PALE POUR DISPOSITIF MELANGEUR

A BLADE FOR A MIXING DEVICE

Abrégé français

La présente invention concerne une pale destinée à un dispositif mélangeur, notamment un appareil mélangeant différentes particules ou différents liquides, laquelle pale se monte sur des rotors sensiblement horizontaux. Chaque pale est caractérisée par une première face présentant une incurvation orientée dans le sens de déplacement des particules. Dans le sens radial, la forme des pales présente des lignes droites disposées perpendiculairement à l'axe du rotor. La pale incurvée est constituée d'une première partie (3) orientée dans le sens de déplacement des masses, d'une deuxième partie (4) sensiblement plus petite, orientée dans le sens inverse du déplacement, et d'une partie intermédiaire reliant les deux premières parties précitées et disposée sensiblement parallèlement à l'axe du rotor. Cette structure permet de propulser, d'une part vers l'avant une partie substantielle de masses, tandis qu'une moindre partie subit une centrifugation, et d'autre part vers l'arrière, les particules venant ainsi se mélanger aux particules propulsées vers l'avant à partir de la pale suivante.

Abrégé anglais

A blade for a mixing device, especially for the mixing of different
particles or different liquids, where the blade is mounted on a substantially
horizontal
rotor and extends in a straight line perpendicular to the rotor axis. The
blade has a
curved cross-section with a front part or first portion facing in the
direction of motion of
the particles or liquids in the mixing device, a substantially smaller rear
part or second
portion facing opposite the direction of motion, and a part lying in between
and
connecting the front and rear parts and substantially parallel to the rotor,
axis; such
that a substantial portion of the particles or liquids are thrown forwards,
and smaller
portions are thrown directly outwards and backwards, the particles or liquids
thereby
being mixed with particles or liquids thrown forward by a following blade.

Revendications

5
CLAIMS:
1. A blade for a mixing device for the mixing of different substances, the
blade adapted to being mounted on a rotor having a substantially horizontal
rotational
axis and a direction of rotation, and the mixing device having a direction of
motion of
the substances being mixed parallel to the rotor axis, the blade when mounted
on the
rotor extending in a straight line perpendicular to the axis of the rotor, the
blade
having a cross-section which is curved with a first portion facing in the
direction of
motion of the substances, a second substantially smaller portion facing
opposite the
direction of motion of the substances, and a portion lying between and
connecting the
first and second portions and being substantially parallel with the rotor
axis, whereby
when the rotor with such blade is rotated, a substantial portion of the
substances
being mixed are thrown in the direction of motion and smaller portions are
thrown
directly radially outwards and opposite to the direction of motion.
2. A blade according to claim 1 where the blade has an axial length
along the axis of the rotor and has a first end adapted to being mounted on
the rotor
and a second end remote from the axis of the rotor, where the second end
comprises
a flange which creates an obtuse angle with the blade and extends
substantially along
the entire axial length of the blade.

Description

CA 02180136 2004-12-07
BLADE FOR A MIXING DEVICE
FIELD OF THE INVENTION
The present invention relates to a blade for a mixing device, where the
blade is arranged on a substantially horizontal rotor.
BACKGROUND
Mixing devices are used within a number of fields for mixing two or more
different substances, such as particles or liquids or a combination of these,
to a
desired degree of homogeneity. The different substances are supplied in
amounts
which are metered to a specified degree. Such substances may be two or more
liquids to be mixed, two or more particles, or particles to be added and mixed
with
liquids. The substances to be mixed have greater or smaller differences in
nature and
condition.
Such mixing devices are also used for drying or freezing particles either
as separate processes or as part of a mixing process.
Mixing devices of this type normally operate with blades or shovels
secured to two parallel rotors, rotating in opposite directions. The shape and
arrangement of the blades causes the substances to be mixed to be thrown
upwards
so as to be mixed and simultaneously transported forward in the mixing device.
It is
important that the so-called casting curvature of the blades (that is, the
upper
boundary of the path followed by substances thrown upwards by the blades) is
optimized to achieve the best possible mixing together with the desired
forward
transportation.
Flat blades arranged in different positions along the rotor axis are well
known; and there have long been attempts made to change the angle of the
blades in
relation to the rotor axis and other parameters such as the rotation rate, the
length of

