Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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MATERIAL SEPARATION SYSTEM FOR VACUUM TRUCK
This invention relates to a vacuum truck for vacuum extraction to a
storage tank of liquids and solids from an area to be cleaned, which uses a
separation system within the storage tank to remove liquid content from solids
content so as to allow the liquid to be returned to the area and to increase
the
amount of available transportation area within the tank for the solids to be
transported to a remote location.
BACKGROUND OF THE INVENTION
Vacuum trucks are well-known and widely used for excavation or
extraction of particulate material by vacuum from an area to be cleared, with
the
material collected being transported through a vacuum hose into a storage tank
from
which the material is separated from the air before the air enters the vacuum
pump.
Such vacuum trucks are commonly used for clearing pipes and other
areas where a collection of solid material needs to be extracted from an area
containing water. Thus a blocked sewer or drainage pipe contains water which
can
be returned to the pipe and a quantity of solids which must be removed.
One problem which arises with vacuum trucks of this type is that it is
desirable to increase as far as possible the amount of solids which can be
collected
so as to transport as much as possible of the material which must be removed
while
returning liquid to the area being cleaned. It will be appreciated that to
maximize the
amount of material carried in a load reduces the number of loads which must be
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transported with the potential of significantly reducing total working time to
clear a
particular area or blockage.
US Patent 5,722,113 (of the present inventor Baziuk) issued March 3rd
1998 shows an arrangement for collecting dust and moisture where separate
collection tanks are provided on each side of the tank and contain hanging
chains
which form a screen. There is no disclosure of separation of liquid and solids
within
the tank.
US Patent 4,016,994 (Wurster) issued April 12th 1977 shows a two
tank system for collecting air transportable material which may be wet or dry
but
does not act to separate the wet from the dry.
US Patent 4,904,126 (Voith) issued February 27th 1990 shows a
vacuum truck for collecting primarily dry material which uses filter
cartridges to
separate the particulate materials from the air.
US Patent 6,453,584 (Buckner) issued September 24th 2002 shows an
arrangement in which the collected materials and separated into liquid and
solids
components using a vibrating screen onto which the material is deposited with
the
liquid falling through into a separate container. The materials are
continually
discharged so that the tank is not required as a transport container, thus
allowing the
separation system to take up a significant part of the tank.
US Patent 6,604,304 (Slabach) issued August 12th 2003 shows a
vacuum system with a slurry tank for transporting the extracted slurry
material.
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There is no attempt to separate the liquid and solids content so that the
total of the
slurry needs to be transported.
US Patent 5,295,317 (Perrott) issued March 2snd 1994 shows an
excavation machine in which the collected materials and separated into liquid
and
solids components using a rotating screen. The materials are continually
discharged
so that the tank is not required as a transport container, thus allowing the
separation
system to take up a significant part of the tank.
SUMMARY OF THE INVENTION
It is one object of the invention to provide an improved vacuum truck
where there is provided a separation system within a transportation and
storage tank
to remove liquid content from solids content so as to allow the liquid to be
returned
and to increase the amount of available transportation area within the tank
for the
solids to be transported to a remote location.
