天然气液化工艺模拟与分析

【作者】 位雅莉；

【导师】 蒋洪；

【作者基本信息】 西南石油学院 ， 油气储运工程， 2004， 硕士

【摘要】 我国天然气液化技术是一项新兴的技术，正在迅速发展，但与国外天然气液化技术相比，国内天然气液化技术才刚刚起步，差距较大。本文从热力学角度出发，对天然气低温液化流程模拟与优化进行了详细的研究。 文中首先论述了国内外天然气液化技术的现状和发展趋势，并详细阐述了液化技术原理，通过对各种常见的现代天然气液化流程特点的分析，给出了流程的选择和设计原则；确定了以SRK方程和P-R方程作为计算天然气液化相平衡的基础模型，并结合精度较高的LKP方程来计算混合物的焓和熵，提高了整个流程模拟的精度；利用模块化思想，对天然气液化流程中压缩机、混合器、多股流换热器等设备热力过程进行了模拟，通过其在流程计算中的使用，效果良好；混合制冷剂循环(MRC)液化天然气流程是目前世界上应用最广泛的工艺，本文对带回热和无回热的两种液化流程分别进行了模拟计算，比较了两种流程中压缩机耗功，丙烷预冷量、制冷剂流量、各换热器的换热量等表示流程性能的参数，并分析了混合制冷剂参数对流程性能的影响，得出了降低流程能耗、增加可行性的结论；给出MRC液化流程的优化模型，并提出以惩罚函数法作为优化算法，结合各种约束条件，对流程进行了优化计算，效果良好；用灰箱模型对天然气液化流程进行了(火用)分析，通过计算确定了流程中能耗大的薄弱环节，分析其(火用)损原因，并提出了若干项减少(火用)损的有力措施。更多还原

【Abstract】 The liquefaction of natural gas is now a new and advanced technology. But there are big difference in technology of natural gas liquefying between our country and developing countries. In text, the research in simulation and optimization of the LNG are studied from the thermodynamics.Firstly, the paper discussed the current development of LNG and its trend in the future, and the principle of the liquefied technology to the natural gas is introduced and the fundamental regulation for the choice and design is given out through the analysis to those characteristics that all kinds of modern common-using liquefied cycles in use of natural gas have. In paper, the SRK and the P-R are regarded as the calculation model of the vapor-liquid equilibrium, and the LKP equation is used to calculate the enthalpy and entropy of hydrocarbons, by those equations simulation calculations of processes are resolved. By thoughts of module, the mathematic models for the equipments in the simulation of the liquefied process of natural gas are established, they have good effects in the simulation. In paper, two MRC processes are simulated, one is the no turn round heat exchange process, the other is having turn round heat exchange process, and the power of the compressor, the cooling provided by the propane cycle, the flux of the refrigerant, the exchanged heat of each heat exchanger of two processes are analyzed contrastively. The influences by which the process’s parameters have effects on the performance of the typical liquefied process are exactly and fully analyzed. According to that, energy loss can be reduced. At the same times the model of the optimization to the liquefied process are given, the SUMT is used as the optimized method, combined with the constraints, the calculation result is good. In addition, the exergy analysis of the cycle and equipments are carried out based on the thermodynamic analysis in the paper, and the cause of the exergy loss is analyzed and some effective measures of reducing the loss are mentioned.更多还原