From boiler (left) to conditioner for pelleting: Steam is a costly and valuable ‘ingredient’ and its measurable characteristics directly affect product quality, efficiency of pelleting, and overall economy of production.
Good steam: Better
conditioning and pelleting
Proper steam conditioning can lead the way to
improved pellet quality, extended equipment life,
and reduced energy cost in production.
By Yiqiang Xiong, PhD, and Keith Behnke, PhD
Formulation, ingredients, and grinding play
very important roles in pellet durability
and overall pellet quality. In the pellet operation itself, however, feed mash conditioning
is likely to be the lead factor affecting pellet
quality. For mash conditioning, the supply
and quality of steam amount to an ‘essential
ingredient’—not only for improving pellet
quality, but also for lowering production costs
and protecting product nutrient value. Recent
studies even suggest that proper adjustment
of the conditioning steam system can double
or triple pellet die life.
Conventional or unpressurised feed
mash conditioning using steam is a process
of heat exchange and moisture condensation which effectively softens mash particles.
It also may hydrate functional proteins, such
as gluten, and possibly gelatinise starch.
These effects allow the mash particles to
compress tightly and adhere to each other
when passing through the pellet die. Good
steam conditioning thus improves pellet
durability index (PDI) and reduces fines.
Moreover, it also reduces electricity and
maintenance cost of the pelleting operation,
increases production rate, and minimises
