Digital temperature measurement system for industrial mixers

Nowadays, the mixing operation is one of the most common process in the consumer industry for the liquid products which involving physical and chemical change. Johnson & Johnson, one of the bigger multinational company active in this sector, uses this process on a large scale to produce its health consumer products - like creams and shampoos. Although much of knowledge on mixing has developed from chemical, food and pharmaceutical industries the components of the mixer are studied to optimize the time to reach the homogenization or in order to save power, but not to reach the homogenization temperature in the blending fluid. Indeed, in these processes the temperature is increased or decreased according to the raw material used to facility the blending and melting. In fact, some processes in Johnson & Johnson require up to 85°C. Consequently, this leads to incorporating a sensor that controls the heating system according to the temperature of the fluid. The sensor, that is currently used, is not able to track the entire temperature in the machine or to save the data for future studies. Meaning the sensor can only determine the temperature at its precise point in the machine and not the temperature in other points. The temperature of the fluid is not homogeneous due to the structure of heating system and the big dimensions of the tank. Some industrial mixer can produce up to 16 tons of products. Therefore, the purpose of this thesis is the design and develop a low power temperature measurement system that is able to collect the temperature of the fluid in multiple points inside the mixers. The system is developed and produced in the Johnson & Johnson consumer plant located in Pomezia. A possible wireless sensoring system in the fluid has been studied both to avoid the cables inside the mixer and to make it possible to integrate the system into environments that have specific requirements about compatibility with the chemical materials used during the mixer process. Unfortunately, the conductivity of the products does not allow for wireless communication with a range greater than 15 cm between the sensors. For this reason, the entire design integrates both wired and wireless communications and it is studied to respect the Good Manufacturing Procedure (GMP) requirements - including chemical and thermal compatibility. Each sensor is tested in laboratories and, through the Minitab tool, the results are collected to observe if they respect the requirements imposed by the company. After the realization of the system, it is tested in different conditions and in pilot mixing machine (the small reproduction of the industrial mixer). The initial studies are performed to observe the temperature gradients according to the speed of the propeller and impeller embedded in the mixer and to the blending fluid. Indeed, in the results, the viscosity and flow are observed as parameters which influence the homogenization of the temperature. Higher viscosity means higher temperature differences between the sensors, while turbulent flow homogenises the temperature faster than the laminar flow. In the future steps, the possible optimizations of the system are analysed to implement the system in the industrial mixers located in the plant.