水夹点分析与数学规划法相结合的用水网络优化设计

提出了水夹点分析和数学规划法相结合的用水网络最优设计法。水夹点分析基于对过程用水的理解,获得新鲜水用量目标并给出用水网络设计的基本规则。在此基础上建立过程使用新鲜水、排放废水和回用的各种可能匹配方案的用水网络超结构及其MINLP模型。既避免了用水夹点综合设计用水网络得不到真正意义上的最优解,又在一定程度上防止超结构规模过大,MINLP维数太高,求解困难。采用通用代数建模系统GAMS得到用水网络最优设计方案。文献中的应用实例表明,本文所提方法可充分发挥水夹点分析确定新鲜水用量或回用结构的简洁实用性和超结构MINLP寻求最佳方案的优点。     

水夹点分析与用水网络优化设计方法

水夹点技术作为一种有效的优化方法在用水网络优化、水源节约及废水减量等方面应用,能收到良好的经济效益和环境效益.作者介绍了水夹点技术的基本原理、应用实例以及进一步网络优化设计方法.     

应用夹点技术确定再生水用量

工业节水及废水减排已成为过程工业持续发展的前提之一。运用目标导向的夹点分析技术对过程用水网络系统进行系统地分析,可确定过程用水、再生水用量和废水排放量的最小目标。以固定再生出口浓度为基准,提出基于累积流量-累积污染质量负荷组合曲线图的夹点分析方法来确定用水网络的最小再生水流量,并给出了详细计算步骤和案例验证。     

水级联法确定间歇用水过程的夹点及废水最小化

利用水级联分析法对间歇过程用水网络进行研究,确定过程的用水夹点及最小新鲜水用量和最小废水排放量,提出了间歇用水过程的全局夹点的概念,考虑了用水过程的流率限制,在水级联表格中用流率替代了传统水级联分析法中的传质量,识别过程中每个时间段的局部夹点及公用工程目标,通过全局夹点和局部夹点的比较,指出过程的用水瓶颈,设置储罐打破瓶颈,使用水网络公用工程目标最小化。通过实例对水级联分析法进行了详细的阐述,计算结果与文献一致,表明该方法是一种易于理解、直观且简便有效的确定间歇过程用水网络的夹点及最小公用工程的方法。     

有最大入口浓度限制的单杂质废水处理网络设计

分布式废水处理系统集成的本质特征之一是通过最大程度减少不必要的水流混合量而降低系统的总处理量。根据这一思想,提出了一种基于启发式规则的方法设计废水处理单元有最大入口浓度限制的单杂质废水处理系统。首先依据提出的规则确定处理单元的执行顺序,并在此基础上建立初始网络结构;然后通过计算确定最终网络结构。在设计过程中,上述规则的运用和最终网络结构的确定需要与杂质负荷平衡、夹点确定等废水处理网络设计的基本概念以及入口浓度限制条件相结合。对文献实例的研究表明,结果与数学规划法的求解结果相当,但设计过程更为简单且具有明确的工程意义。     

Raw material management networks based on an improved P-graph integrated carbon emission pinch analysis (CEPA-P-graph) method

Raw material management plays an essential role in the environment production and carbon emission problem. A P-graph is an effective tool that can be used to solve the raw material management problem. However, raw material management based on the P-graph is complicated and inaccurate. Therefore, this paper proposes an improved P-graph integrating carbon emission pinch analysis (CEPA-P-graph) method to resolve raw material management problem with simpler structures and less results. The proposed method is applied in raw material planning in terms of the regional energy planning problem, and two ethylene plants under carbon emission constraints are examined. As the parameter information of the problem is utilized by pinch technology, the search domain of structure optimization is further reduced, and the computing complexity is reduced, while the advantages of the P-graph multi-solution are guaranteed. The experimental results demonstrate the validity of the proposed method. Furthermore, the CEPA-P-graph could reduce the complexity of solution structure generation by ~70% and reduce the carbon emission per unit product by 17%.     

