RIMS tube PID settings

Discuss tuning PID coefficients to maximize system efficiency.
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clearwaterbrewer
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RIMS tube PID settings

Post by clearwaterbrewer » Fri Oct 14, 2011 1:11 pm

I made a new sankey MLT so I had something sturdier than a 10 gallon cooler to mount my RIMS tube to.

The RIMS TEMP probe is about an inch or downstream from the element in the RIMS tube, and BCS PID configuration was default except for Integral, which was set to 0.2

The MASH TEMP probe is just a thermistor inserted into a stainless dip tube and dangling in the water for now, (looks like I need to mount steady from the graphs if I do want mash temp.)

On the first test, it ramped up nicely, but just kept oscillating around the setpoint..
RIMS test data log.png
RIMS test data log.png (29.45 KiB) Viewed 29092 times
I zoomed in and also changed the Derivative to 4:
RIMS test data log2.png
RIMS test data log2.png (48.7 KiB) Viewed 29092 times

I tried changing max and min integral to 10, which did not help.
I lowered proportional to 10 and then to 5:
RIMS test data log3.png
RIMS test data log3.png (33.97 KiB) Viewed 29092 times

so my final numbers for now are:
P= 5
I= 0.2
D= 4

clearwaterbrewer
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Re: RIMS tube PID settings

Post by clearwaterbrewer » Fri Oct 14, 2011 3:33 pm

I added some water from the hose ( I was running dish washing detergent through my chiller and cleaning keg at same time ;-)

here is the recovery graph:
The attachment RIMS test data log4.png is no longer available
The attachment RIMS test data log5.png is no longer available
Looks like I need to have a better mash probe location, and I think with a grain bed MASH TEMP will be a LOT more stable...
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RIMS test data log5.png
RIMS test data log5.png (61.55 KiB) Viewed 29082 times
RIMS test data log4.png
RIMS test data log4.png (70.47 KiB) Viewed 29082 times

gbrewer
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Re: RIMS tube PID settings

Post by gbrewer » Sat Oct 15, 2011 9:09 pm

You need to move your Rims Tube Temperutare probe away from the element. You will not achieve accurate controls with the RIMS Tube probe within 1" of the element.

Which temperature probe is controlling the relay for the element?

ohio-ed
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Re: RIMS tube PID settings

Post by ohio-ed » Tue Oct 18, 2011 5:55 am

What's wrong with the first configuration (graph) you showed?
Looks like your mash ramped steadily and hit your setpoint. The RIM's tube oscillated but never appeared to get too hot (IMO), in fact not more than about 5f above your setpoint. What improvement are you looking for?

Ed

clearwaterbrewer
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Re: RIMS tube PID settings

Post by clearwaterbrewer » Wed Oct 19, 2011 8:00 am

gbrewer - the position is close, but I think I have a high enough flow rate.. and there is enough thermal mas for short pulses.. (I forgot to lower the minimum pulse, doh! will play again in a day or so)

ohio-ed - It never never stopped cycling, and temp fluctuations too large.. I am not controlling based upon mash temp, only rims outlet temp...

pic of sensor placement:
IMG_0591.jpg
IMG_0591.jpg (73.78 KiB) Viewed 29044 times
close-up:
IMG_0592.jpg
IMG_0592.jpg (54.84 KiB) Viewed 29044 times
in context:
IMG_0593.jpg
IMG_0593.jpg (101.07 KiB) Viewed 29044 times

clearwaterbrewer
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Re: RIMS tube PID settings

Post by clearwaterbrewer » Sun Oct 23, 2011 4:22 pm

Here is the graph from my first automated batch, 5 gal of Dale's Pale Ale clone..

I was really happy at the temp control with the minimum pulse set to 1 sec on the RIMS tube heater..

Notes -

1 - the initial MLT temp spike is me having strike water too hot and throwing about 10 ice cubes into the mash to lower the 156 degree mash to 151
2 - the dip in the HLT at about the same time is from the HLT not recirculating...
3 - the ripple in the RIMS temp at mash-out is me determining the proper maximum pulse to keep the tube from boiling the wort and shaking all the hoses, which was somewhat entertaining..
4 - this is a 60 minute mash, 1.5 hours from start to filling BK with 168 degree wort.. 15 minutes before this time, 15 to start boil, 60 minute boil, and 30 to chill and fill fermenter yielded a 3.5 hour brew day (with the exception of putting things away, as I had everything but the BK and chiller cleaned by the time I filled fermenters...)
5 - the BCS allowed me to do other things during the mash and monitor the system from my phone... In other words, I got the yard mowed ;-)

20111022 mash.png
20111022 mash.png (45.2 KiB) Viewed 29020 times

RDH_Texas
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Re: RIMS tube PID settings

Post by RDH_Texas » Wed Dec 11, 2013 8:36 am

Hello, clearwater brewer,
What times did you use for output period and PID sample period?
In my RIMS system, when I try to use PID, the controller will turn the element on for a very short time regardless of set point. I'm thinking I've got some sort of issue with the time periods. They are set at the defaults which seem pretty short, but changing them has not done much for me so far.
I've got a 1500W element in a brewers' hardware tube, ~ 18" in length, with the temp sensor at the opposite end of the tube. I run the wort through the RIMS using a march 809, with a manual valve setting reducing the flow rate by about 50%, so maybe 1-2 GPM, but I have not measured it yet.
I hope I can get traces like what you posted eventually, I've had to resort to using the hystersis mode for the time being.

cheers,
Bob

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