TRUVISIONAL OF MOLLIOUATION Improvements in Steam Boilers.
Year: 1894

page_text: Date of Application, 19th Apr., 1894
Complete Specification Left, 21st Jan., 1895-Accepted, 19th Apr., 1895
TRUVISIONAL OF MOLLIOUATION
Improvements in Steam Boilers.
I, THOMAS HERALD, of 18 St. Andrew Street, Dundee, in the County of
Forfar, Commission Agent, do hereby declare the nature of this invention to be as
follows:-
This invention has reference to an improved construction of steam boiler of the
water tube type designed to possess all the advantages of steam boilers of the
ordinary marine type without their disadvantages, and wherein the tube ends and
tube plates are so disposed as to be away from the zones of the most intense heat.
My improved water tube boiler comprises an upper longitudinal steam and water
vessel, or there may be more than one, that is connected with two or more longi-
tudinal lower vessels between which the fire grate or grates are placed by heating
tubes which are so bent and arranged as to forin at the front end of the boiler one
or more furnace chambers having close roofs with return flues above them, and at
the rear end, one or more combustion chambers that may be similar to those of an
ordinary marine boiler. The front of the boiler is or may be provided with a
smoke box in connection with the return flue or flues, the furnace chamber or
chambers being closed by a metal or other furnace front provided with a fire, door
or doors. The back of the boiler may be formed by a vertical water chamber
having flat stayed sides and connected with the upper water and steam vessel
(hereinafter called a separator) and with the lower water vessels; or the back may
be formed by a series of tubes fixed between the separator and the longitudinal
water vessels or between the separator and a transverse water chamber fitted
between the longitudinal ones, the interstices between the tubes being filled with
suitable refractory material.
The separator is preferably made of cylindrical form with projecting wings each
having preferably flat sides one of which forms a tube plate to which the upper
ends of the heating tubes are secured in any suitable way as by screwing or
expanding, whilst the other side or cover plate is provided with normally closed
cleaning holes corresponding with the holes in the tube plate so that access can be
readily obtained for fixing and cleaning the tubes. The longitudinal water vessels,
which may be connected with each other by horizontal stay tubes, are preferably
also made with flat sides like those of the separator wings.
The heating tubes forming the outermost or two outermost rows of tubes on each
side of the boiler are brought close together or touching each other after leaving
the tube plates so as to form the sides or shell of the boiler. These tubes may
advantageously be fixed in place by screwing a ferrule or gland into each of them
from the inside of the separator and water chamber to which they are to be
connected in which case the ends of the tubes may if desired be enlarged. The
other or inner tubes forming the sides and crowns of the furnaces and the return
flues, rise from the water vessels on each side of each furnace, cross over the latter
to the opposite side of the boiler and from thence, with one or more bends, pass to
the separator. These tubes at their intermediate portions diverge from each other
so that their surfaces will be more fully exposed to the flames and heated gases
than the end portions, and where a series crosses the corresponding one from the
other side over the furnaces, diaphragms of metal or other refractory material are
arranged extending where necessary, to the water vessels, thus separating the

page_text: furnaces, of which in one construction there are three, from the return flues, and
from each other. Similar diaphragms may also be employed to divide the flue so
that the flames and heated gases from each combustion chamber, when there are
more than one, can pass separately to the uptake.
Filling blocks are placed where the curvature of the tubes leave large openings
between the combustion chamber and the uptake.
In one arrangement there are two main groups of tubes arranged to cross
each other so as to form three furnace chambers each group comprising twelve
series of tubes which are so bent and arranged that near their junction with
the wings and water vessels they form six longitudinal rows of tubes, whilst
their intermediate portions form twelve longitudinal rows of tubes each composed
of tubes spaced apart in consequence of the crossing of the two groups. The
pairs of tubes composing the two groups may be arranged so close together as to
touch each other where they cross, but if a space equal in width to the diameter
of the tubes be left between each adjacent pair of tubes, it will be practicable by
removing the shell tube opposite such space, the filling blocks, and a portion of the
diaphragms, to take out and replace any tube without disturbing the others.
