Improvements in Water Tube Boilers.
Year: 1899

page_text: Improvements in Water Tube Boilers.
I, Jons EDWARD THORNYCROFT, of Homefield, Chiswick, in the County of
Middlesex, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention has reference to water tube boilers of the kind wherein
water is caused to pass through a number of pairs of water tubes that are
arranged to extend from front to back of the boiler over a fire grate or grates
and the two tubes of each pair are inclined towards one another, as seen from
either side of the boiler, and also to a horizontal plane, and have their converg-
ing ends connected together, as for example through a junction box, and their
diverging ends connected at different levels to water supply and delivery cham-
bers in such manner that separate streams of water will flow simultaneously
through all the pairs of tubes from the supply to the delivery chambers.
In a steam boiler of the kind referred to according to this invention, the
diverging ends of the two tubes of each pair of tubes are connected to a tube
plate forming the rear wall of a water box that is connected at the top to one
or more steam and water vessels and is provided with one or more internal
division plates that divides or divide its interior into compartments one or
some of which is or are common to the lower ends of the several pairs of
tubes and constitutes or constitute a water downtake chamber or chambers, and
the other or others of which is or are common to the upper ends of the several
pairs of tubes and constitutes or constitute a water and steam uptake chamber or
chambers the arrangement being such that water will flow from the downtake
chamber or chambers simultaneously to the lower ends of all the pairs of tubes
and water and steam will flow from the upper ends of all the pairs of tubes into
the uptake chamber or chambers and thence to the steam and water vessel or
vessels wherein the steam will be separated from the water which will return
to the downtake chamber or chambers and again flow through the pairs of tubes.
In one arrangement of boiler of the kind referred to, the water box is pro-
vided with a division plate arranged more or less parallel to the front and rear
walls of the box and having its lower end extending down preferably to a line
just below the upper ends of the lowest pairs of tubes where it is bent inwards
towards the tube plate so as to divide the water box into two compartments one
of which, the outer, forms a down take chamber and the other, an uptake chamber.
The division plate is formed with holes arranged opposite to but usually larger
than the holes in that portion of the tube plate opposite which it extends. The
outer wall of the water box is formed with holes that may correspond in number
and position to but are usually larger than those in the tube plate or fewer
holes of larger size may be used if desired, each adapted for gaining access to
several tubes.
These holes are normally closed by suitable stoppers. Where the holes are
pitched near together, each of them may be closed by a cover plate held against
the outer side of the said wall by suitable means such as a bolt and cross bar, or

page_text: a tee headed bolt, the cross bar or the head of the tee-headed bolt, bridging over
the inuer end of the hole, and the shank of the bolt extending through the cover
plate and being provided on its outer side with a nut. When the holes are
pitched farther apart, they may each be of oval shape and be closed by an oval
cover plate of larger size inserted through the hole and held against the inner
edge thereof by a bolt that passes through the cover plate and an external cross
bar bridging over the outer end of the hole and is provided with a nut. This
bolt may if preferred be made in one piece with the inner cover plate.
In order to keep the two chambers formed within the water box by the
division plate separate so that water cannot flow from one to the other except
through the water tubes but so that it can How freely from the downtake chamber
to the lower tube of each pair of tubes and can flow freely from the upper tube
of each pair of tubes into the uptake chamber, each hole in the division plate
that is opposite the open end of the lower tube of each pair of water tubes is
fitted with a short removable tube (hereinafter called for distinction a guide
tube) that extends across the uptake chamber and enters the expanded open end
of the corresponding lower water tube, and each of the holes in the livision
plate that is opposite the upper or outlet end of a pair of water tubes is closed by
a removable stopper. Each guide tube, which is preferably of conical or
conoidal shape, may also extend across the downtake chamber and rest at its
outer end in the corresponding hole in the front wall of the water box, large
holes or openings being formed through that portion of the guide tube which
crosses the downtake chamber so as to allow of water freely Howing from that
chamber to the cross tube and thence to the lower tube of a pair of water tubes.
