【作者】 陈海胜；

【导师】 黄克谨；

【作者基本信息】 北京化工大学 ， 控制科学与工程， 2010， 硕士

【摘要】 虽然理想内部热耦合精馏塔比常规蒸馏塔具有更大的节能潜力,但是由于其精馏段与提馏段之间的热耦合设计与实施困难重重,使得它至今难以石油与化工生产过程中应用并推广。因此,为了解决这一难题,有必要对其内部热耦合的结构或传热方式进行深入系统的研究。现有的关于内部热耦合结构的研究结果中,大部分都对内部热耦合精馏塔耦合部分的结构进行了改进,例如：日本的同心圆柱式传热结构和多同心圆柱捆绑式传热结构、美国的板翅式内部传热结构和隔离壁式内部传热结构、英国的塔板式内部传热结构以及欧盟的热交换屏式传热结构等,但这些结构都没有在实际石油化工生产过程中广泛应用,究其原因,可以总结为两点：一,内部热耦合精馏塔的内部传热装置的面积大小受限于精馏塔塔壳的大小,使得传热面积的安排非常困难；二,几乎所有的结构设计构造复杂,造价昂贵,不符合投资者的要求。因此,传热结构的设计问题仍然是内部热耦合精馏塔能否得到推广的关键。本文提出了一种新型的理想内部热耦合精馏塔的简化结构(SIHIDiC,以下简称简化结构),将精馏段和提馏段之间的传热结构安装在精馏塔的外部,换热器个数因此能够合并而大幅度的减少,巧妙地避免了传热面积受到精馏塔的大小限制等问题。本文认为仅需三个(或更少)的换热器即可近似实现精馏段和提馏段之间的热传递,其中一个换热器安装在精馏段和提馏段的顶部之间,以实现精馏塔的零外部回流操作；一个换热器安装在精馏段和提馏段的底部之间,以实现精馏塔的零外部回热操作；一个换热器安装在精馏段和提馏段的中部之间,分别为两段产生二次下降液量和上升蒸汽。由于三个换热器的位置与大小是影响内部热耦合精馏塔热力学效率的关键变量,而它们之间有着极其复杂的关联,因此,本文还开发了一个递进式的综合与设计方法来权衡它们之间的关系。为了更好的研究理想内部热耦合精馏塔的简化结构,本文建立了常规精馏塔和理想内部热耦合精馏塔的稳态数学模型,并同时提出了基于TAC的综合与设计方法和基于T-H的热力学分析方法。本文选择了一个较难分离的二元混合物系乙烯／乙烷和一个相对较易分离的二元混合物系苯／甲苯来研究常规精馏塔、理想内部热耦合精馏塔及其简化结构的稳态性能,并通过简化结构与常规精馏塔的比较证实了简化结构具有与理想内部热耦合精馏塔更大的节能潜力。实验证明,简化结构可以很好的近似理想内部热耦合精馏塔,前者与后者相比甚至具有更小的固定投资和操作费用。基于TAC的系统综合与设计方法可以适用于不同的分离系统,能够显著发挥系统的节能效果,且该方法简单易行。更多还原

【Abstract】 Although the ideal heat-integrated distillation column (ideal HIDiC) is much more thermodynamically efficient than its conventional analogues, its applications in the chemical and petrochemical process industries have been restrained. The reason can be attributed to the great difficulties and complexities in the design and implementation of internal heat integration between the rectifying section and the stripping section because all the attempts arrange internal heat transfer within the column shell so far. For the avoidance of these difficulties, a breakthrough in process synthesis and design must be made in these aspects.In this dissertation, internal heat integration between the rectifying section and the stripping section is suggested to move to the outside of the column shell, and this leads to the creation of a novel simplified configuration for the ideal HIDiC, termed the SIHIDiC. Only are three or even fewer internal heat exchangers used to approximate the internal heat integration. The top internal heat exchanger is arranged between the tops of the rectifying section and the stripping section respectively, enabling the SIHIDiC to operate in a reflux-free operation mode. The bottom internal heat exchanger is fixed between the bottom of the rectifying section and the stripping section respectively, enabling the SIHIDiC to operate in a reboil-free operation mode. The intermediate internal heat exchanger is located between the middles of the rectifying section and the stripping section respectively, generating secondary or additional reflux flow for the rectifying section and vapor flow for the stripping section. The locations and sizes of the three heat exchangers are key decision variables for process synthesis and design and should be considered to enhance thermodynamic efficiency in process development.A simple stepwise procedure is thus derived for process synthesis and design and the SIHIDiC is evaluated through intensive comparison with the conventional distillation column and the ideal HIDiC in terms of the separations of an ethylene/ethane and benzene/toluene binary mixtures. The results obtained indicate that the SIHIDiC could be an excellent candidate to approximate the ideal HIDiC with somewhat similar (if not smaller) capital investment and operating cost and it can implement in the chemical and petrochemical process industries.更多还原