天然气液化工艺流程模拟优化及用能分析

发布时间：2018-07-10 05:38

本文选题：液化天然气 + 丙烷预冷混合制冷剂循环　；参考：《西安石油大学》2015年硕士论文

【摘要】：近年来,在治霾降污的压力下,呼声高涨的环境治理倒逼能源向清洁化方向加快发展。随着低碳资源的大力开发利用,我国能源消费结构得到进一步优化,煤炭在一次能源消费结构中的比重下降,优质、清洁、高效的天然气消费占比上升,且消耗量呈日益增大的趋势。本文阐述了天然气液化技术的现状和发展趋势,简要介绍了几种天然气液化流程的优缺点,并进行技术经济比较,优先选择目前国内外应用最广泛的新型高效流程——带丙烷预冷的混合制冷剂循环液化流程作为模拟流程。根据天然气和混合制冷剂的热物性,为满足计算精度要求,工质相平衡特性选用PR方程,焓熵等热物性选用LKP方程。通过ASPEN HYSYS软件进行模拟计算,得到的结果和已知实验数据的对比结果在误差范围内,说明模拟过程中选用的热力学方程是合适的。利用模块化思想对流程中每一处设备进行模拟。采用ASPEN HYSYS软件搭建流程,对循环中的压缩机、多股流换热器、节流阀和混合器等模块进行详细的参数设置,最终得到收敛的稳态模拟系统。在稳态流程工况下,分别模拟了混合制冷剂组分、高低压、温度,原料气压力、温度,以及丙烷预冷后温度对流程的影响,得到合理的制冷剂配比和科学的流程参数:混合制冷剂最佳配比是甲烷为0.436(摩尔分数,下同)、乙烷为0.393、丙烷为0.099、氮气为0.072。在此基础上,对流程关键设备进行有效能分析,进一步优化流程,达到节能降耗、提高装置经济性的目的。优化后的流程压缩机比功耗最小为7.692k W·h/kmol,比未优化前的比功耗11.75k W·h/kmol少了4.0585k W·h/kmol。模拟结果对实际的天然气液化流程的优化具有有力的理论指导意义和可靠的实用参考价值。
[Abstract]:In recent years, under the pressure of controlling haze and reducing pollution, the rising demand for environmental control has pushed energy to clean up. With the development and utilization of low-carbon resources, the energy consumption structure of China has been further optimized, the proportion of coal in the primary energy consumption structure has decreased, the proportion of high-quality, clean and efficient natural gas consumption has increased. And the consumption is increasing day by day. This paper describes the present situation and development trend of natural gas liquefaction technology, briefly introduces the advantages and disadvantages of several natural gas liquefaction processes, and makes a technical and economic comparison. Priority is given to a new type of high efficiency process with propane precooled refrigerant cycle liquefaction, which is the most widely used at home and abroad. According to the thermal properties of natural gas and mixed refrigerants, PR equation and LKP equation are used for phase equilibrium and enthalpy entropy. By using Aspen HYSYS software, the comparison between the results obtained and the known experimental data is within the error range, which shows that the thermodynamic equation selected in the simulation process is appropriate. The modularization idea is used to simulate every device in the process. The flow chart is built with Aspen HYSYS software, and the parameters of compressor, multi-stream heat exchanger, throttle valve and mixer are set up in detail, and the convergent steady-state simulation system is obtained. The effects of mixture refrigerant composition, high and low pressure, temperature, raw gas pressure, temperature and propane precooling temperature on the process were simulated under steady flow conditions. The optimum mixture ratio of refrigerant is 0.436 (mole fraction), ethane is 0.393, propane is 0.099, nitrogen is 0.072. On this basis, the effective analysis of the key equipment of the process is carried out, and the process is further optimized to achieve the purpose of saving energy and reducing consumption, and improving the economic efficiency of the device. The optimized flow compressor has a minimum specific power consumption of 7.692kh / kmol. which is 4.0585khr / kmolless than that before the optimization of 11.75kW h/kmol. The simulation results are of great theoretical significance and reliable reference value for the optimization of natural gas liquefaction process.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE646

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