| 摘要 |
<p>A revolution speed control method in a gas turbine shutdown process for reducing a stress on a moving vane. (a) A load is maintained at a 4/4 load up to time t1 at which a fuel begins to be throttled, is decreased to be set to a 0/4 load at time t2, is maintained at no load up to time t3 at which the fuel is shutoff, and is further decreased thereafter. (b) A revolution speed is maintained at a rated level up to time t2 at which a 0/4 load is reached, is decreased starting at time t2, and is controlled to decrease to about 60 % of the rated level at time t3. (c) Metal temperatures at a point A of a platform and a point B of the moving vane, which are slightly different from each other, are kept constant up to time t1, decrease somewhat between time t2 and time t3, and give a maximum temperature difference Δt at time t4 in the course of decrease after time t3. (d) A stress on a moving vane decreases between time t1, and time t3, peaks at a maximum level at time t4 due to a centrifugal force and a thermal stress, but is relieved thereafter because of a centrifugal force that has decreased according to a revolution speed decrease to 60 % between t2 and t3, the temperature decreases and a resulting maximum stress decrease.</p> |
