摘要
Calcium looping realizes CO_(2)capture via the cyclic calcination/carbonation of CaO.The combustion of fuel supplies energy for the calciner.It is unavoidable that some unburned char in the calciner flows into the carbonator,generating CO due to the hypoxic atmosphere in the carbonator.CO can reduce NO in the flue gases from coal-fired power plants.In this work,NO removal performance of CO in the carbonation stage of calcium looping for CO_(2)capture was investigated in a bubbling fluidized bed reactor.The effects of carbonation temperature,CO concentration,CO_(2)capture,type of CaO,number of CO_(2)capture cycles and presence of char on NO removal by CO in carbonation stage of calcium looping were discussed.CaO possesses an efficient catalytic effect on NO removal by CO.High temperature and high CO concentration lead to high NO removal efficiency of CO in the presence of CaO.Taking account of better NO removal and CO_(2)capture,the optimal carbonation temperature is 650℃.The carbonation of CaO reduces the catalytic activity of CaO for NO removal by CO due to the formation of CaCO_(3).Besides,the catalytic performance of CaO on NO removal by CO gradually decreases with the number of CO_(2)capture cycles.This is because the sintering of CaO leads to the fusion of CaO grains and blockage of pores in CaO,hindering the diffusion of NO and CO.The high CaO content and porous structure of calcium-based sorbents are beneficial for NO removal by CO.The presence of char promotes NO removal by CO in the carbonator.CO_(2)/NO removal efficiencies can reach above 90%.The efficient simultaneous NO and CO_(2)removal by CO and CaO in the carbonation step of the calcium looping seems promising.
基金
Financial supports from the National Natural Science Foundation of China(51876105)
the Joint Foundation of National Natural Science Foundation of China and Shanxi Province for coal-based low carbon(U1510130)
Shandong Provincial Natural Science Foundation(ZR2020ME188)
the Fundamental Research Funds of Shandong University(2018JC039)
the program for Outstanding PhD candidate of Shandong University。
