Improvements in Steam Generators.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Steam Generators.
1, JOHN THOM of 93 Hope Street, Glasgow, Consulting Engineer, do hereby
declare the nature of this invention to be as follows:-
This invention has special reference to steam generators of the type generally
called "water-tube" steam generators, that is, generators in which the bulk of
the heating surface is provided by a number of tubes through which the water
circulates, the tubes being secured to a drum, or drums, or vessels, and subjected
externally to the action and heat of the fire gases.
In one form of generator comprising improvements under this invention, there
is employed on either side of the generator, nests of tubes extending between a
point at or near the level of the grate, and an upper horizontal steam and water
vessel or drum, in which said tubes are fastened; and under one construction,
these tubes are of the "Field" type, or Diaphragm type, or return tubes, or a
combination thereof, the lower ends being disposed outside of the grate, and are
carried up in an inclined direction towards each other. These tubes, of whatever
type or form used, in this arrangement, next the grate, and also, preferably, at the
outside, are so constructed and arranged as to form partitions or walls, so as to
conduct the gases of combustion from the back of the steam generator, or end of
the grate, to the front or opposite end, at which part smoke boxes or outlet boxes
or chambers are provided to receive the spent products of combustion, and to
convey or lead them into the uptake or chimney. The beat and gases of
combustion will therefore, in this case, pass .in a longitudinal direction over these
tubes lying between the inner division tubes, and the outer rows of tubes or walls.
In one arrangement or construction, these partition or wall tubes are so made
and arranged as to practically touch each other, and make a practically solid
wall along the sides of the firegrate. To do this, if the tubes are of the "Field,"
Diaphragm, return, or other equivalent type, the necks of the tubes are made
smaller than the body, so as to leave sufficient metal, in the plate of the water
and steam vessel, between the tube ends, in the line of fastening or attachment.
In steam generators having tubes arranged in nests as referred to, and partitions
or walls, the rows or sets of tubes between those rows forming the partitions or
walls, will be smaller than those forming such partitions or walls, and of the same
diameter at the point of fastening with the outer vessel, as in the main body of
them, and spaced apart at suitable distances. Further, in steam generators of the
kind herein referred to, the tubes within the outer and inner rows are arranged
in groups or sets of two rows, that is, two rows or sets of tubes are placed
comparatively close together, and between these sets and the adjacent sets or
groups, a larger space or distance is provided, i.e. a sufficient space through which
a tube could be passed in or out of place, so that it can be easily removed or put
into position; and, in the case of these sets or groups being arranged at right
angles to the direction of length of the nests of tubes, a similar space is, in some
cases, provided between one end of said group, or both ends, and the partition row
or rows.
The tubes may be straight, or they may be bent tubes, having a true radius;
and their lower ends are preferably passed or project through plates, so that they
are not acted upon by the fire gases. The lower ends of "Field," Diaphragm, or

page_text: return tubes, are, in most cases, closed by removable caps, fastened by bolts, studs,
or equivalent means; or they are fitted with screwed plugs or equivalent means.
In some cases, these lower ends are contracted.
In steam generators of the kind herein referred to, that is generators in which
inclined nests of tubes are used on either side of the generator, and are connected
above to a horizontal water and steam vessel, I provide, in some cases, as in a
generator fired at one end only, at the back end, at the space or area not covered
by the end rows of tubes, zigzag, spiral, or like tubular surface, to close or cover
the greater part of this area, both ends of such tubes being fastened or connected
with the water and steam vessel above. By this means, practically the whole end
of the steam generator is formed of or covered with tubes bearing water; and in
some cases to obviate inefficient circulation through such tubes, one of the ends
thereof is carried into the vessel above the level of the other, say nearly up to, or
above the water level.
