Cold start of steam turbine
Thread Content
During the cold start of a turbine, it enters a warm-up mode after starting up; how do the control valves function at this time? Is the opening degree of the main gate valve through which steam enters the turbine usually very small?
The main air valve should be fully open, and the regulating air valve should automatically adjust its opening degree according to the desired speed.
Check whether the warm-up mode is full arc warm-up or half arc warm-up
Is it because of the regulating valve – can’t it be adjusted during warm-up?
What do these two terms mean, and what is their relationship to the manual gate valve in the steam pipeline?
Warm-up generally involves getting the turbine to rotate. In back-pressure turbines, the amount of steam supplied is controlled through the inlet valve in order to carry out warm-up at a low speed. In large condensing turbines, the main steam valve and the throttle valve are opened fully, while an emergency shut-off valve (with a handwheel) is used to control the amount of steam entering the turbine, thereby enabling warm-up at a low speed; this is what is known as semi-circular warm-up, and Mitsubishi Elliott uses this method. Another method involves keeping the steam main valve fully open and the shut-off valve also fully open, while adjusting the speed of the governor valve to carry out slow-speed warming up; this is known as full-arc warming up, and Hangzhou Steam Siemens uses this approach.
First of all, is the warm-up mode you mentioned in automatic mode or manually controlled? The opening degree of the control valve depends mainly on parameters such as steam flow rate, temperature, and pressure, as well as the speed of rotation. When starting the engine set for warming up, a bypass is sufficient in some cases. As the rotation speed increases, the amount of air intake also increases. Generally, the opening degree of control valves should not exceed 10%
It is generally controlled by adjusting the air valve. When entering the warm-up mode, Mode 1 and Mode 2 correspond to 1000 revolutions per minute and 2000 revolutions per minute respectively; as the rotational speed increases, the air valve gradually opens wider, thereby increasing the amount of air intake