The problem of device redundancy in apparatus systems on the example of the propylene glycol production process: Problem redundancji urządzeń w systemach aparaturowych na przykładzie procesu produkcji glikolu propylenowego

Abstract

The article presents an analysis of device redundancy in apparatus systems, with particular emphasis on design, assembly, and integration issues in continuous industrial processes. The study highlights that in flow‑based production systems even short disturbances of technological parameters may lead to significant quality deviations, safety risks, and substantial economic losses. Ensuring high reliability therefore requires not only appropriate selection of equipment but also correct installation and configuration of redundant units that can maintain operational continuity. A detailed case study examines a propylene glycol production line in which a single hydrogen compressor constituted a critical single point of failure. The consequences of this configuration—including reactor instability, emergency shutdowns, complex restarts, and high downtime costs—are thoroughly discussed. To address these risks, an N+1 redundancy system was proposed, involving the installation of an additional compressor, a buffer vessel, and an automatic control‑switching algorithm. Technical evaluation includes hydrogen compression characteristics, multi‑stage operation with intercooling, and the impact of redundancy on process stability, while the economic assessment demonstrates a payback period of approximately 1.6 years. The results confirm that properly engineered and assembled redundancy significantly enhances functional safety, operational flexibility, and resistance to equipment failures. The article also points to the potential of hybrid simulation methods—combining discrete‑event, dynamic, and CFD modelling—as an advanced tool for evaluating redundancy strategies and supporting decision‑making in modern flow production systems and Industry 4.0 environments.