| 摘要 |
<p>Stress occurring in moving blade in gas turbine stopping process is decreased. Where time t1 is load decrease start or fuel throttling start, time t2 is no load operation start, time t3 is fuel shut-off and time t4 is time of largest stress, (a) 4/4 load until t1 decreases gradually to 0/4 load at t2 to be kept until t3 and then decreases further, (b) rotational speed is rated one until t2 to be then controlled to be decreased gradually to about 60% of the rated rotational speed at t3, (c) metal temperature with differential temperature between moving blade point A and platform point B is constant until t1 to be then decreased slightly between t1 and t2 and between t2 and t3, and differential temperature DELTA t, which is largest after t3, occurs at t4, and (d) stress occurring in moving blade, while decreasing between t1 and t3, becomes largest at t4 by effect of centrifugal force and thermal stress, but as the rotational speed is decreased to about 60% of the rated rotational speed at t3 and the metal temperature is also decreased as compared with prior art, influence of centrifugal force and differential temperature is decreased, thereby stress occurring in the moving blade is mitigated. <IMAGE></p> |
