Process mode results for the A8 example simulation

The example simulation contains a variety of column profiles to help visualize the column and heat exchanger interactions. The following figure shows the temperature and flowrate profile for the low-pressure column. You can find similar profiles for the high-pressure and argon columns on the Canvas near each column. Markers on the figure show the location of each feed and vapor draw tray.

Figure 2: Low-pressure column temperature and flow profile

The following figure shows the composition profile for the low-pressure column. As expected, the top product is nearly pure nitrogen while the bottom product is nearly pure oxygen.

Figure 3: Low-pressure column composition profile

The following figure shows the feed and product stream properties for the air separation plant. You can open the Stream Table table on the Canvas to view these stream properties. As expected, the nitrogen product contains only 10 ppm (1E-5 fraction) of oxygen and the oxygen streams are each more than 99.5% pure. Due to the relative volatility of argon to oxygen, an additional catalytic deoxygenation step is required to increase the purity of the argon stream. We do not include that process is in this example.

Figure 4: Stream properties

The following figure shows the temperature profile of the E2 heat exchanger. This plate-fin heat exchanger (HXPF) models the simultaneous heat exchange between multiple hot and cold streams.

Figure 5: E2 Temperature profile

As an extension of the base case design, we analyze the impact of increasing the liquid oxygen product relative to the vapor product. The example simulation includes a scenario called Increase LiqO2 that increases the liquid oxygen product flowrate to 6 t/h. To specify the liquid oxygen product flowrate, we calculate the vapor draw to the argon column (we previously specified this value at 1875 kmol/h). The following table shows the results of this scenario. You can also find these results in the A8 - Air Separation Plant.xlsx file in the %userprofile%\MySimulations\Examples folder.

Table 2: Result of increasing the liquid oxygen product flowrate

Increasing the liquid oxygen product flowrate also increases the argon product flowrate and the purity of the argon product. This scenario also increases the purity of both oxygen products. However, it may not be possible to increase the liquid oxygen product flowrate much higher. A higher flowrate of the liquid oxygen product causes the outlet temperature of the liquid nitrogen product to increase, which in turn pushes the temperature profile in E2 close to a pinch point. This information may help inform decisions about how to approach the detailed engineering of the plant.