【Q&A Question 185】2018.07.09
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【Q&A Question 185】July 09, 2018: Why is it necessary to extract steam from the turbine seal? There is air inside the turbine before startup, and some steam also leaks from the shaft seal during the warm-up process; therefore, the shaft seal condenser and ejector should be started first before beginning operation. (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. The APP short-video skills competition has started! https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1951670
The shaft seal at the low-pressure cylinder end prevents steam from the high-pressure side from leaking out of the cylinder, while its function is to prevent air from entering the low-pressure cylinder and causing a drop in vacuum.
Prevent steam from escaping outside the equipment body and from entering the lubrication system； Generally, back-pressure steam turbines use steam seal extractors, while condensing steam turbines are sealed with shaft seal steam.
Before starting, there is air inside the turbine; during the warming-up process, some steam also leaks from the shaft seal. Therefore, the shaft seal condenser and ejector should be started first before beginning operation
There is air inside the turbine before startup, and some steam also leaks from the shaft seal during the warm-up process; therefore, the shaft seal condenser and ejector should be started first before beginning operation.
In back-pressure turbines, due to the high exhaust pressure, if the steam seal extractor and steam seal cooler are not activated first before starting up, a large amount of steam will leak out of the turbine through the shaft ends. Additionally, some of this steam will enter the bearing lubricant, causing the lubricant to become water-emulsified. Therefore, it is necessary to first enable steam seal evacuation to create a certain degree of vacuum, thereby drawing out the steam and cooling it into condensed water.
Prevent steam from escaping outside the equipment body and from entering the lubrication system； Generally, back-pressure steam turbines use steam seal extractors, while condensing steam turbines employ shaft seal steam for sealing
Before starting the turbine, there is air inside it, and the pressure inside the turbine is roughly equal to the atmospheric pressure. If vacuuming is not performed, the air cannot be removed, and as a result the exhaust pressure increases. In such a situation, to get the turbine to rotate, the amount of steam supplied to it must be increased significantly in order to overcome the friction and inertial forces of the compressor bearings; this results in large stress forces being applied to the blades. After the turbine starts rotating, the heat transfer rate decreases due to the presence of air, the exhaust pressure rises, which may cause damage to the internal components. Therefore, the steam seal extractor must be turned on before starting the backpressure turbine.
Before starting, there is air inside the turbine; during the warming-up process, some steam also leaks from the shaft seal. Therefore, the shaft seal condenser and ejector should be started first before beginning operation
There is air inside the turbine before startup, and some steam also leaks from the shaft seal during the warm-up process; therefore, it should be done before starting