基于化学链循环的天然气-太阳能互补转化具有低碳、储能及高效等特点。目前甲烷化学链循环典型还原温度为800℃。在450℃中温条件下,现有技术的甲烷转化率均较低,导致热化学蓄能效率和分布式能源系统能效较低。基于产物分离促进反应平衡移动原理,提出将甲烷重整制氢与化学链循环结合的蓄能方法,氢气被载氧体消耗使氢气分压降低,促进甲烷重整反应正向进行,进而提升甲烷转化率。对比了甲烷重整耦合化学链循环蓄能方法和传统甲烷直接与载氧体发生化学链反应蓄能方法的甲烷转化率。结果表明,450℃下通过多级循环实现甲烷近完全转化。基于甲烷重整耦合化学链循环蓄能方法,建立了多能互补分布式供能系统模型,太阳能甲烷热化学源头蓄能将低品位太阳能提升为高品位燃料化学能,实现了源头蓄能与脱碳。储存太阳能的固体燃料氧化产生高温热能,通过透平做功发电,然后通过余热回收装置实现吸收式制冷和供热,从而实现太阳能和化石燃料的高效互补利用。对系统在典型工况下的热力学性能进行分析,结果表明基于甲烷重整耦合化学链循环蓄能方法的分布式供能系统太阳能净发电效率达24.90%,系统燃料节省率达43.24%,在节能减排方面具有显著优势。

Complementation between natural gas and solar energy based on chemical looping exhibit advantages in low carbon emissions,energy storage, and high energy efficiency. Currently, typical reduction temperature of methane - based chemical looping is 800 ℃ .The conversion rate of methane is comparatively low at a medium temperature of 450 ℃ , resulting in reduced efficiency in both thermochemical energy storage and distributed energy systems. A novel thermochemical energy storage method was proposed to address thelow methane conversion rate under medium temperature conditions. The method involves the consumption of hydrogen by an oxygen carrier, leading to a decrease in hydrogen partial pressure, thereby shifting the reaction of methane reforming forward and subsequently enhancing methane conversion rates. Mechanistic experimental results show that the new thermochemical energy storage method of methane reforming coupled with chemical looping achieves a higher conversion rate than that of the traditional methane-based chemical looping. Methane is completely converted through multiple cycles at 450 ℃ . A multi-energy complementary distributed energy system model was established based on the new thermochemical energy storage method. Natural gas - solar thermochemical energy storage method elevateslow-grade solar energy to high-grade chemical energy while simultaneously achieving low-energy decarbonization. The solid fuel generatedfrom the natural gas-medium-temperature solar energy thermochemical method produces high-temperature thermal energy during the oxidation step. The high-temperature thermal energy is harnessed to generate electricity through a turbine, and subsequently, an excess heatrecovery system enables absorption refrigeration and heating, thereby achieving efficient complementary utilization of solar energy and fossilfuels. The operational performance of the system under typical conditions was investigated, showing that the distributed energy systembased on the new method achieved a net solar electricity generation efficiency of 24.90% and a fuel saving rate of 43.24%, demonstratingsignificant advantages in energy savings and emission reduction.

0 引言

1 试验

   1.1 甲烷化学链蓄能试验

   1.2 天然气-中温太阳能互补分布式系统

   1.3 参比系统

2 评估标准

3 结果讨论与分析

   3.1 中温甲烷化学链循环蓄能

   3.2 系统热力学性能分析

3 结论