Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND APPARATUS IN PNEUMATIC MATERIAL CONVEYING
SYSTEM
Background of invention
The invention relates to a method according to the preamble of claim 1.
The invention also relates to an apparatus according to claim 16.
The invention relates generally to pneumatic conveying systems, such as vacuum
conveying systems, particularly to collecting and conveying waste, such as
conveying household waste.
Systems are known in which waste is conveyed in a piping by means of suction.
In
these, waste is conveyed for long distances in the piping by suction.
Apparatuses
are utilised, inter alia, for conveying waste in different institutions.
Typical for them
is that a vacuum apparatus is used for achieving a pressure difference, in
which
apparatus underpressure in the conveying pipe is provided with vacuum
generators, such as vacuum pumps or an ejector apparatus. In the conveying
pipe, there is typically at least one valve element by opening and closing of
which
make-up air coming in the conveying pipe is regulated. The vacuum conveying
systems typically contain, inter alia, the following problems: high energy
consumption, high air flow in the piping, problems with noise, dust and fine
particles in the outlet pipe. Furthermore, prior-art apparatuses can have
moisture
problems. In rainy weather, the prior-art apparatuses can suck even e.g. 1,000
litres of water per suction from outdoor air. This causes problems with
corrosion
and blockages. For example, waste paper or equivalent sticks to the piping
when
moist. Furthermore, large systems have required arranging several separate
make-up air valves, which increases the complexity and costs of the systems.
An object of this invention is to achieve a totally novel arrangement into
connection
with material conveying systems by means of which the disadvantages of known
arrangements are avoided. A second object of the invention is to provide an
arrangement applicable for vacuum conveying systems by means of which the
noise problems of material feed can be decreased. A third object of the
invention
is to decrease the production of moisture in the piping. An additional object
of the
invention is to provide an arrangement by means of which the number of make-up
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air valves required in the system can be minimised. A further object is to
provide
an arrangement by means of which the volume of outlet air of the system and,
at
the same time, emissions of dust and fine particles and possible odour
nuisances
can be decreased.
Brief description of invention
The invention is based on an idea in which at least a part of the material
conveying
pipe belongs to a circuit in which conveying air can be circulated.
The method according to the invention is mainly characterised in that at least
a
part of the conveying piping is connectable as a section of a circuit in which
conveying air is circulated at least during the conveyance of the material
with a
pump device the suction side of which is connected to at least one separator
device and further to the conveying pipe on its return side so that at least
part of
conveying air on the pressure side of the pump is led in the circuit on the
supply
side of the conveying pipe via an ejector device.
In addition, the method according to the invention is characterised by what is
stated in claims 2-15.
The apparatus according to the invention is mainly characterised in that the
apparatus comprises a circuit which comprises at least a part of the conveying
piping, in which circuit conveying air is circulatable, and means which are
arranged
to circulate conveying air at least during the conveyance of the material with
a
pump device the suction side of which is connected to at least one separator
device and further to the conveying pipe on its return side so that at least
part of
conveying air on the pressure side of the pump is led in the circuit on the
supply
side of the conveying pipe and that the apparatus comprises an ejector device
which is arranged in the circuit on the blowing side of the pump device
between
the pump device and the conveying pipe.
The apparatus according to the invention is further characterised by what is
stated
in claims 17-28.
The arrangement according to the invention has numerous significant
advantages.
By arranging the piping of the system to comprise a circuit where at least
part of
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conveying air circulates, the volume of outlet air can be decreased. At the
same
time, the energy consumption of the system is minimised. By arranging an
ejector
device on the blowing side of the pump device of conveying air, the actuating
medium of which is outlet air of the pump device, an extremely effective
blowing
effect is provided in the circuit. By maintaining underpressure and
simultaneously
blowing, it is possible to provide an effective circulation of conveying air
in the
circuit and conveyance of material in the conveying pipe. With the arrangement
according to the invention, it is possible to decrease the volume of outlet
air
substantially and simultaneously to decrease possible problems with dust and
fine
particles in the outlet pipe. The arrangement according to the invention also
substantially decreases the noise problem caused by prior art. Moisture
accumulated in the piping is minimised and the piping can be dried by
circulating
air in the piping. As the volume of air being sucked inside decreases, also
energy
consumption decreases. By opening and closing the feed points of the system
according to the invention, the material is provided with an effective
transfer into
and conveyance in the conveying pipe when, at the same time, the noise effect
caused by the operation of the system can be minimised. By arranging the
conveying pipe of the material conveying system to consist of operating areas
i.e.
partial circuits, it is possible to effectively arrange the conveyance of the
material
in the conveying piping and emptying the feed points into the conveying pipe.
