Improvements in Water Tube Steam Boilers.
Year: 1899

page_text: Improvements in Water Tube Steam Boilers.
We, JOSEPH HALLETT, of 108, Fenchurch Street, in the City of London, Con-
sulting Engineer, and GEORGE HALLIDAY, of 23, Alfred Place, Bedford Square,
in the County of London, Engineer, do hereby declare the nature of this inven-
tion to be as follows:-
This invention has reference to water tube boilers of the kind having one or
more steam generating elements or sections (hereinafter called elements) arranged
within a suitable casing and comprising or each comprising two water chambers
or headers (hereinafter called headers) connected to one or more steam and water
drums arranged above them, inclined water tubes connecting the inner walls of
said headers and arranged above a firegrate or grates, and flue tubes connecting
the outer walls of the headers and extending centrally through the water tubes,
or some of them, so as to form therewith annular water spaces, the arrange-
ment being such that flame and hot gases can pass over and amongst the water
tubes and also through the flue tubes, on their way to the chimney.
The present invention has reference to improvements in the construction and
arrangement of such element or elements; to means whereby the hot gases can
at will be caused to flow over and amongst the water tubes and thence direct to
the chimney, or through the flue tubes and thence to the chimney, or partly over
the water tubes to the chimney and partly through the flue tubes to the chimney
and the proportion between the two streams of hot gases regulated to suit varying
requirement; and to certain improved details of construction.
In one construction of water tube boiler according to this invention there are
three steam generating elements each consisting of a front header, a rear header,
inclined water tube suitably secured to the inner walls of the two headers, as by
expanding them in holes therein, and inclined flue tubes that extend through
some of the tubes and are detachably connected as hereinafter described to the
outer walls of the headers. Each element is arranged transversely within a casing
above a firegrate and below a steam and water vessel (hereinafter called a steam
drum) which may be arranged longitudinally of the boiler or transversely and to
which the upper ends of the front and rear headers are respectively connected
by downtake pipes and uptake pipes, the downtake pipes being connected to the
bottom of the steam drum and the uptake pipes to the side thereof, preferably
just above the normal water level therein. Each steam generating element
and the casing are so relatively arranged as to form a rear smoke box and a
front smoke box, each smoke box being provided with a door whereby ready
access can be gained to the adjacent header and tubes. The rear smoke box is
closed at the top by a cover and is in communication at the bottom by a large
rear passage with the rear end of the combustion chamber directly above the
fire grate, and the front smoke box is closed at the bottom and is in communica-
tion at the top with a gas exit passage that leads to a chimney or uptake and is con-
trolled by a damper provided with suitable operating means. The top of the

page_text: space between the headers and above the water tubes is separated from the gas
exit passage and chimney by a cover of refractory material in which is a large
hole or passage controlled by a damper fixed to a rock shaft extending to one or
both ends of the boiler casing and provided with suitable operating means such
as a hand wheel or lever whereby the damper can be opened or closed at will.
The arrangement is such that by fully opening the secondly mentioned damper
and closing the first mentioned damper, the whole of the flame and hot gases
from the fire on the fire grate will be caused to flow over and amongst the
water tubes and through the opening or passage in the cover above the element,
direct to the chimney, and that by closing the second damper and opening the
first one, the whole of the gases will be caused to flow through the rear passage,
rear smoke box, flue tubes and front smoke box to the gas exit passage and thence
to the chimney, whilst by partly opening both dampers, the hot gases will be
caused to divide, part passing amongst the water tubes and through the opening
or passage in the said cover to the chimney direct, and part flowing through the
rear passage to the rear smoke box and through the flue tubes, front smoke box
and gas exit passage to the chimney, the quantity of gases passing by each
route being capable of easy adjustment by regulating the position of the two
dampers.
To facilitate the passage of flame and hot gases to the rear smoke box, the
rear passage is or may advantageously be provided with a hood of refractory
material arranged to extend over the rear portion of the firegrate. This hood
may conveniently be supported in position by the side walls of the combustion
chamber; which, for this purpose, may be formed with side recesses into which
the sides of the hood can be readily pushed from the rear..
The lower water tubes may be without flue tubes and be arranged at a suitable
distance below the water tubes above them so as to form therewith a supple-
mentary combustion chamber or space above the ordinary combustion
chamber located directly above the fire grate. The walls of each header
may be strengthened at points opposite the ends of the supplementary
combustion chamber or space by stays fixed to the inner walls of the
headers and secured to the outer walls thereof by nuts. Baffle plates of refractory
material are or may be placed between the water tubes at different levels so as
to ensure a good distribution of the flame and hot gases amongst such tubes and
to offer sufficient resistance to the hot gases to ensure that some of them will
pass through the rear smoke box to the fire tubes and thence through
the front smoke box to the chimney when the damper is open. The
lower portion of the steam drum and also the downtake tubes and uptake tubes
may be located in the gas exit passage so as to be exposed to the hot gases flowing
through such passage to the chimney, but the said parts might be otherwise
arranged if desired.
To enable access to be gained in a simple and ready manner to the interiors
of the headers of a steam generating element of the kind herein referred to,
for inspecting and cleaning the said headers and for gaining access to the water
tubes therein for the purpose of cleaning, stopping or withdrawing and replacing
such tubes, each header is constructed with a removable outer wall that is
adapted to be secured to a flanged part of the inner plate, which is of dished
shape, by studs or bolts and nuts, the arrangement being such that the outer
wall can be easily removed when desired. In one arrangement the flanged part
is turned outwardly and the outer wall is secured to it by studs and nuts. In
another arrangement the flanged part is turned inward and the outer wall is
secured to it by bolts and nuts.
To enable the flue tubes to be securely fixed in a simple and readily detachable
manner to the outer walls of the two headers of each steam generating element,
each end of each flue tube is provided with a collar and nut that are adapted to
be fixed against opposite sides of a plug which surrounds the tube end and is
sorewed into a hole in the outer wall of the header, the collar being of such size

