... materials: sawdust, rice shell, kinds of crops straw, shell. Production steps: Crush (sawdust no need) - drying - rods - ... packaging, finished process.4. Product advantage: (1) large boiling drying chamber volume, Long stroke (stretched length), ... double insulation and special refractories production, thickness of 30mm, long service life.(3) large diameter, pipe wall thickness, and durability. ( ...