A) Find the molar flow rate of the liquid product. B) Find the temperature of the recycled vapor that exits the countercurrent heat exchanger.

Question

A compound’s boiling point at P=0.5 bar is 100 K. The Linde liquefaction process is used to produce this compound in the form of saturated liquid at 100 K. The steady state process is described as follows:

• The fresh feed joins a recycle stream. The mixed stream has a flow rate of 200 mol/min.
• A series of compressors and heat exchangers converts the stream into a supercritical fluid at P=100 bar and T=160 K. At these conditions, the compound has a molar enthalpy of 3000 J/mol.
• The supercritical fluid enters a counter-current heat exchanger that decreases its temperature to 140 K, while maintaining the pressure of 100 bar.
• The 200 mol/min of supercritical fluid enters a flash chamber in which the pressure is maintained at 0.5 bar.
• The liquid product leaving the chamber is saturated liquid at 100 K and has a molar enthalpy of 0 J/mol.
• The vapor leaving the chamber has a molar enthalpy of 2500 J/mol. It is used as the coolant in the counter current heat exchanger, and is then recycled and mixed with the fresh feed.

The compound in the vapor phase behaves as an ideal gas with CP*=6R at all pressures equal to or below 1 bar, and it has CP=8R in the supercritical state at P=100 bar.

Answer 1