page_text: as to admit of its being passed through the corresponding water tube. By making
the plugs and holes of sufficiently large diameter, the water tubes can be cleaned,
stopped or withdrawn and replaced, as may be desired, without removing the
outer wall of the header. By fixing the flue tubes in the manner described,
such tubes can be easily detached from the outer wall of one header and be
simultaneously withdrawn from the water tubes by removing the outer wall
of the other header.
When two or more steam generating elements are employed, they may be
arranged side by side over separate fire grates and within separate compartments
of the boiler casing so that each of them may be worked independently of the
other or others. The lower header is or may be provided at its lower end with a
blow off passage leading to a mud drum and when two or more elements are
used, the lower parts of the adjacent lower headers may be connected together
by a pipe secured in flanged holes in the side walls of the headers, the outer side
wall of one of the end headers being connected by a similar flanged part to a
pipe connected to a mud drum or other receptacle, the arrangement being such
that mud collecting in the bottoms of the lower headers can be readily discharged
into the mud drum or other receptacle.
One or some of the herein described improvements may be used without the
remainder.
We, JOSEPH HALLETT, of 108, Fenchurch Street, in the City of London, Con-
sulting Engineer, and GEORGE HALLIDAY, of 23, Alfred Place, Bedford Square,
in the County of London, Engineer, do hereby declare the nature of this inven-
tion 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 improvements in water tube boilers of the
kind described in the Specification of Letters Patent granted to us, No. 5582 of
1899 the object being to improve the construction and working of such boilers
as we shall now describe with reference to the accompanying illustrative draw-
ings wherein Fig. 1 shows partly in front elevation, partly in vertical section on
the line A A of Fig. 2 looking rearward, and partly in vertical section on the
line B B of Fig. 2, also looking rearward, a water tube boiler constructed
according to the present invention. Fig. 2 is a vertical transverse section on the
line CC of Fig. 1. Figs. 3, 4 and 5 are detail views
In the construction of water tube boiler shown, there are three steam generating
elements each consisting of a front header a, a rear header b, inclined water
tubes e suitably secured to the inner walls d of the two headers, and inclined
flue tubes e that extend through some of the tubes and are detachably connected
to the outer walls of the headers, each element being arranged transversely within
a casing above a fire grate h and below a steam and water vessel i (hereinafter
called a steam drum) to which the upper ends of the front and rear headers a
and 6 are respectively connected by downtake pipes k and uptake pipes 1, each
steam generating element and the casing being so relatively arranged as to form

