Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02390620 2001-11-19
Separator for Separating Solid Matter from a Liquid-Solid Mixture Collected
at a Dental Treatment Centre
The present invention relates to a separator for separating solid matter from
a liquid-solid
mixture that has been suctioned from patients' mouths and collected at a
dental treatment centre,
said separator having a housing that incorporates an inlet for the mixture and
an outlet for liquid,
a solid material separation area being incorporated in said housing. The solid
matter may contain
drilling dust, fragments of bone, particles of amalgam that contain mercury,
as well as particles
of dental metals such as gold: It is mainly the mercury that for reasons of
environmental
protection is to be prevented from getting into the waste water.
For this reason, for the past twenty years or so a large proportion of solid
matter has been
separated from the mixture. In principle, there are three ways of doing this,
namely by
precipitating the heavier particles by gravity; precipitating them in
centrifuge drums or the like,
with active support from centrifugal force; and the retention of particles
above a certain size by
filters, screens, and the like.
Each of these three possibilities entails disadvantages: the retention of
solid matter by filters and
screens that are placed in the flow path of the mixture results in relatively
rapid clogging of the
filtering material or meshes; precipitation by gravity requires the slow and
unperturbed passage
of the mixture through the solid-matter separation chamber, which is difficult
to achieve during
CA 02390620 2001-11-19
dental activity since very variable quantities flow through, and separation by
centrifuges requires
costly equipment with drive motors, control systems, and the like.
One objective of the present invention is to improve the gravity separation of
solid matter from a
dental mixture of liquid and solid material in a compact separator, when, for
example,
throughputs of 6 to 8 litres per minute can be processed.
Another objective of the present invention is the additional separation of the
suction air from the
mixture of liquid-solid matter before said mixture enters the solid matter
separator chamber, so
that three-phase separation is provided.
A further objective of the present invention is the separation of solid
material from a mixture of
suction air, liquid, and solid matter, when the suction air is first separated
from the mixture of
liquid and solid matter, then the solid material is precipitated out of the
liquid by gravity, after
which the suction air and the liquid that contains no solid matter are mixed
together once again
and delivered to the suction pump together.
A further objective of the present invention is the additional separation of
environmentally
hazardous heavy-metal ions from the processed water that leaves the solid-
material separation
chamber.
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These and other objectives can be achieved with a separator according to the
present invention,
the solid material separation chamber of which has a first, lower
sedimentation zone that is
connected to the mixture inlet so as to permit a flow between them, and at
least one second
sedimentation zone that is arranged above the first sedimentation zone, a free
overflow being
formed at the flow end as an outlet for liquid. Because of the liquid overflow
that is located
above, at least a significant part of the solid material separation chamber is
flooded, so that the
arrangement of at least two sedimentation zones one above the other ensures a
sufficiently large
sedimentation area in a small space, wherein good sedimentation conditions can
exist even in the
case of widely varying quantities flowing through them.
In a first, preferred embodiment, provision is made such that there are at
least two sedimentation
pans arranged coaxially one above the other in the solid material separation
chamber, each of
these forming a sedimentation area of the second sedimentation zone. In
particular; the
sedimentation pans are provided with non-aligned base openings and hollow
cylinders that
extend upward and surround these, and predetermine a sedimentation level. Each
of the off-set
base openings effects a lateral deflection of the flow between the
sedimentation pans; this
extends the upward flow path.
In a second preferred embodiment, provision is made such that the second,
upper sedimentation
i
zone has at least two chambers that are separated by overflow ridges, each
forming a
sedimentation area, in the last of which there is a liquid outlet formed as a
free overflow.
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The chambers that are separated by overflow ridges are
formed in particular in an insert element that can be
inserted into the sedimentation container; this element has
two diametrically opposed base openings, the first base
opening forming a flow connection from the first
sedimentation zone that is located below; the fluid outlet
being routed through the second base opening.
In this embodiment, the solid material separation
chamber is provided with a sedimentation container for solid
material that can be connected, so as to provide a flow, to
an upper feed line and to a lower waste water channel, and
from the fluid outlet in the last chamber a tube that can be
connected to the waste water channel is routed downward
through the sedimentation container. Here, too, at least a
considerable part of the solid material separation chamber
is flooded, and the flow is reversed.
In another embodiment, there are at least two
sedimentation pans arranged coaxially one above the other in
the solid material separation chamber, each of these forming
a sedimentation area of the second sedimentation zone.