According to one aspect of the invention there is provided a vacuum
truck comprising:
a truck frame mounted on ground wheels;
a vacuum pump mounted on the truck frame for generating an air flow
through the pump to form a vacuum inlet on one side of the pump and an air
outlet
on an opposed side of the pump;
a vacuum hose having an inlet nozzle for communicating air flow from
a material to be vacuumed to carry the material in the air flow to a hose
outlet;
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a storage tank having a tank inlet connected to the hose outlet of the
vacuum hose for receiving the material carried in the air flow;
at least one tank extraction outlet connected by a duct to the vacuum
inlet of the pump such that air flow is drawn from the tank by the vacuum pump
through the duct which generates the air flow in the vacuum hose to carry the
material;
the tank being arranged such that the materials carried in the airflow
are discharged from the airflow as the airflow passes through the tank from
the
vacuum hose to the tank extraction outlet;
the tank including a separation system therein for separating the
materials generally into a liquid component and a solids component;
a liquid pump mounted in the tank for extracting the separated liquid
component from the tank to increase a storage capacity of the tank for the
solids
component to be collected and transported in the tank on the truck to a remote
location for discharge;
a discharge door at one end of the tank for discharging the collected
solids component;
a lifting arrangement for tilting the tank so as to discharge the collected
solids component through the discharge door;
the separation system including a generally upstanding dividing wall
across the tank dividing a solids collection area on one side from a liquid
collection
area on the other side, with the solids collection area being located adjacent
the
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discharge door, with the water pump having an inlet located in the liquid
collection
area and with the tank inlet located in the solids collection area;
the dividing wall having a bottom wall portion, which is substantially
imperforate and has a top edge at or adjacent a weir over which liquid can
flow into
5 the liquid collection area;
the dividing wall having an upper screening section, which is
perforated to allow the liquid to pass over the top edge into the liquid
collection area
while restricting passage of the solids;
wherein the upper screening section includes a hanging curtain formed
by a series of side by side lengths of chain.
Preferably the upper screening section extends from the top edge to a
top wall of the tank to allow the tank to be filled to the top wall with the
solids.
Preferably the upper screening section includes a hanging curtain
formed by a series of side by side lengths of chain. Such hanging chain
lengths are
self cleaning and resistant to damage from heavy components in the solids.
Preferably the lengths of chain are connected only at a top end so that
the other end of each length of chain is free and the length of chain is
suspended
vertically with the other end of the lengths of chain in contact with or
closely adjacent
the top edge of the bottom wall portion.
Preferably the upper screening section includes a perforated screen
support on the side of the curtain which is within the liquid collection area
to prevent
the curtain from being forced into the liquid collection area by the weight of
collection
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of solids within the solids collection area and thus to hold the solids in the
solid
collection area.
Other types of screening section can be used but the chains are
particular effective in that they are rugged and resistant to damage and self
cleaning.
The separating action is relatively crude since some solids can enter
the liquid area without causing a breakdown, blockage or damage. However the
intention is to extract as much water as is reasonably possible with a simple
rugged
system so as to increase the amount of solids contained.
Preferably the bottom wall portion is mounted for pivotal movement
about a horizontal axis at or adjacent the top edge so as to pivot during
tilting of the
tank to open and allow discharge of materials collected at a bottom of the
liquid
collection area. Also any liquid collecting behind the bottom portion which
acts as a
door can flow over the bottom of the tank in a cleaning action to help wash
away any
remaining solids at the bottom of the tank
Preferably the pivotal bottom wall portion or door reaches substantially
to a bottom wall of the tank so that effectively all material at the bottom
wall can
discharge by flowing over the bottom of the tank when the tank is tilted. Any
water
remaining at the bottom of the water collection area can be used to rinse the
remaining solids from the tan.
Preferably there is provided a back-stop to prevent pivotal movement
of the bottom wall portion or door in the reverse direction into the liquid
collection
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area caused by the weight of solids collected in the solids collection area
and resting
against the door.
Preferably the liquid pump is mounted in the liquid collection area with
its inlet in a caged area inside the liquid collection area and below the top
edge.
Preferably the tank extraction outlet or outlets and the tank inlet are
mounted at a top of the tank so as to allow the tank to be filled
substantially to the
top.
Preferably the tank extraction outlets include a first tank extraction
outlet in the liquid collection area mounted at an end of the tank remote from
the
discharge door and a second tank extraction outlet in the solids collection
area
mounted adjacent the discharge door.
Preferably the or each tank extraction outlet includes a float valve
comprising a float ball contained in a cage which is free to be floated
upwardly by
liquid to engage a valve seat to prevent passage of liquid into the duct to
the vacuum
pump and the valve seat is located in a receptacle for the float ball located
above a
top wall of the tank so as to allow the tank to be filled substantially to the
top wall.
Preferably the cage for the float ball is formed from row of chains.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
Figure 1 is a side elevational view of a vacuum truck according to the
present invention.
