The chemical process
industry has become the backbone of the global
economy. The complexities of chemical process systems have been increased
in the last two decades due to online sensor technology, plant-wide
automation, and computerized measurement devices. Principal component
analysis (PCA) and signed directed graph (SDG) are some of the quantitative
and qualitative monitoring techniques that have been widely applied
for chemical fault detection and diagnosis (FDD). The conventional
PCA-SDG algorithm is a single-scale FDD representation origin, which
cannot effectively solve multiple FDD representation origins. The
multiscale PCA-SDG wavelet-based monitoring technique has potential
because it easily distinguishes between deterministic and stochastic
characteristics. This study uses multiscale PCA-SDG to detect, diagnose
the root cause and identify the fault propagation path. The proposed
method is applied to a continuous stirred tank reactor system to validate
its effectiveness. The propagation route of most process failures
is detected, identified, and diagnosed, which is well-aligned with
the fault description, demonstrating a satisfactory performance of
the suggested technique for monitoring the process failures.