典型汽机事故

&nbsp;11时31分，值长刘宝洪令汽机第二次挂闸冲转，当 &nbsp;<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;转速达到2156转／分时，自动主汽门及调速汽门再次关闭。汽机班长郑云青、热工分场专工胡意成、运行副总孟繁荣分别让郝宝伟将汽机所有保护退出。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;11时34分，值长刘宝洪令第三次挂闸冲转，转速升至2150转／分时，自动主汽门及调速汽门又一次关闭。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　11时38分，值长刘宝洪请示省调，同意7号机停机检查。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　11时42分，7号炉熄火。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　三、事故后对设备检查情况：<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　1、由于机组转速高达3699转／分时，危急遮断器两个心杆罩帽全部脱出，丝扣撸坏，心杆与罩帽销子被剪断，其中l号，心杆在销孔最小截面处断开，在反作用力作用下，2号舌板将其上部的限位板在90度弯曲处撞击裂开上移，使其失去对2号舌板的限位作用。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　2、 &nbsp;<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;揭开低压缸检查，除发现20级有3处、25级有8处、叶片松拉筋有开焊外，还有两处叶片镶焊的司太立合金在距非叶片顶部30mm处裂断，其它部位均未见异常。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　3、 &nbsp;<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;对一、二、三段抽汽逆止门进行了汽密性试验，结果一、二段严密，三段抽汽逆止门前疏水管热，说明有漏汽现象。经对全部六段抽汽逆止门解体检查，各门密封面接触无断开处，无贯穿沟痕，深坑等。各门全行程活动自由，无卡涩。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　4、 &nbsp;<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;对自动主汽门进行解体检查，予启阀和主阀行程正常，无卡涩，主阀与门座接触无明显断开处和贯穿性沟痕，但有一长50mm锈迹与阀座位置相对应。该门主阀经多次研磨处理，其表现硬层基本消失，其密封接触面较宽，为7～8mm，在主汽门滤网前，有较多细铁渣和氧化皮性质的杂物。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　5、 &nbsp;对调速汽门进行解体检查，发现1号阀密封面接触较好，2、3、4号阀密封面接触不好，有小的沟痕坑点等。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　6、 &nbsp;对发电机转子风扇叶片全部进行外观检查未见异常，抽取4个风叶进行探伤检查正常，转子端部固件未见松脱等异常现象。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　7、对主、副励磁机动静间隙检查均未见异常。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　8、 &nbsp;对各瓦检查除主油泵推力瓦间隙由0．12mm。增大到0．3mm和8号轴瓦下部有一块7X7mm钨金脱裂外．其它各瓦均未见异常。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　四、原因分析<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　1、发生这起事故的直接原因是热工人员在做处理。串轴保护缺陷的安全措施时，只断开了串轴保护跳主汽门回路，而没有断开串轴保护跳发电机回路中的压板，造成串轴保护误动作机组跳闸。<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;　　2． &nbsp;<br/>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;串轴保护误动后；尽管危急保安器已经动作，但由于主汽门和调速汽门不严密形成了正向进汽，使汽轮机转速继续飞升到3699转／分，是造成这次机组超速的主要原因。&nbsp;&nbsp;<br/><br/>