Question

A pending refinery operation is being designed. A gas stream in this operation is to be partially condensed at 80 degrees. The composition of the gas is:

A: 5% (mole)

B: 30%

C: 55%

D: 10%

Determine the pressure for the partial condenser required to condense 75% of the gas stream. Assume Raoult’s law is valid.

Use Excel to do the following:

1.Calculate the vapor pressures of the pure components.

2.Assume 100 moles of feed gas and calculate the moles of vapor and liquid that must come from the condenser.

3.Write material balances for each component around the condenser.

4.Use Raoult’s Law to relate y to x for each component in terms of its vapor pressure and the to-be-determined total pressure P.

5.Substitute the expressions you found for y into the material balances, which should each now have two unknowns --- x and P.

6.Solve for each x

7.Add the four expressions for the mole fractions x in the liquid.

8.Find P that makes the sum of the mole fractions in the liquid equal to 1.