In steam generators of the kind herein referred to the space within the steam
and water vessel with which the tubes communicate, is sometimes separated into
two by diaphragms, plates or like means, one of which, namely the lower one, is
in communication with the outer tubes of the Field or return tubes, whilst the
other is in communication with the inner tube of the Field tubes, such tubes in
this case being extended up to the diaphragm or plate to which they are fastened,
or by which they are supported; by this feature or arrangement the circulation
within the tubes and generator is controlled, and practically rendered positive.
In some cases, these diaphragms or plates, or some of them, as the case may
be, is or are carried along the lower part of the water vessel, openings being
provided in it or them at certain parts, say at one end, so that the liberation of
the steam takes place at this part of the vessel: in such a case the steam would
be taken off from the vessel at the opposite end, thereby giving it a certain
distance to travel, and stay within the vessel a period of time such as to allow of
the separation from the steam of the water carried by it.
This latter feature may in some cases be applied and used in connection with
other water tube steam generators than those baving Field-tubes, where the
circulation of water passes up and down vertical, or more or less vertical, tubes.
In this case, the plates, diaphragms, or partitions are arranged in the upper steam
and water vessel or vessels, so that one or more rows of tubes is or are adapted
to act as "down" circulation tubes, say, the outer ones, and the others, say, the
inner ones; as "up" circulating tubes; or, the plates, diaphragms, or partitions
are so arranged that some of the tubes, say those at one end, the front ends, are
used as "up" circulating tubes, whilet the others are used as "down" circulating
tubes. In either case, or in any case, if a steam generator adapted to have its
circulation controlled in this manner, it will be seen that some of the tubes must
be separated by the plates, diaphragms, or the like, from the others.
One form of return tube used in a steam generator having inner and outer rows
forming divisions or walls such as described, the upper and lower ends of such
tubes would be contracted and the lower ends coupled together by pipes, the
connections between them being made by means of flanges or bolts, or equivalent
means these connecting pipes would be generally outside the plates above
specified..
In steam generatore in which Field-tubes are employed, and wherein the steam
and water vessel or dome is made of smaller diameter than the length of the inner
tube, the inner tubes are in some cases made of jointed form in the centre, such
as a telescopic construction. By this means, a small diameter steam and water
vessel can be used with tubes of greater length than the diameter thereof, and
yet afford a means by which these inner tubes can be placed in position or removed
from within.
In some cases where two or more generators are placed side by side, the space
between such boilers may be provided with tubes, and the spent gases caused to
pass over or through the tubes, the air used to support combustion of the fuel

page_text: being passed on the opposite side of such tubes, and led into the ashpit of the
generator; by this means a regenerator is provided.
In some cases under this invention, I provide in steam generators of the kind
referred to, duplex and separate grates, and firing doors or arrangements, such
grates being made by placing a row of tubes forming a partition or wall between
the grate bars in either side of the centre. By this means, one of the grates may
be cleaned, whilst the other is in full action, without affecting either.
According to one particular arrangement of steam generator of the kind herein
referred to having Field, Diaphragm, or other suitable tubes, the rows of tubes
next the grate bars, are made in the form of a wall or partition, the tubes touching,
practically; and these partitions or walls are carried from the front to a point
near the back of the boiler; and the end tubes of the nests, and the outer rows of
tubes, are similarly arranged and constructed; while the other tubes between these
rows are of smaller diameter and arranged in groups, and have spaces between
them. In this case, at the front end of the nests, I provide smoke boxes and
uptakes, with suitable doors by which access to the rows of tubes of the nests is
easily had; and where the grate is in duplex arrangement as specified, a central
row constituting a wall or partition is employed. The gases of combustion in this
case pass from the grates to the back end of the generator; thence into the space
in amongst the tubes, and then back between the walls towards and into the
smoke boxes and uptakes. In some cases the steam generator may be fired at
both ends instead of at only one. Also, in some cases, the firing where. desired
can be effected through the sides of the generator instead of at the ends; in which
case, the tubes at the points where the apertures for stoking are situated can be
short, so as to provide the necessary apertures through the rests.
Steam generators with improvements according to this invention will be provided
with bridges, casings, and other fittings, as usual, and as may be convenient or
necessary.
