Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to an apparatus for taking gas
samples from a container for bulk materials in dust or grain form.
Many forms of bulk materials, in particular materials in
dust form, are stored in closed containers. Such containers are
provided with a connection for filling the container with the
material and a material discharge arrangement which is frequently
in the form of a cell wheel-type flow control valve, i.e. a control
valve comprising a wheel rotatable mounted in a housing,
the wheel having a plurality of vanes or like means defining
cells or chambers which, for discharge of material from the
container, receive material as the wheel rotates, and transport the
material to an outlet from the housing. Such wheel-type valves are
particularly suitable for use on containers for containing material
in dust form or materials which are stored in an inert gas
atmosphere or under other special technical conditions. Besides
being used for storage purposes, such containers may also be
suitable for transporting the bulk materials.
Some bulk materials such as certain dusts, have a tendency to
spontaneous ignition but, before ignition actually occurs, they
usually generate gases which escape from the bulk material. On
the basis of the gases produced in that way, it is possible
for example to conclude that there is an impending danger of
fire. Still other bulk materials require the presence of an inert
gas atmosphere, as mentioned above, for storage purposes. In
that connection, it is necessary to ensure that the inert gas
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is always present in adequate amounts. Taking measurements in respect
of the gases which issue from the bulk material and which may
therefore indicate that there is a danger of fire, encounters
difficulties when the situation involves detecting those gases in the
lower region of the container or during the operation of emptying
-the container. Access to the lower part of the container is very
difficult so that hitherto that part of the container can be only
inadequately sensed by measuring probes. Another difficulty arises
because known measuring probes cannot be stationarily positioned
and left in place in the container so that they are therefore only
suitable for carrying out measuring operations which are severely
restricted in respect of time and place.
In accordance with -the present invention, there is provided
apparatus for -taking gas samples from bulk material in a container,
comprising a member for the discharge of material from the
container, a chamber outside the material discharge member, having
an opening providing a communication between the chamber and the
material discharge member and a sensor disposed in the chamber for
taking gas samples from material in the discharge member.
Accordingly, as will be seen in greater detail hereinafter,
a measuring sensor for measuring the presence of gases is
disposed outside the discharge member of the container in such a
way that the bulk materiels it issues from the container flows
past in the vicinity of the measuring sensor whereby the measuring
sensor is able to take gas samples continuously Fran the bulk
material flowing therapist. This arrangement has been found to be
particularly advantageous in use on bulk material containers for
storing dusts such as coal dust, as the gas which is produced in
the coal dust is discharged together with the dust and is sucked
in by the sensor which does not itself project into the flow of
bulk material, whereby the presence of critical gas components
can be satisfactorily detected while also ensuring that the
measuring sensor is not obstructed by the fine components of the
dust materials, so that in general it will remain operative
lo throughout the period for which measurements are to be taken.
Preferably, the chamber in which the measuring sensor is
disposed is arranged outside the outer wall of the casing which
delimits the cells of the cell wheel-type control valve
constituting the discharge control device of the container, and
the opening which communicates the cell wheel-type valve with the
chamber is provided in that outside wall. That arrangement can
ensure that the chamber with the measuring sensor is not itself
subjected to -the influence of the flow of bulk material which goes
therapist, but the gases, in respect of which the measurements are
to be taken, can flow freely and unimpededly into the interior
of the chamber.
Preferably and for that reason also, the measuring sensor is
disposed somewhat above or upstream of, as viewed in the
direction of -the discharge flow of the material, the connecting
opening between the wall of the cell wheel housing and the chamber
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in which the member is disposed, thereby ensuring that the flow
of bulk material cannot come into contact with the measuring
sensor itself, by virtue of the force of gravity acting on the
material. Advantageously, the action of that arrangement is further
assisted by a deflector plate in the chamber, which is inclined
downwardly towards the connecting opening between the cell
wheel type control valve and the measuring chamber and which
assists in preventing -the bulk material from penetrating into the
chamber and becoming deposited therein.
A preferred form of the measuring sensor, which has proved
successful, is a filter tube or hose arrangement essentially comprising
a pipe end portion which is bent over in a direction parallel
to the axis of the cell wheel of the control valve and which
is closed by a filter basket or strainer which is extended in
axial alignment with the pipe end portion.
An embodiment of the arrangement according to the present
invention will now be described by way of example with reference
to the accompanying drawings, in which:
Figure 1 shows a cross-sectional view of a section of an
arrangement for material discharge from a container, and
Figure 2 shows a view in cross-section taken along line II-II
in Figure 1.
The discharge arrangement of a bulk material container,
of which par-t is shown in cross-section in Figure 1, is a cell
wheel-type control valve 2 which comprises a cell wheel 14 which
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is mounted rotatable in a housing of the control valve 2 and
which is thus arranged to act as a connecting means between an
outlet connection or opening 15 through which bulk or loose material
in the container can flow therefrom, and an outlet 16 for final
discharge of the bulk material. The wheel 14 has radial blades
or vanes 17 which with the housing of the control valve 2, define
individual cells 13 which, when the wheel 14 rotates, convey the
bulk material in portions from the outlet connection 15
to the outlet 16.
