IMPROVEMENTS IN STEAM BOILERS
Year: 1866

page_text: LETTERS PATENT to Richard Lewis, of Dublin, Engineer, for the Invention
of "IMPROVEMENTS IN STEAM BOILERS."
Sealed the 14th June 1867, and dated the 24th December 1866.
PROVISIONAL SPECIFICATION left by the said Richard Lewis at the
Office of the Commissioners of Patents, with his Petition, on the
24th December 1866.
I, RICHARD LEWIS, of Dublin, Engineer, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN STEAM BOILERS," to be as
follows:-
Instead of constructing steam boilers for marine and other purposes with a
series of tubes fixed between tube plates, I construct boilers according to my
Invention with a series of vertical flues of a parallelogram or other suitable
section connected with each other or together alternately at top and bottom,
thus forming a broad flat flue connecting the furnace with the main flue,
uptake, or chimney, and through which the flame and heated products of com-
bustion are caused to pass, alternately ascending and descending on their way
to the chimney or funnel.
By this arrangement and construction of flues a series of vertical surfaces
of considerable area are presented or interposed across the pathway of the
flame, and against which it is caused to impinge and remain in contact. In
the parts which connect the vertical portions of these flues at each end, or at

page_text: the bottom and top thereof, I fix one or several vertical tubes or conical flue
pieces of suitable dimensions so as to connect the water spaces with each
other, and by which, as well as by the spaces between the ends of the flues
and the sides of the boiler, I secure a free circulation of the water within the
boiler, and prevent the deposit of solid matter in the water spaces; they also
enable the steam as it is generated to escape and pass freely into the steam
chest. For the purpose of cleaning out any deposit of soot, ashes, or other
matter from the lower parts of the flues or bottom connecting pieces thereof,
I either join them to the sides of the boiler by means of a short tube or flue
piece with a man-hole fitted thereto (to give access to the interior of the flue
from time to time), or, in case the width of the ship does not permit of a
passage along the sides of the boiler, or when otherwise more convenient, I
provide access to the bottoms of each vertical flue by means of a short flue or
tube piece of sufficient diameter, connecting them with the top of the furnace
or furnaces, and fit each with a bonnet or cover.
By the novel arrangement of parts which I have described I am enabled
to secure a more perfect combustion of the gases than is possible in a multi-
tubular boiler; that by the impact of the flame upon and its retention for a
longer period in contact with the vertical plate surfaces of the flue more heat
is abstracted from the flame and heated products of combustion than is the
case where the heating surfaces are parallel to the direction of the passage of
the flame, or approximately in the shortest or most direct line between the
furnace and the chimney; moreover, the heated gases are retained for a much
longer time within the boiler than within a multitubular boiler in consequence
of the greater distance through which they have to travel. It is also self-
evident that the surfaces being all plain and of considerable area, combined
together in the manner described, can be easily got at for the purpose of
cleaning, and can be thoroughly repaired without the expense of removing
parts that do not require repairing, for the purpose of obtaining access to those
that do, and, moreover, unlike the tubes of a multitubular boiler, these flues
can be made to wear out the shell and other parts of the boiler.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of December, in the year of our
Lord One thousand eight hundred and sixty-six, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Richard Lewis, Her special licence that I, the said Richard Lewis, my exe-
cutors, administrators, and assigns, or such others as J, the said Richard Lewis,
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 STEAM BOILERS,"
upon the condition (amongst others) that I, the said Richard Lewis, 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 Soal
Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
"
NOW KNOW YE, that I, the said Richard Lewis, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, and the accompanying Sheet of Drawings :—
Instead of constructing steam boilers for marine and other purposes with a
series of tubes fixed between tube plates, I construct boilers, according to my
Invention, with a series of vertical flues of a parallelogram or other suitable
section connected with each other or together alternately at top and bottom, thus
forming a broad flat flue connecting the furnace with the main flue, uptake,
or chimney, and through which the flame and heated products of combustion
are caused to pass, alternately ascending and descending on their way to the
chimney or funnel.
By this arrangement and construction of flues a series of vertical surfaces
of considerable area are presented or interposed across the pathway of the
flame, and against which it is caused to impinge. In the parts which connect
the vertical portions of these flues at each end, or at the bottom and top
thereof I fix one or several vertical tubes or conical flue pieces of suitablo
dimensions so as to connect the water spaces with each other, and by which,
as well as by the spaces between the ends of the flues and the sides of the
boiler, I secure a free circulation of the water within the boiler, and prevent
the deposit of solid matter in the water spaces; they also enable the steam as

