Improvements in Steam Boilers.
Year: 1890

page_text: Date of Application, 5th Mar., 1890
Complete Specification Left. 14th Nov., 1890-Accepted, 10th Jan., 1891
PROVISIONAL SPECIFICATION.
Improvements in Steam Boilers.
I, THOMAS ELWELL, of 1940, Avenue de Paris, La Plaine de St. Denis (Seine),
France, Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in steam boilers and more particularly to
those of torpedo-boats, cruisers, and other vessels.
It is often found, with this class of boiler, that it is impossible to so proportion the
elements or principal dimensions of the boiler as to obtain a maximum production of
steam with regard to the space occupied as well as realise such conditions of working
as are compatible not only with the due preservation of the boiler but also with the
security requisite in such cases. The difficulty of reconciling these several requirements
becomes the greater the higher the required speed, to attain which both an increase in
the power of the engines and greater fineness in the lines of the hull are necessary, so
that the weight and dimensions are consequently limited. This is more especially
evident in torpedo-boats, recent trials having proved that their boilers are, notwith-
standing the care taken in their construction, incapable of responding to the exigencies
of working with the forced draught necessary for attaining the desired speed. The
imperfections of all boilers placed under similar conditions are evident and the
numerous palliatives proposed for improving their resistance to extreme heat serve to
shew the difficulty of the problem. None of the improvements hitherto suggested
would appear to have solved the question, and the greater part of them consist in
additions to the boiler which are liable to be quickly destroyed by the action of heat
and which are in some cases of a nature to lessen the steam-generating capacity
of the boiler.
The improvements which form the object of the present invention are based exclusively
upon the employment of means which cannot in any way lessen, but will even increase,
the efficiency of the boiler. Experience has shewn that the weak point in boilers of
this kind lies in the difficulty of keeping the tubes tight in the firebox tube plate
(whatever may be the metal of which the tube plate or tubes are made) owing to the
expansion of the tube plate under a too-sudden rise of temperature, the loosening of
the tubes being facilitated by the concurrent expansion of the tubes which, not being
able to bend, exert a thrust upon the tube plate tending to loosen the ferrules.
Whatever may, however, be the cause it is acknowledged that the chief end to attain
is the prevention of the overheating of the front tube plate which is due in a great
measure to the insufficient cooling of the rear face of the plate by the water in the
boiler owing to the insufficient circulation of the water impeded by the tubes so that
steam is more often in contact with the plate than water. The present invention
ensures a sufficient circulation of the water in contact with the tube plate and at same
time sweeps off the globules of steam whose ascension may have been obstructed by
the flues.
Reference is to be had to the accompanying drawing which illustrates my invention
by way of example, the boiler being in longitudinal section.
At a suitable distance in rear of the front tube plate A, I place a division plate C,
through which the tubes pass. This division plate, which may, or may not, be fixed
to the boiler shell and tubes, does not extend up, say, beyond the low water level of
the boiler so as to leave a free passage for the steam. An energetic circulation of
water in contact with, and in the immediate neighborhood of, the front tube plate A
of the fire box is ensured by the use of a rotary pump; ejector, turbine, or other
circulator, E which draws the water through a pipe from the rear side of the partition
and delivers it at the front side. In the example shewn, the water is drawn from