By
arranging the conveying air circulation in the reverse direction, an effective
removal of blockings is provided. In a circular piping, it is easily possible
to arrange
the change of the conveying air circulation in the reverse direction.
Brief description of figures
In the following, the invention will be described in detail by means of an
example
with reference to the accompanying drawings in which
Fig. 1 schematically shows a system according to an embodiment of the
invention,
Fig. 1 a shows a part of a system according to the invention as simplified,
Fig. 2 schematically shows a system according to an embodiment of the
invention
in a second operating mode,
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Fig. 3 schematically shows a system according to an embodiment of the
invention
in a third operating mode,
Fig. 4 schematically shows a system according to an embodiment of the
invention
in a fourth operating mode, and
Fig. 5 schematically shows a system according to an embodiment of the
invention
in a yet further operating mode.
Detailed description of invention
Fig. 1 shows a pneumatic material conveying system according to an embodiment
of the invention, particularly a waste conveying system, as a simplified
schematic
diagram. The figure shows a material conveying pipe 100 along which is
arranged
at least one, typically several feed points 61. The feed point 61 is a feed
station of
material, particularly of waste material, intended to be conveyed, from which
point
the material, particularly waste material, such as household waste, intended
to be
conveyed is fed to the conveying system. The system can comprise several feed
stations 61 from which the material intended to be conveyed is fed to a
conveying
piping 100, 100A, 1006, 1000, 100D, 100E. The feed station 61 is designated in
the figure with a point, whereby by opening and closing a gate element in
connection with the feed station, such as a valve element 60, material can be
conveyed from the feed point 61 to the conveying pipe 100. Fig. 1 a shows a
feed
point 61 used in the system according to the invention and its outlet valve 60
in
more detail. The feed point is connected on the side of the valve to the
conveying
pipe 100 or a pipe being in connection with it. Typically, the conveying
piping
comprises a main conveying pipe 100 into which several branch conveying pipes
can have been connected and into which again several feed stations 61 can have
been connected. The fed material is conveyed along the conveying piping 100,
100A, 1006, 1000, 100D to a separator device 20 in which the material being
conveyed is separated, e.g. due to dropping rate and centrifugal force, from
conveying air. The separated material is removed, e.g. when required, from the
separator device 20 to a material container, such as a waste container 51, or
to
further treatment. The material container can comprise, as in the embodiment
of
the figures, a waste compactor 50, with which the material is compacted by
compressing into smaller size, and from which the material is further conveyed
to
the waste container 51. In the embodiment of Fig. 1, the separator device 20
is
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provided with material outlet elements 21, 24. From the separating device 20,
a
conveying air channel 105 leads to means 3 for generating underpressure in the
conveying pipe. In the embodiment of Fig. 1, the means for generating
underpressure comprise a pump device 3, such as a vacuum pump unit. With the
5 means for generating underpressure, underpressure required for conveying the
material is provided in the conveying piping 100 and/or its section. The
vacuum
pump unit 3 comprises a vacuum pump 30 which is operated by an actuator 31.
The system comprises means for circulating conveying air in the circuit, a
section
of which is formed by at least a part of the conveying piping 100, 100A, 1006,
1000, 100D, 100D, 100E. In the embodiment of Fig. 1, the conveying piping 100
is
dividable into operating areas or partial circuits 100A, 1006, 1000, 100D,
100E by
valve elements VB, Vc, VD i.e. area valves.
Fig. 1 shows a situation in which the valve element VD is closed, whereby
conveying air is not able to circulate in the circuit. The suction side of the
vacuum
generator 3 being connected directly or by means of the conveying air channel
105 to at least one separator device 20, 20' in which again the delivery end
of the
conveying pipe 100 is connected, underpressure is provided in the conveying
pipe
to at least the section of the circuit which is in the material conveying
direction
between at least one valve, in Fig. 1 the valve VD, and the separator device
20.
