Improvements in Tubes for use in all kinds of Steam Generators and other Apparatus.
Year: 1893

page_text: Date of Application, 12th Apr., 1893-Accepted, 27th May,
1893
Improvements in Tubes for use in all kinds of Steam Generators
and other Apparatus.
I, SANTIAGO BIOSCA of 3, Calle del Carmen, Barcelona, Spain, Architect, 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 tubes for use in all kinds of steam generators and other
apparatus and has for its object the provision of a large amount of heating surface
in a minimum space.
The rapid and economical generation of steam has always been one of the
problems which have commanded much of the attention of the industrial world.
In the presence of the difficulty of finding another agent of motive force which
might advantageously replace so powerful an element, also that fuel is day by day
becoming more scarce, profiting by the immense improvements discovered in
metallurgy, all manufacturers have made great efforts to perfect the means utilised
to produce or generate this element of force.
It will suffice to glance upon the primitive types of boilers and to compare them
with the multitude of generators which are now in use, in order to convince oneself
of the decisive tendency which has existed to search in a certain direction in order
to obtain the greatest heating surface in the smallest space for the purpose of
obtaining the greatest rapidity in the production of steam with the smallest
expenditure of fuel, at the same time reducing the dangers of explosion.
If we review all the apparatus of this kind that was exhibited at the Paris
International Exhibition of 1889, we note that nearly all those enormous
receptacles, half or completely filled with water and exposed to the direct action of
the flames, which were formerly employed, and into which the sudden introduction
of a simple jet of cold water could occasion the most terrible accidents, have been
replaced by an aggregation of receptacles of much smaller dimensions disposed in
such a way that while diminishing the probabilities of explosion, they offer very
important advantages on account of the rapidity and economy in the generation of
the steam. We know however that boilers exist having a large water space that
have given and are giving very excellent results after long terms of service.
know also that there is some exaggeration in terming multitubular boilers with
small water space or which are rapid steam producers inexplosible; this has led to
the perfecting of old boilers by adapting some organs of the latter, which constitute
the boilers termed semi-tubular.
We
This being proved, we shall remark that the helical fluted tubes, of which this
invention consists, ought not to be considered as perfecting either one or other of
the before mentioned systems separately, as they can be applied indiscriminately to
all kinds of boilers at present known. They can be employed in the old fashioned
boiler having a large water space or the new boiler of the Fontaine type, or the
cross boilers of Archambault type, or to form the series of inclined tubular boilers
of the Belleville, De Naeyer, Babcock and Willcox, Root types and their
innumerable varieties; or to be substitutes for the hanging conical tubes of Dulac's
system or the radiating tubes of the Dion Bouton and Trepardoux systems or Field
tubes, conical Galloway tubes, etc.
Our helical fluted tubes are equally applicable as internal furnace tubes as for
tubes for the passage of gases of combustion employed in locomotive and marine
engines, in a word they can be employed very advantageously in all the industrial
applications where a large surface is required in a small space, for example, in

page_text: "
replacing the arched tubes employed in certain fire engine boilers, in the con-
struction of spiral cooling coils of large distilleries, in the construction of condensers
used largely in ice manufacture and in other industries. It appears then that
boiler makers in general and persons who use this kind of apparatus will appreciate
the value my invention, as its simplicity is very evident, because in principle it
consists simply in puckering so to speak the periphery or exterior of the cylindrical
or conical tube, small or great, in such a manner that the folds or wrinkles form a
continuous flute or spiral groove reducing by half, the original length of the tube,
in other words that with the same length of tube and the same diameter double the
surface is obtained.
In order to better understand the method of construction of my helical fluted
tubes, I will describe them in relation to the accompanying drawings, in which I
represent two specimens as examples, which I think are sufficient for competent
persons to obtain a comprehensible idea of the distinctive features of my invention
and of the advantages to be derived by its application in various ways.
Figure is a diagram which shows the amount of surface obtainable by bending
more or less the sides of a cylindrical tube.
A. B. represents the straight generating line of the length given to the tube.
If to this generating line one adds the curves indicated in the line C. D, that is
to say slight undulations formed by arcs of circles disposed alternately and tan-
gentially to one another there will be an increase of length represented by the
difference between the chord and the arc, which in this case
only 0.11 this is to

