Improvements in Steam Boilers and Furnaces therefor.
Year: 1888

page_text: Date of Application, 25th July, 1888
Specification Accepted, 19th Oct., 1888
Improvements in Steam Boilers and Furnaces therefor.
We, NATHAN BEACH CLARK, Chief Engineer United States Navy, (retired),
residing at the City of Washington, District of Columbia, United States of America,
and FRANK BOCKIUS KING, Naval Architect, residing at Baltimore, in the County of
Baltimore and State of Maryland, one of the United States of America, 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 general idea of the boiler is that the shell shall be composed of segmental parts
above and below, with their flat faces toward each other, the upper and lower
members connected by water tubes around which the hot gases circulate. The
escaping gases of combustion are utilized to heat the air fed to the furnace, by passing
through narrow channels in the heat interchanger, the air being forced through
alternate channels to the fire.
Referring to the drawings:
Figure 1, is a side elevation, partly in vertical longitudinal section, of a boiler
illustrating the invention.
Figure 2, is a vertical cross-section, about on line, x, x, Figure 1.
Figure 3, is a front elevation, and partial cross-section of a battery of boilers, the
heat interchanger being in section.
Figure 4, is a plan, showing the arrangement of heat interchanger in relation to a
battery of four boilers parts being broken away, and parts shown in horizontal
section.
Figure 5, is a cross-section of same, about on line, y, y, Figure 4.
Figure 6, is a top plan, partly broken away, showing the relative arrangement of
tubes and down passages, and indicating the construction of furnace casing.
Figure 7, is a plan, partly broken away, of the fire grate and supports.
Figures 8, 9, 10, and 11, are details showing the construction of furnace casing.
Figures 12, 12, and 13, are front diagrammatic views of hoilers, showing different
forms of shell and method of assembling.

page_text: Figure 14, is a section on line, 2, 2, Figure 15.
Figure 15, is a side elevation--partly broken away, of a modification wherein the draft
is first between the water tubes, then downward and around the lower boiler member.
Figure 16, is a perspective of end of interchanger.
Figure 17, is a longitudinal section of interchanger enlarged in the direction of
expansion and heated gases.
Figure 18, is a plan of the interchanger broken in the middle, the right hand
portion being a section on line, A, B, Figure 19.
and
Figure 19, is a section through the interchanger showing modified construction,
Figure 20, is an end view of the interchanger broken in the middle, the part
to the left of the break being a section on line, C, D, Figure 19.
The boiler sections, A, consist of segmental portions, 1, forming an arched shell
The shells are connected to flat tube sheets, 2, by a stay or stays, as by a per-
forated plate, 3, which is riveted or otherwise secured to flanges, 4, on the arched
plates and tube sheets.
The arches, 1, are also connected to side plates, 5, which with inner plates, 6,
form the inclosing walls of a water leg or box, 7, (see Figure 2). Where a
number of segments are united there may be any desirable number of these water
boxes, which serve as downflow pipes, the water tending down therein by reason
of their large area.
The plates, 6, are tied to plates, 5, by bolts, 8, or in any other usual manner,
and are firmly fastened to flanges on plate, 2, and at the lower edge to a corre-
sponding tube plate, 9.
The lower edges of plates, 5, are bolted, riveted, or otherwise secured to the
heads of segmental water shells, 12, 12. These segments, 12, may run in a direction
at right angles to the segment, 1, and are held to tube plate, 9, by suitable fastenings,
preferably by riveted flanges.
The boiler shell, then, has the general appearance shown in the drawings, a number
of segmental shells running lengthwise at the top, a number of similar shells at the
bottom running lengthwise or crosswise and approximately flat tube plates forming
the top and bottom of a space between said members, the side walls of said space
forming water connections or boxes.
The space or chamber, 13, between the tube sheets, 2, and, 9, contains a large
number of small water tubes, 14. These tubes are inserted from inside the top
arches, and the ends oxpanded to hold them in place.
A shield, 15, extending out over the tubes, and a little distance above the upper
ends thereof, may be used to prevent priming.
Steam pipes, 20, connect with the top of the steam spaces in the arches, 1.
Each lower segment or shell, 12, has a mud cup, 21, which is a depression in
the walls of the shell. The tube 22, opens in proximity to the mouth of this cup,
and serves as a blowoff pipe.
The tubes, 14, are surrounded by flame and smoke, and are liable to become foul.
To clean them we provide what may be called a steam brush consisting of tubes, 26,
These
extending across the boiler, and provided with frequent perforations.
tubes, 26, rest in bearings, and can rotate therein. The tubes have swivelled
connection with pipes, 27, which are controlled by valves, 28. A handle, 29
serves to rotate each tube, 26, on its axis.
By turning handles or cranks, 29, the tube, 26, may rotate. A jet of steam,
water, or air passing from pipes, 27, through the pipes, 26, and perforations, will
be thrown against the surface of tubes, 14, to cleanse them, and the rotation of
pipes, 26, will throw the jets in all directions.
One end, 33, of arched section, 1, may be spherical. The other end, 34, may be a
portion of an arch placed at a right angle to the arch, 1, itself. By either
arrangement the bracing of the ends is avoided. By preference the top member,
overhangs the bottom members, 12, 12, to give free entrance to the gases betweer
the tubes, 14.
1