Each stopper may conveniently be a tube having a closed end and formed with
large oppositely arranged holes or openings through its wall, such tubular stopper
being arranged to extend across the downtake chamber with its closed end
fitting the hole in the division plate and its open end fitting the corresponding
hole in the front wall of the water box, the two holes in such tubular stopper
being arranged to come one over the other so as to allow of water passing freely
through them.
The front and rear sides of the water box are connected together by numerous
stays that extend through holes in the division plate and may advantageously be
made hollow so as to allow of jets of steam being blown at intervals into the
combustion chamber or space traversed by the water tubes, for the purpose
of cleaning the exteriors of such tubes. The hollow stays may also serve to
admit of the entry of air from outside of the boiler to the said combustion
chamber or space, and also to allow of the escape of water from the box in the
event of fracture of a stay, the issuing water serving to indicate such fracture.
The converging ends of each pair of water tubes are connected together by a
junction box, the two tubes extending away therefrom in such directions that
they diverge from one another vertically, one being inclined downward and the
other upward and each with its axis in a separate vertical plane. To admit of
access being gained to the junction box for securing the tube ends therein it is
or may be formed at the rear side with holes normally closed by stoppers.
In order that the two tubes of each pair of tubes shall, as seen in plan,
apparently be near together sideways and so prevent an unobstructed vertical
passage being formed between the two tubes of superimposd pairs of tubes, as
would be the case if the junction box conuerting each pair of tubes were
horizontal, the latter is inclined to the sides of the boiler, or to the planes con-
taining the axis of the two tubes.
Each water tube is or may advantageously be curved in the direction of its
length, the curvature being such that the lower tube of each pair is convex on
the side towards the fire and the upper tube of each pair is concave on the side
towards the fire. By this arrangement I obviate the effects of the unequal
expansion of the tubes due to the lower tube of each pair being exposed to
greater heat than the upper tube, riz. the tendency of the upper tube to be with-

page_text: drawn from the water box and junction box to which it is connected, and the
tendency of the lower tube to be forced into the water and junction boxes. The
bending of the tubes also enables their forward ends to be arranged at right
angles to the tube plate in which they are secured, and also to facilitato the
withdrawal of the tubes when the boiler is used in a confined situation, as in
the stoke-hold of a ship.
The water tubes, and also it may be the water box are enclosed in a suitable
casing above a fire grate the water box being suitably supported at the front
of the boiler, and the several junction boxes being arranged one above the other
and above a rear wall at the back of the fire grate. The boiler casing, when
enclosing the water box, is provided with a door or doors to admit of ready access
being gained to such water box. Above the water tubes the interior of the
casing communicates with the lower end of a chimney or uptake which is or
may be provided with a deflecting device or devices to facilitate the distribution
of the flame and hot gases amongst the water tubes. The lower portion of the
chimney or uptake may also be provided with a feed water heater as heretofore.
The upper end of the water box is in free communication with a transverse
steam and water vessel which may be of cylindrical shape and be arranged at
the front of the boiler and across or along the top of the water box to the flanged
upper end of which it may be directly secured. The upper end of the division
plate in the water box is or may be extended upward through the bottom of
the steam and water vessel in order to better separate the ascending and descend-
ing streams of water and promote good water circulation. The water box is or
may be provided with a blow off cock so that all the pairs of tubes may be simul-
taneously and quickly emptied of water when desired.
Two or more water boxes of the kind mentioned, but of less width, may, in
Fome cases, be used instead of a single water box common to all the water tubes.
In some cases, one or more external downtake pipes may connect the steam
and water vessel to the lower end of the water box or of each such box in
addition to or in lieu of the connection between the bottom of the steam and
water vessel and the top of the downtake chamber within the water box. When
two or more water boxes are used, such a downtake pipe may be arranged be-
tween and connected to two adjacent water boxes, or each adjacent pair of water
boxes.
