GRANULAR MATERIAL"

TECHNICAL FIELD The present disclosure relates to a field of measuring instruments. Particularly, but not exclusively, the disclosure relates to rheology measuring instrument. Further, embodiments of the disclosure disclose a device for determining rheological properties of granular material.

BACKGROUND

In process industries, such as mineral processing, food, pharmaceuticals, and petroleum refining, large volumes of particulate materials or granular materials are being handled, processed and modified in continuous flow operations. Physical characteristics of the granular materials such as particle size, shape, size distribution, and hardness may affect the flow properties. Hence, measurement and interpretation of rheological properties of the granular materials, also termed as powders, such as sand, food grains, cosmetics, pharmaceuticals, paints, coatings, cement, and the like may be one of the paramount interest in the preparation and use of such materials in several process industries. The measurement or determination of the rheological properties of granular materials has been a major challenge, because the flow of these materials is far more complex than that of fluids.

Some devices have been developed and used in the art, for determination of rheological properties of the granular materials. The existing devices may be characterized under two broad categories. One category of devices measures the yield strength, or the conditions of stress under which a static assembly of grains undergoes plastic yield. These devices may be largely used in the fields of civil and geological engineering, where strains beyond a few percent may be considered as catastrophic. On the other hand, devices in the second category may determine the stress during continuous shear, generated typically by moving a rigid surface against a powder. One such device may provide a crude measure of flowability of particulates, by creating a complex flow of particles in the granular materials. This, makes inference of the rheology difficult, hence it does not measure a material property that is geometry-independent. Though efforts have been made in some of the conventional devices to create simple flow and closely resemble fluid rheometers, but they too do not measure the true material properties because they do not measure the kinematics. In addition, most of the conventional devices may fluidize the powders by passing air through the powder vertically upwards, and assume the state of stress to be uniform along the vertical direction. Moreover, the properties determined by such devices are likely to depend on the extent of fluidization. Therefore, the rheological properties measured by conventional devices may not be accurate. All existing devices in both categories mentioned above make only a few gross measurements, such as the force or torque and normal force on a moving boundary.

The present disclosure is directed to overcome one or more of the limitations stated above or any other limitations associated with the conventional arts.

SUMMARY OF THE DISCLOSURE

One or more shortcomings of the prior art are overcome by a device as claimed and additional advantages are provided through the provision of device as claimed in the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the present disclosure, a device for determining rheological properties of a granular material is disclosed. The device comprises a hollow outer cylinder, and an inner cylinder rotatably disposed in the hollow outer cylinder. The configuration of the inner cylinder and the hollow outer cylinder defines an annular gap between an inner circumference of the hollow outer cylinder and an outer circumference of the inner cylinder for accommodating the granular material. The inner cylinder is rotatable at a one or more pre-set speeds shearing the granular material. A plurality of first sensors is mounted on an outer circumference of the inner cylinder, to generate signals corresponding to the rheological properties of the granular material.

In an embodiment, the hollow outer cylinder is stationary with respect to the inner cylinder. Further, the inner cylinder is disposed coaxially in the hollow outer cylinder, and is supported on a base enclosing one end of the hollow outer cylinder.

In an embodiment, the inner cylinder comprises a flanged extension extending outwardly along a rotational axis of the inner cylinder. In an embodiment, the device comprises a rotary actuator coupled to a flanged extension for rotating the inner cylinder. In an embodiment, the inner cylinder comprises a plurality of provisions extending from an inner circumference to the outer circumference for accommodating the plurality of first sensors, the plurality of provisions extends along a length of the inner cylinder.

In an embodiment, the device comprises a slider slidably disposed on the outer circumference of the hollow outer cylinder, wherein the slider is movable upward and downward along a length of the hollow outer cylinder.

In an embodiment, the device comprises one or more second sensors mounted on the slider. The upward and downward movement of the slider is configured to carry the sensing surfaces of the one or more second sensors to any position along depth of the granular material.

