Accurate Incineration Control: An Interesting and Important Engineering Challenge

This paper introduces some interesting concepts in incinerator control. It points out the fact that present day control hardware can be applied in im­ proving incinerator performance. We believe that while the hardware is satisfactory for this purpose, differences in performance between fossil fuel boilers, where these controls have been utilized and incinerators will limit their application in the sug­ gested incinerator control loops. An automatic controller is a device which measures a process variable, compares its value to that of a desired value (set point) and initiates cor­ recti ve action when the two values are not equal. The set point value is a human judgment fed in by the process operator and is based on his knowledge of the effect of this variable on the overall process. It follows then, that the automatic controller can satisfactorily affect the process operation only when: 1. The measurement of controlled variable is a true index of the actual value of that variable. 2. The operator's knowledge of the process enabled him to program a relationship between set­ point and variable which will ensure that the cor­ rective action taken by the controller will produce the correct response in the process performance. The various control loops proposed by the author will meet the first criteria with presently available hardware. As pointed out in the paper, however, location of sampling points is critical in obtaining valid measurements. It is in the area of the second criteria that problems will be experienced in applying these con­ trol schemes to the refuse incineration process. In general, the secondary or auxiliary control loops such as furnace pressure, drum level and spray chamber temperature will operate satisfactorily as proposed in most applications. We believe that drum level can be better controlled in a much wider range