# Power Required to rotate a Kiln

1. Aug 27, 2011

### snehbiswas

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

2. Aug 27, 2011

### Unrest

Some factors to consider:

Acceleration - is it continuously rotating or stopping after each cycle?
Rolling resistance
Moment caused by off-center weight

3. Aug 27, 2011

### snehbiswas

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.

4. Aug 27, 2011

### Unrest

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?

5. Aug 28, 2011

### turbo

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.

6. Aug 28, 2011

### snehbiswas

Consider the rolling resitance coefficient to be 0.005. need help in designing a no-load condition rotating kiln.

7. Aug 28, 2011

### Unrest

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.