1. GRAIN DRYING AND GRAIN DRYING METHODS MUHAMMAD HAMMAS IRFAN STUDENT AT AGRICULTURAL ENGINEERING BZU MULTAN (36-AG15)

2. GRAIN DRYING Grain drying refers to the removal of some of the moisture from grain by mechanically moving air through the grain after it has been harvested. Grain in the field dries naturally as the crop matures, giving up moisture to the air un­til the grain moisture is in equilibrium with the moisture in the air (equilibrium moisture content). Conditions become less favorable for grain to dry to moisture contents considered safe for storage as the harvest is delayed into late fall.

3. DRYING ADVANTAGES Increases quality of harvested grain by reducing crop exposure to weather. Reduces harvesting losses, including head shat­tering and cracked kernels. Reduces dependency on weather conditions for harvest. Allows use of straight combining for small grains. Reduces size and/or number of combines and other harvest- related equipment and labor re­quired due to extending harvest time. Allows more time for post-harvest field work. Permits long time storage of grain without deterioration. Permits continuous supply of product thro’ out the year. Makes products available during off season.

4. DRYING DISADVANTAGES Original investment for drying equipment and an­nual cost of ownership. Operating costs for fuel, electricity and labor. Extra grain handling required may result in further investment for equipment.

5. INFLUENCE OF DRYING CONDITIONS Airflow rate Air temperature Air relative humidity Increase in temperature increases the moisture carrying capacity (RH reduced). *Rule of thumb, Temperature increment by 20F doubles the moisture-holding capacity of air and cuts the relative humidity in half. Difference in moisture content (Grain and Air). Higher static pressures decrease fan output. Higher airflow rates give higher drying rates.

6. INFLUENCE OF DRYING CONDITIONS Airflow is determined by fan design and speed, fan motor size and the resistance of the grain to airflow.

7. TYPES OF DRYERS Dryers can be categorized in different ways. There are natural air, low temperature, and high temperature dryers; there are batch, automatic batch and continuous flow dryers; and there are in-bin and column or self-contained dryers. Dryers can also be classified according to the direction of airflow through the grain; cross-flow, counter-flow, and concurrent- flow. Natural Air/Low Temperature Drying Layer Drying High Temperature Bin Drying Batch-in-bin Drying Recirculating Bin Dryer Continuous Flow Bin Dryer

8. TYPES OF DRYERS Column Dryers Column Batch Dryers Continuous Flow Drying Combination Drying

9. NATURAL/LOW TEMP. DRYING Bushels (bu)

10. LAYER DRYING

11. RECIRCULATING AND CONTINUOUS FLOW DRYERS

12. COLUMN BATCH DRYER

13. CONTINUOUS FLOW DRYER

14. MOISTURE SHRINK The removal of moisture from grain during drying causes a reduction in grain quantity referred to as moisture shrink. The moisture shrink can be calculated using the following equation. Moisture Shrink (%) = (Initial M.C. =Final M.C.) / (100 – Final M.C.) x 100

15. REFERENCE(S) Grain Drying, Dr. Kenneth J. Hellevang, PE. Extension Agricultural Engineer, North Dakota State University (NDSU), Fargo, North Dakota. October 2013