Page 256 - Chemical Process Equipment - Selection and Design

8.13. REFRIGERATION 225

Critical point Saturated liquid line
\
Saturated vapor line
arge
heat
m
.-
a
u)
5
2
fn
E
a
Enthalpy, h (Btu/lb)
(b)

stage stage
Brine pump (d)
(c)
figure 8.24. Simpler circuits of compression refrigeration (see also Example 8.17). (a) Basic circuit consisting of a
compressor, condenser, expansion valve and evaporator (load). (b) Conditions of the basic circuit as they appear on a
pl-essure-enthalpy diagram; the primed points are on the vapor-liquid boundary curve. (c) Circuit with circulation of
refrigerated brine to process loads. (d) Circuit with two-stage compression and intercooling.

EXAMPLE 8.117 recycled to the suction of the high pressure stage while the liquid is
Two-Stage Propylene Compression Refrigeration with Inter- expanded to 16 psia to provide the needed refrigeration at -9°F.
stage Recyele The ratios of refrigeration to power input will be compared without
A propylene refrigeration cycle operates with pressures of 256, and with interstage recycle.
64, and 16psia. Upon expansion to 64psia, the flashed vapor is Basis: 1 Ib of propylene to the high pressure stage. Conditions

High pressure
stage

I ' Low pressure Enthalpy
Load stage