title: Characteristics of ammonia emission during thermal drying of lime sludge for co-combustion in cement kilns.
abstract: Thermal drying was used to reduce sludge moisture content before co-combustion in cement kilns. The characteristics of ammonia (NH3) emission during thermal drying of lime sludge (LS) were investigated in a laboratory-scale tubular dry furnace under different temperature and time conditions. As the temperature increased, the NH3 concentration increased in the temperature range 100-130°C, decreased in the temperature range 130-220°C and increased rapidly at >220°C. Emission of NH3 also increased as the lime dosage increased and stabilized at lime dosages>5%. In the first 60 min of drying experiments, 55% of the NH3 was released. NH3 accounted for about 67-72% of the change in total nitrogen caused by the release of nitrogen-containing volatile compounds (VCs) from the sludge. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy revealed that the main forms of nitrogen in sludge were amides and amines. The addition of lime (CaO) could cause conversion of N-H, N-O or C-N containing compounds to NH3 during the drying process.
authors.affiliation: a College of Environmental Science and Engineering , Tongji University , Shanghai 200092 , People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Jingcheng
authors.initials: J
authors.lastname: Xu
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.forename: Haihua
authors.initials: H
authors.lastname: Cao
authors.forename: Xiang-Feng
authors.initials: XF
authors.lastname: Huang
authors.forename: Guangming
authors.initials: G
authors.lastname: Li
mesh_terms: D000393:Air Pollutants / Q000737:chemistry / Q000302:isolation & purification*; D000641:Ammonia / Q000737:chemistry / Q000302:isolation & purification*; D017610:Calcium Compounds / Q000737:chemistry*; D003890:Desiccation / Q000379:methods*; D006361:Heating / Q000379:methods; D017745:Incineration / Q000379:methods*; D010087:Oxides / Q000737:chemistry*; D012037:Refuse Disposal / Q000379:methods; D012722:Sewage / Q000737:chemistry*
chemical_list: D000393:Air Pollutants; D017610:Calcium Compounds; D010087:Oxides; D012722:Sewage; D000641:Ammonia; C016538:lime
keywords: ammonia emission; cement kilns; co-combustion; lime sludge; thermal drying