Year: 1888

page_text: I. EDWIN CHAMBERS JOHN DEVIS, of the Athenæum, Glasgow in the County
of Lanark, North Britain, Engineer 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 improvements in the Design and Construction of certain
types of steam Generators_especially those known as the Locomotive type and the
return-tube marine type. The objects of my said Invention are in the case of the
Locomotive-type to simplify and cheapen the construction, to préserve as far as
possible the advantages and to eliminate the disadvantages of this type as usually
constructed and in the case of the return-tube type to diminish the weight both of the
boiler and of the contained water and to provide a means of modifying the shape of the
boiler according to the space available for it.
The illustrations annexed show several of, but not all, the forms which my Invention
takes. In each of these, the main part of the boiler shell is made in segments of
cylinders and stayed through opposite intersections of the segments. In the primary
form of the locomotive type there are two segments, in the lower of which is placed
the firebox which is also cylindrical in general form but may be corrugated or other-
wise stiffened. The water space round the firebox is not crossed by any stays so that
the leakage at the firebox stays and the collection round them of dirt and rubbish
entering with the feed water, which gives so much trouble with the usual, boiler of
this type, is entirely avoided and as there are also no stays to the crown of the firebox
it is easy with a manhole in the front plate, to get perfect access to the steam space
over the firebox and thence to pass along the barrel, even in a small boiler, while in a
boiler of this type as usually constructed it is quite impossible to get into the steam
space over the firebox and it is only possible to get into the barrel when the boiler is
of considerable size or by removing some of the tubes. This accessibility therefore I
claim as a valuable improvement and it is shared by all the modifications included
under this Invention. The above remarks also as to the generally cylindrical firebox,
corrugated or otherwise stiffened, when desired, and as to the waterspace round the firebox
apply to all the modifications. There being in my boilers no stays round the sides of
the fire boxes, the latter are free to expand and contract without causing excessive local

page_text: stresses hence the boiler is more durable than the kind generally in use and also
because while in the latter there are considerable local deflections under pressure in
the main parts of the boiler, the front shell and fire-box, in mine there are no such
deflections, all stresses being exactly balanced.
In order that my Invention may be properly understood and readily carried into
effect I will now proceed to describe the drawings hereunto annexed.
The illustrations do not show the whole of the barrels of the boilers as my Invention
does not apply to that part of the boiler.
In Figures 1 and 4 the firebox is a complete cylinder with a water space round the
bottom.
In Figures 2 and 3, the firebox is a segment of a cylinder connected to the shell
along its lower edges, the intersections of shell and firebox being connected and tied
together either by bars or by a plate which latter may also serve as an ash plate.
In Figures 1 and 2 the tubes are taken direct from the firebox; in Figures 3 and 4,
the firebox is expanded at the back into a combustion chamber from which the tubes
are taken, the object of the combustion chamber being to allow of greater freedom of
expansion and contraction in the firebox and to allow of the latter, together with the
shell, being diminished in width without diminishing the number of tubes.
For sizes of boilers in which a single furnace becomes inconvenient, I use two or
moro, when the boiler may be made either as shown by Figure 5, 5*, where the
separate furnaces lead into a single combustion chamber from which the tubes pass
through a single barrel, the shell being of the same form as in Figures 1 and 4, or
as in Figures 6, 7, 8 and 9, where there is one barrel to each furnace and the shell
consists of a number of segments depending chiefly on the number of furnaces and
stayed at their intersections by approximately vertical stays passing between the
furnaces. These multiple-barrel modifications may be made with dry bottoms as
shown in Figures 7 and 8, or with wet bottoms as shewn in Figures 6 and 9, without
combustion chambers as shown in Figures 6 and 7 with a separate combustion chamber
to each furnace, or with combustion chambers common to two more or all furnaces
as shown in Figures 8 and 9; in the last case it is convenient to pass one vertical
stay in each row through a water tube intersecting the combustion chamber and in
some cases two stays; also any one of these modifications may be made either with
horizontal transverse stays over the furnaces, as shown in Figures 6 and 7, or
without them as shown in Figures 8 and 9.
Beside the advantages already claimed for my Invention, the multiple-barrel modifi-
cations last described, enable a large boiler power to be arranged without incon-
venience, in spaces where the head room is small, as for instance between the decks,
and under the water line, of small craft intended for high speed; in the basements of
buildings &c.
.
I prefer to put a manhole in the front end over the furnace and to flange the
front end to connect to the furnace but in some cases I rivet the furnace to a
separate plate with a water space between it and the front plate as in the ordinary
Locomotive type of boiler. In some cases I place the firing hole at the side of the
furnace instead of at the front and in some cases I use two barrels to one furnace,
one at each end.
As applied to the return-tube type my Invention in the form I prefer, is similar
in general form to Figure 6, but of course without barrels, the return tubes taking
the place of one or more of the furnaces, and the top tubes being on about the same
level as the furnace crown or crowns. This is shown in Figure IU, in one form, but
I claim for the return tube type all modifications applicable to it and described
herein before for the Locomotive type.
The longitudinal rivetted joints may be made in any of the usual ways and arranged
between the lines of stays, or they may be made of any convenient scollop form,
either lapped or butt strapped and arranged on the lines of stays, this latter being a
simple way of giving the requisite stiffness to the sheet plates between the stays and
of preserving a large percentage of the tensional strength of the plate.
Two forms of the scollop joint described are shown in Figures 11 and 12 the

