A gas processing plant experienced an incident and reached out to ioMosaic to examine and analyze their processes to identify and help determine factors that may have led to the incident. To study the events that lead to an incident in a gas processing plant, a dynamic computer simulation was created by ioMosaic for an entire process. 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. 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.
A computer simulation was created by ioMosaic to try 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, pump outages and restarts, and controller set point changes. 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. Thereby, the company was equipped with data that provided invaluable insight about the incident to help make more informed safety decisions.