影响煤生物气化的物化特征及煤预处理的研究进展

Physicochemical characteristics affecting biological coal gasification and coal pretreatment

摘要:

在“双碳”目标引领下，传统化石能源将逐渐被取代。我国煤炭资源储量多、分布广，将不可开采的煤炭资源生物气化可作为天然气资源的重要补充。因此，研究生物成因煤层气的增产机理具有重要的理论和现实意义。煤生物气化的发展前景广阔，但难点在其缓慢的动力学特征。为揭示生物煤层气的生成潜力和内部因素，本文就煤的物理化学特征对生物气化的影响、煤的物化性质对生物作用的响应以及预处理煤提高其生物有效利用性进行系统论述。生物作用降解煤的内部因素和环境条件已通过室内研究查明，发现低阶煤比高阶煤更具生物气增产潜力。产甲烷微生物群落对煤的生物转化过程势必引起煤的各项物理化学性质的变化。为产甲烷菌持续提供可用底物是煤生物气化的主要限制因素，研究多以化学预处理手段提高煤生物气化的效率和产量，而超临界CO₂萃取以物理方式溶解大分子网格中小分子有机物用于生物气化。生物成因煤层气的增产潜力巨大，但室内实验条件与储层环境差异明显，原位增产有待深入研究，煤层有机物生物转化的微生物学研究亦有待完善。不同煤阶、不同储层环境对生物气化影响的主控因素研究是实现煤的生物气化商业化开发的关键。

Abstract:

Under the goals of carbon peaking and carbon neutrality, traditional fossil energy will be gradually replaced. China’s coal resources feature huge reserves and wide distribution. The biological gasification of untapped coal resources can provide additional natural gas resources. Therefore, it is of great theoretical and practical significance to study the mechanism of biological coalbed methane stimulation. Biological coal gasification is promising, but the difficulty lies in its slow dynamic characteristics. To reveal the generation potential and internal factors of biological coalbed methane, we discussed the influence of physicochemical characteristics of coal on biological gasification, the response of coal physicochemical properties to biological action, and the improvement of coal utilization by pretreatment. The internal factors and environmental conditions of biodegradable coal had been identified through indoor research. It was found that low-rank coal had a higher potential for biological coalbed methane production than high-rank coal. The biotransformation of coal by methanogenic microorganisms is bound to cause changes in the physicochemical properties of coal. It is a challenge to continuously provide available substrates for methanogens, which thus limits the biological coal gasification. Chemical pretreatment of coal is mostly used to improve the efficiency and methane yield of biological gasification, while supercritical CO₂ extraction physically dissolves small molecular organics in a macromolecule network for gasification. The production of biological coalbed methane can be further increased, but the in-situ increase needs to be further studied in light of the obvious differences between indoor experimental conditions and reservoir environments. The microbiological research on the biotransformation of organic matter in coal seams should be improved. The study of the main factors controlling the influence of different coal ranks and different reservoir environments on biological gasification is the key to the commercialization of biological gasification.