Note: Descriptions are shown in the official language in which they were submitted.
CA 02816693 2013-05-01
Process for cooling hot bulk material and cooler
The invention relates to a cooler for cooling hot bulk material, in which
cooling
gas flows approximately transversely to the conveying direction through a bulk
material bed and in the process takes up the heat of the bulk material,
wherein an
apparatus which carries the bulk material bed has a ventilation floor through
which cooling gas flows, and wherein the conveying principle provides for
planks
which extend in the conveying direction, in which at least two adjacent planks
are
moved simultaneously in the conveying direction and non-simultaneously counter
to the conveying direction.
For the production of cement, raw meal consisting of lime-containing rock and
silicate-containing rock is firstly freed of chemically bound carbon dioxide
in the
form of the carbonate by a first heat treatment, and then the thus calcined
raw
meal is sintered in a rotary tubular kiln at temperatures of up to 1450 C. In
this
case, various phases of stoichiometrically different calcium silicates form in
a
solid-state reaction, and the grain size distribution of the raw meal
introduced into
the process changes because the grains of the raw meal are joined to one
another during the sintering. After they have passed through the rotary
tubular
kiln, the grains of the clinker which is thus formed generally have the size
of
coarse meal right up to fist-sized clinker granules. The crystallization in
the solid-
state reaction during sintering for forming the desired phases requires rapid
quenching of the clinker after the sintering process during passage through
the
rotary tubular kiln. The freshly sintered clinker, which forms a very abrasive
and
very hot material, is therefore discharged onto a clinker cooler. In the
clinker
cooler, heat is rapidly taken from the fresh clinker so as to quench the
clinker and
also to recycle the heat present in the clinker to the very heat-intensive
cement
production process.
CA 02816693 2013-05-01
- 2 -
The cooling of the cement clinker requires considerable procedural expenditure
because the clinker is very hot and also because the clinker has a very
abrasive
action.
Processes for cooling the cement clinker which have been known for a long time
provide for discharging the cement clinker from the rotary tubular kiln onto a
stepped grate, where the cement clinker to be cooled forms a bulk material
bed.
The stepped grate is a static grate on which a static passive layer of cement
clinker forms. This passive layer protects the static grate from overheating
and
abrasion. The clinker emerging from the rotary tubular kiln drops onto this
passive
layer and slips over the natural slope angle which forms in the conveying
direction onto a moving conveying grate. As it is transported over the stepped
grate, the cement clinker is cooled by cooling air conducted through the
conveying grate from below. The stepped grate is adjoined by a moving
conveying grate with grate bars which move alternately in the conveying
direction
and have grate plates. This conveys the clinker in the direction towards the
end of
the cooler, the cooling air flowing into the material to be cooled through the
movable grate bars and through the stationary grate bars with grate plates or
through interstices which are present between the movable grate bars with
grate
plates. This known type of clinker coolers has proved itself in practice.
However,
a disadvantage of these clinker coolers is the high wear rate, since the
abrasive
and also very hot clinker passes into the interstices between the steps. A
cooler
of this type is therefore high-maintenance compared to more modern clinker
coolers.
Other concepts for improving the cooler, disclosed in DE2831473A1, include
pulling the clinker over a stationary, ventilated surface using a traction
chain. This
type of cooler, too, is sensitive to a high degree of wear, because the
traction
chain together with the movable links thereof is worn through in the hot
cement
clinker.
CA 02816693 2013-05-01
- 3 -
Yet another concept, which is disclosed in EP1373818B1, pursues the forward
movement of a plane which occupies the entire cooler in a first phase, the
lowering of a blocking plate in the vicinity of the rotary tubular kiln at the
start of
the clinker cooler in a second phase, and the withdrawal of the entire plane
counter to the blocking action of the blocking plate, such that, when the
plane is
withdrawn, the cooler is pushed forwards with respect to the latter. This type
of
cooler has the advantage that no machine parts which move in relation to one
another are in direct contact with the hot, abrasive clinker. In the case of
this type
of cooler, however, very high forces have to be applied to move the plane
counter
to the action of the blocking plate, and the bulk material bed tends to
accumulate
on the blocking plate, and therefore it is not always possible to achieve
uniform
transport with a uniform and reproducible bulk material bed height and
therefore
reproducible properties of the clinker cooling. This document, mentioned here,
also discloses that it would be advantageous to move the plane so slowly that
the
bulk material bed does not carry out any vertical mixing movement. The
abrasion
would thereby be reduced.
