Improvements in Instantaneous Steam Generators.
Year: 1890

page_text: Date of Application, 2nd Aug., 1890
Complete Specification Left, 6th May, 1891-Accepted, 11th July, 1891
PROVISIONAL SPECIFICATION.
Improvements in Instantaneous Steam Generators.
We, LEON SERPOLLET, and LA SOCIÉTÉ DES GENERATEURS À VAPORISATION
INSTANTANÉE (Systeme Serpollet) of 15 Rue des Halles, Paris, France, Engineers,
do hereby declare the nature of this invention to be as follows:-
This invention has reference to improvements in steam generators of the kind in
which steam is instantaneously generated in a flat capillary space within a heated
tube and relates to a new method of coiling or arranging the generator tubes, and
of staying or enveloping their spirals or branches by means of a special casting,
with the object of rendering them practically incapable of being deformed, of pro-
tecting them against too high a temperature, and to obtain massive elements that
serve to form reservoirs of heat; these elements being, capable of assuming by
moulding and casting definite interchangeable forms. The present improvements
also relate to methods of calibrating the vaporizing capillary spaces, of polishing
the surfaces of the same and preventing incrustation of the same.
In the accompanying drawings
Figs. 1 and 2 show in plan and in vertical section respectively, a tube bent in
such a manner that its spiral or bent portions are situated in one plane, with its
ends adjacent to each other, and which may be arranged to make one joint if
necessary with the inlet and outlet pipes.
The tube A is enveloped by a solid cast mass B of determined form, formed
with openings C, C for the passage of hot gases and products of combustion and
intimately attached to or soldered to the tube. The end G of the mass is formed
with notches or recesses d in which are adapted to fit, the refractory walls of the
furnace in the middle of which upon à suitable plate are arranged several
vaporizers such as A, B, connected in series that is to say one behind the other, by
means of elbows, the projection K of the one entering the circular notch or
recess K of the other. This has for its object to form a central flue, or flues, that
is or are provided with movable covers, that allow of imparting to the hot gases
and products of combustion, any desired direction, and, by means of dampers or
openings, of arresting the current, when the generation of steam is to be stopped.
The furnace may be provided at the top with a movable chimney.
The joint between the ends of the tube A and the inlet and outlet pipes, and
which may be a single or a double joint, is effected by means of bolts .J' inserted in
recesses in the cast mass, these bolts being arranged to be tightened up against
a cross piece I which bears against a union 1. The injection is always effected
through the centre.
The spiral or bent portion of a tube of the kind described may according to
another construction have thicker walls than the one shown, and be simply stayed
by means of metal keys parts or wedges cast or otherwise efficiently attached as
for instance by notches and barbs to the walls of the tube, the end portions of
which are keyed and bound with metal hoops. The keys or parts may be of cast
iron or of mild steel capable of melting at a high temperature and of becoming
welded or united to the surface of the tube A. By this construction the element
is rendered lighter in weight.
In either case, the ends of the tube A may be cut straight, as in Figs. 1 and 2,
or be made slightly flaring, or they may be rounded and their edges bent back.
The tube A may be bent in serpentine form in plan, and be arranged preferably
vertically, in order that the injection shall be effected in that portion of the tube
which is most exposed to the heat, the spirals or branches of the tube being
enveloped by a cast mass, having passages for the hot gases between the spirals.

page_text: The cast envelope or lining may further be provided along the branches of the
tube, with projecting parts or baffles the edges of which may touch the walls of
the flue.
These battle pieces are or may be "so arranged that tlie one on one side of a
branch, projects in the opposite direction to that on the next following branch, in
such a manner that the hot gases and products of combustion rise in a zig-zag
course and pass in turn under the several branches. The furnace may be pro-
vided with sight holes that are normally closed. A number of similar tubes can
be arranged adjacent to one another in the manner just described.
The very high temperature of the steam produced in such a generator, can be
measured by means of a mercury thermometer placed within a sheath, or by
means of a pressure gauge placed in connection with a closed sheath containing
water, the sheath in each case being immersed in the steam produced by the
generator.