In some cases two or more longitudinally arranged steam and water vessels
may be employed, such vessels being suitably connected to the closed top of
the water box or boxes by tubular connections.
In a modified arrangement, the water box, or each water box, instead of being
divided into two wide transversely arranged compartments or chambers by a
single transversely arranged division plate, is divided by vertical division plates
or channels extending from front to back of the box into a number of alternately
arranged vertical uptake and downtake chambers, each downtake being located
in front of and common to the lower ends of the lower tubes of superimposed
pairs of tubes, and each uptake being located in front of and common to the
upper ends of the upper tubes of superimposed pairs of tubes. The downtake
chambers may be connected to a common outlet provided with a blow off valve,
r each downtake chamber may have a separate blow off valve. In this arrange-
ment of boiler, the guide tubes and stoppers employed in the arrangement first
herein described are dispensed with.
Datad this 9th dox of November 1899
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.

page_text: I, JOHN EDWARD THORNYCROFT, of Homefield, Chiswick, in the County of
Middlesex, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:--
This invention has reference to water tube boilers of the kind wherein
water is caused to pass through a number of pairs of water tubes that are
arranged to extend from front to back of the boiler over a fire grate or grates
and the two tubes of each pair are inclined towards one another, as soen from
either side of the boiler, and also to a horizontal plane and have their converg-
ing ends connected together, as for example through a junction box, and their
diverging ends connected at different levels to water supply and delivery cham-
bers in such manner that separate streams of water will flow simultaneously
through all the pairs of tubes from the supply to the delivery chambers.
In a steam boiler of the kind referred to according to this invention, the
diverging ends of the two tubes of each pair of tubes are connected to a tube
plate forming the rear wall of a water box that is connected at the top to one
or more steam and water vessels and is provided with one or more internal
division plates that divides or divide its interior into compartments one or'
some of which is or are common to the lower ends of the several pairs of
tubes and constitutes or constitute a water downtake chamber or chambers and
the other or others of which is or are common to the upper ends of the several
pairs of tubes and constitutes or constitute a water and steam uptake chamber or
chambers the arrangement being such that water will flow from the downtake
chamber or chambers simultaneously to the lower ends of all the pairs of tubes
and water and steam will flow from the upper ends of all the pairs of tubes into
the uptake chamber or chambera and thence to the steam and water vessel or
vessels wherein the steam will be separated from the water which will return
to the downtake chamber or chambers and again flow through the pairs of tubes.
Referring to the accompanying illustrative drawings,
Fig. 1 shows partly in front elevation, and partly in section on the line A-A
Fig. 2, one construction of steam boiler according to this invention.
Fig. 2 is a cross section on the line B--B of Fig. 1.
Fig. 2 is a detail view.
Fig. 3 is a longitudinal section corresponding to the line CC of Fig. 1, but
drawn to a larger scale, showing part of a water box with the inlet end of one
of the water tubes connected thereto, a division plate in said box, a guide tube
for leading water to said tube end, and means for closing the hole in the front
wall of the water box. Fig. 4 is a similar view to Fig. 3 but taken on the
line DD of Fig. 1 and showing part of the water box with the outlet end of
one of the water tubes connected thereto, the division plate, a stopper arranged
opposite the said tube end and in the division plate, and modified means for
closing the corresponding hole in the front wall of the water box. Fig. 5 is a
part longitudinal section, and Fig. 6 a part front elevation, showing another way
of closing the holes in the front wall of the water box.
a and bare the two inclined tubes constituting a pair of water tubes, of
which there are many, arranged one above the other and sideways of one an-
other, the converging end of each pair of tubes being connected to a junction box c
common to them.