The conveying direction of material and the travel direction of air are
designated
with arrows in Fig. 1. Underpressure prevails also in the section of the
circuit
between the separator device 20 and the vacuum generator 3, i.e. in the
conveying air channel 105, in the embodiment of the figure also in the second
separator device 20' i.e. a dust separator and the section of the conveying
air
channel 105 extending from it to the vacuum generator 3. In a case according
to
the figure, when opening in the feed point 61 its valve element 60, a material
portion intended to be conveyed is conveyed to the conveying pipe 100, in the
figure to the section 100D of the conveying pipe, to be conveyed further to
the
separator device 20. Possible make-up air in the conveying pipe comes e.g. via
the feed point 61 when opening the valve 60 in the conveying pipe.
The blowing side of the vacuum pump 30 of the pump device 3 in the embodiment
of Fig. 1 is arranged to blow in an ejector device 9 in the operating mode in
question. The ejector device 9 is arranged between the pump device 3 and the
conveying piping 100 so that an ejector nozzle 91 of the ejector device 9 is
connected to the channel 110 coming from the blowing side of the pump device.
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Then, as the actuating medium of the ejector 9 operates conveying medium,
typically air, of the blowing side of the pump device 3, such as a vacuum
generator. The ejector device 9 comprises an ejector pipe 92 in which the
ejector
nozzle 91 is arranged to direct a medium spray. The ejector device comprises a
chamber space 94 in which the ejector nozzle 91 and the first end of the
ejector
pipe 92 and a fitting 93, via which is openable and closable a connection
outside
the chamber space 94, are arranged. When the ejector nozzle 91 sprays the
medium in the ejector pipe 92, suction is provided which draws extra air along
with
it via the fitting 93. A blowing side 95 of the ejector device 9 is connected
to the
conveying pipe 100 or the channel 110 leading to the conveying pipe. The
operating principles of the ejector device are considered known as such to
those
skilled in the art and they will not be examined in more detail. From the
influence
of the ejector 9, a considerable increase is provided in the main flow blown
by the
pump device 3 due to an extra air flow via the fitting 93, typically in the
range of
20-60%. With the combination of the pump device 3 and the ejector 9, an
increase
is thus provided in the conveying air flow by means of which it is possible to
effectively provide overpressure on the blowing side of the pump and/or
underpressure and/or a suction effect on the suction side of the pump device.
In
the fitting 93 is arranged a valve element 96 and a filter element 97, such as
a dust
filter. In certain cases, the fitting 93 can also operate as an outlet
channel.
From the blowing side of the ejector 9 is arranged a connection, e.g. via the
air
channel 110, to the conveying pipe 100 on its supply side. In the air channel
110
of the blowing side is arranged the valve element 122 which, when closed,
prevents a connection of the blowing side to the usual supply side of the
conveying pipe 100.
The operation of the system is controlled so that, for emptying the feed
points of a
desired operating area, at least one valve is open in the material conveying
direction in relation to the operating area of the conveying pipe 100 and on
the
supply side of the conveying air i.e. on the side of suction, whereby the
suction is
able to affect the conveying pipe of the operating area. Let us assume that,
in the
arrangement according to the figure, the feed points 61 of the conveying pipe
area
100D are to be emptied. Then, all area valves between the separator element 20
and the operating area in the conveying pipe 100 (the section 100D of the
conveying pipe in the figure) in the conveying direction are open (the valve
126 in
the figure). Then, suction provided by at least one vacuum generator 3
prevails in
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the conveying piping 100D in the operating area. At least one valve VD on the
blowing side of the conveying pipe 100 is closed, whereby only suction
prevails in
the operating area. The feed points 61 of the operating area or at least part
of
them are emptied so that the connection of the feed point 61 (I) closest to
the
delivery end in the conveying direction of the conveying pipe, i.e. in the
embodiment according to the figure closest to the separator device 20, to the
conveying pipe 100D is opened first, whereby the material is able to convey
from
the first feed point to the conveying pipe, and before the connection of the
first
feed point (I) to the conveying pipe closes, the connection of the next feed
point 61
(II) to the conveying pipe is opened. In the embodiment of the figure, this
is, when
travelling against the material conveying direction, the next feed point 61
(II)
intended to be emptied. After this, the connection of the first feed point 61
(I) is
closed to the conveying pipe. Equivalently, the connection of the third feed
point
61 (III) intended to be emptied to the conveying pipe is opened before the
connection of the second feed point 61 (II) to the conveying pipe is closed.