page_text: it is generated to escape and pass freely into the steam chest. For the
purpose of cleaning out any deposit of soot, ashes, or other matter from the
lower parts of the flues or bottom-connecting pieces thereof, I either join
them to the sides of the boiler by means of a short tube or flue piece with a
man-hole fitted thereto (to give access to the interior of the flue from time to
time), or in case the width of the ship does not permit of a passage along the
sides of the boiler, or when otherwise more convenient, I provide access to
the bottom of each vertical flue by means of a short flue or tube piece of
sufficient diameter connecting them with the top of the furnace or furnaces,
and fit each with a bonnet or cover.
By the novel arrangement of parts which I have described I am enabled
to secure a more perfect combustion of the gases than is possible in a multi-
tubular boiler; thus by the impact of the flame upon and its retention for a
longer period in contact with the vertical plate surfaces of the flue more heat
is abstracted from the flame and heated products of combustion than is the
case where the heating surfaces are parellel to the direction of the passage of
the flame or approximately in the shortest or most direct line between the
furnace and the chimney; moreover, the heated gases are retained for a much
longer time within the boiler than within a multitubular boiler, in consequence
of the greater distance through which they have to travel. It is also self-
evident that the surfaces being all plain and of considerable area, combined
together in the manner described, can be easily got at for the purpose of
cleaning, and can be thoroughly repaired without the expence of removing
parts that do not require repairing for the purpose of obtaining access to those
that do; and, moreover, unlike the tubes of a multitubular boiler, these flues
can be made to wear out the shell and other parts of the boiler.
DESCRIPTION OF THE DRAWINGS.
In the accompanying Sheet of Drawings I have shewn eight views of
boilers in accordance with my Invention.
Figure 1 is a front sectional elevation of a double-furnace boiler of the
marine type suitable (for instance) for a tug steamer or similar purpose;
Figure 2 is a vertical section of Figure 1 taken on the line A, B, thereof.
In these Figures the flues constructed according to this Invention are
shown as extending from end to end of the boiler (or section or piece of
boiler) except to allow for a water and steam space on each side of the boiler
shell, as shewn at C, so that looking at the section of a boiler constructed
according to my Invention from the furnace front, each front or back part of
the flue presents a parallelogram; the top as well as the bottom portion of the

page_text: interior parts of the boiler which form the flue are arched, the top portions
which form the dependent flue surfaces are arched above, whilst the lower
portions which form the erect flue surfaces are arched below, as shewn in
Figure 2 at D and D¹, in which D, D, form the three arches, from or between.
which the dependent portions of the flue spring or project downward, whilst
D', D', form the two inverts or inverted arches from which the three flue
pieces project upward and rise midway between the dependant portions below
the arches D, D, and which when combined together form a tortuous,
undulating, or "corrugated" passage or flue by which the furnace is connected
with the chimney, so that the flame and heated products of combustion are
caused to impinge repeatedly against plain, flat, and curved surfaces of con-
siderable area or extent on their way from the furnace to the chimney. In
these Figures 1 and 2, the general details of the mode of "staying" the
interior of the boiler are omitted for the purpose of greater clearness (as is
the case too in all the other views); but I have shewn the upper part of each
of the lower of the vertical flue pieces or divisions connected to the crown of
each arch of the upper portious by means of tubes a to permit of the ready
escape of the steam from the lower to the upper part of the boiler as it is
generated, and by which the more rapid circulation of the water is promoted.
I have shewn each of the three vertical divisions forming the lower portion
of the flue as being thus connected with the upper portion of the boiler with
two tubes, as will be seen by the dotted lines in Figure 1, and generally in
section in Figure 2, a, a, a.
I have also shewn in Figures 1 and 2 two arrangements by which any soot
collected in either of the inverts may be readily removed. The first mode of
effecting this is by means of two short vertical flue pieces or tubes as, at E,
Figure 1, formed in the crown of or over each furnace, which when the
furnace is in use are each closed by means of a plate or door piece; the second
mode or method shown is by means of short tubes inserted in the side of the
boiler shell, as at F, Figure 1, and which openings to the inverts of the flues
are each closed by means of a door or cover piece; and I prefer to fit these
cover pieces with "tale" or glass, so that the state of the combustion in each
portion of the flue may be readily watched.
In some cases I prefer that both the lower and upper bends of the flue
plates be connected together for the purpose of promoting circulation of the
water, and permitting of the free escape of the steam as it is generated, as is
shewn in Figures 3 to 8 inclusive; and where conical or taper instead of
parallel tubes can be employed, more especially in the lower bends of the flues
I prefer to employ them (as shewn at 6 in Figures 7 and 8.

