Introduction to Chemical Engineering Processes/Solving problems

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Problem 1[edit | edit source]


A flash evaporator is a unit operation in which a mixture enters a chamber at a given temperature and pressure, and the vapor and liquid phases that result are separated. Suppose that a mixture of 40% furan and 60% carbon tetrachloride (which is a nearly ideal mixture [1] enters a flash evaporator at 0.7 atm and 30oC. Assuming that the mixture follows Raoult's Law, find the compositions of the liquid and vapor streams that will exit. How much of the original mixture will be vaporized?

Problem 2[edit | edit source]


Consider a process in which you want to separate the furan and carbon tetrachloride as much as possible.

a. Repeat problem 1 at pressures of 0.6 atm, 0.5 atm, and 0.4 atm. What do you notice about the purity of the two streams? What do you notice about the amount of liquid and vapor.

b. Consider a process in which half of the vapor stream is recycled (directly) to the flash evaporator. What is the effect on the composition of the liquid? On the composition of the vapor?

c. What conclusions can you draw about the effectiveness of flash evaporators?

  1. Smith, Van Ness, and Abbott. Introduction to Chemical Engineering Thermodynamics. New York: McGraw Hill, 1996, p. 433.