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CA 02180136 2004-12-07
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the blades, etc. to optimize the mixing process.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a blade for a
mixing device for the mixing of different substances, the blade adapted to
being
mounted on a rotor having a substantially horizontal rotational axis and a
direction of
rotation, and the mixing device having a direction of motion of the substances
being
mixed parallel to the rotor axis, the blade when mounted on the rotor
extending in a
straight line perpendicular to the axis of the rotor, the blade having a cross-
section
which is curved with a first portion facing in the direction of motion of the
substances,
a second substantially smaller portion facing opposite the direction of motion
of the
substances, and a portion lying between and connecting the first and second
portions
and being substantially parallel with the rotor axis, whereby when the rotor
with such
blade is rotated, a substantial portion of the substances being mixed are
thrown in the
direction of motion and smaller portions are thrown directly radially outwards
and
opposite to the direction of motion.
It has now been found that altering the shape of the blades may further
optimize the mixing process, and result in other advantages.
These advantages are achieved with blades according to the present
invention as defined in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Some embodiments of the invention will now be described in
conjunction with the accompanying drawings in which:
FIG. 1 is an axial schematic view of a mixing device having two rotors.
FIG. 2 is a view looking down a blade according to this invention toward
the rotor axis.

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CA 02180136 2004-12-07
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FIG. 3 is a corresponding view of an alternative blade form.
DETAILED DESCRIPTION
FIG. 1 is an axial schematic view of a mixing device shown generally at
having a container 11 and two rotors 12 and 12', rotating in opposite
directions as
5 shown by the arrows, with axes shown by the crosses. Blades 1 and 1' are
shown
secured to rotors 12 and 12' respectively.
As shown in FIG. 1, the end of the blade remote from the rotor axis 12 is
suitably bent upward to form a flange 2 or a flange 2 is secured to the blade,
either as
a continuous curvature or at an obtuse angle to the blade. The flange 2 points
in the
10 direction of motion of the substances being mixed and extends substantially
along the
axial length of the blade.
Substances which are thrown radially outward along the blade 1 hit the
flange 2 and thereby change their path. It is important that a substance
thrown radially
along the blade 1 will mostly hit the flange 2 and thereby change its
direction instead
of hitting the bottom of the container 11 of the mixing device; as this means
that the
wear on the bottom of the container is decreased, which is of substantial
importance
depending on the substances being mixed.
As shown in FIG. 1, it is important to have a blade with a curved cross-
section to achieve a substantial distribution of the substances being mixed
and an
optimized high casting curvature 5.
FIG. 2 is a view looking down a first embodiment of a blade 1 according
to this invention toward the axis of the rotor 12 to which the blade is
secured. In this
embodiment the blade 1 is formed as part of a pipe having a circular tubular
cross-
section. The pipe may conveniently be divided into four segments, each of
90°, so that the cross-section of the blade is a 90° circular
arc. Each

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CA 02180136 2004-12-07
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segment, which forms a blade, is secured to the rotor axis as shown in FIG. 2,
with
the segment turned an angle .alpha. in relation to the rotor axis. A suitable
angle
.alpha. is about 20°; resulting in the cross-section of the blade
having a larger
first portion or front part 3, a smaller second portion or rear part 4, and a
part 6 lying
between and connecting the front part 3 and rear part 4 and being
substantially
parallel to the axis of the rotor 12. By this arrangement, part of the
substances to be
mixed are influenced by the front part 3 of the blade, and are transported
forwards in
the transportation direction of the mixing device (shown by the arrow), and
another
part are influenced by the rear part 4 of the blade and are transported
backwards in a
direction opposite to the transportation direction of the mixing device. The
curved form
of the blade 1 thus provides a substantial dispersal of the substances being
thrown up
by the blade; with substances thrown backwards being mixed with substances
thrown
forwards by a following blade.
FIG. 3 is a view looking down a second embodiment of a blade 1 of this
invention towards the rotor axis 12. In this embodiment, the cross-section of
the blade
is not a circular arc, but is a curved surface having a front part 3, a rear
part 4, and a
part 6 lying between and connecting the front part 3 and rear part 4. The
transportation direction of the mixing device is indicated by the arrow. In
this
embodiment, the rear part 4 of the blade still provides a greater distribution
of the
substances being mixed, causing a portion to have no movement parallel to the
rotor
axis in the transportation direction of the mixing device and a portion to be
moved in a
direction opposite to the transportation direction of the mixing device.

Dessin représentatif