The different constructions, features, and arrangements berein specified, may be
used in different combinations, or separately, and applied to different kinds of
steam generators of the kind herein referred to to which they may be applicable.
Dated this 6th day of February 1896.
CHEESBROUGH & ROYSTON,
15 Water Street, Liverpool, Applicant's Patent Agents.
1, JOHN THOM of 93 Hope Street, Glasgow, Consulting 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 special reference to steam generators of the type generally
called "water-tube" steam generators, that is, generators in which the bulk of
the heating surface is provided by a number of tubes through which the water
circulates, the tubes being secured to a drum, or drums, or vessels, and subjected
externally to the action and heat of the fire gases.
In one form of generator comprising improvements under this invention, there is
employed on either side of the generator, nests of tubes extending between a point
at or near the level of the grate, and an upper horizontal steam and water vessel
or drum, in which said tubes are fastened; and under one construction, these tubes
are of the "Field" type, or Diaphragm type, or return tubes, or a combination
thereof, the lower ends being disposed outside of the grate, and are carried up in

page_text: an inclined direction towards each other. These tubes, of whatever type or form
used, in this arrangement, next the grate, and also, preferably, at the outside, are
so constructed and arranged as to form partitions or walls, so as to conduct the
gases of combustion from the back of the steam generator, or end of the grate, to
the front or opposite end, at which part smoke boxes or outlet boxes or chambers
are provided to receive the spent products of combustion, and to convey or lead
them into the uptake or chimney. The heat and gases of combustion will therefore,
in this case, pass in a longitudinal direction over these tubes lying between the
inner division tubes, and the outer row of tubes or walls.
In one arrangement or construction, these partition or wall tubes are so made
and arranged as to practically touch each other, and make a practically solid wall
along the sides of the fire-grate. To do this, if the tubes are of the "Field,"
Diaphragm, return, or other equivalent type, the necks of the tubes are made
smaller than the body, so as to leave sufficient metal, in the plate of the water
and steam vessel, between the tube ends, in the line of fastening or attachment.
In steam generators having tubes arranged in nests as referred to, and partitions
or walls, the rows or sets of tubes between those rows forming the partitions or
walls, will be smaller than those forming such partitions or walls, and of the same
diameter at the point of fastening with the outer vessel, as in the main body of
them, and spaced apart at suitable distances. Further, in steam generators of the
kind herein referred to, the tubes within the outer and inner rows are arranged in
groups or sets of two rows, that is, two rows or sets of tubes are placed com-
paratively close together, and between these sets and the adjacent sets or groups,
a larger space or distance is provided, i.e. a sufficient space through which a tube
could be passed in or out of place, so that it can be easily removed or put into
position; and, in the case of these sets or groups being arranged at right angles
to the direction of length of the nests of tubes, a similar space is, in some
cases, provided between one end of said group, or both ends, and the partition row
or rows.
The tubes may be straight, or they may be bent tubes, having a true radius;
and their lower ends. are preferably passed or project through plates, so that they
are not acted upon by the fire gases. The lower ends of "Field," Diaphragm, or
return tubes, are, in most cases, elcsed by removable caps, fastened by bolts, studs,
or equivalent means; or they are fitted with screwed plugs or equivalent means.
In some cases, these lower ends are contracted.
In steam generators of the kind herein referred to, that is generators in which
inclined nests of tubes are used on either side of the generator, and are connected
above to a horizontal water and steam vessel, I provide, in some cases, as in a
generator fired at one end only, at the back end, at the space or area not covered
by the end rows of tubes, zig zag, spiral or like tubular surface, to close or cover
the greater part of this area, both ends of such tubes being fastened or connected
with the water and steam vessel above. By this means, practically the whole end
of the steam generator is formed of or covered with tubes bearing water.
One form of a return tube used in a steam generator having inner and outer
rows forming divisions or walls such as described, the upper and lower ends of
such tubes would be contracted and the lower ends coupled together by pipes, the
connections between them being made by means of flanges or bolts, or equivalent
means these connecting pipes would be generally outside the plates above
specified.
