LAUSR

Abstract Degradation such as fouling has significant negative impact on the efficiency of process manufacturing. Creating transparency about degradation is essential in the operations of the plants. This paper focuses on the state estimation of fouling in a multipurpose batch process, and the problem is formulated using an industrial case study. Due to the lack of a good model of fouling, the state estimation is integrated with parameter estimation using the expectation maximization (EM) algorithm, where the variational approximation method is employed for the intermediate robust state estimation in the E-step. The proposed state estimation is applied in the case study, which demonstrates the efficacy of the estimation of a recipe-independent key performance indicator for the batch-to-batch fouling.