Energy Saving in Grain Drying Using Frequency Converters
Drying grain is a complex process that requires significant electrical energy costs. Therefore, professionals in this field are always looking for ways to reduce energy consumption per ton of dried grain. Frequency converters can greatly assist in this. They provide a return on investment in less than 2000 hours of operation, which corresponds to about three months, well within one season.
Structure of the Grain Drying Complex
A typical scheme of a grain drying complex consists of several key components:
- Loading pit - the initial stage where grain arrives for processing.
- Conveyor - moves grain to the bucket elevator.
- Bucket elevator - lifts grain upward for further processing.
- Seed cleaning machine - removes debris and impurities from the grain.
- Intermediate bunker - holds cleaned grain ready for drying.
- Drying unit - performs the main drying process.
- Unloading screw - cools the grain using fans.
- Final conveyors - transport grain to storage, bins, or directly into trucks and rail cars.
Those planning to purchase an elevator in parts usually base their calculations on productivity reserves. If it is expected that the complex will process 100 tons per day, the transport components are designed for 150 tons per day, allowing for future capacity expansion.
Energy Savings Through Frequency Converters
One of the main advantages of using frequency converters is the ability to regulate the unloading speed of grain, which in turn affects the overall efficiency of the complex. Proper regulation of this speed allows for a reduction in energy consumption while ensuring the required moisture level of the grain.
Regarding unloading, optimizing this process allows for significant energy savings. By reducing the productivity, it is possible to save costs while maintaining the appropriate quality of the grain.
Changing Processing Speed to Increase Efficiency
The parameters for transporting grain and the speed of its loading also need to be adapted depending on the chosen productivity. It is important to simultaneously reduce energy consumption and increase the efficiency coefficient (EC) of the motors to 96-98%. Reducing the power supply voltage can provide energy savings of up to 30% without a loss of power.
On the cleaning fan, if it is properly sized, there is also an opportunity to save electricity. With a 35-40% reduction in fan productivity, the power consumed can be halved.
Cooling Module Savings
The cooling module for grain after drying also requires flexibility in productivity to adapt to external temperatures. This affects the quality of the finished product.
According to data obtained from our clients, the payback period for investments in a frequency converter was less than 90 working days. Here are the average energy savings figures:
- On the bucket elevator - 18%
- On conveyors - 27%
- On the unloading module - 37%
- On the cleaning machine - 32%
- On the grain cooler - 35%
Considering a rate of 1.92 hryvnias per kWh, the payback is less than 2000 hours (90 working days). For example, for a cooler motor rated at 5.5 kW, the savings per hour amount to 3.7 UAH. Over 2000 hours of operation, this totals 7400 UAH, which completely covers the costs of purchasing the frequency converter in just three months.