Can someone help me figure out how much torque I need

[Rodrigrows Org]

Hello I am new to site and need some help building a big mixer similar to picture the problem i have run into is i need to know what size motor and gear reducer box i need for this application i need to find out how much torque it takes to spin the paddle wheel when fully loaded the the weight of my material is 10,500 lbs my paddle is 5 ft in diameter 14 feet long and I need this to spin at 15-20 rpm can anyone help me with equation for this thanks. http://www.robinrents.com/stow-paddles.jpg

 

[CWatters]

Is there anything similar you can compare it with? Such as a concrete mixer? Otherwise I suspect you might have to make a series of smaller prototypes to scale, measure the torque and power required and extrapolate.

 

[billy_joule]

With mixing being such a key process in industry I'd guess there's been considerable research done, have you checked unit operation textbooks?

 

[CWatters]

There must be a lot of variables.. viscosity, size and shape of the paddle, clearance between paddle and container..

http://en.wikipedia.org/wiki/Mixing_(process_engineering )

Many of the equations used for determining the output of mixers are empirically derived, or contain empirically-derived constants. Since mixers operate in the turbulent regime, many of the equations are approximations that are considered acceptable for most engineering purposes.

It goes on to reference the "North American Mixing Forum sponsored Handbook of Industrial Mixing".

 

[MullaTheMech]

And 2.5ft instead of the 7ft i wrote

 

[Rodrigrows Org]

And 2.5ft instead of the 7ft i wrote

Yes your picture is exactly what I am trying to build.

 

[Rodrigrows Org]

With mixing being such a key process in industry I'd guess there's been considerable research done, have you checked unit operation textbooks?

yes i have the problem is no one make a mixer in the size I am making its either much smaller or much bigger.

 

[MullaTheMech]

I am a complete newbie who makes tons of mistakes. someone check my work!

at a 1:1 gear ratio you need a motor with a1137 watt output or 50,000ft*lbs
at a 1:2 ratio you need 567 watts or 25000ft*lbs
I don't know how to incorporate the rpm in this formula.

 

[MullaTheMech]

http://en.wikipedia.org/wiki/Gear_ratio
This should help