Abstract

Batch processes are commonly characterized by uneven trajectories due to the existence of batch-to-batch variations. The batch end-product quality is usually measured at the end of these uneven trajectories. It is necessary to align the time differences for both the measured trajectories and the batch end-product quality in order to implement statistical process monitoring and control schemes. Apart from synchronizing trajectories with variable lengths using an indicator variable or dynamic time warping, this paper proposes a novel approach to align uneven batch data by identifying short-window PCA&PLS models at first and then applying these identified models to extend shorter trajectories and predict future batch end-product quality. Furthermore, uneven batch data can also be aligned to be a specified batch length using moving window estimation. The proposed approach and its application to the control of batch end-product quality are demonstrated with a simulated example of fed-batch fermentation for penicillin production.

Highlights

  • Batch/semibatch processing plays a significant role in the production of low-volume, high valueadded products such as specialty polymers, pharmaceuticals and fine chemicals

  • Due to the complexity of batch processes, it is usually difficult to develop mechanistic models based on physicochemical principles

  • This paper has studied an approach to align uneven batch trajectories and the corresponding batch end-product quality values

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Summary

Introduction

Batch/semibatch processing plays a significant role in the production of low-volume, high valueadded products such as specialty polymers, pharmaceuticals and fine chemicals. An alternative approach is to predict the future batch end-product quality values at the synchronized batch duration time for shorter batches using a pre-determined model Such a model can be identified using the method proposed in [26], where a series of created pseudo batches are synchronized to their batch endpoints and a PLS model is identified from the synchronized pseudo batch data. As the synchronized pseudo batch data come from various windows of batch runs, the identified PLS model is essentially a moving-window PLS model It can be used for predicting future batch end-product quality as long as the process dynamics does not change for the time period that the moving windows cover.

Preliminaries
Uneven Batch Data Alignment Method
Case study
Findings
Conclusions

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