The “heart” of a grain dryer and its common failure phenomena
Release date:
2023-12-20
A grain dryer consists of four main components: a heat source, a fan, a control system, and the drying tower body. The fan is the heart of the grain dryer—it primarily delivers heat into the drying layer, enabling convective heat transfer between the hot air and the grain, thereby causing moisture to vaporize and separate from the grain. Consequently, the fan’s performance parameters determine the dryer’s drying efficiency, energy consumption, and the quality of the dried grain. The fan significantly influences the overall energy consumption for conveying and distributing within the drying system, making it a critically important component of the grain dryer.
A grain dryer consists of four main components: a heat source, a fan, a control system, and the drying tower body. The fan is the heart of the grain dryer—it primarily delivers heat into the drying layer, enabling convective heat transfer between the hot air and the grain, thereby causing moisture to vaporize and separate from the grain. Consequently, the fan’s performance parameters directly determine the dryer’s drying efficiency, energy consumption, and the quality of the dried grain. The fan significantly influences the overall energy consumption for conveying and distributing within the drying system, making it an extremely critical component of the grain dryer.
It is worth noting that, according to years of fan testing conducted by the National Center for Quality Supervision and Inspection of Relevant Equipment, many fans exhibit problems even under rated operating conditions. Consequently, during the drying process in grain dryers, malfunctions such as high-temperature tripping of the fans are frequently encountered. To address the losses caused by fan failures under normal operating conditions in grain dryers, we have compiled the following practical experiences for your reference.
1. When the grain dryer equipment system is brought into operation, the fans should be started up sequentially. At the initial stage of operation, the vibration at the bearing area is minimal. However, as operating time increases, dust particles will gradually and unevenly accumulate on the impeller, progressively disrupting the fan’s dynamic balance and causing the bearing vibration to steadily increase. Once the vibration reaches the fan’s allowable limit of 11 mm/s, the fan must be stopped immediately for maintenance (to remove accumulated dust and re-balance the rotor). At this point, the situation has become extremely dangerous, and users must absolutely not continue operating the fan under these conditions.
2. Under normal conditions, the bearing temperature of the fan should be ≤70℃. If the temperature rises to 70℃, the electrical control cabinet should sound an alarm. At this point, you should identify the cause. First, check whether the cooling water is flowing properly and whether the bearing oil level is normal.
3. During the operation, startup, or shutdown of the fan, if any abnormal conditions are detected (such as unusual noises, abnormal vibrations, or abnormal temperature rise), an immediate inspection should be conducted. Any minor faults identified during the inspection should be promptly investigated and eliminated. If a major fault is discovered (such as severe fan vibration, impact noises, or a sharp rise in bearing temperature), the fan should be stopped immediately for inspection.
Four: Master the correct method for opening the air damper on the fan, as malfunctions caused by careless operation of the air damper are frequently observed.
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The grain dryer—a guardian safeguarding the quality of food grains.
The primary function of a grain dryer is to utilize its internal hot-air circulation system to evaporate and remove moisture from the grain. During this process, the machine effectively preserves the grain’s quality—such as its color, flavor, and nutritional value—ensuring its long-term storage and usability. Moreover, using a grain dryer can significantly enhance the efficiency of grain processing, saving substantial labor and time costs.
Grain dryer fault inspection and troubleshooting
If the moisture content of the dried material exceeds the specified value, the solution is to control the drying machine’s production capacity by increasing or decreasing the heat supply. The swinging motion of the roller ring during the cylinder’s rotation is caused by insufficient clamping on the concave joint side of the roller ring. To eliminate this issue, use shims to ensure that the roller ring and the concave joint are evenly aligned and properly clamped, avoiding excessive tightness that could easily lead to accidents.
How to operate and maintain a grain dryer
The drying efficiency of a dryer largely depends on the quality of its combustion chamber. Therefore, during dryer operation, special attention must be paid to the combustion chamber, the blower, and the dust collection and extraction equipment. One hour before starting the dryer, light the furnace and thoroughly inspect all auxiliary equipment—including all transmission components and support structures of the dryer—to ensure that they are securely fastened, functioning properly, smoothly operating, and reliable before commencing operation.
Performance characteristics of grain dryers
The grain dryer features a simple structure, compact size, and convenient operation. It requires no auxiliary equipment, making it easy to transport and move. The grain dryer uses hot air as the drying medium and employs a recirculating drying process, ensuring even and thorough heating and moisture removal, resulting in high-quality dried grains. This grain dryer uses coal, rice husks, or straw as fuel; after combustion and heat exchange, it produces clean, hot air that does not contaminate the grains being dried.
The working principle of a grain dryer
The hot-air drying oven features a spiral heating system that generates a large volume of hot air in a short time. Through high-temperature treatment, it effectively kills insect eggs and completely eliminates discoloration that may occur during the drying process. The oven’s inner chamber is equipped with metal aluminum wall panels, insulated with silicone rubber cotton, and finished with corrugated color-coated steel sheets or aluminum alloy outer panels. Inside the oven, digital control and monitoring systems ensure precise management of air circulation, humidification, and temperature adjustment.
The “heart” of a grain dryer and its common failure phenomena
A grain dryer consists of four main components: a heat source, a fan, a control system, and the drying tower body. The fan is the heart of the grain dryer—it primarily delivers heat into the drying layer, enabling convective heat transfer between the hot air and the grain, thereby causing moisture to vaporize and separate from the grain. Consequently, the fan’s performance parameters determine the dryer’s drying efficiency, energy consumption, and the quality of the dried grain. The fan significantly influences the overall energy consumption for conveying and distributing within the drying system, making it a critically important component of the grain dryer.