Synthesis and integration of chemical processes from a mass, energy, and entropy perspective

A method for setting performance targets for a chemical process, based on mass, energy, and entropy, is presented. These targets can be determined in the early stages of the design process to aid in the synthesis of a suitable flowsheet. These targets are "global" targets, because the overall process is considered and does not consider the individual processing units. A method of determining the minimum amount of inputs (mass, energy, and work) is illustrated by setting various targets (for example, no CO2 emissions, no energy emitted from the process, or Delta H = 0 and Delta G = 0). The approach allows one to screen the various options easily and thus determine processes that are efficient and environmentally friendly. This approach also allows opportunities of mass, heat, and work integration to be determined and applied at the earliest stages of the design process. Initially, a graphical solution is illustrated, and thereafter, the approach is generalized using a linear programming formulation. The approach is demonstrated by identifying opportunities in a methanol production plant.