In this study, syngas preparation by chemical looping gasification (CLG) process is investigated through theory and experiment. The starting materials for the syngas are low quality lignite, which cannot be used for other applications, and phosphogypsum (PG), the byproduct of wet phosphoric acid. The results show that the CO production is mainly due to the following reaction: (CaSO₄ + 4C → CaS + 4CO) and (C + CO₂ → 2CO), while the main reactions of H₂ generation are (CO₂ + H₂O(g) + 2CH₄ → 3CO + 5H₂) and (C + H₂O(g) → CO + H₂). The analysis results indicate that high temperature and water vapor content are detrimental for phosphogypsum recycling. Furthermore, after three times recycling of phosphogypsum, some sintering is observed. The composition of syngas is very important for the corresponding applications. Therefore, the relationships between reaction factors and products are also investigated. The results of Analysis of Variance (ANOVA) show that H₂ and CH₄ generation are strongly dependent on water vapor content. The influence of the different factors on CO yield is in the following order: PG/lignite’s molar ratio > temperature > water vapor. Among the three factors, reaction temperature effect on CO₂ generation is less than that of the other factors. Moreover, the reaction temperature and the PG/lignite’s molar ratio have a great influence on lignite decomposition. The results of this work can provide some guidance for preparing syngas with the desired composition by the CLG process.

中文翻译：

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磷石膏载氧褐煤化学环化气化制合成气的反应机理

在这项研究中，通过理论和实验研究了通过化学回路气化（CLG）工艺制备合成气。合成气的原料是不能用于其他应用的低质量褐煤，以及湿磷酸副产品磷石膏（PG）。结果表明，CO的产生主要归因于以下反应：（CaSO ₄ + 4C→CaS + 4CO）和（C + CO ₂ →2CO），而产生H ₂的主要反应是（CO ₂ + H _2） O（g）+ 2CH ₄ →3CO + 5H ₂）和（C + H ₂ O（g）→CO + H ₂）。分析结果表明，高温和水蒸气含量对磷石膏的回收有害。此外，在磷石膏循环三遍之后，观察到一些烧结。合成气的组成对于相应的应用非常重要。因此，还研究了反应因子与产物之间的关系。方差分析（ANOVA）的结果表明，H ₂和CH _4的生成强烈依赖于水蒸气含量。不同因素对CO收率的影响顺序如下：PG /褐煤的摩尔比>温度>水蒸气。在这三个因素中，反应温度对CO _2的影响世代比其他因素要少。而且，反应温度和PG /褐煤的摩尔比对褐煤的分解有很大的影响。这项工作的结果可以为通过CLG工艺制备具有所需组成的合成气提供一些指导。