超临界机组锅炉滑停对氧化脱落的影响

Effect of Sliding Stop of Supercritical Unit Boiler on Oxidation Shedding

当前由上海锅炉厂生产的350 MW超临界锅炉在进行滑停和正常停炉过程中,高温受热面奥氏体不锈钢材质,从高温降至低温时,对管壁内生成的氧化皮脱落情况进行对比分析发现:随着锅炉累计运行时间逐渐增长,锅炉高温受热面管壁内形成的氧化皮也逐步增厚,由于氧化皮与受热面管材的膨胀系数不同,温度变化率超出允许范围时,氧化皮会从管屏金属内壁上剥脱,一旦大量氧化皮集中剥落,就会在受热面弯头处堵塞管道引起爆管等等问题。文中就超临界锅炉在滑停过程中氧化皮脱落现象进行了探讨,并提出了锅炉滑停过程中的防控措施。

At present,the 350 MW supercritical boiler produced by Shanghai Boiler Plant is in the process of sliding stop and normal shutdown,and the high temperature heated surface austenitic stainless steel material,when the temperature is lowered from high temperature to low temperature,the scale falling off in the pipe wall The comparative analysis shows that as the cumulative running time of the boiler gradually increases,the scale formed in the wall of the high-temperature heating surface of the boiler is gradually thickened.Because the expansion coefficient of the oxide surface and the heating surface tube are different,and the temperature change rate exceeds the allowable range,The scale will be peeled off from the inner wall of the tube panel metal.Once a large amount of scale is peeled off,the tube will be blocked at the bend of the heated surface to cause a tube explosion.In this paper,the phenomenon of scale peeling during the sliding process of supercritical boilers is discussed,and the prevention and control measures during the process of boiler slippage are proposed.