水泥分解炉内生活垃圾与煤粉燃烧特性分析和技改建议
Analysis of combustion characteristics of RDF and coal in the cement calciner and suggestions for technical improvement
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摘要: 将生活垃圾制备成垃圾衍生燃料（RDF），再投入水泥分解炉内进行燃烧处理是生活垃圾无害化处置的重要途径。与煤粉相比，RDF在分解炉内的燃烧与运动特性存在较大差异，从而对分解炉的正常运转产生较大影响。通过检测分析、热工计算和计算流体动力学模拟（CFD）等手段，对比了RDF与煤粉在燃烧、运动特性等方面存在的差异。结果表明，与煤粉相比，RDF的水分、灰分含量偏高，固定碳含量偏低, 单位RDF燃烧理论空气量只有煤粉的14.5%。入炉煤粉的特征粒径为20 μm，RDF为10 mm；粒径小于10 mm的RDF喂入分解炉后随烟气向下游流动，但大于10 mm的直接向下运动，并在分解炉缩口和中部形成循环。经过空气干燥、粉磨后的RDF颗粒着火温度为235~242 °C，煤粉着火温度为375 °C，然而考虑实际使用时入炉RDF水分含量高、尺寸大等，其在分解炉内燃烧速度通常较煤粉慢。为此，建议水泥企业在对RDF进行准确的工业分析和元素分析基础上，通过热工标定、CFD模拟等手段优化RDF处置尺寸与喂入位置，确保RDF在分解炉内完全燃烧。
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关键词:
- 水泥分解炉 /
- 垃圾衍生燃料（RDF） /
- 燃烧特性 /
- 运动特性
Abstract: Refuse derived fuel (RDF) co-processed in the cement calciner is one of the harmless ways to dispose the domestic waste. Compared with the coal, RDF has many differences on the combustion and motion characteristics, which greatly impact the normal operations of the calciner. Test and analysis, thermal calculation and computational fluid dynamics (CFD) were used to understand the differences between the coal and RDF. Results showed that RDF had a higher water and ash content, and a lower fixed carbon content than the coal. Besides, the theoretical air volume need for the unit RDF combustion was only 14.5% of the air volume for the unit coal. The characteristic particle diameters for the coal and RDF fed into the calciner were 20 μm and 10 mm, respectively. The RDF particles with diameter smaller than 10 mm were carried by flue gas downstream as they were fed into the calciner, while the RDF particles with diameter larger than 10 mm fell down to the throat of the calciner, and then were carried by high speed gas stream to rise, which formed a RDF circulation between the feed spot and calciner throat. The ignition temperature for the air-dried and grinded RDF was 235~242 °C, and for the coal was 375 °C. However, RDF burned slowly in the calciner due to its high content water content and large size. Suggestions were given to the cement enterprises to conduct the proximate analysis and ultimate analysis of the RDF at first, and make it clear of the calciner combustion condition by the thermal condition calibration and CFD, and optimize the RDF feeding size and position to ensure the RDF burning itself out in the calciner. -
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