Note: Descriptions are shown in the official language in which they were submitted.
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2044282 :
BOILER CAP~BLE OF BURNING LIOUID OR GASEOUS FUEL .
The present invention relates to a boiler suitable
for burning liquid or gaseous fuels as described in the
preamble to the main claim. ;
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Boilers of the above-mentioned type are Xnown and
u~ed in a variety o~ configurations which, although differing
in detail, operate generally according to the same principle.
The prior art boiler design presently being considered applies
generally to boilers constructed of steel plate or cast iron.
Boilers constructed of the latter normally comprise relatively
narrow individual elements which are cast as a single piece by
means o~ the hollow casting method (see DA-A-20 17 992 and FR-
A-22 37 141), and regularly exhibit nipple-like projections
which face the water jacket of the boiler to form zones of
relatively narrow ~low passages. They are assembled into a
structure comprising a plurality of individual members. The
rationalized serial production of prior art cast iron boilers
entails considerable technical expenditure, particularly given
the requirement that individual parts, or rather the cast
elements, must be hollow cast. Most of the binders used to
bind together the core foundry sand, which is essential for
the production of cavities found in boiler parts, are highly
toxic. Due to its toxicity, the sand used for the core and
left over at the end of the casting process, can not normally
be disposed of in conventional waste sites. The excess core
sand must be disposed of in special waste sites, a procedure
that incurs higher costs and entails greater logistical
complexity. The production of cast iron boilers comprising a ;
plurality of individual members, that are open only at their
small nipple-shaped apertures, involves relatively high
foundry material costs. Such prior art cast metal boilers are
also necessarily heavier than boilers produced by other
methods.
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The object of the present invention therefore
relates to the improvement and creation of a boiler of the
kind first described type, whose essential parts, i.e. those
constituting the firebox, can be produced from a material that
S functions to inhibit condensation. It is also proposed that
such parts, which comprise cast iron, be cast by means of a
coreless method that is both rational and environment-
friendly. The method of production of the present invention
would furthermore permit the boiler to be assembled from only
a few elements and permit the consideration of ceramic-based
material ln the manufacture of those parts that surround the
~ombustion chamber.
The object of the present invention is addressed in
a boiler of the first mentioned type which comprises the
di~tinguishing features that are claimed in the distinguishing
portion of Claim 1. Further advantageous improvements will be
described in the subsidiary claims.
In contrast with prior art boilers, which comprise
relatively thin individual members cast in one piece by the
hollow casting method and comprise nipple-like constrictions
on the side facing the water contained inside the water
~acket, the proposed boiler is designed from geometrically
very gimple parts that are manufactured by a simple method ~;~
that permits a ~eal formation without nipple formation and
which ~oined together to form a firebox. It is furthermore
proposed that the shell that encloses the water jacket from ;
the outside be constructed simply from plate steel. The
simplified geometry of the boiler elements permit coreless
casting, which replaces the entire hollow casting process,
eliminates foundry sand disposal and affords a simplified
means producing individual members whose thickness far exceeds
that of boiler elements that can be produced by conventional
casting technology. The coreless casting method permits cost-
effective and advantageous manufacture of different types of
boiler members that are distinguished in particular by -
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2044282
improved pressure resistance, thinner design, and a simplified
and principally uniform design of the end members. Further
advantages are described in greater detail in the subsidiary
claims .
The novel design of the proposed boiler permits use
of a coreless method for casting the boiler parts permitting
conetruction of an inner water-conducting cavity which, rather
than being sectioned off by means of small and narrow flow
through passages, corresponds effectively to a conventional
fiteel boiler. By always using the same rings and
corresponding end members, it is possible to assemble the
lndlvldual cast elements into boilers of different lengths.
In order to be able to cast the members in "green" sand, the
members, which are aligned vertically inside the casting ;
mould, must have a conical shape that permits a positive model
to be wlthdrawn from the sand form prior to casting the final
product. The simple geometry of the rings permits their
manufacture from ceramic material. Because the outer wall of
the water-conducting cavity comprises an easily-manufactured
steel plate jacket, the rings can have a simple geometry.
The proposed boiler and advantageous improvements
thereof will further be aescribed in greater detail with the
ald of drawings of one embodiment example. Schematically
lllustrated are:
Flg. 1 is a longitudinal section through the proposed
boiler;
Fig. 2 is a cross section through the proposed boiler;
Fig. 3 is an enlarged detailed section in accordance with
circle A of Fig. 1 and
Fig. 4 is an enlarged detailed section of the preferred
configuration of the steel-plate jacket packing--system.
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The proposed boiler comprises a water-conducting
housing 3 comprising feed and return connections 1 and 2.
