Coal hopper level sensing

Hi friends,

I have a customer that is looking for some advice on upgrading the level system in their coal hopper. It is at a coal bagging plant and this hopper feeds the bagging line. They run everything from rice to stove coal through here. When they coal is dry, it isn’t very dusty, so when the coal is wet, it is a damp environment. They are currently using bindicators but aren’t very pleased with their accuracy. Esp. When running larger coal, their are large enough voids betwee the pieces of coal that the sensor thinks the level has gone down. Because of the dust and dirt, I shy away from any sort of prox or photo eye. Because of how the coal will pile, I don’t think a radar or sonar would be a good idea either. I suggested a load cell, but they would like not to have to use them if possible because it would take a lot of modifications to their existing setup.

Any advice on what sensor you would recommend form this set up? They currently have two sensors......one for on and one for off. They would like one sensor and we would use a small plc to do control the start/stop. Also then our high and low levels would be much more configurable.

I have a project on the books to install 4 of these. It works well on sand and alumina, don't know if it would work for your application or not but might be worth looking at.

https://www.emerson.com/en-us/catalog/rosemount-5708-solids-scanner

Any sensor used will need to be class 2 div 1,2 - dust
since you added the damp part, it will need to be cleaned regularly and kept away from coal since the coal can damage the sensors.

if the system is in the mine itself, it may need to be class 1 div 1,2. - gas fumes.

you will need intrinsic barriers and install using the nec 70 500 -5?? sections for hazardous environments.
don't forget to use seal offs!

my 2 cents,
james

Our black coal hoppers are all on load cells. Is this an option for you?

To add to James Mcquade comments, our hoppers also have a CO2 inerting system installed.

Lynx777 said:

I have a project on the books to install 4 of these. It works well on sand and alumina, don't know if it would work for your application or not but might be worth looking at.

https://www.emerson.com/en-us/catalog/rosemount-5708-solids-scanner

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Those are pretty cool. They look like they may do the job, although I didn't read much of the documentation yet.

James Mcquade said:

Any sensor used will need to be class 2 div 1,2 - dust
since you added the damp part, it will need to be cleaned regularly and kept away from coal since the coal can damage the sensors.

if the system is in the mine itself, it may need to be class 1 div 1,2. - gas fumes.

you will need intrinsic barriers and install using the nec 70 500 -5?? sections for hazardous environments.
don't forget to use seal offs!

my 2 cents,
james

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This is not in the mine itself but is in the processing plant at a different location.

Guided wave radar may be an option: https://www.flowcontrolnetwork.com/how-guided-wave-radar-level-measurement-works/

Bit_Bucket_07 said:

Guided wave radar may be an option: https://www.flowcontrolnetwork.com/how-guided-wave-radar-level-measurement-works/

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+1 For radar. This is what we used on the feeders at a coal fired power plant years ago, and it worked flawlessly.

Bubba.

willxfmr said:

+1 For radar. This is what we used on the feeders at a coal fired power plant years ago, and it worked flawlessly.

Bubba.

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Thank you. This looks like a viable option. But I struggle to grasp exactly how this works. By all appearances, it transmits a signal and waits for a return pulse. But what is the value of the probe? My biggest concern with using a sensor of this style would be that with the coal piled up in the hopper, that the signal would be bounced off the side of the pile at an angle and never return to the sensor. Would this probe (guided wave) solve that issue?

lesmar96 said:

Thank you. This looks like a viable option. But I struggle to grasp exactly how this works. By all appearances, it transmits a signal and waits for a return pulse. But what is the value of the probe? My biggest concern with using a sensor of this style would be that with the coal piled up in the hopper, that the signal would be bounced off the side of the pile at an angle and never return to the sensor. Would this probe (guided wave) solve that issue?

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Yes. The ones that I have used in coal silos employed a cable as a wave guide.

https://www.ifm.com/cz/en/shared/technologies/3d-sensor-o3d/3d-sensor-o3d-startseite

I suggest you look at this O3D sensor from IFM.

I use a few of them. In a wash down environment completely exposed they have lived up better than expected. Talking to my PLC and giving me any data I want. Three pre-programmed applications in the sensor are "Level Detection", this is what I'm using this for, it works very well giving you back the MM value or Inches value of material in your hopper.

It also has a box height detection application for sorting and one for counting already pre-built.

Its easy!

+1 for the guided wave radar. Not just regular radar, but guided by a cable.
The various ultrasound types I have tried are too sensitive to dust when filling the silo.
Same for regular radar.

Strain gauges can be retrofitted to the pillars that hold the silos. But the silos must be independently supported.

In a previous life, I worked around some coal mines and plants. We generally used radar on silos and loadout hoppers, but we worked on a couple of installations that used Texas Nuclear level gauges mounted to the sides of the hopper. Worked like a champ, until someone that needed to weld something on the hopper decided to clamp his ground to the metal housing of the gauge.

I have been doing a good bit of researching and am leaning towards the guided wave radar because it seems to make the most sense for the application. But this is the first time I am using these, so I want to make sure I have everything figured out.

Is there a specific brand that you have used, like, and would recommend?

lesmar96 said:

I have been doing a good bit of researching and am leaning towards the guided wave radar because it seems to make the most sense for the application. But this is the first time I am using these, so I want to make sure I have everything figured out.

Is there a specific brand that you have used, like, and would recommend?

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I've used Endress+Hauser: https://www.us.endress.com/en/field...evel-measurement/Guided-Radar-Levelflex-FMP57

No complaints.

Bit_Bucket_07 said:

I've used Endress+Hauser: https://www.us.endress.com/en/field...evel-measurement/Guided-Radar-Levelflex-FMP57

No complaints.

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I've also used E+H and they're great, as well as Vega guided wave transmitters with excellent results. They're coming out with their PLICSCOM modules that are Bluetooth configurable as well (optional).

https://www.vega.com/en/home_us/Products