Improvements in Instantaneous Steam Generators.
Year: 1897

page_text: Improvements in Instantaneous Steam Generators.
ELLS DAGNALL, 30, Maude Grove, Fulham, S.W., Engineer, ALFRED WILLIAM
SOUTHEY, 16, Elm Street, Gray's Inn Road, W.C., Electrical Engineer, do hereby
declare the nature of this invention to be as follows:
-
This invention relates to that class of steam generators in which the water is
instantaneously converted into steam, & it has for its object to overcome the objec-
tions applying to the systems as now used viz:-that the steam generated in this
manner has a very high temperature which causes damage to the engine, & the
small reserve of steam owing to the necessarily limited water, & steam space is
not always sufficient for restarting, when the engine & water pump are stopped.
Our invention provides means for increasing the water & steam space with safety,
thereby facillitating restarting, and by generating two classes of steam viz:-super-
heated & ordinary saturated which may be mixed as required avoiding damage
to the engine.
We carry our invention into effect by constructing our generator with circular
tubes (preferably of steel of thick section) in each tube we fit a second tube concen-
trically of such size as to leave only a small space between the walls of the tubes.
The inner tubes are fitted with connections, so that the water or water & steam
may circulate first through them, & they terminate at one end of the outer tube, so
that a free passage way is left for the water & steam to return through the space
between the tubes.
Connections are provided at both ends of the outer tube, by means of which the
water & steam may be allowed to circulate through the inner tube only, or pass
back through the space between the tubes as required.
The concentric tubes may be straight or curved if a number of tubes be used
they may be coupled up in series or parallel to suit requirements, & arranged so
that the central portions of the tubes only pass through the furnace, the connections
being outside the fire box.
When sets of tubes are arranged in series, the pipes from the ends of the outer
tubes from which the water & steam can be taken without passing through the
outer super heating tube, lead to the inner tube of the next pair, the return tubes
passing round the furnace, not through it, the supply being delivered to the first
inner tube.
When sets of tubes are arranged in parallel the pipes from both ends of the outer
tubes are connected in parallel, no return tubes passing round the furnace are
required, the supply being delivered to the inner tubes in parallel.
A body of water may safely be present in the inner tubes, as they are protected
from the excessive heat by the water.
To prevent saline deposits in the tubes, the inner tubes or a sleeve fitted round
them may be caused to rotate by the passage of the steam, acting on spiral faces
turned on the tubes or sleeves.
The water & steam delivered by the pipes leading from the return ends of the

page_text: outer tubes will necessarily be highly super heated but the steam drawn from the
opposite ends will be normally saturated, & the two classes of steam may be mixed
by means of ordinary valves as required.
The generator will be fitted with an ordinary safety valve but no guage glasses
or pressure guages etc. will be required.
Dated this 27th day of March 1897
Improvements in Instantaneous Steam Generators.
We, ELLS DAGNALL, of 30, Maude Grove, Fulham Road, in the County of
Middlesex, Engineer, and ALFRED WILLIAM SOUTHEY, of 16, Elm Street, Gray's
Inn Road, London, 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 that class of steam generator in which the water is
instantaneously converted into steam and has for its object to avoid the principal
objections to such generators viz: that the excessively high temperature of the
steam is liable to cause injury to the engine and that in consequence of the limited
capacity of the tubes the reserve of steam is so small as to be insufficient for re-
starting the engine after a stoppage of the engine and water pump. By our
invention the water and steam space may be so increased without liability to cale-
faction or the deposit of sediment which would otherwise ensue so as to ensure a
sufficient reserve of steam for re-starting, and saturated steam may be mixed in
any required proportion with the superheated steam in order to prevent injury to
the engine by the excessive temperature of the super-heated steam alone.
The invention is illustrated in the accompanying drawings forming part of this
specification wherein Figure 1 is an end elevation and Figure 2 a longitudinal
vertical section of the steam generator. Figure 3 is a part horizontal section of a
portion of a "head" and tubes and Figure 4 is a part longitudinal section of a
modified form of tube.
The improved generator consists of a set of straight steel tubes of circular section
cach comprising an outer tube a and inner tube 6 concentric with the outer tube a
and of such diameter as to leave an intervening annular space c. The inner tube b
communicates at one end with the intervening annular space c and the tubes are so
connected in series that the water, or water and steam, shall circulate through them
in succession entering each through the inner tube and returning through the
annular space, and so on through the whole of the tubes connected in series. The
connections are formed at the one end by a casting or header d of the form shewn
into which the tubes are screwed so that at this end there is no communication
between them but a passage e through the casting or header by which the annular
space c of the one tube connects with the inner tube 6 of the next in the row, the
superposed rows of tubes being also connected in series by the annular space of
the last of the lowermost row being similarly connected to the inner tube of the
first of the row above and so on, the last of the upper row being connected to a steam
drum f. At the opposite end the inner tube is merely made shorter than the outer
tube and its end left open, the end of the outer tube being closed by a plug g. The
inner tube b is fitted with a sleeve h preferably of phosphor bronze corrugated
helically so as to fit between the two tubes and acting as a baffle to cause the steam
and water to follow a helical course through the annular space and so cause a
scouring action on the sides of the outer tube whereby saline deposits in the outer

page_text: tube will be prevented. This helical sleeve is fitted loosely so that it is free to
rotate or to move longitudinally and so aid the scouring action of the steam by
the friction of the sleeve against the walls of the outer tube. The inner tube being
protected from excessive heat by the outer tube will not be liable to calefaction and
may therefore safely contain a considerable quantity of water, or water and steam,
whilst the small area of the annular space between the two tubes will prevent cale-
faction in the outer tube. Or the water and steam may be allowed to circulate
through the inner tube only, as shewn in Figure 4, especially in the case of the
tubes nearest the fire; the water hermetically held between the inner tube b' and
the outer tube a¹ preventing the outer tube being burnt either by the action of a
badly-regulated fire or during stoppages. The heat applied to the outer tubes will
be rapidly transmitted through them to the water contained in the inner tubes
through the agency of the water contained in the outer tubes.
The water is supplied by a feed pump worked by the engine and capable of being
also worked by hand at starting and is fed to the inner tube of the first of the lower-
most row and also to, say, the first tube of the uppermost or any intermediate row,
the feed being under the control of a three-way cock k by which the proportional
quantities of water entering at the two points and consequently the proportional
quantities of the two classes of steam may be regulated, the water supplied at the
second point escaping the action of the hottest portion of the generator and con-
sequently generating saturated steam which mixes with the superheated steam
coming from the lower rows of tubes, the result being a mixture of saturated and
superheated steam which may be used without injury to the engine. The regula-
tion of the water-feed may be automatically effected by means of a device controlled
by a pyrometer.
Having now particularly described and ascertained the nature of the said in-
vention and in what manner the same is to be performed we declare that what we
claim is:
1. The instantaneous steam generator wherein saturated and superheated steam
are generated in different parts of the boiler and mixed in any required proportion
as specified.
2. An instantaneous steam generator having concentric heating tubes in com-
bination with a helical baffle free to move in the intervening annular space, by
which the water, or water and steam, entering through the inner tube and
returning through said space is caused to follow a helical course substantially as
specified.
3. The instantaneous steam generator as described and shewn in the drawings.
Dand th: 94th dow of Dosombou 1907
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.