In an embodiment, the plurality of first sensors and one or more second sensors are multi-axis force sensors, configured to measure three components of the forces acting on the sensing surfaces to generate signals corresponding to the stresses developed in the granular material. These stresses may be used to determine the rheological properties of the granular material. Further, the plurality of first sensors and the one or more second sensors are associated with a wireless transmitter for transmitting the signals to a wireless receiving unit.

In an embodiment, the device comprises an image capturing unit facing the annular gap for capturing images of the granular material, when the inner cylinder is rotated.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristics of the disclosure are explained herein. The embodiments of the disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawing in which: FIG.l illustrates a perspective view of a device for determining rheological properties of granular material, in accordance with an embodiment of the present disclosure.

FIG. 2 illustrates a perspective view of the device of FIG. 1, showing an arrangement of a motor and an image capturing unit, in accordance with an exemplary embodiment of the disclosure.

FIG. 3 illustrates a perspective view of an inner cylinder of the device of FIG.2, in accordance with an exemplary embodiment of the present disclosure.

FIG. 4 illustrates exploded perspective view of the inner cylinder of the device of FIG.3.

FIG. 5 illustrates a front view of an inner cylinder of the device of FIG.3, in accordance with another exemplary embodiment of the present disclosure.

FIG. 6a illustrates a schematic top view of the device of FIG. 1, showing rotation of the inner cylinder within the hollow outer cylinder.

FIG. 6b illustrates a schematic front view of the device of FIG. 1, showing the inner cylinder within the hollow outer cylinder with plate. FIG. 7 illustrates a graph of variation of the azimuthal velocity with distance from the inner cylinder of the device of FIG. 6.

FIG. 8 illustrates a graph of variation of the radial velocity with distance from the inner cylinder of the device of FIG. 6. The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the description. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

Embodiments of the disclosure disclose a device for determining rheological properties of granular material also termed powders such as sand, food grains, cosmetics, pharmaceuticals, paints, coatings, cement, and the like may. The device may be configured to determine all three components of surface traction of the granular material as a function of the depth using sensors, and the velocity field may be determined by video imaging the upper surface. The simultaneous measurement or determination of the stress and the kinematics make the determination more straightforward to infer the functional relation between the stress and strain rate of the granular material.

The device according to embodiments of the disclosure may comprise a hollow outer cylinder which is configured to be stationary, and an inner cylinder disposed in the hollow outer cylinder. The configuration of the inner cylinder in the hollow outer cylinder defines an annular gap in which a granular material to be tested may be filled. The inner cylinder may be rotated at a preset constant or time-varying speeds which shears the granular material in the annular gap. The device also includes a plurality of sensors which includes first sensors mounted on an outer circumference of the inner cylinder, and one or more second sensors mounted on a slider slidably disposed on an outer circumference of the outer cylinder. The plurality of first sensors and the one or more second sensors are configured to measure all three components of the forces acting on the granular materials, and generate a signal corresponding to the rheological properties of the granular material. The plurality of first sensors and the one or more second sensors may be associated with a transmission unit such as but not limiting to a wireless transmitter for transmitting the signal. The signal or data received by the wireless transmitter may correspond to the forces measured by the plurality of first sensors and the one or more second sensors. The plurality of first sensors and the one or more second sensors measures the three forces applied on its surface. This may be converted to stresses. The stresses may be used to calculate the rheological properties, such as friction coefficient, and yield stress of the granular material.

In an embodiment, the device may also be configured to measure velocity field during shearing of the granular material. To measure the velocity field, the device may be employed with an image capturing unit which may be oriented towards the annular gap. The image capturing unit may be configured to continuously take the images or record the video of the annular gap to determine the kinematic of flow.

