灰污热流探针模拟锅炉受热面灰沉积的研究

基于傅里叶导热定律，设计了一简单实用的灰污热流探针，以神木煤、黄陵煤、新汶水煤浆和新汶黑液水煤浆为研究对象，在0.25MW热态实验炉上用灰污热流探针模拟了灰沉积过程，研究了四种燃料灰沉积过程中的热流变化特性和灰沉积机理。结果表明，灰污探针能很好地模拟不同燃料的灰污形成过程，模拟结果与实际情况相吻合；灰粒的沉积速率和吸收热流的衰减速率主要取决于燃料本身特性，同时也受烟气温度的影响；通过对探针上灰污的表观物理特性、微观结构、元素构成和矿物相的分析，发现四种燃料的灰沉积机理是不同的，黑液水煤浆灰污中Na、K含量较高，主要物相为熔融温度很低的富Na霞石和无水芒硝，黄陵煤灰污含有较高的Fe、Ca、S，而水煤浆燃烧时Fe的沉积和富集是灰污形成的主要因素；四种实验燃料中，黑液水煤浆和黄陵煤的结渣趋势强于神木煤和水煤浆。

Simulation of ash depositing in heat transfer surface with heat flux probe

A simple and practical heat flux probe was designed according to one dimension steady state heat conduction law. Simulation on ash deposition process was made with heat flux probe when four representative fuels, including Shenmu coal, Huangling coal, Xinwen CWS and black liquor coal slurry, were burned in 0.25 MW test furnace. Heat flux variation and ash deposition characteristic was investigated for the fuels. The results indicate that ash probe can be applied well for simulating formation of ash deposition of different fuels. The simulation results are corresponding with the practical case. Ash depositing rate and heat flux decay rate depend on fuel characteristic mainly, meanwhile influenced by flue temperature. By analyzing apparent physical characteristic, microcosmic structure, elements composition and mineral phase of ash in probe, the result reveals ash deposition mechanism of four typical fuels is different. The content of Na, K and S in black liquor coal slurry ash is higher than else, and its dominant phase is nepheline and thenardite, with high Na and low fusing temperature. While Huangling coal ash deposited in probe is rich in Fe, Ca. Enrichment and deposition of Fe is the principal factor in ash forming process when Xinwen CWS is burned. Among the fuels tested, the slagging tendency of black liquor coal slurry and Huangling coal is stronger than that of Shenmu coal and CWS.