The article "Sind KOhlroste KlinkerkOhler oder Warmerekuperatoren?" ["Are
cooling grates clinker coolers or heat recuperators?"] from the journal
entitled
Zement-Kalk-Gips, 37th Volume, No. 5/1984 explains theoretical considerations
of clinker cooling. This article focuses on a cross-flow model, which states
that
the clinker flows in the transport direction and in the process cooling air
flows
through it perpendicularly to the transport direction. The consideration on
which
the article is based is that in this case a wedge of a thermal zone which lies
in the
bulk material bed is formed, the wide part of the wedge being arranged at the
start of the cooler and the flat part of the wedge being arranged at the end
of the
cooler. This thermal wedge forms, according to the established concept,
because
the cooling air penetrates the hot clinker from the bottom upwards. If the
entire
layer thickness of the clinker is still hot, the cooling air which enters the
clinker
from below is heated even after a short distance through the clinker layer, in
which case the lower clinker layer is left cooled and the upper, significantly
wider
CA 02816693 2013-05-01
- 4 -
part of the layer of the bulk material bed is still hot. Since the clinker
continues to
move along, this process takes place again in the conveying direction. Here,
the
cold cooling air penetrates the already cold layer of the bulk material bed
and
then the still hot lower layer, which is cooled, and therefore the width of
the hot
layer is reduced. This process takes place until the entire layer thickness of
the
layer of the bulk material bed of the clinker is cooled. The desired effect of
this
gradual cooling is for the cooling air to leave the uppermost layer of the
bulk
material bed at the highest possible temperature. As a result, the clinker is
cooled
with little cooling air being used, and first and foremost the heat is
transported
back into the process at a high temperature. According to established
concepts, a
bulk material bed with little mixing movement, primarily little mixing
movement
from the bottom upwards, is therefore advantageous. This is because the
established cross-flow cooler theory also states that a greatly moving bulk
material bed could have the effect that an already cooled grain might pass
into
the still hot region and be heated again by the still hot layer. As a result,
the
temperature of the uppermost layer would be reduced, because the thermal
energy is distributed over a greater volume of the bulk material to be cooled.
As a
consequence, the cooling air temperature upon discharge from the clinker
cooler
layer would be reduced, and the efficiency of the cooling would therefore
likewise
be reduced.
This consideration led to the development of a further type of cooler, which
is
mentioned in the Danish patent application DK 140399. In this type of cooler,
the
floor of the cooler, which consists of planks extending in the conveying
direction,
is moved in its entirety in the conveying direction in a first phase, and then
in
further phases the individual planks are withdrawn individually under the bulk
material to be cooled counter to the conveying direction. Since the bulk
material
bed lies on the other, stationary planks, the bulk material bed is held over
the
plank which moves back. Cooling air is blown through the moving planks such
that the desired cooling effect is achieved. First experiences with this type
of
cooler showed that the bulk material bed is loosened over the borderlines
CA 02816693 2013-05-01
- 5 -
between two planks when the planks move in relation to one another. Channels
with little flow resistance form as a result, such that cooling air flows with
preference through these loosened borderline areas without cooling the bulk
material to be cooled. This means that the recuperation efficiency of the
cooler is
thereby reduced, and the temperature of the air leaving the bulk material bed
to
be cooled is likewise reduced by the air flowing without a cooling effect
through
the bulk material bed. DK 140399 therefore proposes fitting flow obstacles on
the
moving planks, as a result of which the planks are divided into individual
portions.
The concept according to DK 140399 is that the bulk material bed rolls over
the
flow obstacles when the individual planks are withdrawn individually, such
that
the loosened areas over the borderlines between the planks, which are denoted
as cold channels, close.
Further experiences with this type of cooler have shown that, in the teaching
according to DK 140399, those portions between the flow obstacles which travel
to and fro with the plank fill with a clinker layer. The effect which arises
according
to this conveying principle appears firstly in a bulk material bed height
level with
the upper limit of the flow obstacles. A type of autogenous wear protection is
thereby formed on the planks of this type of cooler. Although this is
advantageous
for the use of this type of cooler, because the individual parts of this type
of cooler
do not come into contact with the closing, hot clinker layer, the formation of
cold
channels is not desirably reduced as a result.
