Ignition Behavior of Bio-Coke (Highly Densified Biomass Fuel) in High-Temperature Air Flows
Ignition Behavior of Bio-Coke (Highly Densified Biomass Fuel) in High-Temperature Air Flows
复制标题
生物焦（高密度生物质燃料）在高温气流中的着火行为
DOI：
10.1299/jtst.6.111
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发表时间：
2011
影响因子：
1.2
通讯作者：
O. Fujita
中科院分区：
文献类型：
--
作者：
Hiroyuki Ito;Y. Sakai;T. Ida;Y. Nakamura;O. Fujita
研究了一种新开发的生物质型煤——生物焦（BIC）的着火行为。该燃料具有独特的特点，如经济优势，因为它的生物质资源的多功能性，高体积热值，因为它的高密度（1300公斤/立方米，比普通木屑颗粒的两倍或更多）和高机械强度。圆柱形BIC块（直径48毫米，长度85毫米）在实际燃烧炉中使用燃料时很重要，在高温气流（473-873 K, 550-750 NL/min）中进行了点火特性研究。在实验中，将预热空气吹到BIC气缸的底表面，观察底表面的点火行为，并监测表面温度和随时间变化的质量损失率。结果表明：点火模式有两种；(1)在高温条件下（T≥598K），固体表面点火先于气相点火；(2)在相对低温条件下，气相点火同时发生表面点火。每种模式的外观取决于空气温度，流速和燃料含水量方面的预热空气供应条件。挥发性气体的演化速率与BIC型煤内部温度分布密切相关，温度分布取决于加热速率，这意味着燃料内部温度分布的变化可能是观察到的点火模式出现的原因之一。指出在控制BIC型煤的着火行为时，必须考虑燃料内部的温度分布。
The ignition behavior of a newly developed biomass briquette, Bio-coke (BIC), is investigated. The fuel has unique features such as economical advantages for its versatility of biomass resources, high volumetric calorific value because of its high density (1300 kg/m3; twice or more than that of ordinary wood pellets) and high mechanical strength. The ignition characteristics of cylindrical BIC blocks (48 mm in diameter and 85 mm in length), important when using the fuel in actual combustion furnaces, are investigated in high temperature air flows (473-873 K, 550-750 NL/min.). In the experiments, preheated air is blown onto the bottom surface of BIC cylinders and the ignition behavior of the bottom surface is observed monitoring the surface temperature as well as the time dependent mass loss rates. The results show two ignition modes; (1) solid surface ignition preceding gas-phase ignition in high air temperature conditions (T≥598K), and (2) gas-phase ignition accompanied by simultaneous surface ignition occurring at relatively low air temperature conditions. The appearance of each mode depends on the preheated air supply condition in terms of the air temperature, flow velocity, and moisture content of the fuel. The rate of evolution of volatile gases is closely correlated with the temperature distribution inside the BIC briquette which depends on the heating rate, implying that variations in the temperature distribution inside the fuel could be one reason for the appearance of the observed ignition modes. It is suggested that the temperature distribution inside the fuel has to be taken into account in the control of the ignition behavior of BIC briquettes.