Calculation for grain falling through a pipe

[tmoo]

I am trying to calculate the necessary diameter (or cross sectional area) of a pipe to yeild a known flow rate for dispensing grain. Could anyone give me any pointers?

 

[davefitz]

The procedure for sising these pipes was presented in texts by Zenz, and there are a few articles in the magazine Chemical Engineering that also discuss this.

The air velocity has to exceed the particle's "saltation velocity" or its terminal falling velocity. If the particle has a size distribution or if all particles are a defined size then different calculation procedures are used.

Simplified maesures to calculate the required velocity use Stokes flow relationships , but these are only accurate at low rehynolds numbers.

 

[Maui]

Try contacting the people at this website:

http://www.senkbilefarms.com/dmc.htm

They should be able to point you in the right direction.


Maui

 

[Kiwi98j]

To calculate spout size in US bushels/square inch of area for sheet metal, free falling grain, (corn, soybeans, wheat rapeseed), use 90. If spout is choke loaded, use 70 bus/sq in as amximum flow rate. If spout is other than 90 degrees off horizontal, use 60 bus/sq in if angle is greater than 5 degrees plus the angle of repose for the grain you are dealing with. 40 degrees is the angle of repose for grains listed above.