TY - JOUR
T1 - Biomass-Ash-Induced Agglomeration in a Fluidized Bed. Part 1: Experimental Study on the Effects of a Gas Atmosphere
AU - Ma, Teng
AU - Fan, Chuigang
AU - Hao, Lifang
AU - Li, Songgeng
AU - Song, Wenli
AU - Lin, Weigang
PY - 2016
Y1 - 2016
N2 - Fluidized beds have been widely applied to gasification and combustion
of biomass. During gasification, a high temperature is preferable to
increase the carbon conversion and to reduce the undesirable tar.
However, the high temperature may lead to a severe agglomeration problem
in a fluidized bed. Understanding of the agglomeration in various
atmospheres is crucial to optimize the design and operation conditions.
This study focuses on the effects of gases on agglomeration tendency
with different types of biomass, including corn straw, rice straw, and
wheat straw. The biomass ash samples are mixed with quartz sand and
fluidized by the gas mixtures of N2/CO2, N2/H2, and N2/steam
or by air. At 550 °C, the bed temperature is increased at the rate of 3
°C/min until defluidization occurs. In this way, the defluidization
temperature can be determined, which represents the agglomeration
tendency. The agglomerates are analyzed by scanning electron
microscopy–energy-dispersive X-ray spectrometry (SEM–EDS) for morphology
and elemental composition. Significant differences are observed on the
defluidization temperature (Td) and agglomeration mechanisms in different gas atmospheres. Td in H2
and steam atmospheres are much lower than that in air. It appears that,
in a steam atmosphere, the agglomeration of corn straw and rice straw
ash is predominantly coating-induced. The agglomeration in both H2 and air atmospheres are melting-induced. In a H2 atmosphere, K2SO4 in the ash samples disappears, caused by decomposition of K2SO4.
AB - Fluidized beds have been widely applied to gasification and combustion
of biomass. During gasification, a high temperature is preferable to
increase the carbon conversion and to reduce the undesirable tar.
However, the high temperature may lead to a severe agglomeration problem
in a fluidized bed. Understanding of the agglomeration in various
atmospheres is crucial to optimize the design and operation conditions.
This study focuses on the effects of gases on agglomeration tendency
with different types of biomass, including corn straw, rice straw, and
wheat straw. The biomass ash samples are mixed with quartz sand and
fluidized by the gas mixtures of N2/CO2, N2/H2, and N2/steam
or by air. At 550 °C, the bed temperature is increased at the rate of 3
°C/min until defluidization occurs. In this way, the defluidization
temperature can be determined, which represents the agglomeration
tendency. The agglomerates are analyzed by scanning electron
microscopy–energy-dispersive X-ray spectrometry (SEM–EDS) for morphology
and elemental composition. Significant differences are observed on the
defluidization temperature (Td) and agglomeration mechanisms in different gas atmospheres. Td in H2
and steam atmospheres are much lower than that in air. It appears that,
in a steam atmosphere, the agglomeration of corn straw and rice straw
ash is predominantly coating-induced. The agglomeration in both H2 and air atmospheres are melting-induced. In a H2 atmosphere, K2SO4 in the ash samples disappears, caused by decomposition of K2SO4.
U2 - 10.1021/acs.energyfuels.6b00164
DO - 10.1021/acs.energyfuels.6b00164
M3 - Journal article
VL - 30
SP - 6395
EP - 6404
JO - Energy & Fuels
JF - Energy & Fuels
SN - 0887-0624
IS - 8
ER -