Dynamics mode results for the C1 example simulation

The extended simulation model generates the dynamic mode results. We set up the Increase Methanol Concentration scenario for dynamic analysis. This scenario increases the feed methanol concentration from 29% to 33% by mole.

When the methanol concentration increases, the change in density causes the feed flow rate to initially drop before stabilizing back at the setpoint set by the feed flow controller (FC1). The temperature across the column drops and the temperature controller at stage 9 (TC1) increases the hot steam supply, as shown in the following figure.

Figure 4: Stage 9 temperature and steam supply

The column pressure increases due to the increased reboiler duty. More overheads are condensed and the reflux drum level increases. The level controller at the drum (LC1) increases the distillate rate after an initial oscillation, as shown in the following figure.

Figure 5: Distillate rate and reflux drum level

At the same time, the level controller at the sump (LC2) lowers the bottom product rate after an initial oscillation because the increased boilup reduces the amount of liquid reaching the sump, as shown in the following figure.

Figure 6: Bottoms rate and sump level

The changes in feed quality do not have a significant impact on the product purity. The system maintains the quality of methanol in the distillate at 95.8% instead of the design requirement of 96%, as shown in the following figure. Note that we have significantly adjusted the scales to show the disturbance in the product quality.

Figure 7: Product compositions

In addition to the Increase Methanol Concentration scenario, we set up another scenario that runs dynamics for 20 minutes to study any further changes. The following figure shows the list of scenarios in this simulation.