Twin screw pump grinder

Abstract

A screw conveyor, for the transport of flowable substances and/or lumps of material, includes a rotatable first screw provided with helical windings arranged in a housing with an inlet opening and an outlet opening. The housing includes an inlet chamber and a pumping chamber between the openings. In at least in the pumping chamber there is a second screw provided with helical windings and arranged for rotation in the opposite direction of the first screw, the screws in the pumping chamber providing a positive displacement pumping function by mutual engagement. Also provided is a cutting device downstream of the pumping chamber and housed within a knife house including an internal channel, where the knife house is connected to the outlet opening. By providing the knife house with second outlet, overfilling of the knife house is prevented. As an alternative means for varying the internal volume of the knife house may be used.

1 . Screw conveyor for the transport of flowable substances and/or lumps of material, comprising: 
 a rotatable first screw provided with helical windings arranged in a housing with an inlet opening and an outlet opening, said housing including an inlet chamber and a pumping chamber between said inlet and outlet openings;    at least in the pumping chamber, a second screw provided with helical windings and arranged for rotation in an opposite direction of the first screw, said first and second screws in said pumping chamber providing a positive displacement pumping function by mutual engagement between the first and second screws when said rotatable first screw is rotated in a first sense of rotation;    a cutting device downstream of the pumping chamber and housed within a knife house, said cutting device including an internal channel, where said knife house is connected to said outlet opening;    wherein said knife house is provided with second outlet means for receiving at least a portion of said substances and/or materials provided to the knife house from said pumping chamber; and    wherein said second outlet means are located upstream of the cutting device avoid overfilling of the pumping chamber.    
   
   
       2 . Screw conveyor according to  claim 1 , wherein said second outlet means comprises a passage leading from said knife house to a controllable buffer valve which upon activation is able to accommodate said portion of substance and/or material and upon a subsequent activation is able to supply said substance and/or material back to the knife house.  
   
   
       3 . Screw conveyor according to  claim 1 , wherein said second outlet means comprises a passage from said knife house back to said inlet chamber in which said passage there is a controllable valve.  
   
   
       4 . Screw conveyor according to  claim 1 , wherein said second outlet means are being provided by reversing the direction of rotation of said first and second screws whereby at least a portion of said substance and/or material present in the knife house is removed from the knife house via said screws.  
   
   
       5 . Screw conveyor according to  claim 1 , wherein said means for varying the volume of said internal channel comprises a piston that can be displaced out of/into said channel by means of an actuator.