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Propane Control with a Dwyer DH3 Diff Pressure Controller
johndolz
Top  #1 Print Post
Posted on 12/23/2024 1:36 PM
Hi folks,

I got myself in and over my head on this one. Luckily I have a very knowledgable friend (not knowledgable about coffeesmile) who is doing the work - I'm just trying to gather some info for him.

I have a Mill City/North 500 gram roaster (from the very 1st shipment). It was suggested that I upgrade the needle valve and original pressure gauge with something digital for much better control/repeatability.

I have a Dwyer DH3-009 differential pressure controller to control the propane flow, but no solenoid yet (upgrade from the manual needle valve). It seems like it'll drive a relay to open/close a solenoid. To him, it looks like this is similar to turbocharger boost control. In hindsight, I would take a simpler approachsmile. Purchased this a few years back, the price now is INSANE!

Is it as simple as setting a high and low set points, and let the solenoid buzz open/closed? Proportional Solenoid? Any concern about burning out the solenoid with too many cycles? Or should the pressure lines have an orifice to slow down response?

Suggestions on setpoints? And on what solenoid to get? Gas line is 1/4" NPT...

We'll need to buy a relay, solenoid, and a 24V AC or DC power supply (can be either). I figure you guys have done this before, so he doesn't need to re-engineer the wheel.

Thanks for the suggestions!
 
Yasu
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Posted on 12/23/2024 3:39 PM
I use a CKD flow controller.
They have one specifically for LPG and are very reliable for industrial use.
It can indicate flow rate with 4-20mA, so it can be used with analog dials and temperature regulators.
I connect it to a temperature regulator and use PID control.
I don't know if it is available in your country. 、、、、、

https://www.ckd.c...&sid=0
 
johndolz
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Posted on 12/23/2024 3:47 PM
Thanks, looks like a custom order here in the US but available. My "techspert take a look, appreciate the help!
 
Yasu
Top  #4 Print Post
Posted on 12/23/2024 3:58 PM
I'm glad to see it's available in North America.
It is a bit expensive, but since I put it on, it is like a world of difference.
It is like having a craftsman controlling an invisible human gas barf.
I look forward to seeing it boldly introduced.
 
johndolz
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Posted on 12/23/2024 4:37 PM
Not quite the right timing in life but I am in for so much already that there is no stopping nowRoflmao
 
zeece
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Posted on 12/24/2024 1:16 AM
Yasu, does this device work well when you need a very low flow rate, like in the late stages of a roast? Is it consistent and repeatable? What is the maximum flow rate of the CKD FCM device you are using? And how did you decide on that maximum value? Thanks very much for any insight you can provide on which model to choose.
 
Yasu
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Posted on 12/24/2024 1:59 AM
I need the burner requirements for equipment selection.
In my case, I use a 10KW burner with reduced pressure down to 20KPA, so
I used a low differential pressure type burner.

Under these conditions, the CKD part number is
FCM-L0010.

The selection was FCM-L0010 with a flow rate of 6 l/min at 10 KW.
For a smaller burner, FCM-L0005, one lower, might be okay.

For a general burner, maybe a low differential pressure type (which I did) would be the way to go.

The minimum flow rate can be set and I set it to 0.3 l/min to prevent misfire. (I use a manual valve to bypass a small amount of gas, as this valve is safe and will fully close with an error if the range is exceeded).

It is probably faster to lose the burner than to reduce it to the minimum flow setting.

I think it is important to reduce the pressure of LPG gas to 20 KPA.
The pressure reducing valve should be a pressure reducing valve attached to a gas cutting cylinder, such as those found in ironworking shops.

Low to high flow rate accuracy and repeatability, but
The displayed flow rate and air temperature after combustion are the same every time and I trust it very much.

Please ask any other questions you may have.
Yasu attached the following images:
2024-12-24_164905.png 2024-12-24_164803.png
Edited by Yasu on 12/24/2024 2:51 AM
 
Yasu
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Posted on 12/24/2024 2:13 AM
The attached image shows IT = air temperature after combustion
LPG Rate is the value of gas volume l/min.
It is a part of the data logged by artisan.
You can see that the gas volume and combustion temperature are finely controlled.
Yasu attached the following image:
2024-12-24_170955.png
 
zeece
Top  #9 Print Post
Posted on 12/24/2024 11:40 AM
Very helpful. Thank you. Time for me to run some calculations.
 
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