Rotary Kiln Combustion Gas Velocity Calculator

Calculate hot flue gas volumetric flow rate (actual m³/s and ACFM), axial gas velocity, and dust pickup entrainment limits in rotary kilns.

Combustion & Gas Flow

Combustion Flue Gas Q₀ (Nm³/h): At 0°C, 101.3 kPa standard

Average Gas Temperature T_gas (°C):

Internal Diameter D_inside (m):

Bed Filling Percentage (%):

Gas Velocity & Entrainment

Axial Gas Velocity (v_gas):

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Actual Gas Flow (Am³/s):

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Actual Volumetric Flow (ACFM):

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Thermal Expansion Ratio:

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Dust Pickup Velocity Assessment:

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Frequently Asked Questions

What is the optimal axial gas velocity inside a rotary kiln?

Industrial rotary kilns target an axial flue gas velocity between 4.5 m/s and 7.5 m/s. Velocities below 3.5 m/s reduce convective heat exchange; velocities above 8.5 m/s blow fine feed dust out of the kiln.

Why does volumetric gas flow rate increase so dramatically inside the kiln?

Gases expand proportionally with absolute temperature (Charles Law). Combustion gases at 1000°C (1273K) occupy 4.6 times more volume than at standard temperature (273K).

How does draft pressure control dust leakage?

Kiln draft fans maintain a slight negative pressure (-0.5 to -2.0 mbar) at the kiln hood and feed seal to prevent hot gases and abrasive mineral dust from blowing into the plant environment.