In a complete BellaEx steam-flaked corn production line, the flaking mill is usually followed by a long horizontal dryer-cooler, along with fans, a heat exchanger and the associated ductwork.
So how does this horizontal dryer-cooler actually work? How does the freshly flaked corn enter the machine and move through it? And what roles do hot air and cooling air play?
If you're comparing different production line designs, you may also notice that some projects use a single-layer dryer-cooler, while others use double-layer or multi-layer designs. How do these configurations work, and why might one be chosen over another?
Let's go through these questions one by one, starting with what happens when the corn flakes enter the machine.
How Do Corn Flakes Move Through the Dryer-Cooler?
After steam conditioning and flaking, the corn moves into the drying and cooling section.
In BellaEx's horizontal dryer-cooler system, the flakes first pass through a distribution device that spreads them across the inlet area of the machine.
The purpose is to distribute the flakes as evenly as possible, rather than letting too much material pile up in one place. This helps air pass through the layer of corn flakes, allowing for more even drying and cooling.
Are the corn flakes carried on a moving mesh belt, or does the machine use another conveying method?
In the BellaEx horizontal dryer-cooler design discussed here, the conveying system uses chains and square-tube pusher bars.
As the chains move, they drive the pusher bars forward, gradually pushing the corn flakes along the machine. Perforated plates beneath the material allow drying and cooling air to pass through the bed of flakes.
In other words, two processes are taking place inside the machine at the same time.
The conveying system moves the corn flakes forward, while air passes through the material bed to dry or cool them.
As the flakes move along the machine, they pass through the drying zone and then the cooling zone. Finally, they leave through the outlet and move on to finished-product conveying, storage or packaging.
Caption: The diagram shows the path of corn flakes from the inlet and distribution device through the chain-driven conveying system, drying zone and cooling zone to the outlet. It also identifies the perforated plates beneath the material.
How Do Hot Air and Cooling Air Dry and Cool the Corn Flakes?
As the corn flakes move through the machine, they pass through two stages: drying and cooling.
The drying zone mainly removes some of the moisture from the corn flakes.
Take a system that uses a steam-heated heat exchanger as an example. Steam supplies heat to the exchanger, which warms the air before fans deliver it into the drying zone.
As the hot air passes through the layer of corn flakes, it transfers heat to the material and causes some of the moisture to evaporate. The moisture-laden air is then removed through the exhaust system.
As the flakes move through the drying zone, their moisture content gradually decreases.
The cooling zone mainly lowers the temperature of the corn flakes.
The flakes are still warm after drying. In the cooling zone, cooler air passes through the material bed and carries away some of the heat, gradually lowering the flakes' temperature.
Together, these two stages help bring the moisture content and temperature of the flakes closer to the conditions required for storage, packaging or transport.
Caption: The diagram shows hot air entering the drying zone, moisture-laden air leaving through the exhaust system, and cooling air entering the cooling zone, alongside the direction of material movement. The actual airflow directions and duct arrangement depend on the equipment configuration.
Drying performance doesn't depend on hot-air temperature alone.
Air temperature, airflow, the thickness of the corn flake bed and the time the material spends inside the machine all need to be considered together.
For example, if the flakes move through the drying zone too quickly, there may not be enough time to remove the required moisture. But simply raising the hot-air temperature doesn't necessarily give better results.
That's why the hot-air system and material conveying system need to be configured and adjusted according to the actual process requirements.
What Do We Consider When Configuring a Dryer-Cooler?
When configuring a dryer-cooler, BellaEx typically considers the hourly material throughput, inlet and outlet moisture content, target outlet temperature, required residence time, available heat source and plant space.
These factors affect the machine's dimensions, the arrangement of the drying and cooling zones, and the heating and airflow systems.
One important calculation is how many kilograms of water need to be evaporated from the corn flakes each hour.
Let's look at a simple example.
Suppose 10,000 kg of wet corn flakes enter the dryer each hour, with an inlet moisture content of 18% and a target outlet moisture content of 14%. Both values are on a wet basis, and we assume no loss of dry matter.
The water evaporation rate can be calculated as follows:
Water evaporation rate (kg/h) = Inlet material flow × (Inlet moisture − Outlet moisture) ÷ (1 − Outlet moisture)
Using the moisture values as decimals:
10,000 × (0.18 − 0.14) ÷ (1 − 0.14) ≈ 465 kg/h
Under these assumed conditions, the dryer would need to evaporate approximately 465 kg of water per hour.
This illustrates an important point: even when two production lines handle the same amount of material per hour, different inlet and outlet moisture requirements can result in different drying loads.
That's why our engineers consider the required water evaporation rate, residence time, heating capacity and airflow together when configuring a dryer-cooler.
Why Do Some Projects Use Single-Layer Dryers While Others Use Double-Layer or Multi-Layer Designs?
If you're comparing production line proposals from different manufacturers, you may notice that their dryer-coolers don't all have the same structure.
Some use a single-layer design, while others use double-layer or multi-layer arrangements.
One of the most noticeable differences is the path the material follows inside the machine and how much space the equipment occupies.
In a single-layer horizontal dryer-cooler, the corn flakes generally move forward along one main horizontal conveying path, passing through the required treatment zones.
If a longer residence time is needed, the machine may require a longer effective conveying path, which can take up more horizontal space.
In a double-layer or multi-layer dryer, the material can move through different levels, allowing a longer conveying path within a smaller horizontal footprint.
However, multi-layer designs also need to account for how the material moves from one level to another, along with the machine's height, internal cleaning and maintenance access.
Does that mean a single-layer dryer is always better than a multi-layer dryer?
Not necessarily.
Beyond the machine's structure, we also need to consider the line's target capacity, drying requirements, available building length and height, and how the equipment connects to the rest of the production line.
For example, with steam-flaked corn, we want to avoid unnecessary flake breakage during conveying and transfer. Site conditions and process requirements can also vary considerably from one project to another. If your plant doesn't have enough space for a long horizontal dryer, a double-layer design may be worth considering.
That's why, at BellaEx, whether we use a single-layer or multi-layer design, we select a suitable dryer-cooler configuration based on the actual production needs and site conditions, rather than judging a design simply by the number of layers it has.
Discuss Your Drying & Cooling Requirements with BellaEx
If you're planning a steam-flaked corn production line with a drying and cooling system, you can start by sharing your target capacity, raw material and finished-product moisture requirements, available heat source and plant space.
If you already have a production line or related equipment, you can also send us the existing machine models, dimensions and process information.
BellaEx can help you discuss the dryer-cooler's structure, dimensions, heating and airflow arrangements, and how it connects with the upstream and downstream equipment based on your production needs and site conditions.
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To learn more about BellaEx's horizontal drying and cooling equipment, visit our Horizontal Dryer-Cooler product page.
If you're planning a complete steam-flaked corn production line, you can also explore our Steam-Flaked Corn Production Line solution page.
