IMPROVEMENTS IN BOILERS AND APPARATUS FOR GENERATING STRAM AND EVAPORATING FLUIDS
Year: 1867

page_text: LETTERS PATENT to Thomas Dunn, of Pendleton, in the County of
Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN BOILERS
AND APPARATUS FOR GENERATING STRAM AND EVAPORATING FLUIDS."
Sealed the 3rd September 1867, and dated the 16th March 1867.
PROVISIONAL SPECIFICATION left by the said Thomas Dunn at the
Office of the Commissioners of Patents, with his Petition, on the
16th March 1867.
I, THOMAS DUNN, of Pendleton, in the County of Lancaster, Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
BOILERS AND APPARATUS FOR GENERATING STEAM AND EVAPORATING FLUIDS," to be
as follows:-
My improvements consist, first, in making the roofs of the fire-boxes of
steam boilers and the under side of evaporating pans with corrugations, the
object being to increase the strength and heating surface, and to prevent the
adhesion of scale or other deposit inside the boiler or pan. These corrugations
when applied to evaporating pans for salt give so much additional strength
that the metal plates may be much thinner than usual, and consequently
the deposit can be loosened by the vibration produced by striking the pan
with a wooden mallet, and the picking with steel nosed hammers so
injurious to the pan is avoided.
Secondly, the general arrangement of the parts of a marine steam boiler
having the fire-box above, and the multitubular portion below, also connecting

page_text: the fire-box to a top flue which is opened for lighting the fire, or when the
lower part of the boiler is flooded and is closed for usual work.
Thirdly, in the general arrangement of the parts of a marine boiler with
firing door above, and a flue formed of water partitions below in lieu of
tubes, also enclosing the lower part of the boiler and flues, so that in case
of the vessel leaking no injury is done until the water rises to the fire-bars.
Fourthly, in the application of slabs and blocks of fire-clay in vertical
boilers to increase the consumption of smoke.
Fifthly, the application of a large water pipe with side slabs of fire-clay
to form the partition in single upright boilers.
Sixthly, the combination of two or more single upright boilers united to
a central chimney, and capable of being connected or disconnected at
pleasure, for cleaning or repairing; the portions of this compound boiler
being similar any portion may be removed and a spare one kept for the
purpose put in its place.
Seventhly, the application of an inverted Barlow's railway rail, Patent
dated 23 January 1849, and numbered 12,438, to the under side of a
cylindrical boiler to form a channel for the feed water and for collecting
the deposit.
Eighthly, in applying the pipes inside the internal flues of boilers to heat
the feed water instead of beyond the boiler as is now usually the custom.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Dunn in the Great Seal Patent Office on the 14th
September 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
DUNN, of Pendleton, in the County of Lancaster, Engineer, seud greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixteenth day of March, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Thomas Dunn, Her special license that I, the said Thomas Dunn,
my executors, administrators, and assigns, or such others as I, the said
Thomas Dunn, 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,

page_text: che Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS
IN BOILERS AND APPARATUS FOR GENERATING STEAM AND EVAPORATING FLUIDS,"
upon the condition (amongst others) that I, the said Thomas Dunn, 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 Thomas Dunn, do hereby declare the
nature of my said Invention, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following Specifica-
tion thereof, reference being had to the three accompanying Sheets of
Drawings, and to the figures and letters marked thereon (that is to say):-
:-
On Sheet 1, Figure 1 is an elevation in section of a marine steam boiler
constructed according to my Invention; a is the outer shell of the boiler; b,
thefire-grate, and c, the roof of the fire-box which is formed of semi-elliptical
plates rivetted together at their edges, thereby producing a corrugated surface
against which the products of combustion impinge; these corrugations give a
larger heating surface to the fire-box and increase its strength; they also prevent
the adhesion of sediment as the expansion and contraction of the plates
loosen the scale and allows the water to have free access to the plates, conse-
quently the fuel being most advantageously applied is greatly economized.
Beyond the fire-grate b is the bridge d, over which the products of combustion
pass to the down flue e, then through the tubes f forming the multitubular
part of the boiler, and then into the chamber g which communicates by means
of the flue h with the chimney or funnel. Under the bridge d I insert a few
short tubes to admit air into the down flue e for the purpose of igniting the
inflammable gases passing over the bridge d, or a regulating damper d³, as
shewn in Figure 1, instead of the tubes d. The fluej near the bridge is only
opened when the fires are just ignited, but if owing to the leaking of the vessel
the water should come in and close the lower flue h, the flue j may be
opened so as to keep the engines going until the water rises in the vessel
sufficiently to extinguish the fires. The grate bar m is shewn in about the
position of the fire-grates in marine boilers of the ordinary construction, and
the grate bar 6 above it indicates the level of the fire-grate in my improved
boiler; the advantages of keeping the grate so much above the ordinary
level are apparent.
Figure 2 is a section of another of my improved marine boilers; in this