A further configuration of this type of cooler is disclosed in EP1509737B1. In
said
document, it is emphasized that the cooler should be operated in such a way
that
no vertical mixing is carried out in the bulk material bed, and the height of
the
clinker bed should be a specific height in relation to the width of the
individual
planks. It is thereby expected that the transport efficiency and also the
efficiency
of the heat recovery would be positively influenced as a result.
In addition to the last-mentioned types of cooler, further types of a clinker
cooler
have been developed and, as so-called crossbar coolers, have been used in
CA 02816693 2013-05-01
- 6 -
clinker cooling technology. In these types of coolers, individual drivers
which
protrude from a supporting grate through which cooling air flows are moved
forwards and backwards. This type of cooler is described, for example, in
EP127280362. This type of cooler typically has wedge-shaped drivers which
point in the transport direction with their virtually perpendicular side and
point
counter to the transport direction with their flattened wedge side. The
transport
mechanism involves applying the above-described principle of common forward
movement in the transport direction and of individual backward movement. The
wedge form is said to have the effect that the bulk material bed moves over
the
driver during the backward movement of the individual drivers, which move in
relation to the ventilated supporting grate, and by contrast is pushed by the
virtually perpendicular side in the conveying direction upon movement in the
conveying direction.
In spite of the mixing of the bulk material bed which is produced by the
drivers
that move in relation to the supporting grate and plough through the bulk
material
bed, satisfactory recuperation rates are achieved with these types of cooler.
A
disadvantage of this type of cooler is the high degree of wear to which the
drivers
are subjected.
It is an object of the invention to provide a cooler which combines the
advantages
of the known types of cooler and in which the disadvantages of the known types
of cooler are avoided.
The object according to the invention is achieved in that the planks have
differently configured surfaces, on which the bulk material bed lies, in the
conveying direction, and these surfaces, on account of their different
frictional
locking with the bulk material bed lying thereon, lead to mean transport
speeds
which differ from one another, such that as a result the bulk material bed is
stretched in the region of quicker conveying and compressed in the region of
slower conveying. Further advantageous configurations of the invention are
given
- 7 -
herein below.
According to the invention, use is made of a conveying principle in which at
least two
adjacent planks are moved simultaneously in the conveying direction and non-
simultaneously counter to the conveying direction. The disadvantage of this
conveying
principle, specifically the undesirable loosening of the bulk material bed
over the
borderline extending in the conveying direction between the planks that move
in relation
to one another in and counter to the conveying direction, is avoided by virtue
of the fact
that, given alternative stretching and compression of the layer of the bulk
material bed,
this loosened area is closed during stretching by bulk material which
continues to flow
from the side, and is closed during compression by compaction of the bulk
material. In
contrast to the introduction of simple flow obstacles, which leads not to a
movement like
a transverse wave but to the formation of a layer of the bulk material bed
which moves
together with the planks, this concomitantly moving layer cannot form at all
according to
the invention, and nevertheless the formation of cold channels is prevented.
The
invention has yet another advantage. Like a tumbling movement, the continuous,
alternating stretching and compression leads to considerable vertical mixing
of the bulk
material bed, without the presence of flow obstacles which protrude into the
bulk
material bed. Although the established concept states that it is specifically
the absence
of a vertical mixing movement which leads to a particularly good recuperation
rate,
because the above-described thermal wedge forms as a result, it has
surprisingly been
found that the temperature of the spent air produced by the cooler according
to the
invention and the corresponding process is hotter than is the case in the
prior art
without differently formed surfaces. A further surprising effect is that the
clinker grains
and granules leaving the cooler, particularly relatively large clinker pieces,
still have
glowing regions much less often. In the case of conventional coolers, it can
be observed
specifically that, in a typical concentration, the bulk material leaving the
cooler, which is
generally comminuted by a crusher, has individual clinker pieces which
CA 2816693 2019-02-15
CA 02816693 2013-05-01
- 8 -
still glow red. If the conveyor belt which is arranged at the crusher at the
end of
the cooler and conveys the freshly crushed clinker into a silo is observed,
individual clinker pieces which still glow red are apparent depending on the
quality of the clinker cooler. These undesirably carry a large amount of heat
along
into the clinker silo, which is not recuperated and unnecessarily burdens the
silo
with heat.
