Song Guohui, Wang Liang, Yao Ailin, Cui Xiaobo, Xiao Jun
School of Energy and Power Engineering, Nanjing Institute of Technology, Nanjing, Jiangsu 211167, China.
Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, Jiangsu 210096, China.
ACS Omega. 2021 Oct 11;6(42):27851-27864. doi: 10.1021/acsomega.1c03489. eCollection 2021 Oct 26.
Natural gas shortage, waste treatment, and renewable energy utilization and storage are the common issues in China. This research aims to evaluate a simple and reliable biomass and power-to-syngas process for high-quality syngas production integrating oxygen gasification and water electrolysis. The technical and economic evaluations are successively performed based on the simulation data. The single-stage and two-stage gasifiers are integrated and compared. The results show that the process with a two-stage gasifier has advantages in both technical and cost performances over that with a single-stage gasifier. Then, the optimal values of the operating variables are determined by investigating their effects on syngas composition and yield and the overall energy and exergy efficiencies. Then, by setting appropriate amounts of water for electrolysis and methanation pressures, the process can generate two typical products: thermochemical synthetic biogas (TSB) or synthetic natural gas (SNG). The overall energy and exergy efficiencies of TSB can reach 74.1 and 69.5%, respectively, while those of SNG can achieve 64.8 and 64.1%, respectively. The unit product cost of TSB is about one third of that of SNG, indicating that TSB makes a profit while SNG results in loss. A sensitivity analysis of the cost indicates that the constraints for TSB are much looser than those for SNG to gain profit. Additionally, this study proposes two indicators to characterize the electricity-storage capacities of biomass and syngas. The indicators show that SNG has big advantages over TSB in the specific capacity of electricity storage, and the capacities of SNG and TSB are approximately 52.0 and 4.7 times of the specific energy density of the lithium-ion battery pack in 2019, respectively. The work could be used as a reference for the countries lacking natural gas and valuable to guide the development of a two-stage gasifier, reduction in equipment cost, and evaluation of electricity-storage performance using biofuels.
天然气短缺、废物处理以及可再生能源的利用与存储是中国面临的常见问题。本研究旨在评估一种简单可靠的生物质与电制合成气工艺，用于整合氧气气化和水电解以生产高质量合成气。基于模拟数据相继进行技术和经济评估。对单级气化炉和两级气化炉进行整合与比较。结果表明，与单级气化炉相比，两级气化炉工艺在技术性能和成本性能方面均具有优势。然后，通过研究操作变量对合成气组成和产率以及整体能量和㶲效率的影响，确定操作变量的最佳值。接着，通过设定适当的电解水量和甲烷化压力，该工艺可生成两种典型产品：热化学合成生物气（TSB）或合成天然气（SNG）。TSB的整体能量和㶲效率分别可达74.1%和69.5%，而SNG的分别为64.8%和64.1%。TSB的单位产品成本约为SNG的三分之一，这表明TSB盈利而SNG亏损。成本敏感性分析表明，TSB盈利的限制条件比SNG宽松得多。此外，本研究提出了两个指标来表征生物质和合成气的蓄电能力。指标显示，SNG在蓄电比容量方面比TSB具有很大优势，SNG和TSB的蓄电容量分别约为2019年锂离子电池组比能量密度的52.0倍和4.7倍。该研究可为缺乏天然气的国家提供参考，对指导两级气化炉的开发、降低设备成本以及评估生物燃料的蓄电性能具有重要意义。