page_text: instance the roof of the fire-box is made of corrugated plates o stayed
longitudinally and vertically, and the water partitions n, shewn in section in
Figure 3, are placed in the down flue e to absorb a portion of the heat from
the products of combustion in passing to the up and down flues l, which are
formed by the water partitions o, projecting downwards from the central portion
of the boiler, and the partitions p projecting upwards from the lower part of
the boiler. The chamber g and the flues h and j are similar to those above
described in reference to Figure 1; in this improved boiler the outer side of
the chamber g is formed by the water partition q, and consequently all the flues
and lower portions of the boiler are perfectly water-tight, so that in case of the
leaking of the vessel the boiler may be kept in full work until the water rises
to the level of the fire-grate b. In both the marine boilers shewn in Figures
1 and 2 the fire is applied near to the surface of the water, and consequently
in the most advantageous position for rapidly generating steam; the ashes
and cinders are or may be collected in the buckets r, and the direction of
the products of combustion is indicated by the arrows.
Figure 4 is an elevation, and Figure 5 a plan, both in section, of a single
vertical boiler for stationary engines; a is the shell or outer casing; b, the fire-
grate, and c, the fire-box; t is a large pipe or tube which is kept full of water,
the communication between the water space surrounding the fire-box being
effected by the branch pipes t; to the outside of the tube t, and to the
inside of the fire-box are rivetted T or angle iron bars to hold in position
the fire-clay or other slabs 2, shewn in Figure 5; these slabs and the tube t
form the partition to separate the up draft from the down draft, and the
fire-clay of the slabs when red hot ignites the smoke, and effectually
consumes it before it arrives at the flue u which is in communication with
the chimney.
Figure 6 is an elevation, and Figure 7 a plan in section of the half of one
of my improved vertical boilers with two fire-grates; a is the outer shell or
casing; b, b, the fire-grates; c, the fire-box which is divided in the centre by
the two water partitions w, w, the space between which forms the down
flue; the upper end of the partitions w is partially closed by the perforated
fire clay top w¹, the object of which is to iguite the inflammable gases, and
to prevent the passage of smoke into the down draught flue. At the
bottom of the down flue are placed the pipes v through which the feed water
passes, and is thus partially heated in passing to the boiler.
Figure 8 is an elevation of the upper part of my improved compound
vertical steam boiler suitable for land or marine purposes; Figure 9 is a plan
of the same; these boilers are formed of four boilers similar to the one shewn

