IMPROVEMENTS IN TUBULAR BOLLERS
Year: 1867

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, for the Invention of "IMPROVEMENTS IN
TUBULAR BOLLERS."- A communication from abroad by Louis Barret,
Dock Engineer Marsailles and of on Balon SM Danie
Sealed the 12th May 1868, and dated the 13th November 1867.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents, with his Petition, on the
13th November 1867.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN TUBULAR BOILERS," to be as follows:―
This Invention relates to improvements in tubular boilers with a view to
remedy the defects of those now used for marine engines, but which improve-
ments are also applicable to stationary, locomotive, and all other apparatus for
heating or evaporating liquids. These generators are based on the application
of direct-beating surfaces with a water and steam circulation, and it has been
proved that in order to obtain at all parts of the generator exposed to the
direct action of the furnace or flames a continuous and uniform production of
steam perfectly continuous and non-intermittent ascending and descending
currents of steam and water must be produced in the heated water.
I a

page_text: aware that the circulation of water has been obtained by means of a second
tube open at the base and placed inside the first tube, but these improvements
consist in creating a continuous circulation in the tubes and around the flues
by means of diaphragms or partitions in a much simpler manner.
In order to render the Invention clear I have in the accompanying
Drawings represented one example of its application to a stationary engine
boiler, although as above mentioned the improvements are applicable as well
to marine, locomotive, and other boilers generally.
Figure 1 shows a partial longitudinal section of a boiler constructed
according to these improvements; and Figure 2 an end elevation partly in
section at the furnace end of the boiler. The same letters apply to the two
Figures. These improved boilers are provided with vertical conical tubes a, a,
on the outside of which the flame impinges; the lower end of each tube is
closed by a plug 6 as in the "Field" tube while its upper end is fixed in the
ordinary manner to a strong horizontal and perfectly flat tube plate c,
strengthened at intervals by ribs d similar to those in the roof of a locomotive
fire-box. Each tube a is provided in its interior with a vertical plate or
diaphragm reaching to within 6th of an inch of the bottom and so as to
divide the water contained into two equal parts in a plane perpendicular to
the direction of the flames, this division plate serves to establish a continuous
current of water in the tubes which is so rapid that all matters in suspension
such as salts or even denser matters are carried away and leave no deposit in
the bottoms of the tubes while the furnace is in action; the ascending current
of heated water and steam passes up on the side a¹ of the tube facing the
direction of motion of the flames, while the descending current of cold water is
established on the other side a² which is heated to a much less degree
than the other. If the tubes are to be placed in a vertical boiler directly
under the furnace, where the whole exterior surface would be equally exposed
to the action of the fire, it is necessary in order to produce a current of water
in the interior to incline the diaphragms more or less instead of placing them
vertically in the tubes. Without the continuous current established in the
tubes a by means of the diaphragms f this system of boiler would presen
grave objections the steam and heated water formed at the lower part of the
tubes under the direct action of the flames could not rise to the surface of the
water except the tension of the steam were sufficient to discharge from the
tube the column of water superposed, and as a short time would invariably
elapse before the cold water is precipitated into the tube to replace the steam
and water expelled the latter would become exposed to the injurious action o
the fire. Further these intermittent projections of water and steam produce

page_text: by the tubes would retard the formation of steam, and occasion the introduction.
of considerable quantities of water into the cylinders. The formation of steam
being also instantaneous for the moment might lead to the bursting of the
boiler.
In order that the continuous ascending and descending currents of steam.
and water produced above the furnace dome (as in marine boilers) may.
pass in any predetermined direction, I place division plates 9, Figure 3, below.
the flues containing the tubes forming diaphragms which are inclined more
or less in the water for directing the currents in the desired direction. This.
arrangement would suffice to obviate the objections to tubular boilers now
used in which the circulation of the ascending and descending currents is.
obstructed by narrow winding passages separating the tubes. This defective.
circulation sometimes endangers the metal forming the dome of the furnace,.
which is directly exposed to the action of the flame and heat radiating from.
the furnace, in fact the top of the furnace may often be seen. to. suddenly;
assume the form shown by the dotted lines in Figure 4, as a consequence on,
the one hand of the dome being in contact with the steam which cannot.
escape and on the other with the intense heat of the furnace chamber which.
produces so high a temperature that the metal can no longer resist the
pressure of the steam and is put out of shape. The mode of constructing
boilers I propose is at once simple and easy of execution, they are further-
readily kept in working order and cleaned, all the internal parts being easily
accessible, while in the boilers now in use on this principle the exterior
surface of the tubes becomes covered with salt which can only be removed.
with great difficulty, and is often so thick as to completely fill the space.
between the tubes, preventing the transmission of heat to the water and,
occasioning at same time such injuries to the tubes from heat as to render
them unserviceable. Steam pressure may be obtained in these improved
boilers on an average in less than an hour from the time of lighting the fires
as all the heating surfaces are exposed to the direct action of the flame, and
the volume of water contained being much less than in other boilers it is
evident that the time gained for lighting the fires and producing pressure
constitutes a sufficiently important advantage both in the military and
mercantile marine services. In a boiler of this construction the products of.
combustion are not forced to enter a large number of small tubes the orifices
of which are partially obstructed by the ferrules connecting them to the tube
plates. These tubes subdivide the flame and cool it to such a degree that it
becomes extinguished after traversing a small fraction of their length, and.
deposits on their interior a coating of black sticky soot forming a bad

