Rotary vacuum drum filters – typical drum speed What is the normal rotational speed range of the drum in a rotary vacuum drum filter (RVDF), expressed in revolutions per minute (rpm)?

Introduction / Context:
Rotary vacuum drum filters are continuous filtration devices widely used for slurries. The drum rotates through zones of immersion, dewatering, washing, and cake discharge. Drum speed impacts cake thickness, residence time, and moisture content, and must be kept relatively low for effective vacuum filtration.

Given Data / Assumptions:

• Conventional RVDF with filtrate sectors and vacuum system.
• Moderate cake thickness and typical industrial slurries.
• Speed reported as rpm.

Concept / Approach:
Because filtration is rate-limited by permeability and vacuum differential, the drum rotates slowly to allow cake formation and dewatering. Typical speeds are fractions of an rpm up to about 2 rpm. Much higher speeds reduce residence time, yielding thin, wet cakes and poor washing. Lower speeds increase cake thickness but can reduce capacity and cause uneven discharge.

Step-by-Step Solution:

Verification / Alternative check:
OEM datasheets commonly list 0.1–1.0 rpm for heavy cakes and up to about 2 rpm for light, free-draining slurries.

Why Other Options Are Wrong:

• 3–8, 5–7, 8–15 rpm: Too fast for vacuum filtration residence times.

Common Pitfalls:
Confusing RVDF with rotary drum thickeners or rotary screens, which can run faster due to different mechanisms.

Final Answer:
0.1 to 2