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.
DENG Zheng-bing
,
HUANG Zhen
,
ZHENG An-qing
,
HE Fang
,
WEI Guo-qiang
,
ZHAO Zeng-li
,
LI Hai-bin
. Thermodynamic Analysis and Experimental Study of Nitrongen Migration during the Sludge Chemical Looping Gasification Using Iron-Based Oxygen Carriers[J]. Advances in New and Renewable Energy, 2019
, 7(3)
: 199
-206
.
DOI: 10.3969/j.issn.2095-560X.2019.03.001
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