Optimización de sistema dosificador automático de aditivo alimentario comprimido empleando el método de elementos discretos (DEM)

Résumé

There are different methods of food additive dosage in the food industry, being the most widespread the one based on liquid form, which consisting in the spill of a water cascade bringing the additive dissolved. This method is an imprecise technique as far as dose accuracy is concerned, it usually provides spots due to the recirculation of the fluid and it is aggressive with the device mechanical parts while is not respectful with the environment. In this way, the automatic dosage of compressed additive arises as an alternative in tablet form. It is a precise, clean and effective dry-dossing method, since the tablets always have the same concentration of additive and does not generate any wasted part. This method complexity is found, on one hand, in the food additive mixtures compaction and in the own dossing due to achieve a continuously dosage respecting the tablets in its totality. For this reason, rises this PHD thesis, to optimize the design requirements of this device mainly are the achieving of a dosage rate threshold value in tablets per minute, and minimize the impact of tablet wear away. To do this, different configurations of operation of the device are studied, such as the variation of the inclination angle of the storage tank, which houses the tablets, and the rotation speed of the blades of the serialized output system, which generates a row of tablets for later place them in a packaging line of canned cans. In the development of this document and for the attainment of the targets lay out, DISCRETE ELEMENT METHOD (DEM) is used for the representation and simulation of the systems which form the dossing, considering it as a tool that reduces to particle level the solids to study its dynamics and it allows to understand like an ensembled complex system formed by the particles as distinct elements at the same time to know the movement and particle interaction. As the start point of the accomplished research, different models of food additive tablet, composed of salt, are obtained in the granular state by means of confined compression and different simulation batteries are made with various particle sizes to study the different parameters and physical variables that interact in the process. This process needs the simulation conditions are defined, as well as interactions between particles and contact models, to generate the necessary inter-particle bonds for its cohesion and develop a homogenous tablet. Furthermore, the forces involved in the process are analysed to determine the goodness of the models including the number of bonds that are generated as a function of the number of particles and its radius. Subsequently, these tablet models are included in the dosing device system mentioned for further analysis and validation. The effect of dossing velocity and tablet wearing is studied in harmony with the different models of generated tablet, being the target to see their behaviour, study the forces that suffer the particles and the speed of dosage that is reached, for determining which is the best one variables combination and tablet model chosen. Also, the geometry of the output blades is modified by testing several ways to try to identify which is the most respectful with the integrity of the tablets, maintaining the same criteria of dosage.