Improvements in Steam Generators.
Year: 1892

page_text: Date of Application, 28th Jan., 1892-Accepted, 19th Mar., 1892
COMPLETE SPECIFICATION.
Improvements in Steam Generators.
1, CHARLES DELL MOSHER, of Amesbury, County of Essex and State of
Massachusetts, United States of America, Gentleman, 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 :-
This invention relates to a boiler or steam generator comprising two water drums
located at or near the level of the grate, and at opposite sides thereof, two steam
urumis located above the water drums and at opposite sides of the centre of the fire
space above the grate, and bent tubes connecting the water drums with the steam
drums, some of said tubes being arranged close together in rows constituting walls,
while other tubes are separated by spaces and are arranged within the enclosure
surrounded by said walls.
The invention has for its object, first to enable a boiler or generator of the
general construction above mentioned to be treated as two separate boilers or
sections, each comprising one of the water drums, the tubes rising therefrom, and
the steam drum connected with the upper ends of said tubes, and each capable of
being shut off or disconnected from the other so that one part or section constituting
one-half or side of the boiler, may be supplied with more water than the other for
the purpose of increasing the weight of one side of the boiler and thereby counter-
acting the tendency of the vessel to take a permanent heel when impelled by a
single screw driven at a high speed. In high powered single screw vessels designed
to attain a high rate of speed the resistance offered by the water to the revolution
of the screw causes the vessel to take a permanent heel varying with the power
applied, hence by providing a boiler adapted to be separated into two sections and
loading one of said sections more heavily than the other I am enabled to readily
compensate for the tendency of the vessel to heel permanently, and keep the vessel
normally on an even keel.
My invention also has for its object to provide such an arrangement of the tubes
comecting the water and steam drums, as that the heated gases in passing among
said tubes in their course from the fire to the stack, will be prevented from acting
on the upper portions of said tubes, which portions, containing usually only steam,
are liable to be burned out by a degree of heat which will not injuriously affect
their lower portion containing water.
These results I attain by the improvements which I will now proceed to describe.
Of the accompanying drawings, forming a part of this Specification,
Figure 1 represents a partial end elevation and partial section of a boiler provided
with my improvement.
Figure 2 represents a section on line 2-2, Fig. 1.
Figure 3 represents a section on line 3-3, Fig. 1, and a top view of the portion
of the boiler shown in elevation in Fig. 1.
Figure 4 represents a section on line 4-4, Fig. 1.
The same letters of reference indicate the same parts in all the figures.
In the drawings:
a represents the grate of the furnace or fire-box. bb represent the water drums
located at opposite sides of the grate, and c c represent the steam drums elevated
above the water drums and located at opposite sides of the fire space over the
grate.
Each steam drum is located nearly or quite above a water-drum, although the
centres of the steam-drums are here shown as inside the vertical plane of the centres
of the water-drums, this arrangement being adopted because it is preferred to
arrange the outer sides of the steam drums directly over the outer sides of the

page_text: water-drums to accommodate the casing which incloses the whole apparatus, the
steam-drums being of larger diameter than the water-drums, so that their inner
sides project inwardly farther than the inner sides of the water-drums.
The water-drums are connected with the steam-drums by tubes rising from the
upper portions of the water-drums and entering the steam-drums above the centre
liues thereof. There are a large number of these tubes, and their lower ends are
connected with the upper portions of the water-drums. From the points of con-
nection with the water-drums the said tubes are bent inwardly and upwardly toward
the centre and upper portion of the furnace, and are then bent outwardly until they
join the inner sides of the steam-drums. There are two distinct series of tubes;
that is to say, the tubes connecting one water-drum with the corresponding steam-
drum are distinct from the tubes that connect the other water-drum and steam-
drum.
