Analysis of the Relation between Coupled Sink and Purification Based on Hydrogen Network Integration

In a hydrogen network, sinks and sources are generally connected to reactors or purifiers, which affect their compositions and flow rates. The relationship between these streams is studied based on the integration of the hydrogen network to identify the feasible and optimal operating conditions of reactors and purifiers. Equations are deduced to describe the quantitative relationship between hydrogen consumption, hydrogen concentration, flow rates of coupled sink and source, purification feed, and purified product. The purification and hydrogen‐consuming reactor parameters can be optimized in the design and operation stage of a hydrogen network. The case study proves that the proposed method is simple, easy to understand, and can be applied to identify the variation trend line and feasible region accurately without tedious calculation.     

储氢提纯和氢网络的耦合优化

基于氢网络的集成以及AB₅型储氢材料LaNi_4.75Fe_0.25及LaNi_4.85Al_0.15的特性,对储氢提纯在氢网络中的应用进行研究。综合考虑LaNi_4.75Fe_0.25及LaNi_4.85Al_0.15储氢/放氢动力学,建立了储氢提纯氢网络的优化方法,根据单位质量储氢材料提纯的节氢能力和公用工程节省量与提纯参数的关系,确定最优提纯氢源浓度、最大公用工程节省量、储氢材料量和吸氢时间。用该方法对某炼厂氢网络和储氢提纯单元进行优化,结果表明,最优提纯氢源浓度为70%,提纯后公用工程可节省23.72%; LaNi_4.85Al_0.15作为储氢提纯材料优于LaNi_4.75Fe_0.25,其消耗量为991.26kg。     

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.     

简捷法确定提纯回用氢网络目标值

与只考虑直接回用的氢网络相比,具有提纯单元的氢网络能显著减少新鲜氢气的消耗量,但其设计及求解提纯目标值过程均更为复杂。对于单杂质、提纯单元采用固定浓度模型的提纯回用氢网络,结合此类网络的特点,提出了一种简捷法确定网络目标值。首先假设提纯后氢物流量足够大,由此得出初始提纯夹点。当初始夹点估算正确时,由夹点之下的需求物流和源物流的流量与杂质质量衡算即可得出提纯回用氢网络的目标值;当初始夹点估算不正确时,可以第一次计算结果为基础判断得出正确夹点,再增加一步简单计算,也可得到提纯回用目标值。计算实例表明本文方法计算简单且有效。     

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.     

提纯回用氢网络的夹点变化规律

在氢系统中引入提纯装置可以经济有效地提高氢气的回用率,是氢系统中广泛采用的方法。但引入提纯回用过程可能会影响氢系统的夹点位置,还可能使氢系统出现多夹点。由于夹点对系统性能的分析与优化具有极其重要的作用,而夹点位置的变化则会影响到用氢过程的匹配。在氢夹点技术的基础上,通过图示分析法,研究了在不同提纯产品浓度下提纯回用过程的夹点变化规律和趋势,对于考虑提纯回用的氢网络集成具有重要的意义。     

应用于空分纯化系统的相变储热器建模及分析

为实现空分纯化系统污氮气余热的回收再利用,设计了一种采用相变储热器的新型空分纯化系统,同时提出了相应的相变储热器设计方法。首先,对空分纯化系统进行数据采集,并通过回归获得污氮气温度、流量等参数的特性函数。随后,建立了非稳态变温热源下的相变储热器动态数学模型,并推导相变材料在污氮气特性函数作用下的温度通用表达式。其次,以储、放热整体循环的最大放热量为目标函数,采用微分进化算法优化储热器内相变材料熔化温度、质量等关键参数。最后,通过穷举计算了单、双级相变储热器中相变温度与余热利用率之间的关系。计算结果表明,对于单级相变储热器,最佳的相变温度为59.67℃,最大余热利用率约为0.41;对于双级相变储热器,第一级和第二级的最佳相变温度分别为73.68℃和46.04℃,最大余热利用率约为0.52。本研究为提升空分纯化系统能效奠定了理论基础。     

石化园区厂际提纯回用氢气系统优化

石化园区化肥厂、乙烯厂等富氢气体送往炼油厂,能够缓解炼油厂的氢气亏缺,因而石化园区厂际氢气系统优化具有重要的意义.本文构建了石化园区厂际提纯回用氢气系统超结构模型,以年度化总费用为目标函数,建立优化的数学模型,使用商业优化软件GAMS平台建模,用DICOPT作为求解器.对某石化园区的氢气系统进行了优化,结果表明,总的年度化费用比现行的系统降低了33.1%.     

