This paper presents a simple graphical method for determining the minimum hydrogen demand. In the pure hydrogen load versus flow rate diagram, the sink and source composite curves are constructed, and they can shift freely in every direction. Through moving the hydrogen source composite curve to the position at which the two composite curves intersect at only two points, the hydrogen pinch point of the system is identified. Furthermore, the minimum utility consumption can be determined from the diagram. This method is simple, efficient, and easy to understand. It can be used in hydrogen systems with any utility concentration.
in Wiley Online Library (wileyonlinelibrary.com).The purification reuse/recycle is one effective resource conservation strategy. In this article, a novel conceptual method is proposed to identify the optimal purification feed flow rate (PFFR) and the corresponding maximum hydrogen utility savings (HUS) of the hydrogen network with purification reuse/recycle. In this method, the sources and sink-tie-lines are divided into three regions according to the purified product and purification feed. The quantitative relationship between the HUS and the PFFR is analyzed for the sink-tie-lines and sources of each region. With the quantitative relationship line between the HUS and the PFFR of each source plotted, the quantitative relationship diagram can be obtained and can be used to identify the pinch point and the HUS for a given PFFR. Furthermore, the optimal PFFR and the maximum HUS can be identified easily. Three cases are studied to illustrate the applicability of the proposed method.
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