AN IMPROVED STEAM GENERATOR
Year: 1878

page_text: LETTERS PATENT to Leighton Mills, of Tynemouth, in the County of Northum-
berland, Mechanical Engineer, and William Clark, of the Town and County of
Newcastle-upon-Tyne, Engineer and Ironfounder, for the Invention of "AN
IMPROVED STEAM GENERATOR."
Sealed the 20th December 1878, and dated the 1st October 1878.
PROVISIONAL SPECIFICATION left by the said Leighton Mills and William
Clark at the Office of the Commissioners of Patents on the 1st October
1878.
LEIGHTON MILLS, of Tynemouth, in the County of Northumberland, Mechanical
Engineer, and WILLIAM CLARK, of the Town and County of Newcastle-upon-Tyne,
Engineer and Ironfounder. AN IMPROVED STEAM GENERATOR."
"
Our Invention consists of two cylindrical chambers one above the other at a
suitable distance apart. Between these chambers are located the ash-pit, the
furnace, and the several furnace flues, all of which assist in generating steam, as is
usually the case in steam generators. The said chambers are not of equal diameter:
the upper one, although of moderate size, is larger than the lower, with which it is
in communication through a system of water tubes arranged in such a manner as
to constitute not only the support of the upper chamber but also serves as the sides
of the ash-pit and of the furnace, and as the division walls of the several flues.
These tubes arranged in sets, two outer and two inner sets, arise from the lower
chamber and join the upper chamber (which contains both water and steam space)
below the water line. The outer tubes throughout their height and length, and
the inner tubes for the greater portion of their length, are placed in close order or
in contact. The inner sets pursuing a serpentine course from below upward, and
meeting above the furnace, form the sides of the ash-pit and of the fire-box, and
they also form a flue beneath the upper cylindrical chamber. The outer sets pro-
ceeding in a circuitous direction from the lower chamber, rise vertically to the
upper chamber, and in their course, by contact with the inner tubes, form several
side flues, through which and through the flue before mentioned the flames and
heated gases from the furnace pass on their way to the uptake or chimney.
го
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page_text: At that end of our improved steam generator furthermost from the furnace door
the inner tubes are (for a short distance only) arranged in open order. They may
here take a serpentine course in a diagonal direction and cross over to the opposite
side. A horizontal partition of fire-brick or other suitable refractory material is
here employed to prevent the flames ascending and to divert them into the side
flues.
Our improved steam generator is fitted with all necessary cocks, feed valves,
steam domes, and the usual furniture. A judicious application of stop-cocks to the
water tubes will permit any pair of water tubes being removed without disturbing
the remainder.
The whole structure may be coated externally with a non-conducting substance,
and when used for sea service encased in sheet iron, or when employed for land
purposes brickwork may be substituted.
The action resulting from the whole arrangement as above described when in
operation will be such as will insure a very perfect and rapid circulation of the
water, a great saving of weight, and an abundance of valuable heating surface.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Leighton Mills and William Clark in the Great Seal Patent Office
on the 31st March 1879.
LEIGHTON MILLS, of Tynemouth, in the County of Northumberland,. Mechanical
Engineer, and WILLIAM CLARK, of the Town and County of Newcastle-upon-Tyne,
Engineer and Ironfounder. "AN IMPROVED STEAM GENERATOR."
Our Invention consists of two chambers, one above the other, at a suitable
distance apart. Between these chambers are located the ash-pit, the furnace, and.
the several furnace flues, all of which assist in generating steam, as is usually the
case in steam generators of the ordinary type.
The upper chamber is in communication with the lower chamber through a
system of water tubes, arranged in such a manner as to constitute not only the
support of the upper chamber but also serve as the sides of the ash-pit and of
the furnace, and as the division walls of the several horizontal flues.
These water tubes arranged in sets, two outer and two inner sets, arise from the
lower chamber and join the upper chamber (which contains both water and steam
space) below the water line. The outer tubes, throughout their height and length,
and the inner tubes, for the greater portion of their length, are placed in close order
or in contact. The inner sets pursuing a serpentine or zigzag course from below
upwards and meeting above the furnace form the sides of the ash-pit and of the
fire-box, and by diverging and proceeding upward to the upper chamber they also
form a horizontal flue beneath the said chamber. The outer sets of water tubes are
employed for a like purpose and in a similar manner; proceeding in a circuitous
direction from the lower chamber they rise vertically to the upper chamber, and in
their course, by contact at certain points with the inner tubes, form several hori-
zontal sides flues through which and through the flue before mentioned the flames
and heated gases from the furnace pass on their way to the uptake or chimney.

