LNG接收站输气负荷波动与冷能空分系统适配性研究

发布时间：2018-03-29 19:11

本文选题：液化天然气　切入点：冷能　出处：《华南理工大学》2015年硕士论文

【摘要】：随着我国能源供需矛盾日益紧张,LNG进口量逐年增大,合理利用LNG冷能显得愈加重要。然而,目前我国的LNG冷能利用项目中仍存在着一些技术症结阻碍产业发展。LNG接收站输气负荷会由于下游用户的用气波动而频繁变化,夜间用气低谷时LNG的气化量很少,甚至停止气化,致使LNG冷能利用装置冷量中断而不能连续稳定运行。本文以LNG冷能空分装置为研究对象,探寻LNG接收站输气负荷波动与冷能空分系统的适配性方案。本研究可解决LNG输气负荷与空分装置冷能需求在时间上不同步问题,为LNG冷能空分装置的连续稳定运行提供指导,同时可为国内其它冷能利用项目的建设提供有力的理论依据和技术支撑,促进我国LNG冷能利用产业发展。应用Aspen Plus化工流程模拟软件,建立LNG冷能空分工艺模型,首先对冷能空分装置的冷能需求、火用效率、多工况运行特点进行研究,然后探寻LNG输气负荷与冷能空分装置的适配性方案。LNG冷能空分装置正常工况下需要55.3t/h的LNG提供气化冷量,该流程液体产品单位能耗为0.41k Wh/m3,相比于传统流程约1.00k Wh/m3的单位能耗降低了约60%,节能优势明显。LNG冷能空分装置总体火用效率为38.1%,其中制冷系统火用损失最大,但与传统空分制冷系统相比有大幅度降低。当LNG冷能在一定范围内波动时,可以采用降低空分装置负荷率、改变产品分布等操作方式应对。而当LNG冷能供应出现中断时,针对冷能空分装置因此频繁停车的问题,提出了基于外置冷箱液氮冷媒回流供冷的方案,维持冷能空分装置连续运行。通过计算,LNG冷能供应中断时,采取该适配性方案需要消耗14.62t/h的储罐液氮,且该方案下的单位能耗为0.63k Wh/m3,相比于冷能供应正常工况下约0.41k Wh/m3的单位能耗有所升高。此外,对该方案进行经济效益分析可知,若LNG冷能供应中断时间在12个小时以内,采取液氮冷媒回流供冷方案更加合适,相较于直接停车收益情况有明显改善。
[Abstract]:With the increasing shortage of energy supply and demand in China, the rational utilization of LNG cold energy is becoming more and more important. At present, there are still some technical sticking points in the cold energy utilization project of LNG in China. The gas transmission load of the LNG receiving station will change frequently because of the fluctuation of the gas consumption of the downstream users, and the gasification capacity of the LNG will be little or even stopped at the low point of the night gas consumption. As a result, the cold energy of LNG is interrupted by the cooling rate of the device and can not run continuously and stably. In this paper, the cold energy air separation unit of LNG is taken as the research object. In order to find out the suitable scheme of gas load fluctuation and cold energy air separation system of LNG receiving station, this study can solve the problem that LNG gas transmission load and cold energy demand of air separation unit are out of sync in time, and provide guidance for the continuous and stable operation of LNG cold energy air separation unit. At the same time, it can provide strong theoretical basis and technical support for the construction of other cold energy utilization projects in China, and promote the development of LNG cold energy utilization industry in China. Using Aspen Plus chemical process simulation software, the LNG cold energy air separation process model is established. First of all, the cold energy demand, exergy efficiency and multi-condition operation characteristics of the cold energy air separation unit are studied. Then the suitable scheme of LNG gas transmission load and cold energy air separation unit is explored. Under normal condition, the LNG of 55.3t/h is needed to provide gasification cooling capacity. The unit energy consumption of liquid product in this process is 0.41k / m3. Compared with the traditional process, the unit energy consumption of 1.00k Wh/m3 is reduced by about 60. The energy saving advantage is obvious. The overall exergy efficiency of the cold energy air separation unit is 38.1, among which the exergy loss of the refrigeration system is the biggest. When the cooling energy of LNG fluctuates within a certain range, it can be handled by reducing the load rate of the air separation unit and changing the product distribution. When the cold energy supply of LNG is interrupted, In order to solve the problem of frequent shutdown of cold energy air separation unit, a scheme of reflux cooling with liquid nitrogen refrigerant is proposed to maintain the continuous operation of cold energy air separation unit. When the cold energy supply of LNG is interrupted, It needs to consume liquid nitrogen with 14.62t/h, and the unit energy consumption of this scheme is 0.63 k / m ~ (3), which is higher than that of 0.41 k / m ~ (3) when the cold energy supply is normal. In addition, the economic benefits of this scheme are analyzed. If the cold energy supply of LNG is interrupted for less than 12 hours, it is more appropriate to adopt the liquid nitrogen refrigerant reflux cooling scheme, which is better than the direct parking profit.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ116.11

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