Improvements in Steam Boilers.
Year: 1895

page_text: Date of Application, 26 h Aug., 1895
Complete Specification Left, 14th Mar., 1896-Accepted, 18th Apr., 1896
PROVISIONAL SPECIFICATION.
Improvements in Steam Boilers.
I, ETIENNE LAGOSSE, of 3 Rue de Lancry, 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 or generator which participates of the
nature of a cylindrical boiler and of the multitubular system and which combines
the advantages of both. I call it "semi-multitubular generator.'
"
My boiler is constructed of a pair of cylinders and of a cylindrical vessel or
boiler which surmounts them and which is in communication with them through
four clusters of tubes symmetrically arranged.
The clusters placed in front above the fire-grate are composed of tubes of
relatively large diameter having wide passages left between them for the passage
of the gases from the furnace.
The clusters situated at the rear are, on the other hand, composed of tubes of
much smaller diameter and placed very near each other.
The back portion of the pair of cylinders slopes over the space preceding the
chimney flue; the cleaning or extraction of deposits is effected from this side
through their end.
The cylindrical vessel or boiler is of ordinary construction but its diameter is
determined by the length of the tubes which are put in place and removed by
passing them through the said vessel; towards the lower part facing the cylinders
it is flattened and V-shaped.
The cylinders each have a flat side opposite the flat portions or sides of the
boiler or vessel.
The tubes are firmly fixed in the flat portions and in a manner tie together the
vessel or boiler and the cylinders.
The brickwork divides the flues into two parts by means of a vertical extension
of the bridge.
The furnace is surrounded by brickwork.
The gases heat the front lower portion of the cylinders and rise and become
mixed in the large chamber formed by the clusters of tubes having the form of an
inverted V. This arrangement of the cylinders and tube-clusters has the great
advantage of affording a very extensive heating surface for the heat radiating from
the furnace. On leaving the chamber formed by the clusters of tubes, the gases
take two different directions and pass through the front clusters which offer wide
passages to them and progressively cool them whilst the arrangement angleways of
the tubes causes an energetic mixture of the gases of combustion. Upon leaving
the front clusters, the said gases enter the large flues where they complete their
combustion and act upon the boiler or vessel and descend through the rear clusters
which divide them into thin streams, and quickly cool them and, assisted by the
back part of the cylinders, utilize the remaining heat, finally the gases pass into
the chimney.
As the part of the cylinders and the tube-clusters placed above the fire-place are
highly heated and produce a considerable quantity of steam which, by mixing with
the water in the tubes, forms therein a strong draft, it will be understood that an
extremely rapid circulation of water must result.

page_text: The water again descends through the rear clusters; in this manner it circulates
from the front to the back in the boiler or vessel, and from the back to the front in
the cylinders: a perfect cycle is thus established which forces the mud and
calcareous salts to collect in the lower part of the cylinders whence they are
withdrawn at proper intervals.
The feed is effected at the rear upper portion of the cylinders. The exterior
cleaning of the clusters is effected by means of a jet of steam; doors are provided
for this purpose in the front and rear faces of the furnace and the position of the
tubes as well as the course of the gases enable this cleaning to take place almost
automatically.
A man-hole in the boiler or vessel and another in each of the cylinders allow of
inspection, repairs and cleaning.
Dated this 26th day of August 1895.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
Improvements in Steam Boilers.
I, ETIENNE LAGOSSE, formerly of 3, Rue de Lancry, now of 7 Rue de
Maubeuge, 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 he
particularly described and ascertained in and by the following statement :-
My invention relates to a steam boiler of the semi-multitubular type, that is to
say, a boiler having a cylindrical vessel or upper drum and cylinders or lower
drums, the invention consisting in the peculiar arrangement of the water tubes,
which are straight, of equal length and serve to hold together the upper and lower
drums and are divided into clusters or sets extending from the grate to the
chimney, those nearest the grate being of large diameter and having between
them large passages for the flow of the gases and those nearest the chimney being
of smaller diameter and close together so as to effectually cool the gases before they
pass into the chimney.
To enable these tubes to be fixed in position the upper steam and water drum
and the lower drums have a part of their under surface made flat and formed of a
tube plate rivetted on to the cylindrical body.
My semi-multitubular boiler can be very easily cleaned both internally and
externally and is very simple in construction.
To enable my invention to be fully understood I will describe the same by
reference to the accompanying drawing, in which :-
Figure 1 is a front elevation of a boiler constructed according to my invention :
Figure 2 is a longitudinal section on the line 1-2 of Figure 1:
Figure 3 is a horizontal section on the line 3-4 Figure 2:
Figure 4 is a cross section one half being on the line 5-6 and the other half on
the line 7-8 of Figure 3:
Figures 5, 6 and 7 are details of the water tubes shewing the manner in which
they are attached to the tube plates of the drums.
The boiler is composed of two lower drums b, 6¹ and of a steam and water
drum arranged above them and communicating with them by four clusters or sets
of tubes, c, c, d, d' which are arranged symmetrically as shewn in Figures 2, 3
and 4.
The sets c, c', which are arranged in the front part of the boiler above the
grate, are composed of tubes of relatively large diameter which have between
then large spaces for the passage of the gases of combustion.
The sets d, d arranged at the back are, on the contrary, composed of tubes of

