Effectively Dry Grain in a Bin

How can you effectively dry grain inside a bin? That's the million dollar question and it can be done. Farmers have been drying grain inside bins for years with varying success. There are a number of factors that do affect drying grain inside a bin and the more you can pay attention to these factors, the more successful you will be.

Every farmer knows that to store grain inside a bin, the moisture and temperature must be within the safe grain storage range. The warmer and tougher the grain is, the shorter the

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storage time. If the grain is not conditioned properly a farmer will end up with lower quality grain and possibly a mess to clean up.

Traditionally farmers often wait until the grain fully dries in the field, but that's not always possible and typically it is not the most economical option. Waiting for grain to dry in the field brings added risk due to unforeseen weather and damage due to pests. The longer you wait to harvest your crop, the more chance there is that the crop will be damaged by wind or rain. Mature crop is also susceptible to damage from wildlife or other pests. Leaving wheat standing in a field longer than required can result in more losses due to pests such as sawflies. Harvesting the grain earlier and getting it in the bin reduces these risks, but it then comes back to the issue of having to condition the grain.

Benefits of Drying Grain

There are many benefits to drying grain instead of waiting for it to dry in the field as outlined in the paper "Heated-Air Grain Dryers". This paper was published in 1980 and the reasoning and logic still remains. Some of the benefits they provided were:

Longer Harvest Season

By having a grain drier, farmers can start to harvest earlier which allows for more efficient use of machinery and extra hours of harvesting time. It also allows farmers to start harvesting earlier in the morning and run later into the night. In some situations, a grain drier could replace the need for purchasing an extra combine.

Harvest Earlier

Crops such as wheat, oats and barley can be harvested as high as 20% moisture content. if you wait for the crops to dry to 14% it may only take a couple days in August, but by the middle of September it might take four days or more for the grain to reach 14%. That means extra days where unfavorable weather conditions can occur.

Reduce Field Losses

By leaving a crop in the field there can be unforseen losses due to weather, pests or wildlife. The longer a crop is left out, the more susceptible it is to these conditions. Leaving a crop out can also lead to lodged crops and possibly a loss in quality, which reduces the price per bushel. If a crop is overdried in the field it can also lead to shattering and more losses when harvesting. In some areas crops still aren't always straight cut, which means another field operation to windrow the crops. If the crop can be dried in the bin, it may make it possible to straight cut more crops and reduce the need for swathing.

Eliminate Spoilage in Storage

It's common for crops to be stored in a bin until it can be sold. For this to happen it must be dry and cool, but field conditions don't always allow for this. Having the ability to dry grain provides the flexibility to take grain off when it is ready to be harvested and still safely store it.

Benefits of Doing In Bin Drying

When drying grain there are a few options to successfully get it done. Large grain dryers are tempting because they can can dry a large amount of grain relatively quickly. The drawback to these grain dryers is that they take a lot of infrastructure. The grain has to be moved to the dryer and then away from the dryer when it is dry. There are different ways that this can be done, ranging from automated systems to having to use trucks and augers. No matter how the grain is moved to and from the dryer, it takes machinery and there is a cost to it. The dryer itself also requires a significant investment to purchase and a grain dryer uses a large amount of fuel to heat the grain. So although dryers have their place on some farms and can be useful, there is a high cost to owning and operating one.

In bin storage is an efficient method of drying grain. It takes longer to to dry grain inside a bin, but for the majority of the drying process the system can be unattended. When drying inside a bin it doesn't require moving the grain, it can all be done in one process inside the bin. The energy requirements for drying inside a bin are also much lower. An Airblast natural gas fan can dry grain for under 1 cent per bushel and an Airblast propane fan can dry grain for just over 2 cents per bushel.

Things to Consider For In Bin Drying

There are a few things that need to be considered when drying grain inside a bin. Controlling these factors will make grain drying more efficient and successful.