page_text: In Figures 1 and 2 the passage ways or tubes between the crown of each
furnace and the lower bends of the flue are shewn as being fitted with cover
plates c, having a set screw and cross bar as a means of securing them in their
places, but any other means of closing them may be employed.
Figures 3 and 4 shew another modification and exhibit a smaller type of
marine boiler to that shewn in Figures 1 and 2; in this boiler there are no
tubes over the furnaces, and no means shewn of withdrawing the soot which
may collect in the bottom of each of the lower bends of the flue by means of
doors and passages of communication over each furnace, but lateral openings
or passages are provided at F, by which access to the lower bends of the flue
is commanded, as before described. In these views the inner bend of each of
the lower portions of the flue is connected with the outer bend thereof by
means of a short tube, as herein-before mentioned, by which the circulation
of the water and escape of the steam is aided; in these views two such
tubes d are shewn in each of the lower bends, and they are placed or disposed
immediately over the crown of each furnace. In these views, as in Figures 1
and 2, three upper bends in the flue have each three connecting tubes a in
the width of the flue.
'
Figures 5 and 6 are sectional views of a marine boiler having three furnaces,
and of which boilers (or pieces of boilers) it is intended to combine two such
in one chimney, or there may be four such pieces combined together, as is
commonly done for marine engines of great power. In these views which are
respectively taken
upon the section lines P, Q, Figure 8, and N, O, Figure 7,
and as indicated on the Drawing, the necessary modifications in the form and
arrangement of the parts and proportions of the boilers are made to suit the
requirements of a ship in the Royal Navy or mercantile marine, and a very
usual external form of outline has been adopted. In Figure 6 the take-up T
below the root of the chimney is shewn as being suitably enlarged to receive
a superheater S, and an ordinary arrangement of pipes P, valves V, and
connections therewith is shewn. The central furnace only has connecting
passages or tubes E (fitted with cover plates) between the lower bends of the
flue and the crown of the furnace. Each of the lower bends of the flue is
shewn in Figure 5 as having two connecting tubes d in the width of the flue,
which flue extends, as in every other case, from side to side of the boiler, or
nearly the full width thereof. The upper bends of the flues (three in number,
as shewn in Figure 6) have four connecting tubes a for the escape of the
steam formed between the inner bend of the lower parts of the flue.
Figures 7 and 8 are sectional views of a modification of the boilers shewn
in Figures 5 and 6, and in which conical or tapered connecting tubes bare

page_text: employed in the lower bends of the flue, as also an inverted conical tube e in
the first of the upper bends. Side passages F are also introduced at one side
of the boiler, as shewn in section in Figure 7, for the purpose of giving access
to the lower bend of each tube.
In the following description similar letters are employed to denote
corresponding parts. I is the shell or outside casing of the boiler; I, the
furnace; K, the tortuous, undulating, or corrugated passage or flue, by which
the furnace I is connected to the uptake T; a, the tubes connecting the top
of the inverts to the crown of the opposing arches, whilst d are the tubes con-
necting the lower water spaces; at b is shown a modification of these tubes,
the lower end being enlarged to allow a freer egress of the steam.
Another modification of the connecting water tubes is shewn at e, Figure 8,
where the upper end of the tube is enlarged. At E is shewn the short tubes
or flues in the crown of the furnaces, in order to facilitate the cleaning out of
the undulating flue K.
Another method is shewn at F, where a door or man-hole is formed to
enable the flues to be cleaned from the side of the boiler. D and D' shew
the arches and inverted arches respectively of the tortuous or corrugated
flue; C are water spaces on each side of the flue; T is the uptake leading
to the chimney. At S a superheater is shewn fixed in the usual manner, and
connected to the steam chest of the boiler by means of the pipes P and stop
valves V.
Although in the accompanying Drawings I have shewn three turns or
downward changes in the directions of the current whilst passing through
the flue between the furnace and the chimney I prefer in some cases to use
or employ two only, and instead of the third and last curved passage to
introduce a series of vertical or horizontal tubes towards the front of the
boiler; and although I do not intend to limit myself to the number of curved
pieces or parts of the flue or passage interposed between the furnace and the
chimney I find in practice that two or three complete changes in the direction
of the current are generally sufficient for the purpose of abstracting the
greater portion of the available heat produced by the combustion of the best
qualities of fuel on the maximum area of fire-grate surface usually allotted
in practice to each horse power. In every case the flue or passage for the
flame and products of combustion is formed by a continued series of flat and
curved surfaces, forming when combined a tortuous and undulating flue, having a
series of vertical plates against which the flame and products of combustion
act directly, and which being placed at right angles to the direct or horizontal
line between the furnace and the chimney, and having ou the other side