RESEARCH NOTES Unified model of purification units in hydrogen networks

Purification processes are widely used in hydrogen networks of refineries to increase hydrogen reuse. In refineries, hydrogen purification techniques include hydrocarbon, hydrogen sulfide and CO removal units. In addition, light hydrocarbon recovery from the hydrogen source streams can also result in hydrogen purification. In order to simplify the superstructure and mathematical model of hydrogen network integration, the models of different purification processes are unified in this paper, including mass balance and the expressions for hydrogen recovery and impurity removal ratios, which are given for all the purification units in refineries. Based on the proposed unified model, a superstructure of hydrogen networks with purification processes is constructed.     

具有净化单元氢网络的迭代设计方法

提出一种具有净化单元氢网络的迭代设计方法。首先假设净化后源物流的量足够大,将之看作系统的新增源物流即可构成具有净化单元的初始氢网络。运用多氢源匹配方法来设计氢网络,从而得到净化后源物流的用量F_reg和所有未回用的内部源物流合并计算出的净化后源物流的量F_reg^total。比较F_reg和F_reg^total的大小,当F_reg^totalreg时,将F_reg^total作为下一次迭代净化后源物流的量的初值,只需几次迭代即可得到最终设计;当F_reg^total≥F_reg时,将F_reg的值作为最终设计的净化后源物流的用量,按照由F_reg值确定出的净化前源物流的量选取杂质浓度较低的未回用的内部源物流用于净化,对此种情况,不需后续迭代即可得到最终设计。对文献中几个实例的研究表明,该方法设计步骤简单可行,不仅能得到氢消耗目标值,而且还能得到氢网络的具体设计。     

Optimization models for shale gas water management

There are four key aspects for water use in hydraulic fracturing, including source water acquisition, wastewater production, reuse and recycle, and subsequent transportation, storage, and disposal. Water use life cycle is optimized for wellpads through a discrete‐time two‐stage stochastic mixed‐integer linear programming model under uncertain availability of water. The objective is to minimize expected transportation, treatment, storage, and disposal cost while accounting for the revenue from gas production. Assuming freshwater sources, river withdrawal data, location of wellpads, and treatment facilities are given, the goal is to determine an optimal fracturing schedule in coordination with water transportation, and its treatment and reuse. The proposed models consider a long‐time horizon and multiple scenarios from historical data. Two examples representative of the Marcellus Shale play are presented to illustrate the effectiveness of the formulation, and to identify optimization opportunities that can improve both the environmental impact and economical use of water. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3490–3501, 2014     

Surplus diagram and cascade analysis technique for targeting property-based material reuse network

Recycle of process and waste streams are among the most effective resource conservation and waste reduction strategies. In many cases, recycle/reuse is dictated by sink constraints on properties of the recycled streams. In this work, we introduce an algebraic technique to establish rigorous targets on the minimum usage of fresh resources, maximum direct reuse, and minimum waste discharge for property-based material reuse network. Two new tools have been developed. A new graphical tool called the property surplus diagram is firstly introduced to provide a basic framework for determining rigorous targets for minimum fresh usage, maximum recycle, and minimum waste discharge. The tools also determine the property-based material recycle pinch location. The Property Cascade Analysis (PCA) technique is next established to set targets via a tabular approach. PCA eliminates the iterative steps typically associated with a graphical approach. Along with the minimum fresh and waste targets, the material allocation target is another key feature of the PCA. A network design technique is also presented in this paper to synthesise a maximum resource recovery (MRR) network that achieves the various established targets. The procedures developed in this paper constitute a generalisation to the composition-based graphical and algebraic techniques developed for water and hydrogen recovery networks. Two case studies are solved to illustrate the applicability of the developed procedures.     

Addressing water scarcity: cationic polyelectrolytes in water treatment and purification

Synthetic cationic polyelectrolytes (CPEs) serve as coagulation and flocculation agents in wastewater treatment due to a synergy of inherent electrostatic interactions and hydrophilic properties. In wastewater treatment, CPEs act as coagulation and flocculation agents to aggregate impurities and enable water purification. New health and environmental‐related regulations provide motivation for government agencies and industrial companies to reuse wastewater. Chemical structure, molecular weight, charge density and functionality of CPEs provide tailorability for specific purification needs. Cationic polyacrylamides, ammonium‐based polymers, poly(allyldimethyl‐ammonium chloride) and epichlorohydrin/dimethylamine‐based polymers are the most common CPEs used as coagulation and flocculation agents because they are economical and water soluble with tunable charge densities at high molecular weights. Free radical polymerization, step‐growth polymerization and post‐polymerization modification methods afford each polymer system. This review highlights recent advancements in synthetic methods to yield CPEs, structure?property relationships as related to flocculation efficiency and a summary of their toxicity and environmental impact. © 2018 Society of Chemical Industry     

