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    基于主成分分析的有机固废热解半焦与褐煤混燃特性研究

    Characteristics of organic solid waste pyrolysis semi-coke and lignite miscibility study based on principal component analysis

    • 摘要: 有机固废与燃煤机组耦合发电技术,是实现固废无害化处置及燃煤减耗降碳的有效途径之一。采用固定床反应器系统制取了废纺、木屑和橡胶3种典型有机固废热解半焦,分析了原料特性和热解温度对半焦产率和热值的影响。采用热重分析仪研究不同掺混比下有机固废半焦与褐煤的混燃特性及交互作用机制。结果表明:在热解过程中,低灰分且高纤维素含量的有机固废适合在较高温度下热解,而高灰分的石油化工类有机固废适合在较低温度下热解,废纺、木屑和橡胶的最佳热解温度分别为450、400、300 ℃。混燃过程中低挥发分的固废半焦与高挥发分煤种存在促进和抑制2种不同的交互作用,促进作用主要发生在着火和挥发分燃烧阶段,主要是由于半焦中丰富的孔隙结构增加了燃烧表面积,促进了氧气的传递和扩散;其次,促进作用也会发生在燃烧速率波动小的燃烧区间。抑制作用主要发生在固定碳燃烧和燃尽阶段,主要是由于燃烧前期挥发分燃烧消耗了大量氧气,以及重质挥发分裂解焦油对燃烧表面的覆盖,导致燃料燃烧后期传热传质条件变差,这种抑制作用也会随着燃料中无机组分的催化作用逐渐减弱。采用主成分分析法量化了混合燃料燃烧特性和交互作用的综合指数,得到废纺、橡胶和木屑半焦的最佳掺混比例分别为20%、40%以及80%。

       

      Abstract: The coupling of organic solid waste and coal-fired units to generate electricity is one of the effective ways to achieve harmless disposal of solid waste and reduction of coal consumption and carbon reduction. In this paper, three typical organic solid waste pyrolysis semi-cokes, namely, waste textile, wood chips and rubber, were produced using a fixed-bed reactor system, and the effects of raw material characteristics and pyrolysis temperature on semi-coke yield and calorific value were analyzed. A thermogravimetric analyzer was used to study the mixing characteristics and interaction mechanism between organic solid waste semi-coke and lignite at different mixing ratios. The results show that, in the pyrolysis process, organic solid wastes with low ash and high cellulose content were suitable for pyrolysis at higher temperatures, while petrochemical organic solid wastes with high ash content were suitable for pyrolysis at lower temperatures, and the optimal pyrolysis temperatures for waste textiles, wood chips and rubber were 450, 400, 300 ℃, respectively. There are 2 different interactions between low volatile solid waste semi-coke and high volatile coal species in the mixing and combustion process, the promotion mainly occurs in the ignition and volatile combustion stages, mainly due to the rich pore structure in the semi-coke which increases the combustion surface area and facilitates the transfer and diffusion of oxygen; secondly, the promotion also occurs in the combustion interval with small fluctuations in the combustion rate. The inhibitory effect mainly occurs in the stage of fixed carbon combustion and combustion exhaustion, mainly due to the large amount of oxygen consumed by the combustion of volatile components in the pre-combustion stage and the coverage of the combustion surface by the cracked tar of the heavy volatile components, which leads to the deterioration of heat and mass transfer conditions in the late stage of the combustion of the fuel, and this inhibitory effect will also be gradually weakened with the catalytic effect of the inorganic components in the fuel. The combined index of combustion characteristics and interactions of the blended fuels was quantified using total composition analysis, and the optimal blending ratios of 20%, 40% and 80% were obtained for waste textile, rubber and wood chip semi-coke, respectively.

       

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