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Hydrogen management is important in refineries in achieving cost competitiveness to produce clean and lowsulfur fuels. Other than minimizing the fresh hydrogen requirement, it is extremely important to reduce the compression work, required in any hydrogen allocation network (HAN). In this paper, a rigorous targeting methodology to minimize compression work in a HAN is proposed. The proposed methodology is algebraic and addresses flow, concentration, and pressure constraints in HAN. On the basis of the rigorous mathematical arguments, it has been proved that problem of minimizing compression work requirement in a HAN with multiple pressure levels can be broken into various subproblems having two pressure levels only and the compression work requirement for two pressure levels can be minimized via minimizing cross-flows between these pressure levels. The applicability of the proposed algorithm is demonstrated through illustrative examples.

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Utilization of multiple freshwater resources can significantly reduce the operating cost of a water allocation network. This is demonstrated in the literature for continuous processes. In this paper, a mathematical formulation is proposed to minimize the operating cost of water allocation network in a batch process by utilizing multiple freshwater resources. The proposed methodology incorporates the variable scheduling of a batch process, for a given production, and it is applicable to single as well as multicontaminant water allocation problems. The applicability of the methodology is demonstrated with two illustrative examples. In these two examples, in comparison to single freshwater use, reductions of 17% and 32% in operating costs are observed.

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