Year: 1896

page_text: I, ETIENNE LAGOSSE, of 7, Rue Maubeuge, Paris, in the Republic of France, Civil
Engineer, do hereby declare the nature of this invention to be as follows:-
My invention relates to a steam boiler of the semi-multitubular type and designed
more particularly for use as a marine boiler and has for its object to provide a boiler
which shall occupy a smaller space, shall be lighter and effect a larger saving in fuel
than such boilers as hitherto constructed.
According to my invention I provide two semi-multitubular generators placed one
above the other and each formed of a boiler, properly so called, connected, by bundles
or clusters of inclined water tubes which are straight and of the same length, to two
heating tubes symmetrically arranged and in communication respectively with one
another, that is to say, those of the lower generator in communication with those of
the upper generator.
The lower generator which as described comprises a boiler proper, symmetrical
heating tubes and two bundles of inclined water tubes is arranged directly underneath
the upper generator which also comprises a boiler proper, symmetrical tubes and two
bundles of inclined water tubes. The water tubes of the lower sets have a
comparatively large diameter and leave large spaces or passages between them for the
circulation of the gases from the furnace, whilst the water tubes of the upper bundles
have a similar diameter and leave between them smaller spaces or passages.
The heating tubes of the lower generator are in communication with the heating
tubes arranged above them and this communication is effected by means of vertical
tubes or passages the number of which is suitably determined.
The boilers proper are in communication with one another by means of large tubes
which project more or less into the upper boiler and which are fitted at their lower
ends, in groups of a suitable number, into cast steel sockets which are bolted or
riveted to the lower boiler and which together form a longitudinal division between
the boilers.
Above the upper boiler a steam collector is arranged which collector communicates
with the said boiler by tubes.
My boiler is arranged symmetrically with respect to its vertical axis; above the
ash-pit the grate occupies the whole of the space between straight feet of refractory
material which cover the feet or supports at the front and back of the boiler. The
heating tubes of the lower generator are placed the one to the right and the other to
the left of the furnace a little above the grate and in such a manner as to enable the
gases of combustion to act upon as large a surface as possible. The heating tubes,
the boilers and the steam collector are suitably supported and the whole is enclosed
in a double jacket or envelope of metal provided with a material which is a
non-conductor of heat.
The tubes of the bundles, being all of the same length, are inserted in tubular
parallel plates which form part of the heating tubes and of the boilers. The tubes
determine by their length the diameters of the boilers as these tubes, to be placed in
position or removed, are passed through the said boilers. In the same manner the

page_text: passages or tubes, which effect communication between the heating tubes of one
generator and those of the other, determine the diameters of the heating tubes.
All the doors necessary for feeding the furnace and for repairs and cleaning or for
other purposes, are arranged in the front of the boiler so as to enable the rear end of
the same to be placed against a wall or the like if necessary so as to economize the
space occupied by the boiler.
The circulation of the water takes place normally. The heat radiating from the
furnace acts directly on the lower heating tubes the lower boiler and the lower set of
tubes. The steam produced carries with it the water in the lower heating tubes into
the lower sets of tubes, then into the lower boiler from which they pass to the upper
boiler. There the steam formed separates from the water and passes to the collector
whilst the water returns through the upper sets of tubes, the upper heating tubes and
the passages to the lower heating tubes.
The gases of combustion rise, whilst burning, into the chamber formed by the lower
heating tubes the lower bundles of large water tubes and the lower boiler, which
chamber has the form of a reversed V. These gases then divide themselves into two
diverging currents, pass through the bundles whilst acting energetically on the tubes
and spread into the spaces below the upper generator where they finish burning;
then they act upon the upper water tubes and the upper boiler. As the spaces which
separate the upper tubes are relatively narrow and as the diameter of these tubes is
small in comparison with the diameter of the lower tubes, the circulation of the gases
is retarded whereby they are forced to impart to the water the greater part of their
heat which they have preserved up till then.
After having passed through the tubular bundles of the upper generator one of the
gaseous currents comes in contact with the upper portion of the boiler of this
generator and with the underside of the steam collector before passing to the
chimney; the other gaseous current passes directly from the corresponding tubular
bundle to the chimney.
Baffle plates or screens may be placed in the path of the gases to regulate the
circulation and each of the generators can be formed if desired of a boiler and of a
single heating tube with a single bundle of water tubes.
My marine boilers may be arranged in groups of any number by connecting them
one to the other laterally or by their rear ends, by placing them end to end, or in any
other suitable manner.
Improvements in Steam-Boilers..
I, ETIENNE LAGOSSE, formerly of 7, Rue Maubeuge, now of 69, Rue. Hauteville 40
Paris, in the Republic of France, Civil Engineer, 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 a steam boiler of the semi-multitubular type and designed
more particularly for use as a marine boiler and has for its object to provide à boiler 45
which shall occupy a smaller space, shall be lighter and shall effect a larger saving of
fuel than such boilers as hitherto constructed.
According to my invention I provide two independent generators each formed of a
cylindrical chamber or boiler, properly so called connected by inclined straight tubes