page_text: conductor of heat, which solidifies under its action and impedes the draught
and transmission of the caloric of the gases to the water. The tubes aud
plate to which they are fixed are further not liable to be damaged by the
beat in consequence of the strong current of water established in the tubes.
The salts in suspension in the water while the boiler is in use, and which
may deposit in the tubes on the extinction of the fires, may be readily removed
by means of a conical wire brush and borer. It may be objected that it is not
possible to remove the salt depositing in the tubes every time that the fires
are lowered or extinguished, as it often happens that steam vessels make
stoppages not exceeding three or four hours' duration; in this case the salt
however will not have time to solidify or firmly adhere to the surfaces of the
tubes and immediately the boilers are raised to full pressure the current of
water carries away with it the salts that may have deposited at the bottoms of
the tubes. Lastly, this improved system may be readily applied to existing
boilers.
Lastly, this
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Melville Clark in the Great Seal Patent Office
on the 12th May 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 58, Chancery Lane, in the County of Middlesex, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of November, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Alexander Melville Clark, Her special licence that I, the said Alexander
Melville Clark, my executors, administrators, and assigns, or such others
as I, the said Alexander Melville Clark, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time and
at all times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN TUBULAR BOILERS," a communication to me from abroad
by Louis Barret, Dock Engineer, Marseilles, and of 29, Boulevart St.
Martin, Paris, upon the condition (amongst others) that I, the said Alexander
Melville Clark, my executors or administrators, by an instrument in writing

page_text: under my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said Alexander Melville Clark, do hereby
declare the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the six Sheets of Drawings
hereunto annexed, and to the letters and figures marked thereon (that is
to say):-
:-
This Invention relates to improvements in tubular boilers with a view to
remedy the defects of those now used for marine engines, but which improve.
ments are also applicable to stationary and locomotive engine boilers and all
other apparatus for heating or evaporating liquids. These generators are
based on the application of direct-heating surfaces with a water and steam
circulation, and it has been proved that in order to obtain at all parts of the
generator exposed to the direct action of the furnace or flames a continuous
and uniform production of steam, perfectly continuous and non-intermittent
ascending and descending currents of steam and water must be produced. I
am aware that the circulation of water in the tubes has been obtained by
means of a second tube open at the base, and placed inside the first tube; but
these improvements consist in creating a continuous circulation in the tubes
and around the flues by means of diaphragms or partitions in a much simpler
manner.
These improvements in tubular boilers are illustrated in the accompanying
Drawings, Sheet 1 of which shows a tubular marine boiler, for working at an
average pressure, constructed according to this Invention.
Figure 1 shows a part sectional elevation of the boiler on the line A, B,
Figure 2, which is a longitudinal section of the same on line C, D, Figure 1;
Figure 3, a horizontal section on lines E, F, G, H, Figure 2; Figures 4
and 5, a separate section and plan of a tube, while Figures 6 and 7 shows
plans of tubes having diaphragms or partitions of different forms.
Sheet 2 represents a high pressure marine boiler on this principle.
Figure 8 is a part sectional elevation of the boiler on line I, J, Figure 9,
which is a longitudinal section on line K, L, Figure 8; Figure 10 is a hori-
zontal section on lines M, N, aud O, P, Figure 9.
Sheet 3 shows a locomotive boiler constructed according to this Invention.
Figure 11 is a vertical sectional elevation of the boiler on line Q, R,

