IMPROVEMENTS IN STEAM BOILERS
Year: 1878

page_text: LETTERS PATENT to John Smith, of No. 17, Queen Victoria Street, in the
City of London, Engineer, for the Invention of "IMPROVEMENTS IN STEAM
BOILERS."
Scaled the 24th September 1878, and dated the 22nd June 1878.
PROVISIONAL SPECIFICATION left by the said John Smith at the Office of
the Commissioners of Patents on the 22nd June 1878.
JOHN SMITH, of No. 17, Queen Victoria Street, in the City of London, Engineer.
"IMPROVEMENTS IN STEAM BOILERS."
This Invention relates to improvements in steam boilers.
According to my Invention instead of employing only one fire-box from which
the heated products of combustion ascend directly to the flue I construct above it
one or more combustion chambers, connected by one, two, or more large tubes for the
passage of the heated products of combustion.
For very large boilers, where there are more than one (generally two) boxes for
firing, the two lead by connections into a combustion chamber at the back, having
a larger tube for communication with the upper combustion chamber or chambers.
This addition of one or more combustion chambers gives a greater extended heated
surface. The upper of the said combustion chambers is baffled at the outlet to the
flue, as is also when desired the fire-box.
The fire-box or boxes, and also the combustion chamber or chambers, are well
filled with hanging circulating tubes, the construction of which form a feature of
my Invention. They are double; the outer tube of each is fixed to the top plate of
the box or chamber and is closed at its lower end, which is usually of hemispherical
form. At the upper end of this tube a perforated bulb is inserted (not fixed), from
the upper part of which a tube dips into the said outer tube nearly to the bottom
thereof, and is open at both ends; the outer tube being exposed to the heat of the

page_text: box or chamber in which it hangs, the water in the annular space between the two
tubes becomes quickly more heated than the water within the inner tube, and con-
sequently rises and passes out of the perforations in the said bulb, and is imme-
diately replaced by water descending the inner tube; a constant circulation of
water is thus maintained through both the inner and outer tubes, thus preventing
to a very great extent any incrustation thereof, and what does form will be on the
cooler and inner tube, which not being fixed may be readily removed and cleaned.
The circulation through the tubes is so rapid that the issue of the rising water
from the perforated bulbs if properly directed downwards by the direction of the
perforations, will scour the tube plate and effectually prevent incrustation on a part
usually first to suffer, and where it proves so injurious. Those tubes may be used
in other forms of boilers than those described herein.
The stays of the boiler form another feature of my Invention, they allow of all
expansion and contraction of the boiler without straining the boiler or causing any
damage. I will describe the stays between the top plate of the upper combustion
chamber and the crown of the boiler. The lower end of each stay passes through a
hole in the plate of the combustion chamber, and is retained in position by two screw
nuts, one on each side of the plate. The outer end, or that attached to the crown
of the boiler, does not pass through the crown but through a helical or volute spring;
the length and set of the stay being determined by a screw nut on the end thereof,
against which one end of the spring bears. The other end bears against the inner
side of a cup case or double bracket, which is bolted or rivetted to the inside of the
crown, so as to compress the spring, and thus brace together the two plates between
which the stay is fixed. Any further sitting is effected from the other end of the
stay by means of the said screw nuts. These stays may be employed for boilers
now in use.

