I. Air Conditioning Load
Office buildings, shopping malls, supermarkets, and factories all have central air conditioning systems, which consume a significant amount of electricity during the summer peak season. In hot weather, air conditioning accounts for over 40% of peak electricity consumption in Beijing, Shanghai, and Shenzhen. Therefore, using inverters to drive the chilled water pumps and fans in air conditioning systems is an excellent energy-saving technology. Currently, many companies nationwide specialize in air conditioning energy saving, with inverter speed control being their primary technology.
II. Crusher-type loads
Crushers and ball mills are widely used in metallurgy, mining, and building materials industries, and frequency conversion has shown significant effects on these types of loads.
III. Large kilns and calcining furnaces
Previously, most large industrial rotary kilns (converters) in metallurgy, building materials, and caustic soda industries used DC motors, commutator motors, slip-ring motors, cascade speed regulation, or medium-frequency generator speed regulation. However, due to the presence of slip rings or low efficiency of these methods, many units have adopted frequency converter control in recent years, with excellent results.
IV. Compressor-type loads
Compressors are also a widely used type of load. Low-pressure compressors are commonly used in various industrial sectors, while high-pressure, large-capacity compressors are widely used in steel (such as oxygen generators), mining, fertilizer, and ethylene industries. The use of variable frequency speed control brings advantages such as low starting current, energy saving, and optimized equipment lifespan.
V. Rolling Mill Loads
In the metallurgical industry, large rolling mills used AC-AC frequency converters in the past, but in recent years they have adopted AC-DC-AC frequency converters. The AC conversion of rolling mills has become a trend, especially in light-load rolling mills. For example, the multi-stand aluminum rolling mill of Ningxia National Aluminum Products Factory uses a general-purpose frequency converter to meet the requirements of low-frequency load start-up, synchronous operation between stands, constant tension control, and simple and reliable operation.
VI. Winch type loads
Variable frequency speed control (VFD) is used for winch-type loads, ensuring stability and reliability. Blast furnace winches in ironworks are the primary equipment for conveying raw materials in ironmaking. They require smooth starting and braking, uniform acceleration and deceleration, and high reliability. Previously, cascade, DC, or rotor resistance speed control methods were commonly used, resulting in low efficiency and poor reliability. Replacing these methods with AC VFDs achieves ideal results.
VII. Converter-type loads
For converter-type loads, using AC frequency converters to replace DC units is simple, reliable, and provides stable operation.
8. Roller conveyor loads
Roller conveyor loads are mostly used in the steel and metallurgical industry. Using AC motor frequency conversion control can improve the reliability and stability of the equipment.
