Improvements in Steam Boilers and similar Apparatus.
Year: 1897

page_text: Date of Application, 2nd Mar., 1897-Accepted, 22nd May, 1897
COMPLETE SPECIFICATION.
Improvements in Steam Boilers and similar Apparatus.
I, GODFREY ENGEL, of 811-817 Pennington Avenue, South Baltimore, Anne
Arundel County, State of Maryland, United States of America, Mechanical
Engineer, 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 generally to the construction of drums and headers of
steam boilers and other similar apparatus, and particularly to a novel construction
thereof whereby a series of straight tubes, such as the generating tubes of a
tubular steam boiler, may be connected to the cylindrical or otherwise curved
surface of a drum or header, at substantially right angles to the walls of the drum
or header, at the point of connection, although said tubes are not in line with radii
of the drum or header; and the invention, while particularly applicable to tubular
steam boilers, is equally applicable to other apparatus employing drums to which
are connected a series of tubes. The invention consists in the novel construction
of the drum or header, whereby there are provided in curved walls of such drum
or header bosses, in the faces of which are apertures for the reception of tubes,
such faces being substantially at right angles to the tubes.
In steam boilers and other apparatus exposed to varying pressures and varying
temperatures, and consisting in whole or in part of a drum, usually cylindrical,
and a series of tubes connected therewith, and entering the curved surface of the
drum, it is usually necessary, in order to insure tight joints, that each tube shall
enter this curved surface at substantially right angles thereto. If the boiler has a
series of generating tubes directly connected to the curved surface of the steam
drum, this necessitates the bending of the tubes. But bent tubes are objectionable,
because it is impossible to introduce scrapers into them through their whole length
to remove scale which may have collected, and because it is impossible to examine
the whole of the interior of each tube. In replacing the tubes of such boilers,
care has to be used to obtain tubes bent to the exact curvature. To avoid the
bending of the generating tubes, manifolds or headers are frequently interposed
between the generating tubes and the steam drum, and these headers are
constructed with flat surfaces. Such a header, if arranged to receive all or a
large number of the generating tubes, is a substantially rectangular box, which
requires extensive bracing, and to be reliable, must be built up from boiler plate
and must not be cast. To avoid the use of such a header, most tubular steam
boilers are provided with a number of headers, each connecting a comparatively
small number of generating tubes with the steam drum of the boiler. But such
headers, by reason of their peculiar shape, can only be constructed economically,
in most cases, by casting, and hence are brittle and unreliable, and possess all the
other disadvantages inherent in cast metal. Moreover, the number of such
sectional headers required usually makes it necessary to provide the steam drum
with a box or saddle to receive the connecting nipples from the headers, and this
necessitates either the cutting away of the shell of the drum, thus weakening it,
or providing the drum with a cast head having a saddle cast on it. Both of these
constructions are objectionable.
The objects of this invention are, first, to so construct the drums and headers of
steam boilers and other similar apparatus having curved walls to which tubes are

page_text: to be connected, that faces having apertures for the reception of straight generating
tubes and the like, and which are substantially at right angles to the tubes, are
provided in these walls, without weakening the drums and headers, without causing
the walls to depart materially from their desired curved form, and without requiring
the use of interior stiffening braces; and second, to so construct the drums and
headers of steam boilers that while their walls retain the general curved form
which is necessary for strength and stiffness, straight tubes may be used and may
be connected to the walls of the drums and headers at substantially right angles
thereto, and the drums and headers may be constructed from boiler plate and
without internal bracing or strengthening.
These objects are attained in the invention herein described and illustrated in
the drawings which accompany and form a part of this application, in which the
same reference numerals indicate the same or corresponding parts and in
which :-
Fig. 1 is a sectional elevation of one type of boiler, employing inclined
generating tubes and cylindrical headers at the ends thereof, the front headers
being connected with a steam drum at the top;
Fig. 2 is a detail elevation of one of the headers of the boiler shown in Fig. 1;
Fig. 3 is a sectional elevation of another type of steam boiler in which the
generating tubes are directly connected with water drums at the bottom and steam
drums at the top, no headers being used;
Fig. 4 is a sectional elevation of another type of boiler in which the generating
tubes are directly connected with the drums; and
Fig. 5 is a detail transverse section of a boiler drum constructed in accordance
with this invention, the particular drum shown being arranged to receive two series
of generating tubes arranged substantially at right angles to each other.
Referring to the drawings, and first to Figs. 1 and 2 thereof, which illustrate a
form of tubular steam boiler employing cylindrical headers constructed in
accordance with this invention, 1. is the main steam drum of the boiler, 2. 2. the
generating tubes, connected at one end with a front header or headers 3. and at the
rear with a similar header or headers 4. The front header 3. is directly connected
to the steam drum 1, and the rear header is directly connected to the mud drum 5,
and is connected at the bottom to the steam drum 1. by a circulating pipe 7. In
Fig. 1 there is shown but one front and one rear header, with the generating tubes
corresponding thereto. The boiler may consist of one or more elements of this kind
joined to a common steam drum 1, and if desired, to a common mud drum 5. The
boiler is provided with the ordinary setting and with a furnace and flue chamber.
The headers 3. and 4. are cylindrical and may be formed from flat plates rolled or
pressed into shape, and riveted.
The headers 3. and 4. are provided with a number of bosses 6. corresponding
in number to the number of generating tubes connected with the header, arranged
in steps upon the curved surface of the drum and having faces at right angles to
the generating tubes in which are apertures into which the ends of the generating
tubes may be expanded. These bosses are formed by stamping or pressing the
metal sheets from which the header is made, before these sheets are connected
together. In order that these bosses may not project farther than is absolutely
necessary from the true cylindrical surface of the header, so as not to weaken the
header materially, the metal from which these bosses is formed is stamped partly
outward from the true cylindrical surface and partly inward. The bosses are
separated from each other by portions of the drum having the normal; or in this
case, cylindrical curvature of the drum. These cylindrical portions of the shell of
the drum separating the bosses prevent any deformation of the boiler when under
pressure, and hold the drum to its proper form. In Fig. 5 such a drum or header
is shown in section, the particular drum there shown being the steam drum of a
boiler having generating tubes connected with it on two sides."
In forming the bosses, as will be seen in Fig. 5, the metal is bent inward as much
as it is bent outward, the result being that these bosses do not cause the drum or

