Improvements in the Construction of Externally Fired Tubular Steam Boilers.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in the Construction of Externally Fired Tubular
Steam Boilers.
We, WILLIAM HORNSBY and ROBERT EDWARDS, both of Spittlegate Iron
Works, Grantham in the County of Lincoln, Engineers, 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 :-
This invention relates to improvements in the construction of externally fired
tubular steam boilers.
In carrying out our invention we construct the front part of the boiler with a
shell having tubes in the lower part of it, the shell forming the rear end of the
boiler being extended backwards from the front part and having a fire grate under
it so that the lower part of the shell is exposed to the fire, and the heat of the fire
goes through the tubes in the front part to a smoke box, and thence to the chimney.
In some cases however we return the heat from the smoke box through another row
of tubes placed above the lower lot, and extending from the back end of the rear
shell to the front end of the front shell.
To enable our invention to be fully understood we will describe the same by
reference to the accompanying drawings in which :-
Figure 1 is a sectional side elevation of a boiler constructed according to our
invention, and
Figure 2 is a rear elevation of the same.
Figures 3 and 4 are views similar to Figures 1 and 2 respectively illustrating a
modification of our invention, and
Figures 5 and 6 are similar views illustrating another modification.
In the arrangement shewn in Figures 1 and 2 the hind part A of the shell of the
boiler is of cylindrical shape and the other part B of the shell is also of cylindrical
shape but of larger diameter and attached eccentrically to the part A. Tubes C
pass through the lower part of the shell B into a smoke box or combustion
chamber D, and tubes E pass from the upper part of this smoke box through the
shell A into the smoke box F. The furnace is composed of the walls G, G of fire-
brick or other suitable material and of the walls H, I at the back and front the fire
bars K forming the grate.
The boiler shewn in Figures 2 and 3 is similar in construction to that last
described except that the first smoke box or combustion chamber D is water
jacketted and provided with a door lined with firebrick. This smoke box or
chamber is generally made cylindrical but it can be made of any other shape such
as cylindrical at the bottom, the sides and top being flat and suitably stayed.
In both of the arrangements hereinbefore described a large nud drum L is
arranged under the shell B and the heat from the fire passes through the tubes C,
into the chamber D and from this through the tubes E into the smoke box F
whence it can either be carried into the chimney or return along the side of the
boiler or over the top of the boiler on its way to the chimney.
We sometimes make the shell B oval or with flat sides and suitably stay it from
side to side. Also in some cases we arrange that instead of having a single
shell A, two similar shells are put in its place and attached to the shell B side by
side each shell having its own set of tubes.
In Figures 5 and 6 we shew another arrangement wherein the front part of the
shell B is made cylindrical and has a series of tubes C through its lower part, while
the hind part of the shell A is made smaller than the front part, the lower half
being cut away. The fire grate is placed at this cut away end and the heat from
the fire passes through the tubes into a smoke box F and thence away to the

page_text: chimney. In some cases however we place another row of tubes over the lower
tubes and extending from the tube plate of the smoke box F to the end part of the
shell A. The heat then passes back from the smoke box F through the upper row
of tubes to the chimney; or the heat could be carried round the sides or over the
top of the shell to the chimney.
The boiler illustrated in Figures 5 and 6 is also if desired arranged to be made
with one or more joints in the barrel as shewn at M so that it is in sections for
transport the sections being bolted together when at the destination, and the tubes
put. in and expanded.
By this means a practical boiler can be made of a small diameter no
part weighing over 30 lbs. and no bolts or joint being exposed to the fire. When
a greater power boiler is required than is convenient to make in a single shell two
or more of these shells are placed side by side having a fire grate common to
them all.
By constructing a cylindrical multitubular externally fired boiler as above
described a large grate can be arranged with a minimum of brick work and casings
for the furnace.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. Constructing externally fired tubular steam boilers with the shell of two
different shapes or diameters, the hind part of the shell being smaller than the
front part so that the furnace can be placed under the hind part, tubes being
arranged in the front part of the shell for carrying off the heat from the furnace
into a smoke box at the end, and return tubes being arranged when required
running through the top part of both shells, substantially as described.
2. Constructing an externally fired boiler fitted with heating tubes, with a shell
composed of two cylindrical parts of different diameters joined together and having
suitable end plates, the fire being arranged under the small part of the shell, and
the heat passing through the tubes of the larger part of the shell into a smoke box
or combustion chamber and returning through tubes in the top of the shell into
another smoke box or combustion chamber, substantially as described.
3. Constructing an externally fired boiler fitted with heat tubes, with a shell
composed of two cylindrical parts of different diameters joined together and having
suitable end plates the fire being arranged under the small part of the shell and
the heat passing through the tubes of the larger part of the shell into a water
jacketted smoke box or combustion chamber, and returning through tubes in the
top of the shell into another smoke box, substantially as described.
4. The manufacture of steam boilers' substantially as hereinbefore described and
illustrated in the accompanying drawings.
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11
1043
.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants: