【作者】 李素燕；

【导师】 陈安斌；

【作者基本信息】 哈尔滨工业大学 ， 制冷及低温工程， 2006， 硕士

【摘要】 液化天然气(LNG)在天然气的储存和运输方面都具有十分明显的优势,而我国的天然气液化技术是一项新兴的技术,正在迅猛发展,但与国外天然气液化技术相比,国内天然气液化技术起步较晚,差距很大。尤其是我国存在许多零散的天然气资源,由于各种条件的限制,这些资源没有得到开发或利用,小型液化天然气装置研制的目的正是为了开发和利用边远地区零散天然气资源,使这些无法开发利用的天然气资源优势真正转化为经济优势。本文从热力学角度出发,对小型氮气膨胀天然气液化流程模拟与优化进行了详细的研究。本文首先论述了国内外天然气液化技术的现状和发展趋势,阐述了液化技术原理,并通过各地天然气液化工厂的不同液化技术的比较,给出了液化流程的选择原则;确定了以P-R方程作为计算天然气液化相平衡的基础模型,并对液化流程中的设备(压缩机、膨胀机和节流阀、多股流换热器)建立了数学模型;结合气源特点,拟选出三套小型氮膨胀天然气液化流程,并在前两步的基础上,进行了全流程的模拟和分析,最终确定采用丙烷预冷的单级氮气膨胀天然气液化流程。本文对丙烷预冷的单级氮气膨胀天然气液化流程进行了热力学分析,重点分析天然气的压力、天然气的温度、天然气中甲烷含量、增压透平膨胀机入口压力、入口温度、出口压力、储存压力对流程参数的影响;并在此基础上以比功耗为目标函数,对流程参数进行了优化。本文还对氮气膨胀天然气液化流程中的重要设备增压透平膨胀机进行了设计计算及其通流部分的结构设计,得出了各部分的热力参数及结构尺寸,并针对导流器设计不成熟的原因,在此基础上对导流器进行了数值模拟,得出了其压力、温度及速度的分布。由此可见膨胀机的设计还是比较成功的。更多还原

【Abstract】 Liquid natural gas (LNG) has obvious advantages in storing and transporting natural gas. Compared to LNG technology in western nations, the LNG technology in China which is a new technology and developing rapidly have a shorter history and a big technology gap. There are lots of scattered and remote natural gas resources in China, which haven’t been utilized for limits of kinds of conditions, and our purpose of researching small plants of gas liquefaction is no other than to utilize these natural gas resources. Based on thermodynamics, here the simulation and optimization of the process of nitrogen expander cycle for small scale gas liquefaction plants have been researched.In this thesis first the history and trends of LNG technology in the world is presented, and the principle of liquefaction technology is introduced. Based on the investigation of different liquefaction technology chosen by plants of natural gas liquefaction over the world, the choosing principles for liquefaction process are presented here too. The author chooses the PR equation to calculate the phase equilibrium properties of LNG liquefaction, and builds mathematic models for equipment modules in the liquefaction cycle, which consists of compressor,multi-flow heat exchanger, expander and throttle valve. Considering the characteristics of natural gas resource, the author presents three flow process of nitrogen expander cycle for small scale gas liquefaction plants, simulates and analyses the whole process based on the two steps before. Finally, the author chooses the process of one-nitrogen expander cycle with propane precooling.In this thesis the thermodynamic analyze of one-nitrogen expander cycle with propane precooling has been discussed. The author especially analyses the influence on process parameters from the factors including: the pressure, temperature and methane fraction of natural gas, the inlet-temperature, outlet-pressure, storing pressure and the inlet-pressure of boosted turbine expander. The author optimizes the process, using the minimum power consumption of the compressor as the aim function.In this thesis, the design calculation and the structural design of pass part of the boosted turbine expander which is important equipment in the liquefaction process更多还原