为探索适用于超超临界二次再热机组的锅炉吹管工艺,以我国首台投产的二次再热机组锅炉为研究对象,提出并实践了一种降压法混合式管道吹洗方案.该方案综合了"一段吹管"的系统形式和"两段吹管"的操作特点,即将过热器、一次再热器、二次再热器及其附属管道一次性串联,吹扫时则分3部分进行,各部分独立打靶验收.针对新工艺实践过程中出现的吹管系数不达标问题,进行了现场测试和理论分析,提出了提高汽水分离器出口压力、增加临吹门开启个数等措施,基本消除了阀门的阻塞流效应,保证了管道的吹洗效果.最终靶板检验结果表明,降压法混合吹管实现了对二次再热机组锅炉各受热面的高质量吹扫,该吹管工艺对同类机组具有实际参考意义.%To explore suitable pipe-blowing methods for ultra supercritical double-reheat units, a decompression combined pipe-blowing method was proposed and put into practice on the domestic first double-reheat boiler. This new method is a combination of "one section pipe-blowing" method's structure and "two-section pipe-blowing" method's operating characteristics. The superheater, primary reheater, secondary reheater and its associated pipelines were connected in series in one time. The whole system is divided into three parts, and each part is purged and targeted separately. For the problem that the steam purge coefficient does not satisfy the standard, field test and theoretical analysis were carried out. Some measures, such as increasing the separator outlet steam pressure, opening multiple valves simultaneously, were taken into practice to eliminate the blocking flow effect and guarantee the purging quality. The final target plate tests results show that, the depression combined pipe-blowing method completed the purging of double-reheat boiler heating surfaces with high quality. This method can provide practical reference for other similar units.
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