Rotating material feed for apparatus for pneumatic conveying of loose materials

An infeed device for transferring loose dry material from a hopper to an outlet from which the material is carried by pressure air, said infeed device comprising rotor means rotatable on a vertical axis and having circumferentially arranged material chambers that are open at their tops and bottoms, and said infeed device further comprising fixed structure on which said hopper is supported and which comprises vertically spaced horizontal plates between which said rotor means rotates and with which it has sealing engagement at its top and bottom, an upper one of said plates having therein a material inlet through which material falls from said hopper into material chambers that are brought beneath said inlet by rotor rotation, and said fixed structure having a pressure air inlet from which pressure air is blown downwardly through material chambers that are upwardly aligned with said outlet, for discharge of material into and beyond said outlet, said infeed device being characterized by:

• A. said rotor means comprising at least two rotors, one above the other, that are coaxial and are constrained to rotate in unison, said rotors having like numbers of material chambers so arranged that each material chamber in the upper rotor is coaxial with a material chamber in the rotor below it;
• B. said fixed structure comprising a plate between said upper rotor and the one therebeneath, in sealing engagement with those rotors, having a passage therein through which material can fall from chambers of the upper rotor into chambers of the rotor therebeneath, said passage being circumferentially spaced from said material inlet;
• and
• C. said upper rotor having pressure chambers therein which are closed at their tops and which have open bottoms that register with said passage as the upper rotor rotates, to receive pressure air from material chambers of said rotor therebeneath.