IMPROVE- MENTS IN STEAM BOILERS
Year: 1868

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery
Lane, in the County of Middlesex, for the Invention of "IMPROVE-
MENTS IN STEAM BOILERS."-A communication from abroad by
Alexandre Lagrafel, Engineer, of 29, Boulevart St. Martin, Paris.
Sealed the 7th July 1868, and dated the 20th January 1868.
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 20th January 1868.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN STEAM BOILERS," to be as follows:-
This Invention relates to improvements in steam boilers more
especially applicable for river and sea service, with high pressures and
a fresh or salt water feed, the object of the Invention being the
production of a boiler of which the whole surface exposed to the
action of the flame is composed of tubes.

page_text: In order to render the improvements readily understood I have in
the accompanying Drawings shown them as applied to a boiler of 120
horse power.
Figure 1, Sheets 1 and 2, shows a longitudinal section of the improved
boiler, the upper and lower portions of the Figure being connected at
the lines, a, and the section being taken on lines 1, 2, Figure 3,
Sheet 5, and 3, 4, 5, 6, Figure 2, Sheets 3 and 4.
Figure 2, Sheets 3 and 4, shows a front clevation of the boiler, the
two parts of the Figure being united at the lines y, z, the Figure being
partly in section on the lines 7, 8, Figure 1, Sheets 1 and 2, and 9,
10, Figure 3, Sheet 5.
Figure 3, Sheet 5, shows a sectional plan of the boiler on the
line 11, 12, Figure 1, Sheet 2, while Figure 4, Sheet 6, shows a sectional
plan on the line 13, 14, Figure 1, Sheet 1.
The general exterior form and the proportions between the length, 1
breadth, and depth of the boiler are suited for placing on board ship.
The boiler is composed of one or more shells constructed in the following
manner: The upper part is composed of a casing A of semi-cylindrical
form placed in a horizontal position with the convex part above, the
flat part at bottom forming a tube plate. This chamber serves as
a steam and water space, and at each of its four angles is fitted a
vertical water-heating tube B; also serving as a support for the part A.
Vertical tubes C are also fitted around the casing, forming with the
heating tubes B the furnace enclosure; these tubes C are fixed at top
to the horizontal surface of A, forming a tube plate, and are closed at
bottom, they being filled with water and heated on the exterior. The
fire-bars D occupy the whole space circumscribed by the tubes C and
heating tubes B. The two vertical supports or heating tubes at the
front of the boiler are intersected by a horizontal heating tube E at
about their mid height, forming the top of the firc-door F, and also
serving to support a row of tubes G placed as close together as possible.
at a slight inclination and bent upwards, so as to connect them to the
upper tube plate, thus forming a kind of roof to the furnace. All the
remaining space in the horizontal surface of A is studded with vertical,
conical, or cylindrical tubes EL filled with water and closed at bottom.
Thus there are three distinct series of tubes. 1st. The vertical

