Corn Harvesting And Drying
URBANA, ILL.
Mike Roegge, University of Illinois Extension,
Adams/Brown Unit, reports that
this years' corn harvest is going to place
quite a demand on grain drying systems, both
on farm and at the elevator. It's been years since
we’ve seen the kind of harvest we're likely to be
facing this year. I’ll be the first to admit that I
know very little when it comes to improving/increasing
the efficiencies of grain drying systems.
But I’ll try and summarize some of what I’ve
read.
There are a number of factors that affect grain
drying, including: grain moisture, air flow, temperature
(outside, grain and heated air), humidity,
type of drying system, etc. But some factors
are going to be the same, regardless of the drying
system you have. One of those would be air
movement. Generally speaking, the more air you
can move, the better conditions you would have
for drying. There are certain minimum air flows
required based upon grain moistures and temperatures.
The lower the heat, the higher you’d
like the air flow to be. The higher the heat, the
quicker and more efficiently you’ll lower the
grain moisture levels.
Following are some grain drying tips taken
from Dr. Ken Hellevang, NDSU. The entire paper
is located at:
http://www.extension.org/pages/Postharvest_Tips_for_Later-maturing_Corn.
High temperature grain drying- Using the
maximum drying temperature that will not damage
the corn increases the dryer capacity and
can reduce energy consumption. The amount of
energy required to remove a pound of moisture
is about 20 percent less at a temperature of 200
degrees versus 150 degrees. However, remember
too high of temperatures can lead to increased
cracking and lower test weights. Also with
higher moisture corn, lengthened drying times
with high temps can lead to corn browning and
discounts.
In Storage Cooling– using in storage cooling
rather than in dryer cooling will boost your capacity.
It requires airflow rates of about .20
cfm/bu or 12 cfm/bu-hr of fill rate. Cooling
should start immediately when corn is placed in
the bin. About 1 percentage point is removed
during corn cooling.
Dryeration– will increase dryer capacity by 50
percent or more, and reduce energy by 25 percent
and remove about 2-2.5 point of moisture
(.25 points for each 10 degrees corn is cooled).
Place the hot corn from the dryer into a bin, let
sit for 4-6 hours without airflow, then turn on
the fan to cool it. You must then move to a different
bin. There will be a tremendous amount of
condensation, so you must move the corn to a
different bin.
Estimating costs for high temperature dryinguse
the following formula: cost/bu. point= 0.022
x propane cost/gallon. For example, the drying
cost is 2.9 cents/ bu. point if the cost of LP is
$1.30 (0.022 x $1.30) It will cost about $34 for
LP to remove 10 points of moisture from 120 bu
of corn using $1.30 propane. The estimated
quantity of propane needed to dry is 0.022 gallon
per bushel per point of moisture removed.
For example, 26 gallons of propane is needed to
dry 120 bushels of corn from 25 percent to 15
percent (0.022 x 120 bushel x 10 points).
Test weight will also increase as corn moisture
decreases. Normally, test weight increases about
0.25 pound for each point of moisture removed
during high temperature grain drying. However,
mechanical damage during harvest and gentleness
during the drying process can affect test
weight. In ND last year, due to mechanical damage
involving 25-30% moisture corn and high
drying temperatures, there was sometimes no
test weight increase. There will be little to no test
weight increase on immature (frost damaged)
corn.
Remember also to account for shrink when
drying grain. To dry corn to 15.5 percent moisture,
the shrink factor is 1.1834. The shrink
drying corn 5 points would be 5 x 1.1834= 5.92
percent. Δ