【作者】 陈军；

【导师】 卢涛；

【作者基本信息】 北京化工大学 ， 化工过程机械， 2013， 硕士

【摘要】 随着全球人口的急剧增长以及经济的快速发展,淡水资源问题日益突显。海水淡化技术由于其原料资源广阔,可以源源不断为人类提供淡水资源,发展前景巨大。低温多效蒸发海水淡化技术,具有结垢风险性低、动力消耗小、热效率高以及可以利用热电厂低品位热源等优点,在工程实践中得到广泛的应用。本文以低温多效蒸发海水淡化系统为研究对象,介绍了顺流、平流和逆流三种常见的进料方式工艺流程。首先应用Aspen Properties物性模拟软件对海水的特殊物性进行模拟分析,低温多效蒸发海水淡化系统工艺流程操作线可以有效避开硫酸钙垢形成区,降低设备的结垢风险。通过建立与实际工程相应的Aspen Plus流程模拟图,在相同的操作工况下进行模拟计算,将模拟结果与文献进行对比,验证了所建工艺流程的可靠性和流程模拟的准确性。在加热蒸汽量和TVC引射率相同的情况下,应用等温差分配法对平流、顺流和逆流三种进料方式海水淡化系统工艺流程进行模拟计算,获得了造水比和比传热面积与蒸发器效数、浓缩比、效间温差和进料海水温度之关系。研究结果表明：蒸发器效数对系统的热力性能有显著影响,当效数较少时,采用平流进料方式较为合适；增大浓缩比可以提高造水比,且比传热面积变化不大；当浓缩比较大时,可采用顺流进料,以降低结垢风险；增大效间温差,会降低逆流进料方式的造水比,但会增加平流和顺流的造水比；提高进料海水温度可以提升系统热力性能,但进料海水温度受末效二次蒸汽温度的限制。针对顺流进料方式的工艺特点提出预热优化措施,在流程中抽取部分末效二次蒸汽对进料海水进行预热处理,可以显著提高系统的造水性能,应用Aspen Process Economic Analyzer经济评估软件对其经济投资进行分析,分析结果表明,增加预热流程可以缩短投资回报期,增加投资收益。本文应用Aspen Tech模块化软件研究的低温多效蒸发海水淡化系统工艺流程,对海水淡化技术的发展和应用具有一定的理论指导作用和实用价值。更多还原

【Abstract】 As the sharp increase of the world population and the rapid development of economy, water resources problem is increasingly highlighted. Due to its vast raw material resources, desalination technology has a huge development prospects, and can continuously improve freshwater resources for mankind. As a kind of desalination technology, low temperature multi-effect evaporation desalination has been widely used in engineering practice with a lot of advantages, such as low risk of scale, low power consumption, high thermal efficiency, and can take advantage of the low grade heat source of thermal power plant.Based on the low-temperature multi-effect evaporation desalination system as the research object, the thesis outlines the commonly used three feed water arrangements in multi-effect desalting systems, e.g. forward, backward, and parallel. First, apply the Aspen Properties analysis the special physical properties of seawater. The operation process line of low temperature multi-effect evaporation desalination system can avoid the calcium sulfate scale formation area, reducing the risk of equipment fouling. Using Aspen Plus, corresponding of the four-effect parallel feed LT-MED desalination system of SIDEM French Corporation process flow diagram is established. Simulate on the same operating conditions, and compared the results with the literature for demonstrating the reliability of the process and the accuracy of the simulation. Keeping the content of heating steam and gained output ratio of TVC in agreement, temperature distribution method is applied to simulate desalination system of the three feed water types. It achieves the relationship between the systems of thermodynamic performance with the number of effects, concentration ratio, temperature difference and feed seawater temperature in the three feed water types. The results show that better performance is obtained for the increasing effects, and the parallel feed mode is suitably selected for LT-MED with only several effects. The enhancement seawater concentration ratio results in corresponding increase of gained output ratio (GOR), and the specific heat transfer area has a little change. While the concentration is large, forward feed can be used for reducing the risk of scaling. As the temperature difference across the effects increases, the GOR of backward feed is decreased, parallel and forward are increased. For all feed types, increasing the feed seawater temperature can improve thermodynamics performance, but the feed seawater temperature is limited by evaporation temperature of the end effect.For the characteristics of forward feed process, preheating measure is put forward. Extracting the secondary steam of end effect to preheat the feed seawater, can significantly improve the system performance. Appling the Aspen Process Economic Analyzer to analyze its investment economic, it can shorten payback period and increase the investment returns.AspenTech modular software is applied in this thesis to study the low-temperature multi-effect evaporation desalination system technological process. It has a certain theoretical guidance and practical value for the development and application of desalination technology.更多还原