wobbling agit. shaft due to vortex in tank
wobbling agit. shaft due to vortex in tank
(OP)
What do you call the wobbling effect on an agitator shaft caused by a vortex in a mixing vessel?
Roy Gariepy
Maintenance and Reliability Dept.
Dorlastan Fibers LLC.
Goose Creek, South Carolina USA





RE: wobbling agit. shaft due to vortex in tank
You need to install side mounted baffle plates, add a bottom support/bearing to the agitator, change blade design, or slow the agitator down.
There are several other things you might be able to do but these are the most common.
You have got to stop the wobble in the shaft.
A quick visit by a tech rep for agitator drive could be of some value.
RE: wobbling agit. shaft due to vortex in tank
Roy Gariepy
Maintenance and Reliability Dept.
Dorlastan Fibers LLC.
Goose Creek, South Carolina USA
RE: wobbling agit. shaft due to vortex in tank
I suggest you to check the design fluid parameters(density and viscosity) for any abnormal deviation.
Secondly check for shaft inclination.
Regards,
RE: wobbling agit. shaft due to vortex in tank
We had 2 instances that I was involved in with a similar problem where the bottom hub on top supported agitator was bent. This caused the blades to be skewed which in turn caused a vibration and shaking as you describe. The problem was corrected by straightening the mounting hub to restore the correct pitch and angle of attack of the blades.
The second one was more involved. Besides straightening the hub the blades were modified by drilling one or two holes in the blade.
Both these agitators were center mounted and top supported.
Come back ith a few more details of your setup.
RE: wobbling agit. shaft due to vortex in tank
Kind regards,
Roy Gariepy
Maintenance and Reliability Dept.
Dorlastan Fibers LLC.
Goose Creek, South Carolina USA
RE: wobbling agit. shaft due to vortex in tank
RE: wobbling agit. shaft due to vortex in tank
RE: wobbling agit. shaft due to vortex in tank
Normally if the mixer is mounted off-center it needs to be inclined so it faces into the direction of the swirl/vortex. If this is a fixed mount on a horizontal/flat flange face then a baffle or two would be in order. He also noted that all mfg’s now have a CFM analysis that should be able to jump right on your problem whereas he worked from notebooks and tables. He also stated that it has been his experience that the connection you have between the drive and shaft is not his first choice.
He asked was this a change in service from the original design?
RE: wobbling agit. shaft due to vortex in tank
Is Shaft an integral part of a pressure containment system or not . As per general engineering practices shafts design criteria is different than those of pressure containment system (Pressure vessels). To comploy with the ASME Code, what material shall be suitable for use as ASME SEC VIII applications?
Thanks
M. A. Bhutta
RE: wobbling agit. shaft due to vortex in tank
The shaft itself isn't considered part of to the vessel. You are to use the best available practice and compatible materials for it's construction. If possible the mixer shaft seal should be of a standard design like ANSI or API this is not a requirement it just saves a little design verification work.
The work comes in the form of the design of the vessel penetration where the shaft is located. This penetration has to meet the requirements of the jurisdictional vessel codes as a minimum and needs additional consideration given to the mechanical loads imposed by the mixer.
Most of the mixer suppliers will work with you on the mixer and seal if you supply the compatibility of materials to your process. Most will not verify the vessel penetration design this is up to the vessel designer.
RE: wobbling agit. shaft due to vortex in tank
There is somewhat of a consensus, more like a plurality, on this end that a description of the your shaft during operation is called "Whipping". The problem encountered in the discussion was whether the shaft had a circular orbit or was following a figure 8.
RE: wobbling agit. shaft due to vortex in tank
DMAB
RE: wobbling agit. shaft due to vortex in tank
The renewed yahoo mail facility grants 10mb of single file transfer and 100mb of mail space. Can you remail it?
Regards,