多杂质水和能量系统集成

发布时间：2018-02-20 19:18

本文关键词： 系统集成技术水网络换热网络再生循环系统操作弹性　出处：《河北工业大学》2015年博士论文　论文类型：学位论文

【摘要】：水资源和能源对于人类社会及其经济活动发展起着极其重要的作用。随着水资源和能源的日益匮乏,水资源和能源优化利用成为最近研究的热点。作为减少新鲜水和能量消耗的有效手段之一,过程系统集成技术广泛应用于过程集成与设计优化。本文将对水系统集成和同时考虑水和能量的集成系统进行研究,主要内容包括如下几部分:第一章,简要概述了近年来水和能量集成系统的主要研究方法,并对本课题的研究意义和背景作了简要论述。第二章,水系统集成即是采用科学方法确定水流之间的合理分配,以实现水资源消耗最小化的目标。本章研究了具有中间水道的再生循环水网络设计。对于包含固定杂质移除率模型的水网络,提出初始再生浓度的估算方法;然后依据浓度势概念和用水过程的极限流量将所有用水过程划分为三部分;根据源水流浓度势值,确定构成中间水道的源水流,形成水网络初始结构。采用迭代方法对初始网络结构进行调整,计算收敛后即可获得最终水网络设计。本方法适用于包含固定杂质负荷过程与固定流量过程的复杂水网络设计。实例研究结果表明,运用本方法能够显著减少新鲜水消耗量和再生水流量,且计算过程简单。同时本文方法中每步均具有明确的工程意义。第三章,针对水和能量同时集成的单杂质系统,本文提出新的设计方法。首先根据用水过程的操作温度确定各过程的新鲜水温度,然后根据用水过程的浓度和温度因素设计水网络:(i)由各用水过程的极限进出口浓度确定过程的执行顺序;(ii)将源水流按浓度由低到高的顺序依次满足各需求水流,当源水流浓度相同时,温度将作为主要考虑因素;(iii)依次执行各用水过程获得水网络设计。最后,在所得水网络基础上设计相应的换热网络。实例计算表明,采用该方法获得的网络设计结果可与采用数学规划法获得的文献结果相媲美,且网络结构更加简单。第四章,对于水和能量同时集成的多杂质系统,设计过程分为两步:首先结合过程的浓度和温度条件对多杂质用水网络进行设计,然后根据用水网络结构设计相应的换热网络。在换热网络设计过程中,采取两种设计策略:(i)高温过程自身加热其进口水流,这样既保持了自身循环加热网络结构简单的特点,又解决了换热器数目较多的问题;(ii)流股在非等温混合前首先进行间接换热,使冷热流股的温度差值不至于过大,进而降低由于混合造成的能量降级。提出冷热流股的换热规则,提高能量的利用效率并减少外部能量消耗。分别考虑这两种设计策略,获得换热网络设计。实例计算结果表明,采用上述方法设计所得网络结构比文献结果更加简单。第五章,对于包含能量集成的用水系统,用水过程与换热网络高度集成,这给系统操作和控制带来新的问题。本文研究了此类系统的操作弹性问题。首先,根据用水过程的温度及使用新鲜水的状况确定系统的关键过程与关键水流;其次,提出关键水流影响系数的新概念用于计算关键水流正常操作温度区间;最后,研究了如何调整现有系统,增大关键水流正常操作温度区间,提高系统操作弹性。实例计算表明,采用本文提出的方法可以有效减少系统的公用工程消耗和换热器数量,同时使系统操作弹性有所提高。第六章,结论。
[Abstract]:Water resources and energy for the human society and economic development plays an extremely important role. With the increasing scarcity of energy and water resources, water resources and energy utilization has recently become a hot research. As one of the efficient ways to reduce fresh water and energy consumption, process integration technology system is widely used in process integration and design optimization. This article will focus on the water system integration and considering the integrated system of water and energy are studied. The main contents include the following parts: the first chapter, a brief overview of recent water and energy integration system the main research methods in this paper and the research background and significance are introduced briefly in this paper. The second chapter, namely water system integration is the use of scientific methods to determine the reasonable allocation of water between the water, in order to achieve the goal of minimizing the consumption of resources. This chapter studies with water mains recycling water network Design for impurity removal rate. Contains fixed model of water network, proposed method to estimate initial concentration of regeneration; and then based on the concentration limit flow and water potential concept will process all the water process is divided into three parts; according to the source water concentration potential value, to determine the composition of intermediate water source water channel, the water network structure. The initial formation the iterative method to adjust the initial network structure, obtained the final water network design can design complex water network convergence. This method is suitable for containing a fixed load and fixed impurity discharge process. The results show that using this method can significantly reduce the consumption of fresh water and recycled water flow, and the calculation process is simple at the same time. This method has clear engineering significance of each step. The third chapter, according to the water and energy at the same time integrated single impurity system, this paper presents a new design method. According to the water temperature to determine the process of the operation of the fresh water temperature of each process, then according to the design of water network concentration and temperature factors of water: (I) to determine the order of execution of the process by the limit water process of import and export concentration; (II) the source of water in concentration from low to high order to meet the demand when the water source water at the same concentration, the temperature will be a major consideration; (III) followed by the implementation of the water process water network design. Finally, the design of heat exchanger network based on the corresponding water network. Examples show that the results obtained by using the method of network design can be comparable with that obtained by mathematical programming method results in the literature, and the network structure is more simple. In the fourth chapter, for water and energy and integrated multi contaminant system design process is divided into two steps: firstly, combined with the process of concentration and temperature conditions of impurities The design of water network, then according to the structure of water network design of heat exchanger network. In the design process of heat exchanger network, adopt two design strategies: (I) high temperature heating process itself the import flow, so as to maintain its own circulation characteristics of heating network has the advantages of simple structure, and solves the problem of heat exchanger for more number the problem; (II) stream in non isothermal mixing before the first indirect heat transfer, the temperature difference between the hot and cold streams is not too large, then reduce the energy degradation caused by the mix. The hot hot and cold stream changing rules, improve energy efficiency and reduce the external energy consumption. Consider the two the design strategy respectively, obtain the design of heat exchanger network. The calculation results show that the method of the design of network structure is more simple than the results in the literature. The fifth chapter is to contain the energy integrated water system, water and heat process The thermal network is highly integrated, it brings new problems to the operation and control system. This paper studies the operating flexibility of this kind of system. Firstly, according to the key process of the process of using water temperature and using fresh water system and determine the key flow; secondly, put forward a new concept of critical flow influence coefficient is used to calculate the critical flow in normal operation the temperature range; finally, on how to adjust the existing system, increase the key flow normal operating temperature range, improve the operation flexibility of system. The calculation results show that this method can effectively reduce the utility system less consumption and the number of heat exchangers, and the operation has improved elastic system. The sixth chapter is the conclusion.

【学位授予单位】：河北工业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ085

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