Purification Reuse Research Articles

A unified graphical method for integration of hydrogen networks with purification reuse

Introducing purifiers into hydrogen network can enhance the recovery and reuse of hydrogen in refineries, further reducing the consumption of fresh hydrogen. Based on previous graphical methods, this work proposes a simple and unified graphical method for integration of hydrogen networks with purification processes. Scenarios with different hydrogen concentrations of purified product can be analyzed by the unified procedure. As a result, the maximum hydrogen saved by purification reuse can be identified and the corresponding purification process can be optimized. The proposed method is easy and non-iterative, and it is valid to purification processes with any feed concentration. A conventional hydrogen network is analyzed to test the effectiveness of the proposed method.

Relative concentration based pinch analysis for targeting and design of hydrogen and water networks with single contaminant

Hydrogen and water are important resources for refineries. Pinch based conceptual method is an effective tool for fresh resource conservation of hydrogen and water networks. A novel graphical method is proposed to identify the minimum consumption of fresh resource and design the network for both hydrogen and water networks with single contaminant. This method replaces traditional total flow rate and absolute concentration constraints with hydrogen load and relative concentration, constructing the composite curves in contaminant load versus hydrogen load diagram to perform the targeting and design process. Furthermore, the proposed method can be reinforced by integrating purification reuse, conserving more fresh hydrogen and further reducing the waste discharge. This new method is visible, simple and easy to understand, suitable to both hydrogen and water networks. Three cases are studied to illustrate its application.

Effect of Purification Feed and Product Purities on the Hydrogen Network Integration

For a hydrogen network with purification, different purification feed purities (PFPs) and purified product purities (PPPs) will exert different effects on utility consumption. To optimize a hydrogen network with purification reuse, the effect of PFP and PPP on the hydrogen utility consumption should be analyzed systematically. According to the quantitative relationship of the hydrogen surplus at each sink-tie-line, the limiting PFP and PPP can be identified from the hydrogen surplus variation diagram. For sink-tie-lines at different regions, the quantitative relationships between the HUS and the PFP/PPP are analyzed. With the quantitative relationship line between the HUS and the PFP/PPP of each sink-tie-line plotted, the quantitative relationship diagram can be obtained. Based on this, the pinch point and the HUS for a given PFP/PPP can be identified. Furthermore, the limiting PFP and PPP, the optimal PFP and PPP, and the maximum HUS can also be targeted easily. A case is studied to illustrate the applicability of the proposed method.

Graphical Method for Integrating Purification Processes in Hydrogen Systems with Constraints of Flow Rate and Concentration

Introducing purification devices into hydrogen systems can enhance the extent of hydrogen reuse. The economic performance of a purification device depends on its appropriate placement within a hydrogen system. This work presents an improved version of a previously published graphical method for integrating purification processes in hydrogen systems. A mathematical method is deduced for calculating the maximum hydrogen utility savings potential of a hydrogen system with purification reuse. The improved graphical method is able to handle the constraints of concentration and flow rate of a purification process when targeting the maximum hydrogen utility savings. The proposed method can be used for analyzing purification processes with any feed concentration. The graphical method is tested on two case studies.

Pinch Location of the Hydrogen Network with Purification Reuse

In the hydrogen network with the minimum hydrogen utility flow rate, the pinch appears at the point with zero hydrogen surplus, while the hydrogen surpluses of all the other points are positive. In the hydrogen purity profiles, the pinch can only lie at the sink-tie-line intersecting the source purity profile. According to the alternative distribution of the negative and positive regions, the effect of the purification to the hydrogen surplus is analyzed. The results show that when the purification is applied, the pinch point will appear neither above the purification feed nor between the initial pinch point and the purification feed, no matter the purification feed lies above or below the initial pinch point. This is validated by two case studies.

A conceptual method for targeting the maximum purification feed flow rate of hydrogen network

For a hydrogen network with purification, it is postulated that different Purification Feed Flow Rates (PFFRs) will exert different effects on the hydrogen utility consumption. To optimize a hydrogen network with purification reuse, the effect of the PFFR on the hydrogen utility consumption should thus be analyzed systematically. However, no in-depth studies on this subject matter are available in the open literature. This work aims to bridge this research gap by establishing the relationship between the PFFR and the hydrogen utility consumption. According to the concepts of hydrogen surplus and pinch point, the characteristic of the pinch point is analyzed first, and it is found that the pinch point can only appear at the sink-tie-line which can intersect the source purity profile. Then, the quantitative relationship between the hydrogen utility adjustment and the hydrogen surplus is deduced, and a numerical method for identifying the pinch point and the minimum hydrogen utility consumption target is developed. Based on this, the quantitative relationship between the PFFR and the hydrogen surplus at each sink-tie-line is deduced. The upper bound of the PFFR can be identified from the hydrogen surplus variation diagram. The proposed numerical approach for targeting the hydrogen pinch problems and a systematic graphic method for identifying the limiting PFFR have the merit of being conceptually simple and easy to apply. Two cases are studied to illustrate the applicability of the proposed method.

A novel graphical method for the integration of hydrogen distribution systems with purification reuse

Increase in refining demand and tighter environmental regulations have led to sharp increases in hydrogen consumption of oil refineries. Hydrogen conservation and effective use are of interest to refineries whose operations and profitability are constrained by hydrogen. Purification is widely used in hydrogen networks of refineries to reduce hydrogen production load. To minimize hydrogen utility consumption, it is necessary to optimize the hydrogen network with purification as a whole. In this paper, for hydrogen purification process, a triangle rule (which can be generalized to polygon rule) is proposed for graphical representation of its mass balance. The proposed procedure treats the product concentration and recovery rate of the purification process as adjustable parameters. An ensuing graphical method is developed for targeting the pinch point and minimum utility consumption of the hydrogen system with purification reuse. This graphical method can be used for any purification devices and in systems with any utility concentration. A refinery case is studied to demonstrate the optimization method.