Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02279082 1999-07-28
Martin GmbH fur Umwelt-
und Energietechnik
our ref.: 001/99/
CHARGING DEVICE
The invention relates to a charging device for
incineration and gasification plants, in which the
combustible material can be introduced into the plant
from a feed hopper via a feed table by means of at
least one charging element.
Known charging arrangements have the function of
introducing the combustible material in a metered
manner into an incineration or gasification plant. For
this purpose, use has previously been made of a box-
shaped charging piston or a number of such charging
pistons which, supported on a plane feed table, is or
are moved to and fro so as to convey the combustible
material onto a combustion grate or into an
incinerator. However, these charging devices have the
disadvantage that the piston has very large rectilinear
sealing surfaces which are intended to prevent
combustible material being unintentionally drawn into
the region behind the charging pistons. Straight
sealing faces are, however, particularly difficult to
produce, above all when such a charging piston is
additionally subjected to thermal loads. At the front
reversing point of the piston, that is to say when the
piston is located in the end position close to the
combustion chamber or the gasification chamber,
considerable thermal radiation occurs on the front part
of the charging piston. In the case of large charging
pistons, this heating leads to non-uniform heating
action and thus to distortions which can lead to
serious lacks of sealing. If, as a result of such
distortions, combustible material penetrates behind the
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charging piston, the latter may even become mechanically
blocked.
Particular difficulties always arise when the
charging device is also to be sealed against gases entering
or escaping. This is necessary in particular in
gasification plants in which the fuel is not reacted
completely but in which a gas mixture is produced which is
still combustible and perhaps even toxic.
The object of the invention is to provide a
charging device which, by virtue of the constructional
design of the charging element, makes possible simple and
reliable sealing, in particular with regard to gas exchange.
According to the invention, this object is
achieved in a charging device of the type described in the
introduction in that the charging element comprises a thrust
part for moving the combustible material and at least one
guide part, the shape of which is circular-cylindrical and
which is guided in a guide arrangement, and in that the
guide part extends through at least one sealing arrangement
adapted to it of the charging device. This embodiment
ensures that at least that part of the charging element
which interacts with a seal has a circular-cylindrical
structure so that a circular seal can be used which is not
only simpler and cheaper but also considerably more
effective than seals for plane surfaces.
In one aspect of the invention, there is provided
charging appliance for combustion and gasification
installations, in which the fuel can be brought from a feed
hopper over a feed table into the installation by means of
at least one charging element, said charging element
comprising a thrust part, which is subjected to the
atmosphere of the combustion and gasification installation,
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for moving the fuel and a guide part which has a circular
cylindrical shape and is guided in a guide arrangement, and
wherein the guide part penetrates through a seal
arrangement, characterized in that the charging element is
configured overall as a circular cylindrical piston with
equal diameters for the guide part and the thrust part, and
in that the seal arrangement also interacts with the thrust
part.
According to a preferred embodiment of the
invention, the charging element is as a whole designed as a
circular-cylindrical piston. In such an embodiment, the
sealing arrangement is intended both for gastight sealing
and also to prevent the penetration of combustible material
into the space located behind the thrust part. Not only
does such an embodiment have the advantages relating to a
circular seal, but, on account
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of the circular-cylindrical shape of the entire
charging element, it is also possible to provide a
number of such seals one behind another. Moreover, the
production of such a charging element is relatively
simple because circular-cylindrical shapes are easier
to produce than rectangular or square thrust pistons.
The thrust part of the charging element does not have
to have the same shape or the same cross section as the
guide part which, according to the invention, must have
a circular-cylindrical cross section so as to achieve
the advantages striven for.
An advantageous development of the invention proposes
that the thrust part has a diameter which differs from
the diameter of the guide part. In principle, however,
it may also be advantageous for the thrust part to have
a cross section which differs from the circular-
cylindrical cross section. If the thrust part has a
smaller diameter than the guide part or a cross section
which differs from the circular-cylindrical cross
section, for example a rectangular cross section,
separate measures must then be taken, for example in
the form of scrapers, in order to prevent the
combustible material being displaced behind the thrust
part. If, on the other hand, the circular-cylindrical
cross section of the thrust part is smaller than that
of the guide part, the thrust part can then also extend
through a first of a number of sealing arrangements for
the guide part, so that a smaller space requirement can
be achieved outside the feed device in the direction of
movement of the charging element.
It can also prove advantageous if , in a development of
the invention, the thrust part has a surface structure
which differs from that of the guide part. Such a
different surface structure can be achieved by
machining or by means of a different material. To
achieve particularly good sealing, it may be necessary
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to provide the guide part with a higher surface quality
which is not necessary for the heavy duty of the thrust
part which comes into contact with the combustible
material to be fed.