This
operation is repeated until all desired feed points have been emptied. In the
figure,
it has been considered emptying all the feed points 61 of the conveying pipe
area
100D, whereby their emptying sequence to the conveying pipe 100, 100D is
designated in the figure by numerals within parentheses: (I), (II), (III),
(IV), (V), (VI),
(VII), (VIII), (IX), (X), (XI), and (XII). When the passage of the last feed
point 61
(XII) intended to be emptied in the operating area to the conveying pipe 100
has
been opened, the material has conveyed to the conveying pipe 100, 100D, and
the
passage of the feed point to the conveying pipe is closed, a connection is
opened
in the conveying pipe 100D of the operating area from the blowing side by
opening
at least one valve element VD which is between the operating area and the pump
device 3 blowing to the conveying pipe 100. Then, an intensified conveying
effect
(suction and blowing together) is provided for the material being conveyed
transferred in the conveying pipe 100, 100A, 1006, 1000, 100D. The conveying
air
circulates on a route designated with arrows in the figure, whereby material
portions conveyed from the feed points to the conveying pipe convey in the
conveying piping further to the separator device 20 in which the material
being
conveyed is separated from conveying air. In the figure, the area valve VE of
the
conveying pipe 100E of the operating area is closed, whereby conveying air is
not
able to access the conveying pipe 100E of the operating area but circulates on
the
route of the conveying pipe of the area via 100A, 1006, 1000, 100D. In
connection
with the emptying of different operating areas, the material conveying route
from
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the operating area to a delivery station, such as to the separator element 20,
can
be optimised by keeping the area valves open along the desired conveying
route.
Fig. 2 shows an operating mode of a system according to the invention in which
conveying air is able to circulate in the circuit, a section of which is
formed by at
least a part of the conveying pipe 100 and in which in the embodiment of the
figure
belong the separator device 20, the conveying air channel 105, a possible
second
separator device 20' and from the blowing side of the vacuum generator the air
channel 110 on the supply side of the conveying pipe 100. The vacuum generator
3 is arranged to circulate air in the circuit and to provide a suction effect
in the
conveying pipe 100, at least its delivery end, i.e. in the conveying direction
at the
end on the side of the separator element 20. According to the embodiment of
the
figure, the vacuum generator 3 is also arranged to provide a blowing effect in
the
conveying pipe, in the figure via the air channel 110 and the ejector device
9. One
or more area valves of the conveying pipe 100, in the figure area valves VB,
VC, VD
and the valves 122 and 126, are in the open position, whereby conveying air is
able to circulate in the circuit, a section of which is formed by at least a
part of the
feed pipe 100, whereby material portions fed in the conveying pipe from one or
more feed stations 61 move towards the separator device 20. In the ejector
device, to a main flow produced by the pump device is combined an additional
flow coming from the fitting 93 which is led, due to the suction provided by
the
ejector device, from the fitting 93 to the ejector in which it is mixed with
the main
flow. Then, with the pump device together with the ejector, an extremely
effective
blowing effect is provided in the circuit on its supply side and a suction
effect on
the side of the separator element i.e. on the return side.
Fig. 3 shows an operating mode in which materials accumulated in the separator
device are emptied. In the embodiment of the figure, at least two valve
elements in
the circuit on different sides of the separator device are closed, whereby
conveying air does not circulate via the separator devices. In the embodiment
of
the figure, there are two separator devices 20, 20'. When the separator device
20,
20' has become full, the valves 126, 127 of the circuit close and control
valves 23,
23' open, whereby the actuator 24, 24' of the outlet hatch 21, 21' of the
separator
device opens the outlet hatch 21, 21' and the material accumulated in the
separator device is emptied directly or via a conveyor device 27 to the
compactor
device 50 and further to the waste container 51. In the figure, into
connection with
the second separator device 20' i.e. the dust separator is arranged the
conveyor
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device 27 which conveys material emptied from the second separator to the
compactor device 50.
The outlet hatch 21, 21' of the separator device 20, 20' is closed and the
valves
126, 127 opened.