.
The combustion chamber or chambers may be provided with a series of heating
tubes. When there is only one such chamber the series of tubes therein may rise
from the water vessels and pass alternately to the right and left sides of the boiler
and thence to the separator, all or part of them passing under the cylindrical
lower portion of the separator so as to protect the same to some extent from direct
impact of the flames. When more than one combustion chamber is required, the
divisions between them may be formed by two rows of tubes fixed between the
separator and the water vessels and brought near together or touching each other,
other rows of tubes. being fitted in each chamber and running beside the
partitional ones at the sides but crossing each other at the top and bottom. Whether
one or more combustion chambers be formed, the spaces between the crossing
tubes at the bottom are preferably filled with refractory material, and the spaces
at the top may be wholly or partially so treated. At the front of the boiler, one
or more strong stay tubes may be fixed between the separator and one or some of
the water vessels, such tube or tubes serving to hold parts of the boiler firmly
together, and also as a downtake tube or tubes to convey water from the separator
to one or more of the water vessels. The stay tube or each such tube when more
than one are used, may have one or more short horizontal tubes passed through it,
so that its large diameter will not prevent the return flues from being readily
cleaned. The stay tube or tubes may be replaced by one or more struts. In
some cases, as in land boilers, the stay tube or tubes, or strut or struts, may be
dispensed with.
When a boiler according to my invention is constructed to be fired from both
ends, the back will become a central water space, or it may be omitted, the
combustion chamber or chambers being then made common to one or more furnaces
from each end.
To enable either of the heating tubes to be put out of action when necessary, I
provide opposite each of the open ends of each tube, a stopping device capable of
being operated from the exterior of the wing or water vessel to which the end of
the tube is connected so that it can be forced against and effectually close the end
of the tube. A stopping device suitable for this purpose comprises a plug or
stopper carried by a screw threaded spindle extending through the screw plug fitted
in each cleaning hole in the plate opposite the tube plate of each wing and water
vessel herein before referred to, a washer of suitable material, for example lead,
being fitted to each side of the plug or stopper so that the latter can be caused to
make a tight joint with the screw plug when in its inoperative position, and with
the end of the heating tube when moved into its operative position at which time a
screw cap is screwed over the outwardly projecting end of the spindle so as to form
with the aid of a washer, a fluid tight joint with the outer side of the screw plug
and thus prevent leakage of steam between the screw threads of the spindle and

page_text: screw plug. A stopping device of the kind mentioned may be used in water tube
boilers of various constructions for the purpose specified.
The boiler is provided with suitable seats preferably of sufficient height to render
the underside of the longitudinal water vessels readily accessible and which form
ash pits underneath the fire-grates, and also with a suitable casing and the usual
aids to safe and convenient working..
Improvements in Steam Boilers.
I, THOMAS HERALD, of 18 St. Andrews Street, in the City and County of
Dundee, Commission Agent, 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 an improved construction of steam boiler of the
water tube type which is designed to possess all the advantages of steam boilers of
the ordinary marine type without their disadvantages, and wherein the tube ends
and tube plates are so disposed as to be away from the zones of the most intense
heat.
And in order that the nature of my invention may be fully understood, I will
proceed to explain the same by aid of the accompanying illustrative drawings in
which,
Fig. 1 is a central longitudinal section of a water tube boiler constructed
according thereto, and
Figs. 2 and 3 are vertical cross sections thereof on the lines II, II and III, III
respectively of Fig. 1.
Fig. 4 is a corresponding section to Fig. 3 showing a modified arrangement.
Figs. 5 and 6 and Figs. 7 and 8 illustrate respectively two methods of arranging
the outermost or shell tubes and securing them to their tube plates, Figs. 5 and 7
being sections, and Figs. 6 and 8 corresponding plans.
Fig. 9 illustrates in section, devices for putting the heating tubes individually out
of action when desired.
Figs. 10 and 11 are sections, corresponding to Figs. 1 and 2 respectively,
illustrating a lighter construction of boiler according to this invention.
