Improvements in Steam Boilers.
Year: 1889

page_text: Date of Application 13th May, 1889
Complete Specification Left, 14th Aug., 1889-Accepted, 21st Sept., 1889
PROVISIONAL SPECIFICATION.
Improvements in Steam Boilers.
We JAMES RAWLINSON and SAMUEL CLARE RAWLINSON both of the Elms,
Gorsebrook, Wolverhampton in the County of Stafford, locomotive engine men,
do hereby declare the nature of our invention to be as follows:-
This invention has for its main object the improved construction of a boiler of the
locomotive type, whereby greatly increased strength is secured, permitting a greatly
increased steam pressure, and increased steam space is provided in proportion to the
water space, such space being mainly divided off from the water space, the tendency
to priming being thus greatly reduced. The invention, however, is applicable or
partly applicable, also to steam boilers generally.
We will describe the invention with reference to a locomotive boiler, when its
application, or application in part, to other types of boilers will be readily under-
stood. The barrel of the boiler is formed of two concentric shells. The inner of
these shells corresponds with the ordinary barrel of a locomotive boiler, and is
fitted with the ordinary flue tubes, and, when in use, is filled with water to above
the level of the tubes. The annular space formed between the two shells is a
steam space, and the steam generated in the inner shell passes through an opening
in the top thereof into a dome fitted on the top of the outer shell and thence into
the annular steam space between the two shells, from whence it passes to the
cylinders through a pipe connected at its front end, preferably at or near the top.
No steam pipe is thus required inside the boiler. The shells are stayed together by
means of stays in the manner in which the inner and outer plates of the fire-box
are usually stayed. The inner shell is thus supported by the pressure of steam around
its outer circumference against the pressure within it, and lends the whole of its
strength therefore to assist the outer shell in resisting the pressure within such
latter shell. The barrel is thus extremely strong and permits of a very much
bigher pressure of steam being used than when formed of a single shell in the
ordinary manner
The tube-plate is carried up, and also formed of such shape sideways, that the
hinder end of the inner shell may be fixed to it. The outer plate of the top of the
fire-box is carried across as a Hat plate, and is stayed to the crown or inner plate of
the top of the fire-box by means of stays, just as the inner and outer side plates of the
fire-box are usually stayed together, and thus the two plates support one another
against the internal pressure. The forward edge of the upper plate is rivetted to the
tube plate. It is preferred, for the sake of appearance, and to aid in supporting the
weight of the fire-box, to carry an arched or curved plate over the top of the upper
plate last mentioned; but the space thus formed is not in communication with the
steam or water space of the boiler, and thus no downward pressure is brought upon
the upper plate of the fire-box crown. The space thus formed between the arched
plate and the top plate of the fire-box crown may be used for the passage of tubes to
the gauges, and for such like purposes. Openings through the tube-plate communicate
between the water space above the fire-box and the interior of the inner shell, and
openings communicate through the lower side of the inner shell with the water space
at the forward side of the fire-box.
In the opening through which the steam escapes from the inner shell is fitted a
suitable valve seating, on which is seated a valve. This valve has an opening through
it for the passage of the steam, and carries on its under face a ball or other Hoat. In
its normal position this ball or other float rests upon a suitable guard in such position
as to be clear of the opening through the valve, and admits of the flow of steam

page_text: through the valve into the annular steam space; but, if a wave passes under such
float, so as to come in contact therewith, or if the water splashes towards the opening
through the valve, the float is, thereby raised against the valve and prevents the water
splashing through into the steam space; when, however, this takes place the valve
itself is raised by the pressure of steam and allows the steam to pass up between
its periphery and the circular wall of the baffle-plate.
There is, of course, some tendency for the steam to condense in the annular space
between the inner and outer shells, and the condensed water collects in the lower
portion of such space. A number of flue tubes are carried from the tube plate to the
smoke box through the lower portion of this annular steam space, in order to cause
the re-evaporization of such condensed water. These flues may be closed, when
desired, by means of a plate at the front thereof which is suitably connected by a rod
with a handle at the foot-plate.
The application, or application in part, of this invention, to other descriptions of
boilers will now be readily understood. In the case, for instance, of a Cornish or
Lancashire boiler, heated only by means of the internal flue tube or tubes the main
barrel thereof would be made of an inner and outer shell, substantially as and for the
purpose described with reference to a barrel of the locomotive type. In this case a
flue may be carried below the external shell to evaporate any condensed water which
may collect therein. If, however, such a boiler, constructed with a double shell
according to this invention, is required to be heated externally also, as is usually the
case, or if a double shell is used, as it may be according to this invention, for an
externally fired boiler, the annular space between the shells is in communication
with both the water and steam spaces of the inner shell, so that such annular space
would contain water up to the level of the water in the inner shell.