Fig. 4 shows an operating mode of the system in which a connection to the
outlet
channel, which is in the embodiment of the figure the fitting 93 of the
ejector 9, is
closed by means of the valve 96. Then, there is a connection from the blowing
side of the pump device 3 via the air channel 110 on the supply side of the
conveying pipe 100. The pump device circulates air in the circuit a section of
which
is formed by the conveying piping. In the embodiment of the figure, there has
also
been arranged at least one fitting 107, 107' in which there is a valve 128,
128' by
opening of which extra air can be brought on the suction side of the pump
device 3
from outside the circuit. By opening the valve 128, 128', it is possible to
raise the
pressure of air in the conveying pipe if required and to provide an increased
blowing effect in the circuit. In the embodiment of the figure, the valve 128,
128' of
at least one fitting 107, 107' is open, whereby it is possible to bring extra
air on the
suction side of the pump device 3 from outside the circuit. By opening the
valve
128, 128', it is then possible to raise the pressure of air in the conveying
pipe if
required and to provide an increased conveying rate of conveying air. The
embodiment of Fig. 3 is particularly well applicable in the air flushing of
the piping.
With the embodiment of the figure, it is also possible to dry the piping. With
the
vacuum generator is then advantageously provided a greater flow rate to the
pressure side than the suction side. Air heats up when compressing, whereby
the
drying process is also intensified.
Fig. 5 shows a further embodiment of a system according to the invention in
which
there is an operating mode by which the circulation direction of conveying air
can
be reversed at least in a section of the circuit. This can be utilised e.g. in
a
possible malfunction situation in which a blockage has been formed in the
conveying piping 100, 100A, 100B, 1000, 100D, 100E. In the conveying pipe is
arranged on the supply side at a distance from the separator device 20 a valve
element 126, at the reverse side of which in relation to the separator element
is
arranged an air channel 113 in which the blowing side of the pump device 3 is
connectable. Equivalently, in the air channel 110 of the blowing side is
arranged
the valve element 122 which, when closed, prevents a connection of at least
the
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blowing side of the pump device 3 to the usual supply side of the conveying
pipe
100. From the blowing side of the vacuum unit is arranged a medium passage 113
to the conveying piping 100 on its reversed supply side. In the conveying pipe
100
is formed a channel section 114 which is connected to the conveying pipe in a
5 section between the valve element 126 and the separator device 20 or
directly to
the separator device, whereby the circulation direction of conveying air is
reversed
only in a section of the circuit, mainly in the section of the conveying pipe
100.
Then, possible blockages are sucked "backwards" in relation to the normal
circulation direction.
The invention thus relates to a method in a pneumatic material conveying
system,
such as a waste conveying system, which conveying system comprises at least
one feed point 61 of material, particularly of waste material, a material
conveying
pipe 100 which is connectable to the feed point 61, a separator device 20 in
which
the material being conveyed is separated from conveying air, and means 3 for
providing a pressure difference in the conveying pipe 100 at least during the
conveyance of the material. At least a part of the conveying piping 100 is
connectable as a section of a circuit in which conveying air is circulated at
least
during the conveyance of the material with a pump device 3 the suction side of
which is connected to at least one separator device 20 and further to the
conveying pipe 100 on its return side so that at least part of conveying air
on the
pressure side of the pump is led in the circuit on the supply side of the
conveying
pipe 100 via an ejector device 9.
According to a typical embodiment, at least part of conveying air is
circulated via
the ejector device 9 in which extra air is brought to the circuit.
At least part of blowing air of the pump device 3 is employed as the actuating
medium of the ejector device 9.
According to an advantageous embodiment, in the material feed stage,
underpressure is provided from the feed point to the conveying pipe to at
least a
part of the conveying piping 100 with the pump device, whereby the outlet air
channel of the blowing side of the pump device 3, such as a fitting 93, is
open.
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According to an advantageous embodiment, in the conveying stage, at least the
main part of air on the blowing side of the pump 3 is circulated in the
circuit on the
supply side of the conveying pipe 100.
According to an advantageous embodiment, in the method, in the circuit is
brought
make-up air via at least one air inlet 107, 107', 93 which advantageously
comprises a valve element 128, 128', 96.
According to an advantageous embodiment, the method comprises an operating
mode in which air is removed from the circuit via at least one air outlet,
such as the
fitting 93, which advantageously comprises a gate/regulating element, such as
the
valve element 96.