Fig. 12 shows alternative sections of the separator in the rear part of the
construction shown in Figs. 10 and 11.
The water tube boiler shown in Figs. 1, 2 and 3 comprises an upper longitudinal
steam and water vessel 1 (hereinafter called a separator) connected with four
longitudinal lower water vessels 2", 2, 2 and 2ª, between which the fire grates 3
are located, by heating tubes comprising several rows of internal tubes viz. 4, 4º,
to 15, 15 that connect the said separator and water vessels along a part only of the
length thereof, (Fig. 1) and two rows of external or shell tubes 16 and 17 that
connect the said separator and water vessels nearly throughout their length, the
said heating tubes being bent, crossed, and arranged as shown so as to form, at the
front end of the boiler, three furnace chambers 18, 18, and 18 having close roofs,
with a return flue 19 above them, and, at the rear end, a combustion chamber 20
that is somewhat similar to that of an ordinary marine boiler. The front of the
boiler is shown provided with a smoke box 21 in connection with the return flue 19,
and the front of the furnace chambers 18, 18, and 18° is closed by a metal or other

page_text: suitable furnace front 22 provided with fire doors 23. The back of the boiler may,
as shown in Fig. 1, be formed by a vertical water chamber 24 that has flat stayed
sides 24ª and 24 and is connected at the top with the separator 1 and at the bottom
with the lower water vessels 2ª, 2, 2º, and 24. The back of the boiler may,
however, consist of a wall of fire-brick or other suitable refractory material; or it
may be formed, in a manner that will be readily understood, by a series of tubes
connecting the separator either with the longitudinal water vessels 2*
2ª,
direct, or with a transverse water chamber fitted between and in communication
with the said longitudinal vessels, the interstices between the tubes being filled
with suitable refractory material.
The separator 1 is preferably made of cylindrical form, as shown, and provided
with projecting wings 25 and 25° each having preferably flat sides 26 and 27, of
which the lower ones, riz.: 26, form tube plates to which the upper ends of the
heating tubes 4 to 17 are secured in any suitable or convenient way, as by screwing
or expanding, or in the manner hereinafter described with reference to Figs. 5, 6, 7
and 8, whilst the other or cover plates 27 are provided with cleaning holes which
are normally closed by stoppers 27" and correspond to the holes for the tubes in the
opposite tube plates 26, so that access can be readily obtained for fixing and
cleaning the tubes. The interior of the separator 1 is connected with the interiors
of the wings 25 and 25" by a series of holes 1" that serve to provide ample passage
for steam and water to flow separately from the corresponding wing to the separator
so that the steam will not tend to take up any of the water, and the holes will not
materially reduce the strength of the separator. The neutral portions of the
separator between the cover plates 27 and the tube plates 26, in which the holes 1*
are formed, should be suitably strengthened, as for example by making the shell of
double thickness at these parts, as shown, to prevent their being deformed.
The longitudinal water vessels 2ª, 2, 2; and 2, which may be connected with
one another by horizontal stay tubes 28, are preferably also made with flat sides or
plates 29 and 30 like the separator wings 25 and 25°, the plates 30 being provided
with normally closed cleaning holes like the plates 27 and for a similar purpose.
As will be obvious however access can be gained to the separator wings and water
vessels for the purposes mentioned, otherwise than through the cleaning holes, as
for example, by making the plates 27 and 30 removable.
The heating tubes 16 and 17 forming the outermost row of tubes on each side of
the boiler, are brought close together or made to touch one another after leaving
the tube plates 26 and 29 of the separator wings and water vessels respectively, so
as to form the sides or shell of the boiler. These tubes may advantageously be
fixed in place by screwing a ferrule or gland 16 into each of them from the insides
of the tube plates 26 or 29 to which they are to be connected as shown with
reference to the tubes 16 in Figs. 5 and 6. In order to obviate the reduction of
the effective internal diameter of the tubes thereby entailed, the tubes may be
arranged to form two rows where they are secured to the tube plates and their ends
be enlarged as shown in Figs. 7 and 8, so that the internal diameters of the ferrules
cr glands 16 may be equal to those of the unenlarged portions of the tubes into
which they are screwed.
