Grain Dryers: Advanced Equipment for Moisture & Quality Control

The purpose of grain storage has remained the same for thousands of years: to maintain the quality of the crop until it can be used or processed into food.

The first choice is to harvest at optimal conditions, but that’s not always possible. There are a limited number of days when crops are at their peak in terms of ripeness. In addition, rain and snow can cause havoc with harvesting, greatly affecting the quality of the crop because of added moisture.

Sometimes farmers need to harvest wet crops that have moisture levels too high to be safely stored. Moist grains (farmers would call these grains “tough”) are prone to spoiling, overheating, becoming infested with insects or moulding, all of which reduce its grade or quality.

Not only does high moisture have the potential to reduce its suitability for human food, but a lower grade reduces how much a farmer is paid.

It’s all about quality. A farmer receives payment based on the grade of grain delivered to the grain dealer. Under the Canada Grain Act, the Canadian Grain Commission is the government body responsible for maintaining Canada’s grain grading system.¹ They also set the standards for what is considered safe moisture limits for storage.

Using grain dryers to prevent spoilage

Grain drying is the process where stored grain is dried from a high moisture content down to a much lower moisture level. It is an integral part of grain storage.

DYK? The ideal moisture content is 12-15% for most crops harvested in Canada.

There are three phases involved in grain drying:

Water inside the seed or kernel is pulled toward the outer wall.
Heat causes this moisture to be evaporated by the air.
High humidity air is released to maintain a dry environment.

Grain dryers use a flow of continuous hot air to remove the moisture released from the grain. It is a specific process that balances multiple factors to optimize grain dryer performance and reduce costs. This includes:

Time. Grain drying at low temperatures for long periods ensures grain quality, but it also takes longer. This reduces capacity (as only small volumes can be dried at a time).
Heat. Capacity increases as temperature increases, but grain damage can occur at high temperatures.
Airflow. High airflow rates increase drying capacity but decrease fuel efficiency and can be costly.

Plenty of options for every operation

Farmers select grain drying equipment that allows them to maintain low moisture and temperature levels to store their harvest for up to several months while minimizing costs.

Here are the different methods of drying grain.

Aeration

Aeration is when a small amount of air is moved through the bin using aeration fans attached to the outer wall of the grain bin. This helps keep the bin cool and will slightly reduce moisture. And even though it’s cost effective, it’s also the least efficient strategy to reduce moisture.

Natural air drying

This process uses a much higher airflow and supplemental heat. It’s especially useful when grains are not excessively wet. Fans can be controlled by a thermostat that senses the temperature and humidity inside the bin and adjusts the fan accordingly. The key to making this work is the airflow rate (the air volume that the fan pushes into the bin) as it requires sufficient air flow to circulate through the entire bin.

If farmers are lucky and conditions outside are dry, they may not need additional heat and can use only forced air to move high moisture air out of the bin. But without supplemental heat, this requires a higher rate of airflow to accomplish the job which may take weeks instead of hours or days.

Dedicated grain drying systems

These are stand alone units that are specifically designed to force hot air through damp grain. It’s a lower risk approach to making sure grain doesn’t spoil and gives farmers more control with options for speeding up the drying process or allowing for drying at higher rates.

Typically grain dryers use natural gas or propane for thermal energy and electricity for fan power and system grain flow. Because they use higher heat and are more time-efficient, they also use more energy and can be costly to run.

They can be batch or continuous flow.

Batch – A predetermined quantity is placed in a container and hot air is blown into the container to the grain in cycles. Each batch is dried to the specified moisture content and then released, while the process is repeated with the next batch.
Continuous flow – Wet grain enters the dryer in a steady stream and cycles through the dryer, exiting as cool dry product.

The goal at the end of the day is to get the grain dry so it can be stored without spoiling. It’s a continual balancing act that requires careful monitoring and management of moisture levels to protect the grain and produce a high-quality product.