Need to know about grain dryers

It is vital to treat the crops in order to eliminate the excess moisture in order to avoid the development of fermentation and degenerative problems that might result from the moisture naturally present in the cereal.

The right grain shelf life is ensured by drying, and the cereal can be ready for further processing. When cereal is being harvested, its internal humidity can normally range from 17% to 40%, but the acceptable limit for sale is typically between 13 and 14%. This amount prevents crop degradation processes, ensuring a longer shelf life.

In order to protect the cereal from hazardous bacteria during storage and to reduce losses in product quality and useable or sellable amount, it is necessary to get the cereal to the lowest acceptable moisture level.

Given the importance that this process plays for the protection of the crop of many farmers, Mecmar has collected in this article all the important information on how a grain dryer works.

Dynamics of drying

The transfer of moisture from the grain's inside to its outside underlies the drying process. The grain is heated when hot, dry air contacts it, which causes the grain's moisture to evaporate and saturate the hot air.

In order to further simplify the complex drying dynamics, three main phases can be distinguished: the first phase involves extracting the water within the kernel and pushing it towards the outer wall; the second phase involves the evaporation of water by the air surrounding the kernels; and the third phase involves the expulsion of the humid air outside.

A uniform level of humidity exists inside the cereal when it is placed inside the grain dryer, but as the humidity outside the kernels starts to evaporate (due to the hot air the dryer blows out), the moisture inside the cereal starts to move toward the outside in order to restore the humidity balance. Therefore, all of the water on the surface is eliminated by taking advantage of a circulation of heated air and the product's porosity, followed by the water in the seed's core.

Air heating

The idea of moisture diffusion from the interior to the exterior is used by hot air grain dryers, and the constant airflow that laps the grain enables continual moisture removal.

The performance of the dryers may be maximized by maintaining a proper balance between the temperatures, air flows, pressures, and quantities of the product to be processed.

Grain dryers typically consist of:

a desiccant body that holds the cereal to dry, inside of which the excess water evaporates; a heat generator with an aeration system for producing the flow of hot air; a control panel with the control, regulation, and safety devices of the entire system; and any auxiliary equipment created for gathering, cleaning, weighing, and handling the product.

Air is separated between direct and indirect heating systems based on how it is heated. Systems that use direct heating blend combustion gases with outside air before introducing them into a mass of grains to dry. The burners must be adjusted at the proper temperature for these systems in order to burn the fuel correctly. The advantage of this type of heating is in the high performance, as all the heat produced by combustion is used for drying.

The combustion chamber and the collection of pipes that keep the combustion gases apart from the air used for drying are surrounded by the external air in indirect heating systems. The combustion byproducts in these types of heat producers are released into the environment, and the efficiency (and fuel savings) will increase as the exchange surfaces increase.

The final stage of drying is chilling, which is crucial for safe product storage. The techniques used to chill the grain varies based on the kind of dryer. In discontinuous dryers, cooling happens after drying and employs the same fan that blew hot air before; in continuous dryers, cooling happens in a designated part of the column or in a distinct cell. This stage is crucial for avoiding condensation, the growth of fungus, and the start of the fermentation process.

Types of dryer

In addition to the sort of heating, drying is the primary difference in how a dryer operates. Drying can be done continuously or in batches. Discontinuous dryers are so named because they completely dry a batch of cereal up to the machine's capacity before emptying the batch and preparing the drier for the subsequent batch of drying. These dryers may be moved around and placed wherever they are needed.

This kind of dryer is typically the best option for:

individuals with a couple tons of merchandise

individuals who must use continuous dryers to dry the heads and tails

people that think about drying for outsiders

those who wish to manage the drying of their crop while reducing the plant's fixed expenditures in comparison to fixed dryers

individuals who must dry many grain varieties.

Continuous dryers are so named because the drying of the grain occurs continuously, with the wet product being introduced from one end of the drier and the dried, cooled product being released from the other. The equipment often operates constantly for days or weeks while remaining stationary.

Because of these qualities, continuous dryers are the best option for:

Large drying facilities, which normally need to dry 240 tons or more per day.

Farms that need to dry a lot of grain every day, farms that need to dry a lot of the same kind of cereal, farms that have access to grain transport and storage facilities.