The other or inner tubes 4, 4* to 15, 15ª forming the sides and crowns of the
furnace chambers 18", 18%, and 18° and the return fluc 19, rise from the water
vessels 2ª . . 2ª (Fig. 2) on each side of each furnace chamber, cross over. the
latter toward the opposite side of the boiler, and then with one or more bends, pass
to the separator wings. These tubes diverge from each other at their intermediate
portions, as shown, so that their surfaces, or some of them, will be more fully
exposed to the flames and heated gases than their end portions. Upon the two
corresponding series of tubes 4 and 10 which extend over the furnace chambers and
cross each other as shown, diaphragms 31 of metal or other refractory material
are arranged so as to form close roots to the furnace chambers and separate them
from the return flue 19, which as will be seen, is located mainly between the furnace
chambers and the separator.

page_text: By arranging the heating tubes 4 to 15ª inclusive and diaphragms 31 in the
manner described and shown, the lower portions of the tubes are brought into a
position to be effectually heated by heat radiated from the mass of incandescent
fuel on the firegrate or grates as well as by flame from the said fuel, whilst their
upper portions are subjected to the heat of the flame and hot gases passing through
the horizontal return flue 19 in a direction at right angles to the tubes, whereby
the greatest possible heating effect is obtained. The diaphragms 31 may con-
veniently be formed of fire-clay tiles suitably shaped and fitted together, as shown
for example to a larger scale in Fig. 24, semi-circular recesses 31" being formed in
their abutting edges, where necessary, to permit of the passage therethrough, as
shown, of the other heating tubes into the furnace chambers. Where desired or
necessary, the diaphragms 31 may extend downwards to the water vessels 2ª 2",
as shown on the right hand of Fig. 2, so as to separate the furnace chambers 18ª, 18,
and 18" from one another in a longitudinal direction.
Filling blocks 19 are placed in the return flue 19, where, owing to the curvature
of the sinuous heating tubes, large openings or passages, not traversed by tubes, are
formed between the combustion chamber and the uptake 21. These filling blocks
may conveniently consist of light sheet-iron boxes faced with refractory material
where exposed to the direct impact of flame and hot gases. By providing a large
combustion chamber at the rear of the furnace, about equal in height to the furnaces
and return flue or flues as shown, flame is reverberated from the back of the boiler,
and the gases entering the combustion chamber are free to expand whereby their
more perfect combustion is ensured with the result that the return flue remains
clean for a longer time than would otherwise be the case. A combustion chamber
common to two or more furnace chambers, as shown, also aids combustion, and if
one or more furnaces enter the chamber at opposite sides, the flames etc. from one
furnace reverberate from those of the other, enabling a flat vertical surface between
the two sets of furnaces to be dispensed with.
In the arrangement shown in Figs. 1, 2, and 3, the heating tubes 4 to 15ª form
two main groups arranged to cross each other so as to form the three furnace
chambers 18, 18, and 18, one group consisting of the tubes 4, 4" to 9, 9, and the
other of the tubes 10, 10 to 15, 15. Each group thus comprises twelve series of
tubes which are so bent and arranged that near their junction with the wings and
the water vessels they form six longitudinal rows of tubes composed in the one
group of the tubes 4 and 4, 5, and 5", . . . and 9 and 9* respectively, and in the
other group of the tubes 10 and 10ª, 11 and 11ª, 15 and 15 respectively, whilst
their intermediate portions form twelve rows of tubes composed in the one group of
the tubes 4,4° .9, 9 respectively and in the other of the tubes 10, 10". . . 15, 15*
respectively, the tubes in each row being spaced apart in consequence of the
crossing of the two groups. In the example shown the holes in the tube plates 26
of the separator wings in which the heating tubes 4 . . 15* inclusive are secured,
are pitched diagonally so that a minimum width of tube plate can be used.