过氧化氢提纯净化技术研究进展

简要介绍了过氧化氢的应用及生产工艺。重点介绍了包括蒸馏法、吸附法、离子交换树脂法、膜分离法、结晶法、超临界流体萃取法等几种过氧化氢提纯净化技术的优劣。指出在中国电子工业飞速发展的大背景下,高纯过氧化氢的需求进一步扩大;过氧化氢的提纯净化技术要求向大型化、规模化的方向发展;近些年开发出的以离子交换树脂为核心的多单元集成纯化方法,通过对纯化技术的整合,既保证了高品质的质量要求,又兼顾了经济性、安全环保性。     

基于层次分析法优化天然气净化工艺

为了避免杂质腐蚀设备或因低温冻结而堵塞换热器,天然气在进入液化装置前需对其进行净化处理,即脱除天然气中的酸性气体(CO₂、H₂S)和水分。本文选用二乙醇胺(DEA)法脱除天然气中的酸性气体,用三甘醇(TEG)法脱除天然气中的水分,通过耦合DEA法和TEG法得到最终天然气净化工艺,且达到净化指标要求。但由于工程手册只能给出工艺参数的大概范围,尚无法得到最优的工艺方案,因此本文首先应用化工模拟软件HYSYS8.4对天然气工艺过程进行模拟计算,然后在工艺参数推荐范围内设定9组推荐方案,引入系统评价方法中的层次分析法,并基于Matlab程序计算,对9组推荐方案进行多目标综合评价,最终确定最优的净化组合方案。本文可为天然气净化工艺和其他工艺方案的优选提供指导。     

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.     

溶剂沉淀法净化萃余酸工艺研究

为了能循环利用湿法磷酸净化的萃余酸，实验研究了溶剂沉淀法净化萃余酸的工艺条件，选择以乙醇和异丙醇体积比为1的混合醇作为溶剂，对不同杂质含量的萃余酸进行了净化除杂。实验结果表明：在溶剂与萃余酸体积比为5：1、反应时间为30min、反应温度为75℃的条件下对萃余酸中的金属离子的去除率达75％以上，达到净化萃余酸循环利用的要求，蒸馏回收溶剂也可循环利用。     

过氧化氢中无机杂质净化技术进展

综述了过氧化氢中无机杂质的来源和高纯过氧化氢生产中无机杂质的净化技术研究进展,这些技术包括：精馏法、离子交换树脂法、吸附法、结晶法、絮凝法、膜分离技术,以及这些技术的组合净化技术等.精馏净化产品纯度不高,但技术成熟,可工业放大;膜分离净化技术较安全,但膜的寿命短;离子交换树脂工艺简单,净化效率高,但树脂易被氧化.指出以精馏为前净化技术,再与膜分离、树脂法相结合是无机杂质去除技术的发展趋势.     

A stepwise optimal design of water network☆

In order to take full advantage of regeneration process to reduce fresh water consumption and avoid the accumu-lation of trace contaminants, regeneration reuse and regeneration recycle should be distinctive. A stepwise opti-mal design for water network is developed to simplify solution procedures for the formulated MINLP problem. In this paper, a feasible water reuse network framework is generated. Some heuristic rules from water reuse net-work are used to guide the placement of regeneration process. Then the outlet stream of regeneration process is considered as new water source. Regeneration reuse network structure is obtained through an iterative optimal procedure by taking the insights from reuse water network structure. Furthermore, regeneration recycle is only utilized to eliminate fresh water usage for processes in which regeneration reuse is impossible. Compared with the results obtained by relevant researches for the same example, the present method not only provides an appro-priate regeneration reuse water network with minimum fresh water and regenerated water flow rate but also sug-gests a water network involving regeneration recycle with minimum recycle water flow rate. The design can utilize reuse, regeneration reuse and regeneration recycle step by step with minor water network structure change to achieve better flexibility. It can satisfy different demands for new plants and modernization of existing plants. ? 2016 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. Al rights reserved.     

高纯过氧化氢生产中有机物杂质的净化技术进展

介绍了工业级过氧化氢中有机物杂质的来源,综述了高纯过氧化氢生产中有机物杂质的净化技术研究进展,包括精馏、吸附、离子交换树脂、溶剂萃取、结晶、膜分离技术以及这些技术的组合净化技术。精馏净化产品纯度不高,但技术成熟,可工业放大;膜分离净化技术较安全,但膜的寿命短;吸附树脂工艺简单、净化效率高,但树脂易被氧化。指出以精馏为前净化技术,再与膜分离、树脂吸附相结合是有机碳杂质去除技术的发展趋势。