After an incident at a gas processing plant, its processes needed to be examined and analyzed to determine what factors may have led to the occurrence. The incident centered around the loss of liquid level and breakthrough of a high-pressure two-phase mixture into low pressure equipment (HP/LP Interface) leading to cold temperatures and subsequent brittle failure of a vessel. The process was so complex that careful study by many experts was unable to clearly identify the cause-and-effect of each of the events and actions.
ioMosaic created a computer simulation using Process Safety Office® SuperChems™, a detailed dynamic simulator, to elucidate the connections between the events and actions taken and the final incident. The events and actions to be simulated included:
Feed rate changes are shown in Figure 1. The model outputs (thick lines) are compared to the actual measured flows (thin lines). To match the measured flows, controllers were set using the process simulators event scheduler.
Identifying roots causes is an important part of any incident investigation. The validated dynamic model enabled the case team to reliably and quickly confirm or rule out specific scenarios and/or combinations of operator actions that could have led to the incident. Now the company was equipped with data that provided invaluable insight about the incident to help them make more informed safety decisions.