The several sets of tubes having their axes in parallel vertical planes, viz. sets
composed of the tubes 4 to 9, 10 to 15, 4 to 9, and 10 to 15", may be arranged so
close together as to touch each other where they cross. It is preferred however to
leave a space a
(Fig. 1) at least equal in width to the diameter of one of the tubes
between each set of tubes 10 to 15, commencing from the front of the generator,
and the adjacent set 4* to 9ª and between each set 10 to 15 and the next adjacent.
set 4 to 9; as by this means it is practicable, by removing a shell tube 16 or 17
opposite such a space, the lateral filling block 19 adjacent to such shell tube, and a
portion of the corresponding diaphragm or diaphragms 31, to take out and replace
any tube without disturbing the others.
The combustion chamber 20 may advantageously be provided with a series of
heating tubes 32, 32, 32, and 32 (see Fig. 3), which rise from the water
vessels 2ª, 20, 2, and 2d respectively and pass alternately to the right and left sides
of the boiler and thence to the separator wings, some, as shown, or all of such tubes

page_text: passing under the cylindrical lower portion of the separator 1 so as to protect the
same to some extent from direct impact of the flame.
When more than one combustion chamber is required, the divisions between
them may be formed by longitudinal rows of tubes, as shown in Fig. 4, which shows
three combustion chambers 20. In this case there are two divisions, one formed by
some of the tubes 32" and 32° and the other by some of the tubes 32° and 32ª, such
tubes being brought near together or made to touch one another along their
vertical, or approximately vertical, portions. Other rows of tubes, composed of the
remaining tubes 32", 32, 32, and 32 extend upward through the said chambers,
running beside the partitional and shell tubes but crossing one another at the top
and bottom as shown. Whether one or more combustion chambers be formed, the
spaces between the crossing tubes at the bottom thereof are preferably filled with
refractory material, and the spaces at the top may be wholly or partially so treated.
At the front of the boiler, two strong stay tubes 33 may be fixed between the
separator and the water vessels 2° and 2°, such tubes serving to hold parts of
the boiler firmly together, and also as downtake tubes to convey water from the
separator to the said water vessels. Each of the stay tubes 33 may have one or
more short horizontal tubes passed through it, longitudinally as regards the boiler,
so that the comparatively large diameter of the stay tube will not prevent the spaces
between the rows of tubes in the return flue 19 from being readily cleaned.
When a boiler according to my invention is constructed to be fired from both ends,
the vertical water chamber 24 will be centrally situated between the two combustion
chambers; or the said water chamber may be omitted, the combustion chamber or
chambers being then made common to one or more furnaces extending from each
end of the generator.
To enable any one of the heating tubes 4..... 17 to be readily put out of action
when necessary, I provide opposite each of the open ends of each tube, a stopping
device capable of being operated from the exterior of the wing or water vessel to
which the end of the tube is connected, so that it can be forced against, so as
effectually to close, the end of the tube. Two stopping devices suitable for this
purpose are shown in Fig. 9, one being in its operative position and the other in its
inoperative position. Each comprises a plug or stopper 34 connected to a screw
threaded spindle 35 so as to be rotatable thereon. The screw spindle 35 is screwed
through a plug 36 screwed in the corresponding cleaning hole in the cover plate 27
or 30 opposite the tube plate 26 or 29 of each of the wings 25 and 25 and the
water vessels 2"
2, a washer 37 of suitable material, for instance lead, being
fitted to each side of the plug or stopper 34 so that the latter can be caused to make
a tight joint with the screw plug 36 when in its inoperative position as shown on the
right of Fig. 9, and with the end of the heating tube say 11, when moved into its
operative position as shown on the left of the said figure, at which time a screw
cap 38 is screwed over the outwardly projecting end of the spindle so as to form,
with the aid of a washer 39, a fluid tight joint with the outer side of the screw
plug 36, and thus to prevent leakage of steam between the screw threads of the
spindle 35 and screw plug 36. A stopping device of the kind mentioned may be
used for the purpose specified in water tube boilers of various constructions.