In steam generators in which Field-tubes are employed, and wherein the steam
and water vessel or dome is made of smaller diameter than the length of the inner
tube, the inner tubes are in some cases made of jointed form in the centre, such as
a telescopic construction. By this means, a small diameter steam and water vessel
can be used with tubes of greater length than the diameter thereof, and yet
afford a means by which these inner tubes can be placed in position or removed
from within.
In some cases where two or more generators are placed side by side, the space

page_text: between such boilers may be provided with tubes, and the spent gases canted to
pass over or through the tubes, the air need to support combustion of the fuel
being passed on the opposite side of such tubes, and led into the ashpit of the
generator; by this means a regenerator is provided.
In some cases under this invention, I provide in steam generators of the kind
referred to, duplex and separate grates, and firing doors or arrangements, such
grates being made by placing a row of tubes forming a partition or wall between
the grate bars in either side of the centre. By this means, one of the grates may
be cleaned, whilat the other is in full action, without affecting either.
According to one particular arrangement of steam generator of the kind herein
referred to having Field, diaphragm, or other suitable tubes, the rows of tubes
next the grate bars, are made in the form of a wall or partition, the tubes
touching, practically; and these partitions or walls are carried from the front to a
point near the back of the boiler; and the end tubes of the nests, and the outer
rows of tubes, are similarly arranged and constructed; while the other tubes
between these rows are of smaller diameter and arranged in groups, and have
spaces between them. In this case, at the front end of the nests, I provide smoke
boxes and uptakes, with suitable doors by which access to the rows of tubos of che
nests is easily had; and where the grate is in duplex arrangement as specified, a
central row constituing a wall or partition is employed. The gases of combustioni
in this case pass from the grates to the back end of the generator; thence into
the space in amongst the tubes, and then back between the walls towards and into
the smoke boxes and uptakes. In some cases the steam generator may be fired at
both ends instead of at only one. Also, in some cases, the firing where desired can
be effected through the sides of the generator instead of at the ends; in which
case, the tubes at the points where the apertures for stoking are situated can be
short, so as to provide the necessary apertures through the nests.
Steam generators with improvements according to this invention will be provided
with bridges, casings, and other fittings, as usual, and as may be convenient or
necessary.
My invention will now be described with reference to the accompanying drawings
which illustrate by examples, the application of the improvements hereunder, the
novel fentures constituting the improvements under the invention being pointed
out or specified particularly in the claiming clauses concluding the specification.
In the drawings,
Figure 1 is a sectional elevation, Figure 2 a cross section, and Figure 3 a part
plan in section, of a generator according to this invention.
Figure 4 is a cross section, Figure 5 a sectional elevation, and Figure 6 a plan,
of generator shewing further improvements and modifientions under this invention;
and Figure 7 is a sectional plan shewing a steam generator fired at both ends.
Figures 8 and 9 are sectional plan and elevation of details.
Figure 10 is a cross section shewing a steam generator according to this
invention, having a modified construction as regards the upper steam and water
vessel; and
Figure 11 shews a modified arrangement of the tubes.
Referring to the drawings, (and more particularly to Figures 1, 2 and 3) the
generator, it will be seen, comprises a horizontal upper steam and water vessel a,
nests of "Field " tubes & held at their upper ends in the shell of the vessel a, and
extending down in inclined directions; while between them at the lower part, the
grate e is disposed. The tubes forming the nests & are of different forms; namely,
the outer row d and the inner row d' are arranged so that their sides touch
each other, and form water-tube-walls; whilst the tubes e between these walls,
do not touch each other, and are smaller in diameter, but have spaces between
them; and further, at the back end of the grate c, the wall of tubes d' does not
extend to the back of the generator but is stopped, a gap or passage being thereby
formed for the distance w. This gap forms an entrance or communication between
the back of the grate c and the space or chamber between the rows d d'; thus, it

page_text: will be seen, the flames and gases of combustion are first caused to pass from the
front to the back end of the grate, and then through the space o into the chamber
between the tube walls d d', and aloug same to the front end of the generator,
where it is provided on each side with a smoke box,, having a door f in front,
from which gases pass np the aptake g, to tie funnel 9. Within the chamber
formed by the walls of tubes d d, the tubes e are disposed, and over and around.
these the gases pass; but both the tubes e and the wall tubes d d constitute
:heating surface.
