氢气是未来国家能源体系的重要组成部分,是用能终端实现绿色低碳转型的重要载体。绿色经济的氢气规模化供给是未来能源体系发展的迫切需要。煤炭地下气化技术可将地下煤炭原位高效转化为富氢气体,并将产生的二氧化碳回注气化空腔进行地质封存,有望成为一种煤炭低成本供氢路径。重点解析了煤炭地下气化过程富氢气体的析出机制,总结了典型煤炭地下气化制氢工程案例,对比了不同制氢技术路线的氢气成本,深化了耦合CCUS的深部煤炭地下气化制氢路径。研究结果表明,煤炭地下气化过程富氢气体的析出包括煤层内的热解析氢、高温区的还原析氢以及低温气流通道中的水煤气变换。煤层内的中低温热解区范围较大,主要产生富氢气体H2与CH4,是产品气的重要组成部分;煤层富水特征和H2O(g)高气化活性使水蒸气还原制氢反应成为主导反应,低温长气流通道及气化灰渣的催化作用为原位水煤气变换制氢创造了条件。国内外典型示范项目运行数据验证了煤炭地下气化具有生产富氢气体的天然优势,其制氢成本远低于地面煤制氢和天然气制氢。气化空腔回注二氧化碳具有矿化固碳及物理碳封存的双重优势,深部煤炭地下气化制氢耦合气化空腔储碳,并联产化学品或协同深部驱油/驱替煤层气,有望形成二氧化碳近零排放的规模化低成本制氢技术路径。深部煤炭地下气化制氢耦合CCUS技术,对发挥新型能源体系支柱作用,解决化石能源制氢碳排放难题具有重要意义,是符合中国国情的化石能源清洁转型发展路径。

Hydrogen is a key component of the future national energy system and an important carrier for achieving green low-carbon trans⁃formation in energy end-use sectors. The large-scale supply of green and low-cost hydrogen is an urgent need for the future developmentof the energy system. Underground coal gasification (UCG) technology efficiently can convert in-situ coal into hydrogen-rich combustiblegas, and store CO2 during gasification into gasification cavity, which is expected to be an ideal low-cost hydrogen supply path. The gener⁃ation mechanism of hydrogen-rich gas during UCG was focused on, typical engineering cases of hydrogen production via UCG was sum⁃mariztd and cost of different hydrogen production technologies and deepens the deep UCG coupled with carbon capture, utilization, andstorage (CCUS) hydrogen production pathway were compared. The research results indicate that, the direct sources of hydrogen-rich gasin the UCG process include coal pyrolysis reaction, steam-reducing reaction, and water-gas shift reaction in the gas flow channel at lowertemperature. The medium-to-low temperature pyrolysis zone in the coal seam is a significant part of the product gas, which mainly pro⁃duces hydrogen-rich gas H2 and CH4. The rich water characteristics of the coal seam and the high gasification activity of H2O (g) makethe reduction zone dominated by the steam decomposition reaction. Moreover, the long gas flow channel at lower temperature and catalyticeffect of gasification slag further promote water-gas shift reaction. Operating data from typical demonstration projects at home and abroadhave verified that UCG has a natural advantage in producing hydrogen-rich gas, and its hydrogen production cost is much lower than thatof surface coal gasification and natural gas. Injecting carbon dioxide back into the gasified cavity has the dual advantages of mineral car⁃bonation and physical carbon storage. Coupling CCUS technology with deep UCG for hydrogen production and simultaneously producingchemicals or jointly driving deep oil/ gas recovery can form a low-cost hydrogen production path with near-zero carbon emissions of carbondioxide. The coupling of CCUS technology with deep UCG for hydrogen production has important significance for exerting the pillar role ofa new energy system, solving the carbon emission problem of fossil energy hydrogen production, and it is a road to clean transformationand development of fossil energy with Chinese characteristics that conforms to the national conditions of China.

0 引言

1 煤炭地下气化富氢气体的生成途径

   1.1 热解析氢过程

   1.2 还原析氢过程

   1.3 气化通道低温区的水煤气变换反应

2 煤炭地下气化工程产氢数据分析

3 不同制氢路径成本对比分析

4 耦合CCUS技术的深部煤炭地下气化制氢路径

5 结语