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Roasted Coffee Bean Storage

08/07/2021 2:12 AM

Hi CR4 Community, just looking at a project involving the storage of Roasted Coffee Beans. The project involves 12 storage hoppers to store various roast / Bean combinations. The customer requested the use of Endress and Hauser Ultrasonic Analogue Level Sensors, but the design of the Hoppers using this sensor may prove unreliable. The Hoppers are 3.5m High x 0.8m x 1.2m, when taking in the filling apron, it doesn't leave much room for an ultrasonic sensor, and also the DC value for Coffee Beans is quite low. If the Hopper was larger it wouldn't be so much of a problem. But it is what it is!

I was thinking, that we may have to change the sensors to Lazer Distance Sensors, with these sensors should not be affected by dust, and give an accurate indication of the hopper level.

Your opinions are appreciated

Best Regards

Joe

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#1

Re: Roasted Coffee Bean Storage

08/07/2021 4:04 AM

Wouldn't it be better to go by weight...?

..."One of the most advanced radar instruments uses 80 GHz frequency modulated continuous wave (FMCW) radar (see Figure 2) for continuous level monitoring. This instrument has a short-wave length of only 4 millimeters (mm), along with a narrow beam path of just 3 degrees. The combination of a short-wave length that performs well in powders and small particle solids, and a narrow beam that does not see or reflect off objects, makes FMCW radar ideal for certain solids applications. FMCW radar provides high accuracy of ±3 mm in solids at a relatively low cost compared with prices from five years ago."...

https://www.processingmagazine.com/process-control-automation/instrumentation/article/15587313/level-measurement-in-solids-applications

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#8
In reply to #1

Re: Roasted Coffee Bean Storage

08/08/2021 8:02 PM

I don’t have much experience in coffee beans, but weight would be the best… I know that moisture of the green coffee beans affect the quality, I don’t know what it is for the roasted codpiece bean.

But you may have to incorporate a tare for the weight… one example to take into consideration is the moisture of the roasted coffee bean as well as the size and quality of the bean.

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#2

Re: Roasted Coffee Bean Storage

08/07/2021 9:30 AM

I agree with SE. Weight measurement would seem to be much simpler and more reliable.

I would think ultrasonic and laser level measurement would be better suited to liquid level measurement where there is a level surface to provide a reflection.

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#3

Re: Roasted Coffee Bean Storage

08/08/2021 4:57 AM

The slump angle in a pile of newly roasted coffee beans will depend on the amount of residual fats/oils in the beans. A narrow beam instrument cannot compensate for this variable. I agree that load cells is the better option. Three temperature compensated, 6 wire, load cells per hopper, creating a tripod base, will give a more accurate reading than the E & H units, at a comparable price. They will also be much easier to calibrate both initially and to keep calibrated over their working life.

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#4
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Re: Roasted Coffee Bean Storage

08/08/2021 2:22 PM

I agree, but the problem is that 4 hoppers are fabricated together to reduce the overall footprint and the amount of steel being used for the fabrication.

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#6
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Re: Roasted Coffee Bean Storage

08/08/2021 6:00 PM

Do each of the four segments have their own coned section above the outlet valve? If so suggest cutting the cone off and inserting a flexible between the cone and the hopper sides plus a second flexible below an outlet valve which is supported from the cone. Then each cone can be suspended from the hopper sides by three S type tension load cells while the rest of the hoppers and support steel work remain on the existing legs. This will achieve accuracy without too much additional expense.

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#9
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Re: Roasted Coffee Bean Storage

08/08/2021 8:02 PM

Nice info, when I was a teenager, to make extra buck, I was the ‘tare master’ of a cherry relieving station for incoming cherry’s from the orchards.

I like your details.

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#5

Re: Roasted Coffee Bean Storage

08/08/2021 3:51 PM

Quick question, is dust actually going to be present in the hoppers to (potentially) cause a measurement issue?

Can you reduce the max fill height so the customer doesn't fill past a certain height if you think it will result in a measurement issue, or perhaps accept or add an offset that just shows the hopper full until it drops below a certain level before the measurement becomes accurate?

Is it really important for the customer to see that the level drops from say 98 to 96 to 94 to 92%, etc full instead of say 98, 98, 98, 94 to 92%, etc? Aren't they just interested in when they have to refill from this specific measurement rather than exactly how large the portions are (which is controlled and monitored elsewhere in the process)?

Jack - A tea drinker.

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#7

Re: Roasted Coffee Bean Storage

08/08/2021 6:45 PM

You may have a problem with getting laser reflection from dark beans, plus a rough surface will tend to diffuse the reflection in many different directions.

Perhaps guided wave radar? Knowing the dielectric constant at time of inquiry will help confirm suitability quickly.

Echos from ultrasonic transmitters can be difficult to predict, especially if the product peaks on sides or center. The window of time between pulse & listen is also a problem with small tanks.

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#10

Re: Roasted Coffee Bean Storage

08/08/2021 11:05 PM

I have used ultrasonics to measure distance in all manner of bins, some on liquids, some on powders , lime and flocculent, some on large coal >12mm, some on small coal <12mm. With bins from 3m deep to outdoor stockpiles of 25m height.

The sensors do have a minimum range but a standpipe built to house the sensor and of sufficient diameter so as not to impact the sound cone angle will allow the bins to fill right to the top and cause no problems. One needs to make sure that the filling position does not impact the sonar beam.

If feeding into a PLC then by the use of an F of X function the bin physical parameters can be programmed in and the depth converted to volume. Even odd shaped bins can be programmed into the software.

The ones installed have been running since 1983 and are still in operation.

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#12
In reply to #10

Re: Roasted Coffee Bean Storage

08/09/2021 5:58 AM

I have used load beams for storage beam weighing. That was by far the easiest apporoach to this storage beans for cacao and coffee and mjuch more for dairy manufacturing. Time is very long back, starting about in 1986!

This system does not have any impactg from temperature of the material. Bin walls had been alu, stainless steel and for Sugar I used Trevira fabric.

josef

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#13
In reply to #10

Re: Roasted Coffee Bean Storage

08/09/2021 11:18 AM

It looks like there is limited headroom to install a top hat to be able to measure near the top. Also, the aspect ratio of the bin will require a very narrow beam transducer, if that will work at all. Flat side tanks make very effective reflective surfaces, making echo processing difficult. If a laser source has enough strength to create a reflection from a dark and diffusive surface, that would be a good selection. Otherwise guided wave radar is the only technology I can see that might work within the parameters given. E&H offers that equipment

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#15
In reply to #13

Re: Roasted Coffee Bean Storage

08/09/2021 2:45 PM

The Radar would work, I think from memory the DC for roasted beans 4.5, so the radar would work.

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#14
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Re: Roasted Coffee Bean Storage

08/09/2021 2:42 PM

I agree the standpipe would solve many problems

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#11

Re: Roasted Coffee Bean Storage

08/09/2021 4:19 AM
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#16

Re: Roasted Coffee Bean Storage

08/17/2021 8:09 PM

I was going to agree with the weight measurement method but you mentioned that the silos are joined together, which pretty much eliminates weight as an option.

There's a technology called 3D level measurement. It's a type of radar that determines not just the height but the shape of the material inside the silo. The issue with ordinary radar or ultrasonic is that the material may form a standing cone (after filling) and then an inverted cone (while emptying) that can affect the reflections of the signal causing errors. Modern sensors have compensating software but these make assumptions instead of actual measurements.
A low-tech solution would be to use several point-level sensors (such as vibrating fork sensors). Install ten of these along the sides of a silo at different heights and you get a low resolution level measurement system. If you're requirements is just for level measurement, this will work fine. If you need to know the actual mass of product in the silos, you'll need to go with the other technologies.

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#17
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Re: Roasted Coffee Bean Storage

08/17/2021 8:43 PM

I have got the customer to modify the storage bins as they don't require as much storage as previously anticipated, the bins are now 2000mm in height to the bottom of the cone, by designing in a Top Hat to compensate for the Dead Zone of the Ultra Sonic Sensors, I think we can do it with the FMU-41 E&H Sensor.

The ultrasonic sensors that are in use on the site for green beans seem to operate at about 15-20% accuracy and they are happy with this.

Fitting Vibratory Fork Sensors, would just add to the cost of which I am trying to reduce, these would require additional wiring, fabrication, additional inputs, and programming. I don't want to go down this path as it is just more things to go wrong.

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#18
In reply to #17

Re: Roasted Coffee Bean Storage

08/18/2021 1:01 AM

I've done the multiple level sensors before and never had problems with them. But if your clients are happy with 15-20%, then go for it.

regards,

Vulcan

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#19
In reply to #18

Re: Roasted Coffee Bean Storage

08/18/2021 1:19 AM

Thanks Mate

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