page_text: header to depart materially from the true cylindrical form, nor do they so strain
the metal as to weaken the drum or header. By this construction, however, the
generating tubes are made to enter the drum or header at right angles to the
surface thereof, thereby avoiding oblique joints or the necessity of bending
the generating tubes.
Where a row of tubes connected to the drum is substantially in line with a
radius of the drum, it is unnecessary to form in the walls of the drum bosses for
the reception of the tubes, unless the drum be of extremely small diameter. This
is illustrated in Fig. 5, in which the middle tube of each of the two sets of tubes
there shown is substantially in line with a radius of the drum and therefore is
substantially normal to the cylindrical surface of the drum. But tubes on either
side of this central tube are not in line or substantially in line with the radii of
the drum, and for their reception it is necessary to form bosses, the faces of which
are each at an angle to the curved surface of the drum, but are substantially at
right angles to the tubes.
The front header 3. of the boiler shown in Fig. 1 is provided on its front side
with a similar row of bosses to that which receive the ends of the generating
tubes, and in these bosses are hand-holes, closed in the common manner, through
which the generating tubes may be examined, cleaned, and replaced if necessary.
It is not ordinarily necessary to provide the rear header 4. with a similar series of
hand-holes, but the header is provided with a man-hole at the top, through which
it may be cleaned. The front header is provided with a similar man-hole at the
bottom.
The boiler illustrated in Fig. 1 possesses many advantages over the ordinary.
form of tubular steam boiler employing sectional headers. The headers being
cylindrical are strong and light, and being made from boiler plate are reliable and
may be made quite cheaply. The headers may be made of such diameter that
each will receive the ends of four or five or even more vertical rows of generating
tubes, so that a boiler may consist of only one or two or three of the elements
shown in Fig. 1, having therefore but a small number of parts and but few
openings into the steam drum. Moreover, because of the size of the headers,
ample room is afforded for the disengagement of the steam from the water and
a considerable water space is afforded, so that it is not necessary to carry a high
water level in the steam drum 1. or to use so large a drum as has been necessary
heretofore. When in operation, the water from the boiler circulates from the
steam drum 1. downwardly through a pipe 7. into the bottom of the header 4. and
hence upward and through the generating tubes 2. into the front header 3. and
back to the steam drum 1. again, the steam disengaging as the water rises.
In Fig. 3 is shown another type of boiler, in which the steam and the water
drums are constructed in accordance with this invention, no headers being employed.
The boiler consists of two water drums 8. 8, and two steam drums 9. 9, connected
by inclined generating tubes 10, all set within a suitable seating in which 11. is
the furnace. The furnace gases circulate upward from the grate-bars to the
drums 9. 9, and then pass downward along the inclined generating tubes 10. and
through passages formed between partitions 12. and 12. into the respective
flues 14. at the bottom. The water drums 8. 8, and the steam drums 9. 9, are
constructed in substantially the same manner as are the headers 3. and 4. of the
boiler shown in Fig. 1, and the drum shown in Fig. 5, being provided with bosses 6.
for the ends of the generating tubes, which have faces at right angles, or
substantially at right angles, to the generating tubes.
In Fig. 4 there is shown another type of boiler, consisting of three or more
water drums 14. 14. 14, and a corresponding number of steam drums 15. 15. 15,
connected in pairs by generating tubes 16. and so supported that the generating
tubes are inclined somewhat to the horizontal. The two lower steam drums 15.
are each connected with the drum above by a stand pipe 17. projecting up into
said drum. The steam drums 15. 15. 15, and the water drums 14. 14. 14, are
provided with independent bosses to receive the ends of the generating tubes 16,