An advantageous development of the invention consists
in that the guide arrangement for the guide part
comprises two sets of in each case three guide rollers,
which sets are arranged at a distance from one another,
at least one of these three guide rollers being
adjustable radially in relation to the guide part.
An alternative advantageous embodiment of the charging
device consists in that the guide arrangement for the
guide part comprises at least one pair of rollers lying
opposite one another, which are mounted rotatably on
the guide part and are guided in profiled rails . These
profiled rails are provided outside the sealing
arrangement and receive at least one pair, preferably
two pairs, of guide rollers lying opposite one another,
the axes of rotation of which are arranged
perpendicularly to the axis of the thrust piston and
which preferably run in U-shaped guide rails.
These guide arrangements are constructionally simple
and practically insusceptible to faults because even
soiling affects the guide arrangement only slightly.
An especially advantageous embodiment of the invention
consists in that the charging element is designed as a
hollow piston and is guided with its piston skirt in a
guide cylinder serving as the guide arrangement, which
is fastened, by its front end in the conveying
direction of the hollow piston, to that delimiting wall
of the charging device facing away from the combustion
or gasification chamber, and is arranged outside said
wall. Such a charging element is simple to produce
because drawn tubes can form the starting point for the
production of the charging element, which greatly
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simplifies the production of such a charging element.
In such a charging element, it is advantageous if the
guide arrangement comprises two plain bearing bushes
arranged at a distance from one another in the guide
cylinder.
The embodiment of the charging element as a hollow
piston is also a prerequisite for another advantageous
embodiment of the invention which consists in that a
driver tube is inserted inside the hollow charging
element and is, at the piston foot, connected
detachably to the charging element, on the front end,
projecting into the charging element, of which tube a
drive device for the reciprocating movement of the
charging element engages. The particular advantage is
that the point of engagement of the drive device can be
located a long way into the hollow piston so that the
space requirement at the rear end of the charging
element for the arrangement of the drive device is
reduced. The detachable connection of the driver tube
to the charging element also has the advantage that the
connection between the drive device and the driver tube
can be made before the latter is introduced into the
charging element. This has a favourable influence on
the mounting of such a charging element. The
advantageous embodiment is particularly favourable
when, according to another embodiment of the invention,
in a case where use is made of a piston/cylinder drive
unit, this is, in the retracted end position, held
virtually completely in the driver tube. As a result,
the space requirement behind the charging element is at
its smallest because the connection point between the
drive device and the charging element can be located
very close to the front end of the latter, which
without such a driver tube would lead to great mounting
problems.
When, in a further embodiment of the invention, the
thrust part of the charging element is held in an
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upwardly open guide recess of the feed table, this
ensures relief of the guide arrangement in the case of
long movement paths and, over and above this, a defined
conveying region also. It is advisable for the
conveying capacity of the charging element to be
adjustable as a function of a parameter depending on
the course of gasification or incineration. In this
way, the course and the nature of the gasification or
incineration can be influenced via adjustment of the
quantity of the combustible material to be introduced.
The invention is described in greater detail below with
reference to various exemplary embodiments.
In the drawing,
Figure 1 shows a longitudinal section through a
diagrammatically illustrated incineration
plant;
Figure 2 shows a partly sectioned side view of a
charging device with an extended charging
element;
Figure 3 shows a partial view of the illustration
according to Figure 2 in the retracted
position of the charging element;
Figure 4 shows a modified exemplary embodiment;
Figure 5 shows a section along the line V-V in Figure
4;
Figure 6 shows another modified exemplary embodiment;
Figure 7 shows a section along the line Va-Va in
Figure 6;
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Figure 8 shows a partial illustration of a front view
of a charging device according to Figure 2;
Figure 9 shows an embodiment which has been changed in
relation to Figure 8; and
Figure 10 shows a further exemplary embodiment of a
charging device.
The incineration plant illustrated in Figure 1
comprises a combustion grate 1, a charging device 2 and
a combustion chamber 3 with adjoining gas flue 4, to
which other gas flues and units downstream of the
incineration plant, in particular steam-generating and
waste-gas cleaning units, are connected, which are here
not illustrated or described in greater detail.
