【作者】 王欢；

【导师】 楚纪正； 杨丽历；

【作者基本信息】 北京化工大学 ， 控制工程（专业学位）， 2017， 硕士

【摘要】 精馏塔是化学工业中应用最广泛和能耗最大的分离设备,对精馏塔塔板上气液两相流股接触情况以及塔板水力学性能的研究一直都是一个重要课题,掌握精馏塔的优化设计和合理的操作有助于提高分离效率。利用计算机技术,建立一个适用性广泛的精馏塔模型供生产和研究使用便显得尤为重要。本文对传统平衡级模型做了改进,通过短路气体概括平衡级模型与实际塔板的偏差,建立了一种实际的塔板模型:1、在现实精馏操作中,塔板上气液两相逆流接触传质,气液两相并未处于真正的热力学平衡状态,本文提出了一种带有短路量的塔板模型来描述与真实气液传质情况的偏差。上升气相被分为两部分,一部分完全与液体接触传质,称为浸入气体,另一部分不与液体接触,称为短路气体。2、结合传质理论和Stefan-Maxwell方程,气相传质过程近似为一个一阶过程,推导出了浸入气体的计算关联式。浸入气体流量公式含有一个可调节参数,该参数只和塔板结构有关,由生产数据校正。对于给定的塔板以及精馏物系,参数与操作条件是无关的。3、模型中还考虑到了漏液、雾沫夹带、塔板压降等水力学因素对塔板效率的影响,使用环己烷/正庚烷和乙醇/水两种不同物性的体系来模拟实验,实验结果与三种精确度高的效率模型非常吻合。更多还原

【Abstract】 Distillation column is the most widely used and big energy consuming separation equipment in chemical industry. It has been an important research subject to study the contact condition of gas-liquid flow and hydrodynamic performance of the trays. Optimal design and reasonable operation of the distillation column contribute to improve the separation efficiency. To use of the computer technology to establish a widely applicable distillation column model for commercial production and research use is particularly important. A modification is proposed to the conventional equilibrium stage model by including a shortcut gas flow in this paper and an actual plate model is established:1、In the actual operation, the gas streams countercurrent contact with liquid streams, but gas phase and liquid phase is not in the complete thermodynamic equilibrium state. This paper proposes a shortcut gas flow accounting for the deviation of the behavior of a real plate from the equilibrium assumption. Gas from the lower plate is divided into two parts: the immerging gas coming into close contact with the accumulated liquid, and the shortcut gas having no contact with the liquid.2、Combined with mass transfer theory and Stefan-Maxwell equation, the gas phase mass transfer is described as a first order process.In the immerging gas flow rate formula, there is one tuning parameter which depends only on the geometry of the plate and can be easily calibrated with production data. For a given plate working with a given system of substances, the proposed model is predictive in the sense that its only tuning parameter is independent of operating conditions.3、The hydrodynamic performances of the model including weeping,entrainment, pressure drop is also considered. In the simulation test with cyclohexane/n-heptane and ethanol/water distillation columns, the plate efficiency of the proposed model agrees very well with those calculated by three well-established efficiency correlations.更多还原