Improvements in High Pressure Steam Generators.
Year: 1896

page_text: Date of Application, 7th Apr., 1896-Accepted, 9th May, 1896
COMPLETE SPECIFICATION.
Improvements in High Pressure Steam Generators.
I JOSHUA ENTWISLE, Manager with the Firm of E. K. Dutton & Co.,
Chartered Patent Agents, of 5 John Dalton Street, Manchester, in the County of
Lancaster, do hereby declare the nature of this invention (communicated to me
from abroad by Edward T. Sederholm, of 1629 Fulton Street, Chicago, Cook
County, Illinois, United States of America, Mechanical Engineer,) and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement and accompanying drawings:-
The main objects of my invention are to rapidly generate dry steam under high
pressure within a small space or compass, and in the attainment of that end, to
promote circulation, to provide ample water surface, and to avoid the exposure of
the downward water current connections of the boiler to the fire.
It consists of certain novel features in the construction and arrangement of the
component parts of the boiler or generator, as hereinafter particularly described
and pointed out in the claims.
In the accompanying drawings like letters designate the same parts in the several
figures.
Fig. 1 is a partial vertical cross section and a partial front elevation of a steam
boiler or generator embodying my improvements;
Fig. 2 is a vertical longitudinal section of the boiler, and
Fig. 3 is a cross section of a modified form.
The boiler herein shown and described is intended principally for central
stations or places where a large amount of power has to be crowded into a small
space. At present water tube boilers are about the only ones used for such
purposes on account of the small space they occupy, as well as on account of the
high pressures at which they may be worked; but water tube boilers are neither
economical in operation nor do they give off dry steam. They lack sufficient water
surface and they are so constructed that the flame strikes cool surfaces much too
soon, making it impossible to burn bituminous coal to advantage.
To overcome these difficulties and secure the objects hereinbefore stated, is the
design of my improvements.
Referring to Figs. 1 and 2 of the accompanying drawings, A designates a fire
tube boiler similar to those in common use except that it is made of larger
diameter in proportion to its length, and is furnished with a greater number of fire
tubes a a.
It is also constructed of thick, heavy plates to withstand the high
pressure to which it is designed to be subjected. The tube heads above the fire
tubes a a, may be connected with tie rods a' a'.
B designates the furnace which may be constructed in various ways according to
the conditions and requirements under which the boiler is to be used. It is shown
as provided in the present case with a fire or bridge wall b, but this may be
dispensed with. At the rear end it opens into a flue space C which communicates.
with the rear ends of the fire tubes a a of the upper main portion of the boiler.
At their front ends the fire tubes open into a smoke box D which communicates in
the usual way with a smoke stack or chimney (not shown).
Between the furnace and main boiler shell A, I interpose a number of shells of
smaller diameter, E E, arranged transversely to the shell A, close together side by
side, which may be supported at the ends in or upon the side walls of the furnace.

page_text: These shells are made arching or higher at the center than at the ends, and are
constructed of thinner, lighter boiler plate, heing of much smaller diameter than
the main shell A and consequently able to withstand as great internal pressure even
if made of lighter material. They are connected at or near their ends by pipes F F,
and at the center or highest points therein by pipes GG with the main shell A
below the water level therein. These connections communicating with the shells E E
at different levels compel the water when heated to circulate through them and the
upper shell, thereby greatly facilitating the generation of steam, the hotter currents
with steam produced in the shells E E, passing upwardly through the central pipes G
into the upper shell between the fire tubes a a, and the cooler currents passing
thence downwardly through the side pipes F F, as indicated by arrows.
The shells E E. constituting a hollow water roof or arch over the furnace,
protect the under side of the upper shell A. and its connections with said water roof,
from direct exposure to the fire, the joints between them being closed by metallic
bars or other fire-proof material in any suitable manner. It is well known that
steam bubbles tend to form and rise from the inside of boiler plates which are
exposed on the outside directly to the action of the fire. The formation and ascent
of such bubbles in the down current connections between the main shell A of the
boiler and the water roof, would tend to retard the circulation; therefore I prefer
to exclude the fire or direct heat from the furnace from the pipes F F.
The shells E E being made of thinner plates than the main shell A by reason of
. their smaller diameter as above stated, and being exposed on their under side
directly to the fire, the water is quickly heated and partially evaporated, and
passing upwardly through the pipes G G into the upper shell A, comes in contact
with the heated surfaces of the fire tubes a a and is rapidly converted into steam,
which is given off from the extended water surface in the upper portion of said
shell A above the fire tubes. The upper shell A being of large dinmeter, affords
an extended water surface and admits of the production of dry steam.
To produce a longitudinal circulation, of the water through the boiler, the side
pipes FF en one side may be inclined forwardly, and those on the opposite side
rearwardly, as shown or the connections between the upper shell and water roof
may be staggered transversely to the boiler in any convenient way. These con-
nections may also be staggered lengthwise of the boiler to avoid weakening the
shell A.
The ends of the shells or drum E E preferably project through and are exposed
outside of the side walls of the furnace and are provided at either or both ends with
openings ee which are ordinarily closed in the usual manner by covers (not shown)
for facilitating access to the interior of the said shells and the removal therefrom of
scale and seliment which accumulates and is held in their lower ends, the arching
shape of the shells E E or water roof tending to carry and deposit scale and
sediment in their outer ends where it does not interfere with the operation of the
boiler. The central connections G G with the main boiler shell A. may also serve
for the removal of sediment.
I do not wish to be understood as limiting myself to the construction shown in
Figs. 1 and 2 of the water roof, as it may be made in various ways; for instance,
it may be constructed of plain plates like the water leg of a locomotive boiler, con-
nected and braced by tie-bolts, or it may be made of straight cylindrical shells
placed side by side lengthwise of the boiler.
In Fig. 3 illustrating a modification of the boiler in which the current takes the
opposite direction from that shown in Figs. 1 and 2 the water roof is composed of
a number of straight cylindrical shells E placed side by side crosswise between the
furnace and upper shell A. The several shells E' are connected at or near the ends
by pipes F and at the center by pipes G¹ which project and open at their lower
ends into said shells E' below the lower ends of the pipes F, thereby causing an
upward current through the side pipes F and a downward current through the
central pipes G¹ sweeping outwardly therefrom through the shells E' towards their
outer ends into which scale and sediment are carried and deposited. By thus