page_text: .
and have faces substantially at right angles thereto, thus avoiding oblique joints
or the bending of the generating tubes. The steam drums 9. 9, of Fig. 3,
and 15. 15. 15, of Fig. 4 are provided with hand-holes opposite the ends of the
generating tubes, through which the tubes may be examined and cleaned. These
hand-holes are formed in the flat surfaces of bosses similar to those which receive
the ends of the generating tubes.
It will be observed that in all of the types of boilers herein illustrated and
described, the use of cast iron or cast steel parts exposed to steam pressure is
entirely avoided, while the boilers contain no parts of irregular shape which, if
not cast, can only be formed by elaborate and difficult mechanical processes; but
that straight tubes and simple drums may be used, and the headers or drums, which
receive the ends of the generating tubes, may be constructed almost as easily and
cheaply as plain drums.
It is not essential that the tubes connected to the drums and headers in the
manner above described shall be precisely at right angles to the faces of the
besses. A slight deviation from the perpendicular is sometimes desirable, and is
permissible to the same extent that it would be permissible if the tubes were
connected to a flat-sided tank. For this reason, it is stated in the following
claims that the tubes are substantially at right angles to the faces of the bosses.
The drawings of this application show the connection of tubes with the sides
of cylindrical drums and headers. It is obvious, however, that the invention is
not limited in its application to the connecting of tubes with the sides of cylindrical
drums, but that tubes may be connected to any curved surface in precisely the
same manner, by forming in such surface bosses, the faces of which are substantially
at right angles to the tubes. The ends of drums frequently are formed from
wrought iron, steel, or similar metal, and have a spherical or approximately
spherical form, in order to secure strength and stiffness without the use of internal
braces. If it be desired to connect tubes to the heads of such drums, the heads
may be provided with bosses similar to those with which the drums and headers
illustrated in the drawings are provided. The invention, therefore is not limited
to the connection of tubes to the sides of cylindrical drums and headers, but is
applicable to the connection of tubes to curved surfaces generally.
Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, I declare that what 1
claim is :-
1. A drum for steam boilers and similar apparatus, adapted to be directly
connected to a series of tubes, having a curved surface, and having in said surface
a series of bosses, the faces of which are provided with openings for the reception
of the ends of the tubes and are substantially at right angles to their tubes, said
bosses being arranged in steps upon the surface of the drum, and being separated
from each other by curved portions of the drum, by which the form of the drum is
retained, substantially as described.
2. A drum for steam boilers and similar apparatus, adapted to be directly
connected to a series of tubes, and consisting of a generally cylindrical drum, in
the cylindrical surface of which are a series of bosses having faces, which are
provided with openings for the reception of the tubes and are substantially at right
angles to their tubes, said bosses being arranged in steps upon the cylindrical
surface of the drum and being separated from each other by cylindrically curved
portions of the drum, by which the form of the drum is retained, substantially as
described.
3. A drum for steam boilers and similar apparatus, adapted to be directly
connected to a series of tubes, and consisting of a generally cylindrical drum having
stamped in its sides a series of independent bosses projecting partly inward and
partly outward from the cylindrical shell of the drum, and having faces which are
provided with openings for the reception of the tubes and are substantially at
right angles to their tubes, said bosses being arranged in sieps upon the

page_text: cylindrical surface of the drum and being separated from each other by
cylindrically curved portions of the drum, by which the form of the drum is
retained, substantially as described.
4. In a boiler, the combination, with a series of generating tubes, of a drum
adapted to be directly connected to said tubes, having a generally cylindrical form
and provided with a series of independent bosses, the faces of which are provided
with openings for the reception of the tubes and are at substantially right
angles to their tubes, said bosses being arranged in steps upon the cylindrical
surface of the drum, and being separated from each other by cylindrically
curved portions of the drum, by which the form of the drum is retained,
substantially as described.
5. In a boiler, the combination, with a steam drum and a series of inclined
generating tubes, of front and rear headers for connecting said tubes at the front
and rear to each other and to the steam drum, said headers being generally
cylindrical in form, and having in their sides series of independent bosses, the
faces of which are provided with openings for the reception of the tubes and are
at substantially right angles to their tubes, said bosses being arranged in steps upon
the cylindrical surface of the drum, and being separated from each other by
cylindrically curved portions of the drum, by which the form of the drum is
retained, substantially as described.
1000
JOHN WAUGH,
Agent.