文献推荐：以真实木材气化气为燃料的商用 SOFC 堆的原位电化学阻抗分析

DOI: https://doi.org/10.1016/j.heliyon.2024.e32509

原位链接：https://www.cell.com/heliyon/fulltext/S2405-8440(24)08540-2

固体氧化物燃料电池 (SOFC) 与木材气化相结合，有可能显著提高可再生电力产量并减少排放。根据木材气体的质量，降解过程对 SOFC 的可靠性和寿命有显著影响。本研究使用电化学阻抗谱 (EIS) 和弛豫时间分布 (DRT) 分析，确定了木材气化与商用 SOFC 堆耦合对性能衰减的影响。评估了 SOFC 堆在不同运行条件下的热行为，以及按氢碳比 (H/C) 分类的各种合成木材气体混合物。在合成气和真实木材气体运行过程中观察到的 H/C 比从 8 降至 1，导致Nyquist plots向右移动，表明 SOFC 堆的阻抗增加。使用 DRT 分析解释 EIS 结果，确定了 H/C 比变化与其对阳极电氧化、离子传导、气体传输和扩散的影响之间的相关性。通过加入上游脱硫系统并确保 H/C 比大于 2，生物质气化与 SOFC 堆的结合可以稳定地解决性能衰减问题。

Fig. 1 Schematic illustration of the experimental setup and current flows consisting of the SOFC-stack integrated into the Galileo 1000 N heating system. Additionally, it shows the FRA device responsible for regulating the current excitation (i_exc), the DC-DC converter controlling the external load (i_L), and the electronic load with its current (i_el).

Fig. 2 Tar concentration of the real wood gas produced by a lab-scale allothermal gasifier designed by our institute operating at 800 °C, pressure of 0.6 bar and with an outlet volumetric flow rate of 2 up to 4 l min⁻¹.

Fig. 3 Nyquist (A) and DRT (C) plots of the SOFC stack at open-circuit voltage (OCV) under standard conditions (820 °C and 2.5 l min⁻¹) using NG as fuel. These plots serve as example for the method used for the region identification from the Nyquist to the DRT plot. The high frequency region (f > 1 kHz) of the Nyquist plot is associated to region 1 (pink), the middle frequency region (1 kHz < f < 1 Hz) to region 2 (green), and the low frequency region (0.13 Hz < f < 1 Hz) to region 3 (orange). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article).

Fig. 4 Current-voltage characteristic curves of the SOFC stack under the experimental condition of test 1 (A) variation of the temperature under the constant pre-reformed NG flow of 2.5 l min−1 at 800 °C, 820 °C, 850 °C and test 2 (B) variation of the volumetric flow rate with 2.1 l min⁻¹, 2.5 l min⁻¹ and 2.9 l min⁻¹ at a constant temperature of 820 °C.

Fig. 5 Nyquist plots of the SOFC stack at OCV with a variation of (A) the temperature at 800 °C, 820 °C, 850 °C (tests 1a-c) under the constant pre-reformed NG flow of 2.5 l min⁻¹ and of (B) the volumetric flow rate of 2.1 l min⁻¹, 2.5 l min−1 and 2.9 l min⁻¹ under a constant temperature of 820 °C (tests 2a-c).

Fig. 6 DRT plots of the SOFC stack at OCV with a variation of (A) the temperature under the constant pre-reformed NG flow of 2.5 l min⁻¹ at 800 °C, 820 °C, 850 °C (tests 1a-c) (B) the volumetric flow rate of 2.1 l min⁻¹, 2.5 l min⁻¹ and 2.9 l min⁻¹ at a constant temperature of 820 °C (tests 2a-c).

Fig. 7 (A) Nyquist plot of the SOFC stack and (B) a zoomed view of the low impedance area of the same Nyquist plot (right) for real (orange curves) and synthetic wood gas (green curves). Also included as references are the hydrogen and pre-reformed NG curves (pink curves). Operating conditions: T = 820 °C and i_L = 10 mA cm⁻². (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article).

Fig. 8 DRT plot of the SOFC stack for real (orange curves) and synthetic wood gas (green curves). Also included as references are the hydrogen and pre-reformed NG curves (pink curves). Operating conditions: T = 820 °C and i_L = 10 mA cm⁻². (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article).