Mass-Exchange Network Synthesis Task

The candidate lean streams can be classified into Nsp process MSAs and Nse external MSAs (where Nsp + Nse — Ns). The process MSAs already exist on plant site and can be used for the removal of the undesirable species at a very low cost (virtually free). The flowrate of each process MSA that can be used for mass exchange is bounded by its availability in the plant, i.e., 

CHAPTER THREE Synthesis of mass-exchange networks 

Typically, waste streams are either disposed of or forwarded to process sinks (equipment) for lecycle/reuse. In case of hnal discharge, the taiget composition of the undesirable species in each waste stream corresponds to the environmental regulations. On the other hand, if the intercepted waste stream is to be recycled to a process sink, its target composition should satisfy the constraints imposed by the process sink. 

The target composition of the undesirable species in each MSA is assigned by the designer based on the specific circumstances of the application. The nature of such circumstances may be physical (e.g., maximum solubility of the pollutant in the MSA), technical (e.g., to avoid excessive corrosion, viscosity or fouling), environmental (e.g., to comply with environmental regulations), safety (e.g., to stay away from flammability limits), or economic (e.g., to optimize the cost of subsequent regeneration of the MSA). 

As can be inferred from the problem statement, for a given waste-reduction situation the MEN synthesis task attempts to provide cost-effective solutions to the following design questions  

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