Pore structure of sludge char and simultaneously NO removal characteristics in the treated flue gas from Ca-L

Abstract

A novel system for the comprehensive utilization process of treated flue gas from Calcium based looping (Ca-L) is proposed to realize the municipal sludge char (MSC) production and simultaneously NO removal. In this study, the pore characteristic of MSC was studied by low pressure nitrogen adsorption (LP-N2GA) analysis and fractal mechanism. NO removal characteristics of sludge and the contribution of MSC were also investigated. Besides, the migration of nitrogen functional groups in MSC under different oxygen conditions was studied by X-ray photoelectron spectroscopy (XPS). Results show that the pore structure of MSC was the best when the pyrolysis time was 60 s and pyrolysis temperature was 900 °C. Higher concentrations of oxygen and CO2 are not conducive to the good development of pore structure. At the same time, the simultaneous removal of NO was achieved, and the peak NO reduction rate was 73.12%. P-N content in solid samples disappears after pyrolysis. N-6, and N-5 contents decrease, while N-X content in MSC increases at higher oxygen concentration in the flue gas, proving that the oxygen in the flue gas destroys the reducing atmosphere suitable for removing NO.