Improvements in Instantaneous Water-tube Steam Generators.
Year: 1899

page_text: Date of Application, 8th July, 1899-Accepted, 21st Oct., 1899
,DIUITATUT ענענע טט
Improvements in Instantaneous Water-tube Steam Generators.
I, ALFRED PETIT, of 4, Rue Hanneloup, Angers (Départment de Maine et Loire),
in the Republic of France, Surgeon Dentist, 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:—
My invention relates to an instantaneous water-tube steam generator in which all
the sections or elements are interchangeable and can be taken out and cleaned or
replaced even while the boiler is at full heat, which characteristic is of the highest
importance in the application of steam boilers to motor cars.
The principle of my invention consists in fixing the connecting pieces of the
successive elements on the tubes open at both ends which constitute the casing
of these elements by means of cap nuts or nuts having a shoulder, arranged
outside the boiler and always accessible from the outside; these nuts being
unscrewed any element can be reached and cleaned without waiting for the boiler
to become cool and if required it can be replaced without loss of time.
The principal practical difficulty in the application of my invention I found to
consist in obtaining tightness of the joints which is difficult with joints which
must be easily undone whilst at the same time being subjected to high pressures
and to sudden variations of temperature. The various forms hereinafter described
of the elements of the boiler according to my invention are devised for realising
this practical condition, at the same time providing facility for removing and
replacing the parts whilst hot.
In the drawings,
Figure 1 is a partial front elevation of a number of boiler tubes.
Figure 2 is a section on line 2-2 of Figure 1.
Figuro 3 is a plan of Figure 1.
Figure 4 is a transverse section of a tube.
Figures 5, 6 and 7 represent respectively a front view, a side view and a plan of
a boiler constructed according to my invention.
Figure 8 illustrates the grouping of three consecutive elements of a second
typo of thick tube.
Figure 9 is a transverse section corresponding to Figure 8.
Figures 10 and 11 illustrate a third modification.
Figure 12 illustrates a fourth modification of the element.
Figures 13 and 14 are respectively an elevation and a section of one of the
communication boxes uniting the elements.
Figures 15 and 16 are respectively a front elevation and a side elevation of a.
complete boiler.
Figure 17 is a view of a detail.
The elementary tubes a which constitute the boiler represented in Figures 1
to 7 are connected in serpentine fashion by means of small tubes & curved to a
horse-shoo shape and adapted to their ends.
These tubes of cold drawn steel without solder are star shaped in section, aa
illustrated in Figure 4; through ribs on each tube a I form a helicoidal groove
extending from one end to the other of the tube and which divides these ribs
[Price 8d.]
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page_text: into numerous projections which together form a very large heating surface.
With the same object the tubes a may have a polygonal section or be provided
with ribs, wings or the like.
The horse-shoe shaped junction tubes 6 are also of cold drawn steel without
Bolder; they are relatively thin and narrow with respect to the radius of curvature
so that they possess great flexibility and exert no injurious strains upon the
joints notwithstanding any very unequal expansion of the tubes a. Cap-nuts o
having their bearing surface on rings d fixed to the tubes b and screwing over
the end of the tubes a allow of conveniently connecting these tubes together.
The adjacent ends of the tube a and of the ring d are formed with conical
surfaces which, when the nuts c are tightened, form a perfect joint.
The tubes a and b and the rings d being all made of the same metal and united
Bs just described, can support the greatest changes of temperature without the
absolute tightness of their joint decreasing in the slightest..
Within each tube & are loosely introduced copper tubes s of polygonal section,
equare for example, which are each closed at both ends. The main object of these
tubes is to reduce the section of the passage for the water with a view to its
instantaneous conversion into steam. The division of the tubes e into rather short
sections always affords great facility for withdrawing them from the tubes a if
the latter become bent or misshapen under the action of the fire.
The employment of copper also allows of withdrawing the tubes a by reason
of the malleability of this metal; copper is besides chosen for the reason that it
constitutes with the steel an electro generating group preventing the formation or
adherence of deposits in the interior of the elements.
A boiler is generally formed of several series, each consisting of a certain number
of tubes say, for example, 13 tubes, as illustrated in the drawing.
The tubes a of a series are supported at their ends by, junction pieces, each
comprising two rectangular plates f, f united by tie bars g and the space between
which is filled with a suitable non-conducting material such as a mixture of
asbestos and refractory clay. The holes in the plates f, f are made of the same
star shape as the tubes a in order that the latter shall not turn when the nuts c
are tightened. These holes are arranged quincuncially and in such a manner
that when several series are superposed, as shewn in Figure 5, all the connections b
are interchangeable.