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Figure 2 is a cross sectional view longitudinally of the tank along the
lines 2-2 of Figure 1 showing the construction of the separation system within
the
tank.
Figure 3 is a ,cross sectional view transversely of the tank along the
lines 3-3 of Figure 1 showing the construction of the separation system within
the
tank and showing only a limited number of the chains for convenience of
illustration.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
DETAILED DESCRIPTION
The vacuum truck of Figure 1 comprises a truck frame 10 mounted on
ground wheels 11 and 12 for movement across the ground for transporting the
vacuum system from place to place for effecting excavation or extraction of
materials
13 from a location to be removed. The materials commonly include a quantity of
solids and liquid. Typically the vacuum truck is used to clear a blockage in a
drain or
culvert and hence it is necessary to remove both solid material 13 and liquid,
generally water 13A, surrounding or mixed with the solids.
The frame of the truck including a cab 14 and drive systems is entirely
conventional and therefore will not be described in detail herein. The truck
carries a
vacuum pump 15 again of a conventional nature of the type which generates a
high
level of vacuum and high air throughput. Such pumps are well-known and are
conventionally available and include a discharge duct 16 for disposal.
The system further includes a material storage tank and separation
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system generally indicated at 17 all of which are mounted as a common
structure on
rear hinges 18 adjacent the rear of the frame 10 so that the tank and
separation
system can be tilted about a horizontal axis defined by the hinges 18 by a
front lift
cylinder 19. Again the hinges and cylinder are of a conventional nature and
readily
available from various manufacturers. The lift cylinder can effect tilting of
the main
storage tank and separation system to a height sufficient to exceed the repose
angle
of the material stored within the tank so that it is readily discharged from
the tank
and from the filter system at the real of the tank and filter system.
The storage tank and separation system comprises a tank 20 which is
of circular cylindrical shape extending from a forward end 21 at the cylinder
19 to a
rearward end 22 at which is located a discharge door 23.
The vacuum system further includes an inlet hose 25 which has a rigid
front portion 24 mounted on a boom 27 for movement from place to place to
effect
lifting of the material 13. The hose 25 extends to an inlet opening 26 on the
top wall
of the tank 20 at a position generally mid-way along the length of the tank so
that air
carried along the hose 25 carries the material 13, 13A in suspension within
the
airflow until the air enters the storage tank 20 at the inlet opening 26 at
which time
the velocity in the air is dramatically decreased allowing the transported
material to
be discharged or dumped from the airflow and deposited in the base of the
storage
tank. In the embodiment shown the inlet merely discharges into the open tank
with
no cyclone or baffles so that the whole of the area underneath the inlet in
the top
wall is available for storage of the collected materials. However various
baffle
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arrangements or cyclones may be used within the storage tank to effect
extraction of
as much as possible of the particles and moisture from the air.
The air is drawn out of the storage tank through two outlets 28, 28A at
an outlet opening 29, 29A. A duct 40 communicates the extracted air from the
5 outlets 28, 28A to the vacuum pump 15. The extraction of solids and liquid
from the
air by simply discharging into the tank at the inlet 26 is generally
sufficient to remove
enough materials from the air to allow the air to pass through the vacuum
pump.
Turning now to Figures 2 and 3, the tank 20 includes a separation
system therein generally indicated at 32 for separating the materials
generally into a
10 liquid component and a solids component. The separation system 32 includes
a
generally upstanding dividing wall 33 across the tank dividing a solids
collection area
34 on one side from a liquid collection area 35 on the other side. The solids
collection area 35 is located adjacent the discharge door 23 so that the
materials
therein can be dumped with the tank is tilted. The tank inlet 26 is located in
the
solids collection area approximately at a mid point therealong in the top wall
so that
the vacuumed material including the water and solids is dropped into the
solids
collection area. The liquid collection area is smaller and reduced to a
minimum so
as to maximize the storage volume defined by the solids collection area.