In a steam boiler of the kind referred to according to this invention, the
diverging ends d and e of the two tubes a and b of each pair of tubes are con-

page_text: nected to a tube plate f forming the rear wall of a water box that is connected
at the top to a steam and water vessel g. The water box is provided with a
transversely arranged division plate arranged between the rear and front
walls and respectively of the box and having its lower end extending down
preferably to a line just below the upper ends of the lowest pairs of tubes a
and b, where it is bent inwards, as shown in dotted lines at k in Fig. 2, towards
the tube plate f so as to divide the water box into two compartments m and ",
one of which, rit. m forms a downtake chamber common to the lower inlet ends d
of the several pairs of tubes, & the other, riz n, forms an uptake chamber common
to the upper outlet ends e of the several pairs of tubes. The division plate h
is formed with holes o arranged opposite to but usually larger than the holes
in that portion of the tube plate opposite which it extends. The outer wall i
of the water box is also formed with holes that may correspond in number and
Tosition to but are usually larger than those in the tube plate f; or fewer holes
of larger size may be used if desired, each adapted for gaining access to soveral
tubes.
The holes in the front plate are normally closed by suitable stoppers. Where
the holes are pitched near together, as at the central portion of the front wall,
and when there are as many holes in such wall as in the tube plate f, each bole
may be closed by a cover plate (see Figs. 3 and 4) held against the outer side of
the said wall by suitable means, such as a bolts and cross bar (Fig. 4), or it may
be a tee headed bolts (Fig. 3), the cross bar, or the head of the tee-headed bolt,
as the case may be, bridging over the inner end of the hole, and the shank of the
bolt extending through the cover plater and being provided on its outer side
with a cap nut u. When the holes are pitched farther apart, as at the upper
and lower portions of the said front plate, they may each be of oval shape (see
Figs. 5 and 6) may be closed by an oval cover plate, of larger area than the hole
inserted through the hole and held against the inner edge portion thereof by a
bolt that passes through the said cover plate and an external cross bar r,
bridging over the outer end of the hole, and is provided with a nut z. The bolt we
may be made in one piece with the cover plate r
In order to keep the two chambers m and n formed within the water box by
the division plate h separate, so that water cannot flow from one to the other
except through the water tubes but so that it can flow freely from the down-
take chamber m to the lower tube a of each part of tubes and can flow freely from
the upper tube of each pair of tubes into the uptake chamber n, each hole o in the
division plate that is opposite the open end of the lower tube a of each pair of
water tubes a and b is fitted with a short removable tube 1 (hereinafter called
for distinction a guide tube) that extends across the uptake chamber and
enters the expanded open end d of the corresponding lower water tube a, and
cach of the holes o in the division plate that is opposite the upper or outlet end
of the upper tube of a pair of water tubes is closed by a removable stopper 2.
Each guide tube 1, which is preferably of conical or conoidal shape (see Fig. 3),
may also extend across the downtake chamber m and rest at its outer end in
the corresponding hole in the front wall of the water box, large holes or
openings 3 being formed through that portion of the guide tube 1 that crosses
the downtake chamber m so as to allow of water freely flowing from that cham-
ber to the cross tube, as indicated by the arrow X, and thence to the lower
tube a of a pair of water tubes. Each stopper 2 may, as shown in Fig. 4, con-
veniently be a tube having a closed inner end and formed with large oppositely
arranged holes or openings 4 through its wall, such tubular stopper being
arranged to extend across the downtake chamber with its closed end fitting the
hole o in the division plate and its open end fitting the corresponding hole p
in the front wall i of the water box, the two holes or openings in such tubular
stopper being arranged to come one over the other so as to allow of water passing
freely through them as indicated by the vertical arrow Y.
By the construction described it will be seen that water will flow from the

page_text: downtake chamber m simultaneously to the lower ends of all the pairs of
tubes a and b, and water and steam will flow from the upper ends e of all the
pairs of tubes into the uptake chamber and thence to the steam and water
vessel wherein the steam will be separated from the water which will return
to the downtake chamber m and again flow through the pairs of tubes a and b.
