水系统集成方法分析

水系统集成技术把企业的整个用水系统作为一个有机的整体来考虑水在系统中的优化分配,能够取得显著的节水效果。本文分析了近年来发展的过程水系统集成方法,主要包括水夹点技术、数学规划法和中间水道技术,指出了这3种水网络优化技术的特点及优缺点,并通过一个例子对这3种方法进行了比较。最后对水系统集成方法的发展作出展望。     

水系统集成优化方案的博弈分析与评价方法

对水系统集成优化方案的分析和决策需要考虑新鲜水用量、用水系统的柔性和用水网络结构的复杂程度等方面。水网络优化设计方案的确定一般需要在这三者之间进行折中和协调,属于多目标优化问题。为了综合考虑新鲜水消耗量和网络结构复杂程度等指标,并定量分析和确定水网络的优化设计方案,本文提出一种基于博弈分析的水网络优化方案的定量分析方法。以具有中间水道水网络优化设计方案的决策为例,采用本文方法进行了优化设计方案的分析与评价。研究表明：该定量分析和评价用水网络的方法可以合理地评价用水网络的设计方案,该方法可用于定量确定水系统优化问题中的多目标优化方案,可为水系统优化集成方案的确定提供分析依据和指导。     

水系统集成技术在火力发电厂的应用

火力发电厂是工业耗水和排水大户,节水潜力较大。利用水系统集成技术对某电厂的现有水网络进行优化改造,优化后水网络节水效果明显,且实现了电厂污水的近零排放。提出了水网络优化的基本路线和科学方法,为火力发电厂用水网络优化设计和改造提供理论依据。     

通过改进网络结构提高多杂质水系统柔性的集成方法

水系统集成导致用水过程之间联系紧密、相互作用、相互影响.为了改善系统柔性,可通过改进网络结构提高系统的柔性.对多杂质水回用网络系统的柔性进行了分析,提出了用过程附加控制数和过程连接数同时表征多杂质水回用系统柔性的评价指标,建立了新鲜水耗量最小化、过程附加控制数优化和过程连接数优化的分步优化数学模型,并通过多杂质水网络实例研究了该方法的可行性,得到了具有最小新鲜水耗量、过程附加控制数和过程连接数均最小的水网络结构.     

水系统集成技术在甲醇厂的应用

水系统集成技术是把整个工业用水系统作为一个整体来看待,并考虑水质、水量的分配,从而使系统用水的重复利用率达到最大,同时废水排放量最小。甲醇企业是用水和废水排放的大户,将水系统集成技术应用于甲醇工业,具有重要意义。文中结合水系统集成技术的工业应用现状,总结了水系统集成技术在工业企业中应用的一般步骤,具体分为以下几步:选定目标系统,明确水源水阱,确定关键污染物组分和极限进出口浓度,生成初始网络和用水网络调优。并以某甲醇厂简化的用水系统为实例,采用文中所提出的一般应用步骤,对用水网络进行了优化,获得了新鲜水节水率达34.5%的节水效果。     

过程水系统集成技术及其进展

水系统集成技术是将整个企业的用水系统作为一个有机的整体来对待的一种技术,可以有效地节省新鲜水用量,并同时减少污水的排放.介绍了近年来在过程水系统集成方面的研究进展.对于常规水网络结构,主要包括两方面的研究水夹点技术与数学规划法,指出了两种技术的优势与缺陷及有待进一步研究的问题.还介绍了一种新的水网络--基于中水道的水网络--的研究与进展.     

具有最简结构水回用网络的优化

当前对水回用网络的研究主要集中在如何构造新鲜水量最小的水网络, 却忽视了该水网络的不唯一性.为了降低水回用网络的费用,应考虑水网络的最简结构.今用连接数的概念来描述用水网络的结构复杂性.连接数就是新鲜水道与过程、过程与过程、过程与废水道之间连接个数的总和.今以最小新鲜水量和网络连接数为目标,在网络超结构的基础上,建立了多杂质水回用网络优化的数学模型.用该模型确定的用水网络,具有最小新鲜水用量和最简结构,因而具有很好的经济性.最后通过实例说明了本方法的有效性.     