Within the context of the present invention, it is assumed that the
established
model of cross-flow cooling suitably describes the conditions in the layer of
the
bulk material bed when the bulk material bed has an ideal form. This means
that
it behaves like a fluidized bulk material bed which is nevertheless free of
mixing
movement. This is because the cooling air flowing through the bulk material
bed
can then cool each particle completely and from all sides. However, the
sintered
clinker has material properties in terms of thermal conduction like some
ceramics,
in which a glowing region can be present in the immediate vicinity of a very
much
colder region. It is therefore possible for a fist-sized clinker piece to
still glow on
one side and to have a temperature of 60 C to 80 C on an opposite side. It is
also possible for hot granule cores, which are exposed only during crushing,
to
survive within relatively large clinker pieces. It is assumed that these hot
spots
can form on the clinker granules when the clinker granules partially lie in
the
slipstream of adjacent clinker grains on account of the fact that no mixing
movement occurs. Although the established cross-flow cooling theory assumes
that a mixing movement leads to relatively poor heat recuperation, it is
suspected
that it is precisely the mixing movement which causes better recuperation,
because slipstreams resulting from the movement of the bulk material bed are
avoided by active mixing upon alternative stretching and compression of the
bulk
material bed.
A simple configuration of the invention provides that the planks of the
clinker
cooler have an apparatus which carries the bulk material bed and has a
ventilation floor, the plank having differently configured surfaces in the
conveying
direction. The surface which differs from the supporting grates as the
apparatus
CA 02816693 2013-05-01
- 9 -
carrying the bulk material bed is a simple smooth surface with a very small
degree of frictional locking. During the common forward movement, it is not
apparent that the different frictional locking of the surfaces comes into
effect, but
during the return movement the different surface configuration makes its
presence felt in the length of the planks in the conveying direction. In an
ideal
concept, the bulk material bed is held in the region in which a plank moves
back
individually under the bulk material bed by the adjacent strip of bulk
material,
which lies on a plank which at that time does not move, such that, despite a
return movement of the plank, the strip of the bulk material bed lying thereon
remains in its position. During actual operation, however, it becomes apparent
that the regions over the borderlines between the planks are loosened, which
can
be attributed to the fact that the strip of the bulk material bed is withdrawn
over
the plank moving back with a specific, non-negligible force, as a result of
which
the loosening is created. In regions of the plank in which the frictional
locking is
very low, the loosening is therefore less pronounced, and in those regions in
which a supporting grate is present as the surface carrying the bulk material
bed,
the loosening is highly pronounced. As a result, the strip of the bulk
material bed
is compressed at those points with low frictional locking by the restoring
force of
the strips of the bulk material bed. A similar situation arises if a plank
part having
a surface with low frictional locking is adjacent to a plank part with high
frictional
locking and the adjacent part moves back. On account of the high friction of
the
strips of the bulk material bed over the individual planks, the strip of the
bulk
material bed over the plank moving back pulls the strip part of the bulk
material
bed over the surface with low frictional locking to the rear, where it
compacts the
bulk material in the rear part and loosens the bulk material in the part
directed
forwards. Compaction and loosening therefore takes place in each phase of the
cooler movement, as a result of which a tumbling movement with vertical mixing
and closure of the cold channels arises over the borderlines between the
planks
which move in relation to one another.
CA 02816693 2013-05-01
1 0 -
The first surfaces with particularly low frictional locking are faced by those
second
surfaces which preferably have overlapping profiles as the supporting grate,
between which the cooling gas flows into the bulk material bed.