page_text: tubes C and B, forming the sides of the furnace chamber. 2ndly. The
bent tubes G, forming the top of the furnace, both series being heated:
direct by the action of the flame on their surfaces; and 3rdly, the
vertical, conical, or cylindrical tubes EL, which in order to obtain
increased heating surface are heated by the flame forced to pass
through the bent tubes G in its passage to the chimney I.
I place.
the tubes as close together as possible without weakening the tube
plate. Bricks are placed behind the vertical tubes C with a backing
of plate iron strengthened by angle plates removable in panos,
forming the outside of the boiler. Bricks J are also placed on the
bent tubes G to close in the roof of the furnace, so as to direct the
flames towards and between the bent ends of said tubes. In order
to establish a circulation in the tubes so as to prevent their being
destroyed by the heat I adopt one arrangement among those in use
for the purpose, which consists in placing a vertical partition h
therein, as seen, extending to within a short distance of the bottoms of
the said tubes. An ascending current is thus established on the side
which is the most heated, and a descending current on the cooler side..
This plate in the vertical tubes C serves at same time as a means of
fixing the plugs at the bottoms of said tubes. This arrangement is not
required in the bent tubes for creating a current, there being but a
single current passing upward from the horizontal tube E into the
casing A. I may also place a cast-iron collecting tube at the lower"
part of the boiler, as shown by the red lines, into which open all the
vertical tubes C, while the hinder supporting tubes may be dispensed with,
and circulating tubes substituted therefor. In this manner by placing
the front of the collecting
cocks and doors for extracting the salt at
tube all the vertical tubes may be cleared at one time, any deposits
taking place during the time the boiler is not in use having a tendency
to fall to the lowest and coolest parts, where they are readily extracted.
It will be seen that this boiler has but one plane surface, viz., the
tube plate before mentioned, all the principal parts being of cylindrical
form, and consequently capable of resisting great internal pressure. It
is necessary that the tube plate should be strengthened as much as
possible, and it may also be slightly curved or arched, as well as the
front plate K, L, for a similar purpose, although this plate is not exposed
to the heat, nor are there any flat surfaces, rivets, stays, nor adjuncts
exposed to the fire.

page_text: All makers of marine boilers know how frequent and costly are the
repairs necessary in those at present in use in consequence of the for
the most part flat surfaces of the furnace or fire-box necessitating the
employment of rivets, stays, and of two or three thicknesses of sheet
metal, the whole being exposed to a violent heat. Boilers on this
improved system however need not be removed from the vessel, and
the whole of the tubes may be readily changed, producing as it were
a new boiler; the total weight is also much reduced. Steam pressure
may also be obtained in less time, and in case any part should burst
there will be less hot water escaping. These boilers are particularly
advantageous for river service, and also at sea when surface condensers
are used, that is to say, with a fresh water supply. Boilers on this
principle may also be used for land engines.
The chief features of this Invention are,-
1st. The almost total reduction of flat surfaces.
2ndly. Dispensing with the furnace dome and with all rivets, stays,
and extra thicknesses of plates at the joints, and substituting therefor
a series of bent inclined tubes surrounded by the flames at all parts,
through which passes a continuous current of water.
3rdly. Dispensing with the ordinary furnace and fire-box surfaces,
and substituting therefor vertical cylindrical tubes having an internal
continuous current of water.
4thly. The facility with which the boiler can be dismounted while
in place, and any part renewed if injured by the heat.
5thly. Great lightness of construction combined with greater strength
to resist internal pressure.
.
6thly. The water distribution enables it to be heated quicker for the
purpose of obtaining pressure, while more perfect combustion is obtained
with less expenditure of fuel.
7thly. All saline and other incrustations are collected at the lower
parts, which are protected from the action of the fire.

page_text: 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 18th July 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twentieth day of January, in the
year of our Lord One thousand eight hundred and sixty-eight, 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 Inven-
tion for "IMPROVEMENTS IN STEAM BOILERS," a communication to me from
abroad by Alexander Lagrafel, Engineer, 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 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 two
Sheets of Drawings hereunto annexed, and to the letters and figures
marked thereon (that is to say) :-
This Invention relates to improvements in steam boilers, more
especially applicable for river and sea service with high pressures, and
a fresh or salt water feed, the object of the Invention being the pro-