Dated this 11th day of May 1889.
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Steam Boilers.
We, JAMES RAWLINSON and SAMUEL CLARE. RAWLINSON, both of The Elms,
Gorsebrook, Wolverhampton in the County of Stafford, locomotive engine men, 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 has for its chief object an improved construction of boiler of the
locomotive type (that is the type in which a fire-box is employed at one end of the
boiler from which the products of combustion pass through internal tubes to a
smoke box at the other end) whereby the strength is greatly increased thus permitting
the employment of very high pressures, and whereby increased steam space is
provided in proportion to the water space and is mainly divided off from the water
space, the tendency to priming being thus greatly reduced. The invention is,
however, in part applicable also to steam boilers generally.
The main feature of the invention consists in forming the cylindrical portion or
barrel of a boiler, whether of the locomotive or other type, of an inner and outer
shell. The space formed between the two shells is (in a greater or less degree as
hereinafter described) a steam space, and the steam generated in the inner shell
passes through an opening in the top thereof into the steam space between the shells.
The shells are stayed together by means of stays in the manner in which the inner
and outer plates of the fire-box of a boiler of the locomotive type are usually stayed
together. The inner shell is thus supported by the pressure of steam around its
outer circumference against the pressure within it and lends the whole of its strength
therefore to assist the outer shell in resisting the pressure within the latter shell.

page_text: The barrel is thus extremely strong and permits of a very much higher pressure
of steam being used than when formed of a single shell in the ordinary manner.
inner of the shells is fitted, in the case of a boiler of the locomotive type or of other
The
internally flued boiler, with the ordinary flue tubes.
A feature of this invention, which is of considerable importance also, in the case
of a boiler of the locomotive type, consists in staying the outer plate of the top of
the fire-box to the crown or inner plate by means of stays just as the inner and outer
side plates of the fire-box are usually stayed together, and thus the two plates support
one another against the internal pressure. For this purpose, when the crown plate
is flat, as is usual, the outer plate is carried across as a flat plate also, instead of being
arched as usual. Both the crown plate and outer plate may, however, be somewhat
curved or cambered, if desired.
We will now describe the invention specially with reference to the drawings
herewith, which illustrate a locomotive boiler with our invention applied thereto.
Figure 1 is a longitudinal section through the centre of the boiler, figure 2 a sectional
plan taken on line of figure 1, figure 3 a vertical section through the fire-box
taken on line of figure 1, figure 4 a sectional plan taken on line of figure 1,
and figure 5 a side elevation shewing the hinder end of the barrel and the forward
end of the fire-box. The barrel of the boiler is formed of an inner shell A, and of an
outer shell B, the shell A being carried preferably concentrically within the shell B.
An annular space a is enclosed between the exterior of the inner shell A and the
interior of the outer shell B. This space a is a steam space, and the steam generated
in the shell A passos through an opening in the top thereof into a dome C fitted on
the top of the shell B, and thence into the annular space a between the two shells,
from whence it passes to the cylinders through a regulator box connected at its front
end preferably at or near the top. No steam pipe is thus required inside the boiler.
The shells A and B are stayed together by means of stays & which correspond to the
stays usually employed in the sides of fire-boxes, but as the parts which are stayed
together in this case are of a curved form the stays may be spaced further apart
than in the case of the fire-box stays. Ordinary fue tubes e are fitted within the
shell A.
The shell A is fixed around its entire circumference at its hinder end, to the tube-
plate D. The shell B is fixed around its upper portion at its hinder ond and for a
considerable distance down on each side, as shewn, by means of a projecting part g
riveted to a backwardly flanged part h of the tube plate, and for this purpose the tube-
plate is carried up to the top of the boiler and is made to the diameter of the boiler at
its upper ond. This shell is fixed around its underside at its hinder end, by means of
an angle iron i, to the plate H in front of the water space around the fire-box, as
shewn in section by figure 1 and in side elevation by figure 5. The water space
around the fire-box is completely cut off from connection with the annular steam
space a by means of the plate H, as shewn more especially by figure 7 which is a side
elevation corresponding to that shewn by figure 5 but with the shell B and the outer
ide plate of the fire-box removed. The plate H has an outward flange a' by which it
s riveted to the shell A. The outside edges of the plate H are formed with backward
anges. The forward sides of the outer side plates of the fire-box are riveted to
hese flanges &', and the top corners of such side plates are riveted also to the lower
nds of the flange / of the tube plate. An enlarged sectional view through one side
f the boiler, taken on line ¹¹ of figure 5, is shewn by figure 8. In this view a
ange c is formed on the plate H to bed against the back of the angle iron d' by
hich the shell A is fixed to the tube plate, and the plate H is shewn at its upper
nd as rivetted through the part a¹ to the shell A, and as also fixed to such shell
ad to the tube plate D by means of rivets passing also through the angle iron d.