page_text: At that end of our improved steam. generator furthermost from the furnace, door
and for a short horizontal distance only the inner tubes are judiciously arranged
and conducted in their upward course in such a manner as to deflect the flames.
from the furnace to the side flues and open a communication from flue to flue. as
will be herein-after more fully explained.
We will now proceed to describe our Invention more in detail by aid of the
accompanying Drawings, in order that the same may be fully understood and
readily carried into effect.
Figure 1 is a cross section (on line A, B, Figure 2) of our improved steam
generator; Figure 2, a longitudinal elevation of the same, partly in section and
with a number of the outer water tubes removed to show more clearly the internal-
arrangement; and Figure 3, a cross section on line C, D, (Figure 2). In these
Figures, L is the lower chamber containing cold or comparatively cold water, and
U the upper chamber, which receives the upward current of heated water and.
steam. F (Figure 1) is the furnace or fire-box formed by the inner sets of water
tubes t¹, t2, arching over the fire-grate f and meeting at c; thence the said water
tubes taking a serpentine course, as shewn in this Figure, and proceeding upward
are attached by any suitable means to and communicate with the upper.chamber U,
thus forming the horizontal flue F. The side flues F¹, F¹, and F3, F3, are formed by
the outer water tubes t³, t, being brought into contact with the inner sets of water
tubes at the bends d, d. Any convenient number of horizontal flues may thus be
formed by curving the inner water tubes to and from the outer sets of vertical
water tubes, care being taken that no portion of the course pursued by the said
tubes above the fire-box is truly horizontal, but that it has such an upward direc-
tion as that the steam may readily escape to the upper chamber.
,
The horizontal flues communicate one with the other by the following means:-
At the end furthermost from the furnace the inner tubes t, 2, (Figures 2 and 3)
take a diagonal direction and cross each other, which consequently produces a space
between each tube, and through which the flames and heated gases escape, as slewn
by the arrows a, a, and b, b, (Figure 3). G is a partition of fire-brick or other
refractory material to confine the flames at this part of their course to the
flues F, F, after which the flames unite in the smoke box at the fore part of the
apparatus and proceed rearwood along the flue F2, thence taking the direction of
the arrows b, b, through the intervening spaces between the inner tubes, as before
explained, return to the front along the flues F3, F³, and are finally emitted from
the chimney or uptake.
H, Figure 2, is a feed valve of any ordinary description and may be fitted if
found desirable to the upper chamber. Assuming our apparatus, as above described,
to be in working order and in operation, the action of the same would be as
follows: The water within the tubes t1, t2, (see Figure 1) round about the furnace
becoming warm would ascend and allow the cooler stratum of water beneath to
rise and take its place. The ascending tendency of this stratum of cold water is
further induced by the weight of the column of comparatively cold water in the
outer tubes t³, t, which is, during the whole operation of generating steam, neces-
sarily conducting in a downward direction a cool stream of water to supply the
place of the ascending hot stream in the inner tubes. Upon the heated particles of
water arriving within the upper chamber they rise to the surface of the water
therein, and each liberate their modicum of steam; having now become cooler and
their specific gravity thus increased, they pass into the current entering the mouths
of the outer vertical tubes, and, carried downward, undergo a repetition of the above
action, see direction of arrows in Figure 1.
By this arrangement we claim a perfect system of circulation and avoid the
clashing or colliding of the ascending and descending particles of water which,
causing a delay in the change of place of each particle, occasion in defective
systems of steam generators the tubes to burn away, always a constant source of
difficulties and dangers in horizontally disposed tubes.
Various modifications of the above-described arrangement, and all embracing the

page_text: same principle, may be employed in actual practice to meet the special requirements
of locality and nature of the work, but for marine purposes we prefer the arrange-
ment shewn in Figures 4, 5, and 6, which are respectively cross section, longitudinal
section, and sectional plan of our improved steam generator adapted for marine
purposes.
In this instance it will be observed that the bottom chamber is divided into two
separate chambers L³, L³, with man-hole doors for fitting and cleansing purposes.
These chambers form as it were feet for the whole of the apparatus to rest upon.
The mode of constructing these chambers are shewn in detail in Figure 8. The
upper chamber may be oval, and the connections between the tubes and the
chamber may be made in a zigzag direction, as shown in Figure 5.
The letters and figures in these views refer to similar parts of the apparatus, as
shewn in Figures 1, 2, and 3, and as these latter have already been fully explained
no further description is necessary except that the mode employed of directing the
flames from the furnace F to the horizontal flue F¹, and from the flue F² to the
flue F³, is somewhat different to the former method above described.
Here some of the inner water tubes, say (2) and their connections, are omitted
from the further end of the chamber L2, and the opposite tubes are brought over, as.
shewn at tx, Figure 4, and made to enter the upper chamber on the reverse side.
By this method, the employment of a fire-brick partition, as shown in Figure 3, is
avoided. The flames will now take the course marked by the arrows, shewn in
Figures 4 and 5, passing from the furnace F to the flue F and conducted to the
smoke box M, Figure 5, from thence into the flue F2 (Figure 4) and onward in the
direction shown by the arrow K into the flue Fs, and finally passing out of the
funnel or chimney at N, Figure 5.
In Figure 7 we have shewn an end elevation of another modification of our arrange-
ment of water tubes, illustrative of one of the many various forms or directions the.
inner tubes may take to fulfil in a measure the object of our Invention, but we
consider the foregoing methods of arrangement superior for the purposes for which
they are intended.
It is of course understood that our improved steam generator is fitted with all
the necessary cocks, feed valves, steam domes, and the usual furniture.
The whole structure may be coated externally with a non-conducting substance,
and, when employed for sea service, encased in sheet iron, or brickwork may be
substituted when employed on land.
Having now described and particularly ascertained the nature and object of our.
said Invention, together with the manner of carrying the same into effect, we would
conclude by observing that what we claim as our Invention and secured to us by
the above in part recited Letters Patent is, an improved steam generator having
tubes so arranged as to form distinct sets or series of tubes for upward and also for
downward currents of steam and water, for the purpose of obtaining circulation and
a ready release of the steam, combined with the principle of arranging the said
tubes so as to form any convenient number of close or practically close horizontal
fire, heat, and smoke chambers, substantially as herein-before more particularly
specified and illustrated upon the accompanying Drawings, or any mere modifications
of the same.
In witness whereof, we, the said Leighton Mills and William Clark, have
hereunto set our hands and seals, this Twenty-eighth day of March, in the
woon of our Loud Ona thousand sight hand