Amélioration de l’autonomie énergétique et de l’impact environnemental d’une unité de trituration de tournesol par l’implantation conjointe d’un atelier de décorticage et d’une chaudière à coques

Abstract

Fibre rich sunflower hulls have always been regarded as having a remarkable calorific value (5 000 kWh/t DM), very close to that of wood. Rising energy costs, emergent environmental concerns, and fitness for use of sunflower derived products have led to a growing interest in the dehulling of sunflower seeds prior to crushing, and burning of hulls in biomass boilers to yield process steam on site. This was made possible by prominent technological improvements in boiler technology. The torsional chamber technology exhibits good performances in full combustion of sunflower hulls, allowing for a high efficiency, a great flexibility, and a limited emission of pollutants. Yet, fumes may still have to be post-treated to ensure compliance with stringent restrictions in dust emissions. Being a robust and versatile technology, the torsional chamber is able to cope with a feedstock quality varying to a certain extent. The general design of a crushing plant fitted with a dehulling unit is impacted dramatically and becomes very sensitive to variations in hullability of the incoming seeds. Hull content and size of the seeds are correlated positively to hullability; moisture, density and oil content being correlated negatively. Hullability is affected mostly by environmental effects, cultivars being responsible for it to a lesser extent. Thus, hullability is impacted by upstream practices in plant breeding, field, and grain elevator management. Success in an efficient hulling strategy not only depends on the use of relevant technologies on processing plants, but also relies on knowledge of the seed and meal customer needs, as well as on concerted actions at various levels along the sunflower chain.