A liquid pump 37 is mounted in the tank with the pump having an inlet
located in the liquid collection area for extracting the liquid component from
the tank
to increase a storage capacity of the tank for the solids component to be
collected
and transported in the tank on the truck to a remote location for discharge.
In the
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embodiment shown, the pump is a submersible pump located in the area 34 and
surrounded by a cage 36 to allow the extraction into the pump only of the
liquid
which is to be returned through an outlet pipe. However other types of pump
can be
used with the function of extracting the water from the area 34
The separation of the liquid or water from the solids is carried out
primarily by the dividing wall 33 which has a bottom wall portion 42, which is
substantially imperforate and has a top edge 43 at or adjacent a weir 45 over
which
liquid can flow into the liquid collection area. The bottom wall portion 42
has a
horizontal top edge and a semi-circular bottom edge matching the curvature of
the
tank so that the bottom wall portion substantially closes the tank below the
weir 45.
In the embodiment shown the top edge 43 is carried on a transverse rail 43A
which
provide structural strength. However the rail 43A may be omitted and the
portion 42
mounted on hinges at the sides with the top edge 43 defining the weir 45.
The dividing wall 33 has an upper screening section 46 above the weir,
which extends from the top edge to the top wall of the tank and is perforated
to allow
the liquid to pass over the weir 45 into the liquid collection area while
restricting
passage of the solids.
The upper screening section 46 includes a hanging curtain 47 covering
the whole of the upper part of the tank and formed by a series of side by side
lengths
of chain 48 which are connected to the tank only at a top end so that the
other end
of each length of chain is free and the length is suspended vertically with
the other
end of the lengths of chain in contact with or closely adjacent the top edge
43 of the
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bottom wall portion or the rail. Only some of the chains are shown for
convenience.
The upper screening section further includes a perforated screen support or
mesh
49 on the side of the curtain which is within the liquid collection area to
prevent the
curtain from being forced into the liquid collection area by the weight of
collection of
solids within the solids collection area.
The bottom wall portion is pivotally mounted on the rail 48 for pivotal
movement about a horizontal axis at or adjacent the top edge 43. Thus the
bottom
wall portion will pivot to the right as shown in Figure 2 in response to the
tilting of the
tank. The bottom wall portion reaches substantially to the bottom wall of the
tank so
that when it opens the tank is open underneath the rail 48 such that
substantially all
material at the bottom wall can discharge when the tank is tilted.
A stop 49 is provided to butt the left side of the portion 42 at the bottom
to prevent pivotal movement of the bottom wall portion to the left that is in
a direction
into the liquid collection area caused by weight of solids collected in the
solids
collection area and pressing against the bottom wall portion.
The liquid pump 37 has its inlet mounted in the liquid collection area
below the top edge so that the water falling over the weir collects in that
area and is
pumped out from the tank to the discharge at a suitable pipe 50 from which it
can be
returned to the area being cleared of the blockage. In this way only, or
primarily, the
solids are collected and removed.
The tank extraction outlets 28 and 28A and the tank inlet 26 are all
mounted at the top of the tank so as to allow the tank to be filled
substantially to the
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top. The first tank extraction outlet 28 is located at the front of the tank
in the liquid
collection area and the second tank extraction outlet 28A is located in the
solids
collection area. In this way the air continues to leave the tank even when the
tank is
filled at one end. In this way the diverging air from the inlet moving to the
two
extraction outlets acts to drop the materials from the air stream into the
tank acting
to load the solids collection area 35 relatively evenly thus maximizing the
amount of
material contained.
Each tank extraction outlet 28, 28A includes a float valve 52
comprising a float ball 53 contained in a cage 54 formed from row of chains
hanging
from the top of the tank. The ball is free to be floated upwardly by liquid in
the tank
when full to engage a valve seat 55 to prevent passage of liquid into the duct
to the
vacuum pump. The valve seat is located in a receptacle 56 for the float ball
53
located above the top wall of the tank and connected to the duct 28, 28A so as
to
allow the ball to float up above the top wall to the closed position thus
allowing the
tank to be filled substantially completely to the top wall.