煤化工园区单杂质水网络系统集成的探讨

如何在保证产业发展的条件下,有效的利用水资源是煤化工产业目前面临的重要问题,水系统集成技术是合理利用水资源的有效方法之一。本文以内蒙古一个典型的煤化工工业园为研究对象,对园区内所属企业用水单元的情况进行了数据调研和分析,得到该园区的部分用水单元存在节水的潜力的结论。通过选取园区企业内的部分净水系统用水单元,以COD作为关键杂质组分的研究对象,利用系统过程集成技术中的水夹点理论进行了计算调优,并重新设计水网络,最终达到节水的目标。     

再生循环水网络设计在火电厂的应用

为解决水网络集成优化方法在火电厂水网络优化应用中存在的问题，该研究对杂质的传递过程进行了扩展，使用移质推动描述杂质负荷单元用水过程，以及用最大移质能力及移除率描述再生过程，并通过邻接矩阵描述网络单元间的连接关系，从而构建再生循环水网络模型；对3300 MW火电厂进行模型应用研究，将案例水网络划分为9个用水子系统，等效拆分为11个用水单元并对移质单元构建浓度修正模型从而实现最大移质过程，选取Cl^-、总悬浮固体(SS)、SO₄^2-三个杂质指标进行节水优化应用，通过对该优化问题KKT条件进行求解从而实现模型的简化，优化后水网络新鲜水取用量减少6.7%、排污量减少62.9%。通过案例研究表明，构建的基于“供-用-耗-排”过程的再生循环水网络模型是成功的，可实现火电厂多杂质指标、复杂系统考虑再生循环的水网络节水优化设计，解决了水网络集成优化方法在火电厂应用中单元间回用过程描述不够准确以及再生单元描述不适用于节水改造情景的问题。     

过程工业水分配网络的研究进展

回顾了水分配网络的发展历程,介绍了水分配网络的用水网络和废水处理网络2个子系统的研究进展,阐述了图解方法、数学优化法等用水网络综合方法的发展状况,并对水分配网络设计中多杂质和热集成等方面的问题进行了展望。     

A global optimal formulation for the water integration in eco-industrial parks considering multiple pollutants

A mathematical programming formulation for the water integration in eco-industrial parks considering streams with several pollutants is presented. The formulation is based on a superstructure that allows the wastewater reuse in the same plant, the water exchange with different plants, and a shared set of interceptors that must be selected to determine the network configuration that satisfies process equipments and environmental constraints. The model formulation considers wastewater with several pollutants, and optimizes the network according to the minimum total annual cost, which includes the costs of fresh water, piping and regeneration. A new discretization approach is also proposed to handle the large set of bilinear terms that appear in the model in order to yield a near global optimal solution. The results obtained in several examples show considerable savings with respect to the solutions of the individual plant integration policy commonly employed for these types of problems.     

考虑非等温混合的能量集成多杂质水网络优化设计

提出了一种分步综合多杂质体系水网络和换热网络的新方法。对于水网络,考虑进入操作单元的新鲜水与回用水之间的非等温混合,确保流股间的直接热回收;对于换热网络,可以只考虑水网络中的新鲜水和回用水流股之间的换热匹配。采用无进化次数的改进粒子群算法对本文建立的多杂质体系水网络非线性模型和换热网络混合整数非线性模型进行求解。实例表明,与不考虑非等温混合时比较,考虑非等温混合时的最优网络结构更简单,且年度总费用要节省2.4%。因此,本文提出的方法在实际生产中有较好的可行性和有效性。     

Simultaneous integration of water and energy in heat‐integrated water allocation networks

