Observation of batch distillation at different reflux ratio using McCabe-Thiele method ||@zobayerjr
Channel: Zobayer Jr
Date: 21/03/2024

Calculation:
From graph 03 
We get the value of mole fraction of distillate corresponding with absorbance at 10, 20 and 30 minutes.
When absorbance was 1.3619, then mole fraction 0.65. Similarly others data calculated on table 3 and 4 according to reflux ratio of 5:3 and 5:1.

Top operating line data calculation:
At 10 min that was first observation data on 5:3 reflux ratio, mole fraction of distillate 0.65
We know, y = L/V x+(1-L/V)x_D  
L/V=(L/D)/(1+L/D)=(5/3)/(1+5/3)=0.625
So, intercept of y is = (1-L/V)x_D = (1-0.625)×0.65=0.24375. Similarly others on table 5
For reflux ratio 5:1
L/V=(L/D)/(1+L/D)=(5/1)/(1+5/1)=5/6

Intercept of y for 10 minutes data is = (1-L/V)x_D = (1-5/6)×0.8 = 0.133333. Similarly others on table 6
Finally plotting the value and get the graphs for different reflux ratio from graph 01 and 02.

Actual stage number without reboiler in our laboratory 8
For reflux ratio 5:3
Assume fraction stage is complete one stage.
At 10 minutes data, total stage with reboiler = 3  ∴η=  2/8×100%=25%
At 20 minutes data, total stage with reboiler = 2   ∴η=  1/8×100%=12.5%

At 30 minutes data, total stage with reboiler = 1 ∴η=  0/8×100%=0%

For reflux ratio 5:1
Assume fraction stage is complete one stage.
At 10 minutes data, total stage with reboiler = 7 ∴η=  7/8×100%=87.5%
At 20 minutes data, total stage with reboiler = 3 ∴η=  2/8×100%=25%
At 30 minutes data, total stage with reboiler = 2 ∴η=  1/8×100%=12.5%
Results:
Efficiencies are in 5:3 and 5:1 that different reflux ratios at different time like 10, 20 and 30 minutes following the result:
25, 12.5 and 0% and 87.5,25 and 12.5%