Method of starting up turbines

Abstract

Abstract At the point of time to when the turbine speed has come up to a first speed N 1 , a thermal stress expected in the turbine when the speed is increased to a second speed N 2 at a rate α 1 is presumed. Thermal stress σ s (t) -σ sT1 at the point of time t o1 for commencing acceleration to the second speed N 2 is then obtained, which point of time t o1 would never cause the maximum value of the presumed thermal stress to exceed a predetermined limit σ sl of the thermal stress when the turbine speed is increased at that rate. Then, a length of time T w1 , referred to as a warming time, is determined which is required for the thermal stress σ s (t) to decrease to the level of (σ s (t) -σ sT1 ) when the warming is continued after the point of time t o . Subsequently, a length of time (N 2 -N 1 )/α 1 required for increasing the turbine speed from N 1 to N 2 at the rate α 1 is calculated. The sum of the warming time T w and the time (N 2 - N 1 )/α 1 required for acceleration is calculated. The lengths of time for starting T 1 , T 2 , T 3 are found for each of the acceleration rates α 1 , α 2 , α 3 in speed. The acceleration of the turbine is commenced at the time and with the rate which in combination provide the smallest sum T of time.

Inventors

• 👤 Yoshio Sato
• 👤 Mistuyo Nishikawa

Bibliographic Details