In order to produce
liquefied methane we use the simple
liquefaction process and then the Linde
process.The conditions of the gas
at a different location are such that methane is initially available at 1 bar and 300 K and methane leaving the cooler will be at 100 bar and 200 K. The flash drum is
adiabatic and operates at 1 bar,
and each compressor stage can be assumed to operate reversiblyand adiabatically.
A three-stage compressor will be
used, with the first stage compressing
the gas from 1 bar to 5 bar, the second stage from 5 bar
to 25 bar, and the third stage from 25 bar to 100 bar.
Between stages the gas will be isobarically
cooled to 200 K.

a. Calculate the amount of work required for each kilogram of methane that passes through
the compressor in the simple liquefaction process.

b. Calculate the fractions of vapour and
liquid leaving the flash drum (Fig 5.1-1) of the. simple liquefaction process and the total amount of compressor work
required for each kilogram of LNG produced.

c. .Assuming that the
recycled methane leaving the heat exchanger in the Linde process (Fig. 5.1-2) is at 1 bar and 200 K, calculate
the amount of compressor work required per kilogram of LSG produced.