page_text: duction of a boiler of which the whole surface exposed to the action of
the flame is composed of tubes.
In order to render the improvements readily understood I have in the
accompanying Drawings shown them as applied to a boiler of 120 horse
power.
Figure 1 shows a longitudinal section of the improved boiler taken on
lines 1, 2, Figure 3, and 3, 4, 5, 6, Figure 2.
Figure 2 shows a front elevation of the boiler partly in section on the
lines 7, 8, Figure 1, and 9, 10, Figure 3.
Figure 3 shows a sectional plan of the boiler on the line 11, 12,
Figure 1, while Figure 4 shows a sectional plan on the line 13, 14,
Figure 1.
The general exterior form and the proportions between the length,
breadth, and depth of the boiler are suited for placing on board ship.
The boiler is composed of one or more shells constructed in the
following manner:-The upper part is composed of a casing A of
semi-cylindrical form, placed in a horizontal position with the convex
part above the flat part, at bottom forming a tube plate. This chamber
serves as a steam and water space, and at each of its four angles is fitted
a vertical heating tube B, also serving as a support for the part A. 1
Vertical tubes C are also fitted around the casing, forming with the
heating tubes B the furnace enclosure. These tubes C are fixed at
top to the horizontal surface of A forming a tube plate, and are fitted
at bottom by the aid of glands to a collecting tube S, on which are also
mounted the lower ends of the vertical tubes B. In this manner all
parts of the boiler are placed in direct communication, suitable doors
and cocks being further provided in the collecting tube for emptying
the boiler, and removing or extracting the salts and other deposits
which may accumulate when the boiler is not in use at the lowest and
coolest parts. This collecting tube may if desired be dispensed with,
in which case the tubes C would be closed at their lower ends by
means of plugs as shown in red lines in the Drawing. This arrange-
ment also necessitates the application of diaphragms for producing
ascending and descending currents in tubes EL, which diaphragms also
serve for fixing the plugs in the ends of said tubes. The fire-bars D
occupy the whole space circumscribed by the tubes C and heating
tubes B. The two vertical supports or heating tubes B at the front of

page_text: the boiler are intersected by a horizontal heating tube E at or about
their mid height, forming the top of the fire-door F, and also serving to
support a row of tubes G placed as close together as possible at a slight
inclination, and bent upward so as to connect them to the upper tube
plate, thus forming a kind of roof to the furnace. All the remaining
space in the horizontal surface of A is studded with vertical, conical,
or cylindrical tubes H filled with water, and closed at bottom.
Thus there are three distinct series of tubes. 1st, the vertical tubes
C and B forming the sides of the furnace chamber; 2ndly, the bent
tubes G forming the top of the furnace, both series being heated
direct by the action of the flame on their surfaces; and, 3rdly, the
vertical, conical, or cylindrical tubes H, which in order to obtain
increased heating surface are heated by the flame forced to pass
through the bent tubes G in its passage to the chimney I. I place
the tubes as close together as possible without weakening the tube
plates. Bricks are placed behind the vertical tubes C with a backing
of sheet iron strengthened by angle plates removable in panels
forming the outside of the boiler. Bricks J are also placed on the
bent tubes G to close in the roof of the furnace so as to direct the
flames towards and between the bent ends of said tubes. In order
to establish a circulation in all the tubes H, so as to prevent their
being destroyed by the heat, I adopt one arrangement among those
in use for the purpose, which consists in placing a vertical partition h
therein as seen, extending to within a short distance of the bottoms
of the said tubes. An ascending current is thus established on the
side which is the most heated, and a descending current on the cooler
side.
This arrangement is not required in the bent tubes G for
creating a current, there being but a single current passing upward
from the horizontal tube E into the casing A. It will be seen
that this boiler has but one plane surface, viz., the tube plate before
mentioned, all the principal parts being of cylindrical form, and
consequently capable of resisting great internal pressure. It is
necessary that the tube plate should be strengthened as much as
possible, and it may also be slightly curved or arched as well as the
front plate K, L, for a similar purpose although this plate is not exposed
to the heat, nor are there any flat surfaces, rivets, stays, or adjuncts
exposed to the fire.
All makers of marine boilers know how frequent and costly are the
repairs necessary in those at present in use in consequence of the furnace

