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Grain Aeration, “Just the Basics, Ma’am”

Grain Aeration, “Just the Basics, Ma’am”. Tri-State GEAPS Workshop Amarillo, TX Jan. 18, 2007. Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. . Why Do We Aerate?. Condition grain by cooling to safe level for storage

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Grain Aeration, “Just the Basics, Ma’am”

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  1. Grain Aeration,“Just the Basics, Ma’am” Tri-State GEAPS Workshop Amarillo, TX Jan. 18, 2007 Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

  2. Why Do We Aerate? Condition grain by cooling to safe level for storage Uniform cooling prevents moisture migration Very powerful IPM tool With more air, used for grain drying Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  3. Aeration as IPM Tool Control insects by cooling to < 60° F 15°F drop (ex: 90° to 75 °) reduces activity 50 – 75% Very powerful IPM tool Aeration = Crop Insurance!! Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  4. Suggested Plan for Southern States At binning, cool to mid 70’s using nighttime air Mid September, aerate second time to low 60’s Can prevent the need to fumigate Eliminates insect population buildup and damage Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  5. Suggested Plan for South General suggested rates: Steel bins and flat storage: 0.1 cfm/bu (1/10th cfm/bu) Concrete upright bins: 0.05 cfm/bu (1/20th cfm/bu) For southern states: 0.2 cfm/bu at least, 0.25 to 0.3 is best if affordable At 0.3 cfm/bu: takes 30-35 hours of nighttime cooling to drop 15° in summer Expect wheat shrinkage of about 0.8% Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  6. General Design Factors…What to consider Grain Type (coarse vs. small) Location/harvest date Storage structure Available energy Cooling speed vs. energy cost (cool as fast as you can afford) Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  7. Specifics…What to consider Airflow rate (fast is better …insurance) Grain airflow resistance Wheat static pressure = 2x corn or soybeans Propeller vs. centrifugal fan type Airflow direction (suction or pressure) Distribution (ducts or perforated floor) Control (manual or automatic) Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  8. Components Fans Ducts…transition and supply Floor distribution system Roof vents, exhaust fans Controls for fan regulation Pressure switch on fans for negative pressure systems Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  9. Calculating Cycle Time AT = aeration time, hours/cycle AR = airflow rate, cfm/bu TW = test weight, lb/bu Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  10. Cycle Time, Flow Rate, and Test Weight Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  11. Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  12. Positive or Negative Airflow Negative Airflow: Pros… Reduced condensation under steel roofs Cooling zone movement estimated by fan exhaust air temperatures Can hold covers on outdoor grain piles Cons… Needs larger transition/duct cross-section areas (especially in flat storage) Roof damage if vents freeze (use neg. pressure switch) Top grain heat moves through all grain Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  13. Positive or Negative Airflow Positive Airflow: Pros… Distribution in flat storage is more uniform Add warm grain w/o heating cool grain Aeration zone finished when surface grain cools Less plugging of perf. floors or ducts Cons… Condensation under steel roofs Heat of compression raises air temp. 3-10° F Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  14. Fans Centrifugal and axial Use FANS program from Univ. of Minnesota or Purdue Factors: power, efficiency, multiple fans in series or parallel Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  15. Fans Axial Van-axial Tube-axial (small - 2Hp or less) Low cost, noisy 3 – 5 inches static pressure Centrifugal 1460 to 3500 rpm Higher cost Quieter More airflow per HP above 5” static pressure Fan Performance…consult manufacturerinfo. Sheets, AMCA certification is best info. Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  16. Fans Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  17. Fans – selection in a nutshell Optimum performance Efficiency based on cfm/hp Noise, cost, reliability, mounting dimensions, space Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  18. Air Distribution Systems Consist of… Transitions, manifolds, supply ducts Perforated ducts, pads or false floors Roof vents or exhaust fan systems Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  19. Transitions Air Tunnel Transition smaller than air duct tunnel is BEST! Foundation Transition Fan Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  20. Transition/Supply Duct Air Velocities Maximum design air velocity… positive pressure: 2500 fpm negative pressure: 2000 fpm Preferred design air velocity… positive pressure: 1500-2000 fpm negative pressure: 1000-1500 fpm Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  21. Perforated Distribution Duct Velocities… Upright storages: 2000 fpm Flat storages: 1500 fpm Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  22. C A C B Airflow Path Ratio A + B <= 1.5 C C: duct to grain peak A + B … longest path Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  23. Round Bin Floor Layouts Pad. Square “Y”. Double “T” Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  24. More Floor Layouts – Large Bins Double Pad Quad “F” Double “H” Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  25. Vertical Aerator …Big Bins with Dia:Sidewall > 2.5:1 Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  26. Perforated Floors Cereal Grains: 3/32” diameter perf. Smaller Seeds: 3/64 to 1/16” Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  27. Coring to Improve Aeration Can reduce cooling time and costs up to 30% Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  28. Flat Storage Duct Layout • Less airflow under valleys • More airflow under peaks • Requires non-uniform distribution to get uniform delivery!!! Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  29. Half-round Duct for Hopper Bin What about Hopper Bins? Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  30. Roof Venting Pressure System needs exhaust vents 1 ft2 cross-section area per 1000-1500 cfm Suction System needs inlet vents 1 ft2 cross-section area per 800-1000 cfm Keep static pressure in bin head space to 1/8” or less Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  31. Vent Types Gooseneck Vents Mushroom Vents Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  32. Roof Exhausters Types Power Vents 200 – 250% of aeration rate Run when aeration is on plus 15-20 minutes Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  33. Controllable Roof Vents Normally closed Designed to open under pressure or vacuum Interlocked electrically with fans Reduces insect infiltration Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  34. Fan Controllers Temperature limit thermostats Humidity control NEMA 4R housing Hour meter, selector switch Time delay relays (TDR) for multiple fans Off-the-shelf components Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  35. RH and Temp Controllers Partial list of vendors OPI The Boone Group AgriDry Rimik Pty GSI Caldwell/Chief-Agri Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  36. Cost Estimates Aeration System: 6.0 – 12.0 ¢/bu Controller: 0.3 – 1.0 ¢/bu Temperature Cables: 0.3 – 1.0 ¢/bu Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  37. Monitoring Systems • Least expensive • Most expensive Manual Readout and log book Data Logger with manual plug in to thermocouples Computer interfaced automatic monitoring Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  38. OPIGIMAC Temperature and Insect Monitoring, Aeration Fan Control System Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  39. More New Technology Closed Loop Aeration working with CLF system in sealed storage Cross-Flow Aeration As much as 30% less power than vertical airflow Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  40. More New Technology USDA Electronic Insect Monitoring System now commercialized by OPI as “the Insector” Purdue Univ. working on a mold sniffing system to detect development of mold by CO2 detection Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

  41. Info-Siteshttp://www.biosystems.okstate.edu/home/jcarol/http://www.biosystems.okstate.edu/sare/Info-Siteshttp://www.biosystems.okstate.edu/home/jcarol/http://www.biosystems.okstate.edu/sare/ Acknowledgements: USDA and Cooperative State Research Education and Extension Service Dr. Ron Noyes, Grain Storage Engineering, LLC, Stillwater, OK (OSU Professor Emeritus) Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept. Stillwater, OK

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