Kei Miyanami

A fuzzy control system of high shear granulation using image processing

Abstract A novel system has been developed to control granule growth in a high shear (speed) granulation. The system basically consisted of an image processing and a fuzzy control system. An image probe composed of a CCD camera, air purge unit and high energy xenon (Xe) lightning system was also developed to continuously take granule images through the sidewall of the vessel. The images were digitized by the image processing system and granule median diameter and shape factor were calculated automatically. Median diameter and shape factor of granules sampled out during granulation were also calculated by manually, and then compared with the automatically computed ones. Close agreement between both measurements was obtained, showing the developed system could continuously monitor granule growth during high shear granulation. A fuzzy control system using a linguistic algorithm employing if-then rules with a process lag element taken into consideration was developed to control granule growth accurately without any excessive growth (overshoot). This newly developed system was applied to actual high shear granulation of pharmaceutical powders and validity of the system was investigated. It was found that the system could control granule growth with high accuracy, regardless of changes in operating conditions.

Sound absorption measurements for evaluating dynamic physical properties of a powder bed

Abstract The normal incident sound absorption coefficient of a powder bed on a rigid plate has been measured in the frequency range of 200 Hz to 2000 Hz using an acoustic tube. Six different kinds of powder materials were used as samples; the mean particle diameter varied from 32.3 μm to 152.3 μm and the bed thickness varied from 10 mm to 40 mm. The sound absorption curves thus obtained had several distinct peaks; their frequency ratios were odd multiplications and the peak frequencies changed inversely with bed thickness. These peaks are attributable to the excitation of the normal vibration of the powder bed by sound wave incidence. Consequently, the sound absorption peak frequencies correspond to the natural frequencies of the powder bed. The measurements of vibration acceleration in the powder bed have clarified the fact that the primary sound absorption peak is related to the fundamental vibration mode, which is the one-end fixed longitudinal mode excited when one-fourth of the sound wavelength in the powder bed coincides with the bed thickness. These results show the possibility of estimating the dynamic physical properties of a powder bed, i.e. sound velocity and longitudinal elastic coefficient, from the primary sound absorption peak frequency of the powder bed. The measurements of the sound absorption coefficient by this method are hardly affected by powder vibration fluidization, etc., because they can be achieved in a non-contact state and in a short time, using a small vibrating force.

Dynamic measurements for the stiffness constant of a powder bed

Abstract A measuring apparatus was devised to determine the dynamic physical properties of a powder bed from the transfer function of vibration acceleration that results from the direct application of random vibration to the powder bed. By using this apparatus, the variation of the stiffness constant of a powder bed with various vibration forces and compression forces was measured. The stiffness constant gradually decreased when the vibration force exceeded a certain value. With respect to the change in stiffness constant with compression force, the following experimental equation was derived: k = SW n , where k is the stiffness constant of a powder bed, W the compression force applied to the powder bed, and S and n are empirical constants.

Application of a neural network to granulation scale-up

This paper describes a practical method for granulation scale-up by means of a neural network. Wet granulation was conducted using an agitation fluidized bed, and the scale-up characteristics were investigated using a neural network with back-propagation learning. Granule properties obtained by production-scale granulation under various operating conditions were predicted. Extremely good correlation was obtained between the predicted data and the experimental data of agitation fluidized bed granulation. It was found that granulation scale-up could be conducted with high accuracy by a neural network without constructing a mathematical model with a complicated non-linear relationship using a vast amount of experimental scale-up data.

Kneading and dispersion of positive electrode materials in a lithium ion secondary battery for high-density film

Focusing on the manufacturing process of the positive electrode of the lithium ion secondary battery, this research set out to investigate the kneading and dispersion that is required to distribute positive electrode particles of a high density within the film, and to investigate methods for evaluating the state of dispersion of the positive electrodes. We demonstrated that the dispersion of the positive electrode particles of the lithium ion secondary battery can be quantitatively evaluated by measuring the particle size distribution of positive electrode particles in the paste, the volume resistivity of the film, the film thickness, the film density and the glossiness, and by organically analyzing these measured values. Moreover, we revealed that, in order to manufacture high-density film, it is better to adopt the method of adding the binder in divided stages. In other words, we pointed out that in order to make positive electrode particles fill the film (plate) of a high density and to create good battery characteristics, the kneading and dispersion processes are extremely important. Furthermore, we were able to obtain a good correlation between volume resistivity and film density. In short, to produce a film that excels in battery properties, it is essential to increase the film density.