The liquid separator can also include a pre-
separation area with pans through which the flow passes from
the top down in the manner of a cascade, and from which the
mixture then flows through an annular inlet chamber outside
the upper sedimentation zone, downward into the first lower
sedimentation zone. The inlet chamber, which is narrow,
makes a significant contribution to non-turbulence in the
solid material separation chamber, since turbulence can
hardly be transmitted from the inlet chamber into the
interior of the sedimentation container.
In one preferred embodiment, the annular inlet
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chamber is extended downward by a downflow baffle so that
the reversal of flow is governed by the lower edge of the
downflow baffle. The lower edge of the downflow baffle is
not horizontal, but has a lowest area beneath the mixture
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inlet. The shape of the lower edge of the downflow baffle is so selected that
the space between
the mixture inlet and the edge is of almost equal size at each location. When
separation begins a
flow will be established in which a vertical downward component away from the
mixture inlet
predominates until such time as the material that is forming the sediment
itself blocks this
preferred flow path. This lengthens the flow, and it increasingly receives a
peripheral component
along the downflow baffle. Because of this, not only is the height of the
sedimentation raised to
a level that is significantly higher than the lowest area of the downflow
baffle, so that a very large
capacity of the sedimentation container is achieved, and the sedimentation
time is not only
maintained, but is even prolonged.
In another preferred embodiment of the present invention, the suction air that
imparts the
movement is separated from the mixture in an air separation chamber that is
formed within the
housing, above the sedimentation container, and in which the air is routed
over guide surfaces
and drawn off through an air outlet that is preferably provided in a pipe that
is routed centrally
downward in the housing. In this embodiment, the liquid that is for all
practical purposes free of
environmentally hazardous material can pass not only into the waste water
channel, but can also
be returned to the suction air if, for example, a water ring pump that
requires sealing liquid is
used as the suction pump. In this case, the liquid that has been processed can
be drawn into the
flow of air in an outlet chamber that is arranged beneath the sedimentation
chamber, and then
passed out of this.
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If the second sedimentation zone is provided into an insert element, this also
has a base opening
through which the pipe of the air outlet is led.
Lamellar plates that rise in the direction of the in-flow can be provided
within the annular inlet
chamber into the first sedimentation zone, particularly if an air separation
chamber is formed; the
radial edges of these plates are arranged so as to be spaced above each other.
This means that the
inlet chamber is divided into a series of slits between the plates, and this
slows down the mixture
that is flowing in.
In order to remove dissolve mercury compounds from the liquid, provision can
be made such that
an insert and/or filling that binds mercury or mercury ions, for example
activated charcoal, can be
provided in the second sedimentation zone.
The present invention will be described in greater detail below on the basis
of the drawings
appended hereto, without being restricted thereto. The drawings show the
following:
Figure 1: a longitudinal cross section through a first embodiment of a
separator;
Figure 2: a longitudinal cross section through a second embodiment of a
separator;
Figure 3: a longitudinal cross section through a third embodiment of a
separator;
Figure 4: a perspective view of a sedimentation pan, as viewed from above;
Figure 5: a perspective view of a sedimentation pan, as viewed from below;
Figure 6: a longitudinal cross section through a fourth embodiment of a
separator;
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Figure 7: a longitudinal cross section through a fifth embodiment of a
separator, along the
line V-V in Figure 8;
Figure 8: a plan view of an insert element of the sedimentation container;
Figure 9: a longitudinal cross section through a sixth embodiment of a
separator.
Figure 1 shows a separator that is used to separate solid material from a
liquid, the mixture that is
suctioned off from a patient's mouth by a suction device 62 (Figure 3) being
separated from the
suction air in a preceding air separator, and then being carried off through a
pressure lock, a
valve, or the like from the vacuum stage of a dental suction system. Thus, the
separator is at
normal atmospheric pressure and the mixture passes through the mixture inlet 4
into the housing
1, within the mixture inlet area of which there is a central annular wall 33,
beneath which the
outlet 24 for the liquid that has been cleansed of solid matter is provided
and which screens the
liquid outlet 24 from the mixture inlet area.
Beneath the mixture inlet area, the housing 1 encloses a solid material
separation chamber 12
with a sedimentation container 13, in which the solid material is separated
from the liquid in two
sedimentation zones 22, 36. Above the sedimentation container 13 there is a
pre-separation area,
mainly for coarser and heavier particles, in which there are pans 27 through
which the mixture
flows from top to bottom. These pans incorporate an inclined bottom 28 and, in
particular, three
annular ridges 29 so that each in each instance three cascade-like concentric
precipitation
chambers are formed, one after the other.
