Power Required to rotate a Kiln

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Discussion Overview

The discussion focuses on calculating the power required to rotate a horizontal kiln, considering various factors such as mass, dimensions, speed, and resistance. The scope includes technical calculations and considerations related to the design and operation of the kiln.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant requests assistance in calculating the power required for a kiln with specific mass, dimensions, and speed.
  • Another participant suggests considering factors like acceleration, rolling resistance, and moments caused by off-center weight.
  • A participant claims that rolling resistance and moments from off-center weight can be considered negligible for continuous rotation.
  • Another participant challenges the idea that no power is required, questioning the implications of starting and stopping the kiln.
  • One participant notes the historical context of rotating kilns and emphasizes that off-center loads are significant for energy requirements during operation.
  • A participant introduces a rolling resistance coefficient of 0.005 and seeks help in designing a no-load condition for the kiln.
  • Another participant agrees that rolling resistance may be the primary power loss but cautions about the potential impact of off-center mass, suggesting it should be checked.

Areas of Agreement / Disagreement

Participants express differing views on the significance of rolling resistance and off-center weight, with some considering them negligible while others argue they are important factors. The discussion remains unresolved regarding the exact power requirements and the impact of various factors.

Contextual Notes

There are limitations regarding assumptions about the kiln's operation, such as whether it is continuously rotating or stopping, and the potential impact of off-center weight and rolling resistance on power calculations.

snehbiswas
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Can anyone help me out in calculating the power required to rotate a Horizontal Kiln resting on Rollers of following data:

Kiln Mass 60000 kg
Kiln Length 35 m
Kiln Diameter 2.8 m
Roller Diameter 0.8 m
Radial distance between two centers 1.992m
Kiln Shell Thickness 0.025 m
Speed 4 rpm
Time 180 sec
 
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Some factors to consider:

Acceleration - is it continuously rotating or stopping after each cycle?
Rolling resistance
Moment caused by off-center weight
 
The kiln shell is rotating continuously with tyres resting on support rollers. Rolling resistnace and momnet caused by off-center weight can be considered negligible.
 
snehbiswas said:
The kiln shell is rotating continuously with tyres resting on support rollers. Rolling resistnace and momnet caused by off-center weight can be considered negligible.

That suggests it requires no power! What non-negligible reasons would you have for driving it instead of just letting it spin freely?

Starting and stopping would be significant. Is that what you're concerned with?
 
Rotating kilns for calcining lime, etc, have been around forever. Why not see how they are specced WRT drive capabilities? Off-center materials load is definitely NOT negligible, btw. That is the reason that you have a rotating kiln to mix the feed material, expose it to the heat, and transport it and discharge it at the product end. That all takes energy. The kiln does not rotate freely if it is in production.
 
Consider the rolling resitance coefficient to be 0.005. need help in designing a no-load condition rotating kiln.
 
snehbiswas said:
Consider the rolling resitance coefficient to be 0.005. need help in designing a no-load condition rotating kiln.

So rolling resistance is the only loss of power? That's (more) realistic. But you might also want to consider the inevitable off-center mass present in the kiln itself. That may be negligible, and may depend on tolerances, but you should check just in case.

For rolling resistance, see Wikipedia

For startup, use torque = rotational inertia * angular acceleration.
 

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