Improvements in Steam Boilers.
Year: 1891

page_text: Date of Application, 24th Nov., 1891
Complete Specification Left, 24th Aug., 1892-Accepted, 24th Sept., 1892
PROVISIONAL SPECIFICATUN.
Improvements in Steam Boilers.
We DAVID DAVY, Engineer, and DAVY BROS. LIMITED, Engineers, both
of Park Iron Works Sheffield in the County of York, do hereby declare the nature
of this invention to be as follows:-
Our invention relates to improvements in the construction of steam boilers
having an internal flue with transverse water tubes fixed therein and it has for its
objects to obtain a better circulation of the water in the boiler a more efficient
heating surface, greater durability of the water tubes and facility for inspection
cleaning and repairs not only within the flue but within the boiler above beneath
and around the flue and within the water tubes.
The invention is applied preferably though not necessarily to internally flued
boilers of that type having two separate circular fire boxes merging into a single
flue of a breadth about equal to that of the two fire boxes, and of a corresponding
height, and the invention consists in fixing in said flue a single central row of
vertical tubes communicating with the water space above and below the flue and
of such diameter as to admit of a man passing through them for the purpose
of examining, cleaning, and repairing the tubes or any part of the boiler above or
below the flue. These pipes being of such large diameter permit of a very free and
rapid circulation of the water through them, the friction of the water against their
sides being proportionately less and they are not liable to fur up as are tubes
of small diameter and being in a single central row the flames in passing through
the flue are caused, either by the water tubes alone, or by the aid of fire brick
baffles within the flue, to take a zig-zag or wave-like motion and to impinge
directly against the sides of the tubes which are consequently heated more rapidly
than the sides of the flue over which the flames merely glide and in consequence of
this difference of efficiency of the heating surface a vigorous circulation of the
water is maintained, the water ascending from the bottom of the boiler through the
tubes and descending between the sides of the flue and the shell of the boiler,
thereby promoting a uniform heating of the water in the boiler and avoiding the
evil effects consequent on defective circulation.
The flue is of oblong form in cross section with rounded sides and either flat at
top and bottom or upwardly arched both at top and bottom to afford more room for
inspection cleaning and repairs beneath the flic. It is made in lengths connected
by joints preferably but not necessarily of the Adamson type alternating with and
in close proximity to the water tubes so as in conjunction with the latter to afford
adequate strength to resist collapse of the flue. The water tubes may be either
rivetted or welded into the top and bottom of the flue and may either be parallel or
preferably slightly tapered to facilitate manufacture when welded in.
Dated this 24th day of November 1891.
D. DAVY,
DAVY BROS., LIMITED,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.

page_text: COMPLETE SPECIFICATION.
Improvements in Steam Boilers.
We DAVID DAVY, Engineer, and DAVY BROS. LIMITED, Engineers, both
of Park Iron Works, Sheffield, in the County of York, 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:—
Our invention relates to improvements in the construction of steam boilers having
an internal flue with transverse water tubes fixed therein, and it has for its objects
to obtain a better circulation of the water in the boiler, a more efficient heating
surface, greater durability of the water tubes and facility for inspection cleaning
and repairs not only within the flues but within the boiler above, beneath and around
the flue and within the water tubes.
Reference is to be had to the accompanying drawings forming a part of this
Specification wherein
Figure 1 is a longitudinal section (taken on line 1-1 Figure 2) of an internally
flued boiler provided with a single central row of vertical water tubes in accordance
with my invention, one of the tubes being represented as rivetted and the others
as welded to the corresponding sections of the Hue.
Figure 2 is a horizontal section of the same.
Figure 3 is a cross-section of the boiler shewing the flue as flat at top and
bottom, and
Figure 4 is a similar section shewing the flue arched at top and bottom; either
mode of fixing the water tubes being applicable to either form of flue, as hereafter
described.
The same letters of reference indicate the same parts in all the figures.
The invention is applied preferably, though not necessarily, to internally flued
boilers having two separate circular fire boxes A A, merging into a single flue B of
a breadth about equal to that of the two fire boxes and the intervening space and
of a height corresponding to that of the fire boxes, all as represented in the
drawings.
The invention consists in fixing in said flue B a single central row of vertical
water tubes CC communicating with the water space above and below the flue,
said tubes being of such diameter as as to admit of a man passing through them
for the purpose of examining, cleaning, and repairing the tubes or any part of the
boiler above or below the flue. These tubes being of such large diameter the
friction of the water against their sides is proportionately diminished and they
consequently permit of a very free and rapid circulation of the water through
them and they are not liable to fur up as are tubes of small diameter. The
tubes C being in a single central row, the flames in passing through the flue are
caused either by the water tubes alone or with the aid of fire brick baffles D,
situated within the flue opposite the spaces between the tubes-to follow a zig-zag
or wave like course and to impinge directly against the sides of the tubes C which
are consequently heated more rapidly than the sides of the flue B over which the
flames merely glide. In consequence of this difference of efficiency of the heating
surfaces a vigorous circulation of the water is maintained, the water ascending
from the bottom of the boiler through the tubes and descending between the sides
of the 'flue and the shell of the boiler, as indicated by the arrows, thereby promoting
a uniform heating of the water in the boiler and avoiding the evil effects consequent
on defective circulation: The flue B is of oblong form in cross-section with rounded
sides corresponding preferably in curvature to the outer semi-circumferences of the
two fire boxes A. A, and either flat at top and bottom, as represented in Figure 3,
or upwardly arched both at top and bottom, as in Figure 4, to afford more room
for inspection, cleaning, and repairs, beneath the flue. The flue B is made in
lengths or sections connected by joints (preferably, but not necessarily, of the

page_text: Adamson type) alternating with and in close proximity to the water tubes C so as
in conjunction with the latter to afford adequate strength to resist collapse of
the flue. The water tubes may be either rivetted or welded into the top and
bottom of the flue and may either be parallel or, preferably, slightly tapered
to facilitate manufacture when welded in. An example of a rivetted tube is shewn
at C in Figures 1 and 2 in which the tube has flanges c c at top and bottom and is
of a length to fit within its section of the flue B the apertures in which approxi-
mately correspond to the bore of the water tube whose flanges are rivetted to
the top and bottom of the flue, as shewn. The tubes C are represented as being
welded into the top and bottom of the flue. In this case they would also be
flanged but of a length corresponding to the external height of the flue, the flanges
overlapping the edges of the apertures in the flue sufficiently to make good welded
joints; either mode of fixing water tubes is applicable both to the flat and arched
form of flue, the flanged ends of the tube being shaped to correspond.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is-
The construction of an internally flued boiler with a single central row of
vertical water tubes of large diameter, each rivetted or welded to the flat or
arched top and bottom sides, of a separate section of a flue whose joints alternate
with and are in close proximity to the water tubes, substantially as and for
the purposes specified.
Dated this 24th dose of Anos 1900
D. DAVY,
DAVY BROS., LIMITED,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.