In the first and third stage superheater and two-stage high temperature reheater in a 1000 MW double-reheat unit tower-type boiler, the tube wall temperature is far away over the limit temperature. To solve this problem, many measures related to optimization and modification of the heating surfaces have been proposed, on the basis of the site operation data and simulation thermodynamic calculation results. By cutting two outboard tubes on the secondary superheater, the heat absorption area of the superheater decreased by 28％. By installing throttle short tubes on both sides of the high pressure and low pressure reheaters, the coolant flow rate of the central tube group increased. For some of the seriously over-temperature tubes, part of the high pressure high temperature reheater tubes were cut short and the low pressure high temperature reheater was painted with thermal insulation material. These measures greatly reduced heat absorption of the relevant tubes and the tube wall temperature reduced dramatically. After the comprehensive retrofitting and adjustment, the over-temperature problem of the superheater was basically solved during the boiler load change process. Under full load working conditions, the superheated steam temperature and two-stage reheat steam temperature approached the design value. No metal tube wall temperature alarmed. The comprehensive renovation plan greatly improves the safety and economy of the boiler operation.%针对1000 MW二次再热机组塔式锅炉一级、三级过热器以及两级高温再热器金属壁温大范围超限问题,结合现场运行数据与模拟热力计算结果,提出了多项过热器与再热器的优化改造措施.具体改造措施为:通过将二级过热器外圈2根管子切除,减少了过热器受热面积;将低压高温再热器和高压高温再热器两侧管屏加装节流短管,增加了中部管屏冷却介质流量;针对部分超温严重的管子,通过截短高压高温再热器部分管段,以及在低压高温再热器中实施隔热喷涂,大大减少了两者的吸热量,降低了管子壁温.综合改造调整后,锅炉升降负荷过程基本消除了过热器超温现象,满负荷下各级过热汽温与两级再热汽温接近设计值,金属壁温无报警,大大提高了锅炉运行的安全性和经济性.
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