In a particular configuration of the invention, it is provided that one
configuration
of the surfaces has a wedge form, the flat end of which is oriented counter to
the
conveying direction. In contrast to the crossbar coolers, in which the wedges
move in relation to the surface of the supporting grate and therefore
represent
pushing elements, it is provided here that the wedges are located permanently
on
the moving supporting grate. As a result of the nature of the forward movement
described, the bulk material has to move over the wedge and drops down from
the virtually perpendicular side of the wedge at the end of the wedge in the
conveying direction. In this case, both the closure of the cold channels and
the
vertical mixing are further promoted. In contrast to the teaching according to
DK
140399, in this case provision is made of wedges with particularly low
frictional
locking, rather than simple flow obstacles. As a result, an elevated,
autogenous
wear-resistant layer does not form between the wedges, as is the case in the
case of the flow obstacles according to DK 140399, and the wedges bring about
the closure of the cold channels in addition to the vertical circulation.
Yet another variant of the invention, which reinforces the circulation
effects,
provides that one configuration of the surfaces has a wedge form which is
inclined to the side and the flat end of which is oriented counter to the
conveying
direction. This surface configuration has a structure like a plough, which
lies on its
back and the ploughshare of which points upwards. In the event of a rearward
movement, the wedges inclined to the side slide under the bulk material bed
which compresses at this point in this phase, the latter slipping to the
sloping side
of the cooler. The part of the bulk material bed which lies to the sloping
side is
thereby compressed, the borderline is filled in and the bulk material bed
undergoes a rotational movement about an axis extending in the conveying
direction. The bulk material bed moves like a helix from the rotary tubular
kiln to
the end of the cooler, one helix being present per plank. This embodiment
CA 02816693 2013-05-01
-. 1 1 -
indicated last here leads to a very intense tumbling movement and vertical
mixing, admittedly at the cost of an increased transport resistance, which has
to
be introduced into the bulk material bed with a higher hydraulic force. The
disadvantage of the increased use of hydraulic energy in terms of cost is more
than compensated for by the improved heat recuperation.
In order to also improve the closing action for the plough and the
borderlines, it is
provided to arrange the different surfaces in regularly repetitive patterns on
the
bulk material transport surface of the cooler. A pattern which has improved
the
closing effect for the plough and the borderlines is a pattern of lines
arranged
obliquely to the conveying direction. In a first case, these can all be
aligned, as a
result of which it is possible to compensate for a unilateral discharge
behaviour of
the rotary tubular kiln. Rotary tubular kilns tend to separate clinker grain
fractions
of different sizes, the fine clinker grains and the coarse clinker grains
being
discharged alongside one another. Other rotary tubular kilns in turn do not
discharge the burnt clinker centrally, but with lateral displacement.
In order to strengthen the plough action without producing a net transport of
the
bulk material bed to one or the other side of the clinker cooler, it is
provided that
the direction of the lines, which are bent with respect to the conveying
direction,
of the arrangement of the surfaces with low frictional locking alternates,
i.e. they
point to the left and then to the right.
In a particular configuration of the invention, it is provided that the
arrangement of
the surfaces with low frictional locking has an arch form, the arch being
oriented
symmetrically with respect to the conveying direction. The effect of this arch
form
is to compact the bed in the direction of the centre of the clinker cooler,
depending on the selection of the surface form of the surface with low
frictional
locking. If the surface which is planar in the transport plane of the clinker
cooler is
selected, the tumbling movement continues in arch form. If, by contrast, the
wedge form which slopes to the side is used, the conveying action towards the
CA 02816693 2013-05-01
- 1 2 -
centre is strengthened or weakened, depending on the lateral orientation of
the
wedge form.
In a very particular configuration, the surfaces can also be mixed. If, by way
of
example, the wedge-shaped, smooth surfaces are used on the sides and the
planar surfaces with smooth frictional locking are used in the centre line of
the
conveying direction, the transport efficiency is different between the side
wall and
the centre line given the same stroke and the same stroke frequency of the
individual planks, and the different transport efficiency can be utilized in
order to
compensate for a non-uniform discharge behaviour of the rotary tubular kiln.
The invention is explained in more detail with reference to the following
figures:
Figure 1 shows a cooler according to the invention in a first configuration
with
planar surfaces with low frictional locking,
Figure 2 is an enlarged detail showing the planar surface parts,
Figure 3 shows different layouts for the different surfaces,
Figure 4 shows a further configuration of the cooler with wedge-shaped
surface parts with low frictional locking,
Figure 5.1 is an enlarged detail showing the wedge-shaped surface parts,
Figure 5.2 is a side view showing the wedge-shaped surface parts in the cooler
transport plane,
Figure 6 shows a third configuration of the cooler with wedge-shaped
surface
parts which slope to the side,
Figure 7 is a view from the front showing the wedge-shaped surface parts
which slope to the side in the cooler transport plane.
