rotary drum over hung

[mechmr]

hello,

originally the dimension of our rotary drum is 3m diameter x 6m length running at 25 tph

riding rings were installed 1m from the inlet and discharge.

after several running years, the length of the drum was increased to 7.5m (extending 1.5 meters from the discharge side) without modifying the original location of riding ring.

how to calculate over hung load on the drum?

what would be the new location of the riding rings for this new dimension?

thank you very much

(this is an edited post for it was posted on the wrong thread/activity)

 

[MFJewell]

maybe model it with internal pressure (load/sqft based on the process material) with external linear reaction loads where the rings are. You may be able to use some plate stress formulas from Roark's if you model it as a thin axial slice of the drum.

 

[hydtools]

Make a free body diagram and analyze it as a beam with a load distribution according to the distribution of the product being processed.

Ted

 

[dhengr]

Mechmr:
You have to describe your problem and process in much more detail if you want helpful answers. Some sketches; end views, side views and plan would be helpful, we can’t see it from here. What is the product being processed, what’s the process, what are the weights, loads, load distributions, etc? I’m thinking a kiln or drier of some sort. Originally, you had a 3m dia. by 6m long drum, running at 25 revs./hr. It had running rings at 1m and 5m on the drum length. In a gross fashion, that’s a simple beam with 1m cantilevers at each end, but you have to define the load distribution in much more detail. If you look at the inlet end view and the drum is rotating clockwise, I suspect the majority of the load is btwn. 5:30 and 8 o’clock in the drum (12 o’clock is at the top), so the rollers on that side are going to be more heavily loaded, and those loads/reactions are on the rollers and running rings. You will also have some sort of a continuous beam loading on the whole drum as a beam.

Now, you’ve added 1.5m of drum length to the discharge end of the drum, without moving the running rings. So, you have a 2.5m cantilever at the discharge end. You likely have more loading in the longer drum. This will significantly increase the roller loads at the discharge end, and particularly on the loaded side. That running ring should get a long hard look and may have to be made stronger, same with these two rollers. The increased length (and canti.) probably won’t cause big problems with the drum bending and gross stresses. But, the entire system should have a full engineering review. The rollers and running ring at the inlet end should probably be o.k., it actually should have a lighter loading now. The rollers and running ring at the discharge end probably have to be up-sized (strengthened) a bit, and might be moved .5m +/- toward the discharge end. Maybe leave the old running ring in place, you may do more damage trying to remove it than leaving it in place. And, stay away from the girth weld drum splice detail with the new running ring, that’s a fairly sensitive area too.

 

[mechmr]

hello,

thank you everyone for your response,

this rotary drum processes fertilizer material at 25 tons per hour.

right now i am still evaluating the load distribution on the drum

once again, thank you very much