page_text: in Figures 4 and 5, the down flues being united below into the central flue
lending to the chimney or funnel. Although I have shewn four boilers united
in the Drawing I do not intend to limit myself to this number, as a greater
or less number may be used, and each portion of the boiler may be shut off
from or connected to the main flue x in case of repairs or for cleaning. The
various portions of this compound boiler being similar any portion may be
removed, and a spare one kept for the purpose put in its place when repairs
are necessary. I wish to remark that the boilers shewn in Figures 6 and 7
may also be grouped together to form a compound boiler as shewn in Figures
8 and 9.
Figure 10 is a section of a cylindrical horizontal boiler with my improve.
ments applied thereto; the roof of the fire-box is made in the manner
described in reference to Figure 1, and to the lower part of the internal flue
forming the continuation of the fire-box is rivetted the curved plate y; the
plates of the flue are perforated opposite this curved plate and the feed water
is pumped into the channel formed by the curved plate; the feed water is thus
distributed uniformly in the boiler. The end of the curved plate y is connected
to the supply pipes z, see Figure 11, passing through a portion of the flue, and
the feed water is thus heated in passing to the boiler. The dotted lines in
Figure 10 represent the heating pipes formed in a coil.
In Figure 12 I have shewn another modification of my improvements in
longitudinal cylindrical boilers; in this instance the corrugated roof c of the
fire-box is similar to that shewn in Figure 2, and to the lower part of the
boiler is rivetted the inverted Barlow's railway rail or other trough iron a² to
The pipes z for
form a channel for the easier distribution of the feed water.
the feed water are curved as shewn in Figure 13 to increase the surface
exposed to the heat of the flue.
On Sheet 2, Figure 14 is a longitudinal section, and Figure 15 a transverse
section of a cylindrical boiler constructed or altered according to my improve-
ments. In order to reduce the steam space and to prevent the condensation
which takes place in very long boilers of the ordinary construction, I
cause the portion of the boiler beyond the bridge to slope downwards either
by cutting the shell a and the flues in two, and piecing them up again at
the required angle, or in any other way; by this means the water entirely fills
the lower part of the boiler, and the steam dome is placed immediately over
the fire-grate b, or where the heat is the greatest. The pipes z for heating
the feed water are placed in the flue e, and as these pipes are connected to
the upper and lower side of the flue there will be a constant circulation in
the food water pipes.

page_text: Figure 16 is a section of a modification of this part of my Invention; in
this case the lower portion of the boiler instead of sloping downwards, as shewn
in Figure 14, is kept parallel with but on a lower level than the upper portion,
and in making new boilers of this description I prefer to make the lower part
of smaller diameter than the upper part, as shewn by the dotted line a², so
that there may less depth of water to heat, and sufficient space for the
steam above the fire-grate b. The bent tube ¹ is to cause the water to
circulate from the lower to the upper part of the boiler.
Figures 17 and 18 are two sections of another of my improved boilers.
This boiler is supposed to be made out of an ordinary double-flued boiler
cut in two and joined together again with the parts one above another,
and with the flues connected, so as to leave a water space between the flues
and the ends of the boiler; the two flues e unite in a double flue marked e',
which is provided with a midfeather or water space e². At the bottom of
the boiler is fixed a channel piece a² to collect the sediment and to
distribute the feed water.
Figures 19 and 20 are two views of another of my improved boilers. The
lower portion of this boiler is at right angles to the upper portion, and is
contained in a chamber or pit of fire-brick; the products of combustion on
leaving the flue e surround the lower part of the boiler and escape to the
chimney by the flue e³; in this boiler the fire-brick bridge d rests upon a
hollow perforated cast-iron chamber d³, within which is the sliding wedge
block d²; this block is now shewn open to admit air behind the bridge, and it
can be closed from the front of the boiler by the handle and rod shewn in
the Drawing. Instead of the tubes z a central pipe z³ with radiating branches,
as shewn in Figure 20, may be used.
Figure 21 is a section of a cylindrical boiler a with two smaller boilers as
and a connected to the larger one by conical tubes in the ordinary manner of
a Woolf's French boiler; the fire-grate bis placed under the upper portion a
and the products of combustion after passing under the portion a are brought
back along the flue surrounding the portion a5, and then into the flue of the
portion a. By placing the fire-grate 6 immediately under the upper portion
of the boiler the fire is brought in the most advantageous position for
generating steam. A compound boiler on this principle may be constructed
by placing two or more boilers together and applying the fire at right
angles to the boilers.
Figure 22 is a section of a compound boiler with the roof c of the fire-box
corrugated, as shewn in Figure 2, and with a corrugated plate c¹ placed below
the fire-grate b; the products of combustion after passing through the flue in

