Measurement of rice flow: Influence of grain shape on the flow

1. Introduction

GranuFlow is an semi-automatised instrument which allows measuring rapidly with a high accuracy the flow of a powder through holes of different diameters. This instrument is able to give to you in a few seconds important information on the flowability of your granular material. GranuFlow is equipped with a rotating plate pierced with 8 holes.  You can chose between two plates with different hole diameters (small holes from 4 to 18mm or large holes from 20 to 34mm hole diameters). With GranuFlow, your are able, by using the rotating plate, to find easily the minimum hole diameter to ensure the suitable flow of your powder.

You can also measure the flowability of all your batches in order to control and to optimize your process or to compare your products during an innovation phase. With GranuFlow, you can make fast and large number of analyses using a non-destructive test. So, your are able to control your product every time, after production, for the storage and before the delivery to guarantee to your customers  high quality products.


2. Experiment: influence of the grain shape on the flowability of rices

For making this study, three kind of rices have been selected: Gallo Risotti, Bosto Thai and Bosto Wok. For each kind of rice, we have measured the major a and the minor b axes of the grain by using a classical office scanner and an image analysis software. Elongation parameter (a/b) is then calculated from a and b axes. Table 1 gives the main geometrical parameters of the different rices. Hole diameter of the GranuFall used in this study is 18mm. Experiment time of the flow is about 1 minute by sample.

Table 1: Geometrical parameters of the studied rices


Figure 1 shows the evolution of the flow in function of the elongation parameter for each rice. Standard deviation has been calculated based on 3 experiments. We can observe a strong correlation between the elongation parameter and flow measured with GranuFlow instrument. Flowability decreases with elongation parameter. So, Gallo Risotti with the nearest spherical shape (a/b = 2.2) is characterized by the best flowability. GranuFlow instrument can be used to easily measure the flowability of the different rices and also to classify the different samples.

Figure 1: Bulk flow versus the elongation parameter for different rices – grain rice shape effect on the bulk flow

3. Conclusions

 These experiments show that GranuFlow instrument can be easily used for measuring the bulk flow of macroscopic grains such as rice. Inversely, you can thus classify the different rices depending on their shape only by measuring their flow properties. In addition, this example clearly shows the influence of the grain shape on the bulk flow of macroscopic grains.