In each series the two junction pieces f, f at front and rear are connected
together by tie bars i bolted at their two ends.
When several series are superposed they can be mounted in sections, that is
to say, the water enters at (Figures 5, 6 and 7) through the first tube of the
lowermost series and the steam leaves through the last tube y of the uppermost series;
the series can also be mounted parallelwise, that is to say, the first tubes of the
different series communicate with a feed pipe whilst the last tube of each series
is connected to a common steam collector; or the boiler may comprise several
groups connected parallelwise, each of them being formed of several series in
sections.
The sides of the boiler parallel with the direction of the tubes are closed by
sliding or folding doors k lined with a non-conducting material; these doors allow
of conveniently reaching and cleaning the tubes a. The latter can be heated by any
suitable furnace with coal, petroleum or the like such as a furnace provided with
Longuemaro burners for example.
The gases from the combustion escape through a chimney, m after having
circulated around the tubes a.
The differences of construction of the elements represented as types of modifica-
tions in Figures 8 to 16 result from the varying dimensions that these elements
may have according to the power of the boilers.
Figures 8 and 9 represent an element with a thick tube, the walls of which are f
ten millimeters or more in thickness. The tube a of cold drawn steel without
solder is at each end reduced in diameter for a certain length m, n and is screw-

page_text: threaded for a portion n, o of this length. Between the shoulder m and the
commencement o of the screw-thread, a groove p is made which is traversed at
one or more points of its periphery with holes g directed towards the axis of the
tube.
Into the interior of the tube a is passed a polygonal rod e, square, pentagonal,"
hexagonal, etc., according to the diameter of the tube and adapted to be divided into
several sections. This rod touches the tube at its angles, sliding with very slight
friction, and leaves between its sides and those of the tube a semi-capillary space.
of about half a millimeter to two millimeters in width.
Instead of a solid rod I can employ one or several hollow rods closed at both
ends, which allow of lightening the boiler while affording the same results.
Each tube is united to the following one by means of a communication box r
(Figures 13 and 14), consisting of a steel block made with two circular aper-
tures s, s, directed transversely to its thickness and of a diameter sufficient to allow
the threaded parts of the tubes a to pass freely. These two apertures are provided
inside with a groove t corresponding to the groove p of the tubes a and outside
with two recessos designed to receive asbestos washers v, v forming tight joints.
A passage z made through the axis of the block between the grooves t, t places
tho two apertures s, & in communication. The fixing of the box r upon each of
the tubes a is effected by means of a cap-nut e screwed over the end of the tube,
the box r being gripped between the shoulder m of the tube and the base of the
nut, and two asbestos washers v being interposed.
When two tubes a, a are thus mounted on a box they are placed in communica-
tion through the holes g, the space comprised between the grooves p and t, and
the passagoz.
The interior rod e is of the same length as the tubo a and is free to slide when
ono of the cap-nuts c screwed to the ends of the tube is removed.
In Figures 10 and 11 a modification is illustrated in which a thin tube is.
employed; the thread n, o designed to receive the nut is not made upon the .
tubo a but upon the interior rode; it is the same with the groove p facilitating
the passage of the steam from one element to the next. The tube a bears.
directly with its free end against the box r and has no shoulder as in the preceding
case.
In a fourth modification represented in Figure 12 the thread n, o is made in .
the thickness of the tube but it is interior instead of being exterior and the cap-
nuts are replaced by screw-threaded plugs c, the stem of which passes through
the communication box and is screwed into the tube a; an annular groove p made
on the plug opposite the groove of the box communicates with the interior of
the tube through the medium of a narrow passage 1 and holes 2 made in the
bottom of the groove p. The box is of the same form as that hereinbefore
referred to and is similarly provided with two asbestos washers v.
.
In a boiler constructed according to my invention one of the elements at least
should be provided with a pipe or nozzle for the inlet of the water and another
pipe or nozzle for the outlet of the steam; this nozzle shewn at 3 in Figure 8 is
screwed or brazed into a nut c.