page_text: considerably smaller diameter arranged very close together for the purpose of
effectually cooling the gases before their passage into the chimney.
At
The rear ends of the drums b, b¹ project into the space in front of the chimney
flue. Cleaning or removal of deposits is effected towards these ends of the drums.
The upper drum a is of known construction but its diameter is determined by
the length of the tubes, which are inserted and removed through the same.
its underside opposite the drums it is provided with tube plates p, p¹ forming
between them a sort of V with opened cut limbs or branches as seen in Figures 4
and 5.
The drums b, b¹ are also provided with tube plates 62, 6³ to corresponding to and
parallel with the plates of the drum a.
The tubes c, c, d, d' are expanded in their respective plates p and b³, p² and b³ so
as to obtain steam tight joints as shewn clearly in Figures 6 and 7.
These tubes support to a certain extent the drum a and the drums b and b¹ and
possess the advantage of being interchangeable which is not the case with curved
tubes such as are employed with certain boilers of this class and which are well
known. Expansion takes place in the same direction and equally in each series of
tubes, so that no oblique force is set up in the tube plates tending to destroy the
tightness of the joints around the tubes. The arrangement of the drums and
tubes is very favourable with respect to the strength of the boiler, facility of
erection, good joints and ease and rapidity with which worn tubes can be replaced
by new ones.
Brickwork divides the flues transversely into two parts by means of the upward
extension of the bridge g (Figures 2 and 3). The hearth being surrounded with
brick is well adapted for the generation of heat.
The gases heat the front lower part of the drums and rise, whilst combining and
burning, into the large V shaped space m formed by the sets of tubes c, c'. This
relative arrangement of the lower drums and tubes has the advantage of offering a
large surface to the radiating heat of the hearth.
On issuing from the space m the gases proceed in two different directions as
shewn by the arrows in Figures 3 and 4, that is to say, they pass across the two
sets of tubes c, c', which allow them a free passage and take up nearly all their
useful heat, cooling them gradually. The diagonal arrangement of the tubes
produces an agitation in the gases.
The gases after passing through the sets of tubes c, c' enter the flues k, k¹, which
are of large section, where their combustion is completed under the drum a,
Figures 2 and 4, and then descend through the rear sets of tubes d, d¹ which
divide them into thin layers cooling them and abstract the remainder of their heat
being assisted in this by the rear portion of the lower drums; the gases exhausted
of their heat finally reach the chimney.
:
As those portions of the lower drums and the sets of tubes placed above the
hearth are strongly heated and produce a considerable amount of steam, which by
mixing with the water in the tubes causes considerable agitation in the same it
follows that a rapid circulation of water results. The water redescends through
the rear sets of tubes so that it circulates from the front to the back in the
drum a (Figure 2) and from the back to the front in the lower drums. By this
means a complete cycle is obtained which causes impurities and calcareous salts to
collect at the lowest part of the lower drums from which they can be removed
when required.
The boiler is fed at the upper rear ends of the lower drums b, b¹. The tubes are
cleaned externally by means of a jet of steam. Doors are arranged for this
purpose in front of and behind the furnace and the position of the tubes and the
direction of circulation of the gases are such that this cleaning operation is almost
effected automatically.
In
The tubes are cleaned internally by means of periodic operations and if there is
any incrustation formed in the drums it is removed in the ordinary manner.
connection with the cleaning of the tubes 1 may remark that the rapidity of the

page_text: circulation coupled with the nearly vertical position of the tubes assists in
preventing the formation of deposits.
A man-hole in the boiler and also one in each of the drums b, b' suffice for
overhauling and cleaning.
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 :-
1. A semi-multitubular boiler wherein the water tubes which connect the upper
and lower drums are inclined, straight, of the same length and divided into four
sets c, c, d, d' symmetrically arranged, those near the grate being composed of
tubes of large diameter and separated from one another and the others being
composed of tubes of small diameter and arranged close together near the chimney
substantially as described.
2. In a boiler of the kind described in Claim 1 forming the steam and water
drum a with straight tube plates p, p' at its lower part opposite the lower drums
the said plates being arranged in the form of a V with the limbs opened out
substantially as described.
3. In a boiler of the kind described in Claim 1 the combination with a steam and
water drum having on its underside tube plates forming a V, of drums b, b1 having
corresponding tube plates 62, 63 which are also flat and arranged parallel to the
corresponding parts of the drum a the said plates being rivetted to their respective
drums substantially as described.
4. In a boiler of the kind described in Claim 1 the combination with the drum a
and with the drums b, b¹ of water tubes c, c' and d, d¹ which are rigidly expanded
in the tube plates p, b² and p¹, 63 in such a manner that they assist in rigidly
connecting the upper and lower drums at the same time forming tight joints.
5. A semi-multitubular boiler comprising the steam and water drum a,
drums b, b', water tubes c, c, d, d' expanded in the tube plates of the drums, the
whole in combination with an upwardly extended fire-bridge which divided the
flues of the boiler transversely into two parts and causes the water to circulate
from the front of the lower drums towards the upper steam and water drum
through the large tubes, then from the front towards the back of this boiler, upper
drum, from the back of the upper drum to the rear ends of the lower drunis,
through the small tubes, and finally from the back towards the front of these tubes ;
whilst the gases of combustion at first in contact with the front portion of the
lower drums b, b' and the large tubes, are then caused to flow between these large
tubes, then to pass towards the back flowing over the sides of the fire-bridge and
finally to work towards the lowest part and at the same time to pass between the
small tubes before reaching the chimney substantially as described.
6. The improved steam boiler hereinbefore described and illustrated in the
accompanying drawing.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.