Natural air drying with supplemental heat

[poorboy]

I have some harvesting left to do yet, mostly canola and wheat. I am thinking about buying supplemental heat to use with my natural air drying system. I see you can buy systems with little bits of heat that add 100,000 btu's all the way up to monster systems that add 300-500,000 btu's. The big heat salesmen claim you can dry 4% points off in 4 days.

Any one have any experience with either route, good or bad? Would the higher heat systems work in early september to dry 4% points off wheat in 3-4 days or would the 100 degree farenheight air 24 hours day in early september be too hot and the grain would sprout before it would dry?

[fvoth]

You should have dry grain using this method but at what a price. What promoters of this concept do not realise is that way grain dries. Grain in a bin dries from bottom through to the top with a drying front. Grain does not dry from 18% down to 14% but dries through the drying front to whatever the moisture equilibrium is.
A rule of thumb, which you can verify from charts from the University of Nebraska, is for every 20 degree F you increase the temperature of the outside air you cut the relative humidity in half.
At 70% RH that means you would have 35% RH - the grain would be dried to about 10.5%. Your overdying cost would be about 4.7% of the value of the grain plus the cost of fuel and electricity.
Over drying is very expensive. Over dried grain is water you can not sell. You will have dry grain but the lost income of drying is a hidden cost. There is a lot more that can be said on the subject. I think you can also go to ND State University site and download brochure on the shrink factors. A grain dryer can be controlled to avoid these losses. Generally if you can afford one of these small heaters you can afford anything it's not cheap drying but you should have dry grain if done right.

[FarmRanger]

fvoth is right. I have a grainmax 3000 bin that I had about 7/8 full. I had a 60000 BTU burner on 18.1 durum for about 5 days. When I unloaded it in 7 loads, the top 2 were 16.9 and 17.0. The next 5 were 15.3, 13.9, 13.5, 12.9 and the bottom of the bin was 12.5. Perhaps if I had only filled it 50 to 60% full, and dried for less time.
Used between 3 and 4% of a 1000 gallon propane tank, plus the electricity to run a 3 hp fan for most of a week. I moved that grain to another bin with a temperature cable in it, so I will continue to monitor it. Basically, thats a lot of time for the amount of grain I dried.

[poorboy]

I am led to believe that by adding supplemental heat, especially lots of supplemental heat is that the grain needs to be taken out of the bin and mixed well when the average moisture is dry. For example in wheat, the bottom is probably 10% moisture and the top is 18% moisture, yet the bin will average 14% moisture.
Or perhaps you just dry one bin to 10-12% moisture and leave 2 bins at 18% moisture and then have the elevator blend the wheat for you and average dry. You would have to keep the tough wheat cool or it would spoil.
My problem is that according to environment canada the average high is 12degrees C and average low is -1 degree C and most info on natural air drying says you need air that is 10 degrees C or higher to dry grain. So, for this year I am not sure what is best.

[FarmRanger]

I was wondering about mounting a small auger vertically in the bin, and use it to mix the grain while you dry it. Has anyone tryed this?

[wd9]

Good info: res2.agr.gc.ca/winnipeg/storage/pubs/heatdry.pdf

Aeration is great if the weather is nice and warm outside and the grain needs about a percent to dry otherwise pick up a used or invest in a new continuous flow dryer. Probably less investment than a supplemental heating system (capital and operating cost) and you can consistently dry that 3000 bushel bin of grain to exactly 14.5% even if it is rainy and cold. The setup need not be fancy.
Just my experience, again aeration has a place, it is just not a dryer, it's more of a moisture equalizer, or allows product to be protected until it can be dried.

[fvoth]

wd9 has the right concept but for smaller amounts of grain an all electric auto batch dryer such as a Farm Fans, SuperB or GSI is much more convenient, easier to use and take a lot less supervision than a continous flow dryer. Check into this concept before investing in a continous flow.

[fvoth]

FarmRanger - there are bin stirators that look after the problem. Suppliers are DMC, Sukup and Neco among others.

[wd9]

Good point fvoth, the difference is in how much grain to dry. Once you have the dryer set up, more grain will be dried to get the crop off in better condition and this should be considered. If there is only a small amount of grain (< 5000 bushels), a small recurculating batch would be more cost effective.

[poorboy]

As an update, I purchased an air-o-matic heater and put it on my aeration fan and it dryed my 14% canola down to and average of 8% in about 4 days. It cost approximately 8 cents a bushel for natural gas and power. The bottom canola was severly overdry, so the system only works if you empty the bin and mix the tougher canola on the top with the over dry canola on the bottom. It got to about 5 degrees C in the day and -8 degrees C at night, and it rained and snowed one night.

Overall, I am extremely happy. Keep in mind that it will have to be mixed and dumped into another aeration bin to equalize the moistures.