See the screenshot below...it's probably closer to what you're looking for.

Usually, gases are measured in vol. or mol. fractions. In the sensitivity analyses, if you want to change the fraction but keep the gas flow constant you need to define on Vary the mole flow of oxygen as:

Mole-Flow Stream = Substream = MIXED Component = OXYGEN

and on Define then the mole-flow of the whole stream as

Stream-Var Stream = Substream = MIXED Variable = MOLE-FLOW Units =

and finally, on Tabulate you put /.

The mole flow of O2 is your main variable, and the first thing on the table is to show you the values as you intend them.

Frederico Gomes Fonseca , Brian Hanley Thank you for your guidance.

The reference paper sets the mass flow rate of air at 10 kg/hr.

Therefore, I input a mass flow rate of 2.1 kg/hr for O2 and 7.9 kg/hr for N2, with an O2:N2 ratio of 21%:79%.

I set the variables and defined them following your answer. However, I am uncertain if I did it correctly because the results are strange.

The values did not quite fit the theory I have studied. that if the oxygen in the air increase, hydrogen and carbon monoxide will increase as well

please attach your simulation as a .bkp file.

Brian Hanley Thank You Very much. If you don't mind, I'll attach my simulation file in a box message. :)

Hello, your problem is only mass balance when you mix air at different oxygen content with syngas? Or your problem is the effect of the oxygen on the final gas composition after the reaction?

In both case, you don't vary the concentration of the oxygen keeping the constant of the air stream because this variable is not present.

While, if this is not a problem you can vary the mole o mass flow of the oxygen (the air flow will change) and then you can write in the tabulate section the formula mole oxygen in air/ mole air (this is the inlet concentration of the oxygen that you set) and in the same way you can write mole oxygen in the gas after mixer / mole gas after mixer (that is the final concentration oxygen i.e. your result). It is obvious that you define all variable that you will write in tabulate.

If you have to keep constant the air flow, so you can try to find the variable concentration in the property set and you will se in vary section.

BR,

Domenico Flagiello

Here's a step-by-step procedure to modify the oxygen percentage in Aspen Plus:

Open your Aspen Plus simulation and navigate to the component list or component database.

Locate the air components, typically nitrogen (N2), oxygen (O2), carbon dioxide (CO2), and trace components. These components are usually available in the Aspen Plus database by default.

Adjust the Oxygen Composition:

a. Modify the mole fraction of oxygen (O2) to achieve the desired oxygen percentage. For example, if you want 30% oxygen in the enriched air, set the mole fraction of O2 to 0.3.

b. Alternatively, you can also adjust the flow rate of oxygen (O2) in the air mixture to achieve the desired oxygen percentage.

Define Specifications:

a. Define a specification or constraint to maintain the desired oxygen percentage. This ensures that the oxygen composition remains within the desired range during the simulation.

b. Specify the oxygen percentage as a variable or a target value in the specification. For example, you can set the oxygen mole fraction to be between 0.25 and 0.35 to maintain the oxygen percentage between 25% and 35% in the enriched air.

Run the Simulation:

a. Save your changes and run the simulation in Aspen Plus.

b. Aspen Plus will calculate the process behavior, considering the modified oxygen composition and the specified constraints.