A study on methane–air premixed flames interacting with syngas–air premixed flames

Numerical study on the interaction between methane–air and syngas–air premixed flames is conducted according to equivalence ratio and global strain rate in detailed chemistry. This study targets at understanding of an interacting combustion system as an alternative retrofit concept where one can modify the existing facilities minimally in industrial and power plant burners in order to reduce the emission of carbon dioxide. It is seen that methane premixed flame interacting with syngas premixed flame can be sustained even over the rich flammable limit of single methane premixed flame. The inspection of detailed flame structure such as the distributions of major species and chain carrier radicals, flame separation distance, spatial flow velocity, and spatial distribution of the rate of production and consumption of CH₄, H₂, and CO is also conducted to depict the flame interactions. The importance of global strain rate and thus the flame separation distance in the enhanced burning of methane premixed flame is also stressed through the inspection of the consumption rates of H₂, CO, and CH₄. Anomalous phenomena such as the migration of premixed flame cross the stagnation plane and the nearly constant flame separation distance are also discussed.     

生物质化学链气化联合燃气轮机发电系统模拟

使用Aspen Plus软件对以Fe_2O_3为载氧体的生物质化学链气化系统进行模拟,分析温度、压力、载氧体与生物质摩尔比、水蒸气与生物质摩尔比等因素对合成气制备的影响;对不同生物质的气化条件进行优化;将气化制得的合成气通入M701F燃气轮机中发电,考察系统的发电效率。结果表明:常压下,不同生物质气化的优化温度均在740℃左右,此时制备的合成气冷煤气效率较高;提高反应压力有利于系统热量自平衡,但合成气的冷煤气效率降低;载氧体与生物质摩尔比的优化值与生物质中氧碳摩尔比呈负相关,且达到优化值时,气化环境中氧碳摩尔比在1.25左右;水蒸气通入气化系统后冷煤气效率可提高15.00%～20.00%,主要原因为H_2的产量显著增加,通入水蒸气后的气化环境的氧碳比在1.4左右时,制备合成气的冷煤气效率较高;系统的发电效率在30.00%～37.00%,高于生物质发电效率。     

Turbulent explosion characteristics of stoichiometric syngas

In the present article, series of experiments were conducted to investigate turbulent explosion characteristics of stoichiometric syngas (with different hydrogen concentrations, 10%‐90% in volume fraction) in a 28.73‐L spherical turbulent premixed explosion system. The evolution of explosion pressure was recorded in different turbulent environment (with different turbulent intensity, 0.100‐1.309 m/s in root mean square value of velocity fluctuation). From the explosion pressure historic curves, the maximum pressure, lag duration, and explosion duration were obtained; the pressure rise rate and fast burn duration were derived; and deflagration index could be further calculated. The interaction effects of turbulent intensity and hydrogen addition on those explosion parameters were systematically analysed and discussed. Based on the results, an empirical formula about deflagration index of stoichiometric syngas was established.     

Hydrogen-rich syngas fermentation for bioethanol production using Sacharomyces cerevisiea

Bioethanol is an eco-friendly biofuel due to its merit that makes it a top-tier fuel. The present study emphasized on bioethanol production from hydrogen-rich syngas through fermentation using Sacharomyces cerevisiea. Syngas fermentation was performed in a tar free fermenter using a syngas mixture of 13.05% H₂, 22.92% CO, 7.9% CO₂, and 1.13% CH₄, by volume. In the fermentation process, effects of various parameters including syngas impurity, temperature, pH, colony forming unit, total organic carbon and syngas composition were investigated. The yield of bioethanol was identified by Gas chromatography-Mass spectrometry analysis and further, it was confirmed by Nuclear magnetic resonance (¹H) analysis. From GC-MS results, it is revealed that the concentration of bioethanol using Saccharomyces cerevisiae was 30.56 mmol from 1 L of syngas. Thus, hydrogen-rich syngas is suited for bioethanol production through syngas fermentation using Saccharomyces cerevisiae. This research may contribute to affordable and environment-friendly bioethanol-based energy to decrease the dependency on fossil fuels.     

Response Surface Optimization of Hydrogen-Rich Syngas Production by Greenhouse Gases Reforming

The effect of process interaction and response surface optimization of hydrogen-rich syngas production by catalytic carbon dioxide (CO₂) reforming of methane (CH₄) was evaluated. The Box-Behnken design was applied to investigate the influence of CH₄ partial pressure, CO₂ partial pressure, and temperature on the hydrogen yield. The analysis of variance indicated that temperature and CH₄ partial pressure had the most significant impact on the hydrogen yield. Under optimum conditions a maximum hydrogen yield of 71.38 % was achieved. Model validation with the ideal conditions confirmed close agreement of the predicted hydrogen yields with experimental values.     

