Measuring and testing – Particle size
Patent
1999-05-26
2000-05-23
Raevis, Robert
Measuring and testing
Particle size
G01N 1502
Patent
active
060653566
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The invention comprises a method and apparatus for determining characteristics of a flowing particulate material.
BACKGROUND OF INVENTION
There are at least two previous,investigations aimed at utilizing naturally occurring periodic phenomena in powder flow for the characterisation of particulate systems. Budny, Thomas J., Powder Technology, (Lausanne), 23, 197 (1979) used a Table Model Instron to measure the fluctuations in the shear force when a powder bed was sheared. Stick-slip amplitudes were related to the flow rate from a powder dispensing device, but not to general flow properties. Kaye, Brian H., Gratton-Lumatainen, Julie and Neil Faddis, Part. Part. Syst. Charact., (Weinheim), 12, 232 (1995) correlated the avalanching behaviour of a powder contained in a rotating drum with fines content.
SUMMARY OF INVENTION
The present invention provides an improved or at least alternative method and apparatus for determining characteristics of a flowing particulate material.
In broad terms in one aspect the invention comprises a method for determining a characteristic or monitoring characteristics of a particulate material, comprising: as to maintain a substantially constant volume of flowing material in the measuring cell, and comparing oscillations in the weight of the contents of the measuring cell as the material flows through the measuring cell with reference information to determine said characteristic(s) of the flowing material.
Preferably said comparing is carried out by computing means and the reference information comprises stored comparative information in memory.
In broad terms in another aspect the invention comprises apparatus for determining a characteristic or characteristics of a particulate material, comprising: measuring cell to maintain a substantially constant volume of flowing material in the measuring cell and an outlet for exit of the flowing material, continuous indication of the weight of the contents of the cell, measuring cell with reference information in memory to determine said characteristic(s) of the flowing material.
Preferably the method comprises determining the type or constitution, surface characteristics, or general flowability of the particulate material by comparing oscillations in the weight of the contents of the measuring cell as the material flows through the measuring cell with said stored comparative information.
Preferably the method comprises determining the proportions of particles of different sizes or of different size ranges by comparing oscillations in the weight of the contents of the weighing cell with said stored comparative information.
Preferably the method comprises determining the proportions of particles of a smaller size relative to a balance of particles of a larger size in the flowing material by comparing to oscillations in the weight of the contents of the weighing cell to stored comparative information.
Preferably the method comprises determining the proportion of one type of material relative to a balance of one or more other types of material in the flowing material by comparing oscillations in the weight of the contents of the weighing cell to stored comparative information.
Preferably the weight fluctuations are analysed to produce frequency spectra or phase space data which is compared with stored data on various material types.
Other characteristics which may be monitored include the homogeneity of the material.
BRIEF DESCRIPTION OF FIGURES
The invention will be further described, by way of example and without intending to be limiting, with reference to the accompanying drawings, where:
FIG. 1 schematically shows one configuration of apparatus of the invention,
FIGS. 2a, 2b and 2c are plots of fluctuations in bulk density of batches of sand, wheat, and polypropylene pellets flowing through an experimental apparatus, over time,
FIGS. 3a, 3b and 3c are plots of the power spectra of the fluctuations in bulk density for the similar sand, wheat, polypropylene pellet batches,
FIG. 4 is a plot of the standard deviati
Industrial Research Limited
Raevis Robert
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