基于杂质赤字的再生回用水网络集成图示法

将氢网络中基于剩余率的集成优化法扩展至水网络，以杂质浓度为基础进行分析，提出了基于杂质赤字的再生回用水网络图像集成优化方法。该方法无需图像试差和迭代，通过构建浓度-流量图和杂质赤字图，可确定未考虑再生回用的水网络夹点位置及最小新鲜水用量。并在此基础上，考虑再生装置和水网络的优化以及二者的集成，分析水网络的新鲜水节省量与杂质脱除率、再生水源流量及再生废水浓度的定量关系；构建定量关系图确定最小新鲜水用量随各参数的变化关系、夹点位置、最大新鲜水节省量以及一定再生条件下的极限及最优提纯参数。案例分析表明，该方法简单、高效，对于各工况下的水网络，均可使新鲜水消耗量及废水排放量减小，为工艺设计和操作提供重要的参考。     

Rigorous algorithmic targeting methods for hydrogen networks—Part I: Systems with no hydrogen purification

Hydrogen utility consumption minimization is one of the key strategies for reducing refinery operating costs. Process integration techniques have been widely accepted as an effective tool for reducing hydrogen consumption. To date, various pinch based conceptual methods have been developed. Applying the pinch analysis is simpler than solving the mathematical model. However, the relationship between the pinch simplification and the mathematical model has seldom been addressed. In addition, existing pinch analysis paid little attention to the rare but realistic cases of threshold problem. In this article, the original mathematical model is associated with the pinch concept by proving simplified equivalent formulations. A mathematically rigorous systematic targeting approach is then obtained by mathematical deduction. The proposed method combines pinch insight with a rigorous mathematical optimization technique. The proposed method addresses both threshold and pinch problems, and initially the analysis is restricted to systems with no purification unit.     

Synthesis of Water Utilization System Using Concentration Interval Analysis Method （ Ⅰ ） Non-Mass-Transfer-Based Operation

A strategy for water and wastewater minimization is developed for continuous water utilization systems involving fixed flowrate（non-mass-transfer-based）operations,based on the fictitious operations that is introduced to represent the water losing and/or generating operations and a modified concentration interval analysis（MCIA） technique.This strategy is a simple,nongraphical,and noniterative procedure and is suitable for the quick yields of targets and the identification of pinch point location.Moreover,on the basis of the target method,a heuristic-based approach is also presented to generate water utilization networks,which could be demonstrated to be optimum ones. The proposed approaches are illustrated with example problems.     

基于浓度间隔分析的用水系统集成(Ⅰ)非传质操作

A strategy for water and wastewater minimization is developed for continuous water utilization systems involving fixed flowrate(non-mass-transfer-based)operations,based on the fictitious operations that is introduced to represent the water losing and/or generating operations and a modified concentration interval analysis(MCIA) technique.This strategy is a simple,nongraphical,and noniterative procedure and is suitable for the quick yields of targets and the identification of pinch point location.Moreover,on the basis of the target method,a heuristic-based approach is also presented to generate water utilization networks,which could be demonstrated to be optimum ones. The proposed approaches are illustrated with example problems.     

再生循环水系统引入再生过程后夹点位置

引入再生循环的最优水系统可以最大限度地节约新鲜水的用量和减少废水的排放,是当前节水技术研究的重点。用水系统引入再生过程后,极限供水线会发生变化,从而水系统夹点个数以及位置都可能会发生变化。运用前人总结出的再生循环过程最佳供水线的构造方法,分析影响引入再生过程后夹点位置变化的因素,发现引入再生过程前后夹点位置的变化情况与以下因素有关：极限复合曲线上的凹点位置以及凹向极限供水线的程度和最高浓度用水单元水流率与新鲜水流率的关系,并分析得出夹点位置的变化规律,从而为用水网络的分析和设计提供理论性的指导。     

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。     

用夹点分析法对换热网络用能的诊断和调优

本文概述了夹点技术、夹点分析法的发展概况。用问题表格法算出了某炼油厂常压精馏换热网络过程的夹点，用夹点分析法之一——“格子图”查出了跨夹点的换热器，经计算给出了有较大节能效果的改造方案。     

过程全局夹点分析与超结构MINLP相结合的能量集成最优综合法

提出了过程全局夹点分析与超结构混合整数非线性规划 (MINLP)相结合的能量集成最优综合法 .各单过程内部换热优化匹配后 ,进行各过程剩余冷、热负荷与公用工程系统的全局夹点分析 ,确定全局热集成目标 ,在此基础上建立包含过程剩余热负荷产生各等级蒸汽、剩余冷负荷使用各等级蒸汽加热的各种可能匹配方案的公用工程换热网络超结构及其MINLP模型 ,采用混合连续进化算法求解得到过程与公用工程换热网络最优改造方案 .大型乙烯装置能量集成应用算例表明 ,可充分发挥全局夹点分析法确定改造目标的简洁实用性和超结构MINLP寻求最佳方案的优点     

