IMPROVEMENTS IN THE CONSTRUCTION OF TUBULAR BOILERS, OR STEAM GENERATORS, AND SURFACE CONDENSERS, AND SUCH LIKE APPARATUS, AND IN THE METHOD OF FORMING, APPLYING, FITTING, AND USING METAL TUBES FOR THE SAME
Year: 1860

page_text: PROVISIONAL SPECIFICATION left by Thomas William Miller; at the
Office of the Commissioners of Patents, with his Petition, on. the 14th
July 1860.
I, THOMAS WILLIAM MILLER, of Her Majesty's Dockyard, Portsmouth,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
THE CONSTRUCTION OF TUBULAR BOILERS, OR STEAM GENERATORS, AND SURFACE
CONDENSERS, AND SUCH LIKE APPARATUS, AND IN THE METHOD OF FORMING, APPLYING,
FITTING, AND USING METAL TUBES FOR THE SAME," to be as follows:-
This Invention relates to improvements in the construction of boilers or
steam generators, by forming and employing metal tubes spirally twisted or
twisted around the longitudinal axis, by which a variation in the section of
such tubes may be effected, according to the form and number of the threads
imparted to the metal tube, as may be desired or found useful, and such
tubes are substituted for the ordinary cylindrical tubes of circular bore,
which have heretofore been employed in the construction of tubular
boilers, surface condensers, and for other similar purposes, and I substitute
tubes of the form and character described, whether the water or steam be in
contact internally or externally, and the flame or heated products of com-
bustion act or impinge upon the external surfaces, or pass through the interior
of such spiral tubes, the object being to cause the water and steam to circulate
more thoroughly and rapidly, and that the flame and heated products of com-
bustion may be caused to impinge more perfectly upon and remain for a
longer period in contact with a greater number of heat-abstracting surfaces,

page_text: and by continually changing the surfaces of the heated products in contact
with the metal, obtain better results therefrom.
It also, and in like manner, relates to the construction of surface condensers,
in which, within a given space, and with a given power for the pumping
of condensing water, a rapid and perfect circulation of the cold-condensing
water on the one side of the tubes, and of the steam to be condensed on the
other sides of the tubes are the objects attained.
It likewise relates to the construction of refrigerators or coolers in general,
as well as to vaporisers, and other such or similar apparatus.
It consists in inserting into steam boilers or steam generators, and surface
condensers, refrigerators, vaporisers, and such like vessels or apparatus, or
wherever heat as to be imparted to or abstracted from fluids or their vapours,
or air or gas tubes of one or other of the forms or sections hereafter described,
by which the fluid, vapour, air or gas, is caused to rotate, tumble over, and
constantly change its direction of motion whilst passing through the interior
of such tubes, and thus set up a more perfect circulation, or when flame, or
the products of combustion, as in the case of a steam boiler or steam gene-
rator, or when the condensing water or fluid, or air employed for cooling or
refrigerating, is caused to pass around, over, or through amongst the tubes
so formed and fitted, or through the interior of such tubes as in the case of a
surface condenser, the heat has more time, and better opportunity for acting
upon the one surface, whilst the fluid or other body to be heated is caused to
more perfectly circulate and present the whole of its parts to the action of
the heat; in like manner the operation of condensing steam, cooling, or refri-
gerating, which being similar in principle to, but the reverse of that which
takes place in imparting heat, I employ for the same purpose metal tubes
spirally formed, or twisted screw-like, or having their surrounding surfaces
corrugated spirally in the direction of the length.
Instead of employing one tube so formed, or a series of single tubes of the
kind and description herein-before described, and mounting a series of such
tubes between two tube plates or their equivalents, and causing the current
of the body passing through to do so in the shape of a solid column, I prefer
for some purposes to place one spiral tube inside of another, of a suitably
large diameter to allow of a spaco around the exterior surface of the inner
tube being left to form a passage. In this case the tube plates for the inner
and smaller tubes would be of a greater distance apart than the exterior or
tubes of a larger diameter.
The ends of the tubes may either be left circular as usual for the purpose
of enabling them to be inserted into the ordinary description of holes usually

page_text: formed in tube plates, or the tubes may be uniformly twisted, screwed, or
spirally formed from end to end; and the holes for receiving the ends of such
tubes may be formed in the tube plates by means of cutters of the same form
and pitch as the tubes, and ferules of corresponding shape may be inserted,
or the tubes may be secured in the tube plates without ferules by using conical
drifts for expanding the ends of the tubes into the holes which have been
prepared to receive them.
The desired form or character may be given to the tubes by pressure in
dies, or by drawing and pressure combined between "part dies" or stocks
containing the expanding pieces by which the form is given, or any other well-
known means may be employed for producing tubes of the requisite form or
shape, capable of withstanding great pressure applied either internally or
externally.