【作者】 黄本元；

【导师】 周怀春；

【作者基本信息】 华中科技大学 ， 热能工程， 2010， 博士

【摘要】 煤与煤气混烧是锅炉燃烧领域重要的研究内容,利用冶金行业的低热值燃料,解决钢铁厂高炉煤气与焦炉煤气的资源利用和保护环境,在电站锅炉上实现煤与煤气混烧特别是对低热值的高炉煤气大比例掺烧,可以起到很好的节能减排效果。本文研究了670t/h煤与煤气混烧锅炉的燃烧特性,构建了锅炉煤与高炉煤气焦炉煤气三种燃料同时掺烧的燃烧方案,搭建出煤／煤气掺烧的火焰图像检测系统,实现了煤气的大掺烧比例和全烧煤气。不同的煤气掺烧比例调整实验表明,高炉煤气投入比例增加,会使炉膛火焰中心温度下降,火焰中心上升,煤粉在炉膛中的停留时间缩短,飞灰含碳增加,同时会减小燃烧器区域的火焰黑度,降低主汽温度,并使排烟温度增加,锅炉效率下降；而焦煤投入后有利于锅炉燃烧。通过上述实验,得到了煤与煤气掺烧锅炉的最佳煤气掺烧比例。在此基础上,分析了煤气的掺烧对锅炉受热面的磨损原因及防范措施。通过对炉膛火焰图像监测系统的深入分析,提取了能实时反映炉膛燃烧状况的辐射强度参量,通过设定合理的阈值,实现了混烧锅炉燃烧稳定性的分析诊断和预警。煤／煤气混烧锅炉的一次灭火事故分析表明,该方法能有效地诊断燃烧工况异常现象,能给出锅炉不稳定燃烧的预警信号,避免锅炉灭火事故的发生。煤／煤气掺烧锅炉的烟气量增加,使主汽温度的波动变大。将辐射能作为前馈信号引入到670t/h煤与煤气混烧锅炉的主汽温控制回路,减小了主汽温度对燃烧的迟滞时间,改善了主汽温的品质,提高了蒸汽参数的稳定性。由于煤气的掺烧改变了原有的炉内燃烧组织方式,使混烧锅炉的燃烧优化调整难度加大。通过对不同风／燃比条件下的燃烧调整,以及辐射能信号与机组主要参数的监测和分析,获得了煤、高炉煤气、焦炉煤气的合理分配比例和混烧经济性的平衡点,形成了多燃料的在线燃烧调整控制策略,实现了煤／煤气掺烧锅炉的高效和低NOx排放的优化运行。更多还原

【Abstract】 Co-firing of coal with BFG (Blast Furnace Gas) and COG (Cove Oven Gas) is an important study in the boiler combustion field. With the development of national economy, co-firing of coal and gas study is becoming increasingly important. The objective of co-firing study should solve not only the safety and economy in the co-combustion of pulverized coal and gas, but also the problem of environmental emissions.Through an in-depth analysis of combustion characteristics of multi-fuel fired 670t/h boiler in a power plant, we established a combustion program of burning coal and gas mixture, identified the largest proportion of gas, and built a flame image detecting system used for testing coal/gas mixed combustion.By monitoring the real-time combustion conditions through the flame image detectors arranged in certain furnace position, we can extract the common combustion characteristic parameters, set a reasonable threshold, achieve the diagnosis of combustion stability of the multi-fuel fired boiler and early warning function. The data of three-dimensional temperature field displayed that at different ratios of blended gas, the furnace temperature characteristics will take on different changes. With increasing gas proportion, furnace flame core temperature drops, and flame center moves up. When combining these kinds of early warning signals with burning radiation, temperature level and the furnace flame ON/OFF signals, we can also make an effective integration of the boiler fire warning signals and FSSS systems, and ultimately develop a new method of combustion warning. Visualization system can reflect changes in operating conditions and power loads, create the corresponding relations between furnace average/maximum temperature and load, and then be utilized to optimize the unit’s part of the circuit using the radiation signal.Leading radiation energy as a feed-forward signal into the opium volume of the main steam temperature control loop can improve the quality of the temperature as well as the stability of steam parameters while blending with gas combustion. Experimental analysis indicates that at different air/fuel ratios, the radiation signal has a favorable corresponding relation with the actual generation power. Reasonable regulating the proportion of coal, the amount of BFG and COG through the previously mentioned corresponding relationship between them, and through the monitoring and analysis of the combustion and unit parameters lead to form a multi-fuel on-line combustion adjustment system and thus obtain better furnace combustion efficiency and low NOx emissions.更多还原