For a rotary dryer, what is the typical cylindrical shell plate thickness used in practice (order-of-magnitude range)?

Introduction / Context:
Rotary dryers handle granular or particulate solids while rotating a slightly inclined steel shell. The shell thickness must withstand mechanical loads from rotation, support rings, and lifters, while resisting local wear and temperature-induced stresses.

Given Data / Assumptions:

• Medium-size industrial rotary dryer with standard operating temperatures.
• No extreme pressure differential; operation near atmospheric pressure.
• Carbon steel construction with typical wear allowances.

Concept / Approach:
Practical fabrication and structural requirements make ultra-thin shells (2–3 mm, 6–8 mm) unsuitable due to buckling and local denting risks. Excessively thick shells (18–22 mm or more) add cost and weight and are reserved for very large diameters or harsh mechanical conditions. Typical dryers fall in the mid-range, commonly around 12–15 mm.

Step-by-Step Solution:
Assess loads: dead weight, product holdup, riding rings, and drive.Consider temperature and wear: allow a corrosion/wear margin.Select practical plate thickness: 12–15 mm for common sizes.

Verification / Alternative check:
Vendor designs and industry references list shells in the low-teens of millimeters for standard dryers, increasing with diameter and duty severity.

Why Other Options Are Wrong:
2–8 mm: too thin for structural stiffness and durability.18–22 mm: heavier and costlier than needed for typical units.30–40 mm: reserved for unusual heavy-duty applications.

Common Pitfalls:
Ignoring local wear under lifters and at feed/discharge—liners may be needed.Not accounting for ovality from ring support spacing.

Final Answer:
12–15 mm