dome
shaped fire box of smaller diameter than the boiler shell occupies the lower part
of the boiler in combination with which various arrangements of cross tubes have
been employed to intercept and utilize as large a proportion as possible of the
heat from the fire box.
In order to obtain an advantageous distribution of heating surface these cross
tubes which extend over the crown of the fire box are so arranged at the smoke
box or front end that a large area of the boiler shell is cut away to accomodate
them by which the strength of the shell of the boiler as a cylindrical vessel is
materially affected.
The object of my invention is to arrange these cross tubes so that whilst proper
provision is made for an advantageous distribution of heating surface and for
accessibility to all internal parts of the boiler, the tubes are so arranged and
fixed in the shell of the boiler which retains its cylindrical form that the reduction
in strength of the shell due to the tube holes, shall not exceed the reduction in
strength caused by the rivet holes of a vertical scam of the same plate thus
dispensing with any necessity to increase the thickness of the shell plate through
which the tube holes pass at the front end. My improvements also enable the
usual cross stays to be dispensed with.
In carrying my invention into effect I arrange the cross tubes in two groups
the tubes in each group being parallel to each other, but each group of tubes
is set at an angle relatively to the tubes of the other group so that their lines of
direction intersect between the tube plates of the combustion chamber and the
shell of the boiler. The angle of intersection may be a right angle or other
convenient angle which affords a convenient space between the shell plate and
the two groups of tubes at the front end for access for cleaning and repairs. The
tube plate in the combustion chamber is set to at an angle corresponding to the
angle of intersection of the two groups of tubes, by which additional heating
surface is obtained in the proportion of two sides of a triangle to one. The tubes
in each group are conveniently arranged in rows say for instance seven tubes
arranged at one level form a row, these rows are taken in their vertical order from
each group alternately. By this arrangement the reduction in the vertical
sectional area of boiler shell taken through a series of tube holes is obviously
reduced to one half as compared with the reduction in sectional area if the same
number of tubes were all members of one group of parallel tubes and it will be
found in practice that the reduction of the sectional area of the boiler shell taken
vertically which is due to tube holes arranged according to my invention need not
exceed the reduction in the vertical section of the same boiler plate due to the
rivet holes of one of its vertical seams.
1
1001
G. J. CLARKSON,
Stockton-on-Tees, Agent for the Applicant.
G. J. CLARKSON,
Stockton-on-Tees, Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
An Improved Steam Boiler.
I, ANDREW AUSTIN, Engineer of Howard Street, Hartlepool, in the County of
Durham, do hereby declare the 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 :-
My invention relates to boilers of the well known vertical type principally used
in steam ships and commonly called winch or donkey boilers in which a dome
shaped fire box of smaller diameter than the boiler shell occupies the lower part of
the boiler in combination with which various arrangements of cross tubes have been
employed to intercept and utilize as large a proportion as possible of the heat from
the fire box.
In order to obtain an advantageous distribution of heating surface these cross
tubes which extend over the crown of the fire box are so arranged at the smoke box
or front end that a large area of the boiler shell is cut away to accomodate them
by which the strength of the shell of the boiler as a cylindrical vessel is materially
affected.
The improvements constituting my invention consist in arranging these cross
tubes so that whilst proper provision is made for an advantageous distribution of
heating surface and for accessibility to all internal parts of the boiler, the tubes are
so arranged and fixed in the shell of the boiler which retains its cylindrical form
that excessive reduction in strength of the boiler shell due to the tube holes may
be avoided and need not exceed the reduction in strength caused by the rivet holes
of a vertical seam of the same plate thus dispensing with any necessity to increase
the thickness of the shell plate through which the tube holes are cut at the
front end.
My improvements also enable the usual cross stays to be dispensed with.
In the drawing which forms part of this Specification two boilers are shown
differing from each other only in the construction of the combustion chamber
and the flues or communications leading from the fire box thereinto. Figures 2
and 4 are sectional views taken on line of Figures 1 and 3 respectively but it
will be observed that the boiler is shown in a different position in Figures 3 and 4
to the position shown in Figures 1 and 2, in order to bring out more clearly the
alternating position of the rows of cross tubes.
In the figures a is the fire box and is the combustion chamber, c and d are two
groups of cross tubes arranged according to my invention with the tubes of each
group parallel, but with each group set at an angle relatively to the other group, so
that their lines of direction intersect between the tube plates ff of the combustion
chamber and the shell of the boiler. The angle of intersection may be a right
angle as shown in the figures or other convenient angle which affords a convenient
space between the shell plate and the two groups of tubes at the front end e for
access for cleaning and repairs.
The tube plate ff in the combustion chamber 6 is set at an angle corresponding
to the angle of intersection of the two groups of tubes c and d by which additional
heating surface is obtained as compared with a single flue plate in the proportion of
two sides of a triangle to one. The tubes in each group are conveniently arranged
in rows say for instance seven tubes arranged at one level form a row, these rows
are taken in their vertical order from each group alternately that is to say referring
to Figures 1 and 3 which are alike in this respect a row of tubes d come above a
row of tubes c and then another row of tubes c above the said row of tubes d and so
on from row to row. By this arrangement the reduction in the vertical sectional
area of the boiler shell through a series of tube holes is obviously reduced to one
half as compared with the reduction in sectional area if the same number of tubes
were all members of one group of parallel tubes; and it will be found in practice

page_text: that the reduction of the sectional area of the boiler shell taken vertically which is
due to tube holes arranged as hereinbefore described need not exceed the reduction
in the vertical section of the same boiler plate due to the rivet holes of a vertical
seam.
Referring to the combustion chamber 6, although the particular formation of the
back plate g is not an essential feature of my invention and may be approximately
concentric with the boiler shell as shown in Figure 2; 1 prefer in some cases to
substitute for this the arrangement shown in Figure 4 in which the back plate g is
constructed on a duplex arrangement by converging to a joint at g².
An advantage of this arrangement is that increased heating surface is obtained at
the back of the combustion chamber, and the increased space e¹ is available for
access to that part of the boiler.
The combustion chamber is divided into two sections 6' 6' in consequence of this
formation of the back plate, which communicate with the fire box by means of
their respective flues h' and h³. The flanged flues or neck pieces as illustrated in
Figure 3 can also be used in cases where the combustion chamber is not divided
into sections in substitution of flanging the fire box crown plate to the back tube
plate as shown in Figure 1.
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 :-
:
--
Firstly In the construction of vertical boilers commonly called winch or
donkey boilers, the arrangement of cross tubes in combination with the form of
the combustion chamber by which two groups of cross tubes are set at an angle
relatively to each other, so that an excessive reduction of the sectional area of the
boiler shell through a series of tube holes taken vertically is avoided, substantially
as hereinbefore described with reference to the accompanying drawing.
Secondly-In vertical boilers commonly called winch or donkey boilers, the
general arrangement and construction of parts as described and illustrated with
reference to Figures 1 and 2 and to Figures 3 and 4 of the accompanying
drawing.
Dated this 25th day of November 1891.