IMPROVEMENTS IN STEAM BOILERS
Year: 1883

page_text: Com-
PROVISIONAL SPECIFICATION left by Alexander Melville Clark at the
Office of the Commissioners of Patents on the 29th January 1883.
municated to him from abroad by Edouard Delpech, of Marseilles France.
ALEXANDER MELVILLE CLARK of the firm of A. M. and W. Clark of 53 Chancery
Lane in the County of Middlesex Fellow of the Institute of Patent Agents
"IMPROVEMENTS IN STEAM BOILERS." [Communicated to him from abroad by
Edouard Delpech, of Marseilles France]
This Invention relates to improvements in marine and land stationary tubular
steam boilers, of which one of the essential features is the employment of double
return flame tubes whether the boiler has a single or double shell or barrel.
In order that the Invention may be more readily understood, I have illustrated
examples thereof in the annexed drawings, in which Figure 1 is a longitudinal
vertical section on line GH Figure 4, of a marine boiler. Figure 2 is an end
elevation, Figure 3 is a transverse section on line M N Figure 4, and Figure 4 is a
horizontal section on line I J K L Figure 1 of the same. Figure 5 is a front
elevation of a land stationary boiler having double return flame tubes. Figure 6 is
a transverse section of the same on line A B Figure 7 which is a longitudinal vertical
section through the brick work setting.
In Figures 1. 2. 3 and 4, A are the hand hole doors for removing deposits in the
boiler. B soot doors. Cash pit doors. D is a water bridge connecting the two
side water walls of the water casing. E water column connecting the two barrels
of the boiler to the bottom of the water casing. F side openings connecting the
two barrels with the water casing.
The novel construction and arrangements herein described and represented in the
drawings enable a considerable economy of fuel to be effected when flaming coal is
used, and moreover have the advantage of preventing the overheating of the barrel
of the boiler as the flames from the furnace do not strike directly against it.
The double marine boiler with double return flame tubes represented in
Figures 1. 2. 3. 4. is constructed of two main tubular boiler shells or barrels each
having four heaters beneath and connected to them as shown. These heaters are
the first to receive the direct action of the heat from the furnaces. This arrange-
ment of the heaters whilst enabling the generation of large quantities of steam has
the advantage of completely protecting the main shell of each boiler from over-
heating, and in case of the overheating of one of the heaters, it may be easily
replaced at sea by carrying spare heaters, it being evident from the mode of
construction represented in the drawings that this can be done without difficulty.
The two barrels are set in a furnace contained within a water casing suitably
stayed and communicating with the main barrels so as to constitute a part of the
water space of the boiler. A horizontal water bridge D connects the side walls of

page_text: the water casing and occupies the vacant space between the two barrels between
the upper and lower sets of tubes. The two barrels are connected at the lower
part by a branched tube E with the bottom of the water casing which extends
entirely beneath the furnaces and are likewise in communication by apertures F at
the sides with the upper part of the side walls of the water casing to ensure a
proper circulation throughout the boiler and the free passage from the water casing
of the steam generated therein. A brickwork division is placed between the two
sets of furnaces to prevent eddying of the flames and cause them to pass straight to
the point where they are distributed respectively to the lower set of flame tubes in
each barrel.
The ends of the boilers are lined with brickwork which surrounds the fire door
openings, prevents the radiation of heat to the stoke hole, and intercepts direct
communication between the furnaces and the end uptakes where the gases pass
from the lower to the upper set of flame tubes, except through small ducts or flues
made in the brickwork for the purpose of reigniting the gases of combustion which
have been extinguished by passing through the first set of return tubes whereby a
perfect utilization of the heating power of the fuel is effected. These ducts or
flues are an essential feature of the Invention and are also applicable to land
boilers.
Marine boilers may have a single or double barrel but in all cases have a double
return of the flames as before explained the difference between the double and
single type being the omission of the water bridge.
In the case of double land stationary boilers represented in Figures 5, 6 and 7
I obtain the same economy of fuel especially with long-flaming coal, and I also
obtain the advantage of avoiding overheating the barrel of the boiler, by reason of
the position of the two furnaces placed laterally beneath the boiler shell the flames
do not strike vertically upwards against the boiler but play tangentially around
the sides.
The brickwork in which the double boiler is set forms a chamber so constructed
as to partially embrace the two shells as indicated by dotted lines in Figure 6 so
as to form flues which convey the flames uniformly over their whole external
surface up to their rear end. At this point the flames enter the tubes of the upper
shell or barrel return therethrough to the front, descend and enter the tubes of
the lower barrel through which they pass to the chimney.
This double return of the flames ensures the complete utilization of the whole of
the heating power of the fuel. The lower barrel is provided with a cylindrical
prolongation constructed of boiler plate and projecting through the front of the
boiler setting and provided with a manhole giving access for cleaning the boiler
and tubes. The upper barrel has a steam dome and a manhole for cleaning the
boiler and tubes.
Small land stationary boilers of from 2 to 30 horse power have double return tubes
in a single shell the two sets being separated by a vertical division plate the ducts
or flues for reigniting the gases after passing through the first set of tubes being
provided as above mentioned
In the drawings I have shown flame tubes of the ordinary dimensions but I
would have it understood that tubes or flues of large dimensions may be used when-
ever required or when hard water is used and when large flues or tubes are so
used I provide metal rods for the transmission of heat the employment of such
metallic conductors being also a feature of improvement whatever may be the
system of boiler in which they may be applied.