page_text: advantage of the one shown in Figure 12, being that the scollop can be cut out by
machine.
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. In Locomotive type of boilers the construction of the whole firebox of a
single complete cylinder, and the front shell of two cylindrical segments as shown in
Figure 1.
2nd. The construction of the whole firebox of a single cylindrical segment and the
front shell of one cylindrical segment at the top and two at the bottom, the latter
being attached along their lower edges to the lower edges of the firebox and tied/
across the bottom of the latter as shown in Figure 2.
1,
3rd. The combination with each of the above described arrangements, of an
enlargement of the firebox at the back end thereof, forming a combustion chamber
as shown in Figures 3 and 4.
4th. The arrangement and construction of two or more cylindrical fireboxes
leading into a combustion chamber from which the tubes pass through a single
barrel, the front shell being made of two cylindrical segments, as shown in
Figure 5, 5.
5th. The arrangement and construction of two or more cylindrical furnaces side
by side, from which the tubes pass through separate barrels, one barrel to each
furnace, the front shell being made in a number of segments connected at their
intersections by approximately vertical stays passing between the furnaces, and
horizontal transverse stays passing above the furnaces as shown in Figure 6.
6th. As a modification in the carrying out of the arrangements shown in Figure 6,
dispensing with the lower parts of the furnaces and shell as shown in Figure 7, and
described with reference to Figure 2.
7th. As a modification of both of the arrangements shown in Figures 6 and 7,
dispensing with the horizontal transverse stays by the arrangement and construction
of the shell as shown in Figures 8 and 9.
8th. As a modification applicable to the above arrangements, leading the tubes
from ono or more combustion chambers each common to two or more furnaces as
shown, in some forms, in Figures 8 and 9, in which case there may be one barrel
to each furnace, as described, or one barrel may be common to two or more furnaces.
9th. As a modification applicable to the same arrangements, the employment of a
separate combustion chamber to each furnace.
10th. In return-tube boilers the arrangement and construction of the shell in
cylindrical segments stayed at their junctions by approximately vertical stays as
described with reference to the Locomotive-type of boiler shown in Figure 8, but
with the place of any one or more furnaces occupied by return-tubes as shown in
Figure 10.
11th. As a modification applicable to the said arrangement, the employment of
horizontal stays and the construction of the front shell approximately similar in shape
to that shown in Figure 6.
12th. In combination with my Improvements all as hereinbefore described, the
employment and arrangement of scollop rivetted joints on the lines of the shell stays
as shown in the two forms, Figures 11 and 12.