Reference will now be made to the exemplary embodiments of the disclosure, as illustrated in the accompanying drawings. Where ever possible same numerals will be used to refer to the same or like parts. The following paragraphs describe the present disclosure with reference to Figures 1 to 8. In the foregoing description words such as top, bottom, upward, downward, and the like are used with respect to particular orientation of the figures illustrated. However, the same may vary with the variation in the orientation of the figures.

FIGS. 1 and 2 are exemplary embodiments of the disclosure illustrating perspective view a device for measuring rheological properties of materials such as granular materials. The granular materials may also be referred as powders, and such materials may include but not limiting to sand, food grains, pharmaceuticals, mineral ores, coatings, cement, and the like. The device (100) as shown in FIG. 1 comprises a coaxial cylinder assembly including a hollow outer cylinder (101) [interchangeably referred to as outer cylinder], and an inner cylinder (102). The hollow outer cylinder (101) may be configured as stationary cylinder, and the inner cylinder

(102) may be rotatably disposed in the hollow outer cylinder (101). In an embodiment of the disclosure, a bottom side of the outer cylinder (101) comprises a base (101c) defined with at least one provision [not shown] for accommodating a shaft extending from the inner cylinder (102). Such that the inner cylinder (102) may rotate freely inside the outer cylinder (101). In an embodiment, the shaft may be supported on the base through one or more bearings [not shown] . Further, the configuration of the inner cylinder (102) inside the outer cylinder (101) defines an annular gap (103) [shown in FIG. 2] between the inner circumference (101a) of the outer cylinder (101) and an outer circumference (102a) of the inner cylinder (102). The annular gap

(103) may be configured to accommodate the granular material (G) to be tested for rheological properties. The inner cylinder (102) may have a shaft fixed to an upper end through a flanged extension (113) extending upwardly along the rotational axis (A-A) of the inner cylinder (102). The shaft (102a) may be coupled to a rotary actuator (112) through a suitable mechanism including but not limiting to belt drive, chain drive and gear drive mechanism. In an embodiment, the rotary actuator may be at least one of a motor, hydraulic or pneumatic actuator. The rotary actuator (112) may be operated at pre-set constant or time-varying speeds, to rotate the inner cylinder

(102) inside the outer cylinder (101). The rotation of the inner cylinder (102) will apply shear forces on the granular material (G) disposed in the annular gap (103).

The device (100) also includes an image capturing unit (111) such as but not limiting to a camera with a lens arrangement as shown in FIG.2. The image capturing unit (111) may be arranged in the device (100) such that the lens of the image capturing unit (111) face towards the annular gap

(103) . In an embodiment, the image capturing unit (111) is a high-speed video camera mounted above the cylinders such that a section of annulus may be imaged by the camera. The video images obtained may be analyzed using a particle image velocimetry software to obtain the azimuthal and radial velocity profiles to determine kinematics of the granular material (G) in the annular gap (103), when the inner cylinder (102) is rotated. As shown in FIGS. 1 and 2, the device also includes a slider (106) configured on the outer cylinder (101). The slider (106) may accommodate one or more second sensors (107b), such that a sensing surface of the one or more second sensors (107b) and slider (106) are mounted to flush against the outer cylinder (101). The slider (106) may be translated along a vertical direction on an outer circumference (101b) of the outer cylinder (101), such that sensing portion of the one or more second sensors (107b) may be moved to any location along the depth of the granular material (G) in the annular gap (103). In an embodiment, the slider (106) may be operated in vertical upward and downward direction on the outer cylinder (101) using a suitable mechanism including but not limiting to rack and pinion mechanism, linear actuators and the like. In an embodiment, a plurality of the sliders (106) may be configured along the circumference of the outer cylinder (101). The configuration of the one or more second sensors (107) on the slider (106) may measure all three components stress acting on the sensing surface corresponding to the stress on the granular material (G) such as radial normal stress and the two shear stresses. In an embodiment, the hollow outer cylinder (101) may be defined with an opening in the form of a key way or a slot to accommodate the slider (106). The slider (106) may be configured with cross section corresponding to the cross section of the opening, such that the slider (106) is held in transition relationship with the outer cylinder (101).