page_text: or fire-box being composed for the most part of flat surfaces, neces-
sitating the employment of rivets, stays, and of extra thicknesses of
metal, the whole being exposed to a violent heat. Boilers on this
improved system however need not be removed from the vessel, and the
whole of the tubes may be readily changed, producing as it were a new
boiler, the total weight is also much reduced. Steam pressure may also
be obtained in less time, and in case any part should burst less hot water
will escape. These boilers are particularly advantageous for river
service, and also at sea when surface condensers are used, that is to say,
with a fresh water supply. Boilers on this principle may also be used
for land engines.
For boilers with triple furnaces I may instead of the single collecting
tube S, which is made of U form, employ three independent tubes, the
two in a parallel position would carry the vertical tubes forming the
sides or flanks of the furnace, while the third tube would carry the
vertical tubes forming the back of the boiler next the furnace. This
latter collecting tube is placed at right angles to the two lateral tubes
on their hinder ends, communicaton being established between them
by means of a tube or tubes, so as to render them independent of each
other when desired. I may also without departing from the principle
of the Invention employ the following arrangement in boilers with
two, three, or more furnaces:-The fire bars are divided into as many
sets as there are furnaces, each of the latter being separated by a double
row of vertical tubes (similar to the tubes C before referred to), forming
the sides of the furnace. Each double row of tubes opens at bottom into
a collecting tube, which collecting tubes are placed in parallel positions,
and independent one of the other. The vertical tubes forming the back
of the furnace are received at their lower ends in a collecting tube
placed transversely at right angles thereto. All the vertical tubes both
of the sides and back are received at their upper ends in a tube
plate forming the base of a dome-shaped chamber, divided into spaces of
equal number to the furnaces by means of partitions rising vertically
in the space comprised between the double rows of tubes. These par-
titions
may
if desired be perforated for placing all parts of the chamber
in communication. The collecting tube for the back tubes is also
placed in communication with each of the other collectors by means
of junctions.
The chief features of this Invention arc,-

page_text: 2ndly. Dispensing with the furnace dome, and with all rivets, stays,
and extra thicknesses of plates at the joints, and substituting therefor
a series of bent inclined tubes surrounded by the flames at all parts,
and through which a continuous current of water passes.
.
3rdly. Dispensing with the ordinary furnace and fire-box surfaces,
and substituting therefor vertical cylindrical tubes having an internal
continuous current of water.
4thly. The facility with which the boiler can be dismounted while in
place, and
any part renewed if injured by the heat.
5thly. Great lightness of construction combined with greater strength
to resist internal pressure.
6thly. The water distribution enables it to be heated quicker for the
purpose of obtaining pressure, while more perfect combustion is obtained
with less expenditure of fuel.
7thly. All saline and other incrustations are collected at the lower
parts, which are protected from the action of the fire.
Having described the nature of this Invention, and the manner of
performing the same, I declare that what I claim as the improvements
in steam boilers more especially applicable for marine engines, and for
working at high pressures with a fresh or salt water feed is,-
First. I claim the vertical tubes C and heating tubes B, forming the
outside surface of the boiler, which tubes may or may not be placed
in communication at bottom with a collecting tube S, or it may be
with several independent collecting tubes connected when desired
substantially in the manner shown and described.
Secondly. I claim the bent tubes G forming the roof of the tubular
furnace, disposed and arranged in the manner before described.
Thirdly. I claim the conical or cylindrical tubes H forming an
additional heating surface, in the manner shown and described.
Fourthly. I claim the chamber A forming the upper part of the
boiler, as herein-before shown and described.
Fifthly. I claim the horizontal heating tube E placed over the furnace
door in the manner shown and described.
Sixthly. I claim the combination and arrangement of parts herein
described, whereby the ordinary furnace dome is dispensed with, as

page_text: also all rivets, stays, and extra thicknesses of metal at the joints,
together with the side walls of the furnace and fire-box, the whole of
the parts being readily fitted and unfitted while in place, all in the
manner herein-before described.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Eighteenth day of July,
in the year of our Lord One thousand eight hundred and sixty-
eight