Reliability-Aware Inferential Measurement for MAPD Hydrogenation Control
Selective hydrogenation units remove trace methylacetylene and propadiene (MAPD) from a propylene stream. The more selective way to dose hydrogen is to ratio it against the measured inlet MAPD concentration. That strategy requires a continuous and trustworthy MAPD signal at every control interval, and the online gas chromatograph (GC) that provides it is intermittent and occasionally unreliable. A soft sensor intended for closed-loop use cannot be judged as a standalone predictor. Low aggregate error and near-nominal interval coverage can still hide local reliability loss during operating-state transitions, which is exactly when a controller can least afford a bad measurement. The soft sensor is therefore treated as part of a reliability-aware measurement layer that decides, at each step, whether to trust the analyzer, rely on the model, or route the controller to a conservative fallback. ...