The design and operation of a new clapboard-type Internal Circulating Fluidized-Bed gasifier is introduced in this paper. By setting clapboard in the middle of gasifier, bed layer in gasifier is divided into two regions that have different fluidization velocity, the incompletely reacted fuel or carbon in the high velocity region flows to the low velocity region companying with bed medium, and gasification reaction takes place in this region; still incompletely reacted fuel or carbon returns to the high velocity region in the bottom of gasifier, then gasification reaction further occurs. By this way, internal circulation in the gasifier was formed, gasification reaction time and efficiency increased. The experimental results indicate that gas yield (1.6 ∼ 1.9Nm3/kg fuel), gas heat values (5340kJ/Nm3 for wood chip fuel and 4880kJ/m3 for rice husk), and gasification efficiency (70%) can be obtained using this kind of gasifier in the optimal operational temperature range of 790∼850°C.

Wood gas generator

Fluidization

Husk

10.1115/fbc2005-78062

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Gasification Reactivity and Pore Structure Development: Effect of Intermittent Addition of Steam on Increasing Reactivity of PKS Biochar with CO₂

Energy & Fuels (2017)

Guozhang Chang Jianjun Xie Yanqin Huang Huacai Liu Xiuli Yin

Intermittent addition of steam was employed to increase the gasification reactivity of palm kernel shell biochar with CO2. The reactivity and variations in pore structures were initially assessed during CO2 and H2O-assisted gasification of biochars in a tube furnace, followed by characterization using thermogravimetric and surface area analysis. A quadratic orthogonal rotation regression combination design was used to investigate the effects of intermittent H2O addition on the total reaction time (t100%) of CO2 gasification. The achieving results showed that the formation of micropores with sizes of 0.3 to 1.5 nm was favored by CO2 gasification, while the reactivity of biochar was highly correlated with the surface area of micropores of 0.93 to 1.47 nm. A pore expansion effect was the primary phenomenon observed during H2O gasification, while the reactivity of biochar with H2O was closely related to the surface area of pores with specific sizes. CO2 and H2O react with the biochar on separate active sites, and micropores of 0.93–1.54 nm are produced in the early stage of H2O gasification, which enhances CO2 gasification. The intermittent addition of H2O increases the reactivity of biochar with CO2, such that the t100% value during CO2/intermittent H2O gasification is 31.89 and 15.80% lower than the values associated with using only CO2 or a simple mixture of CO2 and H2O.

Reactivity

Thermogravimetric analysis

Palm kernel

Tube furnace

Specific surface area

10.1021/acs.energyfuels.6b02859

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