3.6.2.2  Conditioning

Conditioning can be defined as “any modification  or addition made to the mash after it leaves the mixer and before it reaches the pellet die chamber”. One has to consider that pellet quality is primarily established in the conditioner, not in the pellet die.

Conditioning   is   the   most   critical   step   to manufacture quality  pellets. Regardless of conditioning technique used, the fundamentals are the same: heat and moisture are added to the dry meal. Conditioned meal is then readied for plasticization during the pelleting process. The moisture is critical for the ease of passage of the meal through the die, and for proper agglomeration. Heat energy is critical for uniform transportation of moisture  to the centre of the meal particles. Conditioning can improve pellet quality and reduce the amount of energy required to pellet. Proper conditioning of the meal prior to physical agglomeration also facilitates the pelleting process.

Atmospheric conditioners are fairly simple in the design, essentially being mixing vessels with steam and liquid ports. However, several criteria that are essential to the proper operation and maintenance of conditioner are:

•         Effective steam hardness (quality & heat content)

•         Proper steam pressure

•         Correct pick configuration

•         Retention time

The most critical aspect of conditioning involves regulation of steam. Typically this is accomplished through  the  use of  steam hardness. It  is  essential that  good  steam has the right  quantity  of  heat to  optimize the migration  of  moisture  into  the interior  of  the meal particles. Unfortunately, good quality pellets cannot be achieved by maximizing the conditioning temperature alone, but also by understanding the critical factors that influence steam quality  and conditioner  performance. These factors include good,  clean steam, a firm grasp on mixed meal, moisture & temperature and, proper steam pressure adjustment capability.