Songling's screw conveyor uses a rotating helical screw blade within U-trough, to move ash or other bulk materials and often used horizontally or at a slight incline.
The screw conveyor consists of a trough containing a spiral blade coiled around a shaft, driven at one end and held at the other, or a
"shaft less spiral", driven at one end and free at the other.
The sizing of screw conveyor depends on the rate at which it is to be handled and physical characteristics of the material such as particle size and distribution, flow ability, abrasive quality and moisture content etc. The rate of volume transfer is proporticnal to the rotation rate of the shaft.