page_text: Figure 12, which is a longitudinal section of same on line S, T,
Figure 11.
Sheet 4 shows the improvements applied to a stationary boiler, Figure 13
being a longitudinal section of the boiler on line U, V, Figure 15; Figure 14
a plan of same on line X, Y, Figure 18; Figure 15 shows a part sectional
view of the furnace end on the line Z, Z, Figure 13.
Lastly, Figure 16 shows a sectional view at the smoke box end. The
same reference letters apply to all the Figures.
These improved boilers are provided with vertical tubes a, a, of taper form,
on the outside of which the flame impinges; the lower end of each tube is
closed by a plug b, as in the "Field " tube, while its upper end is fixed by
means of a collar made either by hand or otherwise, and fitted either with or
without a ferrule to a horizontal and perfectly flat tube plate c, strengthened
at intervals by ribs d similar to those in the roof of a locomotive fire-box.
This mode of fitting the tubes presents the advantage of enabling them to
be fitted or removed with the greatest facility, at same time obtaining a
perfectly tight joint. Each tube a is provided in its interior with a vertical
plate or diaphragm f reaching to within a short distance of the bottom, so as
to divide the water contained into two equal parts in a plane perpendicular to
the direction of the flames. This division plate serves to establish a con-
tinuous current of water in the tubes which is so rapid that all matters in
suspension, such as salts, or even denser matters, are carried away and leave
no deposit in the bottoms of the tubes; while the furnace is in action the
ascending current of heated water and steam passes up on the side a² of the
tube facing the direction of motion of the flame, while the descending current
of cold water is established on the other side a², which is heated to a much
less degree than the other. By placing these tubes with flat diaphragms in a
vertical boiler immediately over the furnace the whole of their external surface
would be uniformly heated, and a current could not be produced when
arranging the diaphragm as before mentioned so as to divide the heating
surface of the tube into two equal parts, hence in this case it is necessary
in order to obtain a current to divide the external heating surface into two
unequal parts by means of the diaphragm, which I obtain, 1st, by placing the
fat diaphragms in an inclined position; 2ndly, by employing diaphragms with
curved surfaces.
Figure 7 of the Drawings shows the diaphragms of semicylindrical form,
and Figure 6 of angular section, and so arranged as to divide by means of
their edges a, c, the external casing into two unequal parts a, c, d, a, b, c, care
being taken however to make the sections A, B, about equal one to the other

page_text: The ascending current will be established in the part B which presents the
larger heating surface, while the descending current passes through the part
A. The diaphragm is held firmly in position by means of two elastic supports,
one placed at the upper and the other at the lower part of the diaphragm.
When applying these diaphragms with curved surfaces to tubes placed in a
current of flame perpendicular to their axes, the said diaphragms, should be so
arranged that the larger heating surface may be directly exposed to the current
as shown in Figures 6 and 7 the arrows indicating the direction the flames
take. If the tubes are to be placed in a vertical boiler directly over the
furnace, where the whole exterior surface would be equally exposed to the
action of the fire, it is necessary in order to produce a current of water in the
interior to incline the diaphragm more or less instead of placing them vertically
in the tubes. Without the continuous current established in the tubes a by
means of the diaphragm f this system of boiler would present grave objections.
The steam and beated water formed at the lower part of the tubes under the
direct action of the flames could not rise to the surface of the water except
the pressure of the steam were sufficient to discharge from the tube the column
of water superposed, and as a short time would invariably elapse before the
cold water is precipitated into the tube to replace the steam and water expelled
the latter would become exposed to the injurious action of the fire; further
these intermittent projections of water and steam produced by the tubes would
retard the formation of steam and occasion the introduction of considerable
quantities of water into the cylinders. The formation of steam being also
instantaneous for the moment might lead to the bursting of the boiler. In
order that the continuous ascending and descending currents of steam and
water produced above the furnace dome (as in marine boilers) may pass in
any predetermined direction, I place division plates 9, Figure 1, below the
flues containing the tubes forming diaphragms which are inclined more or less
in the water for directing the currents in the desired direction. This arrange-
ment would suffice to obviate the objections to tubular boilers now used in
which the circulation of the ascending and descending currents is obstructed
by narrow winding passages separating the tubes. This defective circulation
sometimes endangers the metal forming the dome of the furnace which is
directly exposed to the action of the flame and heat radiating from the furnace,
in fact the top of the furnace may often be seen to suddenly assume the form
shown by the dotted lines in Figure 1, as a consequence on the one hand of
the dome being in contact with the steam which cannot escape and on the
other with the intense heat of the furnace which produces so bigh a tempera-
ture that the metal can no longer resist the pressure of the steam and is put

