Corn Drying

The longer you wait to harvest corn, the dryer the kernels will be. But you need to get all of your corn harvested before the plants get blown over and the weather is too bad to get into the field. That means that you need to start combining before the kernels are dry enough to store safely (e.g. won't mold or mildew), which is below 13%. (Wikipedia)  So farmers install grain dryers.

I remember that my Mom's cousin was real glad when the power company installed 3-phase power lines down their road to serve the new Prairie Heights Community Schools that were being built to the East of them. That means the motor for his grain dryer would be cheaper. In his case, it was a big fan attached to one of his grain bins. And a big propane tank setting next to the fan because the fan included burners to heat the air. A quick check of a manufacture's product line shows that 13-hp is the smallest fan they make. Since the limit for single-phase power is normally considered to be 5-hoursepower, I now understand the importance of the 3-phase electrification.

Farm Fans C2100

Several manufactures, e.g. Brock, GSI, Mathews, Sukup, Delux, and Farm Fans, make standalone dryers for a farm. I'm surprised how many manufactures there are for a technology that is now decades old. Evidently batch dryers are now obsolete because they all looked like continuous-flow dryers. As with in-bin drying, they all throw electricity (air flow) and propane (heat) at the problem. Below are some of the specs I found for the model pictured on the right. First of all, note that the 3-phase models use significantly fewer amps. And single-phase models are not even available for the bigger versions. Secondly, the biggest model needs 154*230=35420 watts. That is equivalent to 354 100-watt light bulbs or almost 35 1000-watt air dryers. That will make your electric meter spin pretty fast.

Fan(s)	2	2	2	2
Top	28" 13HP	36" 15HP	39" 20HP	39" 25HP
	1750 RPM	1750 RPM	1750 RPM	1750 RPM
Bottom	28" 10HP	28" 10HP	28" 13HP	28" 13HP
	1750 RPM	1750 RPM	1750 RPM	1750 RPM
Heater(s) BTU/HR(MM)
Top	3	4.6	6	7.5
Bottom	2.3	2.3	3	3
Augers
Top Auger (HP/BPH)	5HP/1800	5HP/2800	7.5HP/2800	10HP/2800
Bottom Auger (HP/BPH)	3HP/955	3HP/1225	5HP/1360	7.5HP/1770
Metering Roll Drive	1/3HP DC SCR	1/3HP DC SCR	1/3HP DC SCR	1/3HP DC SCR
Electrical Load (MRA) - Excludes auxiliary load and unload equipment amps
Single Phase 230 Volt	146	187	-	-
Three Phase 230 Volt	92	96	135	154
Three Phase 460 Volt	46	48	68	77

And the biggest model I found sucks 408 amps at 230 volts. Given that a 12-gauge copper wire is good for only 20 amps, I'm trying to picture how big the wires would be to feed these dryers.

So as a farmer grows his operation, he not only has to build more storage bins and get a bigger combine, he has to get a bigger dryer.

Commercial grain elevators use continuous tower dryers. Many of the postings that have Grain Elevator in the title will have pictures of the grain dryers. Most of these dryers are connected to a natural gas feed rather than propane tanks.

Update: Dryers are also used for other grains such as wheat.

The dryer can be clearly seen in the Utica, IL, elevator.

20141013 0153

The Ashkum Grain Elevator has two grain dryers. The big white building obscures the gas feed to the building, but you can see how big the pipe is that supplies gas to the facility.

20141013 0149, cropped