The boiler is mounted on suitable seats 40, which are preferably of sufficient
height to render the underside of the longitudinal water vessels 2ª. 2d readily
accessible and which form ash pits underneath the firegrates. It is also provided
with a suitable casing and with the usual aids to safe and convenient working.
As will be obvious the construction of steam generator herein before described
can be variously modified. For example, instead of a single separator 1, two or
more separators may be used, and the shape of the separator may be modified by
changing the inclination or position and shape of the wings. The number of furnace
chambers may also be less or greater than three, the number of water vessels being
altered to correspond. These vessels instead of being of rectangular form in cross
section, may be of other form, for example circular. The number of rows of

page_text: heating tubes and the number of tubes in each row may also be increased or
diminished according to circumstances. Also in some cases, as for example where
it is desired to reduce the weight of the boiler for given power, the wings 25*
and 25 may be omitted, as shown in Figs. 10 and 11. The upper ends of the
heating tubes are then secured direct to the lower part of the separator 1 (or
separators if more than one be used), which is then provided with a baffle plate 41
and may be furnished with an intermediate water vessel 1 to which it is connected
by vertical tubes 42. The heating tubes may be bent and arranged in the manner
hereinbefore described with reference to Figs. 1 to 4 or in that shown in Figs. 10
and 11, which illustrate an arrangement suitable for a single furnace chamber.
The lower water vessels 2* and 2 are in this case made of crescent-shape in cross
section. They are formed of two parts 43 and 44 of different radii bolted together
by means of flanges 45. To prevent distortion, the part 43 of shorter radius is
provided with diametrically arranged stays 46 and may also be stiffened by means
of ribs or corrugations.
The separator 1 may, if desired, be protected from the direct contact with flame
and hot gases passing through the combustion chamber 20 by circulating tubes 47
connecting the separator 1 to the intermediate water vessel 1° (as shown in Fig. 12);
or by a shield 48 of suitable refractory material such as asbestos (Fig. 12); or by
a combination of these meaus.
As the ratio of the area of the water vessels to the total plan-area of the boiler
is greater in the case of small boilers than in that of large ones,
may sometimes
be necessary to extend the grates 3 into the combustion chamber 20, as shown in
Fig. 10.
49 are walls, made of fireclay tiles or other suitable refractory material, which
serve to protect the lower ends of the heating tubes and the lower water vessels
from direct contact with flame or burning fuel.
When a boiler constructed as hereinbefore described is required to work only at
a low rate of evaporation, the level of the water is arranged to be above the upper
ends of all the beating tubes. As the tubes nearer the rear of the boiler are heated
more than the others, the water is caused to circulate in the boiler up the rear tubes
and down the front tubes. In this case the use of downcast pipes of large diameter
is unnecessary. If however, a high rate of evaporation is required, it will be
necessary to employ downeast pipes of large diameter (such as shown at 33 in
Fig. 1) and to lower the normal water-level, until the upper ends of, say, only one
longitudinal row of tubes on each side is immersed. The fires being urged, the
circulation will be very rapid and large quantities of steam and water will be thrown
against the cover plates 27* (Figs. 2 and 3) or the baffle plate 41 (Figs. 10, 11
and 12), whereby the steam and water will be caused to separate, the water falling
down from the cover plate or the baffle plate respectively upon the tube plate 26
or the lower portion of the separator 1 in which the heating tubes are secured,
which is thereby prevented from being overheated, and the steam passing to the
upper part of the separator.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. A water tube boiler in which the main longitudinal groups of heating tubes
connecting an upper separator with lower water vessels are bent, crossed and
arranged within the boiler sheil or casing in such a manner as to form at the front
end portion of the boiler one or more furnace chambers and, above the same, a
horizontal return flue and at the rear end portion of the boiler an enlarged
combustion chamber connecting the rear ends of the furnace chamber or chambers
with the return flue, and refractory material is applied to crossed portions of the
tubes where they pass over the said furnace cbamber or chambers so as to separate
such chamber or chambers throughout its or their length from the return flue, the
arrangement being such that the lower portions of the said heating tubes will

page_text: traverse the furnace chamber or chambers, whilst their upper portions will traverse
the return flue in a direction at right angles, or approximately so, to the length
'thereof, substantially as herein described for the purpose specified.