page_text: the boiler a are taken through the flue of the annular boiler a³, and then
through the multitubular portion a4 to the chimney.
Figure 23 is a section through a compound boiler very similar to that
shewn in Figure 22, but with the corrugations over the fire-box like those
shewn in Figure 1, and the corrugations c¹ are parallel to those of the
roof c; in this arrangement the annular boiler a³ has internal tubes to
increase the heating surface.
Figure 24 is a section of a boiler suitable for a locomotive engine or
portable steam engine; in this view both the lower portions of the boiler
are multitubular.
Figure 25 is a section of a retort boiler to which my present improve-
ments are applied; the tubes s are for heating the feed water, and the bridge d
is made with slots or openings to admit air when the damper d' is opened.
Figures 26, 27, and 28, represent various arrangements of pipes z for heating
the feed water placed within the flue leading from the boiler to the chimney.
Figure 29 represents a plan, and Figure 30 an elevation, partly in section, and
Figure 31 a section of my improvements in the construction of pans or other
vessels for the evaporation of saline or other fluids; the lower part of the pan
or vessel is corrugated, not only to expose a greater surface to the action of
the heat, but also to prevent the adhesion of saline or other deposit; these
corrugated pans are so much stronger than pans of the usual form that the
metal plates may be much thinner than heretofore, consequently the vibration
caused by striking them with a wooden mallet will loosen any sediment that
might adhere to the inside, and the pecking with steel-nosed hammers now
requisite to remove the scale or deposit, which is very injurious to the pans, is
avoided. In Figure 29 it will be seen that the corrugations marked A are at
right angles to the fire, and those marked B are in line with the fire. The
evaporating pans may be heated by the direct application of the products of
combustion from a fire, or by hot water or steam. In Figure 30 I have
shewn the pans placed above the drying chambers B₁ in which salt or other
substances may be dried and stored; B2 is a pair of iron doors to close the
chambers; Figure 31 is a section of the pans and furnaces under them,
shewing the interior of the store chambers B' and the columns B³ to support
the upper works. In all cases for generating steam and for evaporating
fluids the corrugations may be made at right angles to the passage of the
products of combustion, or in line therewith.
On Sheet 3, Figure 32 is a sectional elevation on an enlarged scale, and
Figure 33 a plan of an evaporating pan for saline or other Luids constructed
according to a modification of my improvements; B is the pan containing the

page_text: fluid to be heated or evaporated; this pan fits in the vessel D containing
water and steam. The fire-grate b is placed within the flue e pa ssing through
the vessel D, the water in which is kept in circulation by means of the coil of
pipes z, the smaller end of the coil being in communication with the lower
part of the boiler, and the larger end of the coil being connected to the upper
and lower parts of the boiler; the feed pipe z¹ is connected to the coil z. The
man-hole C may be placed at one side, as shewn, or at one end of the vessel D.
The products of combustion after passing through the flue e are conveyed
along one side of the vessel D and return at the other side. A regulating
valve d² similar to that shewn in Figure 1*, Sheet 1, is placed in the end flue,
as shewn in Fig. 35, or in the side flue, as shewn in Fig. 33, to admit air when
required to assist in consuming the smoke and inflammable gases; or the
products of combustion after leaving the flue e may be conveyed downwards,
as in Figures 1 and 2 of Sheet 1, under the vessel D into a flue formed by
the inner sides of the walls P, and then branch right and left into the outer
flues, which may be carried above the level of the water in the vessel D to
increase the heat, or they may be kept below the level of the water when
extra heat is not required; or the fire-box may have a corrugated roof, as
dotted and shewn in Fig. 23, or as otherwise described.
Figures 34 and 35 represent a modification of my Invention; in this
arrangement the lower part of the pan B is surrounded by a steam jacket F,
which is supplied with steam from the boiler D in which is the flue e, con-
taining the fire-grate 6 and the water tubes z, placed longitudinally. As the
water and steam spaces are too small to admit a workman one end of the
apparatus must be bolted on, and no man-hole is required. The flues and air
valve may be made as described in Figure 32, or otherwise. In Figs. 32
and 34 the upper portion of the apparatus is made in the manner described
in reference to the salt or evaporating pans, and the lower part is constructed
according to my improvements in generating steam.
Figure 36 represents a series of five pans which are heated according to
my improvements; the centre pan B is placed above and between the two
boilers D, which are united by the water chamber G; the steam from the
boilers passes into the jacket F of the pan B, and thence by means of the
pipes H into the jackets of the four smaller pans B. The products of com-
bustion after passing through the flues e unite together and pass over the
water chamber G, and then under it, or vice versa. It is evident that any
number of pans may be heated in the same manner.
Figure 37 is a section of another of my improved apparatus; the steam
from the boiler Dis conveyed into the steam chest I containing the corrugated