The front and rear sides and f of the water box are connected together by
numerous stays 5, of which one only is shown in Fig. 3. These stays extend
through holes in the division plate h and may advantageously be made hollow,
as shown, so as to allow of jets of steam being blown at intervals in to the com-
bustion chamber or space 6 traversed by the water tubes a and b, for the pur-
pose of cleaning the exteriors of such tubes. The hollow stays may also serve to
admit of the entry of air from outside of the boiler to the said combustion
chamber or space, and also to allow of the escape of water from the box in the
event of fracture of a stay, the issuing water serving to indicate such fracture.
The converging ends of each pair of water tubes a and b are, as hereinbefore
stated, connected together by a junction box e, (Fig. 2) the two tubes extending
away therefrom in such directions that they diverge from one another vertically,
one being inclined downward and the other upward and each with its axis in
a separate vertical plane. To admit of access being gained to the junction box
so as to allow of the tubes being easily fixed in the junction boxes, ench junction
box is or may, as usual, be formed at the rear side with boles normally closed
by stoppers 7.
In order that the two tubes a and b of each pair of tubes shall, as seen in
plan, apparently he near together sideways and so prevent an unobstructed
vertical passage being formed between the two tubes of superimposed pairs of
tubes as would be the case if the junction box c connecting each pair of tubes
were horizontal, each junction box is inclined to the sides of the boiler, or to
the planes containing the axes of the two tubes, as shown in dotted lines in Fig. 1.
Only a few of the junction boxes so arranged are shown in the said figure
in order not to complicate the same.
Each water tube and bis or may advantageously be curved in the direction
of its length, the curvature being such that the lower tube a of each pair is
convex on the side towards the fire, and the upper tube of each pair is concave
on the side towards the fire. By this arrangement I obviate the effects of the
unequal expansion of the tubes due to the lower tube of each pair being exposed
to greater heat than the upper tube, riz., the tendency of the upper tube to be
withdrawn from the tube plate f and junction box c to which it is connected,
and the tendency of the lower tube to be forced into the said tube plate and
junction box. The bending of the tubes also enables their forward ends to he
arranged at right angles to the tube plate f in which they are secured, and
facilitates the withdrawal of the tubes through the water box when the boiler
is used in a confined situation, as in the stoke-hold of a ship.
The water tubes a and b, and also it may be the water box i-f, are enclosed in
a suitable casing 8 above a fire grate 9, the water box being suitably supported
at the front of the boiler by the casing and the severel junction boxes being
arranged one above the other and above a rear wall 10 at the back of the fire
grate. The boiler casing 8, when enclosing the water box, is provided with a
door or doors 11 to admit of ready access being gained to such water box. Above
the water tubes the interior of the casing communicates with the lower end of a
chimney or uptake 12 which is or may be provided with a deflecting plate 13,
or deflecting slab 13 to facilitate the distribution of the flame and hot gases
amongst the water tube. The lower portion of the chimney or uptake may also
be provided with a feed water heater 14 as shown in Fig. 7, which is a similar
view to the upper part of Fig. 2.
The upper end of the water box if is in free communication with the steam
and water vessel 9, which may, as shown, he of cylindrical shape and be arranged
transversely at the front of the boiler and along the top of the water box to the

page_text: flanged upper end of which it may be directly secured. The upper end of the
division plate in the water box is or may be extended upward through the
bottom of the steam and water vessel, as shown, in order to better separate the
ascending and descending streams of water and promote good water circulation.
The water box is or may be provided with a blow of cock 15 so that all the pairs
of tubes may be simultaneously and quickly emptied of water when desired;
this is a feature of considerable practical importance as it allows of the boiler
being easily and quickly emptied when desired.
Two or more water boxes of the kind mentioned but of less width, may, in
some cases, be used instead of a single water box common to all the water tubes.