According to a further feature hereunder, in some cases there is provided, as
shewn in Figures 2 and 3 (and other figures hereafter described) a duplex furnace
steam generator, the two furnaces being formed by another row or nest of tubes b.
In Figures 1, 2 and 3, these central tubes consist of a single row of tubes touching
each other; or, the central nest of tubes may consist of two or more rows of tubes
as in the outer nests. In the case of duplex furnaces, so formed, being used, one
furnace at one side can be stoked, cleaned, or otherwise attended to, whilst the
-other is in full combustion, and without interfering with it.
The effect and action of this construction is, that the flames and gases of
combustion rising from the burning fuel on the grate or grates c, first, are caused
to pass from the front to the back end of the furnace, heating the inner sides of
the wall tubes d'; and then pass by way of the spaces w into the chambers within
the walls dd', and back to the front end of the generator, heating in the backward
flow the tubes e', and the sides of the wall tubes d d' within these chambers. Thus
the gases have a forward, and then a backward flow, and their heat is gradually
given up to the heating surface of the tubes, entering the smoke boxes f in a
comparatively cool state, and so effecting the highest efficiency and economy.
According to a further constructive feature shewn in Figures 1 2 and 3, the
generator is provided at the back end of the furnace with radiating Field tubes h
arranged as shewa, the necks of which fie closely together at the plate of the
water vessel a, they being fastened within this vessel a, or lying between the end
tube of the wall of tubes d', and the end row of wall tubes d. This arrange-
ment provides heating surface at the end of the furnace, and at the same time
prevents the brickwork; at the end of the generator from falling down in case it
becomes loose.
The lower ends of the outer larger tubes of the Field tubes are provided with
suitable caps d', which are removable for gaining access to them; while their
upper ends are fastened at the necks in the plate of the water vessel a. These
necks in the case of the larger or wall tubes d d', are narrowed where they are
fastened to the drum a, so that they can be fastened in the drum without bending,
and so that their bodies touch each other for the whole length; and the upper
ends of the internal tubes project into the vessel a as shewn.
In some cases, the internal tubes 7 are made in two or more lengths as shewn
in Figure 16, so that they can be placed in position or removed from within the
ressel a, this vessel being of less diameter than the length of the tubes. In the
construction shewn in this figure one part of the tube 7 is provided with an
enlarged part gl or socket into which the end of the lower part slides. The end
of the lower part could fit into the socket with sufficient tightness to make the
two parts hold together to the extent of lifting their own weight; but not so
light as to prevent them being pulled apart by hand or they may be held
together by a pin passed through the two parts. Thus when the upper half tube
is drawn into the vessel a, it can be taken off the lower part, and then the lower
part can be taken out of the outer tube. Another form of inner tube q consists
in making one half smaller than the other and arranging one part to telescope into
the other.
The nests of tubes are enclosed externally at the top and bottom by a simple
metal plate; and this plating in some cases (as shewn on the left hand side of
Figure 2) is carried down below the ends of the tubes at A, and provided at the
front end with sliding doors; thus this lower portion forms a box or receptacle

page_text: for ashes or dirt which may fall, and which can be withdrawn therefrom through
suitable doorways. In another case (as shewn on the right hand side of Figure 2)..
the nests of tubes are enclosed below by a plate through which the ends of the
intermediate tubes e pass, this plate being held in place by catches hinged to
the caps of the outer tubes d. The plate is made to fit about the tubes, and
completely closing the bottom of the nests. This construction of generator
requires at its sides no brick work, and the only brickwork wall (5) is that at the
back end of the furnace, and this is held in position or prevented from falling by
the end tubes h.