Figure 1 shows the parts of a clinker cooler 100 which are essential to the
invention in a first configuration. Said clinker cooler consists of four
planks 101,
102, 103 and 104, which are arranged alongside one another and extend in the
CA 02816693 2013-05-01
- 13 -
conveying direction 105. The transverse side shown in the foreground is that
side
onto which the rotary tubular kiln discharges the clinker, and the transverse
side
shown in the background of the figure forms the end of the cooler. To cool the
clinker, the clinker is discharged onto the front side of the clinker cooler
100, and
in the process cooling air 107 flows through it, said cooling air flowing from
below
through the cassette-shaped inserts 110 into the bulk material bed (which is
not
shown here) lying on the cooler 100. The cassette-shaped inserts have
overlapping profiles through which the cooling air 107 flows but through which
the
clinker cannot drop from above. Smooth surface structures with second inserts
115 alternate with the cassette-shaped inserts 110. These inserts 115 can also
be provided with cooling air openings. It is important that the frictional
locking of
the surfaces of the second inserts 115 having a smooth surface differs
considerably from the frictional locking of the cassette-shaped inserts 110,
since
it is only as a result of the different frictional locking along the transport
surface of
the cooler 100 that the compacting and re-loosening action described above
takes effect, as a result of which a tumbling movement of the bulk material
bed is
produced, which leads to vertical mixing and which regularly closes the
borderlines over the planks arranged alongside one another when said
borderlines are torn open when two planks 101, 102, 103 and 104 move in
relation to one another.
The inserts 115 with low frictional locking are shown in the enlarged detail
in
Figure 2. These replace the cassette-shaped inserts 110 at regular intervals,
such that an alternatively compacting and re-loosening action is established
at
those points in the strip of the bulk material bed over the planks 101, 102,
103
and 104 where the second inserts 115 are arranged.
In addition to the form of the surface configuration of the inserts 115, the
arrangement thereof in the cooler transport plane is also the cause of the
different
surface configurations. The simplest type of arrangement, as shown in
Subfigure
3a, is a regular alternation of cassette-shaped inserts 110 having overlapping
profiles, which are laid slightly deeper in order to form a depression for an
CA 02816693 2013-05-01
- 1 4 -
autogenous wear-resistant layer in the recess, and second inserts having a
virtually planar surface. This arrangement leads to an almost peristaltic
tumbling
movement of the bulk material in the strips of the bulk material bed which lie
over
the individual planks 101, 102, 103 and 104.
In addition to the regular alternation over the entire width of the cooler, it
is also
possible to arrange the second surfaces 115 with low frictional locking
obliquely
with respect to the cooler transport direction 105, as shown in Subfigure 3b.
In
order to avoid a net conveying effect to the side of the cooler, it is
possible to
regularly alternate the oblique arrangement, such that the tumbling movement
acts to one side and then to the other side of the cooler 100.
Subfigure 3c, finally, shows an arrangement showing a net conveying effect to
the side if the tumbling movement is not distributed symmetrically, as shown
in
Subfigure 3a, but rather dissymmetrically over the cooler transport surface.
Subfigure 3d, finally, shows an arch-shaped arrangement of the second surfaces
115, the arches being arranged symmetrically about the centre line of the
conveying direction 105.
