Excel for Chemical Engineering

 

DISTILLATION: NONREACTIVE SYSTEM USING EXCEL

This problem is intended to be an example of how Excel can be used in case of involving two units of distillation. This problem is intended to find the percentage recovery of Oxygen in the end oxygen-rich product. Percentage recovery is used when the purification of a compound is utilized. It is the ratio between the pure compound and the initial compound.

Here it is given that the air is admitted with the composition as shown in fig and admitted at 100 mol/s rates. It is required to find the oxygen recovery percentage in-stream O.

The following steps will be employed to calculate:

1.    Calculate the Degrees of Freedom to check whether the given information is enough to solve the problem and can the problem be solved. If DOF is equal to 0 then the problem can be proceeded to solve.

2.   Frame DOF for unit 1, 2 and overall indicated by the red lines.

3.   Frame the component and overall balance equations.

4.   Create a Matrices D, F using the component balance equations and determine its determinant value.

5.   If only the determinant value is approx. 0 a square matrix has an inverse.

6.   Now find the inverse which can be multiplied with matrices E and G to determine the unknowns, B, C, N, and O.

7.   Multiply the inverses with E and G to determine the unknowns.

8.   The recovery is calculated as the difference between the oxygen in N and oxygen in feed A divided by oxygen in A.


9.   It can also be calculated as the oxygen in O stream divided by the Oxygen in A.

 

 

 

 

 

 

Reference:

Stoichiometry and Process Calculations by K.V. Narayanan and B. Lakshmikutty.

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