page_text: arranged in pairs in the same vertical plane; the water-tubes of the lower generator
which tubes are placed near the furnace, are arranged with spaces between them and
are of comparatively large diameter whilst the tubes of the upper generator which
are placed near the chimney are arranged close together and are of relatively small
diameter.
With this construction the boiler is very compact because it is reduced in breadth
and depth; its efficiency is superior to that of ordinary marine boilers in consequence
of the rapid and methodical circulation of the water and of the efficient cooling of
the furnace gases by their passage through the different bundles or clusters of tubes.
The boiler can be attended to repaired and cleaned both inside and outside with
great facility as hereinafter described.
In the accompanying drawing,
Figure 1 is a sectional elevation of a marine boiler made according to my
invention:
Figure 2 is a longitudinal section on the line 1 2 3 4 Figure 1:
Figure 3 is a partial section on the line 5-6 Figure 1:
The boiler consists of two generators connected together and superposed, each
generator comprising a boiler properly so called and two heating-tubes the whole
being arranged upon a single bed of masonry covered by a common non-conducting
envelope and provided with a single steam collector.
The heating-tubes are connected to their respective boilers, which are arranged
above them, by inclined water-tubes of equal length. The tube clusters c, c which
connect the lower heating-tubes A, A¹ to the boiler B of the first generator 'are
composed of tubes of comparatively large diameter and having between them wide
passages for the gases of combustion whilst the tube clusters d, d connecting the
upper heating-tubes E, E¹ to the body of the boiler F of the second generator are
composed of tubes of comparatively small diameter and arranged very close together
in order to sufficiently cool the gases before their entrance into the chimney.
The boilers properly so called B and F are of known construction and their diameter
is determined by the length of the water-tubes employed which are fitted in position
and removed by being passed through the said boilers. Towards its lower part and
opposite the heating-tubes each of these boilers is provided with tube-plates b, b or f,f
forming between them a space of the shape of a V somewhat opened out (Figure 1).
The heating-tubes A, A¹ and E, E are similarly provided with tube-plates b, b1
orf, to correspond with the plane portions of their respective boilers, the said.
plates being secured to their tubes parallel to the corresponding plates b and f.
On referring to Figure 1 of the drawing it will be seen that the boiler is symmetrical
with respect to its median vertical plane.
Above the ash-pit h the grate G comprising three lengths of fire-bars occupies the
whole width between the straight supports or feet g, g of refractory brick.
The two boilers properly so called B and F are arranged parallel and axially with
respect to the boiler and between the said boilers there are interposed along their
whole length tubular separation pieces or sockets j,j of cast steel in which large tubes k,k
are fixed, the said tubes all passing to a greater or less extent into the interior of
the upper boiler F. By this means permanent communication is established between
the two chambers or boilers B and F. The upper boiler or chamber also com
municates by pipes i, with the steam dome or collector C which is arranged
horizontally at the top of the generator and from which steam is taken.
On each side of the boilers B and F the heating tubes E, A, and E¹, F1, also
communicate with one another along their whole length by vertical pipes or tubes 1,
which are placed in position by being passed through these heating-tubes and
then screwed or expanded into position in sets of about three into sockets or
connections m,m riveted to the heating-tubes.
All the doors for charging the furnace, inspecting the apparatus, and cleaning 'the