page_text: out of shape.
In existing boilers the parts most quickly destroyed are the
tubes, the furnace dome, and the lateral surfaces of the latter in consequence
of their being exposed to oxydation and the action of heat. As regards the
primary cause of this destruction, it is of course easy to find a remedy by
renewing those parts which become weakened by the above action. The
damage by heat is occasioned whenever the water does not reach the point
acted on, but these objections are entirely obviated in boilers on this system
both as regards the furnace dome and the tubes, as the currents created by
the diaphragms carry away the steam at the moment of its formation
and also prevent the deposit of salts. In order to produce similar currents
at the sides of the furnace, I place in the water space separating two
consecutive furnaces tubes h, Figure 1, of thin sheet iron, funnel shaped
at their upper part and held in the vertical position. by means of collars.
These tubes are formed in several parts easily detachable in the manner
of a smoke pipe and extending up from the fire bars to a level with the
plate closing the tubular flue. By this means the steain formed at the
sides of the furnace will readily disengage without being impeded by the
descending currents of cold water in the tubes h. The mode of constructing
boilers I propose is at once simple and easy of execution; they are further
readily kept in working order and cleaned, all the internal parts being easily
accessible, while in the boilers now in use on this principle the exterior surface
of the tubes becomes covered with salt which can only be removed with great
difficulty and is often so thick as to completely fill the space between the tubes
preventing the transmission of heat to the water and occasioning at same time
such injuries to the tubes from heat so as to render them unserviceable. Steam
pressure may be obtained in these improved boilers on an average in less than
an hour from the time of lighting the fires as all the heating surfaces are
exposed to the direct action of the flame and the volume of water contained
being much less than in other boilers it is evident that the time gained in
lighting the fires and producing pressure constitutes a sufficiently important
advantage both for the military and mercantile marine services. In a boiler
of this construction the products of combustion are not forced to enter a large
number of small tubes the orifices of which are partially obstructed by the
ferrules connecting them to the tube plates. These tubes subdivide the flame
and cool it to such a degree that it becomes extinguished after traversing a
small fraction of their length and deposits on their exterior a coating of black
sticky soot forming a bad conductor of heat which solidifies under its action
and impedes the draught and transmission of the caloric of the gases to the
water. The tubes and plate to which they are fixed are further not liable to

page_text: be damaged by the heat in consequence of the strong current of water
established in the tubes. The salts in suspension in the water while the boiler
is in use, and which may deposit in the tubes on the extinction of the fire, may
be readily removed by means of a conical wire brush and borer. It may be
objected that it is not possible to remove the salt depositing in the tubes every'
time that the fires are lowered or extinguished as it often happens that steam
vessels make stoppages not exceeding three or four hours' duration; in this
case the salt however will not have time to solidify or firmly adhere to the
surfaces of the tubes and immediately the boilers are raised to full pressure
the current of water carries away with it the salts that may have deposited at
the bottoms of the tubes. Besides possessing the advantage of being readily
detached the mode of fitting the tubes does not present the inconveniences
attaching to existing arrangements in which the collar m, Figure 18, Sheet 4,
not being in contact with the water contained in the boiler is destroyed in a
short time by the action of the flame while the head plates being no longer
held by the collars which serve to secure the same give way and cause the
joints to become leaky. This cannot take place in boilers on the improved
principle described as the tube ferrules and collars are constantly in contact
with the water. However in order to avoid having a double thickness of
metal exposed to the action of the flame the collar is fitted so as not to project
below the tube plate as shown in Figure 4, Sheet 1. The upper part of the
collar projects slightly above the tube plate so as to prevent the water expelled
from again entering the tubes. I also apply this system of tubes with internal
diaphragms to vertical boilers with internal fire boxes. For this purpose the
tubos are fixed to the internal casing, diaphragms with either flat or curved
surfaces being employed to produce continuous currents in the tubes.
To recapitulate the improven:ents herein-before described: 1st, the heating
surfaces are all directly exposed to the action of the furnace, whence results an
increased production of steam, economy in fuel, and considerable saving in time
in obtaining pressure; 2ndly, rapid currents of water are produced in the
tubes and at the dome and sides of the furnace by means of the diaphragms
with flat or curved surfaces and tubes of thin sheet iron. These tubes quickly
and uniformly heat the whole of the water, prevent the deposit of salts and
protect the casings from the action of the heat 3rdly, access may be had to
all parts of the boiler for cleaning and repairs; 4thly, the improvements are
applicable to all apparatus used for evaporating or heating liquids; 5thly, the
improvements may be readily applied at but small cost to all generators now in
use either for marine or land service.

page_text: Having described the nature of the Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein-before in part recited Letters Patent is,-
1st. The taper or cylindrical pendant or horizontal tubes a, one end of
which is closed by a plug, the other and open end being provided with a collar
made either by hand, or otherwise serving to connect the tube to the plate
with or without the aid of a ferrule and forming a perfectly tight joint.
2ndly. I claim the diaphragmn f with either flat or semi-cylindrical surfaces
or of angular section placed in the tubes above mentioned for the purpose of
producing the continuous circulation of the water and steam all as herein-
before described.
3rdly. I claim the vertical tubes placed in the water spaces separating the
furnaces for determining a circulation of the water therein.
4thly. I claim the arrangement of tube plate strengthened in the manner
described as also the form of tubular flue all as herein-before described and as
illustrated in the Drawings.
In witness whereof, I, the said Alexander Melville Clark, have hereunto
set my hand and seal, this Twelfth day of May, in the year of our
Lord One thousand eight hundred and sixty-eight.