page_text: thereof a body of water to abstract the heat (for the purpose of generating
steam) form or produce a series of parallelogram passages extending in
length nearly the entire width of the boiler, and in width of such dimensions
or proportions as will permit of the necessary area being given to carry off
the products of combustion at a suitably low velocity as to ensure the thorough
abstraction of the heat from the products of combustion before they reach the
chimney.
I am aware that heretofore various contrivances have been made and
introduced for a like purpose, such as hanging bridges, pendant sheet-water
spaces, sheet-water traffle plates, and other arrangements of sheet-water
spaces, and I am also aware that transverse sheet-water spaces of the width
of each furnace have heretofore been introduced in various forms and shapes,
and disposed variously over, around, and behind each furnace; but I wish
it to be understood that my Invention does not relate to any such arrangements
or dispositions of sheet-water spaces, but to the construction and formation of
marine steam boilers with flues of the form and description as herein-before
stated, and of which some illustrations are given in the Drawing accompanying
this my Specification; and, moreover, as I have herein-before stated, I do not
limit or confine myself to the number of turns in the said flue, or to constructing
boilers with flues of the form or description herein set forth alone or with
tubes placed vertically or horizontally between the outer end of such flue, or
the end nearest to the chimney or the "uptake," and, moreover, such tubes
may be advantageously introduced horizontally immediately beyond the furnace,
and by preference, such tubes should contain the water within them, the
fire acting externally, as such an arrangement whilst it aids the circulation
of the water and the rapid generation of steam within them admits of their
being placed sufficiently wide apart to prevent the flame produced by the
furnace being broken or interrupted until it reaches the undulating flue.
When it is desired to separate the furnace passages behind the bridge of
each furnace a brickwork division may be introduced, as is commonly done;
such division may be carried to any convenient height, and when desired
division plates may be introduced within the flues constructed according to
the present Invention; but in practice any such arrangement has not been
found desirable.
Having now described my Invention of "Improvements in Steam Boilers,"
and the accompanying Drawings illustrating some of the modes in which I
prefer to put my Invention into practice in marine steam boilers of the types
therein shown, I wish it to be understood that what I claim is,-
First, the construction of marine boilers with undulating flues as herein

page_text: described extending from side to side of the boiler, and with one or more
complete turns between the furnace and "uptake," or the chimney, as
herein described and set forth.
Second, the use or employment of a series of undulating passages forming
a flue, the transverse length of such flue or passage exceeding the width of
the furnace or the several furnaces of a marine boiler, and the horizontal
transverse or sectional area of such flue or passage way being a parallelogram,
the width of which may be of any convenient dimension, whilst the length
shall be approximately that of the width of the boiler less only such thickness
of the water space as may be desired.
Third, the construction of marine boilers (whether used for marine or
other purposes) with an undulating flue, as herein-before described and as
illustrated in the accompanying Drawings, either alone or in combination
with horizontally or vertically disposed tubes, as herein-before described and
set forth.
Fourth, the construction of steam boilers, whether for marine or other
purposes, with an undulating flue or tortuous passage between the furnace
nud "uptake" or chimney, as herein described, wherein the pendant or
dependant portions of the flue are connected with the invert of the lower
portion thereof by means of tubes or vertical connecting picces, whilst the
vertical portions of the lower part of the flue are connected by means of
tubes or vertical connecting pieces of which there may be one or several in
the transverse length of the flue represented by the width of the boiler.
Fifth, the mode or method herein described of giving access to the inverts
of the flue, for the purpose of cleansing and repairing, as herein described,
and as shewn in the accompanying Drawings.
In witness whereof, I, the said Richard Lewis, have hereunto set my
hand and seal, this Twenty-second day of June, in the year of our
Lord Oue thousand eight hundred and sixty-seven.
RICHARD LEWIS. (L.S.)
Witness,
W³. H. WEBB.