page_text: evaporating pans A, and into the steam jackets surrounding the pan B, B.
The circulation in the boiler is kept up.by the diagonal sets of pipes z, and
the feed water is heated in the sets of pipes z¹ placed in the flue under the
boiler. The boiler is supported by the beams R, R, which are protected.by
fire-clay saddles, and the man-holes S are to give access to the flue e; these
man-holes are covered with blocks of fire-clay.
Figures 38 and 39 represent two views of a cylindrical boiler wih a water
tube t similar to that shewn in Figures 4 and 5 of Sheet 1. In the flue e the
tube t is connected near the bridge to the lower part of the boiler, and near
the end to the upper and lower parts of the boiler, thereby causing a cir-
culation in the water as produced by the pipes z, above described; the
interior of the fluee and the exterior of the tube t are cleaned by the brush L,
which is moved to and fro occasionally by hand, or otherwise.
Figure 40 represents a modification of the improved marine boiler shewn
in Figures 1 and 2; in this boiler the heating surface is increased, and the
circulation promoted by the two sets of tubes M and N placed in the flue e.
The bridge d is made to contain water, and it is connected to the corrugated
roof c by pipes d².
Having thus stated the nature of my Invention, and described several
modes of performing the same, I declare that I claim,―
First, making the roofs of the fire-boxes of steam boilers and the under
side of evaporatng pans with corrugations, in the manner and for the
purposes described.
Secondly, the general arrangements of the parts of marine steam boilers,
as described and shewn in Figures 1, 2, 3, and 40.
Thirdly, the application of slabs and blocks of fire-clay to land boilers,
as shewn and described in reference to Figures 4, 5, 6, 7, 8, and 9.
Fourthly, the application of a large water tube in steam boilers, as shewn
and described in reference to Figures 4, 5, 9, 38, and 39.
Fifthly, the combination of one or more upright boilers to form one
compound boiler, as shewn and described in reference to Figures 8 and 9.
Sixthly, the application of a Barlow's rail or other trough iron to boilers, as
shewn in reference to Figures 12 and 18.
Seventhly, the application of pipes inside of the internal flues of boilers
to heat the feed water, and to promote self-acting circulation in the water
when the feed pumps are not at work, as shewn and described.
Eighthly, reducing the space for steam in steam boilers, and thereby
preventing condensation, as shewn and described in reference to Figures 14
to 20 inclusive.

page_text: Ninthly, placing the fire grate immediately below the upper portion of a
Woolf's French boiler, as shewn and described in reference to Figure 21.
Tenthly, the improved compound boilers shewn in Figures 22, 23, and 24,
in which the products of combustion are applied near the surface of the
water, and afterwards taken downwards.
Eleventhly, the general arrangement of the retort boiler and water heaters,
as shewn and described in reference to Figure 25.
Twelfthly, the arrangements of feed water pipes in the flues outside the
boilers, as shewn in Figures 26, 27, and 28.
Thirteenthly, the general arrangement of salt and other evaporating
pans, shewn and described in reference to Figures 29, 30, and 31.
Fourteenthly, the general arrangement of evaporating pans, as shewn and
described in reference to Figures 32 to 37 inclusive, and the modes of
heating them.
In witness whereof, I, the said Thomas Dunn, have hereto set my
hand and seal, this Twenty-seventh day of August, One thousand
eight hundred and sixty-seven.
THOMAS DUNN. (L.B.)