On Friday, 14 January 2000 09:00:00 UTC+1, Steve Hunter wrote:
The ABB system is not used by other manufacturers e.g. GE as it is possible that if you have a trash screen or other element inside the gas turbine
inlet duct then localized icing may occur there which would not be detected by inspecting the IGV's. If it was serious enough, a small "chunk" of ice could break off and cause damage to the compressor blading.
If your climate has a large variation in humidity at low temperatures (i.e. northern Canada), an alternative system uses humidity and temperature to determine if icing is possible and only turns on the anti-icing if needed.
In your case, I would suggest that icing is not possible at +7 deg C and
70% humidity - perhaps you could investigate a variable humidity input
(i.e. turn icing on if -7 deg C and 70% RH at the low end and +7 deg C, 95% RH at the high end and a linear interpolation between). This system is in operation on some GE gas turbine (mostly Frame 6B's).
I don't think that the +7 deg C limit is necessarily too high - you have to take into account the fact that air in the inlet system is operating below atmospheric pressure (and therefore any water vapour freezes at greater
than 0 deg C) and the velocity of the air flowing past obstructions can
have a local effect.
An alternative (and more efficient) method of anti-icing for CCGT & Cogen plants which I have seen in operation on a Siemens V64.3A in Germany is to install a heating coil in the gas turbine inlet and pass warm condensate (typically 25-35 deg C) through the coil as needed to raise the temperature of the air entering the gas turbine inlet. A limitation of this system is that, unless you have auxiliary boilers, you must use a conventional system to protect the gas turbine during cold weather startup as the CCGT plant
will typically startup after the gas turbine.
I believe there are a number of inlet filter manufacturers who offer 3rd party aftermarket anti-icing systems - perhaps you could try these
companies of your gas turbine manufacturer doesn't give you any help?
Hope this helps
Steve Hunter
YGYang wrote in message <071bb362.7868c684@usw-ex0101-005.remarq.com>...
I am operating 150MW gas turbines, a part of combined Cycle power plant. >During the winter
We extract some hot air from the last stage of the compressor and
supply it into the Air inlet to prevent 'inlet icing'.
And it always causes slight of efficiecy decrease and the output down.
(I hate it.)
'Icing Alarm' is on by the turbien management system at the condition
of Inlet Air Temp from -7C(19F) to 7C(45F) and the relative humidity
more than 70%. and when the alarm is on, we have the Anti-icing System >working.
I think that the Icing Alarm condition mentioned above scopes too wide >and we operate Anti-icing system unnecessarily sometimes.
When I look some other Gas turbines under same weather condition, they >run well without cosidering Anti-icing System.
I beg your wistom and experiences about this problem. >--------------------------------------------------------------
1. Why does Inlet Icing in the gas turbine prevented?
( Does the icing damage the compressor blade? ) >-------------------------------------------------------------
2. What is reasonable Temp and humidity range to run the Anti-icing >system.
-------------------------------------------------------------
3. Is there any other way I don't use the Anti-icing System? >-------------------------------------------------------------
4. What do you think the differeces between my gas turbine and those >which don't use Anti icing System? >--------------------------------------------------------------
Pease give whatever it is .
Thanks your concerns!
* Sent from RemarQ http://www.remarq.com The Internet's Discussion
Network
*
The fastest and easiest way to search and participate in Usenet - Free!
Hello Gents,
Thank you Steve for your valuable feedback.
Could you please share with us your experience if the anit-icing is provided with air pulse cleaning to clean the pre-filter in case of ice formation (frost accumulation).
I mean is anti-icing system is enough without air pulsing system?
I agree with you that anti-icing should be start under precised control system with ambient air set point +4 C. GE provides anti-icing with two ways , first is hot air from turbine the second is electrical coil or another heating medium.
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)