Now referring to FIGS. 3 and 4 which are exemplary embodiments of the present disclosure illustrating a perspective view and exploded view of the inner cylinder (102) of the device (100). The inner cylinder (102) comprises a cylindrical body enclosed by flanged extensions (113) on either ends. One of the flanged extension (113) may be coupled to the rotary actuator (112) for rotating the inner cylinder (102) in the outer cylinder (101). As shown in FIG. 3, the inner cylinder (102) may have a plurality of provisions (104) extending from the inner circumference (102b) to the outer circumference (102a) of the inner cylinder (102). The plurality of provisions (104) may accommodate a plurality of first sensors (107a). In an embodiment, the plurality of provisions (104) may be provided on a portion of the inner cylinder (102) arranged one below the other from upper end to the lower end. In another embodiment, the plurality of provisions (104) may be provided in any position on the circumference of the inner cylinder (102).

In an exemplary embodiment, the plurality of provisions (104) may be configured on a strip (S) mountable on at least a portion of the inner cylinder (102) as shown in FIG. 4. The strip (S) may configured to slide fit with the inner cylinder (102), such that the strip (S) forms a part of the inner cylinder (102) in the assembled condition. In an embodiment of the disclosure, the plurality of first sensors (107a) may be disposed in any one of the plurality of provisions (104) configured at different heights. The provisions (104) without the sensors (107a) may be closed with blanks (108) that are flush mounted against the inner cylinder (102).

In an embodiment of the disclosure, the plurality of first sensors (107a) mounted on the inner cylinder (102), and the one or more second sensors (107b) mounted on the slider (106) may be multi-axis force sensors. The plurality of first sensors (107a) and the one or more second sensors (107b) may be associated with a wireless transmitter [not shown]. The wireless transmitter may transmit the signals generated by the plurality of first sensors (107 a) and the one or more second sensors (107b) wirelessly to the receiving unit [not shown]. In an embodiment, the wireless transmitter may be physically connected to the plurality of first sensors (107) and the one or more second sensors (107b). The data or signal received by wireless receiving unit correspond to the forces measured by the plurality of first sensors (107) and the one or more second sensors (107b). The plurality of first sensors (107) and the one or more second sensors (107b) may measure forced applied on its surfaces. As an example, plurality of first sensors (107) and the one or more second sensors (107b) may measure all three forces such radial normal forces and the two shear forces applied on its surface. These forces may be converted to stresses. The stresses may be used to calculate the rheological properties, such as friction coefficient, and yield stress of the granular material.

Reference is now made to FIG. 5 which is an exemplary embodiment of the disclosure illustrating a front view of the inner cylinder (12) used in the device (100). The inner cylinder (102) may be configured with a plurality of grooves (105) extending on the outer circumference (102a). The plurality of grooves (105) may enhance the secondary flow of the granular material, and thus enhance shear of the granular materials such as cohesive powders. In an embodiment, the plurality of grooves (105) may helical grooves extending throughout the length of the inner cylinder (102). In another embodiment, the plurality of grooves (105) may be clockwise over a part of the cylinder height, and anti-clockwise for another part, so as to create a squeezing flow between the two parts. Such an arrangement may serve to analyze the type of flows arising in practical applications. In an embodiment of the disclosure, a method for operating the device (100) for determining rheological properties of the granular material (G) is disclosed. The method comprises firstly filling of the granular material to be studied in the annular gap (103) between the inner and outer cylinders (101 and 102). The granular material (G) may be pretreated according to a set protocol. Then, the granular material (G) may be sheared by rotating the inner cylinder (102) at a preset constant or time-varying speed. When needed, a floating plate (114) of fixed weight can be placed over the annulus to provide a confining stress on the upper surface of the granular material.