A numerical‐indicator‐based method for design of distributed wastewater treatment systems with multiple contaminants

In the design of distributed wastewater treatment systems with multiple contaminants, it is very important to minimize unnecessary stream mixing to reduce total treatment flow rate as much as possible. A new numerical indicator, total mixing influence potential (TMIP), to reflect the influence of the stream mixing caused by performing a process on the total treatment flow rate of a distributed wastewater system is introduced. In design procedure, the TMIP value is calculated based on pinch principle. The process with the smallest TMIP value will be performed first. The results of a few literature examples show that designs with very low (even minimum) total treatment flow rates can be obtained with the method proposed. In addition, the method proposed is simple and of clear engineering insight. The calculation effort does not increase significantly when the number of streams, contaminants, and/or treatment units increases. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3223–3231, 2015     

Generalized Pinch Analysis Scheme Using MATLAB

In pinch analysis, the calculations needed for determining pinch temperatures and minimum utility requirements are simple and can be done manually in case of a small number of streams. However, in real‐scale industrial problems, the calculation can become tedious and very much time‐consuming. A generalized low‐cost and user‐friendly scheme for pinch design using MATLAB is proposed. This scheme is tested for several problems for accuracy and robustness to determine hot pinch temperature, cold pinch temperature, minimum cooling load, and minimum heating load using the temperature interval method. The solutions developed by the proposed scheme are mirror images of solutions found by applying a rigorous procedure.     

热集成复杂精馏系统综合的研究

将夹点分析法应用于热集成复杂精馏系统综合的换热网络设计中,避免了以换热网络结构作为独立变量,建立了一个以预分馏塔组分回收率、回流比及操作压力为连续变量,以分离序列和热耦合方式为离散变量的混合整数非线性规划(MINLP)模型。该模型用改进的模拟退火算法求解,可同时得到优化的流程结构和操作参数。对多个五组分混合物分离问题进行了求解,并对不同优化方案的优化结果及其经济性作了比较和分析,结果表明采用热集成复杂精馏塔流程可以显著地降低系统的总费用,还表明该方法是求解热集成复杂精馏系统综合问题的有效方法。     

Synthesis of optimal heat-induced separation networks

In this work we introduce the novel problem of synthesizing heat-induced separation networks (HISENs). The essence of HISEN synthesis is to reduce the concentration of a certain component in a number of rich (typically waste) streams from a set of supply compositions to a set of target compositions by using a number of heat-induced separators. A heat-induced separator is any indirect contact unit which employs an energy-separating agent (ESA) to affect separation via phase change. Examples of these systems include condensation, crystallization, vaporization and drying. By combining phase-equilibrium data with enthalpy balances, we develop pinch diagrams that can be used to determine the minimum operating cost of the system. There are two distinctive characteristics associated with the pinch diagrams for the HISENs. First, the location of the pinch point is not restricted to the supply temperatures of streams. Second, heat-induced separators may straddle the pinch point even for networks featuring the minimum cost of energy-separating agents. A systematic procedure is presented to address these characteristics and to synthesize a cost effective network of heat-induced separators. The problem is formulated as an optimization program. A solution procedure that is guaranteed to identify the global solution is devised to solve the problem. In addition, a slightly revised formulation is developed to incorporate the effect of stream bypass/mixing. Several case studies are tackled using the proposed procedures.     

高浓度尿素废水泠冻浓缩极限

冷冻浓缩技术是处理尿素厂废水和尿液等高浓度尿素废水的有效方法之一,浓缩极限的确定则是预测和评价该工艺最高水回收率和工作效率的必要条件.以尿素溶液为研究对象,采用差示扫描量热技术分析了溶液在冷冻过程中的相态变化规律,通过冷冻试验确定了溶液发生尿素共晶析出时的浓度;以尿液为对象,研究了确定高浓度尿素废水冷冻浓缩极限的方法.研究结果表明：尿素废水在达到浓缩极限之前,当尿素浓度高于26.3%时,继冰晶析出之后会共晶析出尿素;尿素废水在浓缩极限处呈玻璃态,由差示扫描量热分析可确定废水玻璃化转变温度、推算冷冻浓缩工艺最高水回收率;尿液的玻璃化转变温度为-108.33 ℃,相应的溶液浓度为57.92%,冷冻浓缩可达到的最高水回收率为97.75%.     

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。