This modified construction will be understood from Fig. 1 if it be assumed that
the dotted line 16 shows the division between two adjacent water boxes.
In some cases, one or more external downtake pipes may connect the steam
and water vessel g to the lower end of the water box, or of each such box in
addition to or in lieu of the connection between the bottom of the steam and
water vessel and the top of the downtake chamber m within the water box, or
cuch water box. When two or more water boxes are used, such a downtake
pipe may be arranged between and connected to two adjacent water boxes, or
each adjacent pair of water boxes, as shown in Fig. 8, where m is an internal
downtake pipe arranged and connected as described.
In some cases two or more longitudinally arranged steam and water vessels g,
may be employed as shewn in Fig. 9, such vessels being suitably connected to
the closed top of the water box.
Fig. 10 is a horizontal section corresponding to the line -- of Fig. 1, but
showing a further modified arrangement wherein the water box if instead of
being divided into two wide transversely arranged compartments or chambers by
a single transversely arranged division plate, as in the arrangement shown in
Figs. 1 to 6 inclusive, is divided by vertical division plates 18, or channels 19,
extending from front to back of the box, into a number of alternately arranged
vertical downtake and uptake chambers m and respectively, ench downtake
chamber being located in front of and common to the lower ends of the
lower tubes a of superimposed pairs of tubes, and each uptake chamber a being
located in front of and common to the upper ends of the upper tubes b of super-
imposed pairs of tubes. The downtake chambers m may be connected to a
common outlet provided with a blow off valve, or each downtake chamber may
have a separate blow off valve. In this arrangement of boiler the guide tubes
and stoppers employed in the arrangement first herein described are dispensed
with.
Having now particularly described and ascertained the nature of the said
invention and in what mauner the same is to be performed I declare that what
I claim is:--
1. A steam generator of the kind herein referred to wherein the diverging
ends of the two tubes of each pair of water tubes are connected to a tube plate
forming one wall of a water box that is connected at the top to one or more
steam and water vessels and is provided with one or more internal division
plates that divides or divide its interior into separate compartments one or
Eome of which is or are common to the lower ends of the several pairs of water
tubes and constitutes or constitute a water downtake chamber or chambers and
the other or others of which is or are common to the upper ends of the several
pairs of tubes and constitutes or constitute a water and steam uptake chamber
or chambers, substantially as herein before described with reference to the draw-
ings.
2. A steam generator of the kind referred to in the preceding claim wherein
the water box is provided with a single division plate that divides the water
box into two chambers viz. an uptake chamber and a downlake chamber and is
formed with holes some of which are fitted with guide tubes that extend across

page_text: the uptake chamber from the open or inlet ends of the lower water tubes into
the downtake chamber and others are closed by removable stoppers, substantially
as described for the purpose specified.
3. A steam generator of the kind herein referred to wherein the diverging
ends of the pairs of water tubes are fixed in a common tube plate forming one
side of a water box conueeled at its upper end to a steam and water vessel and
the converging ends of each pair of said water tubes are connected together by
a junction box that is inclined to the horizontal, the arrangement being such
that the two tubes of the several pairs of tubes are in adjacent vertical rows
that are arranged so close together as to cause the hot gases to take a zig-zag
course between the tubes on their way to the chimney and prevent them passing
idly upward in vertical streams between adjacent rows of tubes, substantially as
described.
4. A water tube boller of the kind herein referred to wherein the two tubes
of each pair of water tubes are curved in the direction of their length, the curva-
ture being such that the lower tube of cach pair is convex on the side towards
the fire and the upper tube of each pair is concave on the side towards the fire,
substantially as described for the purpose specified.
5. The improved construction of water tube steam boiler hereinbefore described
with reference to and shewn in Figs. 1 to 6 inclusive, or modified according to
Fig. 7, or to Fig. 8, or to Fig. 9 or to Fig. 10 of the drawings annexed.
Dated this 24th day of July 1900.
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.