page_text: same as well as all the manholes for examination and cleaning are arranged on the
front of the boiler whereby the rear end of the same can be placed against a wall or
the like so as to considerably economize space. The doors M are for charging the
furnace with fuel and for inspection, the doors N for cleaning the tubes c, c the
doors P for cleaning the tubes d, d and the doors Q for cleaning the vertical passage or
pipes, and for inspection.
The tubes c, c, d, d are tightly expanded into the tube-plates of the cylindrical
chambers which they place in communication so as to obtain tight joints. These
tubes to a certain extent support the whole of each boiler B and F and the corres-
ponding heating-tubes. They have the important advantage of being interchangeable
which is not the case with curved or bent tubes. Expansions take place all in the
same direction and to the same extent for each series of tubes so that no oblique
strain, which can tend to destroy the tightness of the joints around the tubes is
exerted upon the tube-plates.
The whole arrangement of boilers Band F of heating-tubes and of their respective
clusters of tubes is therefore arranged under most favourable conditions with regard
to resistance, erection and rigidity and the construction permits worn tubes to be
quickly and easily replaced.
The furnace is surrounded by refractory brick and is therefore under good conditions
for effecting efficient combustion. The gases heat the lower heating-tubes and rise
whilst burning into the chamber or space o which has the form of an inverted V and
is formed by the tubes c,c. This arrangement of heating-tubes A, A' and bundles
or clusters of tubesc, c has the advantage of offering a very large heating surface to the
radiating heat of the furnace. On leaving the chamber o the gases flow in diverging
directions between the tubes c, c between which as above described wide passages are
provided and give up a large part of their useful heat as they progressively cool, the
arrangement being such that the said gases are energetically agitated.
On issuing from the tubes c, c the gases of combustion reach the spaces or
chambers o', o' where they finish burning and come into contact with the upper
heating-tubes E, E; they then pass between the tubes d, d which divide them into
thin layers, cool them considerably and utilize their remaining heat through the
medium of the upper boiler F. The waste gases finally pass through the orifice S
partly on leaving the tubes d,d and partly after having passed around the upper part
of the boiler F and the lower part of the dome or collector C.
By this means a maximum heating surface is obtained and the cooling of the gases
is as effectual and efficient as is possible.
As the lower heating-tubes and the bundles of tubes placed above the furnace are
strongly heated and produce a considerable amount of steam which by mixing with
the water filling the tubes c, c causes a considerable agitation or formation of current,
it will be obvious that an extremely rapid circulation of water is obtained. The water
circulates from the heating-tubes A, A¹ towards the boiler B across the large
tubes c, c then from the boiler B towards the boiler F through the tubular separating
pieces and the vertical tubes k which also serve to keep up the circulation. The
current then flows downwards in two directions and passes through the upper inclined
tubes d, d into the heating-tubes E, E. Finally the flow continues from the heating-
tubes E, E¹ towards the heating-tubes A, A¹ through the large vertical tubes or
passages l. By this means a complete cycle and a methodical and efficient circulation
are obtained which effect the efficient utilization of the heat given up by the gases
of combustion to the metal walls of the generators.
The water supply or feed is effected at any point in the cylindrical bodies B and F
or in the heating-tubes but preferably at the upper rear part of the heating-tubes A, A¹.
It will be obvious that I can modify the number and the diameters of the water-
tubes forming the inclined clusters or bundles and that I can arrange the tubes in
any other suitable manner in their tube-plates. It will also be obvious that the
vertical passages I connecting the heating tubes with one another can be screwed or
otherwise fixed into their connections mor if desired replaced by simple upright-
tubes. I can also arrange in the path of the gases of combustion and at suitable

page_text: points therein baffles screens or the like for retarding the flow of the said gases
towards the chimney and to keep them longer in contact with the walls of the
generators.
It will be understood that my boilers can be constructed of varying power and that
they can be arranged in groups of any number, for instance in groups of two arranged
end to end and that each boiler can be formed with two heating-tubes instead of with
four.
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. A marine boiler formed of two semi-multitubular generators each comprising a
boiler, properly so called, connected by two bundles or clusters of inclined straight
tubes to two heating-tubes, the said generators (which only differ from one another
in the diameter of their water-tubes) being connected together, the boilers to the
boilers and the heating-tubes to the heating-tubes, in such a manner as to effect the
practically complete combustion of the furnace gases and to provide a continuous
water circulation and so operating as to furnish steam to the dome or collector
arranged at the upper part of the apparatus, substantially as described.
2. In a marine boiler of the kind described in Claim 1 the employment of two
boilers, properly so called, B and F arranged one above the other and communicating
by large tubes k with two heating-tubes A, A¹ arranged symmetrically with respect to
the boiler B, of two heating tubes E, E' arranged symmetrically with respect to F
and respectively placed in the same vertical plane as the heating tubes A and A¹ with
which they communicate by vertical passages l, l, the lower heating-tubes A, A¹ being
connected to the boiler B by inclined bundles or clusters formed of large straight
tubes c, c of the same length and having between them large passages for the gases
of combustion, whilst the upper heating-tubes E, E¹ are connected to the body of the
lower boiler F by inclined bundles or clusters formed of straight tubes d, d of small
diameter and of the same length and arranged near together so as to suitably cool
the gases before they reach the chimney, substantially as described and illustrated in
the accompanying drawing.
3. In a marine boiler of the kind described in Claim 1 the tube-
plates a, a, e, e¹, b, b¹, f,f arranged parallel to one another in pairs and in which
the tubes c, c, d, d are expanded, the said plates forming a part of the wall of the
heating tubes A, A¹ and E, E¹ and of their respective boilers B and F, substantially
as described and illustrated in the accompanying drawing.
300k
ated this 2nd day of June 2007.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.