烧结-冷却-余热回收系统热力学分析

采用热力学分析法剖析了烧结余热产生、转换与利用过程,绘制了烧结-冷却-余热回收系统的物流图和流图,建立了有关能量输出、转换与利用的评价指标,借此研究了国内某360m2烧结机的余热利用状况。结果表明:输出效率、转换效率、利用效率等指标可用来评价烧结余热回收等能量利用状况;烧结机、冷却机、余热锅炉、汽轮机发电4个环节的利用效率分别为0.30、0.52、0.71、0.39;目前烧结余热回收存在的主要问题是烧结烟气和冷却三段冷却废气所携带的显热尚未被利用;将烧结烟气和冷却三段废气余热用于点火煤气预热或锅炉给水预热,可使得烧结机和环冷机利用效率分别提高0.19和0.18。

Thermodynamic Analysis of Waste Heat Recovery for Sinter-Cooling System

The waste heat generation, transformation and utilization in sintering process were analyzed with thermodynamic analysis. The material flow diagram and exergy flow diagram of waste heat recovery system for sintering-cooling system were drawn. The energy output, conversion and utilization evaluation indexes were established. The state of waste heat recovery and utilization of a 360m2 sintering machine in China was analyzed. The results show that, exergy output efficiency, exergy conversion efficiency and exergy utilization efficiency can be used to evaluate waste heat utilization. The exergy utilization efficiency of sintering, cooling, boiler and turbine power generation is 0. 30, 0. 52, 0. 71 and 0. 39 respectively. Un-utilization of sensible heat of sinter flue gas and cooling gas in part 3 is the main problem. If the sensible heat was used for preheating gas or boiler feed water, the exergy utilization efficiency in sintering process and cooling process will increase to 0. 49 and 0. 70 separately.