he joint between the plate H and the inner and outer shells and the tube plate will
w be quite clearly understood by reference to figure 9, which is a front view of
ch joint on one side, with the tube plate and the angle iron d¹ omitted. The
ckwardly flanged part of the tube plate is indicated by broken lines. The
be plate D, while made of the diameter of the outer shell at its upper end is
+

page_text: made of the usual width only for the remaining portion, as shewn by figure 4
(and by broken lines at a figure 9), so as to allow thorough circulation between the
water spaces at the sides and front of the fire-box.
The outer plate E of the top of the fire-box is carried across parallel with the
crown plate F (see more especially figures 1 and 3), and is stayed to such plate F
by means of stays corresponding to the stays used at the sides of the fire-box.
The forward ends of both the plates E and F are fixed to the tube plate.
A wide opening & is formed through the tube-plate to communicate between the
water space above the crown of the fire-box and the interior of the shell A, and a
number of small openings (corresponding to the opening 'm figure 1) are formed
through the lower side of the shell A to communicate with the water space between
the plates D and II of the fire-box.
The ordinary longitudinal stays are dispensed with, as they are unnecessary when
the boiler is constructed as above described, but a stiffener ' is carried across the
inside of the flat surface of the front end plate above the flues.
It is preferred, for the sake of appearance, and to aid in supporting the weight
of the fire-box, to carry an arched or curved plate over the top of the plate E;
but the space thus formed is not in communication with the steam or water space
of the boiler, and thus no downward pressure of steam is brought upon the plate E.
The space thus formed between the arched plate G and the flat plate E may be used
for the passage of tubes to the gauges, or for such like purpose.
As considerable steam space is provided between the inner and outer shells the crown
of the fire-box may be carried higher than is usual in the ordinary construction
of boiler of the locomotive type, and thus notwithstanding that the inner shell is
somewhat less in diameter than with an ordinary boiler of the same external
dimensions, the same number of fluo tubes may be employed.
The tube plate carried up to the top of the boiler, with the outer shell and also the
outer top plate of the fire-box fixed thereto, greatly increases the strength aud stiffness
of the boiler, and this plan may be adopted in the case of boilers of the locomotive
type generally, the ordinary single shell being in such case fixed around its upper
portion to the tube plate.
For convenience in passing the outer shell over the front end plate e' such plate is
formed of a diameter to give a clearance all round for the rivet heads inside the outer
shell, and when such shell has been placed in position a ring g¹ (see figure 10, which
is an enlarged section of the joint at the outer ends of the shells) is pushed into the
annular space thus left between the circumference of the plate and the inner surface
of the outer shell. In order to give ample space between the shells at their outer
ends for the joint, it is preferred to make the outer ring of plates of the inner shell of
a diameter to enter inside the next adjoining ring.
A ball
In the opening through which the steain passes from the shell A is fitted a valve
seating or narrow ledge n upon which rests a plate or valve y having an opening q
through the centre thereof of an area sufficient for the passage of the steam.
or float P, which may be conveniently made of metal hollowed to give it lightness, is
carried in a guard or cradle o.dependling, from the valve 7, and in its normal position
this ball rests in the bottom of the guard clear of the opening through the plate
and admits of the flow of steam through the opening g', which passes thence over the
top of the battle-plate J, and through openings in the outer shell, into the steam
space a but if a wave passes under the Hoat, so as to come in contact therewith, o
if the water splashes towards the opening g', the float is thereby raised against th
plate g and closes the opening g' therethrough and thus prevents the water splashin
through into the steam space; when, however, this takes place, the plate itself i
raised by the pressure of the steam and allows the steam to pass between its peripher
and the circular wall of the baffle plate, but the valve and ball fall again almo
instantaneously.
