基于吉布斯自由能最小化原理,采用HSC Chemistry 6.0软件,对污泥化学链气化过程中NOx前驱物（NH3和HCN）与Fe2O3载氧体的氧化还原行为进行了热力学模拟。基于污泥热解实验中NOx前驱物的含量,计算载氧体与污泥的摩尔比（OC/SS）对NH3、HCN以及NH3和HCN混合气氧化过程的影响。热力学模拟结果表明：Fe2O3能显著促进NOx前驱物的氧化和裂解,主要生成N2,几乎无NOx生成;当NH3、HCN以及混合气（NH3和HCN）分别作为还原剂时,其最优OC/SS分别为0.02、0.04和0.05;由于HCN还原性强于NH3,其氧化速率较快。基于Fe2O3/Al2O3混合物（FeAl）载氧体,实验对比了污泥化学链气化与污泥热解过程中NOx前驱物的释放特性,发现Fe2O3能显著降低烟气中NOx前驱物的产率,NH3和HCN产率分别下降32%和62%。实验结果与热力学模拟结果一致。
Based on the Gibbs free energy minimization principle, thermodynamic analysis and process simulation of the redox reactions between the NOx precursors (NH3 and HCN) and Fe2O3 (oxygen carrier) during the sludge chemical looping gasification were performed using the software of HSC Chemistry 6.0. According to the content of NOx precursors during the sludge pyrolysis, the effect of the molar ratio of oxygen carrier to the sludge (OC/SS) on the oxidation of NH3, HCN, and the mixed gas of NH3 and HCN were investigated. The simulation results showed that the oxidation of NOx precursors was effectively promoted by Fe2O3, the N element was mainly converted to N2 and almost no NOx was formed. The OC/SS ratio of 0.02, 0.04, and 0.05 were determined to achieve the complete conversion of NOx precursors as well as minimize the amount of oxygen carrier when the NH3, HCN, and the mixed gas of NH3 and HCN were used as the reductants, respectively. Additionally, the oxidation rate of HCN was higher than that of NH3 due to the stronger reducibility of HCN. Furthermore, the yields of NOx precursors during the sludge pyrolysis and the sludge chemical looping gasification were compared in a fixed bed. It was found that the yields of NOx precursors in the flue gas were significantly reduced by Fe2O3, and the yields of HCN and NH3 decreased by 62% and 32%, respectively. The thermodynamic analysis was validated by the experiment results, and the chemical looping gasification of sludge was beneficial to inhibit the generation of the NOx.
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