Chinese Journal of Chemical Engineering ›› 2021, Vol. 29 ›› Issue (1): 335-343.doi: 10.1016/j.cjche.2020.09.007

Previous Articles     Next Articles

Chemical looping gasification of sewage sludge using copper slag modified by NiO as an oxygen carrier

Nanhang Dong1, Ruiqiang Huo1,2, Ming Liu1,2, Lisheng Deng2,3, Zhengbing Deng4, Guozhang Chang5, Zhen Huang2,6, Hongyu Huang2,3   

  1. 1 School of Energy and Power Engineering, Northeast Electric Power University, Jilin 132012, China;
    2 Key Laboratory of Renewable Energy, Chinese Academy of Sciences(CAS), Guangzhou Institute of Energy Conversion, Guangzhou 510640, China;
    3 Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou), Guangzhou 511458, China;
    4 China United Engineering Corporation Limited, Hangzhou 310052, China;
    5 State Key Laboratory of High-efficiency Utilization of Coal and Green, Chemical Engineering, Ningxia University, Yinchuan 750021, China;
    6 Dalian National Laboratory for Clean Energy, CAS, Dalian 116023, China
  • Received:2020-04-06 Revised:2020-08-04 Online:2021-01-28 Published:2021-04-02
  • Contact: Zhen Huang
  • Supported by:
    The authors gratefully acknowledge the financial support by the National Natural Science Foundation of China (51776210), the National Key Research and Development Program of China (2018YFB0605405), the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (GML2019ZD0108), DNL Cooperation Fund CAS (DNL180205), Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering (2018-K15), and the Youth Innovation Promotion Association CAS (2018384).

Abstract: Chemical looping gasification (CLG) provides a novel approach to dispose the sewage sludge. In order to improve the reactivity of the calcined copper slag, NiO modification is considered as one of the good solutions. The copper slag calcined at 1100 ℃ doped with 20 wt% NiO (Ni20-CS) was used as an oxygen carrier (OC) in sludge CLG in the work. The modification of NiO can evidently enhance the reactivity of copper slag to promote the sludge conversion, especially for sludge char conversion. The carbon conversion and valid gas yield (Vg) increase from 67.02% and 0.23 m3·kg-1 using the original OC to 78.34% and 0.29 m3·kg-1 using the Ni20-CS OC, respectively. The increase of equivalent coefficient (Ω) facilitates the sludge conversion and a suitable Ω value is determined at 0.47 to obtain the highest valid gas yield (0.29 m3·kg-1). A suitable steam content is assigned at 27.22% to obtain the maximum carbon conversion of 87.09%, where an acceptable LHV of 12.63 MJ·m-3 and Vg of 0.39 m3·kg-1 are obtained. Although the reactivity of Ni20-CS OC gradually decreases with the increase in cycle numbers because of the generation of NiFe2O4-δ species, the deposition of sludge ash containing many metallic elements is beneficial to the sludge conversion. As a result, the carbon conversion shows a slight uptrend with the increase of cycle numbers in sludge CLG. It indicates that the Ni20-CS sample is a good OC for sludge CLG.

Key words: Chemical looping gasification (CLG), Copper slag, NiO, Sludge, Oxygen carrier (OC)