2. A water tube boiler comprising an upper longitudinal separator, lower water
vessels, outer groups of heating tubes arranged to form the side walls or shell of the
boiler, two main inner groups of bent heating tubes arranged to cross each other
and form at the front end of the boiler one or more furnace chambers and a
horizontal return flue above, refractory material applied to portions of the tubes
where they cross over the furnace chamber, and an enlarged combustion chamber
the sides and front of which are formed respectively by the said outer and inner
groups of tubes, the arrangement being such that the lower portions of the inner
groups of tubes extend downward through the furnace chamber or chambers whilst
their upper portions extend upward through the return flue in a direction at right
angles, or approximately so, to its length, and that flame and hot gases are caused
to pass rearward from the furnace chamber or chambers into the combustion
chamber and thence in a forward direction through the return flue where they flow
around and between the upper portions of the heating tubes located therein
substantially as described.
3. In a water tube boiler, the combination with an upper separator lower water
vessels, and boiler shell or casing of two main longitudinal groups of tubes
connecting said separator and water vessels and arranged in parallel transverse rows
or sets, the rows or sets in one group being arranged to alternate with and cross
those in the other group and to form therewith one or more furnace chambers and
a return flue, refractory material applied to portions of the said tubes where they
cross over the furnace chamber or chambers, so as to separate the said chamber or
chambers from the said return flue throughout its or their length, and a combustion
chamber at the rear ends of said chamber or chambers and return flue, whether or
not the said parallel rows or sets of tubes be arranged in pairs each consisting of a
row or set from each group and separated from adjacent pairs by a space at least
equal in width to the diameter of one of the said tubes, substantially as herein
described for the purpose specified.
4. A water tube boiler of the kind specified in the preceding claims in which
supplementary tubes connecting the separator with the water vessels are arranged
within the combustion chamber either at the sides and top thereof, or so as to form
walls or partitions serving to divide the large combustion chamber vertically into
two or more smaller ones, the upper portions of the said tubes in either case being
bent and arranged to form a partial roof to the combustion chamber so as to protect
the separator and tube ends from direct impact thereon of flame and hot gases
substantially as herein described.
5. A water tube boiler in which two main longitudinal groups of heating tubes
connect an upper longitudinal separator with three or more lower longitudinal water
vessels and these tubes are so bent, crossed and arranged as to form the sides and
roofs of two or more furnace chambers, substantially as herein described.
6. A water tube boiler comprising an upper separator provided with one or more
wings in communication therewith and having flat opposite sides, lower water
vessels located at opposite sides, of one or more furnace chambers, and each provided
with flat opposite sides, an outer shell or casing, and two main groups of bent
heating tubes connecting the said wing or wings with the lower water vessel and
arranged to cross each other and form at the front end of the boiler, one or more
furnace chambers having close roofs and a return fiue located below said separator
and above said furnace chamber or chambers, and at the rear end of the boiler a
combustion chamber substantially as herein described for the purpose set forth.
7. In a water tube boiler the combination with the heating tubes connecting the
upper separator with lower water vessels, of stopping devices arranged opposite the
open ends of each tube and each comprising a plug or stop provided on opposite
sides with washers of elastic or yielding material, a screw threaded spindle extending
through a screw plug fitted in a hole in the plate opposite the tube plate carrying

page_text: the tube to be stopped so that said spindle can be operated from the ex terior of said
boiler, and a screw cap adapted to be screwed over the outwardly projecting end of
said spindle and to form a fluid tight joint with the outer side of said screw plug
substantially as herein described for the purpose specified.
8. My improved water tube boilers constructed substantially as hereinbefore
described with reference respectively to and shown in Figs. 1, 2 and 3, or modified
according to Fig. 4; and in Figs. 10 and 11 of the drawings annexed, whether or
not a supplementary water vessel 1° be used in the latter construction.
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.