An opening 18 is provided in the outside wall of the housing
of the control valve 2, which wall extends around the periphery
of the cell wheel 14~ The opening 18 extends substantially
uninterruptedly over the entire axial width of the wheel 14. Pro-
voided in the region of the opening 18 in -the wall of the housing
of the control valve 2 and on the outside of -the housing wall
is a chamber 11 defined by a flange 19 and closed by a removable
cover 3. Seals 4 (Figure 2) are provided between the flange
19 and the cover 3, so as to seal off from the exterior the chamber
11 which is formed within the flange 19.
The cover 3 is provided on its inward side with a projection
portion 21 which, as shown in Figure 1, fits inside the flange 19
and which, at its end which is inwardly of the chamber 11, carries
a wall portion 9 so positioned as to constitute an extension
of the wall of the housing of the control valve 2. The wall portion
9 partially closes off the opening 18 in the wall of the housing
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of the control valve 2, leaving an opening 12 by way of which the
interior of the chamber 11 communicates with the interior of the
housing of the valve and thus selectively with the cells 13. The
wall portion 9 is of such a dimension that a cell 13 which is
positioned in that region is closed over its periphery between the
outlet connection 15 and the chamber opening 12 with sufficient over-
lap to ensure that the bulk material cannot shoot through from the
container directly into the measuring chamber 11.
Disposed adjoining the lower edge of the opening 12, as shown
in Figure 1, is a deflector plate 8 which projects upwardly into
the chamber 11 at an inclined angle of about 70 and the upper
edge of which, at the cover 3, is above the level of the upper
edge of the opening 12. The plate 8 divides the chamber 11 into two
spaces which are each approximately triangular in cross-section.
Disposed in the substantially triangular space above the plate
8 is a measuring sensor 1 indicated generally by reference numeral 1
in Figure 2. The measuring sensor 1 comprises a suction pipe 10 which
is connected to a suitable suction source and which extends with
an extension portion through an opening in the cover 3, into the
chamber 11. The extension portion is bent over through a right
angle to face in a direction parallel to the axis of the cell
wheel I and carries a filter member or strainer in the form
of an elongate filter hose 1 which extends at a right angle relative
to the suction pipe 10 and which thus extends longitudinally
through the chamber 11 in a direction at least substantially
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parallel to the axis of the cell wheel 14. The filter hose 1 extends
substantially over the major part of the axial length of the
chamber 11.
Outside the cover 3, the suction pipe 10 is mounted on a
vibrator 7 which in turn is secured -to a bracket-like extension
portion 20 on the cover 3. The suction pipe 10 is taken through
the cover 3 in such a way that the vibrations imparted to the
suction pipe 10 by the vibrator 7 are not impeded and at the same
time the chamber 11 is maintained in a sealed condition.
Arranging the filter hose 1 in -the upper part of the chamber 11,
that is to say above the opening 12, and the presence of the deflector
plate 8, ensure that bulk material cannot reach the filter hose 1.
Operation of the cell wheel control valve 2 is not adversely
affected by the provision of the chamber 11. Portions of bulk
material which penetrate into the chamber 11 through the opening
12 are deflected out of the chamber again by the deflector plate
8, by virtue of the inclined position thereof. That ensures that
bulk material which is being transported by the cell wheel 14
does not accumulate within the chamber 11 so that fresh bulk
material is constantly being supplied to and taken past the
measuring sensor 1. The filter hose 1 is subjected to a
reduced pressure by way of the suction pipe 10, whereby gases can be
sucked out of the bulk material and fed to a measuring means (no-t
shown) by way of the suction pipe 10. The measuring means then
analyses the gases present in the bulk material, and the composition
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of such gases, that analysis providing information about the
condition of the bulk material or the inverting phase thereof.
Instead of the filter hose 1 being cleaned by shaking by means
of the vibrator- 7, as provided in the illustrated arrangement,
the future hose 1 can also be cleaned in other ways, for example
pneumatically, by being subjected to a flow of gas or air in
the opposite direction, by way of the suction pipe 10. The cleaning
operation can be carried out by means of the vibrator in a
continuous mode, that is to say, even during the measuring operation,
or it may also be carried out pneumatically by means of air or
inert gas after each measuring process, or the filter hose may
be cleaned by being knocked to remove any dust clinging to it.
The vibrator 7 thus ensures that any fine particles of dust
which are deposited on the filter pipe 1, particularly when
measuring bulk materials in dust form, are continuously shaken off
so that the filter hose 1 does not become clogged.
It will be seen therefore that the above-described measuring
arrangement can remain constantly in its position of operation for
detecting the presence of gases in the bulk or loose material in the
lower region of the container or during emptying of the container,
and is capable of supplying measurement values continuously over
a prolonged period of time.
Various modifications may be made in the above-described
embodiment without thereby departing from the scope of the
invention as defined by the appended claims.