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The bottom 28 of the upper of the two pans 27 is
inclined inward and incorporates a central opening 30 that
leaves the passage to the second pan 27 that is located
beneath the first pan unobstructed, and through which the
annular wall 33 extends from the central area of the second
pan 27. The second pan 27 has a bottom 28 that is inclined
outward, and there are also three annular ridges 29 on this;
these also form concentric, cascade-like, sequential
precipitation chambers. Liquid and solid matter flow over
the outer edge of the second pan 27 down into a narrow
mixture delivery channel 21 formed by a narrow annular
chamber 50 to the first, lower sedimentation zone 22 that is
provided in the lower area of the sedimentation container
13; a closed drain opening (not shown herein) can be
provided at the lowest point of the inclined housing
bottom 2. The mixture delivery channel 21 is defined to the
outside by the housing wall and to the inside by the outer
defining walls of a plurality of sedimentation pans 14 that
are arranged coaxially one above the other to form a tube,
and these form a second sedimentation zone 36. The
sedimentation container 13 is always full of lzquid during
operation, since the liquid outlet 24 from the second
sedimentation zone 36 is provided above the uppermost
sedimentation pan 14 as a free overflow on the vertical
drain tube 25, the upper end of which extends-in Figure 1-
beyond the uppermost sedimentation pan 14. At the lower end
of the tube formed by the defining walls 20 of the
sedimentation pans 14, the flow of liquid is deflected
inwards and upwards, when it is mainly fine and very fine
particles of solid material are carried along, and these
then precipitate out in the sedimentation pans 14 through
which the flow moves upwards from below.
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Each of the sedimentation pans 14 has-a bottom 15 in which there is a
plurality of openings that
are surrounded by hollow cylinders 16 that extend upwards and by truncated
hollow conical stubs
17 that extend downward. The upper sides of the hollow cylinders 16 define the
maximal
sedimentation level in each sedimentation pan 14. The outer defining wall 20
of each
sedimentation pan 14 also extends downward, so that a free space 18 is left
between the top side
of the hollow cylinders 16 and the underside of the bottom 15 of the
sedimentation that is
arranged above it. The truncated hollow conical stubs extend into this space.
In addition, the
sedimentation pans 14 also incorporate inner defining walls that surround a
central opening and
through which the drain tube 25 for the liquid extends downward, and with
which a lower
housing outlet 26 is associated. The hollow cylinders 16 and the hollow
truncated cones 17 are
each arranged in rows that extend radially, a short row being inserted between
each two rows that
end at a greater distance from the outer defining wall 20, these short rows
beginning at the outer
end and ending at the approximately half the radius of the pan.
In order to permit the best possible precipitation of even very fine particles
in the sedimentation
pans 14, the openings in the bottom 15 of the sedimentation pans 14 are not
aligned, which is to
say they do not form continuous flow channels; rather, the liquid emerging
from the hollow
cylinders 16 must be diverted laterally within the free space 18 into at least
one of the adjacent
hollow truncated cones 17.
As can be seen in Figure 4 and Figure 5, the outer defining walls 20 of the
sedimentation pans 14
are provided with three snap tabs 31 and corresponding snap recesses 32 so
that they can be fitted
CA 02390620 2001-11-19
together one above the other and locked into position. The recesses 32 are not
positioned
centrally between the snap tabs 31, so that when the sedimentation pans 14 are
positioned one
above the other they are offset not by 60 , but-viewed in the direction
indicated by the arrow in
Figure 4-by less than 60 relative to each other.
In the embodiment shown in Figure 4 and Figure 5, the rows 18 each comprise
five hollow
cylinders 16, and the rows subtend an angle of 20 with each other. Centrally
between two rows
of five hollow cylinders 16 and truncated hollow cones 17 there is a row of
three hollow
cylinders 16 and truncated hQllow cones 17. Rotating the uppermost
sedimentation pans 14 by
20 , 40 , and 60 thus aligns the rows and the openings line up with each
other. Rotation
through 10 , 30 , and 50 places a row of five hollow cylinders/hollow
truncated cones and a row
with three hollow cylinders/hollow truncated cones above each other, when the
hollow cylinders
16 of the lower sedimentation pans14 are offset relative to the hollow
truncated cones 17 of the
upper sedimentation pans 14 only in a radial direction.
In contrast to the foregoing, in the longitudinal cross sections in Figure 1
to Figure 3, the
arrangements of the hollow cylinders/hollow truncated cones coincide only in
every fourth
sedimentation pan 14, as can be seen in the cross sections through the lowest
and the uppermost
(fifth) sedimentation pan 14. This arrangement results if the angle of 120
between the two
adjacent snap tabs is divided in the ratio of 55 and 65 so that coincidence
is achieved only after
the fourth sedimentation pan, since only then does the angle of 4 x 55 = 220
, or 4 x 65 = 260
represent an integer multiple of the angle of 20 between two rows of hollow
cylinders/ hollow
-o
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truncated cones 16, 17. (In each instance, all angle data relate to the
intended radial centre plane
of the snap tabs 31, snap recesses 32, hollow cylinders 16, and truncated
hollow cones 17).