page_text: The door or deflector, 38, and the deflecting plate, 39, Figure 1, form part of the
trunk which leads the hot gases away from the boiler to the interchanger.
The furnace casing, 40, is preferably composed of corrugated metallic plates, 41,
and, 42, the corrugations in those plates running in different directions and the
adjacent plates being connected by rivets, 43. The casing is further lined by an
asbestos packing, 44, which is held in place by a sheet, 45, of woven asbestos, the
whole being tied by bolts, 46. The bolt heads, 47, are covered with asbestos cover-
ing, 48, firmly secured thereto, and the nuts, 49, may rest against rounded washers,
50, so as to fit the corrugated outer surface of the casing. (See Figures 8 to 11.)
The grates are supported on the tubes, 50, which are connected to the feed pump, so
that a continuous stream of water is driven through the tubes, and the bars, 52, are
thereby kept comparatively cool. The sides of the furnace are lined with soapstone
slabs, 53, sawn to present end grain to fire, and by preference a space is left between
the same and the casing, 40.
There may be any number of top segments in combination with any number of
inverted bottom segments, disposed either parallel to, or at right angles to each
other, with any number of tube chambers with intervening downcast water conduits.
Small boilers having not more than two bottom segments should have the same
parallel with the top, but where there are more than two bottom segments, it is best to
arrange them at right angles to the top, in order to secure an unobstructed circulation
of water.
In Figure 15, the overhang of the top member is shown at the front of the boiler,
and the direction of the draft is indicated by arrows.
It will be understood that various modifications of the boiler can be made on
the general plan of several segments or arches connected by tubes and water legs or
boxes.
The forced draft about to be described gives enormous capacity for coal combustion
per square foot of grate surface. The grate, therefore, by means of the water pipes
has special provision for its protection. The asbestos lined casing permits very high
temperatures in the furnace without injury.
The heat interchanger, so-called, is a device for heating the air as it is fed by forced
draft to the furnace, by absorbing the heat which would otherwise be carried off with
the smoke and gases of combustion.
The general idea of the interchanger is a box divided into very narrow compart-
ments by thin plates, preferably metal and good conductors of heat. Cold air is forced
in one direction toward the furnace through alternate compartments, while the smoke
and gasos from the furnace move in the other direction through the other compart-
ments. Thus the air as it goes in comes in close proximity to gases which are hotter
toward the furnace, and gases as they become cooler constantly approach a part of
the interchanger in which the air is also cooler. By causing the hot gases and fresh
air to flow through alternate passages in opposite directions the extremes of temperature
are opposed to each other, resulting in a complete interchange of extremes of tempera-
ture between the hot gases and fresh air. But the gases may be passed through the
interchanger in the same direction, or one set of currents may pass lengthwise and
the other set crosswise of the interchanger.
The interchanger casing, 60, may be rectangular trapezoidal, or of other form, and
is a box with hinged sides or covers. By preference all the top and bottom plates, 61,
are hinged so that access can be had to the compartiments for cleaning.
The space within the casing is divided longitudinally by thin plates, 62, 62. These
plates are preferably of inetal, and the alternate passages between them are closed
at the ends in such a way as to keep the two circuits distinct. This may be done
by bending the ends of proximate plates toward each other, and riveting or
otherwise fastening them as at, 64, thus leaving alternate passages open at
the ends, while the other passages are there closed. Air is forced through alternate
passages toward the furnace, while hot gases flow in the other passages, from the
furnace.
.
By preference the gas passages are closed at one end and open at the top of the

page_text: interchanger at the end farthest from the furnace, while the air passages are open at
the end, (see Figure 16,) but this arrangement can be varied. A reverse alternation
may be made at the end toward the furnace. (See Figure 19.)
The passages between the plates, 62, may be cut off by partial partitions, 65,
(Figure 19) which partitions also serve as spacing bars and cause the passing
currents to move in serpentine directions. The feathered arrows, Figures 3 and 19,
show the direction of outflowing gases and the unfeathered arrows the course of the
incoming air.
Injector blowers, 70, or any other air forcers may be used to drive air through the
interchanger.
As shown in Figure 3, the air is forced by blowers, 70, into passages, 69, thence
shrough the alternate passages of the interchangers, F, F, to the trunks, G, G, fig. 4
from which trunks the air is fell to the furnace at a very high temperature.
The smoke and products of combustion entering the interchanger from passages, H,
go through the alternate passages in the interchanger and escape by passages, I,
to the chimney or smoke stack, nearly all the heat having been absorbed by the
inflowing air.
The rapid expansion of the inflowing air in the narrow passages may be provided
for by enlarging such passages toward the furnace. (Figure 17.) The reduction
of the volume of gases due to cooling permits that the gas passage be reduced
at the same end of the interchanger where the narrow parts of the air passages
occur.
The passages can be readily cleaned of soot by dropping the lower lids, 61, Figures 3
und 19 and if necessary passing brushes between the partitions.
When the temperature of the hot gases is too high for metallic plates to resist it is
proposed to construct it in two sections, the passages of the hot end being divided by
thin plates of soapstone, firebrick, solidly compressed asbestos, or other refractory
substance which would serve to subdue the intense heat before the gases reach the
metallic plates.
The edges of the plates of the interchanger rest upon asbestos gaskets, thereby
making tight joints with the casing. The hinged doors are also lined with asbestos or
similar material for the purpose of making gas-tight joints between thein and the edges
of the plates.
Air currents may be forced through spaces in the furnace casing, to keep the same
cool, and the air thus fed through may be carried directly to the furnace.
The feed water passing through pipe, 50, will protect them, and also the fire grate
by absorbing the heat.
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. A steam boiler of the described character composed of segments or arches with
their flat faces toward each other and having side water passages and water tubes of
the general character hereinbefore stated.
2. In a steam boiler of the character described, a number of arches or segments
side by side attached to a tube plate and having the edges stayed thereto and having
circulation passages for steam and water substantially as described.
3. A steam boiler consisting of a number of top segments or arches placed longitu-
dinally, a series of inverted arches or bottom segments placed transversely, water
connections from the sides of one set to the ends of the other set of arches, and water
tubes between the same.
4. In a steam boiler of the character described having water tubes between the top
and bottom member, a movable perforated pipe in proximity to these tubes and
connections to the pipe whereby a steam or other blast may be introduced to clean the
water tubes in the manner described.
5. The furnace casing of corrugated plates having asbestos lining and supports of
the general character hereinbefore described.

page_text: 6. The heat interchanger consisting of a casing divided by thin plates into narrow
compartments and having means to force air through alternate compartments while the
hot gases from the furnace pass in the intervening compartments substantiatly in the
manner described.
7. The heat interchanger consisting of a casing divided by thin plates into
narrow compartments of unequal sectional area at their ends, and having means for
feeding air and gases through alternate compartiments, and movable covers to said
compartments.
NATHAN BEACH CLARK.
FRANK BOCKIUS KING.
Per Jensen & Son,
77, Chancery Lane, W.C.,
Patent Agents.