1.
Energy saving using electric motors. From the point of view of energy saving and environmental protection, high-efficiency motors are the direction of development not only for cement factories, but also for the entire industry in China.
The cement industry is one of the six largest consumers of electricity and is one of the main applications for small and medium-sized motors: the higher the consumption, the greater the savings potential. The engines of the main workshops - raw material grinding, rotary kilns and cement grinding - usually operate continuously 24 hours, for a long time and at a relatively stable load.
This favors the introduction of highly efficient engines. According to GB18613-2006, there are three energy efficiency classes: the first is ultra-efficient, the second is high-efficiency, and the third is conventional motors.
Optimized design and quality materials enable high-efficiency motors to reduce energy consumption by approximately 20% on average, and ultra-efficient motors to reduce energy consumption by more than 30% compared to conventional motors, providing savings throughout the entire production cycle. Although the price is 15-30% higher, the additional investment usually pays for itself in 1-3 years.
Therefore, the use of high-quality, highly efficient energy-saving engines in cement plants with long-term continuous operation and high load corresponds to the energy saving policy and is a necessary and practically feasible solution for the development of the enterprise.
2. Rational choice of engine power
For historical reasons, in practice the load power is often significantly lower than the motor power, causing many motors to operate inefficiently.
For example, the average efficiency of fan, pump and compressor systems with high power consumption is about 50%. When designing, repeatedly adding power reserves for a reliable drive easily leads to overestimated power and low efficiency.
Sometimes the inverter is used mainly for speed control, and the motor runs for a long time at a low frequency with low efficiency - this is also a manifestation of excessive power. Typically, the most efficient operation is achieved with a load factor of 0.7–0.85.
Too much or too little load reduces efficiency and can damage the engine, increasing repair and maintenance costs. At one cement plant, when calculating based on the technologically specified engine power, the theoretical load of the selected transformer was about 0.75, but in fact it was below 0.6.
Such a serious overestimation of power wastes equipment resources and electricity. With a shortage of funds at some cement plants, this increases financial pressure and deprives the enterprise of development opportunities.
A rational choice of engine power corresponds to the energy saving policy, reduces the financial burden and creates an economic basis and conditions for further work and development. This task still requires significant effort.
