抄録
When pulverized coal boiler is automatically controlled, it is very important to detect the coal level of ball mill. By using a noise level meter that has a certain frequency characteristic, hoever, the coal level can be found out exactly. Furthermore, by applying this signal to the coal feeder, the ball mill system can be automatically controlled. It can be controlled more exactly when ripple of wave form per revolution of the ball mill is used. Fig. 10 shows the simple on-off system, in case of which cycling certainly occurs as well known. It however has been modified by the authors as shown in Fig. 14 and B sin ω0t is called a forced oscillation. By choosing B and ω0 properly, it can be stabilized without causing any cycling. Mr. R. OLDENBURGER has shown an interesting analysis about the control of saturation, but the authors, by using Bode chart, analysed the on-off controller that has a dead zone. They calculated the transfer function of on-off controller in case the forced oscillation was applied and, as its result, gave why the system is stabilized and probable value of B and ω0. Then, the above mentioned analysis was confirmed with analog computer.
