Investigation of ash deposition and corrosion during circulating fluidized bed combustion of high-sodium, high-chlorine Xinjiang lignite
Investigation of ash deposition and corrosion during circulating fluidized bed combustion of high-sodium, high-chlorine Xinjiang lignite
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DOI：
10.1016/j.fuel.2017.11.011
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发表时间：
2018-02
期刊：
影响因子：
7.4
通讯作者：
Guoliang Song;Xiaobin Qi;Shaobo Yang;Zhao Yang
中科院分区：
文献类型：
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作者：
Guoliang Song;Xiaobin Qi;Shaobo Yang;Zhao Yang
以新疆高钠高氯褐煤为燃料，在0.4t/d循环流化床（CFB）试验系统上，采用不锈钢空冷探针研究了其灰沉积和腐蚀特性。在相同的烟气环境中，通过分别调节冷却风量为1.0 m3/h、3.0 m3/h和5.0 m3/h，获得了不同的探头壁温。分析了探头壁温变化，并通过一系列分析技术表征了沉积灰。实验结果证实了灰沉积对探头热流密度的扰动，且这种扰动由于壁温较低时灰沉积速率较快而增强。在低温条件下，Na-、Cl-、K-和Mg-等矿物物种的选择性沉积导致了较大的灰沉积量。富NaCl沉积灰的腐蚀伴随着金属基体的氧化。结果表明，不同金属的抗氧化性顺序为Ni > Cr > Fe。在腐蚀过程中，挥发性较强的金属氯化物是主要的腐蚀产物，由于它们的释放，导致沉积灰中存在空隙。这种腐蚀在高温下加速，并具有重复性。
A high-sodium, high-chlorine Xinjiang lignite was used as fuel in a 0.4 t/d circulating fluidized bed (CFB) test system to investigate ash deposition and corrosion characteristics using an air-cooled stainless steel probe. Different wall temperatures of the probe, exposed to the similar flue gas environment for 8 h, were achieved by adjusting cooling air flow separately at 1.0 m3/h, 3.0 m3/h and 5.0 m3/h. The probe wall temperature variation was analyzed, and deposited ash was characterized via a series of analytical techniques. Experimental results confirmed the disturbance of ash deposition to the heat flux through the probe, and this disturbance was enhanced due to the faster ash deposition rate at lower wall temperature. The selective deposition of mineral species including Na-, Cl-, K- and Mg-species occurred, resulting in a larger ash deposition amount on the lower-temperature probe. The corrosion caused by NaCl-rich deposited ash was accompanied with the oxidation of metallic matrix. It is found that the antioxidation of metals was in the order of Ni > Cr > Fe. During corrosion, metal chlorides with strong volatility were the main corrosion products, resulting in the presence of voids in deposited ash because of their release. This corrosion was accelerated at high temperatures and had repeatability.