摘要
煤气化技术是煤化工行业的一项重要技术，是煤基化学品、煤基液体燃料、IGCC 发电、多联产系统、制氢和燃料电池等各种加工工业的基础。气化过程会产生大量灰渣，年排放量超过数千万吨，累积量达数亿吨。因此，迫切需要研究处理灰渣的方法。我们在管式炉中进行了气化细灰（GFA）的燃烧试验，并对传统的缩核模型进行了改进，以准确预测不同温度（900°C-1500°C）下的燃烧行为。我们将反应温度分为三个范围，即未熔化燃烧（T<DT）、熔化燃烧（T>FT）和混合燃烧（DT<T<FT）。未熔化燃烧和熔化燃烧的反应速率差异很大。在DT＜T＜FT范围内，气化细灰颗粒中的灰分以液固态存在，粘度高，流动性低，但仍粘附在颗粒表面，延长了颗粒的燃尽时间。在T＞FT时，气化细灰颗粒表面灰分脱落，残碳和气相反应物几乎不再受到扩散阻力的影响，从而大大加快了内部残碳的反应速度。为了更准确地预测熔融燃烧过程，对缩核模型（SCM）的时间项进行了修正，并定义了 T＞FT 的有效扩散系数。
Abstract
Coal gasification technology is a prominent technology in the coal chemical industry and serves as the fundamental basis for various process industries, including coal-based chemicals, coal-based liquid fuels, Integrated Gasification Combined Cycle (IGCC) power generation, multi-generation systems, hydrogen production, and fuel cells. The gasification process generates significant quantities of ash residue, with annual emissions exceeding tens of millions of tons and accumulation reaching hundreds of millions of tons. Accordingly, there is an urgent need to investigate methods for its disposal. The combustion of gasified fine ash (GFA) was conducted in a tube furnace, and the conventional shrinking core model was modified to accurately predict the combustion behaviors at different temperatures (900°C–1500°C). We divided the reaction temperatures into three ranges, which is defined as unmelted combustion (T<DT), melted combustion (T>FT) and mixed combustion (DT<T<FT) (DT: deformation temperature; FT: flow temperature). There is a large difference between the reaction rates of unmelted and melted combustion of GFA. In the range of DT<T<FT, the ash in the grains existed as a liquid-solid state, and had high viscosity and low fluidity, but still adhered to the grain surface, which prolonged the grain burnout time. At T>FT, the surface ash of GFA grains fell off, and the residual carbon and gas-phase reactants were nearly no longer affected by the diffusion resistance, thus significantly accelerated the reaction of internal residual carbon. In order to predict the melt combustion process more accurately, the time term of the shrinkage core model (SCM) is modified, and the effective diffusion coefficient of T>FT is defined.
关键词
fine ash /
melting combustion /
kinetic model /
combustion characteristics
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Key words
fine ash /
melting combustion /
kinetic model /
combustion characteristics
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脚注
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基金
This study is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA21040602), and Youth Innovation Promotion Association, Chinese Academy of Sciences (Grant No. 2020150).
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版权
Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2023
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