Measuring material in a hopper

cornbread · Jan 26, 2012

A bit off topic, but I thought this learned group may be able to help. Here is my problem, I have a 3 ft diameter cylinder that is used as a feed hopper, the material in the hopper is akin to a charcoal bricket. Current operation is to manually measure how much material has been consumed (via a tape measure). It’s measured from the top of the cylinder to the top of the brickets (usually we measure between 8 to 10 feet). Looking for away to automatically measure the distance. Tried several optical devices but the area is very dusty and they have proven unreliable. I’m currently looking at using some sort of slip wire to measure distance. Any suggestion would be greatly appreciated.

mellis · Jan 26, 2012

You want it reliable? Measure the weight. There are load cells you can retrofit to the hopper. Of course, there are probably limitations based on your existing installation but you should be able to get reasonable accuracy.

Mrslipmat · Jan 26, 2012

Have you thought about ultrasonics or laser ? I used a IFM distance measurment laser to do the same sort of thing you want to do, it worked no problem even with the dust issue, Scaled the analouge output to the distance of the hopper size when empty and full. This measured concrete and aggrigate in several bins and displayed the contents on a HMI screen...

Regards

JV

Bob O · Jan 26, 2012

http://www.binmaster.com/SmartBob/sbindex.html

TWS · Jan 26, 2012

Guided Radar level transmitters are another option.
like these: http://www2.emersonprocess.com/en-u...uided-wave-radar/3300-series/Pages/index.aspx.

Just one of many vendors.

JesperMP · Jan 26, 2012

Does it have to be accurate ? If so, I think loadcells is the only real solution.

If you only need to know approximately how full the silo is, then ultrasonics may be the solution. The tricky bit is to not trigger on the material falling into the silo, or support structures inside the silo. We are starting to use ultrasonic sensors more and more. We dont need to know exactly how full a silo is, only if silo 1 is more full than silo 2 etc. Our environment is also very dusty.

widelto · Jan 26, 2012

I have used Hardy Technology load cells with compactlogix Plcs from AB with excellent results.

Mrslipmat · Jan 26, 2012

Ultrasonics is the way forward... I use them on our water tanks for levels and they are pretty accurate... I found with load cells on the hoppers had a huge varience dependant upon the dampness of the product going in. imagine a bag of sand being weighed, then soak it in water and reweigh it... unless you monitored water content and took this into consideration the values would always be different and not consistent...

Regards

JV

tommy23t · Jan 26, 2012

I second Bob O with the Binmaster. We have several silos holding plastic pellets and used to pound on the sides to find our levels, real accurate. Although larger (12' dia x 40' high) the application is the same. We use the software from them and can measure from the office on demand, or you can setup a schedule.

We tried several ultrasonic products, but none were accurate due to the shape of the pellets.
Hope this helps,

tommy23t

JesperMP · Jan 26, 2012

Mrslipmat said:
Ultrasonics is the way forward... I use them on our water tanks for levels and they are pretty accurate...

Probably very accurate for liquids. Bulk solids are difficult to measure by looking at just the top. For example bulks builds a top when filling, and a depression when emptying. So if the ultrosonic sensor points to the center it will meassure too much and too little respectively.

Mrslipmat said:
I found with load cells on the hoppers had a huge varience dependant upon the dampness of the product going in. imagine a bag of sand being weighed, then soak it in water and reweigh it... unless you monitored water content and took this into consideration the values would always be different and not consistent...

What were you measuring ? Volume or weight ? If you measure weight and the density changes, an ultrasonic measurement will be off.

edit: Reading cornbreads description, I am guessing this has to do with burning charcoal, and he needs to know how much charcoal is being consumed, either for accounting or for regulating the process. So by that I guess it has to be accurate by weight, and there wont be any pollutants such as water in the bin. I say hang the bin in a single load cell.

kandymann · Jan 26, 2012

Ohmart VEGA Level Indicators work great

Mrslipmat · Jan 27, 2012

Hi Jesper, we were measuring the volume of sand, cement and aggregates in several bins and hoppers, the bin contents would change dependant upon the dampness of the product.... If the bins were loaded with wet sand and they dried out over the weekend the weight value would change in relation to the water content... this also effected the mix of the product when water was added so we ended up fitting moisture measurment on the mixers so we could calculate water content before mixing and adding more water for a optimum mix ratio... By the way the product was flag stones, kerb stones and block paving...

Regards

John V

cornbread · Jan 27, 2012

Appreciate the replies. Looks like the Binmaster is the most promising from my application.

danw · Jan 27, 2012

Siemens LR560 radar can shoot through fly ash and cement dust. It's incredible.

It has a very narrow, 4° beam angle:

At ten feet, the beam width is only 0.7 feet:

I would consider connecting an air line to the integral purge port and timing a 5 second purge every so often.

http://www.automation.siemens.com/w1/automation-technology-sitrans-lr560-19704.htm

Measuring material in a hopper

cornbread

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