Multiple moving wall dry coal extrusion pump

1. A pump for transporting particulate material comprising:

a passageway defined at least partially on all sides between an inlet and an outlet by at least two moving walls spaced apart from each other such that essentially an entire perimeter of said passageway is movable; wherein no portion of said at least two moving walls contacts another portion of said at least two moving walls.

2. The pump as recited in claim 1 , wherein said passageway is generally polygonal in cross-section.

3. The pump as recited in claim 1 , wherein said passageway is generally round in cross-section.

4. The pump as recited in claim 1 , wherein said passageway is defined by four moving walls.

5. The pump as recited in claim 1 , wherein said passageway is defined by two driven moving walls and two idler moving walls driven by said two driven walls.

6. The pump as recited in claim 1 , wherein said passageway defines a L/W Ratio greater than 3.

7. The pump as recited in claim 1 , wherein said at least two moving walls each include no more than one portion defining said passageway, and said portion is completely planar.

8. The pump as recited in claim 1 , wherein said at least two moving walls are driven separately from each other.

9. A particulate material transporting pump, comprising:

a first movable wall providing a perimeter side of a generally polygonal passageway;

a second movable wall providing another perimeter side of said passageway; and

a third movable wall providing another perimeter side of said passageway, wherein said first, second, and third movable walls are separate from each other, wherein said first, second, and third movable walls are movable independently from each other.

10. The pump as recited in claim 9 , wherein said first, second, and third movable walls each include portions that provide said perimeter sides, and said portions are entirely planar.

11. The pump as recited in claim 9 , including a fourth moving wall, wherein said third and fourth movable walls are driven by said first and second moving walls, respectively.

12. The pump as recited in claim 9 , wherein said passageway defines a L/W ratio of greater than 3.

13. A particulate material transporting pump, comprising:

a first movable wall providing a perimeter side of a generally polygonal passageway;

a second movable wall providing another perimeter side of said passageway, wherein said perimeter side provided by said first movable wall is aligned with said perimeter side provided by said second movable wall;

a third movable wall providing another perimeter side of said passageway; and

a fourth movable wall providing another perimeter side of said passageway, wherein said perimeter side provided by said third movable wall is aligned with said perimeter side provided by said fourth movable wall,

wherein said perimeter sides of said first, second, third, and fourth movable walls are disconnected from each other.