fluidizing a railcar 1

[grandmanitou]

Hi,

We presently unload terephthalic acid (white crystaline powder) from a rail car by gravity. The problem we have is that when the compartment is almost empty, we need to fluidize the railcar with nitogen. We use a pneumatic rotary vibrator to enhance the flow, but it doesnt seem enough to fully empty the car. Anybody knows a better way to avoid the high consuption of nitrogen?

 

[Barry1961]

There is a process that is used to "instantize" dry powders such as flour and protein that makes them very easy to mix with water. It also greatly reduces the angle of repose. This is not a new process but it is becoming more popular in powders that need to be mixed with a liquid.

My experience with this is with protein powder which roughly has the same properties has fine white flower. If you buy the “instantized” version it has roughly the same properties as granulated table sugar in mixing and angle of repose.

I do not know what the process is to do this but it did not increase the cost of my protein.

Barry1961

 

[bklauba]

It could well be that the pneumatic vibrator was not sized properly. Can you supply details, such as the amount of material (weight and volume), and the force output and frequency of vibration? It would be best to get an actual reading of the vibrator's frequency, since the vibrator's operating condition, load, and the pressure and CFM available to drive it, highly influence a pneumatic vibrator's frequency.

BK

 

[MikeHalloran]

See if you can sweep the vibrator frequency. You're probably running it too fast.




Mike Halloran
Pembroke Pines, FL, USA

 

[bklauba]

A linear vibrator (pneumatic piston), having a 3" piston, or a 3.5" long stroke, would do a better job of keeping this material moving this material than a rotary vibrator, according to the best material flow guru I know.

BK

 

[ornerynorsk]

a set of 2 linear piston vibrators with each its own control so they can cycled in and out of phase with one another, and thereby varying the amplitude, should do the trick.

 

[grandmanitou]

I've talked with one supplier, and he recommended a linear vibrator, which is better (rather than a rotary vibrator) for materials less than 70 pounds per cubic foot.
They suggested a 3.5 inches piston.

For the one I have, I dont have any equipment to verify at what frequency it's turning.

Ornerynorsk, how do you install two piston on a railcar, because their is only space for one?

 

[bklauba]

If you are working with rotary vibrators (or other gear) regularly, check out the deceptively simple device called a Vibra-Tach. These devices are about the size of a pencil (a bit longer and thicker), and consist of an aluminum body, from which can be extended a stiff steel wire to various lengths. They have two models, with different ranges.

The body has a scale, calibrated in RPM X 100. Adjust the wire so as to cause it to vibrate at its max amplitude, and the scale reads out the vibrator's speed to within about 2%, which is often good enuff to address many issues. Handy device, and easy to use.

BK