There is, of course, some tendency for the steam to condense in the annular space
A number
and the condensed water collects in the lower portion of such space.
flue tubes (see figures 1 and 3) are carried from the tube plate D to the smoke bo

page_text: through the lower portion of the steam space a in order to cause the re-evaporization
of the condensed water. These flues may be closed, when desired, by means of a plate
or damper at the front thereof suitably connected by a rod with a handle at the foot-
plate. A damper suitable for the purpose is shewn by figure 6, which is a front
elevation of the lower portion of the front of the boiler bat with the ordinary flue
tubes omitted. A curved plates is carried in guides s, and has openings & there-
through corresponding with the ends of the tubes (shewn by broken lines as when
closed by the damper). The damper may be moved endways by means of a rod
passing through one side of the smoke box and connected by suitable gear with a
handle at the foot-plate. It will usually be found preferable to keep the tubest covered
with water, and for this purpose a communication may be made by means of a small
pipe, having a tap thereon for regulating the supply, between the water space of the
shell A and the lower portion of the steam space a, and a gauge glass may be fixed to
the lower side of the shell B by means of which the height of the water in such space
may be observed. In ordinary working the dampers may be kept closed, and be
opened only when it is necessary to evaporate some of the water in the space a to
maintain a proper capacity for the steam, or when an extra pressure or supply of
steam is required.
A convenient apparatus for opening and closing a passage for the flow of water
from the inner to the outer shell, and of regulating such flow, is shewn, to a scale of
half size, by figure 11 in which is a tubular case screwed into both the outer shell B
and the inner shell A. An opening communicates with the interior of the shell A,
and an opening with the space between the shells. The opening k¹ is closed and
opened, and the flow of water regulated, by means of a plug operated by a handle n'.
The plug is screwed through a part o¹ of reduced internal diameter, and leakage past
the plug at the outer end is prevented by a gland på pressed by means of a screwed
cap against a packing is a lock-nut which securely locks the case in
position.
The method above described of constructing the cylindrical part or barrel of the
boiler is applicable to other descriptions of boilers, as will be readily understood.
In the case of a Cornish or Lancashire boiler heated only by means of the internal
Alue tube or tubes the main barrel thereof would be made of an inner and outer
shell, substantially as described. In this case a brick flue may be carried below the
external shell, for a corresponding purpose the tubes t before described. If,
however, such a boiler, constructed with a double shell according to this invention,
is required to be heated externally also, as is usually the case, or if a double shell
as above described is used for an externally fired boiler, the space between the shells
is preferably in constant communication with both the water and steam spaces of the
inner shell so that such space between the shells would contain water up to the level
of the water in the inner shell.
Large internal flue tubes of boilers may be formed of an inner and outer shell as
described in the case of a boiler barrel, and be correspondingly stayed to one another,
by which means a very strong internal flue tube is obtained. In this case the space
between the two shells must be in communication with the water space so that the
inner shell shall at all times be surrounded with water, and openings should be formed
both through the lower and upper sides of the outer shell to facilitate circulation of
the water in the space between the shells.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. A steam boiler of which the cylindrical part or barrel is formed of an inner
and outer shell suitably stayed together, substantially as and for the purpose set
forth.
2. In a steam boiler, an internal flue tube formed of an inner and outer shell
suitably stayed together, substantially as and for the purpose set forth.

page_text: 3. In a steam boiler of the locomotive type, the crown plate of the fire-box stayed
to the outer top plate in the manner in which the inner and outer side plates of the
fire-box are usually stayed together.
4. In a steam boiler of the locomotive type having the usual flat crown to the
fire-box, an outer top plate also formed flat to pass over the crown plato and stayed
to such crown plate in the manner in which the inner and outer side plates of the
fire-box are usually stayed together.
5. In a boiler of the locomotive type, the tube plate carried to the top of the
boiler, and the boiler shell, or both the inner and outer shells when such are
employed as described, and also the outer top plate of the fire-box, fixed thereto,
substantially as described.
6. In a steam boiler, a steam space formed as divided off from the main water
space by means of an outer shell around an inner shell, substantially as described.
7. In a steam boiler of the locomotive type in which an inner and outer shell are
employed for the purpose set forth, flue tubes passing through the lower portion of
the space enclosed between the shells, and preferably provided with a damper,
substantially as described for the purpose set forth.
8. A boiler of the locomotive type constructed substantially as described with
reference to the drawings herewith, for the purpose set forth.
Dat his and dave of Au 1980
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicants.