Improvements in Water Tube Steam Generators.
Year: 1898

page_text: Date of Application, 5th Aug., 1898
Complete Specification Left, 5th May, 1899-Accepted, 1st July, 1899
Improvements in Water Tube Steam Generators.
We, ALEXANDRE LAGRAFEL, and JULES FREDERIC MARIE JOSEPH D'ALLEST,
both of 40, Chemin de la Madragne, Marseilles, in the Republic of France,
Engineers, do hereby declare the nature of this invention to be as follows:-
This invention relates to an improved water tube steam generator.
66
This boiler is composed of a cylindrical reservoir and of a prismatic box termed
the water sheet" these two parts being connected by a system of tubes, varying
in length and by a certain number of pipes of a larger diameter, termed the return
flow pipes.
In the middle of the system of tubes an empty space termed the fire box is
provided by the suppression of a certain number of tubes; the function of this
fire box will be described further on; this said space is at its upper part limited
by two or three rows of tubes, at the back by the "water sheet" and at the front
by a set of tubes which, on the one hand, terminate in the reservoir and, on the
other hand, in a collector, which is, on its part, connected to the water sheet"
by means of a pipe of large diameter.
The lower row and the upper row of tubes forming the system, are covered by
brickwork the said system of tubes is moreover closed, upon the sides, by means
of a flat iron screen, extending over a certain height.
44
The reservoir, in which lies the water line or level, is provided with steam out-
lets as well as with safety- and feed-accessories; it is further fitted with a man-
hole allowing access to all the joints of the tubes; the two faces of the water
sheet" are rigidly tied or connected by stays; the rear face presents, opposite
each tube, an opening closed by a screw stopper, which enables the tubes to be
put in place to inspect and to clean them, by means of a brush with flexible
body, which is drawn through alternately by two assistants, one placed in the
chest or reservoir and the other behind the "water sheet."
The boiler proper, such as above described is fastened by bolts to a casing made
of plates and angle irons or of cast iron, forming a support and is fixed at its
base to the foundation; this casing contains the furnace and the ash pit; the
surrounding parts of the ash pits are provided with holes forming doors facing
the front; moreover there are other doors, provided in the sides; the grate,
divided into two by a fire bridge is placed below the first lower range of tubes;
at each side of the system of tubes, iron plates are provided, leaving between
them and the tubes a space, called the smoke-box; above the same a flat iron
casing is provided, from which the chimney starts.
The operation of the steam boiler is as follows:
1. CIRCULATION OF THE GASES.
The gases produced in each furnace pass into the fire-box, where they circulate
the fl" that
to

page_text: quantity of air traversing the gratings can be regulated and a complete and normal
combustion be ensured in the fire boxes.
After having passed the fire-box the gases become reversed upon themselves,
return to the right and left through the system of tubes, and enter the smoke
boxes, while passing along below the screens; the outlet section provided below
the screens, is determined by calculating the volume of the gases cooled down to
the temperature of the chimney; from the smoke box they pass away over the
system of tubes into a space, where they further heat the return flow pipes and
subsequently escape into the chimney.
2.
CIRCULATION OF THE WATER.
Under the action of the heat the water, contained in the tubes rises by reason
of the diminution of the specific weight, is partly converted into steam, and
ascends in the reservoir; this action produces a draught within the "water sheet"
which receives its feed from the water in the reservoir by means of return-flow
tubes; as these tubes are heated less than the other tubes and as the said tubes
are inclined from their starting point to an angle against the horizon, the direction
of the circulation is thus clearly determined and can not become reversed; it
will be understood that the tubes nearest to the gratings, which are the longest
and are heated the most, terminate in the reservoir above the water line; the
speed of the circulation which might be less therein than in the other, by reason
of their greater length, is thus increased; experience has demonstrated that, after
these tubes, those found to be most heated, were the tubes forming the upper part
of the system of tubes, this being due to the fact, that the hot gases present the
tendency of always first reaching the upper part; these tubes terminate below
the water line, but are shorter than the others, and, as all are of the same diameter
the speed of circulation is increased; the circulation in the tubes, which close the
fire box from the front, and which are not directly connected to "water sheet"
is ensured by the large return flow tube; and the small collector.
We have seen, that the fire box was obtained by omitting a certain number of
tubes in the centre of the system of tubes; the perimeter of this fire box is of
rectangular shape the long sides being in the vertical direction but the said fire
box may be made of rectangular shape with the long sides in the horizontal
direction; the first mentioned arrangement, termed "vertical fire box," is suitable
for high and narrow steam generators, whereas the second arrangement termed
"horizontal fire box" is appropriate for low and large generators. In the case
of the horizontal fire box, it is desirable in order to prevent the gases from passing
too rapidly through the system of tubes, to arrange a few small fire bricks, forming
a baffle and it is also necessary, in order to prevent them from passing in a too
direct manner toward the outlet that screens be placed between the said tubes.
In the first arrangement the water sheet" is composed of a single piece; it
should, however be remarked that it may be in two, three or any number of
vertical parts, without it being therefore necessary, to modify the length of the
reservoir.
This "water sheet" may however be composed of a series of cylindrical reser-
voirs communicating with each other at the top and bottom by tubular joints or
connections; the return flow of water into these cylinders may be effected, either
through a set of tubes, at the ratio of one tube per cylinder, or through two thick
pipes, starting at each end of the lower part of the reservoir and terminating
at the top or at the bottom of the two extreme cylinders; the tubes of the system
are bent from the point, where they start from the cylinders, so that their joint
is always placed radially; against each one of them a screw stopper is arranged
to enable them to be put in place and for cleaning purposes: instead of a stopper
being arranged opposite each tube, larger openings may be provided to serve for
a certain number of tubes at a time.
In conclusion I attach value to the fact that the arrangement proper of this
improved generator, more especially differ from certain other generators, in as

page_text: much as the tubes are curved and as all of them terminate in the upper reservoir,
and as the return flow is effected through special tubes; these differences are
essential, because the curved tubes are less subject to being deformed than straight
tubes, further because their direct arrival in the upper reservoir diminishes the
height of the column of ebullition or series of inflowing currents and lastly because
the whole of this arrangement permits of constructing a much lighter and less
cumbersome generator.
The cleaning which, in our old type of generators could only be effected from
the side owing to the water sheet" at the front, is, in this improved type effected
directly and very easily from the furnace itself, by way of doors, arranged upon
the front, above the furnace doors.
The replacement of the tubes is likewise effected through the furnace, the tubes
to be taken out or to be put in place are passed along the intervals of the vertical
ranges.
Natal thi, kal
1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.
We, ALEXANDRE LAGRAFEL, and JULES FREDERIC MARIE JOSEPHI D'ALLEST,
both of 40, Chemin de la Madragne, Marseilles, in the Republic of France,
Engineers, 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 an improved water tube steam generator and is here-
inafter described with reference to the accompanying drawings, in which:
Figure 1 is a vertical transverse section of a type of boiler constructed in
accordance with our invention, the said section being taken on the line 1, 2, 3, 4, 5
of Figure 2.
Figure 2 is a vertical longitudinal section of the same passing through the system
of tubes at right angles to the section shown in Figure 1
Figure 3 is a section, similar to Figure but passing through the fire box;
Figure 4 is a horizontal section on line 6-7 of Figure 3;
Figure 5 is a horizontal section partly on the line 1, 2, 3, 4 and partly on the
line 1, 2, 5, 6 of Figure 6 showing a modified form of boiler.
Figure 6 is a vertical longitudinal section of the same and
Figure 7 is a vertical cross section thereof passing through the axis of the chest
and through the fire box.
The boiler shown in Figures 1, 2, 3 and 4 is composed of a cylindrical reservoir A
and of a prismatic box B termed the "water sheet or water plate these two parts
being connected by a system of tubes C varying in length and by a certain number
of pipes D of a larger diameter, termed the return flow pipes.
In the middle of the system of tubes Ca space E, termed the fire box is pro-
vided by the omission of a certain number of tubes; the function of this fire box
will be hereinafter described; this said space is at its upper part limited by two
or three rows of tubes, at the back by the "water sheet" and at the front by a
set of tubes F which, on the one hand, terminate in the reservoir A and, on the
other hand, in a collector G, which is, on its part connected to the ". water sheet"
by means of a pipe of large diameter.
The lower row and the upper row of tubes forming the system C, are covered by

page_text: brickwork I, as indicated in the drawing; the said system of tubes is moreover
closed, upon the side, by means of flat iron screens K, extending over a certain
height.
The reservoir A, in which lies the water line or level is provided with steam
outlets as well as with safety- and feed-accessories; it is further fitted with a
man-hole a, allowing of access to all the joints of the tubes C; the two faces of the
66 water sheet" are rigidly tied or connected by stays; the rear face presents,
opposite each tube, an opening b closed by a screw stopper or plug, not represented
in the drawing, which enables the tubes to be put in place, to inspect and to
clean them, by means of a brush with flexible body, which is drawn through
alternately by two assistants, one placed in the chest or reservoir and the other
behind the water sheet."
"
The boiler proper, such as above described is fastened by bolts to a casing J
made of plates and angle irons or of cast iron, forming a support and is fixed
at its base to the foundation; this casing contains the furnace and the ash pit;
the surrounding parts of the ash pit are provided with holes forming doors LL
facing the front; moreover there are other doors, M M provided in the sides; the
grate, divided into two by a fire bridge N, is placed below the first lower range
of tubes, at each side of the system of tubes, iron plates are provided, leaving
between them and the tubes a space l', called the smoke-box; above the same a
flat iron casing is provided, communicating with the chimney R.
The operation of the steam boiler is as follows:
1. CIRCULATION OF THE GASES.
The gases produced in each furnace arrive in the fire-box, where they circulate
and are completely burnt; if care be taken to cross the feed" that is to say to
feed alternately the right and left hand furnaces, the variations in the quantity
of air traversing the gratings can be regulated and a complete and normal com-
bustion. be ensured in the fire boxes.
After having passed the fire-box the gases become reversed upon themselves,
return to the right and left through the system of tubes, and enter the smoke
boxes; while passing along below the screens; the outlet section, provided below the
screens is determined by calculating the volume of the gases cooled down to the
temperature of the chimney; from the smoke box they pass away over the system
of tubes into a space S, where they further heat the return flow pipes and sub-
sequently escape into the chimney.
2. CIRCULATION OF THE WATER.
Under the action of the heat the water, contained in the tubes C, rises by
reason of the diminution of its specific weight, is partly converted into steam.
and ascends in the reservoir A; this action produces a draught within the water
sheet B, which receives its feed from the water in the reservoir A by means of
return-flow tubes 1); as these tubes are heated less than the other tubes Cand
as the said tubes are inclined from their starting point to an angle against the
horizon, the direction of the circulation is thus clearly determined and cannot
become reversed; it will be understood that the tubes nearest to the gratings,
which are the longest and are heated the most, terminate in the reservoir A above
the water line; the speed of the circulation, which might be less therein than
in the others, by reason of their greater length, is thus increased; experience has
demonstrated that, after these tubes, those found to be most heated, were the
tubes forming the upper part of the system of tubes, this being due to the
fact, that the hot gases present the tendency of always first reaching the upper
part; these tubes terminate below the water line, but are shorter than the others,
and, as all are of the same diameter, the speed of circulation is increased; the
circulation in the tubes F, which close the fire box from the front, and which
are not directly connected to the "water sheet," is ensured by the large return flow
tube H and the small collector G.
We have seen, that the fire box was obtained by omitting a certain number of
tubes in the centre of the system of tubes; according to Figure 1, the perimeter

page_text: 16
al
of this fire box is S, T U V; but the said fire box may be made of another shape
and its perimeter might be for example S T U V₁as shown in Figure 7; the
first mentioned arrangement, termed a vertical fire box," is suitable for high
and narrow steam generators, whereas the second arrangement termed
horizontal fire box" is appropriate for low and large generators. In the case
of the horizontal fire box, it is desirable, in order to prevent the gases from passing
too rapidly through the system of tubes, to arrange a few small fire bricks a b',
forming a baffle; and it is also necessary, in order to prevent them from passing
in a too direct manner toward the outlet, that screens c d be placed between the
said tubes.
In the arrangement shown in Figure 2 the water sheet is represented by a
single piece; it should, however, be remarked that it may be in two, three
or any number of vertical parts, without it being therefore necessary, to modify
the length of the reservoir A.
This "water sheet" may however be composed, as represented in Figures 5
and 6, of a series of cylindrical reservoirs B¹ communicating with each other,
at the top and bottom, by tubular joints or connections E¹ and F1; the return
flow of water into these cylinders may be effected, either through a set of tubes D'
at the ratio of one tube per cylinder, or through two large pipes, starting at each
end of the lower part of the reservoir A, and terminating at the top or at the
bottom of the two extreme cylinders B¹; the tubes of the system are bent
from the point, where they start from the cylinders B', so that their joint is
alway placed radially; against each one of them a screw stopper is arranged to
enable them to be put in place and for cleaning purposes; instead of a stopper
being arranged opposite each tube, larger openings may be provided to serve
for a certain number of tubes at a time.
In conclusion we attach value to the fact that the arrangement proper of this
improved generator, more especially differs from certain other generators, inas-
much as the tubes are curved and as all of them terminate in the upper reservoir,
and as the return flow is effected through special tubes; these differences are
essential, because the curved tubes are less subject to being deformed than the
straight tubes, further because their direct arrival in the upper reservoir
diminishes the height of the column of ebullition or series of inflowing currents
and lastly because the whole of this arrangement permits of constructing a much
lighter and less cumbersome generator.
<6
The cleaning which, in our old type of generator could only be effected from
the side, owing to the water sheet" at the front, is, in this improved type effected
directly and very easily from the furnace itself, by way of opening doors, arranged
upon the front, above the furnace doors.
The replacement of the tubes is likewise effected through the furnace; the
tubes to be taken out or to be put in place are passed along the intervals of the
vertical ranges.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
1. A water tube steam generator or boiler; the characteristic feature of which
consists in the combination of a prismatic box, termed the "water sheet," or of
cylindrical collectors, of an upper reservoir with the water line, of a system of
curved tubes, connecting the water-sheet" with the upper reservoir and all
terminating, in the latter; the said tubes serving to admit of the circulation of
the water from the water sheet to the reservoir; and of return flow pipes of a
larger diameter and less heated than the others, serving for the return flow of
the water from the reservoir to the "water sheet"; substantially as above
described.
2. In the steam generator of the kind described in the first claim, a fire box,

page_text: limited at its upper part by two or three or a certain suitable number of
ranges of tubes, at its back by the water sheet" (B) and at its front by a set
of tubes (F), which terminate, on the one hand, in the reservoir (A) and, on the
other hand, in a collector (G) which itself communicates with the "water sheet"
by means of a tube of a large diameter (H).
3. The arrangements, construction and combination of the whole device and of
the detail parts in types of water tube steam generators as herein described with
reference to Figures 1 to 4 and 5 to 7 of the accompanying drawings.
Dated this 5th day of May 1899.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.

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