The tubes shewn in Figures 4 to 6, are return tubes consisting of a small one-
and a large one, as in the Field tube, but in this case the one being outside the
cther and connected at the lower end and carried up in return form. This.
construction of tube comprises the combined characteristics of Field and ordinary
tubes. In this case the smaller tubes (q) serve as the up current tubes, and the
larger ones as down-current tubes. These tubes are fastened at the upper ends to-
the shell a as shewn; while their lower ends are fitted in boxes k, with covers ³,.
fastened by bolts, at their lower ends for gaining access to them, and to the
tubes. The larger tubes forming the tube walls, have their necks of smaller
diameter than their bodies, so that they can be fastened in the shell a without
bending, and their bodies touch along their whole length. Instead of providing
these return tubes in pairs, as described, each pair having a box k, they may.
be arranged in sets of two or more of the small and larger tubes, with common
boxes k.
In these Figures 4 to 6 and 8 and 9, in which this construction of return tube
is shewn, there is also shewn a modified arrangement of steam generator provided
with this form of tube; namely, the nests of tubes 6 consist of three sets of return,
tubes consisting of the larger and small tubes. The larger tubes touch each
other, and are shruuk where they fit in the vessel a, and the boxes ; and these.
tubes are so arranged in rows, as shewn, that the gases from the furnace pass from
the back end of same, into the space between the inner and intermediate row of
tubes d' and dx, to the front of the generator; and then return back through the
space between the intermediate row dx and the outer row d, to the back end of
the generator, where it would be provided with smoke hoxes which lead the gases
to the chimney, the gases of combustion passing over both the larger and smaller
tubes. Thus a lengthened run of the gases and time contact with the heating
surfaces in passing from the furnace to the chimney is obtained, with the result.
that as much heat as is practically possible is utilized and transferred to the
water.
The sectional plan in Figure 7 shews a generator fired at both ends, in which-
the side nests of tubes are arranged as in Figures 4 to 6. The gases of com-
bustion in this case first pass to the back of the furnaces, niz. at the centre of the
generator, and enter the nests b through the spaces to in the inner tube walls..
From here they pass to the two front ends and then back to the central part at
the outside of the nests, whence they pass into the smoke boxes f, as shewn by the
arrows. Doors f1 are provided at the front ends of the generators to permit of
the tubes being brushed from these ends and access obtained to them. Inter-
mediate tubes between the tube walls d d d are provided in the construction
shewn in this figure.
This arrangeinent of tube walls by which the return flow of the gases through
nests of tubes in water-tube steam generators is effected, may be employed, in some
cases, without the intermediate smaller tubes e, and in different kinds of the modern.
type of water-tube steam generators.
Figures 10 and 11 shew modifications wherein the part of the shell a in which
the tube ends are fastened is flattened completely or partially as shewn, respectively,.
on the left, and the right hand side, these flattened parts being stayed by internal
girders, with stay bolts extending between the shell and such girders. The
plau in Figure 11 of this arrangement shews the position of girders and bolts...

page_text: In this case, the door by which ashes and dirt are removed from the casing of
the generator, is binged to the side plate of the ashpit, and opening from the front
end about said hinge. The tubes in this case are shewn supported at their lower
ends and kept in position by the longitudinal guide bars n, which are introduced
between the rows of tubes, and are kept in position by the caps d being made a
little larger in diameter than the tubes.
According to a further feature under this invention, the internal smaller tubes e
of the nests are arranged in sets, and spaces are privide between these sets so
that ways or passages are provided by which any tube can be passed along these
ways when a tube is to be taken out, or put in position from any point, from the
front end of the generator, or smoke-box doors. For instance, in Figures 1, 2
and 3, there are lateral spaces or ways between the internal tubes e, whilst
longitudinally, there is another way or space y at one side between said internal
tubes and the inner wall tubes d', and through these ways any of the small tubes e
can be passed in or out when putting it in place or taking it out. In the arrange-
ment shewn in Figures 10 and 11, the same effect is obtained, but this is secured
by making this way zigzag, as indicated by the line y', which is drawn through
the centre of this way.
