Sol_HW_6_v3_KS_12oct

# Sol_HW_6_v3_KS_12oct - Chemical Engineering 150B Fall 2005...

This preview shows pages 1–3. Sign up to view the full content.

Chemical Engineering 150B- Fall 2005 Problem Set #6 Solutions Problem 1. (15 points) Consider an isothermal, isobaric ideal binary gas mixture of A and B being separated below into k streams: where n is the molar flow rate. Derive an expression for the minimum (reversible) work of separation in terms of gas constant, R, temperature T o , and mole fractions of A and B. [Hint: Try reading Seader, Chapter 1 and using Tables 2.1/2.4.] From Table 2.1 you can use the expression (4) to calculate the minimum work of separation: Since the temperature is constant, the enthalpy change is zero. Now use Table 2.4 to get the s in terms of mole fractions, where s for an ideal gas solution at constant temperature and pressure reduces to: 1 C ii i sR y l n y = =− Combining the above two equations, we arrive at the final answer: [] 1 k min o k k,A k,B o in A A B B k W R T nyl n y yl n y R T ny l n y y l n y = =+ + ⎡⎤ ⎣⎦ Through complicated mathematics, we can show that regardless of values for y between 0 and 1, W min is always positive. Since W min is independent of the process, this implies that the separation of a mixture into essentially pure species, or other mixtures of differing compositions, always require the transfer of energy to the mixture or a degradation of its energy. y A y B y 1,A y 1,B . . . y 2,A y 2,B y k,A y k,B n in n 1 n 2 n k 4 pt 8 pt 3 pt

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Problem 2. (30 Points) In petroleum refineries, a mixture of paraffins and cycloparaffins is commonly reformed in a fixed-bed catalytic reactor to produce blending stocks for gasoline and aromatic precursors for making petrochemicals. A typical multi-component product from catalytic reforming is a mixture of ethylbenzene with the three xylene isomers. If this mixture is separated, these four chemicals can be subsequently processed to make styrene, phthalic anhydride, isophthalic acid, and terephthalix acid.
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 6

Sol_HW_6_v3_KS_12oct - Chemical Engineering 150B Fall 2005...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online