# How do you use the McCabe-Thiele Method?

## How do you use the McCabe-Thiele Method?

Target product quality (composition) of the top and bottom products.

1. Step 1: Establish the Plot.
2. Step 2: Add 45 Degree line.
3. Step 3: Add Equilibrium Data.
4. Step 4: Choose Product Compositions.
5. Step 5: Add the Feed Condition Line.
6. Step 6: The Rectifying Section.
7. Step 7: The Stripping Section.
8. Step 8: Stepping Down the Plot.

What is the equilibrium line in distillation?

The curved line is called the equilibrium line and describes the compositions of the liquid and vapour in equilibrium at some fixed pressure. This particular VLE plot shows a binary mixture that has a uniform vapour-liquid equilibrium that is relatively easy to separate.

### How do you draw a McCabe-Thiele graph?

The first step is to draw equal sized vertical and horizontal axes of a graph. The horizontal axis will be for the mole fraction (denoted by x) of the lower-boiling feed component in the liquid phase. The vertical axis will be for the mole fraction (denoted by y) of the lower-boiling feed component in the vapor phase.

What is the operating line in a McCabe-Thiele diagram?

McCabe-Thiele diagram The upper operating line is a graphical representation of the vapor/liquid dynamics in each stage in the rectifying section of the column (above the feed stage), while the lower operating line represents the vapor/liquid dynamics in the stripping section of the column (below the feed stage).

#### What is a Q-line?

The q-line is that drawn between the intersection of the operating lines, and where the feed composition lies on the diagonal line. Depending on the state of the feed, the feed lines will have different slopes. For example, q = 0 (saturated vapour) q = 1 (saturated liquid)

What are the main assumptions of the McCabe-Thiele method?

At the heart of the McCabe-Thiele method for a distillation column composed of equilibrium stages is the constant molar overflow (CMO) condition, which may be stated as follows: in a section of the distillation column where (i) the pressure remains the same, (ii) there are no external streams, and (iii) there are no …

## How do you find Q-line?

For a given feed condition, xF and q are fixed, therefore the q-line is a straight line with slope -q / (1-q) and intercept xF / (1-q). If x = xF , then y = xF. i.e. the q-line passes through the point (xF, xF) on the 45o diagonal.

What is the operating line?

DEFINITION. The operating line is a line representing the material balance equations. There are several options of operating line format, but one form can be obtained, by rearranging the component mass balance for y: y = -(L/V)x + (F/V)z.

### What is a good reflux ratio?

approximately 1.2 to 1.5 times R
Typically the optimum reflux ratio is approximately 1.2 to 1.5 times Rmin.