With regard to the details of steam generators, (riz., those of the kind
shewn in Figures 1, 2, and 3), details of construction of caps or means for
closing the lower ends of same, are shewn in Figures 12 to 15; and there is
also illustrated in Figure 13 an automatic means for closing the tubes when the
circulation in them ceases from any cause, as for instance in case of a burst. In
these Figures 12 and 14 are sectional elevations, and Figures 13 and 15 plans of
same, respectively.
Referring now to the closing caps or covers d for closing the lower ends of the
large Field tubes, or wall tubes d'or d', they are held in position by a T bult d³,
the ends of the horizontal bar of which rest on an internal flange de in the tube
end, while the shank is threaded and has a nut d' thereon; and by screwing it up,
the caps are pressed tightly and make a watertight joint with the flanges d.
The upper part of the horizontal bars of the T bolts are carried up to form a
projection d³, over which the lower end of the inner tube fits as shewn; said inner
tube being provided with holes of sufficient area to allow of the ontlet of water
from the inner to the outer tube. The T bolts do in this case can be introduced
into the tube from the lower end.
The construction of cap, and mode of holding it in position, shewn in Figures 14
and 15, is the same as that just described and shewn in Figures 12 and 13, with
the exception that the holding part a, instead of being a har, consists of a disc,
and together with its shank, the whole device takes a mushroom form. In this
case, (which is more particularly applicable to the smaller kind of tubes e) these
bolts are introduced from the upper end of the tube, and are used more especially
in connection with the smaller tubes used in the generator.
The automatic means of closing a tube in the case of the circulation ceasing, as
when a burst takes place, shewn in Figure 14, consists of an automatic lift valvular
device, so arranged, that the upward flow of water from the outer tube of an
annular tube, acts upon, lifts, and normally keeps open, a valve while the circulation
lasts; but when the circulation stops, through a burst, or when the cap at the
lower end of the tube is removed, this valve falls and closes the mouths of the
inner and the outer tubes. In the construction shewn, the valvular device consists
of a seat portion o fitting into the mouth of the outer tube of such annular pair
of tubes, and an internal annular tubular portion o, formed one with o by webs
therefrom, and supporting the internal tube from its lower end, as shewn. The
upper edges of o and o' form seats on which the valve o rests when the valve is
closed. This valve o has a flange o³ and a cap or roof of, and slides up and down
on the shank of the tube o. At the upper end of the valve under the cover of
apertures are provided, which form inlets to the inner tube. The movement of
the valve o' on the inner tubular part o' is controlled by pins of working in slots o'.

page_text: In action, the upward flow of water in the outlet tube lifts the valve o' into the
position shewn in the drawings, thereby providing an outlet between the flange o
and the seat o, and at the same time, moving the cover of off the lip of the
part o¹, and freely opens the inlet passages o to the interior of o', circulation
taking place in the direction indicated by the arrows. When the circulation ceases
from any cause, the valve o' falls down, the cover of closing the mouth of ol and
the flange o' closing the seat o, and therefore no water can pass out.
In the drawings bereto annexed, the generators shewn have only a single upper
water and steam drum (a) with return tubes, there being no side water drums
connecting the lower ends of the tube as usual; it is however to be understood
that such of the improvements herein described, as are applicable to this latter
kind of steam generator may be used in connection with such generators without
departing from this invention. Also the generators may be arranged back to back
or end to end, and fired at the ends (or sides if desired), and in some cases where
they are arrauged in sets of two or more side by side, the space between them may
be utilized as a space in which the air supplied to the furnaces may be heated by
the waste gases of combustion, in suitable air heating pipes or apparatus.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed, declare that what I
claim is :-
1. The herein described improvement in water-tube steam generators having an
upper water vessel, and nests of tubes descending down from same over a furnace
below, cousisting of the construction wherein the gases of combustion are caused
to pass to the back of the furnace, then into the nests of tubes, and then back over
the tubes in such nests to the front in the opposite direction, or to the front and
then again to the back: for the purposes specified.