page_text: reversing the direction of circulation, the water roof need not be arched or made
higher at the center to avoid the deposit of scale and sediment therein over the
surfaces exposed to the greatest heat, since the outward current will sweep all
scale and free impurities into the ends of the shells E', from which they can bo-
removed from time to time through openings e e.
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 that what I
claim is :-
1. In a steam boiler or generator the combination with a fire tube boiler, a
furnace communicating with the fire tubes at one end of the boiler, and of a hollow
water roof interposed between said boiler and furnace and separating the boiler.
shell and its connections with said water roof from the furnace and flue space, and
separate up and down current connections between said water roof and boiler,...
communicating at a distance from each other with the boiler shell below the water
level therein and with said water roof at different levels, so as to induce circulation
of the water up and down through said connections and back and forth horizontally
in said water roof and boiler, substantially as and for the purposes set forth.,
2. The combination with a fire tube boiler and furnace, of an arch-shaped water
roof interposed between said furnace and boiler and having connections at or near-
the center and on each side thereof with said boiler, below the water level therein,.
said connections communicating with said water roof at different levels and at a
distance from each other, substantially as and for the purposes set forth.
3. The combination with a horizontal fire tube boiler and furnace, of a water roof
composed of shells of smaller diameter than the boiler, arranged transversely side
by side between the boiler and furnace, and having connections with said boiler
below the water level therein, said connections communicating with said water roof
at different levels and at a distance from each other, substantially as and for the-
purposes set forth.
4. The combination with a horizontal fire tube boiler and furnace, of a water
roof interposed between said boiler and furnace and having connections with said
boiler below the water level therein, said connections communicating at a distance -
from each other and at different levels with said water roof and being inclined
lengthwise of the boiler in opposite directions so as to produce a longitudinal
circulation therein substantially as and for the purposes set forth.
5. The combination with a horizontal fire tube boiler and furnace, of a water roof
composed of shells of smaller diameter arranged transversely side by side between
said boiler and furnace, and exposed at the ends, which are provided with openings
outside of the furnace walls and connections between said water roof and boiler
communicating with the boiler shell below the water level, aud with the water roof
at a distance from each other and at different levels, substantially as and for the
purposes set forth.
6. The combination with a horizontal fire tube boiler and furnace, of a water
roof composed of arch-shaped shells of smaller diameter than the boiler, placed side-
by side transversely between the boiler and furnace, and exposed at their ends,.
which are provided with openings outside of the furnace walls and connections.
between the middle or highest parts of said shells, and on opposite sides thereof and
at lower points therein with the boiler below the water level, substantially as and
for the purposes set forth.
7. The combination with a horizontal fire tube boiler having a thick cylindrical.
shell and numerous tubes extending lengthwise through it and a furnace communi-
cating with said tubes at one end of the boiler, of a water roof composed of thinner
shells of smaller diameter placed side by side transversely between said boiler and
furnace and separating the boiler shell and its connections with the water roof from
the furnace and flue space, and connections between said boiler and water roof,
communicating at a distance from each other with the boiler shell below the water
level therein, and with said water roof at different levels so as to produce a

page_text: circulation of water up and down through said tubes and boiler and lengthwise
through the shells of the water roof, substantially as and for the purposes set
forth.