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Repeatability Issues Due to Chaff Combustion During Roasting??
GABSTER
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Posted on 12/27/2018 12:24 AM
Hello,

I am new to the forum but I have been roasting on a B2K+ Hottop for close to two years now and I am finding it very hard to achieve repeatable results mainly due random heat spikes generated as chaff particles occasionally land on the heating element and burn.

The extra heat energy released is enough to interfere with the ROR and make it even more challenging to control the roast let alone achieve repeatable results.

MY QUESTION IS:- Has anyone else experienced the same issue?? And, has anyone found a way around it ??

Please let me know..

Kind regards Grin
 
renatoa
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Posted on 12/29/2018 5:03 AM
I doubt chaff has so much energy to move temperature even one degree...

I seen RoR influenced more by improper acquisition than anything else.
I mean the lack of sync between Artisan READ requests and effective acquisition time.
There could be delays ranging from 100 to 900 ms that creates a beating phenomenon, that many perceive as noise, but is not.
A good graphical representation can be see in this picture:
https://pages.mtu...tgraph.gif

In our case the two frequencies that "beats" are the Artisan and TC4 sampling intervals. Even we set both equal, say at 500 ms, beating still occurs because there is the unknown and random processing time of both parts.
A real sync must be done between the two parts, to make this beat disappear. For example TC4 acquisition be driven by the Artisan READ commands, and not by its own internal sample clock.

In our world, this beating can be seen in the attached picture, this is not a real roasting process, but a computer simulation, in order to develop a PID alternative controller.
Those RoR oscillations are not real, plotting the real data in excel draws fine curves, is the beating phenomenon I wrote above.
...
renatoa attached the following image:
beating_sim.png
 
GABSTER
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Posted on 12/30/2018 2:54 AM
Thank you Renatoa for your informative response.

I had not considered beating as a possible cause and it may explain some of what I see especially when the peaks in the ET and BT ROR traces occur at exactly the same spot on the time axis.

However, when the two peaks occur at slightly different times and are displaced in time relative to each other then my guess is that the thermocouples are reacting to some heat source that may be closer to one sensor than the other and hence the time displacement.

Below is an Artisan graph of a recent Roast I did that demonstrated what I experience from time to time and I have been attributing some of this to chaff burn (rightly or wrongly)Grin

Let me know what you think.

Kind regards,

Gaby
 
GABSTER
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Posted on 12/31/2018 9:19 PM
Having trouble attaching my profile picture Shock
 
renatoa
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Posted on 01/01/2019 2:14 AM
Edit your post and check bottom area, Choose File button.
 
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