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当前我国工业窑炉热效率偏低的主要原因是炉尾烟气带走的热损失太大,对一定品种和组份的燃料,要减少烟气带走的物理热损失,首先应把烟气余热回收到炉膛中来,降低最后排走的烟温,其次应控制合理的空气消耗系数。如何降低排走烟温的过程,亦即如何回收利用余热的过程。应遵守三条原则:(1)根据使用对象和工艺参数的不同,在(火用)损最小的前提下,按热质高低不同用能;(2)采用的回收余热方式应能回收最多的有效能;(3)利用回收后能量的形态,其效率应最高。根据这些原则对当前常见的三种余热回收方式进行了分析,认为余热回收应尽可能优先预热批料,其次预热空(煤)气,最后加热余热锅炉产生蒸汽。三者串联务使烟温低于200℃再排入烟囱。对单独预热批料、单独预热空气或两者串联后的燃料节约率分别列举实例计算,表明两者串联后燃料的节约率最高。既然余热利用应优先预热批料,那么炉型结构宜作相应的变化。
At present, the main reason for the low thermal efficiency of industrial kilns in our country is that the heat loss from the flue gas in the furnace tail is too large. To reduce the physical heat loss of flue gas taken from a certain species and components of fuels, firstly, Recycled to the furnace to reduce the last smoke away, and secondly, should control a reasonable air consumption factor. How to reduce the process of removing smoke temperature, that is, how to recycle the waste heat. Should comply with three principles: (1) Depending on the use of objects and process parameters, in the (exergy) loss under the premise of the different energy use according to the level of heat and quality; (2) the recovery of waste heat recovery method should be able to recover the most effective Can; (3) the use of energy recovery form, its efficiency should be the highest. According to these principles, the current common waste heat recovery methods are analyzed. It is concluded that waste heat recovery should give priority to preheating the batch material, then preheat the empty coal gas, and finally heat the waste heat boiler to generate steam. The three in series so that the smoke temperature below 200 ℃ and then discharged into the chimney. The calculation of the fuel saving rate of the preheated batch alone, the preheating of the air alone or the series connection of the two, respectively, gives an example calculation, indicating that the fuel saving rate is highest after the series connection. Since the waste heat utilization should give priority to preheating the batch, then the furnace structure should make the appropriate changes.