page_text: rear and front smoke boxes m and n respectively of which the former, viz. m
is closed at the top by a cover o and is in communication at the bottom through a
rear passage with the rear end of the combustion chamber q directly above the
fire grate h, and the latter viz. n is closed at the bottom and is in communication
at the top with a gas exit passage s leading to the base of a chimney or uptake
and controlled by a damper j capable of being opened or closed at will. The
top of the space between the headers and above the water tubes is separated
from the gas exit passages and chimney or uptake by a cover u of refractory
material in which is a large hole or passage controlled by a damper w fixed to
a rock shaft, by operating which, as by a lever y, the damper can be opened
or closed at will. Each smoke box is, as usual provided with a door for gaining
access to the flue tubes.
The arrangement is such that by fully opening the damper and closing the
damper, the whole of the flame and hot gases from the fire on the fire grate h
will be caused to flow over and amongst the water tubes c and through the
opening or passage direct to the chimney t, and that by closing the said damper
w and opening the damper j, the whole of the gases will be caused to flow through
the rear passage », rear smoke box m, flue tubes e and front smoke box n to
the gas exit passages and thence to the chimney, whilst by partly opening both
dampers, the hot gases will be caused to divide, part passing amongst the water
tubes and through the opening or passage to the chimney t direct, and part
flowing through the rear passage p to the rear smoke box 'm and through the
flue tubes e, front smoke box n and passages to the chimney.
The above described boiler is similar in construction to that shown and described
in the Specification of our said former patent No. 5582 of 1899, except that the
water and fire tubes cand e are now inclined upwardly and backwardly instead
of downwardly and backwardly as in our earlier construction of boiler, whereby
we obtain a better circulation of the water and the direction of circulation is
always in the same direction in whichever direction the hot gases flow to the
chimney.
Now,
In the previous construction of boiler, owing to the resistance offered to the flow
of the hot gases passing to the chimney through the rear gas passage, rear smoke
box, flue tubes and front smoke box being greater than that offered to the flow of
the gases passing amongst the water tubes direct to the chimney when
both dampers are
a tendency for a
open, there is
much larger pro-
portion of the hot gases to pass by the easier route than by the other to counter-
act which necessitates careful adjustment of the two dampers j and w.
according to the present invention, in order to facilitate the passage of flame
and hot gases to the rear smoke box m and thereby obtain a better and more
even division of the hot gases passing by the said two routes to the chimney,
and thereby enable the large heating surface presented by the flue tubes e to be
fully utilized, the rear passage is made large, as shown, and is provided with
a hood 1 of refractory material arranged to extend over the rear portion of the
fire grate h. By this means the division of the hot gases into two more or
less nearly equal streams of approximately the same temperature can be effected
in a simple and advantageous manner and the evaporative efficiency of the boiler
thereby increased at the time when both dampers are open. The hood 1 may
conveniently be supported in position by the side walls of the combustion
chamber, which, for this purpose, may be formed with lateral recesses into
which the sides of the hood can be readily pushed from the rear.
The lower water tubes c may, as before, be without flue tubes and be arranged
at a suitable distance below the water tubes above them so as to form therewith
a supplementary combustion chamber or space 3 above the ordinary combustion
chamber g, and the walls of each header a and b at points opposite the ends of
the said supplementary combustion chamber or space 3 may be strengthened by
stays 4. 6 are baffle plates of refractory material placed between the water
tubes c at different levels for the purpose of ensuring a good distribution of the

page_text: flame and hot gases amongst such tubes and to offer sufficient resistance to the
hot gases to ensure that a suitable proportion thereof shall pass to the chimney
through the passage p, smoke box m, fire tubes e and smoke box n when the
damper is open. The steam drum i in the example shown, is arranged trans-
versely at the front of the boiler, its lower portion, and also the downtake tubes k
and uptake tubes 1, being located in the passage s so as to be exposed to the hot
gases flowing to the chimney. But this arrangement might be modified.
Each header a and b is constructed with a dished inner plate d and an easily
removable outer wall f, as and for the purpose described in our said former
specification, the outer wall being secured either to an outwardly turned
flange on the inner wall, as by studs 9 and bolts 10 (Fig 1, 2 and 3), or to an
inwardly turned flange 7, as by bolts 11 and nuts 10, (Figs. 4 and 5).
To enable the flue tubes e to be securely fixed in a simple and readily detachable
manner to the outer walls f of the two headers a and b of each steam generating
element, each end of each flue tube is provided with a collar 13 and nut 14
adapted to be fixed against opposite sides of a plug 15 which freely surrounds
the tube end and is screwed into a hole 16 in the outer wall f of the header,
the collar 13 being of such size as to admit of its being passed through the corre-
sponding water tube c. By making the plugs 15 and holes 16 of sufficiently large
diameter, the water tubes c can be cleaned, stopped or withdrawn and replaced,
as may be desired, without removing the outer wall f of the header. By fixing
the flue tubes e in the manner described, such tubes can be easily detached from
the outer wall of either header and be simultaneously withdrawn from the water
tubes by removing the outer wall of the other header.
When two or more steam generating elements are employed, they may be
arranged side by side over separate fire grates and within separate compartments
of the boiler casing so that each of them may be worked independently of the
other or others.
The lower header a is or may be provided at its lower end with a blow off
passage 18 (Fig. 2) leading to a mud drum 19 (Fig. 1), and when two or more
elements are used, the lower parts of the adjacent lower headers may, as in our
previous construction of boiler, be connected together by a pipe 20 (Fig. 1)
secured in flanged holes 21 in the side walls of the headers, the outer side wall
of one of the end headers being connected by a similar flanged part to a pipe 22
connected to the mud drum 19 or other receptacle, the arrangement being such
that mud collecting in the bottoms of the lower headers can be readily dis-
charged into the mud drum or other receptacle.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed we declare that what
we claim is:-
1. In a water tube steam boiler of the kind wherein provision is made for
causing the hot gases to flow either amongst the water tubes direct to the chimney
or through rear and front smoke boxes and flue tubes and thence to the chimney,
or to flow part in one direction and part in the other, providing the passage
leading from the combustion chamber to the bottom of one of the smoke boxes
with a hood arranged to extend over a portion of the fire grate, substantially as
herein described for the purpose specified.
2. The improved water tube steam boiler constructed and operating sub-
tantially as hereinbefore described with reference to the drawings annexed.
Dated this 11th day of June 1900.