LNG加气站BOG再液化工艺研究及经济性分析

Study and economic analysis on BOG re-liquefaction process at LNG filling station

关键词:  LNG加气站  BOG  液氮冷量  再液化  经济性分析  零排放 

Key words:  LNG filling station  BOG  liquid nitrogen cooling capacity  re-liquefaction  economic analysis  zero emission

摘要:

蒸发气(Boil-Off Gas,BOG)的处理是LNG加气站应考虑的关键问题之一,关系着加气站的能耗及安全平稳运行。为此,建立了LNG加气站BOG产生量静态计算模型,以兰州市某加气能力为1.5×10⁴ m³/d的加气站为研究对象,设计提出了1套利用液氮冷量的BOG再液化装置(1台液氮储罐,1台BOG/液氮换热器,1台LNG收集罐及管路阀门),以避免BOG直接放散造成的能源浪费和环境污染,实现加气站BOG“零排放”。在此基础上,理论计算了BOG再液化装置的再液化能力,并对其进行经济效益分析。结果 表明,加气站BOG的产生量为322 kg/d,BOG再液化量与液氮消耗量质量比为1∶1.92,为试验装置的设计提供了理论依据。该装置安全寿命期内静态分析总投资费用为39万元,税前年利润总额为14.4万元,净利润为10.5万元,经济效益较为显著。由此可知,LNG加气站应考虑BOG再液化装置投资。 

Abstract:

The BOG(Boil-Off Gas)process related to energy consumption and safe operation is one of the critical issues that should be considered at LNG filling station. Therefore, the model of BOG static calculation is established, taking the 1.5×10⁴ m³/d capacity of LNG filling station in Lanzhou as an example, a set of BOG re-liquefaction equipment(mainly including one liquid nitrogen tank, one BOG/liquid nitrogen exchanger, one LNG collection tank, a few pipeline and valve)which uses liquid nitrogen cooling capacity is designed to avoid energy dissipation and environmental pollution caused by BOG direct discharge. BOG re-liquefaction capacity of the equipment is theoretically calculated and its economical benefit is analyzed. The results show that the amount of BOG production is 322 kg/d, the mass ratio of BOG re-liquefaction capacity and liquid nitrogen consumption is 1∶1.92, which provides the theoretical basis for the design of the test equipment. The total cost of static analysis of the BOG re-liquefaction equipment is 0.39 million yuan, the total profit before tax is 0.144 million yuan, and the net profit is 0.105 million yuan. Therefore, it has good economical benefit. Accordingly, the investment should be considered to BOG re-liquefaction equipment of LNG filling station.