page_text: In the accompanying Drawings,-
Figure 1 is a sectional elevation of one form of boiler constructed according to
my improvements.
Figure 2 is a sectional elevation of a modified form of boiler constructed
according to my improvements, taken on the line a, b, Figure 4; Figure 3, a
sectional plan taken at the line c, d, Figure 2; Figure 4, a sectional plan taken at
the line e, f, Figure 2.
Figure 5, a sectional elevation of a vertical boiler of ordinary construction with
some of my improvements attached; and Figure 6, a sectional plan taken at g, h,
Figure 5.
Figures 7 and 8 shew some of my improvements applied to other forms of
boilers.
And Figures 9 to 13 are detail on an enlarged scale.
According to one part of my Invention (which relates to improvements in steam
boilers) instead of employing only the fire-box as the heating chamber, and from
which the heated products of combustion ascend directly to the flue, I construct
above the ordinary fire-box (A, Figure 1) a combustion chamber B, connected with
the fire-box A by one, two, or more large tubes C. In the Drawing two are shewn.
There may be more than one combustion chamber B, placed one above the other,
or mado smaller and placed side by side. The heated products of combustion pass
from the fire-box through the tubes C into combustion chamber B, and thence to
the flue, the entrance to which may be baffled, as shewn in the Drawing, or left
open, as desired.
For large boilers having more than one (generally two) fire-boxes I construct the
boiler (Figures 2, 3, and 4) with two conbustion chambers D, D, behind fire boxes
E, E, communication between each pair of fire box and combustion chamber being
by large tube F. These combustion chambers D, D, again communicate by tubes
G, G, with a large upper combustion chamber (or chambers) H of similar con-
struction to that already described. Instead of the two combustion chamber D, D,.
one larger one may be employed. The introduction of these combustion chambers
gives a greatly increased heating surface.
ر
The fire-boxes and the combustion chambers are all well filled with hanging.
circulating tubes I, the construction of which tubes forms a feature of my Invention,
and is shewn at Figures 9, 10, and 11, Figure 9 being a vertical section; Figure 10,
a plan; and Figure 11, a section at i, j, Figure 9. These tubes I, as will be seen,
are formed double, i.e., of an inner and an outer tube. The outer tube I is attached
in the ordinary way to the top plate of the fire-box or the combustion chamber,.
and is closed at its lower end, which by preference is of hemispherical form. At
the upper end of this tube a perforated bulb 12 is inserted (not fixed), from the
upper part of which the inner tube I' dips. This tube is open at both ends, and
does not reach quite to the bottom of outer tube. I. The under side of bulb I² is
also perforated with holes 13 of any desired shape, and formed with a downward
direction. The outer tube I being exposed to the heat of the fire-box or the com-
bustion chamber in which it hangs, the water in the annular space between the
inner and outer tubes becomes quickly heated, and consequently rises and passes
out through the perforations in the bulb, its place being at the same time taken by
the cooler water descending the inner tube. A continuous circulation of water
down the inner tube, up the outer tube, and out of the perforations in the bulb,
is thus produced and maintained, providing a means of rapidly heating the water,

page_text: and at the same time preventing almost entirely the formation of incrustation in
the tubes, whilst the little that forms, if any, is on the inner and cooler tube, which
not being fixed may be readily removed and cleaned.
Moreover when the circulation through the tubes is fairly started it is so rapid
that the water issues from the bulb with such force as to effectually scour the top
plate of the fire-box or combustion chamber and prevent the formation of in-
crustation thereon, a point of great importance, as this is a part generally first
attacked, and is of vital importance to keep clean and sound. These tubes may be
used in almost any form of boiler. Figures 7 and 8 shew them applied to ordinary
egg-ended and Cornish boilers.
The stays of the boiler forin another feature of my Invention, they allow of all
necessary expansion and contraction of the boilor without straining any part of it.
These stays J are shewn in Figures 1 and 2 between the top plate of the combustion
chamber and the crown of the boiler, and in Figure 5 between the top plate of the
fire-box and the crown of the boiler. The lower end of each stay passes through
a hole in the top plate of the combustion chamber (the top one, if more than one
are employed, one above the other), or the fire-box if no combustion chamber is used,
and is retained in position by two screw nuts, one on each side of the plate. The
end attached to the crown plate of the boiler may be fixed in two ways, the way
I profer I will describe first. It does not pass through the plate but through a
helical or volute spring K. (see Figure 12), the length of the stay being adjustable
by a screw nut L on the end thereof, against which the spring bears. The inner
end of the spring bears against the inner side of a cup case or double bracket M,
which is bolted or riveted to the inside of the crown plate of the boiler, so as to
compress the spring, and thus brace together the two plates between which the stay
is fixed. Any further setting is effected from the other end of the stay by means
of the said screw nuts. The other way of fixing the spring-controlled end of the
stay is for it to pass through the crown plato of the boiler through a stuffing box,
thus having the spring outside of the boiler. Figure 13 shews another way of
securing the inner end of the stay. These stays may be used in boilers of ordinary
construction.
My improvements are equally applicable to marine as to land boilers.
I claim as my Invention,-
First. Constructing steam boilers with a combustion chamber or with combustion
chambers in addition to the fire-box or fire-boxes, substantially as described and
illustrated.
Second. The construction of the circulating tubes, substantially as described and
illustrated.
Third. The construction and mode. of fixing the stays, substantially as described
Witness,
JOHN W. GRAY, C.E.,
Consulting Engineer & Patent Agent,
16, Southampton Buildings, W.C.
JOHN SMITH. (L.S.)