In order to calibrate with accuracy the capillary space a band to polish its
surface the tube A, after being flattened for the greater part, is filled with a dry
and finely powdered substance, as for example sandstone and one of its ends
closed.
The tube thus prepared, is passed with the closed end foremost, between the two
smooth cylinders of a rolling mill, which expels some of the sand through the
open end, until the desired width of capillary space is obtained. The tube is then
bent to shape, and the fine sand remaining therein emptied out.
In order to prevent the capillary space thus obtained from becoming incrusted
during working, water or water containing a suitable solvent, such as hydrochloric
acid can be injected into it daily by means of a hand pump, and whilst the tube is
hot, the capillary space after this treatment being rinsed: or washed out.
Dated this 2nd day of August 1890.
COMPLETE SPECIFICATION.
Improvements in Instantaneous Steam Generators.
'I LEON SERPOLLET, and LA SOCIÉTÉ DES GENERATEURS A VAPORISATION
INSTANTANÉE (Systeme Serpollet) of 15 Rue des Halles, Paris, France, Engineers,
do hereby declare the nature of this invention and in what manner the same is
to be performed to be 'particularly ‘'d'escribed and ascertained in and by the
following statement.:-
This invention has reference to improvements in steam generators of the kind in
which steam is instantaneously, generated in a flat capillary space within a heated
tube and relates to a new method of coiling or arranging the generator tubes, and
of staying or enveloping their spirals or branches by means of a special casting,
with the object of rendering them practically. incapable of being deformed, of
protecting them against too high a temperature, and to obtain massive elements
that serve to form reservoirs of heat; these elements being capable of assuming-by
moulding and casting definite interchangeable forms. The present improvements
also relate to methods-of calibrating, the vaporizing capillary spaces, oftpolishing
the surfaces of the same, and, preventing incrustation thereof.
In the drawings left with our Provisional Specification
Fig. is a horizontal section, of one form of, tube or tubular-piece constructed
according to this invention; and
=

page_text: Fig. 6 a transverse section thereof.
Fig. 7 is a vertical section and
Fig. 8 a horizontal section on the lines Fig. 7, of a steam generator constructed
according to this invention.
In a generator according to this invention the instantaneous vaporisation of the
injected liquid is effected in the flat capillary space a of a drawn metallic tube A
which is coiled, undulating or straight and which is prevented from altering its
form by being suitably hooped or stayed or by embedding the coils or tubes in a
mass of cast metal.
Figs. 1 and 2 show a flat capillary tube A, the convolutions of which lie between
parallel planes, and having ends c c', one serving for the injection of the liquid to be
vaporised and the other serving as the outlet for the vapor. These ends are situated
close to one another.
The tube A is embedded in a casting B of cast metal through which are formed
the apertures or passages CC for hot gases and products of combustion which
passages are separated by webs. The apertures C may be of any convenient size
or form and their surfaces as well as the external periphery of the casting may be
either smooth or be furnished with projections as shown.
The casting B is provided with a projection or neck G through which pass the
two ends c c of the capillary tube and which is furnished with grooves d in which
take the edges or sides of vertical slots in the cylindrical walls M M' as shown. in
Fig. 8. Near the extremity of the tube are notches J J adapted to receive and
retain the stem and the head of the bolts JJ' the nuts of which act upon the
cross piece I and cause the same to bear upon one of the corresponding ends e
or of the tube A. Upon each of the cross pieces I is arranged one or other of
the connecting tubes TX or H. (see Figs. 7 and 8) the end of which projects into
the cross piece to which it is connected and is bent up therein bearing against a
flexible washer which in turn bears upon the interposed cap I the said cap making
a joint on the cleanly cut ends c or c¹ of the tube A. We thus obtain for joining
the several elements together a joint which is safe, easy to make, and without
projections. This joint may be arranged on the two ends cel at once when they are
adjacent to one another; similarly the two ends c c¹ instead of being cleanly cut as
in Figs. 1 and 2 may be made flaring, or rounded by meaus of a hammer, as is
shown in Figs. 3 and 4, or may even have their outer edges bent over as shewn in
Fig. 8. This hammer work may be effected before the formation of the envelope
or casting B, or afterwards when the casting is of a malleable metal as for example
ingot iron or mild steel.