1. Airflow

   Airflow is likely the most important variable to consider when drying grain inside a bin. Simply put, the more airflow there is, the faster and more even the grain will dry. The way the grain dries is by transferring moisture from the grain to the air. The more air that flows through the grain, the more moisture can be picked up. Traditionally bin fans were designed for aerating, which requires 0.1 cfm per bushel of grain so a 10,000 bushel requires 1,000 cfm of airflow. When trying to dry grain the airflow is ten times as high so 1 cfm per bushel is recommended (PAMI's Comprehensive Natural-Air-Grain-Drying (NAD) Factsheet). Finding ways to get more air through the bin is crucial for proper drying. Airflow is affected by things like the type of ducting inside the bin, the size of the fan, the depth of the grain and the type of the grain.

   
   

   Airblast fans are similar to 20 hp electric fans. This results in higher airflows than what most farmers are running. A typical fan size for a 10,000 bushel bin is 7.5 hp or 10 hp. Neither of these fans provide enough airflow for effective drying. An Airblast fan moves more air, improving the drying rate.

   
   

2. Bin Ducting

   The ducting inside a bin affects how much airflow there is an how it is distributed inside the bin. In general, the more surface area of perforation a ducting system offers, the more airflow there is. The position of the ducts in the bin also plays an important role. An inverted V is an effective method to get air into a bin, but it results in lower airflows and much higher rates of drying around the V. The result is slower drying and uneven drying.

   
   

   The DRYit Radial Flow developed by Wavcor starts at the top of the hopper and extends a minimum of 12 feet up from there. This puts the air into the core of the bin where hotspots are more likely to develop. With the wall channels, air travels horizontally from the central duct out to the wall channels. This reduces the distance the air has to travel through the grain, which results in higher airflows. The outcome of this system is faster, more even drying inside the bin.

   
   

3. Heat

   Heat always speeds up drying, but there is a cost to adding heat and if not done properly it can cause other problems. The benefits to adding heat typically outweigh the negatives of a heater. Adding just a little heat to the air stream can improve drying dramatically. Increasing the air temperature by 10°C cuts the humidity in half. This can mean taking a bad drying day to a good one. To truly understand the effects of temperature and humidity, an understanding of the equilibrium moisture content (EMC) is required. Most heaters burn propane or natural gas. Depending on the type of heater it may come with challenges to keeping it functioning properly. Heat also adds additional costs because there are the costs to purchase the heater, as well as the operating costs. Typically it is advisable to add around 10°C to air when trying to dry. If more heat is added it can cause condensation on the bin roof and walls.

   
   

   Airblast fans offer free heat. A natural gas or propane engine is used to spin the fan. When the engine is running a by-product is heat. Heat from the engine is captured and added to the airstream. This typically results in an increase of air temperature of 10°C. The heat that is added is clean and dry because all the moisture and exhaust gases are deposited outside the fan body.

   
   

4. Bin Venting

   When drying grain inside a bin, as the air passes through the grain it picks up moisture from the grain. Often times this grain is also warm. When the warm, moist air reaches the bin walls or roof it, the moisture can condense and collect. In this situation the moisture may rain back down on top of the grain causing the top of the grain to get wet and can cause localized areas where there is spoilage. PAMI recommends one square foot of vent space for every 10,000 cfm of airflow.

   
   

   The DRYit Radial Flow directs the airflow from the center of the bin, outwards to insulated wall channels. The air enters the bin and travels up the channels and exits through roof vents. The wall channels are insulated to prevent moisture from condensing on the bin walls and the air is vented directly outside so that moisture cannot condense on the bin roof.

   
   

5. Grain Mixing

   Grain mixing is not required for drying inside a grain bin, but it does make the process much more efficient and even. The most common method of mixing grain is to take some out of the bin and move it to another bin or to put it back into the top of the bin. This does offer some mixing, but the amount of blending is limited and it is labor intensive. Mechanical stirring augers are also available, but these are costly and require maintenance as well as electricity to run them.

   
   

   Wavcor is working on a new mixing system that utilizes airflow from the fan to mix the grain. This offers a low cost, efficient method to slowly turn the bin while the grain is drying. This new system does not require manual input to move the grain and it does not require any electric stirring augers. It is truly the easiest and most efficient way to mix grain while stirring. This is currently in final tests with plans to relase the product in late 2025.

Drying grain inside a bin can be done and it can be done very efficiently. Utilizing Wavcor's lineup of products for in bin drying the guesswork can be taken out of drying, making your operation more efficient and convenient. Contact Wavcor today to explore the options that will work for you.