Taking automatic control into wood ash recycling

Abstract

In Sweden, extensive research is conducted to find alternative sources of energy that should partly replace the electric power production from nuclear power. With the ambition to create a sustainable system for producing energy, the use of renewable energy is expected to grow further and biofuels are expected to account for a significant part of this increase. However, when biofuels are burned or gasified, ash appears as a by-product. In order to overcome the problems related to deposition in land fills, the idea is to transform the ashes into a product - agglomerates - that easily could be recycled back to the forest grounds; as a fertilizer, or as a tool to reduce the acidification in the forest soil at the spreading area. This paper introduces the general ash transformation concept and presents the necessary automatic control and signal processing needed to enable an automated manufacture of these agglomerates. However, as an alternative to using the most advance control theory, the paper also stresses that implementing a novel mechanical process design can heavily reduce the complexity of a specific control problem. Furthermore, along with some previously reported topics, new results regarding the delicate issues of wood ash agglomeration and agglomerate dehydration are presented.