As it is necessary for properly strengthening the capillary tube and for trans-
mitting the heat that this tube should be in intimate contact with the casting B,
care is taken before casting to clean or scour it carefully and if necessary it is
tinned or thinly coated with a weldable metal which will assist the union of the
parts. Intimate union is however effected when a casting B of ingot iron or mild
steel is employed by reason of the high temperature at which the same fuses, which
causes the outer skin of the capillary tube to partially melt or run and in consequence
effects an intimate welding of the tube and the metal of the casting. Mild steel in
addition to being stronger than ordinary cast iron, has furthermore the advantage
of great malleability; it enables vaporisers to be made of comparative lightness
and withstands changes of temperature in the furnace, better than cast iron and
protects the embedded tube to a greater extent.
The envelope or casting B allows of giving to the vaporising elements forms
which being obtained by moulding, allow of easy erection of the generators and of
interchangeability of the parts. It constitutes a large and economical reservoir of

page_text: heat. Independently of the lateral grooves dd, and of the notches J cast in the
projection or neck G, a circular projection K is formed at the lower part of the
envelope or casting B while at the upper part an annular groove or channel K¹ of
the same diameter is formed. The projection K of one element is adapted to enter
the groove K of the next lower clement the part of the said groove not occupied
by the said projection being filled with fine dry sand. This projection K and the
corresponding groove K' may be employed whether the envelope or casting B is of
circular, rectangular, or other form.
A number of vaporising elements may thus be arranged together and coupled up in
series, that is to say connected together as shown in Figs. 7 and 8 and forming distinct
groups, cach being fed and operating separately. A number of such groups may
be connected to form a battery, thus constituting an arrangement of great vaporising
power, whether the tubes be coiled in spiral form, or bent in flat serpentine form,
or be straight.
The tube A need not necessarily be completely enveloped by the casting of ingot
iron, or mild steel, but in such a case the walls of the tube A. should be thicker. It
will be seen that in Fig. 3 the end portions c c¹ of the tube are stayed apart, and
connected to the adjacent spiral by hoops e which may to a slight extent be let
into the top and bottom portion of the tube. The other coils are similarly stayed
and held together by stays or webs formed of metal cast after the tube has been
placed in the sand. In the case where the tube is embedded in a thin envelope of
cast metal, the sides of the tube may be made thinner than otherwise, thin stays or
webs of less width than the tube being employed as shown in Figs. 5 and 6 to
give additional strength.
In order that these stays or webs shall not become displaced where they bear
against the sides of the tube, barbs or projections (Fig. 4) are raised by means of
a chisel on the side walls of the tube A and of the hoop e these barbs projecting
in opposite directions as shown. The points of these barbs melt when in contact
with the molten cast metal and become welded with this metal,
By thus hooping, staying, or enveloping, the coiled tubes shown in Figs. 12
and 3, or the bent or serpentine tubes shown in Figs. 5 and 6, there can be obtained
steam generators which are more or less light and are sufficiently strong to prevent
the deformation of the capillary space a b.
The vaporising tubes bent in flat serpentine form as shown in Figs. 5 and 6, can
be arranged horizontally one above the other, as in the case of the vaporising tubes
of the forms shown in Figs. 1 and 2, and in Figs. 3 and 4. In order however to
obtain the best results it is preferred to inject the feed water or liquid into the
hottest coil, that is, the central or lower one, and to cause the hot gases to travel
in the same direction as the current of water and steam, and to arrange the tubes,
whether they be single or in two parts arranged symmetrically side by side, or con-
nected together in series, so as to operate vertically. Furthermore in order to
give to the ascending gases a zig-zag course, baffles D D and D' D¹ are cast on the
straight portion of the envelope B, the baffles on successive folds or portions of the
envelope being arranged alternately on the left and right hand sides of the tube as
shown more clearly in Fig. 6. These battles are of any convenient form and bear
at their ends laterally against the walls of the furnace which latter may be of
rectangular, elliptical or circular form, in such a manner that the gases passing
through the openings C C circulate from one side to the other of each branch of
the tube and under the baffles D D' in the direction of the arrows shown in
Fig. 6.