This article proposes a new methodology for simultaneous integration of water and energy in heat‐integrated water allocation networks (WAHEN). A novel disjunctive model is first developed to determine an optimal water allocation network (WAN) where water and energy are integrated in one step. Based on the optimal WAN, a detailed heat exchanger network (HEN) to satisfy the utility target is then synthesized. Although the final network structure is obtained through two steps, the targets of freshwater and utility are optimized simultaneously. The proposed method has specific advantages. First of all, it can capture a tradeoff among freshwater usage, utility consumption, and direct heat transfer by nonisothermal mixing. Second, it can greatly reduce the complexity of subsequent HEN design. Finally, it is effective for simultaneous water and energy integration in large‐scale WAHEN systems. The advantages and applicability of this new method are illustrated by three examples from literature. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2202–2214, 2015     

Mathematical modelling of sustainable wastewater reuse networks considering CO<Subscript>2</Subscript> emissions

Water resource management poses a challenge in the process industry because a large amount of water must be used, even when prices increase. Companies struggle to minimize consumption by reusing wastewater, and the resulting water-reuse-network problem has been actively investigated. With the rising impact of global climate change, it is necessary to develop a sustainable methodology to reduce carbon dioxide emissions in the process industry. This paper proposes a mathematical model for sustainable water reuse networks that explicitly considers CO₂ emissions. To construct a sustainable network, emissions due to the construction and operation of the water network and additional water demand due to CO₂ capture facilities are incorporated. Actual case studies of steel manufacturing processes and eco-industrial parks are presented to illustrate the applicability of the model.     

Integrated water resource management through water reuse network design for clean production technology: State of the art

This article considers new and existing technologies for water reuse networks for water and wastewater minimization. For the systematic design of water reuse networks, the theory of the water pinch methodology and the mathematical optimization are described, which are proved to be effective in identifying water reuse opportunities. As alternative solutions, evolutionary solutions and stochastic design approaches to water system design are also illustrated. And the project work flow and an example in a real plant are examined. Finally, as development is in the forefront in process industries, this paper will also explore some research challenges encountered in this field such as simultaneous water and energy minimization, energy-pinch design, and eco-industrial parks (EIP).     

Simultaneous process synthesis,heat, power,and water integration of thermochemical hybrid biomass,coal, and natural gas facilities

A comprehensive wastewater network is introduced into a thermochemical based process superstructure that will convert biomass, coal, and natural gas to liquid (CBGTL) transportation fuels. The mixed-integer nonlinear optimization (MINLP) model includes simultaneous heat, power, and water integration that utilizes heat engines to recover electricity from waste heat and several treatment units to process and recycle wastewater. A total of 108 case studies are analyzed which consist of combinations of six coal feedstocks, three biomass feedstocks, three plant capacities, and two process superstructures. This study discusses important process topological differences between the case studies and illustrates each component of the process synthesis framework using the two medium-sized capacity case studies that have low-volatile bituminous coal and biomass feedstocks.     

Optimal design of single‐contaminant regeneration reuse water networks with process decomposition

Water network with regeneration schemes (e.g., regeneration reuse, regeneration recycling) can reduce freshwater consumption further than water network merely with direct reuse. Regeneration reuse, compared with regeneration recycling, can additionally avoid unexpected accumulation of contaminants. Owing to these features, process decomposition can help to reduce freshwater usage and wastewater discharge of regeneration reuse water systems and achieve the results, which graphical method delivers. In this article, the effect of decomposition on water‐using process and further on regeneration reuse water system is briefly analyzed on the concentration‐mass load diagram. Then a superstructure and three sequential mathematical models, which take process decomposition into account, are in turn developed to optimize single contaminant regeneration reuse water systems. By several examples, the reliability of the models is verified. Moreover, several decomposition strategies are summarized to realize the regeneration reuse water network, which attains the targets from graphical method. The results indicate that postregeneration concentration has a major impact on the scheme of process decomposition. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

双组分污染物系统用水网络优化研究

运用水夹点技术,对某石化企业9个用水操作进行用水网络优化研究。结果表明,单组分和双组分污染物用水网络初始设计分别节约新鲜水38.31%和19.17%;对初始设计用水网络的优化设计可简化用水网络,双组分污染物用水网络优化后回用管路数由11条减少为6条。水夹点技术在节约工业用水和废水减量方面具有实用价值和较好的应用前景。