These
Figures 15 and 16 shew, by way of example, the general arrangement of a
boiler composed of elements united by means of communication boxes r.
elements are placed in horizontal rows I, II, III superposed in suitable numbers,
the last element to the left of the row I being connected to the last element at the
left of the row II, that at the right of the row II being connected to that at the right
of the row III and so on. In order to utilise the heat of the furnace to the fullest
extent and, above all, for the purpose of employing a unique type of communica-
tion boxes r, I preferably arrange the tubes quincuncially as shown in Figure 15.
The elements are supported at their ends by cast iron or steel plates which I
make by preference with double walls having an interior lining of refractory
material; the holes made in these plates are of a diameter greater than that of
the tubes to allow the said tubes to be easily withdrawn in cases where they

page_text: may have become misshapen or expanded at any part; the space between each
tube and the sides of the hole which receives it can be filled by means of a movable
ring 4 (Figure 17) of the required thickness and which can always be removed
without difficulty through the exterior.
While the boiler is at work during which it is heated to a temperature of at
least 2500, the wator is injected by a pump at one of the ends of the first tube
of the lower row 1, and the steam produced instantly leaves through the end of
the last uppermost tube of the boiler.
If one of the elements should burst, which would not give rise to any danger by
reason of the excessively small interior volume of the boiler, it is only necessary
in order to remedy the accident, after having closed the cocks placed on the water
and steam pipes, to unscrew one of the nuts e corresponding to the damaged
clement, as well as the nut corresponding to the adjacent tube on the communica-
tion box placed at the opposite side; the tube can then be withdrawn from the
side of this box and immediately replaced even when hot; in this case the box r
remaining fixed to the tube in question should be gripped with suitable pincers.
As all the elements of the same nature are interchangeable the replacing of au
element can be effected without any loss of time.
For cleaning it is only necessary to unscrew the nuts e and to withdraw the
rode of the tube to be cleaned; the tube, access to which is thus rendered free,
can be cleaned while hot.
Figure 8 shews in detail an arrangement which allows of cleaning the tubes
without stopping the working of the boiler to any appreciable extent and which
can be removed with no more difficulty than the nuts when the tubes a are to bo
reached or taken out. It consists of a screw-threaded rod or pin 5 having a
pointed end and operated by means of a handle or a handwheel 6. This rod is
screwed into the nut 7 forming a cap or stirrup; its point is guided in front of an
aperture 8 made in the centre of the nut 7 and which allows of effecting com-
munication between the interior of the element a and the atmosphere through the
lateral apertures 9 wlien the point is withdrawn from its seat. I can provide all
the tubes of the lower row of the boiler with similar valves, there being a greater
tendency for deposits to form in them; each of the said valves is opened from time
to time whilst the boiler is at work, and the steam, escaping through the
apertures 9 carries the pulverulent deposits along with it.
The operation of getting at the elements only requires a stoppage of a few
minutes and can be effected without lowering the fire so that the boiler is put in
action again immediately.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. In an instantaneous water-tube steam generator an element comprising a
straight tube open at both ends, one or more rods of polygonal or star shaped
section located within the said tube and a connecting tube of small diameter
curved into a horse shoe shape and having at its ends two conical joint rings
against which abut nuts having shoulders and each screwing on to the end of one
of the straight tubes to be connected, substantially as set forth.
2. In a boiler constructed according to Claim 1 the application to the interior
of the tubes or elements of rods of polygonal section divided into short lengths
in order to facilitate the withdrawal of the said rods from the tubes in case of
accident, substantially as set forth.
3. In a steam boiler constructed according to Claim 1 the arrangement of
double plates lined with refractory material and provided with star shaped holes
preventing the tubes or elements from turning when the connecting nuts are
turned, substantially as set forth.
4. In a steam boiler constructed according to Claim 1, a connecting arrangement
for uniting two tubes or elements comprising a communication box passed over

page_text: the ends of the tubes opposite lateral apertures in the said tubes and cap-nuts
screwed over the said tubes and keeping the said box in position, substantially as
set: forth.
6. In a steam boiler constructed according to Claim 1 a connecting arrangement
for uniting two tubes or elements comprising a communication box arranged
against the ends of the tubes and cap-nuts screwed over rods which occupy the whole
length of the tubes and which have recesses opposite the apertures in the
communication box, substantially as set forth.
6. In a steam boiler constructed according to Claim 1, a nut for securing the
communication boxes upon the tubes or elements comprising a head provided
with a pointed serew-threaded rod or pin serving as a discharge valve for the
automatic and instantaneous cleaning of the elements, substantially as set forth.
Dated the 8th day of July 1899.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.