Product Overview The WLS420×8500 sludge dryer feed screw conveyor is a shaftless screw conveyor (WLS series) purpose-built as the feed stage of sludge drying lines. It receives dewatered sludge from filter equipment and delivers it continuously at a controlled rate into the inlet of a low-temperature sludge dryer. Installed at a -20° downward incline , the unit moves material downward under both gravity and screw thrust, forming a steady feed stream that prevents wet cake