During the process of shearing, the stress may be generated in the granular material (G) due to the rotation of the inner cylinder (102). These stresses may be measured at the outer and inner cylinders (101 and 102). For measuring the stress on outer cylinder (101), the slider (106) on the outer cylinder (101) may be translated along the vertical direction i.e. upward or downward direction, such that one or more second sensors (107b) may be moved to any location along the depth of the granular bed. During the movement, the one or more second sensors (107b) may generate signals corresponding to all three components of the forces such as radial normal stress and the two shear stresses in the outer periphery of the granular material (G). Further, the plurality of first sensors (107) on the inner cylinder (102) may generate signals corresponding to all three components of the forces such as radial normal stress and the two shear stresses in the inner periphery of the granular material (G). The plurality of first sensors (107) and the one or more second sensors (107b) may be associated with a transmitter, which transmits the signals via a wireless communication channel. Also, the kinematics of the flow may be measured using the high-speed video camera (111) mounted above the inner and outer cylinders (101 and 102) such that a section of the annulus is imaged. The video images obtained may be analyzed using a particle image velocimetry software to obtain the azimuthal and radial velocity profiles. The simultaneous measurement of the stress and the kinematics using the device (100) makes the measurement of rheological properties of granular material a more direct measurement than what is made in existing devices.

FIGS. 6a and 6b are an exemplary embodiments of the disclosure illustrates a schematic top view and front of the device (100) showing rotation of the inner cylinder (102) within the hollow outer cylinder (101) with out and without plate respectively. The inner cylinder (102) is rotated with the help of rotary actuator (112) inside the hollow outer cylinder (101), shearing the granular material (G) filled in the annular gap (103). The arrow marked with 'r' indicates the radial velocity direction, and the arrow marked with 'θ' indicates the azimuthal (rotational) velocity direction in the device (100). The speed of movement of the particles of the granular material (G) may be measured both in the radial direction and azimuthal directions, and graphs of FIGS. 7 and 8 are generated. The plate (114) shown in the FIG. 6b may introduced at required level for applying load on the granular material bed. FIG. 7 is a graph showing variation of the azimuthal velocity with respect to distance from the inner cylinder (102). The graph illustrates the variation azimuthal velocity without any load (curve-A) on the granular material and with load (curve-B) on the granular material (G). From, the graph it can be seen that, variation of the velocity with distance is an indication of the magnitude of the shear rate. This information may be used to infer the rheological properties of the granular material being tested. Further, the FIG. 8 shows a graph of variation of radial velocity with respect to distance without any load (curve-A) on the granular material (G) and with load (curve-B) on the granular material. The radial velocity indicates the presence or absence a secondary flow in the granular material (G). The strength and variation of the radial velocity with distance from the inner cylinder (102) may provide an indication of the flowability of the granular material (G). As can be seen from the graphs FIGS. 7 and 8, there is no qualitative change on the flow of the granular material (G) with addition of the load on the granular material (G) bed. This provides an indication, that the device (100) provides accurate information or results in various operating conditions. In an embodiment of the disclosure, the device (100) is simple in construction and accurately determines the rheological properties of the granular material (G).

It is to be understood that a person of ordinary skill in the art may develop a device of similar configuration without deviating from the scope of the present disclosure. In one such modification, the outer cylinder may be made rotatable with respect the inner cylinder, while maintain the inner cylinder stationary. Such modifications and variations may be made without departing from the scope of the present disclosure. Therefore, it is intended that the present disclosure covers such modifications and variations provided they come within the ambit of the appended claims and their equivalents.

Equivalents:

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

List of reference Numerals

105 Grooves in inner cylinder

106 Slider

107a Plurality of first Sensors

107b One or more second sensors

108 Blanks

109 Wireless transmitter

110 Floating plate

111 Image capturing unit

112 Rotary actuator

113 Flanged extension

114 Plate

S Strips

G Granular material

A-A Rotational axis of the inner cylinder