page_text: point F close to the rear tube plate B and delivered again to the boiler at one or
more orifices D.
The feed water may also be made to serve, either wholly or in part and either
concurrently or separately, for cooling the front tube plate it being, for this purpose,
introduced by a separate pipe direct from the feed pumps; or the water may be
previously heated by causing the feed pipe to pass through the boiler; or it may
be mixed with the water in course of circulation. The division may be so arranged
as to allow of the two compartments of the boiler being more or less completely
separated from, or put in communication with, each other so as not, in certain
cases, to prevent the natural circulation of the water in the boiler. The tubes may
be "dudgeoned" into the partition which will receive a part of their thrust and
correspondingly relieve the front plate. With the same object, the tubes may be
drawn of two diameters the smaller of which would correspond to the front compart-
ment so that, while they may be inserted from the smoke box end, they will take a
bearing against the partition.
The auxiliary circulation apparatus E may, in certain cases, be made to serve as an
auxiliary bilge pump, fire engine, or otherwise.
Tata thin 5th 1ML 100
COMPLETE SPECIFICATION.
Improvements in Steam Boilers.
I, THOMAS ELWELL, of 194bts, Avenue de Paris, La Plaine de St. Denis
(Seine), France, Engineer, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement :-
This invention relates to improvements in steam boilers and more particularly to
those of torpedo-boats, cruisers, and other vessels.
.
It is often impossible to so proportion this class of boiler as to obtain a high pro-
duction of steam for the space occupied and also ensure such conditions of working
as are compatible with the safety and due preservation of the boiler. The difficulty of
reconciling these conflicting conditions is increased the higher is the speed to be attained,
since to obtain increased speed involves greater power of the engines and finer lines
of the hull, thus necessarily limiting the weight and dimensions of the boiler. This
is mort especially evident in torpedo-boats of which the boilers have proved incapable
of enduring the forced draught necessary for attaining the required speed. The
imperfections of all boilers placed under similar conditions are evident, and the
numerous palliatives proposed for enabling them to endure the extreme heat shew
the difficulty of the problem. None of the improvements hitherto suggested would
appear to have solved the question and most of them consist of adjuncts which are
liable to rapid erosion by the action of heat and in some cases have the effect of lessen-
ing the steam-generating capacity of the boiler.
The effect of the present invention is to increase, rather than diminish, the efficiency
of the boiler. The weak point in such boilers is the loosening of the tubes in the fire-
box tube plate by the concurrent expansion of the tube plate and tubes when too
suddenly heated, the tubes, not being able to bend, exerting a thrust which tends to
loosen the ferrules. However this may be, it is essential to prevent the overheating
of the front tube plate consequent on defective circulation of the water within the
boiler impeded as it is by the tubes, so that steam is more often in contact with the
plate than water.
The present invention ensures a brisk circulation of the water whereby the globules
of steam whose ascension may have been obstructed by the flues are forcibly swept
off the tube plate.

page_text: Reference is to be had to the drawing filed with my Provisional Specification
which illustrates my invention by way of example, the boiler being in longitudinal
section.
At a suitable distance from the front tube plate A in the water space of the boiler,
there is a division plate C through which the tubes pass. This division plate may, or
may not, be fixed to the boiler shell and tubes and does not extend up, say, beyond
the low water level of the boiler and thus serves to divide the water-space of the boiler
into two compartments. A forced circulation of water, in contact with, and in the
immediate neighborhood of, the fire box tube plate A, is maintained by means of a
rotary pump, ejector, turbine, or other water circulator, E connected by pipes with
the two compartments which draws the cooler water from the rear compartment and
delivers it into the front one. In the example, the water is drawn from a point F
close to the rear tube plate B, and delivered at one or more orifices D between the
partition and the front tube plate A. The feed water may also be applied either
wholly or in part to cool the front tube plate by being introduced through a separate
pipe, either direct from the feed pumps or after being heated by passing through a
pipe traversing the boiler. Or the feed water may be mixed with the water in course
of circulation as above described, that is to say the two streams may be applied
separately or conjointly.
The division plate may in some cases be so formed that the two compartments of
the boiler are so far in communication with each other that the natural circulation of
the water in the boiler is permitted. The tubes may be "dudgeoned" into the
partition which will receive a part of their thrust and correspondingly relieve the
front plate. With the same object, the tubes may be drawn of two diameters,
the smaller of which would correspond to the front compartment so that while they
may be inserted from the smoke box end they will take a bearing against the partition.
The forced circulation apparatus E may in certain cases be made to serve as an auxiliary
bilge pump, fire engine, or otherwise.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
:-
The employment, in a steam-generator, of a partition plate between the front and
rear tube plates and of apparatus whereby a forced circulation of the water is
maintained between the two compartments, substantially as and for the purpose
specified.
Dated this 14th day of November 1890.