Piovan has debuted a new line of auto-adaptive multiple hopper drying systems delivering optimal and consistent operating conditions and lower energy consumption, for which a first patent has been issued in Europe.
The ancillaries equipment maker says in developing the new Modula, it has incorporated process control elements in addition to these bonus features (high operating reliability, energy and efficiency). These include consistency in the physical characteristics of the polymer after drying and the system is adapted automatically to the initial conditions of the polymer and those required by the process.
Piovan says there are many variables in the drying process and all have been taken into account in the Modula project, launched in 2010 and now offered in a new range of systems. It can adapt and automatically control operating parameters based on ambient temperature, initial moisture level, type and quantity of polymer, the final moisture content of the polymer, and granule size. In the case of applications that involve a number of materials of different kinds, a central unit is commonly used to generate dry air, which is then distributed to a series of hoppers, one for each material. Each hopper requires specific conditions for optimum operation (air flow, temperature and pressure) depending on the different process variables.
A safety condition is systematically adopted and the drying system is sized based on the most critical processing parameters, at maximum material consumption, at maximum temperature, with the highest airflow. However, this goes against any principle of energy efficiency and raises running costs, as these extreme conditions rarely occur. Instead, Modula software adjusts and controls optimal operating settings for each hopper using only the overall amount of energy strictly required. The settings are constantly compared with the data collected by the sensors installed on the system. A patented measuring unit, located in the air supply line at each hopper, adjusts and controls the air flow instantaneously and independently. The total airflow is modulated automatically by the central drying unit, resulting in optimum process operating conditions. This way, a medium capacity Modula system (drying 200-250kg/h of polymer) provides savings of as much as 50% with respect to traditional central drying systems of equivalent capacity.
Piovan says Modula is the only central drying system capable of calculating exactly how much material, for each type, is used by the moulders and adjusts the operating parameters accordingly. In addition to maintaining a constant dew-point, Modula adjusts the airflow to the quantity of material effectively used, regulating the thermal load for each kilogramme of polymer processed.
The control system of Modula is provided with an algorithm which varies the quantity of air supplied to each individual hopper, circulating the air content required to keep the thermal load constant. Maximum operating efficiency is achieved when the entire thermal energy in the hopper is transferred to the material. The air returning from the hopper to the dryer therefore does not require cooling water in order to ensure system operation and absorption by the aluminum silicate molecular sieves.
The new Modula configuration features an air generation unit that connects to up to 16 hoppers. The unit can be set up to operate in parallel to guarantee absolute operating consistency. In this instance, the two generation units always work in partial load mode to maximise the energy efficiency of the inverter-controlled, IE3 class process blowers. Each hopper has an independent heating chamber to control the polymer temperature and a measuring system for the air flow designed and patented by Piovan.