SG-1025/18.3-M835亚临界一次再热控制循环锅炉应用卧式相变换热器技术节能改造

Application of horizontal phase change heat exchanger technology to improve energy-saving for SG-1025/18.3-M835 subcritical primary reheat control circulating boiler

卧式相变换热器技术虽然在150MW以下诸多自备电厂或者热电联产火力发电机组取得成功应用,并获得良好的经济效益,但在某300MW大型火力发电机组锅炉上应用还是首次。利用卧式相变换热器最低壁温可调可控的技术特点,将额定负荷下140℃的排烟温度降至120℃左右,回收余热用于加热6#低加进口凝结水,通过排挤6#低加抽汽去汽轮机做功,提高汽轮机效率,降低机组发电标准煤耗达1.36g/kW·h,节能增效幅度可观。卧式相变换热器蒸发段最低壁温实现了自动控制,即使在锅炉较低负荷运行的情况下,最低壁温也始终处于100℃以上,确保了锅炉的安全可靠运行。翅片管的水平布置,对减少积灰具有积极作用。高效传热的翅片管和低频声波吹灰器的联合使用为受热面的清洁创造了有利条件。

Although horizontal phase-change heat exchanger have been successfully used in boiler of Captive Power Plant, heat power cogeneration thermal generator set rating 150MW and below, where good economic profit was realized, it was the first time that the application of the phase-change heat exchanger in 300MW power station boiler. By exploiting of the adjustable and controllable of the tube wall temperature（TWT） of the horizontal phase-change heat exchanger, the exhaust gas temperature leavingboiler shall reduce from 140℃ to about 120℃ at the rated duty. The recovered residual heat is used for heating 6# low plus inlet condensate which is done on the steamturbine by squeezing out 6# low and pumping steam to reduce the standard coal consumption 1.36g/kWh. The efficiency of energy saving is very remarkable. Horizontal phase-change heat exchanger can automatically control the tube wall temperature（TWT）, where the TWT can be hold above 100℃ even in case of lower boiler duty to insure the safety of the boiler. The horizontal arrangement of the finned tubes can minimize the dust deposited. The combination of higher heat transfer coefficient and the application of the low frequency acoustic soot blower will contribute the cleaning of the heating surface.