1000MW核电汽轮机高中压缸装机过程汽封间隙计算分析

Calculation and Analysis of a 1000MW Nuclear Steam Turbine High and Intermediate Pressure Casing Seal Clearance in Installation Process

百万千瓦级核电汽轮机往往体积和重量很大,受到自身重力的影响在装机过程中会产生一定的变形,从而改变通流部分的汽封间隙。间隙的变化不仅会影响机组的热效率,还可能导致动静部分发生碰摩,影响机组的安全运行。而且受到结构和测量工艺的限制,精确测量装机过程的变形存在一定困难。通过创建某1000MW核电汽轮机高中压缸模型,对安装过程的变形进行了数值计算,利用缸体不同状态下的相对变形量分析得到汽封间隙的变化情况。结果表明,汽封间隙在扣上隔板时增加,扣上缸时继续增加,紧螺栓时减少,换支撑后再次增加,紧螺栓过程间隙变化大于其它过程;整个装机过程中汽封间隙增加0.4mm~0.5mm,在中压第一级隔板附近间隙变化量最大,达到0.52mm。

1000MW nuclear steam turbines are often very large in size and weight.Under the influence of their own gravity,they will undergo certain deformations in installation process,thereby changing seal clearance of steam passage.The change of clearance will not only affect the thermal efficiency of the unit,but may also cause friction between the static and dynamic parts,which will affect the operation of the unit.Besides due to the limitation of structure and measurement technology,it is hard to accurately measure the deformation in installation process.By establishing a high and intermediate pressure casing model of a 1000MW nuclear steam turbine,the deformation in installation process is numerically calculated,and the change of seal clearance is obtained by analyzing the relative deformation of the casing under different conditions.The results show that the seal clearance increases in installing upper diaphragms,continues to increase in installing the upper casing,decreases during bolting flange bolts,and increases again after replacing the support.The clearance change during bolting flange bolts is greater than other processes;the seal clearance increases by 0.4 to 0.5mm during the whole installation process.The largest clearance change is near the first-stage of the intermediate pressure casing,reaching 0.52mm.