Reading mositure content of a biomass?

[skyfox]

Has anyone done this type of an application before or can point me in the right direction?

Biomass is corn husk. it can be partially dried or still in green state at the start of a dry cycle. It is being dried inside a vessel using heated compressed air applied using stainless steel spray bars mounted inside the vessel. Heated air exits from a 6 foot long 3/4" ID pipe mounted on top of the vessel.

I was thinking about mounting a Dew point sensor inside this exhaust pipe to get a reading. But not sure how to go about converting that Dew Point reading to a value that would reflect the remaining moisture content of the Bio mass. Weight of the biomass is known before the cycle is started. However, weight of partially dried and still green corn husks are not known independently. Only the combined final weight of 50 to 100 lbs. I would like to use a Dew point sensor if this can be accomplished using one, as we have them readily available in shop stock.

I would be very thankful if someone familiar with this type of process can chime in and give me some pointers on correct way to go about this.

Thanks.

 

[James Mcquade]

I would go to your local grain company where you sell your grain.
they have moisture sensors they use for every load of grain that comes in from farmers. you can get the brand name and model of what they use.

james

 

[skyfox]

I would go to your local grain company where you sell your grain.
they have moisture sensors they use for every load of grain that comes in from farmers. you can get the brand name and model of what they use.

james

Hi James,


I am looking for a instrument with Analog voltage or mA output to connect it to a PLC. So the grain store variety would not help me in this case.


Thx.

 

[jraef]

I've done something very similar, measuring the moisture content of air in a drying oven for ceramic roof tiles. I used a Relative Humidity (RH) probe in the return air duct, which output a 4-20mA signal that I put into a PLC as the Sp of a PID loop controlling the temperature based on the rate of change (we didn't want them drying too fast or they cracked). I used RH probes that I got from Omega but lots of people have them. The trick is in knowing the RH range you need to work with and then you may have to determine the values that you want via empirical data (basically trial and error unless you find someone with knowledge of the desired RH for corn husks).


A friend of mine designed a system for measuring the moisture content of hops a long time ago, which is maybe more akin to your application. He used a probe that actually dropped down into the bins in the kiln to measure the RH inside of the pile of hops, so he had a little robotic overhead crane that traveled along the drying barn and would drop the probe into the bins at different points to ensure it was drying evenly. I know that the secret to his success was the probe itself, something he adapted from the Portland Cement industry. That was over 20 years ago, I just looked for him and it appears there are a LOT of people in that game now. That might be a way for you to tackle this because it seems to me the way they do it is going to be very similar to what you are doing.

 

[sbaum]

As jraef mentioned the concrete industry uses moisture sensors that can be adapted to other products.
Check out Hydronix https://www.hydronix.com/index.php or Mesa Systems Co http://mesasystemsco.com/


Or if you have deeper pockets you could consider NIR analyzers.

 

[skyfox]

Thanks Jraef & sbaum,


Thank you all for your suggestions and insight. I will look in to sensors from Hydronix & Mesa sysytem's units. Quick look around and not being able to get a general idea of what they might cost, tells me that these devices are more than likely going to be cost prohibitive to this particular customer.I do have a DP sensor that is switchable between DP & RH. Might give that a go and see if it will work out. Unit we have looks identical to the one on OMEGA's website and specs are identical as well.


Thanks again for helping out.


Cheers.


Cheers.