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Ash Agglomeration and Deposition during Combustion of Poultry Litter in a Bubbling Fluidized-Bed Combustor
被引:32
作者:
Lynch, Deirdre
[1
,2
]
Henihan, Anne Marie
[1
]
Kwapinski, Witold
[1
]
Zhang, Lian
[2
]
Leahy, James J.
[1
]
机构:
[1] Univ Limerick, Dept Chem & Environm Sci, Limerick, Ireland
[2] Monash Univ, Dept Chem Engn, Clayton, Vic 3800, Australia
关键词:
PULVERIZED COAL;
BIOMASS FUELS;
PART;
INORGANIC ELEMENTS;
WASTE COMBUSTION;
FOULING TENDENCY;
RAPESEED CAKE;
GAS-PHASE;
BEHAVIOR;
GASIFICATION;
D O I:
10.1021/ef400744u
中图分类号:
TE [石油、天然气工业];
TK [能源与动力工程];
学科分类号:
0807 ;
0820 ;
摘要:
In this study, we have characterized the ash resulting from fluidized bed combustion of poultry litter as being dominated by a coarse fraction of crystalline ash composed of alkali-Ca-phosphates and a fine fraction of particulate K2SO4 and KCl. Bed agglomeration was found to be coating-induced with two distinct layers present. The inner layer (0.05-0.09 mm thick) was formed due to the reaction of gaseous potassium with the sand (SiO2) surface forming K-silicates with low melting points. Further chemical reaction on the surface of the bed material strengthened the coating forming a molten glassy phase. The outer layer was composed of loosely bound, fine particulate ash originating from the char. Thermodynamic equilibrium calculations showed slag formation in the combustion zone is highly temperature-dependent, with slag formation predicted to increase from 1.8 kg at 600 degrees C to 7.35 kg at 1000 degrees C per hour of operation (5.21 kg of ash). Of this slag phase, SiO2 and K2O were the dominant phases, accounting for almost 95%, highlighting the role of K-silicates in initiating bed agglomeration. The remaining 5% was predicted to consist mainly of Al2O3, K2SO4, and Na2O. Deposition downstream in the low-temperature regions was found to occur mostly through the vaporization-condensation mechanism, with equilibrium decreasing significantly with decreasing temperatures. The dominant alkali chloride-containing gas predicted to form in the combustion zone was KCl, which corresponds with the high KCl content in the fine baghouse ash.
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页码:4684 / 4694
页数:11
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