CONTROL AND SUPERVISION FOR AN INDUSTRIAL GRAIN DRYER Clemente Cárdenas, Eduardo J. Moya, David García and Oscar Calvo Fundación CARTIF, Parque Tecnológico de Boecillo. Parcela 205. 47151 Boecillo, Valladolid, Spain Keywords: Supervision, Control, Industrial Process, PLC, SCADA, Profibus, PID. Abstract: Automation and control of processes in a food industry is a very important aim. The main reasons are: guaranteeing a better quality of the final product, reducing cost time and improving the use of the raw materials. Specifically, drying and storage grain industries have plants which, in many cases, are out of phase. Besides, they are controlled by machine operators. Our work has consisted in developing a total and supervision automated system to control most of the processes. A first step has been to automate four cereal dryers in order to collect data. Subsequently, a control has been designed to get a constant value of moisture of the grain. At the same time, these data have been used to obtain a total traceability of the process. 1 INTRODUCTION In most cereal drying industries it is very important to store the final product in optimal conditions along time in order to achieve a good preservation. Combination of several measures is necessary: • Grain cleaning and sorting, avoiding any undesired product or seed. • Drying until a moisture level is reached, to guarantee the correct preservation. • Storing temperature Control during all the time that the product remains in the facilities. In general, once recollected, grains don’t have a suitable degree of humidity and temperature to be stored in silos for a long period of time. That is why it is necessary to increase the temperature in order to reduce humidity, making the drying a process of great relevance. Therefore, supervision and automation offer the operator the necessary tools to control the drying process accurately, using historical and real-time process performance information. Improving control enhances consistency and saves energy by ensuring key process variables are more stable. Processes may also be operated closer to optimum values or constraints. Process automation is not innovative, but if supervision and control solutions are customized, as in this case, we can deduce, then, that we are innovating. In the following sections we describe an example of control of such processes. 2 DRYING AND STORAGE PROCESSES Basically, the cereal drying process consists in passing a hot air current through the product, in order to reduce the moisture inside the grain. There are several factors to take into account from the point of view of the process and also from that of the product: • The product can have different humidity percentages. • Moisture reduction depends on each type of grain. • Each product has a temperature upper limit and a humidity lower limit to consider . • The goal is to achieve a maximum performance in Tons/hour, as well as a minimum energetic consumption. A horizontal grain dryer consists of a perforated metal sheet connected to a source of heated forced air supplied by a diesel or gas burner. The grain conduit has upper and lower ends to receive and discharge, respectively, a quantity of grain to be dried by heat conveyed to the grain through the perforated sheet. Rollers with an agitator keep grain moving downward into the dryer. It is also necessary 405 Cárdenas C., Moya E., García D. and Calvo O. (2009). CONTROL AND SUPERVISION FOR AN INDUSTRIAL GRAIN DRYER. In Proceedings of the 6th International Conference on Informatics in Control, Automation and Robotics - Robotics and Automation, pages 405-408 DOI: 10.5220/0002192904050408 Copyright c  SciTePress