Optimization and validation of an image processing system in fluidized bed granulation

Abstract In a previous paper (Watano et al., Powder Technol. 83, 55–60 (1995)), we developed a particle image probe and an image processing system to continuously monitor granule growth in fluidized bed granulation. This paper describes optimization of the image processing system in agitation fluidized bed granulation. First, the effects of operating parameters of the image processing system (e.g. the sensor location and the number of particles analyzed) on the results of granule measurements were investigated experimentally, and the optimum operating parameters were determined. Secondly, the performance and validity of the optimized system were investigated under various liquid flow rates in actual agitation fluidized bed granulation. It was concluded that the optimized system could measure granule number median diameter and shape factor in fluidized bed granulation with high accuracy under various operating conditions.

IR absorption characteristics of an IR moisture sensor and mechanism of water transfer in fluidized bed granulation

Abstract Monitoring of moisture content by an infrared (IR) moisture sensor during fluidized bed granulation is a necessary way to control granule growth; however, this method requires prior investigation of IR absorption characteristics indicating the relationship between granule moisture content and IR absorption. In this contribution. for a better understanding of this IR absorption characteristics, fluidized bed granulation and drying were conducted at various powder samples and operating conditions with monitoring of moisture content by an IR moisture sensor. The effects of powder properties such as water absorbing potential and diameter on the IR absorption characteristics were investigated experimentally. Based on the results obtained, the water transfer mechanism among particles was analyzed, and factors which determined the IR absorption characteristic during fluidized bed granulation and drying were discussed.

Quantitative evaluation of kneading and extrusion processes by pressure transmission characteristics of wet kneaded masses

This study is devoted to the quantitative evaluation of wet kneaded masses prepared by a paddle-type kneader, and the analysis of the kneading process and the following extrusion granulation process. A compaction tester of wet kneaded masses has been developed and the compression properties of the masses are characterized by a pressure transmission between the upper and lower punches of the tester. The dispersion condition of a binder liquid among the wet kneaded masses prepared under various kneading times is investigated. The extrusion pressure through a single ejection hole on the lower punch is also measured. The pressure transmission is found to have a linear relationship between the dispersion of binder liquid and the extrusion pressure. This results lead to a conclusion that the proposed method provides the generalized measuring means of wet kneaded masses. An extrusion granulation by a dome-type extruder is conducted using wet kneaded masses and physical properties of the extruded pellets (granules), such as friability, specific surface area and disintegration time, are investigated. Good linearity can be found between the pressure transmission and the physical properties of the pellets. As the result of these findings, the kneading condition, i.e. the dispersion of binder liquid among the wet kneaded masses, can be quantitatively analyzed and the physical properties of pellets prepared by extrusion granulation can be accurately predicted by the pressure transmission measured by the newly developed compression tester.

Sound absorption by multi-layered constructions composed of powder layers and porous sheets

Sound absorption coefficients for powder beds comprised of fine powders (white carbon and vermiculite) were determined using a reverberation room. The characteristic curves showed high peaks in the low-frequency range, due to the excitation of longitudinal vibration modes in the powder beds by random incident sound. Multi-layered constructions composed of powder layers and porous sound-absorbing material (polyurethane foam sheets) were designed, and their sound absorption properties were investigated. Measurements showed that the multi-layered constructions have high sound absorption peaks in the low-frequency range, believed to be due to the combined effects of powder vibration and viscous dissipation in the pores of the polyurethane foam. The combination of two material possessing different sound absorption characteristics results in an expansion of the sound absorption frequency range and indicates the possibility of new sound absorbing materials for low-frequency sound. n n n nSound absorption simulation based on electric transmission line theory was applied to the multi-layered constructions. The calculated results agreed well with the measured results. A simulation using the propagation constant and characteristic impedance of the constituent materials was found to be useful in designing the frequency characteristics of these constructions.