Improvements in Multitubular Boilers.
Year: 1889

page_text: Date of Application, 28th Sept., 1889
Complete Specification Left, 25th June, 1890-Accepted, 26th July, 1890
PROVISIONAL SPECIFICATION.
Improvements in Multitubular Boilers.
I, JEAN FRANCOIS DURENNE of Courbevoie, Seine, France, Engineer, do hereby
declare the nature of this invention to be as follows:-
My invention relates to boilers of the kind in which the flames and hot products of
combustion act on the external surfaces of a number of tubes communicating with
water spaces, my object being to obtain, with comparatively small bulk and weight, a
powerful and rapidly acting boiler capable of sustaining high pressures and having its
interior easily accessible for cleansing or repairs. One form of boiler according to my
invention is of the vertical cylindrical type, having an outer water shell and an
internal fire box with central chimney passing through the upper space of the boiler.
Within the fire box I fit a number of tubes each of which is bent in a peculiar
manner. The lower limb projects horizontally and radially inwards from the water
shell, then it bends upwards and somewhat outwards and is secured to the annular
portion of the crown plate of the fire box surrounding the central chimney.
Each tube, owing to its bent form, is capable of expanding and contracting without
straining its jointings to the plates. The Hames and products of combustion, from the
fire below the tubes, are made to divide themselves in thin layers in passing through
the intervals between the horizontal limbs of the tubes, to collect again in the annular
space around the vertical parts of the tubes and then again to pass through the
intervals between the tubes on their way to the central chimney. The water is
caused to circulate rapidly up the tubes and down the shell, and in order to promote
this circulation, there may be a partition in the shell dividing an external descending
from an internal ascending current. In order to prevent priming and obtain dry
steam, a casing open at the top is fitted around the chimney in the steam space and the
steam pipe issues from this casing taking off steam somewhat superheated by contact
with the chimney.
In order to give access for cleansing or repairs, the outer shell is flange-jointed to
the lower part of the fire box and to a flange projecting around the chimney. By
undoing the bolts which secure these joints the outer shell is free to be lifted, giving
access to the shell of the firebox and to the mouths of the tubes. In cases where
there is not room to lift the shell its whole height, it may be made in two parts in
height with flange joints holding them together. By undoing the chimney joint and
the lower joint the whole shell can be raised sufficiently to give access to the lower
mouths of the tubes, and by undoing the chimney joint and the upper joint, the upper
part of the shell can be lifted to give access to the upper mouths of the tubes.
According to a modified form, the boiler is made in A form having two inclined
water spaces sloping inwards from two cylindrical water spaces at the bottom to a
cylindrical water and steam space at the top. The tubes in this case have thin lower
limbs projecting horizontally inwards from each inclined water space then they bend
upwards about the middle, and again bend outwards to the inclined water spaces.
The fire is arranged under the tubes in the front part of the boiler, and the flames
and products of combustion ascend in the intervals between the horizontal limbs of
the tubes, find their way past the vertical limbs and finally issue to the chimney
at the hinder part of the boiler. In this, as in the cylindrical boiler the jointings of
the tubes are relieved from strain, and there is a rapid circulation of the water up
the tubes and down the outer water spaces. The outer shells are made with openings
provided with covers, by removing which access is obtained to the mouths of the
tubes.
Dated this 28th day of September 1889.
ABEL & IMRAY,
Agents for the Applicant. +

page_text: COMPLETE SPECIFICATION.
Improvements in Multitubular Boilers.
I, JEAN FRANCOIS DURENNE of Courbevoie, Seine, France 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:-
In the various constructions of vertical tubular boilers at present in use, the tubes
are either pendant or of loop shape, and retain in their internal part, which is
exposed to the flames, a certain quantity of deposits and solid matter, which more
or less rapidly renders them useless.
The construction of such boilers also has the inconvenience of leaving centrally
between the tubes a considerable free space through which the combustion gases rise
directly to the chimney, thus causing a great loss of beat. This latter defect has to
a certain extent been obviated by placing centrally between the tubes a baffle plate,
which in forcing the gases to diverge laterally causes them to come partially in
contact with the tubes. Such baffle plate is however defective in its attachment, and
increases the weight of the apparatus, and when the boiler is moved from one place to
another it comes in frictional contact with the tubes and injures them.
According to my present invention I construct such tubular boilers in such a
manner that the baffle plate is dispensed with, and that the combustion gases are
utilized in a more advantageous manner by increasing the length of their travel, and
in dividing them so that they come into effectual contact with the surfaces of the
tubes.
My invention is applicable to the construction of both vertical and horizontal
boilers I will describe two arrangements with reference to the accompanying
drawings by way of example.
Fig. 1 shews a vertical section, of a vertical boiler with tubes constructed according
to my invention. Fig. 2 shews a cross section on line a b Fig. 1 and Fig. a cross
section on line c d. Within the internal shell or fire box V of the boiler are arranged
a number of tubes T having their lower ends bent horizontally and attached in several
tiers to the shell V, from which they consequently project radially towards the centre,
and then curve upward so as to close almost entirely the central passage and
consequently obstructing the direct upward passage of the combustion gases. An
annular space O is thus formed between the upper part of the shell V and the inward
bent parts of the tubes.
The upper ends of the tubes are bent outwards from the centre again in order to
afford room for the central orifice of the chimney flue, and they are fixed in the
crown C of the fire box. With this arrangement the combustion gases, no longer
finding a free passage at the centre, are dispersed throughout the interstices between
the tubes, effectually imparting their heat first to the horizontal part of the tubes
situated immediately above the fire grate, and uniting again in the annular space 0
where any remaining combustible gases are consumed and whence they again disperse
among the interstices between the upper parts of the tubes in order to arrive at the
chimney orifice.
The circulation of the water takes place in first descending along the surface of the
outer shell A and then entering the lower parts of the tubes through which it flows
upwards with such great velocity that no deposit or incrustation is possible; the
deposits are all effected in the lower part of the boiler, below the lowest tier of tubes,
where the water is comparatively calm and without movement.
In order to control still further the direction of circulation of the water, there
might be placed in the annular water space an annular partition of thin sheet metal,
perforated at the lower part, so that the water descending between the outer shell A
and the partition, will pass through the holes of the latter and rise between this and
the inner shell V before entering the tubes.
Owing to the great velocity of the water in the tubes, it would be projected from
the upper ends thereof with considerable violence against the upper surfaces of the