Figure 4 shows the cross section lines A, B, C, D, and E of the five,
assembled sedimentation
pans 14 as in Figures 1 to 3.
It is preferred that the uppermost sedimentation pan 14, which is to say the
last-as viewed in the
direction of flow-before the liquid outlet 24, contain a filling 19 than binds
dissolved mercury
ions and/or very finely dispersed elementary mercury or mercury vapour. This
filling can be in
the form of metal fibres, a metal mesh, a metal foam, etc., of a mercury
alloying or metal (iron,
zinc, tin, magnesium, copper, etc.) that is a base in relation to mercury. An
ion-exchange filling,
for example thiourea, thiourea, or a similar ion-exchange material, can be
used to remove
mercury ions. The filling 19 can also contain activated charcoal.
In the embodiment that is shown in Figure 2, the housing 1 also contains an
air separation
chamber 5 that is located above the solid material separation chamber 12, so
that the suction air
that carries the mixture into the separator housing 1 by way of the line 63
(Figure 3) is separated
in the same device before the solid material is separated out. The air
separation chamber 5
contains an apron-like and domed deflection surface 6, 7 that is deep-drawn in
the middle, the
mixture outlet 4 being incorporated above and outside the apron-like
deflection surface 6. The
suction air is passed to an air outlet 10 that is provided on an air outlet
tube 9 that extends
vertically in the centre of the air outlet 10, with its upper end within the
annular wall 33 of the
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pre-separator that, in this embodiment; has an upper opening 8 into which the
deep-drawn area of
the dome-like deflection surface 7 extends. The air outlet tube has at its
lower end a connector
34 for a line that runs to the suction pump. The solid material separation
chamber 12 is
configured as has been described in connection with Figure 1. However, the
outlet tube opens
out differently, in a trap chamber 35 that is arranged beneath the housing 1,
and which
incorporates a lower housing outlet 26 for the liquid that has been processed.
The embodiment shown in Figure 3 also has a separator, in the housing 1 of
which there is an air
separation chamber 5, as in Figure 2, and a solid material separation chamber
12. What is
different in this design is the configuration of the outlet area for air and
liquid, since the upper
end of the drain tube 25 includes the air outlet 10 and the liquid, outlet 24.
In this embodiment,
the air that has been separated out is once again combined with the liquid
that has been
processed, and there is a line 65 on the housing outlet 26 that is associated
with the outlet tube
25, said line 65 going to a suction pump that is configured as a water ring
pump and is thus
suitable for moving liquid.
Figure 6 shows a second version without air separation, in which the mixture
once again enters
through the mixture.inlet 4 into the sedimentation chamber 13, which is fitted
with a cover 58
and the inlet chamber 50 is partitioned off from the central area by an
annular baffle 52. Beneath
the inlet chamber 50, the sedimentation container 13 has the first
sedimentation zone 22 in which
mainly coarser and heavier particles collect and through which the mixture
flows downward from
above. At the lower end of a downflow baffle 57 that forms an extension of the
annular baffle 52
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over a part of the periphery, the flow in the liquid is
deflected inward and upward into the second sedimentation
zone 36, when mainly fine and very fine particles of solid
material are carried along with it. As soon as the
sedimentation reaches the level hl that is determined by the
lower edge of the downflow baffle 57, the flow path that has
been described is blocked off and the flow shifts
peripherally along the downflow baffle 57 as far as its end,
so that the flow path is not shortened, despite a growing
sedimentation surface. The maximal sedimentation level h2 of
the first sedimentation zone 22 is defined by the lower edge
of the annular baffle 52.
The second sedimentation zone is provided in an
insert element 42 that is installed in the sedimentation
container 13, provided with the annular baffle 52, and which
has a bottom 43 from which-as can be seen in Figure 8-
parallel overflow ridges 47 extend upward; these define the
chambers 48. The bottom 43 has a first opening 45 that
forms the flow connection to the first sedimentation
zone 22, and a second opening 46 in the last chamber 48,
through which a drain tube 25 is routed through the
sedimentation chamber 13 downward into an outlet chamber 35.
The upper edge of the tube 25 forms the liquid outlet 24
from the sedimentation chamber 13 in the form of a free
overflow over which, after passing through the chambers 48
of the second sedimentation zone 36, liquid that is for all
practical purposes free of solid material flows. The outlet
chamber 35 is provided with an outlet 26 that can be
connected to a waste water drain line.
