Open image in new window Fig. 4 3D image of a pressure-regulating station.
A process model can be constructed (Fig. 5) based on controller set pressures of the pressure-regulating station (Table 1).
For the case of the pressure-regulating station, 'manually close the emergency shutdown valve inside the station' is a representative action in the case of a gas release.
In this study, the pressure-regulating station near the residential area is chosen as the target process for implementing our model as it has a high risk of fire and explosion accident (Fig. 4).
In this study, the worst-case scenario is performed among three main scenarios in order to evaluate our model linking the process and accident simulation for operator training system in the pressure-regulating station.
In the center is a process flow diagram (PFD) of the pressure-regulating station, on the left are process upsets and accident scenarios, at the top are controllers and process variable information, on the right is a single variable chart, and at the bottom is the gas concentration of dispersed gas.
A case study deals with a natural gas pressure-regulating station in South Korea and evaluates the applicability of our model to practical operator training by generating process upsets and accident scenarios, constructing dynamic process and accident simulation models, and developing a demonstration program.
Figure 7 indicates the accident simulation model of the pressure-regulating station in FLACS, and Fig. 8 indicates the gas concentration (red: 1.0, green: 0.5, blue: 0.0 m3/m3) from 10 to 600 s at the height of ventilation when a gas releases for 5 min near the pressure recorder due to the second pressure rise (202.6 kPa).
Open image in new window Fig. 5 Process model of the pressure-regulating station Table 1 Controller set pressure Controller Set pressure, kPa Failure alarm Lower limit 1.2 Upper limit 3.2 SSV-1 (main line) Relief valve 3.6 4.0 SSV-2 (preliminary line) 4.4 Open image in new window Fig. 6 Controller operation (top main valve and bottom SSV).
Dispersed gas concentration results at the bottom are only activated in the worst case among three scenarios, which shows the 3D geometry of the pressure-regulating station, gas concentration at the height of ventilation in the form of the univariate chart, and 2D and 3D image.
