A classic cascade LNG design includes cooling the inlet gas with water, propane, ethane, and methane refrigerants before a final cooling process through a J-T expansion. The gas is converted to LNG has been processed for NGL removal and essentially consists of methane. Gas enters the liquefaction section at 104^oF and 1000 psia at a rate of 400 MMscfd. Cooling water is supplied at 80^oF. All heat exchangers have a pressure drop of 10 psi and an approach temperature of 10^oF. The suction pressure for the refrigeration compressors is at atmospheric pressure. The final LNG flash is at 10 psig and the remaining vapors are sent to a fuel compressor.

a. Draw a diagram of the inlet gas flow through the liquefaction system showing the gas temperatures leaving each refrigerant step.

b. What is the duty of each of the gas cooling steps?

c. What is the fraction of the inlet gas being sent to storage as LNG?