Synthesis of mass integration networks: Integrated approach to optimization of stream matching for a metal pickling process

The purpose of this techno-economic feasibility study is to develop a procedure for the cost-effective synthesis and optimization of schemes to recover in-plant a valuable ingredient from waste streams and at the same time reduce the COD property. MILP and MINLP algorithms are used. The model minimizes the total annualized cost of the mass exchange network (MEN). The procedure involves a two-stage process: first, using the MILP, the pinch point location is identified along with the selection of an optimal set of mass separating agents (MSAs). At this stage the effect of each selected MSA on COD is scrutinized. In the second stage, the MINLP is applied to realize the optimal matching of waste and lean streams through the direct minimization of equipment capital cost. An example is presented to show the applicability and advantages of the proposed novel procedure. The project was found to be highly profitable.

► Stream matching through direct fixed cost optimization rather than number of exchangers.
► Depreciation cost was linearized through simple linear regression.
► Simultaneous mass and property constraints modeling using MILP and MINLP.