Decoupling Consistency and Level Control Around a Continuous Pulper: Part1

Around continuous pulpers in the waste plant, multiple feedback loops am used to control pulping consistency and pulper level. Inherent variations in wastepaper or pulp bale flow rate, pulper process dynamics, and control loop interactions, can cause significant consistency variations within the continuous pulping system. A dynamic computer simulation model of this system has been developed. Using the model the relative effects of process variables, like bale size, frequency and defibering time constants and control parameters like controller gain am explored. Large bales which quickly defiber are shown to have the most dramatic effect on consistency fluctuations. Coupled interaction between consistency and level is shown to be negligible with respect to level but significant with respect to consistency. After a moderate level disturbance the system is shown to take several hours to damp consistency fluctuations.