Year: 1887

page_text: I, ISAAC MCKIM CHASE of Washington, Columbia United States of America,
Pattern 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 :-
My invention relates to steam generators, and has for its object the construction of
a generator in which steam can be raised very rapidly, a high degree of pressure
carried, the maximum of heating surface obtained and the number of joints subject to
leakage reduced to the minimum.
In the generation of steam, only the sensible heat of the steam is available for
producing external work, the latent heat being required for the internal molecular
work, and while so employed is not available for any other work; and as the latent
heat decreases, and the sensible heat increases with the increase of pressure, it is more
economical to work steam at a high degree of pressure than at a low degree. Many
generators have been devised for carrying steam of high pressure, but they have
generally been a complication of coils or pipes and manifolds. The measure of the
force of the circulation of the water in a boiler is the "head or the difference in the
weight in the ascending and the descending columns of water. In the coil or
circuitous pipe system, the circulation of the water is seriously impaired by the
friction produced by the sides of the pipes; and in some instances the friction is so
great that the "head" is overcome, and it becomes necessary to force the circulation
with a pump.
"
When a globule of steam is formed, the quicker it leaves the water the more rapid
will be the circulation, and the faster will steam be generated; and for every degree
the globules are required to depart from a perpendicular path to reach the steam
space, the circulation is correspondingly impaired.
In the cylindrical marine boiler with internal furnaces, the practical limit of
thickness of metal has been reached, both in shells and furnaces. In the transmission
of heat through metal plates, time is an important factor, if the plate is thick the
temperature of the two sides may vary considerably, owing to the time required for
the heat to pass through the metal, and as a consequence, it has been found in practice
with very thick furnaces that the metal wastes away rapidly.

page_text: By my invention a steam generator of great structural strength is produced, and
which can be made a safety boiler by proportioning the volume or capacity of the
section to the thickness of metal and the pressure of steam required; and in which a
natural and free circulation of the water is effected.
The invention will be hereinafter described and particularly pointed out in the
claims.
In the accompanning dramings which form a part of this specification—
By my invention a steam generator of great structural strength is produced, and
which can be made a safety boiler by proportioning the volume or capacity of the
section to the thickness of metal and the pressure of steam required; and in which a
natural and free circulation of the water is effected.
The invention will be hereinafter described and particularly pointed out in the
claims.
In the accompanying drawings which form a part of this specification—
Figure 1 represents a front elevation.
Figure 2 a vertical transverse section on the line 2, 2, of Figure 3.
Figure 3 a longitudinal section on the line 3-3 of figure 2.
Figure 4 is an enlarged end view of one of the inner sections of the generator.
Figure 5 is a plan of a blank for forming a section.
Figure 6 is an edge view of the blank.
Figure 7 is an end view of a section showing a modified construction.
Figure 8 is a longitudinal section on an enlarged scale through one of the sections
of the generator, between the manifolds, and
Figure 9 is a longitudinal section through two generators set end to end.
Reference being had to the drawings and the letters marked thereon, A represents
a furnace provided with grate bars of usual construction. B, C, represent the outside
sections, which at their lower ends each rest upon iron supports a, and form the sides
of the furnace. D, E, F, and G, are the intermediate sections, which are suspended
directly over the furnace. Each of the several sections is composed of a series of
vertical tubes b, which communicate with a manifold H at their upper ends, and a
similar manifold I, at their lower ends. The several sections constituting the
generator are connected by a transverse feed reservoir J, at their front ends, and by a
mud drum K, at their rear ends. From the upper manifold H of each of the
intermediate sections, a pipe c connects with the steam drum L, and the outer sections
are connected to the drum by pipes d, d. In the upper manifold H, and immediately
over each vertical tube b, is formed a hand hole e, for cleaning said manifolds.
Each section of the generator is formed of one continuous sheet of metal, such as
shown in the blank in Figure 5, which is made by heating, or not heating a sheet of
metal, (as steel, iron or copper may be used) placing it upon a suitable form, and by
the use of dies or swages the corrugations g, and the longitudinal indentations h, are
formed. The blank is then bent over a mandrel at its central indentation h and the
lower manifold I formed, as shown in Figure 4. At the free ends of the section a
casting i, having the hand holes e is inserted, and to which said ends are riveted as
shown at k, l, in Figure 4; a "chock" m is also inserted at the ends of the manifolds
to form a circle to receive the ends of the cast-metal pipe section M, and the "chock"
is then properly caulked, after said sections have been secured to the manifolds. The
front end of each of the manifolds H, is closed by a head N, and in the rear end of
each is set a hand hole plate O. The sections forming the generator are riveted
between each of the vertical tubes b, in the usual manner, as shown in
Figures 3 and 8.
In the modified construction shown in Figure 7, the casting of Figure 4 is
omitted, and a common lap joint or seam o is formed in the upper manifold P. In
this construction, it will be observed that an additional set of vertical tubes p, and the
manifold P, are provided; the object of which is to provide additional water space for
marine boilers which are subject to the effects of the rolling of the vessel, and
consequent abnormal displacement of the water in the boiler.
As another pre-
cautionary measure to keep the water at the same level in the several sections
constituting the generator, the feed pipe Q is enlarged and forms a reservoir J,
affording a head to the water in the section, and serves to supply all of the sections
regularly, irrespective of the differences in evaporation, due to the fact that some of
the sections are exposed to more intense heat than others and consequently require a
greater supply of water.
The sections B, C, D, E, F, and G, having been formed as described, they are set in
position upon a front R, which is a casting lined with fire brick, as shown at q, in

