In several industrial processes under operation at low temperature, refrigeration system is energy intensive due to compression of refrigeration consuming high energy, resulting in high operating cost of shaft work required. To minimize the shaft work, it is accomplished by a combination of pinch and exergy analysis. Pinch analysis illustrates the simple information diagrams such as composite curves and grand composite curve as tools for process modifications. However, the weakness of pinch analysis is that it cannot deal with power or shaft work. Exergy analysis is a tool to utilize power or shaft work and identifies thermodynamic imperfection of process such a magnitude of exergy loss in each unit. Both strengths are combined to help improve process efficiently. This methodology is applied to case study of LNG simulated by commercial software ProII and a graphical exergy-pinch analysis is applied to help improve processes such as reducing shaft work and increasing the exergy target.