Said housing surrounds a firebox whose openings, which are
situated at both ends of the boiler, are provided with closure
device~ 6, 7, where device 6 contains the opening through
which burner 9 is installed, while the other opening contains
a flue gas outlet. In its basic configuration, the proposed
boiler comprises a water-conducting housing 3, which comprises
two end members 10 and one or more rings 11 that form the
combuskion chamber wall 4', and a steel plate jacket 12 that
~urrounds a water-conducting cavity 13 from the outside.
8teel plate ~acket 12 and rings 11 are immobilized between end
member~ 10 by means of tightening rods 14 that extend through
cavity 13. The tightening rods, which are attached to end
members 10 so as to form a seal therewith, are distributed
unlfor~ly around the circumference of the boiler housing. The
onlarg~d detail shown in Figure 3 better illustrates the means
by whlch tightening rods 14 are secured to end members 10 to ;~
form a ssal therewith. In addition, all impact points located ;
b~tween ~teel plate ~acket 12, between end members 10 and
rings 11, and between the rings 11 themselves, are provided
wlth packing means 15. This arrangement is demonstrated more
clearly in Figure 3, whe~ein packing means 15 are shown in the
form o~ a spring-and-groove arrangement comprising packing
rings 17 arranged inside grooves 16. In the configuration
~hown, rings 11 and both end members 10 are cast. Rings 11
are provided on the side facing the firebox with longitudinal
ribs 18. It is essential that such parts be cast with a
elightly conical shape so as to facilitate the creation of ; ,
positive models in the foundry sand wherever required by the
particular design of the part being cast. This process need ~ ~
not, however, be disclosed in greater detail. It will, in any ~ -
case, be readily appreciated that, since rings ll and the end
members do not comprise cavities, they can be formed without -
use of foundry cores. In order to be able to comfortably - ;~;
mount closure device 6 that is embodied as a locking door ~ ;~
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which mounts burner 9, and in order to house insulation block
6' which is attached to such locking door, burner-side end
member 10 is, as illustrated, provided with an annular
connecting collar 19 which, as can be seen, also has a
slightly conical cross section. The other end member 10,
which faces the outer side and features flue nozzle 20, is, as
illustrated, essentially configured as a slightly convex disc.
In this arrangement, however, only the wall of connecting
nozzle 20 has a slightly conical shape. Since casting of
these elements produces casting irregularities, any impact-
prone elements must be surface-ground. The provision of
tightening rods 14, as illustrated in Figure 1, is sufficient
to seal off the water conducting cavity 13 both towards the
inside facing firebox 4 and towards the outside. Such sealing
1~ accomplished simply because tightening rods 14 immobilize
both end members 10, rings 11, steel plate jacket 12, which is
mads endless by means o~ a longitudinal welding bead, and
p~cking devices 15, which are installed at various places
throughout the st N cture. It is, however, also possible to
move tightening rods 14 closer to the rings in the radial
direction and also, as indicated by the broken lines, to
install additional tightening rods 14' further towards the
rim. For this purpose, however, end members 10 must, as
indicated by the broken lines, be diametrally enlarged in
order to be able to provide circumferential rims that project
beyond steel plate jacket 12 (See Figure 2) to which
tightening bars 14' can be secured.
Apart from the arrangements described above, all
that remains to be cast are connecting extensions 22 (See
Figure 2) are then function to serve as bearing sites for
outer tightening rods 14l. Since the process of attaching
feed and outlet lines 1, 2 to the steel plate jacket 12 is
amongst the simplest of operations, these are, as indicated by
means of broken lines, preferably attached to steel plate
jacket 12. Since rings 11 possess a very simple geometric
form and because of the principle enunciated in-the present
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disclosure of joining the rings together by tightening the
latter between both end members 10, it is possible to
manu~acture the rings from ceramic material since this
material has properties that favour resistance to condensation
to a greater extent than cast iron. If such ceramic parts or
ceramic rings are not extrusion-moulded, but rather are
Compres~ion-moulded~ it is necessary for sufficient conicity
to be designed into such parts. The above-described design
principle can, o~ course, be applied to the production of
gravlty-operating boilers which, rather than featuring a pot-
shaped combustion chamber 23', comprise a combustion chamber
in~ert that opens toward the bottom. Such a configuration
would reguire merely a suitable redesign of end members 10,
~ince the escaping flue gases would, in such a configuration,
have to be drawn o~ in the zone of the end member 10 nearest
tho burner, a~ter which such gases would be directed to the -~
zone o~ the other lower-end member and then be directed toward
the top in a ~lue gas stream o~ annular cross section.
Since the thermal loads encountered on the firebox
wall 4'di~er ~rom those acting on steel plate jacket 12, such ;~
parts exhibit di~erent degrees o~ thermal expansion. Steel
plate jacket 12 i9 separated ~rom other parts through the use
o~ the packings described in Figure 4, i.e. steel plate jacket
12 sits so as to be able to slide and is provided on at least
one side with a packing ring 15' that sits in a corresponding
groove 23 o~ end members 10. ~ ;~
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