page_text: Figure 3, and a rear casting r. The bridge wall S is then built, and has an air duct T
formed in it, which is provided with a suitable damper or valve (not shown). Above
the front R, the space is filled with fire clay, with a piece of sheet metal in front of it;
and the spandrels between the manifolds H are filled with a suitable refractory
material w; also at the rear end of the furnace the space above the masonry is filled
with molded fire clay forming a baffle plate U, which extends up and forms the lower
wall of the calorimeter or throat V of the furnace leading to the uptake W. The
throat is also provided with a damper s, to regulate the draft of the furnace.
Air entering the duct T is discharged through an expanded orifice t, on the
underside of the baffle plate U, passes forward and mingles with the gases emanating
from the burning fuel, and supplies additional oxygen to the gases to complete their
combustion. It will be observed that air entering through the duct T is heated before
it enters the furnace and is discharged in a thin sheet or strata over the bed of burning
fuel, thereby becoming thoroughly mixed with the gases before they pass through the
throat V of the furnace to the up-take. The baffle plate U, may be extended farther
forward in the furnace as circumstances require.
The manifolds I of the outer sections B, C, are connected to the reservoir J, by
pipes u, and to the manifolds H, by pipes v, to supply them with water and to keep up
a circulation within said section; and the rear ends of said manifolds are connected to
the mud-drum K, by pipes y. The steam drum L, is provided with a pipe x, for
discharging water of condensation, which flows into one of the manifolds H.
In Figure 9, two generators are shown connected to one up-take. It is obvious the
generators may be multiplied according to the purposes to which they are to be
applied, and the quantity of steam required for the work to be done. One great
advantage of this construction is, that any one of a set of generators can be shut off
from the others and be repaired while all of the other generators constituting the set
are in use; this can be accomplished by simply closing the throat V, of the furnace of
the generator requiring repairs by the use of the damper s.
It will also be observed that in the generator shown, there are no sharp angles;
that when globules of steam are formed in the section, they pass directly up through
the body of water into the steam space of the upper manifold unobstructed; that any
one of the vertical tubes b may be inspected or cleaned through its handhole e,
and the manifolds by the removal of the heads N or f. The sections may be made
of steel, iron, copper, or any other metal having sufficient tensile strength to bear
a high degree of pressure of steam; steel, however, is preferred. There are no
joints or seams exposed to the heat of the furnace. Each section being composed
of one continuous sheet of metal of the same thickness throughout there are no
variations in the expansion and contraction of the metal, consequently no unequal
strains are brought to bear upon the generator.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed I declare that what I claim is:—
First. A blank for boiler sections made of sheet or plate metal, having longitudinal
indentations and transverse corrugations connecting with said indentations formed in
it, substantially as described.
Second. A boiler section constructed of sheet or plate metal having its manifolds
and connecting tubes formed integral, substantially as described.
Third. A boiler section having an upper horizontal manifold, a lower inclined
manifold with intermediate connecting tubes formed of sheet or plate metal, the tubes
and the manifolds being integral, substantially as described.
Fourth. A boiler section having its manifolds and connecting tubes formed of one
continuous sheet or plate of rolled metal, substantially as described.
Fifth. A boiler section constructed of sheet or plate metal having its manifolds and
connecting tubes formed integral, in combination with a separate plate of metal
secured to the ends of the sheet forming the section, and in the upper manifold, and
provided with a series of apertures over the connecting tubes, and detachable covers
for said apertures, substantially as described.

page_text: Sixth. A steam generator composed of sections of different areas of heating surface,
and provided with upper and lower manifolds, in combination with a feed water
reservoir connected to both of said manifolds, in each section, substantially as
described.
Seventh. A steam generator composed of sections of different areas of heating
surface and provided with upper and lower manifolds, the outer sections forming the
sides of the furnace, and the intermediate sections suspended over the grate surface, in
combination with a feed water reservoir connected to both manifolds of each section,
and a steam drum in communication with each section by a separate pipe, substantially
as described.
Eighth. A steam generator composed of sections, the outer sections forming the
sides of the furnace, in combination with a hollow bridge wall, a baffle plate forming
the lower wall of the throat of the furnace, and an air distributing orifice under the
baffle plate, substantially as described.
Washington, D.C., April 29th, 1887.
ISAAC MCKIM CHASE.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.