| 摘要: |
| 液化天然气(LNG)因单位热值二氧化碳排放量低、能量密度高、清洁等优点，成为世界能源市场上增速最快的化石燃料。利用液化系统对LNG储运过程产生的闪蒸气（BOG）进行液化回收，不仅有显著的经济效益，同时可以满足环保要求。基于LNG运输过程中BOG再液化需求，本文设计了带冷量回收的新型混合工质再液化系统，同时建立了4种常规BOG液化系统模型，利用Aspen Hysys软件分析了典型工况下各系统的工作原理及内部能量传递关系，并对比了不同工况下各系统性能。结果表明，在所设进出口条件下：当BOG组分为纯甲烷时，混合工质液化系统比功耗及所需冷却水量明显低于氮膨胀液化系统，新型混合工质液化系统比功耗最低为0.53 kWh·kg-1；BOG流量每增加100 kg·h-1，氮膨胀液化系统功耗增加约100.05 kW，而带冷量回收的液化系统功耗仅增加63.60 kW。当BOG组分中氮气含量增加时，液化率降低，所需的制冷量、冷却水量均降低；当氮气含量约为5%时存在最小比功耗，此时氮膨胀系统比功耗最小为0.96 kWh·kg-1，带冷量回收的混合工质液化系统比功耗最低为0.51 kWh·kg-1。带冷量回收的新型混合工质再液化系统结构紧凑、能耗更低，是应用于LNG船舶BOG再液化工艺的优选方案之一。 |
| 关键词: LNG BOG 冷量回收 氮膨胀液化系统 混合工质液化系统 比功耗 |
| DOI： |
| 投稿时间：2023-03-24修订日期：2023-05-18 |
| 基金项目:上海市青年科技英才扬帆计划（批准号：21YF1451400），中国船舶集团自立科技研发专项（批准号：202204Z） |
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| Design and analysis of new marine BOG re-liquefaction system |
|
DING Zhi1, YANG Zhiqiang1, XIA Menghan2, WANG Chang1, LIU Yu1
|
| (1.Shanghai Marine Diesel Engine Research Institute;2.Shanghai Micropowers. Ltd.) |
| Abstract: |
| Liquefied natural gas (LNG) is the fastest growing fossil fuel in the world energy market due to its low carbon dioxide emissions, high energy density and cleanliness. Using the liquefaction system to efficiently deal with the flash vapor (BOG) generated during LNG transportation can not only reduce the natural gas loss, but also meet the environmental requirements. Based on the requirements of BOG reliquefaction during LNG transportation, this paper designed a new mixed refrigerant reliquefaction system with cooling recovery, and established four conventional BOG liquefaction systems. The working principle and internal energy transfer relationship of each system were analyzed by using chemical process simulation software, and the performance of each system under different working conditions was compared. The results show that when the BOG is pure methane, the specific power consumption and cooling water required by the liquefaction system of mixed working medium are significantly lower than the nitrogen expander liquefaction system, and the minimum specific power consumption of the new system is 0.53 kWh·kg-1. When the BOG flow increases by 100 kg·h-1, the power consumption of the nitrogen expander liquefaction system increases by about 100.05kW, while the power consumption of the liquefaction system with cold recovery only increases by 63.60kW. When the nitrogen content in BOG increases, the cooling capacity, cooling water and liquefaction rate all decrease. When the nitrogen content is about 5%, the minimum specific power consumption exists. In this case, the minimum specific power consumption of the nitrogen expansion system is 0.96 kWh·kg-1, and the minimum specific power consumption of the mixed working medium liquefaction system with cooling capacity recovery is 0.51 kWh·kg-1. The new reliquefaction system of mixed refrigerant with cooling recovery has compact structure and lower energy consumption, which is an alternative scheme for LNG ship BOG reliquefaction process. |
| Key words: LNG BOG cold recovery expander liquefaction system mixed refrigerant liquefaction system specific power consumption |