Industrial process plants in Japan have been seeking for the highest productivity and optimization of their processes, same with any process plant all over the world. These plants were renovated and expanded as time passed for the purpose, the plants themselves became complicated and troublesome as a result. Few years ago, severe process plant incidents occurred in Japan. The most probable causes of these severe incidents are out of âincorrect judgement and operationâ and âshortage of prediction for technical aspectsâ during exceptional manual work that has been done by incidents. Understanding the hazardous situation by risk analysis and designing safety measures utilizing a SIS (Safety Instrumented System) are important and effective for resolving âincorrect judgement and operationâ and âshortage of prediction of technical aspectâ. Safety measure includes human intervention via SIS man-machine interface which showing alarm, event, and process data.
The safety measure and its function are developed on the desk by brainstorming or so-called âhazard and operability study (HAZOP).â The verification of the safety function hardware could be established by reliability based analysis, SIL calculation in other word. However, the verification of safety logic is the issue because it has only been verified âon the deskâ. Especially the determination of the criteria for the emergency shutdown is the most important, but it is not possible to be confirmed with "try and error" on a running plant. Safer HMI design for operatorsâ quick and appropriate response is also important. A âDynamic Plant Simulatorâ can precisely simulate behaviors of the real process by visualizing how a hazard is diffused at various stages of a chemical reaction. And combination of DCS/SIS/HMI simulator with âDynamic Plant Simulatorâ, safety logic design is optimized about trip point and alarm threshold, and HMI design is modified safer manner. The effective result of application of âcyber modelâ to a vinyl acetate monomer (VAM) plant will be explained.
