【作者】 乔红梅；

【导师】 胡仰栋；

【作者基本信息】 中国海洋大学 ， 环境科学， 2003， 硕士

【摘要】 水污染和水资源短缺是人类面临的重大问题。对于过程工业来讲，提高水资源的利用效率，改善用水网络的设计以节约新鲜水，减少废水排放是值得认真研究的课题。本论文对过程工业中用水网络的优化设计进行了研究，其中对于有温度要求的工业用水过程的设计进行了初步探索。主要内容有以下几点： 1、本文利用线性规划法对确定用水过程最小用水量的问题进行了研究。分别研究了单组分再利用、再生再利用、再生循环最小用水量问题，把它们归结为线性规划来求解，其中对于再生再利用和再生循环分别提出了两步线性规划法。对于再生再利用过程，第一步建立线性规划1，以确定整个过程的最小新鲜水和相应的最小再生水用量，第二步将第一步所获得的整个过程的最小用水量和相应的最小再生量以及最低再生浓度区间作为已知量，采用与线性规划1同样的约束建立线性规划2，再次求解即可得最低再生浓度C_b。 2、本文发现再生再利用过程的最小用水量和再生浓度之间存在两种关系，这两种关系表明获得最小新鲜水用量和再生量的最低再生浓度存在两种可能：夹点处和夹点之上，从而得出了与文献“夹点处再生能获得最小新鲜水用量”不同的结论，即夹点处再生未必总能获得最小新鲜水用量。例子求算结果表明本文方法是有效和简便易行的。 3、本文对多组分用水系统的优化设计即废水最小化问题进行了研究，在逐步线性规划法的基础上，提出了逐步非线性规划法的过程优化设计方法。新方法首先按每个组分的限定浓度对各操作进行排序，然后对每个操作序列进行逐级优化匹配。然后通过比较选出一个用水量最小的设计，作为过程的最终设计。其中，对单元操作ⅰ的优化匹配就是解非线性规划问题。例子计算结果表明本文算法是简捷的。 4、对于有温度要求的工业用水过程，往往既要消耗大量的水也要消耗大量的能量，然而长期以来用水网络的热集成问题却往往被人所忽略。本文对于含有热集成的单组分用水网络进行了初步探讨，提出了两阶段设计法的简化设计策略，以实现整个过程的用水最小化和用能最小化。本文只研究了第一阶段的设计，第二阶段将在以后的研究中探讨。第一阶段以同时的用水量最小和(火用)损最小为目标，采用逐级优化匹配的设计方法来设计用水网络，把整个用水系统分为两个层面来求解。第一个层面为用水单元层面，采用序列两步线性规划法确定用于每个单元用水操作的各股水源流量以及相应的初始温度和目标温度(包括新鲜水和废水)，以实现单元用水操作的用水量最小和朋损最小化。第二个层面为整个用水系统层面，采用逐级优化匹配设计的方法来完成整个用水网络的设计，以实现整个用水系统的用水和朋损最小化。第一个层面和第二个层面求解紧密结合共同完成问题2的用水系统第一阶段的设计。例子求解结果表明本文所提方法是简单有效的。更多还原

【Abstract】 Water pollution and scarcity of water is a life-and-death problem that human being is facing, it is worthy of investigation evolving water-using processes to reduce both fresh water consumption and wastewater production. This paper will focus on the optimization design of water-using networks, in which the design of a set of water-using processes requiring water of a certain temperature is approached preliminarily. The key ideas in the paper are extracted and listed below:1. A new method is addressed for determining minimum flowrate of fresh and regenerated water in water-using processes. This paper approaches reuse, regeneration reuse, regeneration recycling process for single contaminant respectively, the mathematical formulation of these synthesis problems leading to a linear programming, of which the two-step linear programming are presented respectively for regeneration reuse and regeneration recycling. For regeneration reuse, in step 1, the linear programming 1(LP1) is established, which targets the minimum flowrate of fresh water and corresponding regenerated water. In step 2, based on the minimum flowrate of fresh water and corresponding regenerated water along with the interval in which C’b exists, the linear programming (LP2) with the same constraints with LP1 is established, which can be easily solved to yield the value of the Cb.2. In addition, two different relationships between the fresh water flowrate required and inlet concentration to regeneration are found out, which indicate two possibilities with Cb : at pinch or above pinch, therefore a new conclusion is drawn, which differs from "Regeneration of water at pinch minimizes fresh water flowrate" derived by some papers and points out that in some cases, regeneration at pinch point can’t always minimizes fresh water flowrate. One example is solved to demonstrate the advantage and validity of the new method.3. This paper approaches the optimized design of water-using systems of multiple contaminants, i.e. wastewater minimization. Stem from the step-by-step linear programming method, a modified method is addressed, which we name step-by-step non-linear programming method. From the beginning, the processes are collated according to the limiting operating data of each contaminant, and then the matchingbetween the rich streams and lean steams (water sources) is optimized step by step in accordance to the collated processes for each process sequence, ultimately the design of water-using network which minimizes the fresh water usage is selected by comparison. Two examples are solved to demonstrate the effectiveness and convenience of the new method.4. Water and energy are among the most highly used commodities for water-using system requiring water of a certain quality and temperature, however, the influence of heat integration on the solution of water-using systems has been ignored for a long time. This paper approaches the design of single contaminant water-using system requiring water of a certain quality and temperature, and introduces a two-stage reduced design approach for the design of water-using networks targeting minimum freshwater usage and minimum energy consumption in process plants by water reuse and energy integration. This paper focuses on the research of the design method in stage 1, and the design method in stage 2 will be researched later on. In stage 1, the step-by-step optimization matching method is presented to design the water-using network, which targets minimum freshwater usage and minimum exergy loss and resolves the water network design into two layers. The first layer is the water-using unit, in which, the sequential two-step linear programming is used to determine each water source flowrate, the corresponding original temperature and target temperature for each water-using unit, which targets minimum freshwater usage and minimum exergy loss of the water-using unit. The second layer is the overall water-using system, in which, the step-by-step optimization matching meth更多还原