Figs. 7 and 8 illustrate the construction of a steam generator formed by con-
necting in series three spiral vaporising elements, the tubes A of which are
embedded each in its cast metal block or envelope B. The arrows indicate the
direction of the hot gases and products of combustion which are caused to diverge
from the centre by the refractory plug L which can be removed, as also can the top
of the furnace and the cover Q for inspecting, cleaning, or taking apart the
vaporisers. The gases are then caused to descend by the refractory cylindrical

page_text: casing M which surrounds the vaporisers, and then pass between the edge of the
wall M and the plate P and reascend through the annular space N between the
wall M and the outer wall M'.
This outer wall M' is also of refractory material, and is surrounded at a short
distance by the outer sheet metal casing at the lower part of which are provided
suitable openings S each closed by a plug S which serve to diminish the flow of the
hot gases when the operation of the boiler is stopped. The supporting plate P, on
the inner edge of which the lowermost element is carried, supports, by means of
projections i, a circular metallic support with groove upon which rests the
wall M. The said plate also carries the wall M³.
On the wall M is a channelled piece K in the upper groove of which rests the
edge of the refractory cover Q, which may be removed by means of two rings ll',
when it is desired to inspect or clean out the inner vaporisers.
The wall M' is also provided with a recessed ring ' as shown having a flange
or projection surrounding the upper edge of M' and which ring has formed in the
upper part thereof, a groove in which, as in the others, is placed fine sand to make
joints. The chimney R of sheet metal rests with its edge in the said groove, and
the casing
in rests on the upper edge of the casing of the furnace.
The pieces kk' may be fixed or removable; in the former case they are cut
away to allow of the passage of the projections or necks g g of the vaporisers.
The walls M M are formed of moulded pieces of refractory material. The outer
casing bears, at one part against projections formed on the ends G of the
vaporisers.
The liquid injected enters by the tube T, (Fig. 7) into the inner coil of the lower
tube, which is the most highly heated it becomes vaporised therein and the steam
generated passes through the connecting elbow H provided with a cock U, into
the inner coil of the second tube, and passes thence through the elbow H', which
is also provided with a cock U', into the inner coil of the third vaporising
clement, and so on if there are more than three elements. On the exit pipe X
is another pipe o provided with a cock U", connected to which is a discharge tube
for cleaning purposes. To the flange V of the tube X is attached the apparatus
for indicating the temperature of the vapor which arrives at this point in a some-
what superheated state.
This apparatus is contained in the box or casing X traversed by the steam and
comprises a tube p screwed tightly into the casing and closed at its lower end.
Upon this tube may be screwed a union with two ways, one to communicate with
a pressure gauge, the other intended to receive a screw plug, so that the tube can
be closed hermetically when desired.
By placing mercury in the tube p and plunging a mercury thermometer therein,
this instrument will indicate, say up to 350° C., the temperature of the steam which
passes through the casing X. By placing water in the said tube, screwing
thereon the aforesaid union, and placing it in communication with a pressure gauge,
there can be ascertained the temperature of the steam passing through the casing
by observing the pressure indicated by the said pressure gauge. The two indica-
tions may be checked by means of two separate tubes, one for mercury, the other
for water.
There now remains to be explained the mode of preparing and of accurately
calibrating the capillary space a 6 within the tube A, whilst at the same time
polishing the surfaces of the same, and also the mode of preventing obstruction of
the same by calcareous or other deposits. The tube having been brought to a
sufficient degree of flatness, and the space a b having still an appreciable width, say
of about 2, it is closed at one end and filled with fine dry sifted sand, or other
similar and suitable material. The tube thus filled is passed several times in
succession between suitable smooth rolls, its closed end being inserted first between
the rolls at each passage. Each passage through the rolls causes the expulsion of
a certain quantity of the sand at the open end, the rolling being continued until

page_text: the tube arrives at the required degree of flatness and the capillary space is of the
desired width. The sand or other material after the tube has been coiled or
bent if it is not to remain straight, is then extracted or shaken out when it will
be found that the internal surfaces will have become quite smooth and polished.
