Solve problem 5.11 using an economizer at the intermediate pressure and referring to Fig. 5.10 for stream numbers.

Data from problem 5.11:

The low-temperature condenser of a distillation column is to be operated using a propane refrigeration unit. The evaporator is to operate at -20°C. The cooling duty is to be 10,000,000 kJ/ hr. The compressor is to be a two-stage compressor with an adiabatic efficiency of 80% (each stage). The compression ratio (P^out/Pⁱⁿ) for each stage is to be the same. The condenser outlet is to be at 50°C. Refer to Fig. 5.8 for stream numbers.

(a) Find the condenser, evaporator, and compressor interstage pressures.

(b) Find the refrigerant flowrate through each compressor.

(c) Find the work input required for each compressor.

(d) Find the cooling rate needed in the condenser.

Transcribed Image Text:

Flash Chamber 8 6 Hot Side Condenser Throttle Valve 7 1 Throttle Valve Vapor Phase Only Evaporator Cold Side 2nd Stage Compressor 5 1st Stage Compressor Figure 5.10 Flash chamber intercooling. 2 T P Liquid 8, 6 /4 const. P H 4 7 Two-Phase Region S 3 5