page_text: shell A, causing water to mix with and pass off with the steam. I prevent this by
placing over the crown of the fire box a perforated plate. The steam is further dried
by causing the discharge steam pipe to communicate with the interior of an annular
chamber D with perforated sides surrounding the chimney flue, so that the steam, in
order to pass out through the discharge pipe, has first to pass round in the chamber D
in close contact with the hot chimney flue.
The removal of the outer shell A is facilitated by constructing it with an angle-iron
joint secured by screw bolts at d at any suitable point below the level of the tubes T,
and a second joint with screw bolts at on the crown F of the shell. The internal
heads of the bolts are made hemispherical.
Owing to the peculiar curved form and mode of attachment of the tubes T, they are
free to expand and contract without straining their connections.
In order to avoid the considerable height required in the workshops for removing
and replacing the shell A, it may be constructed in two or more separate parts
secured together by external bolted joints, as shewn to a smaller scale at d d and d, d,
in Fig. 4. For gaining access to the interior of the tubes, the shell A is raised to a
height X sufficient to uncover the lower openings of the tubes T, and distance pieces e
are then bolted to the flange joints dd, thus leaving free access to the lower ends of
the tubes. The upper joint d d of the shell is then separated, and the top part is
raised to the height y and distance pieces el are introduced between the flanges, thus
forming an opening through which access is gained to the upper ends of the
tubes.
Thus it will be seen that the outer shell will only have been raised the total
heighty instead of having to be raised the full height of the fire box V plus the
distance y, as would be the case if the shell were all in one, and which would in many
cases be very inconvenient.
Fig. 5 shews a longitudinal section and Fig. 6 a cross section of a horizontal boiler
with my invention applied thereto. This boiler is constructed of two lower water
cylinders B B and an upper cylinder E which contains water and the steam space.
This cylinder E is connected to each cylinder B by flat collecting chambers, the
sides of which are tied together by tie bolts, so as to afford them the requisite
strength.
The inner faces of these chambers which are exposed to the fire are formed with
holes at their upper and lower parts into which are fixed the ends of the bent water
tubes T. These tubes are formed with several curvatures suitably arranged so that
they can expand and contract without straining the joints, and they are so arranged
as to approach each other closely at Z at the bottom parts from either side, so as to
prevent in great measure the direct upward current of the gases, only leaving
sufficient room between them to allow for their expansion at that point. These tubes
are arranged in one or more parallel tiers, three such tiers being shewn on the
drawing.
The gases are thus made to spread out laterally, and penetrate through the
interstices between the tubes along the horizontal parts thereof in order to enter the
spaces O formed between the sides of the chambers H and the tubes T, in which
spaces the unconsumed gases enter into combustion with the air carried along with
them, the resulting flames and hot gases passing away through the interstices between
the upper parts of the tubes.
The outer surfaces of the chambers G are formed with openings opposite the part
of the inner surface in which the tubes T are fixed so that access can be gained to
these, the said openings being closed by covers p secured by screw bolts.
For regulating the circulation of the water in the chambers G, there is introduced
therein a sheet iron partition H which divides the chamber G into two parts; in the
inner part the highly heated water and steam rise into the cylinder E, as indicated by
the arrows, while the cooler water descends from the cylinder E through the outer
spaces of G to the cylinders B.
Owing to the direct heat to which the tubes T are subjected, the water circulates

page_text: with great rapidity therein, and is thrown with force from the upper orifices against
the partitions H along which it rises into the cylinder E.
The above described construction of boilers affords the following advantages.
1. The boiler occupies a reduced space, as compared with known constructions.
2. Its weight is comparatively small on account of the large amount of heating
surface it offers.
3. It is moveable and is readily erected and cleaned, and
4. Steam can be rapidly raised, therein with an economical consumption of fuel.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed I declare that what I
claim is
The improved construction of steam boilers with curved water tubes projecting at
their lower parts to the centre of the fire box while the upper parts are made to
diverge from the centre again, thereby forming lateral chambers or spaces between
the shell of the boiler and the inner curved surfaces of the tubes through which spaces
the gases circulate, and in which their combustion is completed, the said boilers being
constructed substantially as herein described with reference to the drawings.
Dated this 25th day of June 1890.
ABEL & IMRAY,
Agents for the Applicant.