According to a yet further advantageous embodiment, the circulation of air in
the
circuit, which comprises at least a part of the conveying piping 100, is
regulated
and/or controlled and/or opened or closed by gate/regulating elements, such as
valve elements 122, 124, 125, 126, 127, VA, VB, VC, VD, which are arranged in
the
circuit.
According to a typical embodiment, in the method, underpressure is provided in
the circuit with at least one pump device 3 the suction side of which is
connected
to the separator element 20 or to the conveying pipe 100 via the air channel
105
leading to it.
According to a yet further embodiment, in the method, pressure is provided in
the
circuit with at least one pump device 3 the blowing side of which is connected
to
blow in the circuit.
According to an advantageous embodiment, the method comprises an operating
mode in which conveying air circulation is connected in the reverse direction
at
least in a section of the circuit, which section is formed by at least a part
of the
conveying pipe 100, advantageously for removing a blockage.
According to a further advantageous embodiment, the method comprises an
operating mode in which at least a part of the conveying piping 100 is flushed
and/or dried with air by circulating the conveying air in the circuit,
particularly by
blowing in the circuit with the pump device 3.
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Typically in the method, material is fed from the material feed points 61
which are
waste feed points, such as waste bins or waste chutes.
Typically between the material feed point 61 and the conveying pipe 100, there
is
at least one valve element 60 by opening and closing of which the feed of
material
and/or make-up air to the conveying pipe is regulated.
According to an advantageous embodiment, the valve element 60 between the
material feed point 61 and the conveying pipe 100 is closed advantageously
after
a certain time from opening so that the valve 60 of the previous feed point is
still
open when the valve of the next feed point 61 is opened.
The invention also relates to an apparatus in a pneumatic material conveying
system, such as a waste conveying system, which comprises at least one feed
point 61 of material, particularly of waste material, a material conveying
pipe 100
which is connectable to the feed point 61, a separator device 20 in which the
material being conveyed is separated from conveying air, and means 3 for
providing a pressure difference in the conveying pipe 100 at least during the
conveyance of the material. The apparatus comprises a circuit which comprises
at
least a part of the conveying piping 100, in which circuit conveying air is
circulatable, and means which are arranged to circulate conveying air at least
during the conveyance of the material with a pump device 3 the suction side of
which is connected to at least one separator device 20 and further to the
conveying pipe 100 on its return side so that at least part of conveying air
on the
pressure side of the pump is led in the circuit on the supply side of the
conveying
pipe 100 and that the apparatus comprises an ejector device 9 which is
arranged
in the circuit on the blowing side of the pump device 3 between the pump
device 3
and the conveying pipe 100.
According to an advantageous embodiment, the actuating medium of the ejector
device 9 is blowing air of the pump device 3.
Typically, the ejector device 9 comprises a fitting 93 for leading another
medium
flow in the actuating medium flow. The other actuating medium flow is
advantageously a gas flow, such as an air flow, for bringing extra air in the
circuit.
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In the material feed stage, underpressure is provided from the feed point to
the
conveying pipe to at least a part of the conveying piping 100 with the pump
device
3, whereby the outlet air channel of the blowing side of the pump device 3,
such as
the fitting 93, is arranged to open.
According to an advantageous embodiment, in the circuit, which comprises at
least a part of the conveying piping 100, are arranged gate/regulating
elements,
such as valve elements 122, 124, 125, 126, 127, VB, VC, VD, by means of which
the circulation of conveying air can be regulated and/or controlled and/or
opened
or closed.
According to a yet advantageous embodiment, the apparatus comprises at least
one air inlet 107, 107', 93 which advantageously comprises a valve element
128,
128', 96 for bringing air in the circuit from outside it.
According to a further advantageous embodiment, the apparatus comprises at
least one outlet 93 which advantageously comprises a gate/regulating element,
such as the valve element 96, for removing at least part of air from the
circuit.
Typically, the means for providing a pressure difference comprise at least one
pump device 3 the suction side of which is connected to the separator element
20
or the air channel 105 leading to it. There can be several pump devices and
they
can be connected in the circuit in parallel or in series, whereby the suction
side of
the first pump device is connected to the separator device 20 and the blowing
side
to feed air on the suction side of the second pump device. The blowing side of
the
second pump device is then arranged to blow in the ejector device 9.
According to another embodiment, the means for providing a pressure difference
comprise at least one pump device 3 and means 110, 122; 113, 124 for
connecting the blowing side of at least one pump device to blow in the
circuit.
