Corn Storage and Drying – Spring 2009. Kenneth Hellevang, Ph.D., P.E. Professor & Extension Engineer Agricultural & Biosystems Engineering NDSU Extension Service. Corn Flowability. 28% moisture freezes together 24% - 25% some binding <24% to assure flow Foreign material affects flow.
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Corn Storage and Drying – Spring 2009
Kenneth Hellevang, Ph.D., P.E.
Professor & Extension Engineer
Agricultural & Biosystems Engineering
NDSU Extension Service
Bridging transfers load to the bin wall
CAUGHT IN THE GRAIN!
At least a N-95 rating
Average Maximum Temp.
February 1 - 15°
March 1 - 27°
April 1 - 45°
May 1 - 65°
Solar Radiation (Btu/ft2-day)
Feb. 21 17251800
Jun. 21 8002425
Periodically Cool Keep under 30°F
15 / cfm/bu = hrs
42’ diameter, 36 ft depth, Corn
3 hp. Axial Fan, 0.15 cfm/bu
Cooling time = 100 hrs.
Cover Fans When Not Operating
Cracked, broken, immature corn spoils easier
Corn Equilibrium Moisture Content
March 25°F & 76% RH, April 42°F & 71% RH
Minimum Recommended Airflow Rate For Natural Air Drying Corn
Wilcke and Morey, University of Minnesota Bu-6577-E, 1995
Limit Corn Depth
42 ft diameter bin, corn 36 ft deep, 1.0 cfm/bu
Fan = 180 hp, static pressure = 17-inches wg.
Corn: 21 ft. diameter, 20 ft. deep, 10 hp fan
Energy requirements of a conventional high temperature cross-flow dryer as a function of drying air temperature and airflow rate. (University of Nebraska, about 1970)
High Temperature Drying~210°F
Assumes 2,500 Btu/lb water
Propane cost / bu- point moisture = 0.022 x price/gal
$ 0.033/bu-pt = 0.022 x $1.50/gal
@ $1.50/gal propane, estimated propane cost to dry corn from 25% to 15% is $0.033/bu-pt x 10 pts = $0.33/bu.
Propane gallons = 0.02 x bu. x point moisture
Propane = 0.02 x 1,000 bu x 10 pts = 200 gallons
Moisture Shrink (%) = Mo – Mf__ x 100
100 – Mf
Example: Corn dried from 25% to 15% moisture
Shrink%= 25% – 15%__ x 100 = 11.76%
100% – 15%
(% weight loss/percentage point moisture loss)
Example: The moisture shrink drying corn from 25.5% to 15.5% is
10pts x 1.1834 = 11.8%
* Kernel Damage
* Drying Temperature
Normally ¼ to 1/3 lb/pt.
Dump hot, temper without airflow 4-6 hrs, cool, move to storage
Increases dryer capacity 50%-75%,
Reduces energy by about 25%
Immediately cool, Airflow rate 12 cfm/bu-hr of fill rate
Reduce condensation by partial cooling in the dryer
For More Information
Google: NDSU Corn Drying