【Q&A Question 112】April 22, 2018
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【Q&A Question 112】April 22, 2018: Briefly explain what the coasting time of a turbine is What does the change in coasting time indicate? The coasting time of a turbine refers to the period from the moment the generator is disconnected and the automatic main steam valve and throttle valve are closed until the rotor comes to a complete stop; this time is known as the rotor’s coasting time. The curve that shows the relationship between the rotor’s coasting time and the decrease in speed is called the coasting curve. Changes in the coasting time indicate the following issues: ① A longer coasting time at high speeds suggests that there is leakage due to improper sealing of the main steam valve, control steam valves, or check valves in the extraction pipelines. ② If the coasting time is shorter than before, it indicates poor vacuum maintenance, changes in oil temperature, and friction in the mechanical components; this may be caused by deteriorating bearing performance or friction between the moving and stationary parts of the turbine. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) The validity period for this question is 48 hours; within those 48 hours, 10 wealth points are awarded for correct answers and 2 wealth points for incorrect answers ； If the response is given after 48 hours, the score is halved, regardless of whether it is correct or not ； 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. The APP short-video skill competition has started! https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1951670
Coasting time refers to the period during which, after the unit’s systems are shut down and its load is reduced as much as possible, the main steam valves and control valves close until the rotor comes to a complete stop. A longer coasting time indicates that there is leakage in the turbine’s main steam valves and control valves. Idle time decreases: the alignment of the unit worsens, there is friction in the mechanical components, and the quality of the lubricating oil deteriorates.
Coasting time refers to the period required during the shutdown process of a turbine, starting from the moment the main valve controlled by the emergency safety device is closed, until the rotor comes to a complete stop. This period is known as coasting time. Each turbine unit generally has a fairly precise range for this value; deviations from this range indicate changes in the internal structure of the unit, such as severe fouling on the blades, which can increase the coasting time. Alternatively, if the main valve does not close properly and steam leaks in, this too can lead to an increased coasting time. A too-short coasting time may be caused by the drain valves connecting the expansion tank to the cylinders not being closed properly, allowing steam to flow back into the cylinders. There are many factors that can affect the turbine’s coasting time, and it is necessary to analyze these factors in light of the actual situation
Coasting time refers to the period during which, after the unit’s systems are shut down and its load is reduced as much as possible, the main steam valves and control valves close until the rotor comes to a complete stop. A longer coasting time indicates that there is leakage in the turbine’s main steam valves and control valves. Idle time decreases: the alignment of the unit worsens, there is friction in the mechanical components, and the quality of the lubricating oil deteriorates.
The coasting time of a turbine refers to the period from the moment the generator is disconnected and the automatic main steam valve and throttle valve are closed until the rotor comes to a complete stop; this time is known as the rotor’s coasting time. The curve that shows the relationship between the rotor’s coasting time and the decrease in speed is called the coasting curve. Changes in the coasting time indicate the following issues: ① A longer coasting time at high speeds suggests that there is leakage due to improper sealing of the main steam valve, control steam valves, or check valves in the extraction pipelines. ② If the coasting time is shorter than before, it indicates improper maintenance of the vacuum level, changes in oil temperature, and friction in the mechanical components; this may be caused by deteriorating bearing performance or friction between the moving and stationary parts of the turbine
The coasting time of a turbine refers to the period from the moment the generator is disconnected and the automatic main steam valve as well as the throttle valve are closed until the rotor comes to a complete stop; this period is known as the rotor coasting time. Explanation of changes in idle time: 1. An increase in idle time at high speeds indicates that there is a leakage issue, possibly due to a loose main steam valve, a faulty speed control valve, or a leaky check valve in the oil extraction pipeline ； 2. If the idling time is shorter than before, it indicates improper vacuum maintenance, changes in oil temperature, and friction in the mechanical components; this may be caused by deteriorating bearing performance or friction between the moving and stationary parts of the turbine.
The coasting time of a turbine refers to the period from the moment the generator is disconnected and the automatic main steam valve and throttle valve are closed until the rotor comes to a complete stop; this time is known as the rotor’s coasting time. The curve that shows the relationship between the rotor’s coasting time and the decrease in speed is called the coasting curve. Changes in the coasting time indicate the following issues: ① A longer coasting time at high speeds suggests that there is leakage due to improper sealing of the main steam valve, control steam valves, or check valves in the extraction pipelines. ② If the coasting time is shorter than before, it indicates poor vacuum maintenance, changes in oil temperature, and friction in the mechanical components; this may be caused by deteriorating bearing performance or friction between the moving and stationary parts of the turbine.
Coasting time refers to the time required during the shutdown process of a turbine, starting from the moment the main valve controlled by the emergency safety device is closed, until the rotor comes to a complete stop. This time is known as coasting time. Generally, each turbine unit has a fairly precise range for this value; if it exceeds this range, it indicates that there have been changes in the internal structure of the turbine, such as its blades. The answer is from Baidu; I’m using what I’ve just learned. . .
Coasting time refers to the period during which, after the unit’s systems are shut down and its load is reduced as much as possible, the main steam valves and control valves close until the rotor comes to a complete stop. A longer coasting time indicates that there is leakage in the turbine’s main steam valves and control valves. Idle time decreases: the alignment of the unit worsens, there is friction in the mechanical components, and the quality of the lubricating oil deteriorates.
The coasting time of a turbine refers to the period from the moment the generator is disconnected and the automatic main steam valve as well as the throttle valve are closed, until the rotor comes to a complete stop; this period is known as the rotor coasting time
The time period from the disconnection of the generator, the closing of the automatic main steam valve and the speed control valve, until the rotor comes to a complete stop is known as the rotor coastdown time. There is generally a fairly precise range for the coasting time for each unit; exceeding this range indicates that there have been changes in the internal structure of the unit, such as its blades. For example, severe scaling on the blades will increase the idle time, or if the main valve does not close properly and steam leaks in, this too can lead to an increased idle time. If the idle time is too short, it may be due to the steam trap from the expansion tank to the cylinder not being closed properly, allowing steam to flow back into the cylinder.