Each series of tubes comprises an outer row of tubes 5 arranged in close order so
as to form a practically continuous wall of tubes at the outer limit of the series,
said wall being close to the casing and serving to protect said casing from injury
by the heated gases. The tubes 6 6 6 at the inner side of the series are also
arranged to form a close or practically continuous wall, their lower ends being
arranged close together to prevent the gases from the fire-box from passing between
them, while above said lower ends said tubes are in contact with each other. The
wall formed by the tubes 6 extends from the end of the fire-box containing the fire-
doors o; c. the right hand end as viewed in Figures 3 and 4 partly but not entirely
to the opposite end, the inner tubes 7 7 7 at nearest the opposite end of the fire-box,
being staggered," or bent so that they are separated by spaces 8 (Figs. 1 and 3)
through which the products of combustion pass to the space between the outer and
inner tubes of the series. This arrangement presents a continuous wall of tubes 6
extending from the fire-door end of the fire-box compelling the products of
combustion to pass from said end as indicated by the full line arrows in Fig. 4,
partly to the opposite end of the fire-box, and a broken or open row of tubes 7
through which the products of combustion can pass to the space between the outer
and inner tubes, as indicated by the curved arrows, partly dotted, in Fig. 4, and by,
the arrows in Fig. 3.
The space between the outer and inner tubes contains a large number of separated
tubes 9, and constitutes a flue or passage along which the products of combustion
pass toward the fire-door of the boiler on their way to the stack g, as indicated by
the dotted arrows in Figure 1, the tubes 7 and 9 and the inner sides of the tubes 5
and 6 being acted on by the products of combustion passing through the fluc.
In the upper portion of said fluc is a transverse wall or battle-plate, composed of
several tubes 10 which are arranged in contact with each other and form a
continuous row or wall of tubes across the flue, (see Figs. 2 and 4), the location of
said wall being indicated by the dotted line ii in Fig. 4. Said walls extends from
the top of the casing d to about the level of the lowest portions of the steam-drums,
the tubes 10 that compose the wall or baffle plate arranged below said point so that the
products of combustion can pass freely between them as shown in Fig. 3. The
object of said baffle plate is to prevent the heated products of combustion from
rising to the highest part of the flue between the inner and outer tubes, the baffle
plate causing the current to dip downwardly and pass below the level of the steam-
drums before reaching the stack as indicated by the dotted arrows in Fig. 4. The
force of the draft, therefore, causes the main volume of the products of combustion
to flow in the most direct course toward the lower end of the battle plate and thus
prevents the more highly heated products of combustion from reaching the higher
parts of the tubes which contain chiefly steam, said higher parts receiving only
what is technically known as a "soaking heat" due to radiation and not to the
direct action of the current of hot gases. The lower portions of the tubes, including
those forming the baffle plate, which are subjected to the direct action of the
products of combustion, are filled with water, hence the hotter gases are directed
only on those tube surfaces which are in contact with water, the heat being therefore

page_text: applied to the best advantage. The baffle plate formed of tubes, as described, in
much more desirable than a solid plate not formed to contain water, it being free
from liability to be burned out. The water-drum b is connected with the water-.
drum by transverse pipes i extending across the fire box at the front and rear
ends of the grate. From each of these pipes rise a series of tubes 20 communicating
at their upper ends with the steam-drums, one half of the tubes from each pipe j
being connected with the drum c and the other half with the drum c'. The tubes 20
are arranged to form a close wall of tubes at the end of the fire box opposite the
fire door end, as shown in Fig. 3, said wall being interrupted or having an opening
formed at k, Figs. 1 and 3, by the bending of the lower portions of the tubes 20 to
accommodate a valve m hereinafter referred to. The tubes 20 at the fire door end
of the fire box do not extend across the fire box, their number being necessarily
limited to avoid the fire doors o.
It will be seen that the tubes are formed and arranged to expose their contents.
in the most favourable manner to the heat of the furnace, and at the same time.
enable the steam-drum to be located at a minimum height above the water-drum,
thus giving the generator a low centre of gravity, and making it in this respect
particularly desirable for steam launches and yachts and other craft in which
economy of vertical space is desirable in the steam generator. It will also be seen
that the employment of two steam-drums is essential to the above arrangement of
the tubes, because if a single steam-drum were employed the pipes could not be
disposed in the manner shown, so as to permit said drum to be at a minimum height
above the water-drums, and at the same time expose the tubes advantageously to
the fire, because if the tubes were arranged as here shown-that is to say, extending.
at an incline toward the centre and upper portion of the furnace and then curved
outwardly to enter the upper portion of the steam-drum-the generator would not
be evenly balanced, but would be heaviest on the side toward which the tubes are
inclined as they leave the water-drum.
