Preconditioner having mixer shafts independently driven with variable frequency drives

A processing system, comprising:

• a processing device presenting a processing chamber with an inlet and an outlet;
• a preconditioner comprising
• an elongated mixing vessel having a material inlet and a material outlet and configured to receive a material to be processed including a plurality of different ingredients, said preconditioner outlet operably coupled with said chamber inlet;
• apparatus operable to deliver moisture into said mixing vessel during processing of said material;
• a pair of elongated mixing shafts each having a plurality of elongated, outwardly extending mixing elements, said shafts located in laterally spaced apart relationship within said vessel with the elements of each shaft being intercalated with the elements of the other shaft, said elements oriented to avoid any collision between the elements during rotation of said shafts;
• a pair of variable drive mechanisms respectively coupled with said shafts in order to permit selective rotation of the shafts at individual rotational speeds independent of each other and to allow high-speed adjustment of said rotational speeds of said shafts without collision between said mixing elements;
• and
• a controller operably coupled with said drive mechanisms to independently control the rotational speed of said shafts.

A method of preconditioning a material comprising the steps of:

• providing a preconditioner including an elongated mixing vessel having a material inlet and a material outlet, a pair of elongated mixing shafts, each of said shafts having a plurality of elongated, outwardly extending mixing elements thereon and located in laterally spaced apart relationship within said vessel, with the elements of each shaft being intercalated with the elements of the other shaft, said elements oriented to avoid any collision between the elements during rotation of said shafts;
• directing a quantity of said material including a plurality of different ingredients into said vessel through said inlet, and introducing moisture into the vessel to mix with said material;
• and
• selectively rotating said shafts at respective rotational speeds independent of each other in order to precondition said material and move the material toward and out said vessel outlet, without collision between said mixing elements.