The combustion grate 1 comprises individual grate steps
5, each second one of which is connected to a drive
which is designated as a whole by 6 and makes it
possible to adjust the stoking rate. Provided below the
combustion grate are underblast chambers 7.1 to 7.5
which are subdivided in both the longitudinal and
transverse direction and have primary air admitted to
them separately via individual lines 8.1 to 8.5. At the
end of the combustion grate, the burnt-out ash is
discharged by means of an ash-discharging device, in
the exemplary embodiment illustrated an ash roller 9,
into an ash chute 10, from where the ash falls into an
ash-remover (not shown).
The charging device 2 comprises a feed hopper 11, a
feed chute 12, a feed table 13 and at least one
charging element 14 which pushes the refuse sliding
down in the feed chute 12 over a charging edge 13' of
the feed table 13 into the combustion chamber 3 and
onto the combustion grate 1.
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Fundamentally, a charging element 14 consists of a
thrust part 15 and a guide part 16. These can have
different shapes, as emerges from the various exemplary
embodiments.
In the exemplary embodiments illustrated in Figures 2
to 8, the charging element 14 as a whole consists of a
one-piece hollow piston, the front, thrust part of
which, which comes into contact with the combustible
material 17 to be conveyed, is designated by 15 and the
remaining guide part of which is designated by 16, and
which, even when it is in the furthest forward position
according to Figure 2, always remains in a guide
cylinder 18, in which the guide part 16 is guided by
means of plain bearings 19 and 20. 21 and 22 indicate
seals for achieving gastight sealing of the charging
element. If the thrust part 15 differs from the guide
part 16 with regard to its surface quality or surface
nature, the front seal 21 can serve primarily as a
scraper, through which the thrust part 15 extends,
while the rear seal 22, interacting with the guide part
16 which has a smoother surface, constitutes better
sealing against gases which could either escape from
the combustion chamber or could be sucked into the
combustion chamber in the form of ambient air or
secondary air.
Provided inside the charging element 14 is a driver
tube 23 which is fastened detachably to the rear end 24
of the charging element 14 and consequently to its
piston foot facing away from the combustion chamber.
Provided at the front end of the driver tube 23 is an
articulation part 25 for fastening the piston rod 26 of
a drive unit 27 which, in the retracted state of the
charging element 14, as emerges from Figure 3, is held
virtually completely in the driver tube 23. In the
pushed-forward end position according to Figure 2, the
cylinder arrangement of the drive unit 27 lies
virtually completely outside the driver tube 23. It can
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be seen from this that this driver tube makes it
possible to reduce the necessary space requirement to
the rear for the arrangement of the rear articulation
part 28 and, over and above this, the driver tube
allows the mounting of the front articulation part 25,
which in the case of direct fastening of this
articulation part to the thrust part, in a position
lying so far forward, would lead to considerable
mounting problems.
Figures 4 and 5 illustrate a modified embodiment of the
guide and sealing arrangement for the charging element
14. In this embodiment, three guide rollers 29 aligned
in the radial direction are provided, at least one of
which, in Figure 5 the top one, can be adjusted in the
direction of the double arrow 30. Provided on the rear
wall 31 of the feed chute 12, for sealing the charging
element 14, is a sealing arrangement 32 which surrounds
the guide part sealingly and is fastened to the wall.
Figures 6 and 7 show another embodiment of the guide
arrangement of the charging element 14, in which
laterally arranged axial rollers 33 are in each case
guided in a rail 34. In this case, the sealing 32
corresponds to that in Figure 4.
When the charging element as a whole is designed as a
piston of circular-cylindrical shape, it is necessary
to provide a number of such charging elements 14 next
to one another, as emerges from Figures 8 and 9. In
this case, the charging elements are held in guide
recesses 35.
Figure 10 shows an exemplary embodiment in which the
charging element consists of a thrust part 36 of
rectangular cross section and two guide parts 37 of
circular-cylindrical cross section which are held in
plain bearings 38. Sealing arrangements are indicated
by 39. The guide parts 37 can be designed as piston
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rods of hydraulic piston/cylinder arrangements (not
shown in full) in order to move the thrust part 36 of
known construction type. In order that no combustible
material can penetrate behind the thrust part 36, a
scraper 40 is provided.
The charging elements can - as illustrated - be
arranged in a horizontal position, or it is also
possible to arrange these obliquely upwards or
obliquely downwards at a certain angle.
The common underlying idea of all the embodiments is to
design the charging element in such a manner that it
comprises a thrust part and a guide part, the guide
part serving to guide the thrust part and seal the
charging element, so that gases produced in the
incineration or gasification plant cannot escape to the
outside and secondary air cannot be sucked into the
incineration plant, which can have an unfavourable
influence on the course of combustion and in particular
an unfavourable influence on a gasification process.