The form of the tubes here shown and the duplicate steam-drums, which are
enabled by the form of the tubes to be brought down comparatively close to the
water-drums, are both essential to the production of a steam generator having a·
low centre of gravity.
The ends of the steam-drums are connected with the ends of the water-drums by
return pipes qq, for the return of water from the steam-drums to the water-drums.
Said return-pipes are located outside of the casing, as best shown in Figs. 1, 3
and 4, so that they are not subjected to the heat within the casing, but are kept
comparatively cool by contact with the external air; hence the descent of water
through the said return-pipes to the water-drums is facilitated, as will be readily.
seen.
There are two return-pipes for each steam-drum, and said pipes, besides main-
taining a uniform circulation, support cach drum at both ends, so that there is no
opportunity for either end to sag or be depressed.
Each steam-drum has a steam pipe and a suitable separator to separate the
entrained water from the steain. The ends of the steam pipes of the two steam
drums are connected by transverse pipes with the pipe that conduets the steam.
to the engine.
To enable the boiler above described to be divided into two distinct halves or
sections, cach having no connection with the other, I provide at the centre of each
pipe connecting the water-drums, a shut-off valve s, said valve being adapted to
entirely close the pipes jj so that water cannot pass from one drum to the other. I also
provide valves t adapted to shut off each steam pipe from the main pipe, said
valves being intended for use in case it is necessary entirely to discontinue the
use of one side of the boiler, as in case of the breakage of tubes or other disability.
In case of the discontinuance of the use of one side of the boiler, it will be
desirable to run the other side moderately to avoid liability of burning out tubes of
the discontinued side.
It will be seen that when the valves are closed the two sides of the boiler may

page_text: be treated as independent boilers, either half of the boiler being adapted to be shut
off wholly from the other half and from the steam pipe in case of disability.
This is an important advantage since it obviates the necessity of stopping the
engine when one half of the boiler and not the other is disabled.
Another important advantage resulting from the divisibility of the boiler into
two sections is that both sides may be kept in operation, one side being supplied
with more water than the other, to trim the vessel when the revolution of the screw
at a high speed tends to give the vessel a permanent heel, the fact being, as
previously stated, that in very high powered single screw vessels, such as the latest
torpedo boats, the resistance of the water to the revolution of the screw gives the
vessel a permanent heel, the angle of which varies with the work on the screw.
It
will be seen, therefore, that by the described construction of the boiler whereby a
preponderance of water may be accumulated in either side of the boiler affords a
convenient and easily controlled means for correcting the tendency of the vessel to
heel under the influence of the screw. When the vessel is running at moderate
speed, the tendency to heel does not exist and the valves s may then be opened and
permit communication between the water-drums so that the whole may be run as
one boiler.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :
1st. As an improvement in a boiler or steam generator composed of water-
drums, steam-drums c c', and tubes connecting said water-drums with the
steam-drums, some of said tubes being arranged to form walls enclosing flues or
passages extending along the sides of the fire box and adapted to conduct the
products of combustion from one end of the fire box to a stack over the opposite
end of the fire box, the improved baffle plates formed to obstruct the upper portions
of said flues, said baffle plates being composed of tubes formed and arranged to
constitute walls extending across the upper portions of said flues, the lower portions
of said tubes being separated to permit the free passage of the products of combustion
below said baffle plates, as set forth.
2nd. A boiler comprising in its construction two water-drums, two steam-drums
located above the water-drums, pipes connecting the water-drums, return pipes
connecting the water and steam-druins, tubes connecting the water-drums with the
steam-drums, each water-drum being connected with the corresponding steam-drum
by an independent series of tubes, and means for shutting off the communication
between the two water-drums, whereby the boiler may be divided and treated as
two independent boilers, as set forth.
3rd. A boiler comprising in its construction two water-drums, two steam-drums
located above the water drums, return pipes connecting the water and steam-drums,
transverse pipes connecting the water-drums, valves in said pipes whereby com-
munication between the two water-drums may be shut off, tubes connecting the
water-drums with the steam-drums, and steam pipes to conduct steam from the
steam-drums, each of said steam pipes having a valve whereby it may be shut off,
the valves in the water-drum-connecting pipes and in the steam pipes enabling
either side of the boiler to be entirely cut off from communication both with the
other side of the boiler and with the engine, as set forth.
CN
1001
CHARLES DELL MOSHER.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.