预热燃烧具有燃料适应性广、负荷调节快及污染物排放低等优势，是一种新型的高效清洁燃烧技术。其中，煤粉流态化预热后产生的预热煤气既能反映预热过程中煤粉的改性程度，又对后续燃烧效率及NOx排放有重要影响。因此，煤粉流态化预热后产生的预热煤气是控制燃料转化及低NOx排放的关键。基于煤粉流态化预热转化过程，在温度可控的千瓦级煤粉预热燃烧试验平台上，研究了预热温度、循环流化床空气当量比、煤粉粒径对预热煤气生成特性的影响。结果表明，850～950 ℃，随预热温度升高，热解反应及气化反应增强，煤气中CO2体积分数下降，CO体积分数增加，H2体积分数先增加后不变，CH4体积分数则先增加后减小，煤气品质改善，热值由2.86 MJ/m3增至3.61 MJ/m3；循环流化床空气当量比从0.3增至0.5时，氧化反应增强，煤气中CO2体积分数增加，CO、H2、CH4体积分数降低，煤气热值由3.44 MJ/m3降至2.04 MJ/m3；随煤粉粒径增加，煤粉在提升管内停留时间延长，气化反应增强，煤气中CO2体积分数降低，CO、H2体积分数增加，CH4体积分数先增加后减小，煤气热值由2.30 MJ/m3增至3.63 MJ/m3。

The preheating combustion is a novel effective and clean combustion technology with the technical advantages of wide fuel adaptability, high load adjustment and low pollutant emission. The preheating coal gas generated after the pulverized coal fluidization preheating can not only reflect the modification degree of the pulverized coal in a preheating process, but also play an important role in subsequent combustion efficiency and NOx emission as well. Therefore, the preheating coal gas generated after the pulverized coal fluidization preheating is a key for controlling fuel conversion and low NOx emission. Based on the pulverized coal fluidized preheating conversion process, the effects of preheating temperature, air equivalence ratio of CFB, and pulverized coal particle size on the preheated gas generation characteristics were investigated in this paper on a kW-stage pulverized coal preheating combustion experimental platform with controllable temperature. The results show that the pyrolysis and gasification reaction are enhanced with the increase of preheating temperature in the range of 850-950 ℃. The volume fraction of CO2 in the gas decreases, the volume fraction of CO increases, the volume fraction of H2 increases firstly and then remains unchanged, while the volume fraction of CH4 increases firstly and then decreases. The gas quality is improved and the heat value increases from 2.86 MJ/m3 to 3.61 MJ/m3. When the air equivalent ratio of CFB increases from 0.3 to 0.5, the oxidation reaction is enhanced, the volume fraction of CO2 in the gas increases, the volume fractions of CO, H2 and CH4 decreases, and the heat value of gas decreases from 3.44 MJ/m3 to 2.04 MJ/m3. With the increase of pulverized coal particle size, the residence time of pulverized coal in the riser is prolonged and the gasification reaction is enhanced. The volume fraction of CO2 in the gas decreases, the volume fraction of CO and H2 increases, the volume fraction of CH4 increases first and then decreases, and the heat value of gas increases from 2.30 MJ/m3 to 3.63 MJ/m3.

0 引言

1 试验

   1.1 试验原料

   1.2 试验装置

   1.3 试验工况

   1.4 试验方法

2 结果与分析

   2.1 预热温度对预热煤气特性的影响

   2.2 循环流化床空气当量比对预热煤气特性的影响

   2.3 煤粉粒径对预热煤气特性的影响

3 结论