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قديم 03-26-2011, 12:33 PM
الصورة الرمزية Khaled Hamza
Khaled Hamza Khaled Hamza غير متواجد حالياً
عضو فعال
 
تاريخ التسجيل: Aug 2010
الدولة: Egypt
المشاركات: 68
معدل تقييم المستوى: 14
Khaled Hamza is on a distinguished road
Lightbulb C**DENSER – AIR EXTRACTI** EQUIPMENT ( 1 Of 3 )

C**DENSER – AIR EXTRACTI** EQUIPMENT

- Turbines are designed for a particular operating c**diti**s like steam inlet pressure, steam inlet temperature and turbine exhaust pressure/ exhaust vacuum, which affects the performance of the turbines in a significant way. Variati**s in these parameters affect the steam c**sumpti** in the turbines and also the turbine efficiency. Theoretical turbine efficiency is calculated as work d**e by the turbine to the heat supplied to generate the steam.
- Higher exhaust pressure/ lower vacuum, increases the steam c**sumpti** in the turbine, keeping all other operating parameters c**stant. Exhaust pressure lower than the specified will reduce the steam c**sumpti** and improves the turbine efficiency. Similarly exhaust vacuum lower than the specified, will lower the turbine efficiency and reduces the steam c**sumpti**.
- The air extracti** EQUIPMENT must be capable of meeting two c**diti**s; **e met during normal operati**, the other when raising vacuum ** the turbo-generator unit.
- When raising vacuum the air extracti** equipment must deal rapidly with a large quantity of air and sufficient capacity must be installed to reduce pressure quickly in the C**DENSER to a level which allows the turbine to be started. The last row blades of a 500 MW turbine will overheat if they run at speed and at low load in a poor vacuum. Thus, a vacuum of 20 in.Hg must be obtained before steam is admitted to the turbine and a vacuum of 26 in.Hg for full speed. It is important that the time taken to bring a turbo-generator ** load shall not be increased by sufficient air extracti** capacity.
- Under normal operating c**diti**s the quantity of air to be exhausted is lower. It c**sists of air leakage into the c**denser via flanges and glands and also of inc**densable gases that are present in the steam exhausting from the turbine. Air and inc**densable must be removed from the c**denser as their presence in any quantity impairs the heat transfer capability of the c**denser and hence its performance. C**versely, excessive air extracti** capacity should not be run, as this involves unnecessary running costs and also results in the extracti** of an unwanted quantity of water vapor from the c**denser steam space.




“We will talk about the equipment for the extracti** in the 2 upcoming articles”


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