Technology Alerts: HYDROGEN

Type	Journal Article
Author	Xiaoqiang Liang
Author	Lixia Kang
URL	http://dx.doi.org/10.1021/acs.iecr.5b04120
Volume	55
Issue	9
Pages	2574-2583
Publication	Industrial & Engineering Chemistry Research
Date	March 9, 2016
Abstract	The operating conditions of hydrogen networks in refineries fluctuate due to variation of feed properties, loss of catalyst activity, change of market demand, seasonal shift, and improvements in processing technology. Such fluctuations can affect the hydrogen network operation. Typically, these networks are optimized on the basis of fixed operational conditions. Authors present a flexible design method of a multiperiod hydrogen network. It features the flexible design of multiperiod hydrogen network by considering discrete operational scenarios in multiple periods and possible fluctuation of each operational scenario. The optimal design of the multiperiod hydrogen network with simple structure and low total annual costs can be obtained using their method. Furthermore, the bottlenecks restricting the flexibility of each subperiod can be identified and eliminated. In addition, the method can be readily implemented. A multiperiod hydrogen system in a refinery is used to exemplify the proposed method. Results demonstrate that the method can be used to effectively obtain the hydrogen network structure that satisfies the multiperiod operational conditions and reach the flexibility requirements for each subperiod with the lowest total annual costs.

Type	Journal Article
Author	Brian D. Ehrhart
Author	Christopher L. Muhich
URL	http://www.sciencedirect.com/science/article/pii/S0360319915303554
Publication	International Journal of Hydrogen Energy
Date	2016
Abstract	Authors calculated the solar-to-hydrogen (STH) efficiency for a variety of operating conditions for a two-step metal oxide solar thermochemical hydrogen production cycle using cerium(IV) oxide. They considered an inert sweep gas as the O2 removal method. Gas and solid heat recuperation effectiveness values were varied between 0 and 100% in order to determine the limits of the effect of these parameters. The temperature at which the inert gas is separated from oxygen for an open-loop and recycled system was varied. The hydrogen and water separation temperature was varied as well, and the effect on STH efficiency quantified. Their study demonstrates that gas heat recuperation is critical for high efficiency cycles, especially at conditions that require high steam and inert gas flowrates. They identify a key area for future study to be the development of ceramic heat exchangers for high temperature gas–gas heat exchange.

Type	Journal Article
Author	Qiao Zhang
Author	Huachao Song
URL	http://dx.doi.org/10.1021/acs.iecr.6b02098
Volume	55
Issue	39
Pages	10344-10354
Publication	Industrial & Engineering Chemistry Research
Date	October 5, 2016
Abstract	Hydrogen network integration is an effective way to conserve fresh hydrogen in a refinery environment. On the basis of relative concentration analysis, researchers designed a mixed integer linear programming (MILP) mathematical model to synthesize refinery multi-impurity hydrogen networks. The model, by correlating the hydrogen consumption of a sink with its oil processing throughputs, reveals the fresh hydrogen variation tendency caused by fluctuation of each capacity, and determines the key sink(s) of a hydrogen network with multiple impurities on the premise of minimum fresh hydrogen consumption. With a structure matrix variable, the model can analyze practical hydrogen networks. Results demonstrate that the method is superior to conventional absolute concentration-based methods in fresh hydrogen conservation under cases of static, fluctuant throughputs, and fluctuant throughputs with restricted network structure. Two cases are presented to demonstrate its application.

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