LNG冷能发电制氢及液化的综合能源系统研究

Research on integrated energy system for hydrogen production and liquefaction from LNG cold energy generation

目的为实现LNG冷能的回收利用、氢气的绿色制取和液态储运的多重目标,提出LNG冷能发电作为电解水制氢的电力来源,同时提供氢液化用能,并辅助氢预冷的一套综合能源系统。方法使用HYSYS软件对LNG冷能发电循环及氢液化进行模拟测算,建立系统中各单元物料与电能匹配关系的数学模型,通过模型求解获得了直接膨胀、朗肯循环、联合循环3种发电方式在不同外输压力下的年液氢产量。结果LNG年接收量为300×10^(4)t时,综合能源系统液氢产量约1420~3790 t/a。结论在相同外输压力下,制氢效率相同时的联合循环发电制氢效益最明显;其他条件相同时,随外输压力的增大,制氢量呈下降趋势;同等条件下,PEM电解制氢效益优于碱性电解法。

Objective In order to achieve the multiple objectives of LNG cold energy recycling,green hydrogen production and liquid hydrogen storage and transportation,an integrated energy system which utilizes LNG cold energy to power generation as a power source for hydrogen production from electrolytic water and hydrogen liquefaction,and meanwhile LNG roles as hydrogen liquefaction pre-refrigerant is proposed.Methods The process of LNG cold energy power generation and hydrogen liquefaction by HYSYS is simulated and calculated.A mathematical model of the relationship between materials in each unit and the distribution of electric energy is established.The annual liquefied hydrogen production are obtained for three power generation modes of direct expansion,Rankine cycle and combined cycle under different export pressures by solving the model.Result When the annual LNG receiving capacity is 3 million tons,the liquid hydrogen output of the integrated energy system is about 1420-3790 tons per year.Conclusions It is found that under the same export pressure and efficiency,the hydrogen production benefit of combined cycle power generation is mostly obvious.When other conditions are same,the hydrogen production decreases with the increase of export pressure,and the benefit of PEM electrolysis is better than that of alkaline electrolysis.