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How effective compressor water wash, what major factor effect to gas turbine gas performance.
akulahtu [at] ymail.com
akulahtu [at] ymail.com
K
Kashif
Valuable information are available in GE o&m manuals regarding water washing. Water washing affect in performance depends upon operating environments. Two types of water washing process are applied by GE
Online
offline
Online washing does not make much difference on performance. Any waY IGV and first few stages becomes little clean and improve performance of compressor little bit.
Off line washing is much affective, Whole compressor as well as turbine is become clean.
difference in MW before and after washing are very much clear, interval depends upon site conditions
Online
offline
Online washing does not make much difference on performance. Any waY IGV and first few stages becomes little clean and improve performance of compressor little bit.
Off line washing is much affective, Whole compressor as well as turbine is become clean.
difference in MW before and after washing are very much clear, interval depends upon site conditions
Performance is a function of a lot of things, not just filter dp and compressor cleanliness.
How long since the last maintenance inspection?
How long has it been since the CPD transmitter was calibrated?
If the unit has more than one CPD transmitter (96CD-n), are they both indicating relatively the same pressure or are they reading differently, and if so, by how much?
Were the transmitter sensing lines closed during the washing and then opened after the rinse was complete? Is it possible there is moisture in the CPD transmitter sensing lines?
How much has the CPD dropped for the same ambient temperature before
the wash?
Has the ambient changed suddenly?
Have the exhaust temperature spreads changed (increased) since the washing? Or have they decreased?
Has anything else changed since immediately before the wash until now?
What fuel is being burned?
Is the frequency stable?
Does the unit have evaporative coolers?
Does the unit have water- or steam injection? If so, has the injection ratio changed from before the washing (at the same load and fuel flow-rate)?
Is it humid and/or dusty at the location? Has it gotten more humid or more dusty since the washing?
As Kashif says, an off-line water wash is more effective than most on-line water washes. But, if a unit isn't rinsed properly and/or too much detergent is used (and too much is usually used) then the compressor can foul quickly again. The best off-line water washes start with an inspection of the inlet (IGVs, bellmouth, and first couple of of the axial compressor) and also end with an inspection of the same to determine if the wash was as complete as desired.
And, because too much detergent is usually used the rinses can take a LONG time and a LOT of water, and people don't always rinse as thoroughly as they should, especially if they need to get the unit back on line quickly.
There are a lot of factors that affect the efficiency and performance of a combustion turbine, and on off-line water wash is most effective when done properly, which includes proper rinsing and an inspection to determine if the compressor was cleaned to the desired condition.
How long since the last maintenance inspection?
How long has it been since the CPD transmitter was calibrated?
If the unit has more than one CPD transmitter (96CD-n), are they both indicating relatively the same pressure or are they reading differently, and if so, by how much?
Were the transmitter sensing lines closed during the washing and then opened after the rinse was complete? Is it possible there is moisture in the CPD transmitter sensing lines?
How much has the CPD dropped for the same ambient temperature before
the wash?
Has the ambient changed suddenly?
Have the exhaust temperature spreads changed (increased) since the washing? Or have they decreased?
Has anything else changed since immediately before the wash until now?
What fuel is being burned?
Is the frequency stable?
Does the unit have evaporative coolers?
Does the unit have water- or steam injection? If so, has the injection ratio changed from before the washing (at the same load and fuel flow-rate)?
Is it humid and/or dusty at the location? Has it gotten more humid or more dusty since the washing?
As Kashif says, an off-line water wash is more effective than most on-line water washes. But, if a unit isn't rinsed properly and/or too much detergent is used (and too much is usually used) then the compressor can foul quickly again. The best off-line water washes start with an inspection of the inlet (IGVs, bellmouth, and first couple of of the axial compressor) and also end with an inspection of the same to determine if the wash was as complete as desired.
And, because too much detergent is usually used the rinses can take a LONG time and a LOT of water, and people don't always rinse as thoroughly as they should, especially if they need to get the unit back on line quickly.
There are a lot of factors that affect the efficiency and performance of a combustion turbine, and on off-line water wash is most effective when done properly, which includes proper rinsing and an inspection to determine if the compressor was cleaned to the desired condition.