page_text: We have seen by the 4th case that one can carry this augmentation much
further, nevertheless it is evident that the practical difficulties will be greater in
proportion to the ratio which exists between the chord of the arc and the tangent
element. I only record these cases to illustrate, the numerous varieties to which
my system is applicable, I can in fact, vary the proportions of the generating line
in form and in size according to the diameter, that is to say, I can construct a tube
of large diameter with a small undulation or one proportional to the diameter.
With the undulations shown in the drawing especially those in the 2nd and
3rd cases it will be readily understood that with such generating lines cylindrical
or conical fluted tubes of large or small diameter can be constructed of which the
flutes may be normal to the axis of the cylinder or of the cone, but the tubes thus
obtained although they would fulfil the desired condition of augmentation of surface
in the manner hereinbefore described, would not realise the object that I have put
forward as to the circulation of the gases, of the vapours, or of the liquids, under
bad conditions, rendering impossible the cleaning away and extract of deposits
which would collect in all the folds. Since, the absolute necessity of our generating
lines is that at the same time that they turn round the straight cylinder of which
the body is the mean circle of the tube, they move themselves forward a certain
distance, forming a helix or better expressed a true screw thread of which the bead
is a double hook in form of S, it is for this reason that I designate my tubes under
the title of helical fluted tubes or in form of Salomon screws or round threads.
The circulation of water or other liquid, of steam or gases is thus perfectly
assured without any fear that the least quantity of these fluids will stop in the
undulations; the interior cleaning is much easier than that of an ordinary straight
tube, as it is only necessary to insert a ramrod brush or other convenient tool in
the tube, giving it a rotating movement to separate the deposits which have been
formed on the interior and eject them at the opposite end of the tube; besides the
deposits will be formed with difficulty, because the circulation will be much more
rapid than exists in ordinary tubes, because beyond the normal inclination of the
tubes, there is added that of the inclined plane which constitutes the path of my
screw.
Figure 2 represents partly in elevation and partly in vertical section a tube
according to my system constructed in accordance with the 3rd case and which we
term narrow throat because the culminating points of the undulation at the interior,
are nearly coincident with the mathematical axis of the tube. It is obvious from
the drawing that one can construct tubes of any desired size, also that without
varying the diameter of the tube the smallest undulation can be applied. In that
case one will always have
GH = 2A B
that is to say a surface of screw, double that of the original cylinder.
Figure 3 represents partly in vertical section and partly in elevation another
specimen of the same form of tube, of the same construction as that indicated in
the 3rd case and with the same undulations as the tube represented in Figure 2 but
made on a tube of greater diameter presenting a larger throat.
That being proved it is very easy to imagine other examples which it will be
useless to represent; it is understood that the diameter of these tubes can be
increased indefinitely the undulation remaining the same, or even the diameter
and undulation can be varied proportionately without changing the essential
condition
GH 2A. B.
=
Having described the essential system of my tubes, it only remains for me to
say that they can be made of any material and by the most convenient process,
according to the use they are to be put to, one may employ wrought iron, rolled or
malleable, cast iron, steel, copper, brass and all other metals, or convenient metallic
alloys, and the tubes will always have compared to ordinary straight tubes a greater
resistance, and give greater facility and certainty in cleaning and will especially

page_text: present a marked augmentation of surface, without any variation of volume and in
consequence in their application to steam boilers, besides the diminution or obviation
of dangers of explosion, they will give a very large increase of power as well as
great economy in the consumption of fuel.
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:
:-
Tubes of helical fluted form for use in steam boilers and other apparatus, substan-
tially as described and illustrated in the accompanying drawings.
Dated this 12th day of April 1893.
FELL & WILDING,
Agents for the Applicant.