Figure 4 shows a configuration of the cooler according to the invention as a
cooler 200, which likewise has four planks 201, 202, 203 and 204 which lie
alongside one another and extend in the conveying direction 205, in this case
the
cooling air penetrating from below not being shown for simplification. In
contrast
to the cooler shown in Figure 1, the second surfaces 215 in this cooler have a
wedge-shaped configuration, are arranged fixedly on the planks 201, 202, 203
and 204 and do not move as in the case of a cooler type which appears to be
extremely similar, in which the wedge-shaped pushing elements move in relation
to the plank surface. In the arrangement shown here, the virtually
perpendicular
surfaces 216 point in the conveying direction 205 and the flat ends of the
wedges
217 point counter to the conveying direction. Upon common forward movement,
the action of the perpendicular surfaces 216 does not have an effect, because
the
entire bulk material bed moves forwards on the cooler 200. When individual
CA 02816693 2013-05-01
- 15 -
planks 201, 202, 203 or 204 are withdrawn, the second, wedge-shaped inserts
215 slide under the strip of the bulk material bed located over the plank
moving
counter to the conveying direction 205, and in the process lift the strip of
the bulk
material bed over themselves, and the bulk material bed drops over the
virtually
perpendicular edge 216, the bulk material bed being newly compacted and in the
process also undergoing vertical mixing. In contrast to the flow obstacles
according to DK 140399, in this case the bed is gently lifted by a wedge with
low
frictional locking and circulated, with no depression being formed between the
individual wedges which is filled with a layer of the bulk material bed
stationary
over the planks.
The arrangement of the wedge-shaped inserts 215 in the cooler 200 which is
otherwise equipped with cassette-shaped inserts 110 provided with overlapping
profiled elements is shown in an enlarged detail in Figure 5.1, which shows
the
arrangement of the virtually perpendicular side over which the bulk material
emerges when the individual planks 201, 202, 203 and 204 are withdrawn.
Figure 5.2, finally, is a sketched side view showing the cooler transport
plane of
the cooler 200, the wedge-shaped inserts 215 protruding slightly over the
cooler
transport plane.
Figure 6, finally, shows a third configuration of the cooler as a cooler 300,
in this
case too the cooling air penetrating from below not being shown for
simplification
compared with the illustration in Figure 1. In this configuration, the second
inserts
315 of the cooler, which is otherwise identical to coolers 100 and 200, are in
the
form of wedges which slope to one side. When individual planks 301, 302, 303
or
304 are withdrawn, the second insert 315 with low frictional locking compared
to
the cassette-shaped inserts 110 slides under the bulk material bed, which is
compacted to the sloping side and then drops over the edge of the second
insert
315 which points in the conveying direction. When the second insert 315 is
pulled
through the bulk material bed, this creates a shovel plough-like action, as a
result
of which the bulk material is moved like a helix in the conveying direction,
and in
CA 02816693 2013-05-01
- 16 -
the process undergoes considerable vertical mixing. The mixing always exposes
those parts of the surface of the clinker with poor thermal conductivity which
still
contain surface heat. As a result, this heat can be recuperated and the
overall
efficiency of the clinker cooler increases.
It is possible to alternate the rotational movement of the clinker in the
strip of the
bulk material bed over a respective plank 301, 302, 303 and 304, in order to
thereby prevent a net conveying action to the side, and it is also possible to
keep
the rotational movement uniform by identical orientation of the wedges to the
side, in order to thereby obtain desired net conveying to the side.
The concept of the invention relates to a deliberate disruption of the moving
floor
conveyor known per se, in order firstly to be able to avoid fluidization of
the bulk
material bed but also nevertheless to avoid the situation where hot, non-
fluidized
clinker granules are in the slipstream of others and therefore cannot emit
their
heat. In order to achieve this, it is possible to select the planar or the
wedge-
shaped surface parts or the wedge-shaped surface parts with an orientation
which slopes to the side as surface parts, and to arrange these in different
layout
patterns in the cooler transport plane. In this way, the advantages of some
types
of cooler, such as for example the recuperation efficiency, are retained and
other
disadvantages, such as moving elements in the hot layer of the bulk material
bed,
are not present. Loosened areas which are inherent to the transport system
over
the borderline between the individual strips of the bulk material bed, and
which
arise in particular in the case of small bulk material bed heights, are closed
or the
formation thereof is suppressed.
CA 02816693 2013-05-01
- 17 -
LIST OF REFERENCE SYMBOLS
100 Clinker cooler 204 Plank
101 Plank 205 Conveying direction
102 Plank 215 Wedge-shaped insert with
103 Plank low frictional locking
104 Plank 300 Clinker cooler
105 Conveying direction 301 Plank
107 Cooling air 302 Plank
110 Insert 303 Plank
115 Insert with low frictional locking 304 Plank
200 Clinker cooler 305 Conveying direction
201 Plank 315 Wedge-shaped insert with
202 Plank low frictional locking with
203 Plank a plank sloping to the side
