# How can we draw the phase envelope inside the ternary system

• Thermo
In summary, to determine the minimum solvent and number of stages in an extraction process, you will need to draw the phase envelope (miscibility gap curve) in the ternary system triangle diagram and plot the equilibrium values of A, B, and S in both the raffinate and extract phases. The minimum solvent can be found at the intersection of the tie line and the phase envelope, and the number of stages required will depend on the desired purity and efficiency of the extraction process.

## Homework Statement

I need to determine the minimum solvent and number of stages in an extraction process. What I need to do first is drawing the phase envelope (miscibility gap curve) inside the ternary system triangle diagram. I am given the equilibrium values of A,B and S (solvent) in both raffinate and extract phases.

## The Attempt at a Solution

All examples I have the triangle is given with the curve inside in the first place. So I couldn't figure out how to draw it but I know I need it first I guess. I tried to draw it with raffinate and extract graph next to it but failed to do that.

Hi there,

To determine the minimum solvent and number of stages in an extraction process, you will first need to understand the ternary system triangle diagram and the phase envelope (miscibility gap curve) within it. The phase envelope represents the range of compositions where the three components (A, B, and S) are immiscible, meaning they cannot form a single phase.

To draw the phase envelope, you will need to plot the equilibrium values of A, B, and S in both the raffinate and extract phases. This will give you a range of points within the triangle diagram that represent the immiscible compositions. Connect these points to create the phase envelope.

Next, you will need to determine the minimum solvent required for extraction. This can be done by calculating the tie lines, which are lines connecting the equilibrium points of the raffinate and extract phases. The minimum solvent will be the point where the tie line intersects the phase envelope.

The number of stages required for extraction can be determined by plotting the equilibrium values of A, B, and S for each stage on the triangle diagram. The number of stages needed will depend on the desired purity of the extracted component and the efficiency of the extraction process.

I hope this helps guide you in determining the minimum solvent and number of stages for your extraction process. Let me know if you have any further questions. Good luck!

## 1. What is a phase envelope in a ternary system?

A phase envelope is a graphical representation of the phase behavior of a ternary system, showing the boundaries between the different phases (solid, liquid, and gas) at different temperatures and pressures.

## 2. Why is it important to draw a phase envelope in a ternary system?

Drawing a phase envelope helps us understand the behavior of a ternary system and predict the conditions at which different phases will exist. This information is crucial in industries such as chemical engineering, where the phase behavior of a system can affect the design and operation of processes.

## 3. How can we draw a phase envelope in a ternary system?

The phase envelope can be drawn by plotting the phase boundaries (i.e. the points where two phases coexist) on a graph with temperature and pressure axes. These points can be determined experimentally or calculated using thermodynamic models.

## 4. What factors can affect the shape of the phase envelope in a ternary system?

The shape of the phase envelope can be affected by factors such as the composition of the system, the temperature and pressure conditions, and the interactions between the different components. For example, a system with strong interactions between its components may have a more complex phase envelope compared to a system with weak interactions.

## 5. Can we draw a phase envelope for any ternary system?

In theory, yes. However, the accuracy and reliability of the phase envelope may vary depending on the availability and quality of experimental data or thermodynamic models for the specific system. Additionally, some systems may have very complex phase behavior that is difficult to represent graphically.