Department of Mechanical and Nuclear Engineering, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates.
School of Chemical Engineering, National Technical University of Athens, Athens, Greece.
Environ Res. 2024 Jul 1;252(Pt 2):118597. doi: 10.1016/j.envres.2024.118597. Epub 2024 Mar 8.
Particle feeding plays a crucial role in the gasifier due to its effects on the efficiency and performance metrics of the thermochemical process. Investigating particle size distribution's impact on downdraft gasification reactor performance, this study delves into the significance of feedstock characteristics (moisture, volatile matter, fixed carbon, and ash contents) during the particle feeding stage. Various biomass wastes (date palm waste, olive pomace and sewage sludge) at diverse compositions and sizes are subjected to empirical determination of mass flow rates (MFR), power ratings, and storage times for each feedstock. The preheating process in the gasifier is considered, employing both an approximation and analytical solution. In addition, the influence of the equivalence ratio (ER) on the syngas yield is analyzed. The collected data reveals that for average particle size of 200 μm, the highest MFR (in g/min) are 0.518 ± 0.033, 7.691 ± 0.415, and 16.111 ± 1.050, for palm wood biomass, olive pomace and sewage sludge, respectively. Smaller particles (80 μm) led to extended storage times. Moreover, the lumped capacitance approximation method consistently underestimates preheating time, with a percentage error of 6.26%-17.08%. Response surface methodology (RSM) optimization analysis provides optimal gasification conditions for palm wood biomass, olive pomace, and sewage sludge with maximum cold gas efficiencies (CGEs) of 58.01%, 63.29%, and 52.27%. The peak conversion was attained at gasification temperatures of 1089.83 °C, 1151.93 °C, and 1102.91 °C for palm wood biomass, olive pomace, and sewage sludge, respectively. In addition, gasification equilibrium model determined optimal gasification temperatures as 1150 °C for palm biomass, 1200 °C for olive pomace, and 1150 °C for sewage sludge with respective syngas efficiencies of 59.62%, 64.13%, and 53.66%. Consequently, the examination of the dosing procedure, preheating dynamics, particle dimensions, ER, storage time, and their combined impacts offer practical insights to effectively control downdraft gasifiers in handling a variety of feedstocks.
颗粒给料在气化器中起着至关重要的作用，因为它会影响热化学过程的效率和性能指标。本研究探讨了颗粒尺寸分布对逆流气化反应器性能的影响，深入研究了给料阶段原料特性（水分、挥发物、固定碳和灰分含量）的重要性。对不同组成和尺寸的各种生物质废物（椰枣废料、橄榄渣和污水污泥）进行了质量流率（MFR）、功率等级和每个给料的储存时间的经验测定。考虑了气化器中的预热过程，采用了近似和解析解。此外，还分析了当量比（ER）对合成气产量的影响。收集的数据表明，对于平均粒径为 200 μm 的颗粒，椰枣废料、橄榄渣和污水污泥的最大 MFR（以 g/min 计）分别为 0.518 ± 0.033、7.691 ± 0.415 和 16.111 ± 1.050。较小的颗粒（80 μm）导致储存时间延长。此外，集总电容近似法始终低估预热时间，百分比误差为 6.26%-17.08%。响应面法（RSM）优化分析为椰枣废料、橄榄渣和污水污泥的气化提供了最佳条件，最大冷煤气效率（CGE）分别为 58.01%、63.29%和 52.27%。在椰枣废料、橄榄渣和污水污泥的气化温度分别为 1089.83°C、1151.93°C 和 1102.91°C 时，达到了最大转化率。此外，气化平衡模型确定了最佳气化温度为 1150°C 用于椰枣废料，1200°C 用于橄榄渣，1150°C 用于污水污泥，相应的合成气效率分别为 59.62%、64.13%和 53.66%。因此，对给料程序、预热动力学、颗粒尺寸、ER、储存时间及其综合影响的检查为有效地控制处理各种原料的逆流气化器提供了实际的见解。
