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EconoDri Grain Drying System

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EconoDri/VAL6 Grain Drying Process


The conventional grain-drying process is accomplished by burning propane as a way of raising the air temp.  As warmer air moves through the grain, it encourages the grain to sweat its surplus moisture and the airflow eventually picks up the moisture and carries it out of the storage bin.  The interesting flaw in this is that open combustion typically CREATES humidity, so you're trying to remove humidity from wet grain by using wet air.  It's like being all sweated up from a workout, and going into a sauna to dry out, an analogy that seems to convey why conventional drying techniques are not the most economical techniques to accomplish grain drying.
Some people are skeptical of the statement, “open propane combustion elevates humidity”.  I usually ask them if they've ever been in an insulated shop in the winter, and operated a typical space heater, and noticed humidity/condensation forming on the walls, fogging windows, etc.   They usually have, and I tell them, that’s an example of the humidity created by open combustion.  Another example is when people ask why exhaust/chimney temps are so high when you use waste oil furnaces or wood stoves.  Bearing in mind that you have ash deposits with both, if you do not have high chimney temps (which create aggressive, higher speed draft/exhaust), the combustion humidity will bond with the ash, and create a tar-like substance inside the chimney and heat exchanger, which eventually becomes the reason for chimney fires.  
A mental image I try to share is that of having a wet sponge in one hand, and a wet sponge in the other hand, and putting them together.  Where would the water go?  Nowhere.  Each sponge is wet.  There's nowhere for the moisture to go.  It would take a long time to dry the sponges out, this way.  Then, I ask if they had a wet sponge in one hand, and a dry sponge in the other, and put them together, where would the moisture go?   Obviously, with the 2 sponges touching together, the moisture would travel/migrate from the wet sponge to the dry sponge.  Then I tell them, substitute dry air for the dry sponge, and you should be able to visualize what's happening. 
You will get some temp rise with the EconoDri/VAL6 process, which is a bonus, but the real drying takes place because of the dry air.  The wrap-around design of the EconoDri is to collect the radiant energy into a mass that will experience temp rise and elevate dehumidifying.  The airflow created by the blower does the rest.  If you put the VAL6 close to a blower, (with no EconoDri) the high velocity moving air will typically create a cooling effect on the VAL6 radiation disk. The glow on the radiation disk is critical to the fuel efficiency, kind of a catalytic converter effect, if you will.  If the disk is cooled down by the force of the intake fan, you will lose the radiant effect.  Any un-burnt fuel will be vacuumed out of the VAL6 burn chamber and then into the bin.  This fuel/air mix will have a higher monoxide coupled with lower heat/higher humidity.   

Another aspect of the wrap-around design is the funnel shape.  You know that you can't really force a liquid through a funnel?  The EconoDri funnel will allow air to progress only at a predicted rate.  That thought is part of the reasoning in the internal collector, and the cabinet, too.  You want to get the most air flow that the system is capable of, but you don't want to seal the EconoDri to a high CFM blower that possibly pulls air so much faster, that you start to see the cooling effect I referred to above.  The simple solution is to adjust the distance between VAL6 heater and the EconoDri.  If a single EconoDri/VAL6 system is used, you can improve the air flow drying quality by adjusting the distance of the VAL6 heater from the wide end of the EconoDri.  If the blower is capable of more CFM, it simply needs to be able to access "make-up" air externally, so the blower isn't starved of its rated CFM flow.  By pulling the VAL6 heaters away from the EconoDri you allow the radiation disk to reach its full potential and allow more ambient air into the system.  This is where the EconoDri wedge shape is compatible with pairing up units to provide extra capacity for the blower to access, i.e. if surplus CFM air is needed; a second EconoDri/VAL6 side by side will provide it.
The wetter the grain is, the heavier it is.  This grain weight in the bin translates into more airflow resistance, (called static pressure) and even though the blower may be rated for "X" CFM, it will not be able to force “X” CFM through increasingly wetter grain.  So conversely, a higher percentage of the air that IS getting pushed through the grain is the dryer EconoDri/VAL6 air.  The EconoDri does its best work, the wetter the grain is.
The conventional drying equipment people that I have talked to, have told me that the propane drying options on bins can range from $3500-$6500, depending on sizing variables.  I point out to prospects that conventional propane drying equipment is designed only for that application, and will likely never be separated from the bin.  In other words, one inefficient application, multiplied by however many bins are involved.  It is also unlikely that the drying equipment will ever be used on any other bin than that which it's attached to, even as expensive as they are, because the conventional equipment is difficult to move around.  Stored-grain airflow MUST be maintained at all times  The portability of the EconoDri/VAL6 is so easy that you can use them sequentially from bin to bin, in singles/multiples as you wish, and when you're done with the grain, you've still got the best heater on the market for your shop, etc.  What initially seemed like an expensive space heater/EconoDri combo, paid for itself in fuel savings alone.  Your VAL-6/ EconoDri combo's have virtually paid for themselves the very first time you use them.
There is one last variable, and that is the almost non-existent monoxide.  When we've run our simulations, we have never gotten an operational monoxide reading higher than 1-2 ppm.  Interestingly, by contrast, one day a neighbor who smokes happened to walk over to where we were operating the CO tester, and it bounced up to 50+ parts per million. Conventional propane grain drying isn't allowed for human consumption foods.  Popcorn, white corn, dry edible beans, soybeans, etc, are higher value crops because they ARE for human consumption.  The higher monoxide that goes with propane, will bond a taste/odor that will reject it under testing, which is pretty stringent.  I have high hopes that we may have another direction here, but it will take some judicious testing and experimenting.
Let me also say this. I believe all of the above to be accurate and true. Our feedback has been positive in general, with a few cautious neutrals at worst. When the wet fall turned into operations trying to make use of the EconoDri's and VAL-6s, everyone was frantically trying to get their harvest done, and no one was willing to screw around with time-consuming side-by-side comparisons and experiments. They had a wet crop to get out, and woe to the guy who would suggest that they waste time, somehow.  General comment was that significantly less money was spent drying grain, but it was experience-based, and seldom documented.  The conventional drying options available can't give hard facts/predictions of drying speed, because so many variables affect drying capacity like the infinite variables of the grain moisture, ambient relative humidity, (which affects the air's starting humidity point), wet grain static pressure, (the resistance to airflow), and probably other minor variables that I can't think of, right now. 
At the end of the day, the EconoDri/VAL6 combo offers grain dryers a low cost alternative that is realized with the first bin they dry.  The initial hardware costs are matched by the fuel savings and a drying method that eliminates moisture from the start.  After the grain is dry you have a top-of-the-line diesel fired heater that’s safe for indoor/outdoor use all winter long.  No smoke, no fumes, no toxins, and quiet using 2/3rds less fuel than the conventional forced air heater. 




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