In order to prevent obstruction of the capillary space of the vaporising tube or
tubes, the vaporizer when very hot, is fed by means of a hand force pump, a free
passage towards the feeding tank being opened to the generated vapor by a discharge
pipe. The great speed acquired by the current, is sufficient to carry away any
incipient deposit. However in such cases where the deposit is already so strongly
adherent, that the mere injection of water is not sufficient to remove it, then by
means of an arrangement of cocks with which the force pump is provided, water
containing some dissolving agent such for example as hydrochloric acid, is drawn
from a small reservoir for this purpose, and after one of the plugs U U is opened,
the injection is continued, the dissolving liquid passing out by the opening from
which the said plug is removed. The injection is continued only for a few seconds,
and the tube is then washed out by an injection of pure water. In most cases it
will suffice to clean the boiler in the manner described once a day.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed 1. declare that what
I claim is :-
1. In an instantaneous steam generator of the kind herein referred to, a capillary
tube the spirals, folds or serpentine portions of which are embedded in a heavy
casting B or are stayed or held apart by webs f of ingot iron or mild steel which
melts at a high temperature and becomes welded or intimately connected with
the surface of the tube substantially as hereinbefore described for the purposes
specified.
C
2. In an instantaneous steam generator of the kind in which steam is generated
in a flat capillary space a ba plane spiral vaporizing tube embedded in a mass B
of cast metal intimately united to the surfaces of the tube by means of barbs
and having its ends ce brought near to each other, the said mass being formed
with holes or passages CC, and terminating in an end G furnished with grooves d, d',
and notches or recesses JJ; and being provided with a lower projection K and an
upper corresponding groove or recess K substantially as hereinbefore described
with reference to and shown in Figs. 1 and 2.
3. In an instantaneous steam generator of the kind referred to, a tube A having
thickened walls, and whose spirals retained at the ends by the hoop e, are stayed
by means of keys or webs cast and united to the walls by means of retaining
notches or locking barbs y substantially as hereinbefore described with reference to
Figs. 3 and 4 of the accompanying drawings.
4. In an instantaneous steam generator of the kind referred to, a tube having a
joint formed upon the end c or e, or upon both when they are adjacent, by means of
notches or recesses JJ, bolts JJ, the cross piece I the upturned edge of the
tube T and the cap 1', substantially as hereinbefore described.
5. In an instantaneous steam generator of the kind referred to, the arrangement
in series and in the same furnace, of a number of tubes with capillary spaces
therein, the tubes being connected by means of the joint specified in Claim 4
together with the tube T, elbows H, H and pipe X, substantially as hereinbefore
described.
6. The construction of instantaneous steam generators substantially as hercin-
before described with reference to and shown in Figs. 7 and 8 of the accompanying
drawings, and for the purposes specified.
7. In an instantaneous steam generator of the kind referred to, a steam generating
capillary tube bent into a plane serpentine form, and provided with alternately
arranged baffles D D' cast in one with the envelope B of the said tube and hearing
against the walls of the furnace due substantially as hercinbefore described with
reference to Figs. 5 and 6.

page_text: 8. In an instantaneous steam generator of the kind referred to, apparatus for
indicating the temperature of the steam generated therein, consisting of a box X
provided with a tube or case p, containing either mercury into which a thermometer
can be freely immersed, or water the steam produced from which acts upon a pressure
gauge, substantially as hereinbefore described.
9. The herein described method of calibrating the capillary space a of a steam
generating tube of the kind herein referred to, and of polishing the walls of the
same, by subjecting the tube A whilst it is filled with suitable finely pulverized
material such as sandstone to a rolling operation as set forth.
10. In an instantaneous steam generator of the kind herein referred to, cleaning
or removing incrustation from the capillary space thereof, by injecting water or
water containing a suitable solvent such as hydrochloric acid into one end of said
tube, the other end of which is then opened for the free exit of steam, substantially
as hereinbefore described.
Dated this 4th day of May 1891
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.