CFD modeling and performance comparison of solid oxide fuel cell and electrolysis cell fueled with syngas

Reversible solid oxide fuel cells (rSOFCs) may be applied to store and generate electrical energy in a reversible mode. This technique is promising to balance the conflict between intermittent power supply and demand in a sustainable way. One of the limitations of the development of rSOFCs is the high cost of storage and usage of pure H₂, which may be solved by employing syngas as the fuel. The performance of rSOFCs depends on the development of bifunctional materials, cell design, and operation optimization, which are often investigated and predicted by the cost‐effective approach of mathematical modeling. However, the modeling of dual‐mode rSOFCs involving co‐redox reactions with syngas is not well developed. In this study, a two‐dimensional (2D) single‐channel model of an rSOFC is developed. The novelty of this model is that the multiphysics transport processes are fully coupled and solved with the reversible water‐gas shift reaction with syngas and the electrochemical reactions. The effects of the operating conditions and design parameters (eg, electrode thickness) are considered, with the aim of providing guidelines to optimize the design and operation of reversible cells. It is concluded that the thickness of the electrode has a larger impact on the water‐gas shift reaction than on the electrochemical reaction in both the gas diffusion and reaction regions. The C/H element ratio of syngas has a negative correlation with power output, but the distributions of current and gas species may be improved in both modes. A higher operating temperature improves the performance in both modes but has a more substantial effect in the electrolysis mode. The specific design and operating schemes favored in different modes should be balanced in the reversible mode.     

热处理对K_2MoO_4-P_(0.2)/SiO_2催化剂结构及性能的影响

采用等体积浸渍法制备了K2MoO4-P0.2/SiO2催化剂,通过XRD,TG,H2-TPR,XPS方法对催化剂进行了表征,考察了焙烧气氛、焙烧温度对催化剂表面结构及其催化性能的影响。实验结果表明,空气中焙烧的催化剂由于添加剂柠檬酸在焙烧过程中发生燃烧反应,造成局部过热,导致催化剂表面活性物种部分烧结长大,从而降低了催化剂的活性;而在氮气中焙烧的催化剂,由于柠檬酸缓慢分解且形成了还原性气氛,将易还原的Mo-O物种还原,形成了更多的活性Mo物种,且活性组分分散更均匀,从而表现出了比空气中焙烧的催化剂更高的活性。对于甲硫醇合成反应,后者的CO转化率提高约10%,甲硫醇选择性提高约7%。     

合成气生物发酵法制乙醇的研究进展

采用合成气生物发酵法制乙醇具有反应条件温和、产物选择性高、原料来源广泛、低碳可持续发展等优势,是一种具有前景的可再生能源新型生产工艺。文章综述了合成气发酵法制乙醇的微生物种类及对应的适宜操作条件,分析了合成气发酵法制乙醇的Wood-Ljungdahl代谢途径;总结了合成气的广泛来源;分析讨论了过程工艺参数如合成气组成及压力、pH、温度、培养基组分、气液传质对合成气发酵的影响;指出合成气发酵法制乙醇面临的底物传质性能差、乙醇收率低等关键问题,比较了典型反应器在传质方面的差异,归纳了传质强化方法;总结了合成气发酵法制乙醇的工业化进展, 并提出了未来的发展方向。     

深度融合特征提取网络及其在化工过程软测量中的应用

复杂化工过程的观测数据往往同时包含非线性和强动态特性,而传统的化工过程软测量方法无法准确提取观测数据的非线性动态特征,以至影响数据建模和质量预报的准确性。提出了一种基于变分自编码器的深度融合特征提取网络(deep fusion features extraction network, DFFEN)。在变分自编码器框架下,通过构建潜隐特征信息传递通道,提取非线性动态潜隐变量。并利用自注意力机制(self-attention)融合关键的隐层信息,优化因信息传递通道过长而导致的潜在特征被遗忘的问题。此外,在后端网络构建潜隐变量和关键质量变量之间的回归模型,以实现关键质量变量的预报。最后,通过数值案例和实际的合成氨过程验证了所提出的DFFEN模型的可行性和有效性。     

基于ReaxFF-MD和DFT的废旧PP塑料水蒸气气化机理研究

气化技术是处理日益增多的废旧塑料并生产富H₂合成气的重要方法。利用ReaxFF-MD与DFT方法相结合研究了聚丙烯(PP)塑料水蒸气气化的反应机理及各产物气的生成路径,进一步探究了温度、水含量对合成气产物分布的影响。研究结果表明：PP塑料的水蒸气气化前期以解离能较小处的单体连接键断裂形成丙烯(CH₃—CH\stackrel{}{̿}CH₂)单体为主要反应过程。随后,单体继续解离生成更小的C₁~C₂烃类分子及·H、CH₃·等自由基片段。在水蒸气重整反应阶段,H₂的生成有多种路径,但由前期含C结构上脱掉的游离·H自由基与H₂O的结合是H₂的最主要生成路径,占据了H₂生成量的70%。同时伴随产生的·OH自由基通过与小分子结合,脱H等过程,是CO的主要生成方式。提高温度和含水量可促进烃类的水蒸气重整反应,从而提高H₂和CO合成气产率,但改善效果逐渐减弱。以上结果对于掌握塑料水蒸气反应进程,以及实验参数调整有重要指导意义。