What equipment is needed for drying grains

Grain drying is a crucial step to ensure the safety of grain storage and reduce moldy losses. The required equipment should be selected based on the type of grain (such as wheat, corn, rice, etc.), drying scale (small batch for households, medium batch for farms, large grain depots), and drying process (such as co-current flow, counter-current flow, mixed flow, etc.). The following is the classification and specific introduction of commonly used equipment in the grain drying process:

I. Core Drying Equipment

This type of equipment is the main body for grain drying, directly achieving moisture evaporation. According to its working principle and structure, it can be classified into the following categories:

#### 1. Continuous grain dryer (suitable for medium and large scale)

- ** Co-current dryer ** : The hot air flows in the same direction as the grain. The high-temperature hot air first comes into contact with the wet grain, resulting in high drying efficiency. It is suitable for high-moisture grains (such as corn with an initial moisture content of over 25%), but the uniformity of drying from top to bottom of the grain layer is slightly worse.

Counter-flow dryer: The hot air flows in the opposite direction to the grain. The low-temperature hot air comes into contact with the grain to be dried, ensuring uniform drying and maintaining good grain quality. However, it has relatively high energy consumption and is suitable for grains with high quality requirements (such as rice).

- ** Mixed-flow dryer ** : Combining the features of co-current and counter-current flow, hot air passes through the grain layers multiple times, ensuring uniform drying and moderate energy consumption. It is currently a widely used type, suitable for various grains and different moisture contents.

- ** Circulating dryer ** : Grains are dried in a circulating manner inside the machine until the target moisture content is reached. It is suitable for small and medium-sized enterprises (such as farmers and small cooperatives), with simple operation but relatively low efficiency.

#### 2. batch dryer (batch type, suitable for small batches)

Such as box-type dryers and drum dryers, a fixed amount of grain is loaded at one time. After drying, it is taken out. They are suitable for families or small farms. The equipment cost is low but the output is small.

Ii. Auxiliary pretreatment equipment

Before the grains enter the dryer, they need to undergo pre-treatment such as cleaning and grading to prevent impurities from affecting the drying efficiency or damaging the equipment.

- ** Grain cleaning screen ** : It removes impurities such as straw, soil, stones, and weeds from grains through vibration, air separation, and other methods. Common types include vibrating screens, cylindrical screens, and specific gravity classification screens.

- ** Lifting and conveying equipment ** : Transport the cleaned grains to the dryer, including bucket elevators (vertical conveying), belt conveyors (horizontal or inclined conveying), screw conveyors (suitable for small particles and short-distance conveying), etc.

- ** Stone Remover ** : Specifically designed to remove stones with a specific gravity close to that of the grain, improving the quality of the grain and preventing wear and tear on the internal components of the dryer.

Iii. Heat Source Equipment

Drying requires a continuous supply of heat. The selection of heat source equipment directly affects the drying cost and environmental friendliness.

Coal-fired hot air furnaces: They have low costs but cause significant pollution. In some areas, their use has been restricted and they need to be equipped with desulfurization and dust removal devices.

- ** Oil/gas hot air furnace ** : Utilizing diesel, natural gas, etc., it features high thermal efficiency and low pollution, making it suitable for regions with high environmental protection requirements. However, the fuel cost is relatively high.

- ** Biomass hot Air furnace ** : Using biomass such as straw and sawdust as fuel, it is low-cost and environmentally friendly (belonging to renewable energy), suitable for agricultural production areas, but it is necessary to ensure a stable fuel supply.

- ** Electric heating equipment ** : Clean and easy to operate, but it has high energy consumption and cost. It is only suitable for small-batch drying or areas with abundant power resources.

- ** Solar dryer ** : It heats the air with solar energy, which is energy-saving and environmentally friendly. However, it is greatly affected by the weather and usually requires an auxiliary heat source (such as electricity or biomass).

Iv. Temperature Control and Monitoring Equipment

Ensure a stable drying process to prevent the grain from overheating and deteriorating or being underdried

- ** Temperature sensor ** : Real-time monitoring of the temperature of hot air and grain inside the dryer to prevent local overheating.

- ** Humidity sensor ** : Detects the humidity of the discharged exhaust gas to determine the degree of grain drying and facilitate the control of drying time.

- ** Intelligent Control System ** : By integrating temperature and humidity data through PLC (Programmable Logic Controller), it automatically adjusts the hot air temperature, grain flow rate, fan speed, etc., achieving automated drying and reducing manual intervention.

V. Subsequent processing equipment

The dried grains need further processing to facilitate storage or processing.

- ** Cooling equipment ** : Freshly dried grains have a relatively high temperature (usually 40-50℃), and direct storage is prone to mold. Therefore, they need to be cooled down to a temperature close to the ambient temperature through a cooling machine (such as a fluidized bed cooler).

- ** Grading Sieve ** : It grades the dried grains according to their particle size to meet different sales or processing requirements.

- ** Storage equipment ** : Such as grain silos and grain storage tanks, which are used for temporarily storing dried grains and need to have ventilation and moisture-proof functions.

Vi. Other auxiliary equipment

- ** Fan and Pipeline ** : The fan provides the power for hot air circulation, while the pipeline is used for hot air transportation and exhaust gas emission. The air volume and air pressure need to be matched according to the specifications of the dryer.

- ** Dust removal equipment ** : such as cyclone separators and bag filters, which handle the dust generated during the drying process, reduce air pollution and protect the health of operators.

- ** Emergency equipment ** : such as backup generators (to prevent power outages from affecting drying), fire-fighting equipment (for fire prevention requirements of heat sources such as fuel oil and coal).

In addition, the type of grain also needs to be taken into account (for example, for rice, it is necessary to avoid cracking at the waist and control the drying speed; Corn kernels are large, so it is necessary to ensure the penetration of hot air and local environmental protection policies (giving priority to low-pollution heat sources).