According to another advantageous embodiment, the apparatus comprises means
113, 114, 122, 124, 125, 126 for connecting the conveying air circulation in
the
reverse direction in at least a section of the circuit, at least part of which
is formed
by the conveying pipe 100.
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14
According to a yet further advantageous embodiment, the apparatus comprises
means for flushing at least a part of the conveying piping 100 with air and/or
for
drying by circulating the conveying air in the circuit, particularly by
blowing.
According to an advantageous embodiment, the material feed points 61 are waste
feed points, such as waste bins or waste chutes.
Between the feed point 61 and the conveying pipe 100, there is at least one
valve
element 60 by opening and closing of which the feed of material and/or make-up
air to the conveying pipe is regulated.
The suction provided by the vacuum unit 3 to the conveying pipe 100, in the
figure
from the side of the separator element 20, is advantageously greater than the
blow, whereby conveyance takes place in underpressure. The suction being
greater than blowing, underpressure is provided in the piping, whereby waste
can
be sucked inside the piping from a funnel of the feed station 61.
The suction being greater than the blowing, which is the target in the system
according to the invention, material fed to the conveying pipe, particularly
waste
material, will not be compressed and compacted, but will be able to travel
"freely"
in the pipe conveyed by conveying air. Then, the potential of the material
being
conveyed to form blockages is considerably lower than in a situation in which
the
blowing is greater than the suction, whereby there is a risk that the material
being
conveyed will accumulate and block the conveying pipe. Furthermore,
underpressure decreases the power required to convey the material, because
even partial underpressure in relation to the material portion being conveyed
on
the side of the conveying direction considerably decreases air drag, among
others.
In the figure, arrows designate the direction of motion of air in the piping
in the
operating mode.
The outlet valve 60 of the feed point 61 is opened and closed so that material
portions of suitable size are conveyed from the feed point 61 to the conveying
pipe
100. Material is fed from the feed point 61, such as a waste container, when
after
the container is full, the outlet valve 60 is opened either automatically or
manually.
The system typically operates as follows: An outlet hatch 21, 21' of at least
one
separator device 20, 20' is closed and a valve 126 between the main conveying
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pipe 100 and the separator device 20 is open. The pump unit 3 maintains
underpressure in the main conveying pipe 100.
All outlet valves 60 in the vicinity of the feed points 61 i.e. waste
containers are
5 closed. In the start situation 100, the valve VD is closed.
Let us assume that a waste container of the feed point 61 belonging to the
circuit
of the operating area 100D of the conveying pipe 100 is to be emptied. Based
on
an emptying signal, the outlet valve 60 is momentarily opened, e.g. for 2-10
10 seconds, whereby the material being conveyed, such as waste material,
conveys
from the effect of underpressure to the conveying pipe 100D. The outlet valve
60
is typically closed after a few seconds after the start situation. The vacuum
pump
unit 3 maintains desired underpressure. The valve VD is opened, whereby in the
circuit of the piping is provided air circulation and possibly also a blowing
effect i.e.
15 pressure effect and suction effect which conveys the material portion being
conveyed along the piping to the separator device 20. One or more feed points
61
are emptied. According to an advantageous embodiment, the one of the feed
points of the desired operating area which is in the conveying direction
closest to
the separator device 20 is emptied first, and then the next closest feed point
and
so on until the desired feed points have been emptied.
When the separator device 20 is full, the valve 126 of the conveying pipe 100
closes and a control valve 23 opens, whereby the actuator 24 of the outlet
hatch
21 of the separator device opens the outlet hatch 21 and the material
accumulated
in the separator device is emptied in the compactor device 50 and further in
the
waste container 51. The outlet hatch 21 of the separator device 20 is closed
and
the valve 126 opened.
After this, the start situation is reverted and the emptying process can be
repeated
or the emptying of some other feed point/feed points can be implemented.
The waste container 51, such as a waste freight container, is replaced or
emptied
when it is full.
The system can also comprise several separator devices 20, 20' in which
material
conveyance is controlled, e.g. based on the sort of the material or the
capacity of
the system.
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16
It is obvious to those skilled in the art that the invention is not limited to
the
embodiments described above, but it may be varied within the scope of the
enclosed claims. When necessary, the features possibly described in this
specification together with other features may also be used separately from
each
other.
