【Q&A Question 248】2018.09.11
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【Q&A Question 248】September 11, 2018: Briefly explain why it is necessary to maintain the back pressure constant when shutting down a back-pressure steam turbine. When shutting down such a turbine, the steam flow is reduced by adjusting the control valves and main steam valves through the speed control system, which in turn causes the rotational speed to decrease gradually. Since the load on the turbine is low at this time, if the back pressure also decreases, the speed of the turbine will not drop; in fact, it may even increase. This is unfavorable for a stable shutdown, which is why back-pressure turbines maintain a constant back pressure during shutdown. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) Correct: 3 wealth, Incorrect: 1 wealth ； Mass posting of posts – rated based on the lowest score ； Replies that are unrelated to the answer are considered spam and will be deleted immediately. For management purposes, if you need to view content from a few days ago, please go to https://bbs.hcbbs.com/home.php?mod=space&uid=3862647&do=thread&view=me&from=space through the summary post below
When a back-pressure steam turbine is shut down, the speed is reduced gradually by lowering the amount of steam supplied, through the control system that operates the control valves. Since the load on the turbine is low at this time, if the back pressure also decreases, the speed of the turbine will not drop; in fact, it may even increase. This is unfavorable for a stable shutdown, which is why back-pressure turbines maintain a constant back pressure during shutdown.
If the back pressure is unstable, it can cause fluctuations in the turbine’s speed, affecting its ability to operate at reduced speeds; such fluctuations may also lead to damage to components such as seals.
When a back-pressure steam turbine is shut down, the speed is reduced gradually by lowering the amount of steam supplied, through the control system that operates the control valves. Since the load on the turbine is low at this time, if the back pressure also decreases, the speed of the turbine will not drop; in fact, it may even increase. This is unfavorable for a stable shutdown, which is why back-pressure turbines maintain a constant back pressure during shutdown.
When a back-pressure steam turbine is shut down, the speed is reduced gradually by adjusting the control valve through the speed control system, thereby decreasing the amount of steam supplied. Since the unit load is low at this time, if the back pressure also decreases, the rotational speed of the turbine will not drop; in fact, it may even increase. Under such circumstances, a smooth shutdown is not feasible.
When a back-pressure steam turbine is shut down, the speed is reduced gradually by lowering the amount of steam supplied, through the control system that operates the control valves. Since the load on the turbine is low at this time, if the back pressure also decreases, the speed of the turbine will not drop; in fact, it may even increase. This is unfavorable for a stable shutdown, which is why back-pressure turbines maintain a constant back pressure during shutdown.
During shutdown of a back-pressure steam turbine, the speed is reduced gradually by adjusting the control valve and the main steam valve through the speed control system, thereby decreasing the amount of steam supplied. Since the load on the turbine is low at this time, if the back pressure also decreases, the speed of the turbine will not drop; in fact, it may even increase. This is unfavorable for a stable shutdown, which is why back-pressure turbines maintain a constant back pressure during shutdown.
This post was last edited by Blue Flame on 2018-9-11 at 15:21. Answer: When a back-pressure steam turbine is shut down, the speed control system is used to reduce the flow of steam by closing the control valves and the main steam valve, thereby gradually lowering the rotational speed. Since the load on the turbine is low at this time, if the back pressure also decreases, the speed of the turbine will not drop; in fact, it may even increase. This is unfavorable for a stable shutdown, which is why back-pressure turbines maintain a constant back pressure during shutdown.
When a back-pressure steam turbine is shut down, the speed is reduced gradually by lowering the amount of steam supplied, through the control system that operates the control valves. Since the load on the turbine is low at this time, if the back pressure also decreases, the speed of the turbine will not drop; in fact, it may even increase. This is unfavorable for a stable shutdown, which is why back-pressure turbines maintain a constant back pressure during shutdown.
When a back-pressure steam turbine is shut down, the speed is reduced gradually by lowering the amount of steam supplied, through the control system that operates the control valves. Since the load on the turbine is low at this time, if the back pressure also decreases, the speed of the turbine will not drop; in fact, it may even increase. This is unfavorable for a stable shutdown, which is why back-pressure turbines maintain a constant back pressure during shutdown.