【作者】 边海军；

【导师】 钱宇；

【作者基本信息】 华南理工大学 ， 化学工程， 2011， 博士

【摘要】 能源、环境问题已经日益成为制约我国经济可持续发展的一个瓶颈,为了优化能源结构,我国开始大力发展液化天然气(LNG)产业。由于LNG在气化时会释放出大量的冷能,因此,充分高效地利用LNG的冷能,有利于节约能源,创造巨大的经济效益。针对现有的LNG冷能发电技术发电量较小,能量利用效率较低等问题,本文考察了LNG直接膨胀工艺理论上的最大发电量、发电效率和火用效率。同时,通过对比五种LNG冷能的朗肯循环发电系统的混合工质。结果表明,在最小传热温差下,混合工质的复合冷凝曲线与LNG的气化曲线基本一致时,该系统的火用损失最小,其火用效率最高。针对我国众多的商品天然气含有大量的乙烷组分,本文设计了LNG冷能用于商品气轻烃回收工艺,该工艺具有较高的乙烷的回收率,与电压缩制冷工艺相比,该工艺的节电效益较好,具有较高的实际应用价值。同时采用火用分析法和图像火用分析方法(EUD),对该工艺的用能情况进行了分析,指出了该工艺的用能薄弱环节,为该工艺的优化奠定了理论基础。针对我国油田伴生气凝液回收工艺大多采用冷凝分离方法,其能耗较高,因此,本文提出了LNG冷能用于油田伴生气凝液回收工艺,该工艺可回收液态乙烷、LPG和轻油,凝液回收率高达96.8%;该工艺火用分析与图像火用分析的结果表明,与电压缩制冷工艺相比,本工艺的节电效率为65%的火用利用率为44.3%。技术经济分析结果表明,150×104Nm3/d的油田伴生气凝液回收工艺的投资回收期为2.25年,内部收益率为93.3%,本工艺具有较好的经济效益。目前的LNG冷能用于冷库技术不适用于LNG卫星站、不具备调峰功能。本文以丁烷为冷媒,开发了具有暂储冷特征和调峰功能的LNG冷能用于冷库工艺;采用火用分析法和图像火用分析方法(EUD),对该工艺进行了分析;结果表明,相对于电压缩制冷工艺,其节电效率为96%,火用效率为27.3%;技术经济分析结果表明,LNG冷能用于冷库工艺具有较好的经济效益。针对现有的废旧橡胶低温粉碎工艺能耗较高,自动化程度较低等问题,本文提出了以LNG冷能为冷源,空气为制冷介质,采用自控程度较高的流化床为关键设备的LNG冷能废旧橡胶低温粉碎工艺。研究结果表明,该工艺的能耗较低,每kg的废旧橡胶仅需耗电0.1kWh,相对于空气涡轮膨胀法可节电0.21 kW/kg(胶粉),节电效益约为67.7%。结合某接收站和卫星气化站的实际情况,本文分别提出了适用于某一LNG接收站和卫星气化站的LNG冷能集成利用工业实施方案,并对其分别进行了技术经济评价。研究结果表明,本文开发的LNG冷能集成利用工业实施方案即适用于某接收站和卫星气化站的实际情况,具有较高的LNG冷能利用率,同时,又具有较高的经济效益。在上述研究结果的基础上,按照“温度对口,梯级利用”的原则,本文将LNG冷能的高效集成利用与实际的工业环境有机结合,开发出了LNG冷能利用工艺软件。该软件可根据冷能用户的用冷需求和实际的工业环境,对各冷能用户的用冷需求自动进行匹配,并可对匹配结果进行简要的分析。更多还原

【Abstract】 To overcome the problem of energy supply security and environment protect, China will import a lot of liquefied natural gas (LNG) from other countries. LNG is a cryogenic liquid, and it should be vaporized before supplied to the final consumers. During the vaporized process of LNG, it releases a great deal of cryogenic energy. Using the cryogenic energy of LNG, it could not only save a lot of electric power but also decrease the environmental impacts of LNG vaporization.Since the existing power generation processes with LNG cryogenic energy has small power generating capacity and low energy efficiencies, a direct expansion power generation process with LNG cryogenic is proposed. And its theoretical maximum capacity, power efficiency and exergy efficiency were carried out in this paper. At the same time, five mixtures are compared in the Rankine cycle power generation system. The results show that the system has minimal exergy loss and the high exergy efficiency, when the complex mixture condensation curves are basically the same as LNG gasification curves.Ethane is one of main components of the commercial natural gas in China. As ethane has a higher value than methane, ethane should be recovered from the commercial natural gas. The ethane recovery process from the commercial natural gas with LNG cryogenic energy utilization is proposed. The proposed process has high ethane recovery efficiency. Compared to the power compression refrigeration process, the proposed process can save a lot of electricity. The process was analyzed by the method of exergy analysis and the energy utilization diagram (EUD). The results can be used in the optimization of the process.The current electric refrigeration recovery process of natural gas liquids has high energy consume. A novel process to recovery natural gas liquids from oil field associated gas with LNG cryogenic energy utilization is proposed. The proposed process recovers ethane, liquid petroleum gas (propane and butane) and heavier hydrocarbons, with total recovery rate of natural gas liquids up to 96.8%. Compared to the current electric refrigeration process, the proposed process uses the cryogenic energy of LNG and saves 62.6% of electricity. In this paper, exergy analysis and the energy utilization diagram method (EUD) are used to assess the new process. The results show that exergy efficiency of the new process is 44.3%. Technical and economic analysis showed that, the investment recovery period is 2.25 years, and its internal rate of return is 93.3%, which its capacity is 150×104Nm3/d oil field associated gas.The current process of cold storage with LNG cryogenic energy does not have peaking function, and does not apply to the LNG satellite station. In this paper, a novel process of cold storage with LNG cryogenic energy utilization is proposed, which butane is selected as the refrigerant. Exergy analysis and the energy utilization diagram method (EUD) are used to assess the new process. The results show that the proposed process can saves 96% of electricity, and its exergy efficiency is 27.3%. Technical and economic analysis show shat the new process has a promising economic benefit.Since the current cryogenic grinding processes of waste rubber have high energy consumption, a novel cryogenic grinding process of waste rubber with LNG cryogenic energy utilization is proposed, which air is selected as the refrigerant. The results show that the new process has lower energy consumption, and it consumed 0.1 kWh electricity per kg waste rubber. Compared to the air turbine expansion process, the process can save 67.7% of electricity.According to the actual industrial environment of some LNG receive terminal and LNG satellite station, the integrated utilization programs of their LNG cryogenic energy were dividedly proposed. Their technical and economic analysis was carried out, and the results showed that these two programs have high efficiencies of cryogenic energy, and have a promising future.Based on these results, the software of LNG cryogenic energy utilization is developed in this paper. The software can automatically calculate out the cryogenic energy needs of every customer, and match the needs of every customer. Then, the software can simply analyze the results.更多还原