Dynamics mode for the GG5 example simulation

During Dynamics mode, the inlet and outlet valves, XV1 and XV4, close and the drums are isentropically depressurized through valve XV5 to calculate the fluid temperature. To accurately calculate the metal temperatures across the length of the pipe, we use a rigorous pipe with the PipeInAir heat transfer method that calculates the heat transfer from the fluid to the pipe wall and from the pipe wall to the ambient air.

The rigorous pipe calculates the temperature along the length of the pipe. This 20-inch pipe has 5 segments of equal length. We model the pressure drop through the entire pipe by using the length of each pipe segment to calculate the correct fluid pressure.

We set the following conditions for the rigorous pipe:

• It calculates the heat transfer from the fluid to the pipe wall.

• It uses the PipeInAir setting to calculate the heat transfer from the pipe metal to the ambient air.

• It uses the Beggs and Brill Moody High Velocity (BBMHV) calculations.

• It uses average conditions of pressure and temperature for each segment.

• The total length of the pipe is 625 m.

We automate the depressurization of the drums by using a Scenario, as shown in the following figure. In this Scenario, after one minute, we isolate the two drums by closing the feed valve XV1 and the product valve XV4 while opening the vent valve XV5 to the relief pipe. The simulation then runs until it reaches 20 minutes.