The mixture outlet 24 is at the same level as, or
preferably slightly higher than the upper edge of the
highest overflow ridge 47, so that the sedimentation
container 13 is filled with liquid right up to this upper
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edge. Damping baffles 49 are also provided to prevent
turbulence, at least in the inlet chamber 50, since such
turbulence could disrupt the sedimentation process.
As is shown in Figure 6, the first opening 45 in
the insert element 42 can also be covered by a layer 55 that
binds dissolved mercury ions and/or finely dispersed
elementary mercury or mercury vapour. The layer 55 can, for
example, be a metal tissue, woven metal, metal foam, etc. of
a metal such as iron, zinc, tin, magnesium, copper or the
like that alloys with mercury or is a base with respect to
mercury. In order to remove the mercury ions, the insert 55
can also possess ion-exchanging properties and can contain
thiourea, thiourea, or similar ion exchanging materials.
The insert 55 can also contain activated charcoal.
In the version shown in Figure 7, the separator
has a housing 1 that also incorporates an air separation
chamber 5 above the sedimentation chamber 13, so that the
suction air that carries the mixture that is drawn into the
mixture inlet 4 by way of a line 63 is separated in the same
device before the solid material is separated out from the
mixture. The air separation chamber 5 contains an apron-
like deflection surface 6 and a dome-like deflection
surface 7 that is deep drawn in the middle, the mixture
inlet 4 being provided above and outside the apron-like
deflection surface 6. The suction air is passed to an air
outlet 10 that is provided and a tube 9 that rises centrally
in the sedimentation container 13, the upper end of which is
higher than the underside of the apron-like deflection
surface 6. The annular baffle 52, which is connected to the
bottom 43 of the insert element 42, has a deflecting baffle
59 that rises into the apron-like deflection surface 6 about
half-way round the periphery, on both sides of the mixture
inlet, so as
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to prevent the suction air from having a direct path to the air outlet 10. The
mixture, freed of air,
leaves the air separation chamber 5 through a mixture outlet 41 that extends
peripherally round
the apron-like deflection surface 6 and falls in the inlet chamber 50 that is
located below this and
which is divided into a number of slits by inclined lamellar plates that rise
transversely to the
direction of the inflow. The radial edges of each of the lamellar plates 51
that follow each other
in sequence lie approximately above each other.
As is shown in Figure 8, in this embodiment the insert element 42 has a third,
central opening 44
through which the tube 9 passes. The tube 9 opens out into the outlet chamber
35, below the
sedimentation chamber 13, in which the air that has been separated out is once
again combined
with the liquid that has been processed. There is a line 65 on the housing
outlet 26 that is
associated with the outlet chamber 35, said line 65 going to a suction pump
that is configured as
a water ring pump and is thus suitable for moving liquid.
In order not to disrupt the sedimentation of the remaining, mainly fine
particles of solid material
in the second sedimentation zone 36, this is screened off from the air
separation chamber 5 by a
more or less conical cover 53 that incorporates a central opening through
which the tube 9 passes
centrally.
The sedimentation chamber 13 can be removed both from the outlet chamber that
forms the
lower part of the housing 1 as well as from the upper part of the housing 1
that encloses the air
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separation chamber 5, and when appropri ately filled with sedimented solid
material this will be
replaced by an empty sedimentation chamber 13.
Figure 9 shows another embodiment of a separator with an air separation
chamber 5 above the
sedimentation container 13; this embodiment differs from that shown in Figure
7 in a few details,
which mainly serve to lengthen the flow path through the first sedimentation
zone 22. As
compared to the one shown in Figure 7, the downflow baffle 57 reaches much
further downward
into the sedimentation chamber 13, and the lower edge extends horizontally
through an angle of
approximately 240 , and ends by sloping upward. In other words, the downflow
baffle 57 has an
approximately V-shaped section 60 on the side that is opposite the mixture
inlet 4. Because of
this, after the increase in the direct flow path, as soon as the sediment has
reached level hi, the
liquid must flow along a peripheral diversion of at least 120 in order to
reach the interior of the
first sedimentation zone 22 through the V-shaped section 60. The maximal
sedimentation level
h2
is defined by the lower edge of the annular baffle 52 in the area of the
section 60.
In addition, the cover 53 of the second sedimentation zone 36 is an inclined
disc, at the lowest
point of which there is an opening 61 in the annular baffle 52 that permits
the return flow of
liquid that has been separated out from the deflected air and has collected on
the cover 53 into
the inlet chamber 50.
