碳源对电转气工艺设计影响研究

Effect of Carbon Source on the Process Design of Power to Gas Technology

电转气工艺技术可将富余可再生能源电能转化成可大量长期储存的合成天然气。制备合成天然气,除了需要水电解提供的氢气,还需要合适的碳源,研究碳源对电转气工艺设计和优化的影响非常关键。借助Aspen Plus软件,首先考察了采用不同碳源时,单级流化床反应器达到工艺指标所对应的操作参数。模拟结果表明:生物沼气作为碳源时,采用低压单级流化床反应器即可达到工艺指标;采用气化气或纯CO_(2)作为碳源时,需要中高压才能实现工艺指标。为了优化工艺、降低成本,提出了一种两级流化床甲烷化工艺,采用分级进料和级间冷凝除水的方式,实现低压条件下保证合成天然气品质。

Power to gas technology can convert a large amount of surplus renewable energy into storable synthetic natural gas.In addition to hydrogen from water electrolysis,suitable carbon sources are also required.In this study,methanation with different carbon sources in a single-stage fluidized bed reactor was investigated with the Aspen Plus engineering software.The simulation results showed that,the standard of the gas product was achieved at low pressure when biogas was chosen as the carbon source.While syngas from biomass gasification or pure CO2 was used as the carbon source,much higher pressures were needed for products with high quality.To optimize the process and reduce costs,a two-stage fluidized bed methanation process was proposed here,where staged feeding and water removal between the two reactors were applied,so the quality of synthetic natural gas was ensured at low pressures.