2. The herein described improvement in water-tube steam generators having an
upper water vessel, and nests of tubes descending down from same over a furnace
below, consisting of the construction wherein such nests of tubes are arranged with
inner and outer walls composed of tubes touching each other, and so disposed that
the gases of the furnace pass to the back end of the generator, enter the spaces
between said walls of tubes, and then flow in return or opposite direction or
directions; substantially as and for the purposes set forth.
3. In a steam generator having an upper water vessel, and nests of tubes
descending from same over a furnace below, the employment in said nests of tubes,
of return tubes for the circulation of water, fastened in their upper necks to the
said upper water and steam vessel, and provided with rows of tubes d d' at the
sides of said nests and constituting tube-walls, and tubes e within the chamber
formed by said wall tubes, the fire gases being caused thereby to pass to the back
of the generator, and then to the front into smoke boxes; substantially as and for
the purposes set forth.
4. In steam generators having characteristics as referred to in the preceding
claims, the construction herein described consisting of outer nests of tubes, and one
or more intermediate rows or nests of tubes extending longitudinally along the
generator, and separate grates or furnaces arranged between said nests or rows of
tubes; substantially as set forth.
5. In steam generators of the kind herein referred to, having a water vessel and
tubes extending down from same, the arrangement of such tubes in nests, and
providing therein a way or ways such as x, or x and y, by which the tubes can
be passed from or into any part of the nests; substantially as and for the purposes
set forth.
6. In a steam generator having an upper water vessel, and nests of tubes
extending down from same on either side substantially as described, the employ-
ment and arrangement of the tubes & arranged in connection with brickwork at
the back of the furnace (i.e. in front of same) by which such brickwork is prevented
from moving or falling out of place; substantially as set forth.

page_text: 7. In a water tube steam generator, the employment in combination with an
upper water vessel, of return tubes of the form or construction described,
having the necks of the larger and smaller tubes fastened in the water vessel,
the lower ends of same being connected: substantially as and for the purposes set
forth.
8. The return tube, having its two tubes of different sizes connected together in
pairs at their lower ends, as set forth with reference to Figures 4 to 6 and 8 and 9
of the drawings.
9. In a water tube steam generator having return tubes of the type charac-
terized in the preceding Claims 7 and 8, the arrangement of such tubes so that
the large tubes touch each other forming tube-walls, and having spaces between
such walls for the flow of gases over them; substantially as set forth and shewn.
10. In water tube steam generators having "Field-tubes," the construction of
the lower end of said tubes with caps or covers constructed and adapted to act
substantially as set forth with reference to, and shewn in Figures 12 to 15.
11. In a water tube steam generator having "Field tubes," the construction of
the inner tubes thereof in two or more parts; substantially as and for the purposes
.set forth.
12. In a water tube steam generator having a water vessel a and Field or
return tubes fastened therein, the employment of walls of such tubes, the necks
of which are of smaller diameter than their bodies and fastened and arranged as
and for the purposes set forth.
13. The steam generator consisting of the water vessel a, nests of tubes b,
furnace or fornaces c, and uptakes or smoke boxes f, as set forth with reference to
and shewn in Figures 1 to 3 of the drawings.
14. The generator consisting of the water vessel a, nests of tubes b, and grate c,
arranged, constructed and operating, as set forth with reference to Figures 4 to 6,
of the drawings, respectively.
15. A steam generator of the water tube type, having its tubes arranged and
operating as set forth with reference to Figure 7 of the drawings.
Dated this 6th day of November 1896.
CHEESBROUGH & ROYSTON,
15 Water Street, Liverpool, Agents.