Dolomitic lime detection

Maybe somebody has a simple solution for me on this one. I have 2 small silo's one with Dolomitic lime the other with powdered lime. They are deliverd by rotary feeders, into a wye, into a common chute.
When a order of lime is requested the rotary feeder revolutions are counted,based upon known lime weight and area of the rotary bin, until the order is achived. The problem lies, if the lime silo's bridge over above the rotary, no material falls into the rotary feeder. I need to know that material is comming out of the rotary feeder. I need a sensor that will see the lime comming out of the rotary feeder.Any Idea's?
Thanks
Bengolfin

Are you really using this method for measuring a specified amount for an order ?
How do you determine the exact amount the customer has to pay for ?

There are two ways for measuring "stuff" when money is in the loop:
- Volumetric. I dont think this can be used for your application.
- By weight. This looks like the solution to your problem.

If the only problem currently is the bridging in the silo's, you may be able to add Airbrator's to the silo's to eliminate the bridging. We have used them in the past to solve this problem and had good success. Checkout binmaster.com

look at this

The SITRANS AS 100 is an acoustic sensor for flow detection. It detects changes in high frequency sound waves from equipment and materials in motion. After detection, it reacts instantly to changes in solids flow to warn of blockages, product absence or equipment failure such as burst filter bags. This allows an operator to take early preventative action and avoid costly damage. Common applications include pellets, powders and most bulk solids in pipes, chutes, vibratory feeders, pneumatic conveyors or aerated gravity flow systems.

Used in conjunction with a vibrator as Bob mentions,would be my answer, no need to run a vibrator when the flow is good.

http://www.milltronics.com/search_results.asp

I have used the previous generation of this device and it worked quite well, looks like they have discontinued it though as I couldn't find reference to it at the Milltronics website. It bolted to the outside of the chute so was not affected by the chemical nature of the product. (Lime being corrosive)

Does the amperage used by the auger screw motor change when the silo is bridged? I have used this in the past to tell me if an auger is jammed full and churning the material.

There are some inexpensive switches that trip if amps are too low or too high. Cost about $35 out of Grainger.

not amps, not on screwfeeders

One would think you could measure amps (or horsepower) of
the motor driving a screw feeder and make determinations
based on that measurement.

One would be wrong.

Most of the energy in a screw feeder is simply used to keep
the screw moving, loaded or not. And, even when loaded,
if the material fluidizes, the 'mechanical' load decreases.

I'd look at one of the 'dry flow' sensors that use acoustics,
or a mechanical 'paddle switch' of some sort. I don't remember
the name of the company, but if you google 'plugged chute detection',
that should do it.

And the bridging, as big a problem as it is, could be
solved with air activation or side mechanical activation...but,,
even with all that, there could still be a bridge (or 'rat hole')

Re: not amps, not on screwfeeders

jdbrandt said:

I don't remember the name of the company, but if you google 'plugged chute detection', that should do it.

Click to expand...

Might you be thinking of Bindicator products, Jeff?...

beerchug

-Eric

Thank all of you for the input, We are looking into the Milltronic's flow detection devices, some look very promising.At this time, We are adding air stirring in the Silo's above the rotary feeders to stop the bridging, and installing some capistive proxes in the path of the lime flow as it drops from the feeder. But long term it looks like redesigning the silo's, spliting them and adding scales so we can be more accurate with the amount of material delivered.
Thanks
Bengolfin

The air's got to go somewhere

If these silo devices get air injected in the bottom, don't
forget that this injected air will kick up dust, and the
air will need to go somewhere. Likely it will take the
dust with it, so you'd better consider some sort of
dust collection with this solution, unless it is already
installed.

And I looked for plugged chute detectors on google... the
name I'm looking for didn't show up. I think its Monitor,
or something similar.