Research On Ultrasonic Measurement Of Mass Level In Coal Ball Mill And Generic Optimization Method Of Pulverizer System Operation

Security and high efficiency is always the target of electric power production. The stress of price competition forces electric power manufacturers to tap the latent power of the units to improve efficiency, and reduce the staff to cut cost down. As main energy consumer in thermal power plants, performance of the ball mill pulverizer system directly impacts the whole power plant's security and economy.As a matter of fact, it is hardly possible to accurately measure mass level in coal ball mill, and pulverizer system operation could hardly be optimized to be harmonious. In a long period of time, these problems disturb the automatization control of ball mill pulverizer system of thermal power plants. Aiming at the solution of the problems, this paper researches the ultrasonic non-contact measurement of the mass level in coal ball mill and optimization computation based on generic algorithm. Sevral methods are applied and combined in this paper, including dynamic simulation based on theoretical analysis, physical experiment and field test in power plants. The work presented above could provide technical preparation for the operation optimization of ball mill pulverizer system of thermal power plants.In this dissertation, following works are completed.i. Based on the wave theory, a single-layer ultrasonic transmiting model and a solid particulate load model are built. Simulation tests are processed on the models. By comparison between the single-layer model and the two-layer model, the methods of identifying coal load in ball mill could be achieved. One method is measuring the phase velocity. The coal load could be identified according to the difference of phase velocity. And then another, analyzing the energy of received signal. The coal load could be identified by the energy intensity. These two methods could be complementary and validated with each other.ii. Experiments in lab and field tests are performed to research non-contact ultrasonic measurement method of coal ball mill and its implementary project. The results of experiments in lab show that, according to the received signal's characteristic parameters (wave amplitude of peak, signal level) and wave form (time domain, frequency spectrum and power spectrum estimate), it can be identified if there is coal load on solid surface. Field tests proved the conclusion of simulations and experiments in lab.