Improvements in Internal Flue Steam Generators.
Year: 1890

page_text: Date of Application, 4th Mar., 1890-Accepted, 26th Apr., 1890
COMPLETE SPECIFICATION.
Improvements in Internal Flue Steam Generators.
I WILLIAM MALAM of Edgemoor in the County of Newcastle State of Delaware
United States of America Boiler Maker 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:-
The object of my Invention is to materially improve the steam producing qualities
of that class of steain generators which have internal flues for the passage of the
products of combustion and this object I attain mainly by combining the flue
structure of such a generator with a fire-box having in the upper portion tubed
transverse water legs of a character similar to those shewn in my patent No. 10020
dated August 24th 1885 tubes being also employed instead of solid stays for the fire-
box walls, in some cases, so as to still further increase the heating surface.
In the accompanying drawings
Figure 1 is a longitudinal section of a boiler of the type known as the "Galloway"
boiler, with fire box constructed in accordance with my Invention.
Figure 2 is a transverse section on the line 1-2, Figure 1.
Figure 3 is a transverse section on the line 3-4, Figure 1.
Figures 4, 5, 6, 7 and 8 are longitudinal sections of other forms of internal flue
boilers, constructed in accordance with my Invention, and
Figures 9, 10, 11 12 and 13 are transverse sections on the lines 5-6 of
Figures 4, 5, 6, 7 and 8 respectively.
In the boiler shewn in Figure 1, A is the outer casing or shell, and B the internal
flue which is of the segmental forin shewn in Figure 3, and is crossed from bottom
to top by a series of sets of circulating pipes or tubes a, three of these in each
set being shewn in the drawing, as in one of the forms of the well known
Galloway" boiler, some of the tubes being inclined and all of them being flared
from bottom to top, so as to facilitate the circulation.
"6
Boilers of this class however have heretofore had their fire-places or furnaces
directly in the front ends of the flues or in forward continuations of the same, hence
where the products of combustion are hottest but a small area of heating surface is
exposed to the water in the boiler, and this area is not such as to cause the rapid
circulation of the water in contact therewith.
In order to overcome this objection, I combine the flue with a deep fire box D,
having water chambered walls b similar to those of the locomotive type of boiler, and
the crown sheet of this fire box I provide with depending water legs F, having
tubes extending transversely through the same, as shown in Figure 1 and as set
forth in my Patent before alluded to.
By this means an extended heating surface is provided at the point where the pro-
ducts of combustion are hottest and the steam producing qualities of the boiler are
consequently much improved.
I also prefer in some cases to carry short tubes 9 through the water jacketed legs
of the fire box these tubes communicating with chambers on the outside of the
casing as shown in Figures 1, 2 and 3.
The products of combustion enter or pass through these tubes which thus add to
the heating surface of the boiler and serve as substitutes for the solid stays ordinarily
employed for the walls of the fire box.
In Figures 4 and 91 have shown the application of my Invention to a boiler having
an internal flue B with vertical circulating tubes a extending through it and in
Figures 5 and 10 I have shown a boiler of substantially similar character with the
exception that the circulating tubes are tapered as in the boiler shown in Figure 1
the axes of all the tubes however being vertical instead of the outer tubes being
inclined.

page_text: In Figures 6 and 11 I have shewn a boiler having two cylindrical flues instead of
the laterally elongated flue shewn in the previous figures, this flue being crossed by
circulating tubes, some of which are inclined from right to left, and the others from
left to right.
In Figures 7 and 12 the same arrangement of circulating tubes is illustrated in
connection with a boiler having a single internal cylindrical flue, and in Figures 8
and 13 my improved fire box is shown in connection with a boiler having an internal
cylindrical flue without circulating tubes.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed I declare what I claim is.
First. The combination in a steam boiler, of the outer casing or shell, an internal
longitudinal flue for the passage of the products of combustion, and a fire box having
water jacketed walls, and tubed transverse water legs in its upper portion, substantially
as specified.
Second. The combination in a steam boiler, of the outer shell or casing, an internal
longitudinal flue with circulating tubes crossing the same from top to bottom, a fire
box communicating with said flue and having water jacketed walls, and tubed
transverse water legs in the upper portion of said fire box substantially as specified.
Third. The combination of the water jacketed walls of the fire box, having external
chambers thereon, with tubular stays communicating with the fire box and with said
external chambers, substantially as specified.