IS IBH open in low ambient or no in GE frame 9e gas turbine .

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Deleted member 3303

last week our ambient tempreture -13 celcius and 8fahrenhite, but ibh no open , what we have to do to safe turbine.
I am operating GE frame 9e gas turbine , we have DLN 1.0 .
Normally I saw GE gas turbine generating MW 128 in winter .
Last week ambient of our region -13 Celsius and humidity 99%.

I am little reservation regarding , is ibh open during low ambient or no .

I already check logic mark6e there is no any logic of ibh opening in low MW .

last maximum MW 136 . First time I saw in my experience

Deleted member 3303

dear CSA , i alreaady read your all discuusion and as far as i understand ibh only open during igv partially open , like in our gas turbine after synch ibh control v/v open and near 90mw ibh close .

but just clear me is any condition ibh open in low ambient ?
in which condition we have icing hazardous?
we have to much snow fall during these days, is snow fall and negative tempreture we have any actions ?
Irfan ahmed qureshi,

Some GE-design heavy duty gas turbine control systems use the IBH system for Anti-icing protection. If you have read some of my responses about IBH you know I believe it is a poorly named system for the purpose it serves--which is to protect the axial compressor from damage caused when the IGVs are closed below the typical minimum angle while operating at rated speed. This is not to protect against icing of the IGVs when ambient temperature is low and relative humidity is high (which is what anti-icing protection is for).

I believe the confusion is because, first, the name (Inlet Bleed Heat) implies the function of the system is to heat the axial compressor inlet air, when what it really does is reduce air flow through the axial compressor by recirculating a portion of the axial compressor discharge air back to the axial compressor inlet, which helps to reduce air density at the same it reduces back-pressure on the compressor thus protecting the compressor. (It's a lot more complicated than that, but basically that's what IBH does). This is necessary regardless of ambient temperature or -humidity. IGVs are typically closed below the minimum operating angle in order to allow the turbine to achieve Pre-mix Steady State operation at a lower load than would otherwise be possible OR to remain in Pre-mix Steady State at loads lower than would otherwise be possible. And that's when IBH is required and provided. And, again, it has nothing to do with ambient temperature or humidity.

Second, when a unit is configured with anti-icing protection it uses the same system of recirculating a portion of the axial compressor discharge air back to the axial compressor inlet--but the purpose in this case is to prevent the formation of ice on the IGVs when the unit is operating at low ambient temperatures AND high ambient humidity.

MANY people mistakenly believe that IBH is ALWAYS used for both functions--but that is untrue. About the only time GE recommends anti-icing protection for heavy duty gas turbines is when there is an un-natural source of humidity which may be drawn into the axial compressor when the ambient temperature is low. (Un-natural sources of humidity are cooling water tower plumes, or heavy nearby lake or ocean fog.) In this case if the unit uses IBH for DLN combustors then the same extraction system, control valve and manifold will be used to prevent ice formation on the IGV when operating at low ambient temperatures AND high high humidity--which is not the same as protecting the axial compressor when the IGVs are closed below the typical minimum operating for the compressor when running at rated speed.

I am not 100% clear about precisely what you are asking, but it seems to be that you are concerned about protecting the IGVs from icing because of the extremely low ambient temperatures being experienced at the site. Unless the snow is melting rapidly and causing fog to form (because there is little or no wind) which is being drawn into the axial compressor inlet there is probably not a problem. (And if this is happening then it's also likely the inlet air filters are also developing ice.)

I'm sure I'm approaching if not exceeding the 1500 character limit.... (AAARRRGGGHHH!!!)

Hope this helps! If not, please try to clarify the issue for me.

Deleted member 3303

Thanks a lot CSA , your guidance always helpful for all .

CSA , my concern as a control room operator, is we have any action when ambient low ?

1: like one of my friend told me decrese load till IBH open , it’s means when ambient low put machine on part load .

CSA , my another concern generator MW 136 , it’s no effect on health of generator ?

2: like as a operator I monitor winding temperature of generator and all parameters is normal , so it’s means high generation MW no any issue for a life of generator , because in document I read frame 9e machine design for 125 MW at full efficiency .
Irfan ahmed qureshi,

As a control room operator you should have SOPs: Standard Operating Procedures. These should be mostly site-specific documents that describe what the Operations Managers and Plant Manager and Owners have decided are the proper operating procedures for the equipment, and what responses operators should take in the event of non-standard conditions. (Yes; it's impossible to cover all the possible conditions, but this is one that should normally be covered: low ambient temperatures, combined with possible high ambient humidity).

IF the compressor inlet temperature is low (and it doesn't even have to be below freezing for ice to form on the IGVs!) AND the ambient humidity is high then it's also likely that the turbine inlet air filters are getting ice build-up, which is also increasing the inlet air filter differential above normal. To my mind, reducing load until the IGVs close sufficiently to cause IBH to be enabled is making the problem worse by increasing the pressure drop across the IGVs which increases the temperature drop which means ice will form faster. Now that may not be the actual case, but it's how I envision things happening with the basic temperature/pressure relationships. If the inlet temperature is low (say 2- or 3 deg C), AND the inlet humidity is high, then when the IGVs are not open very much the pressure drop across them is higher which depresses the air temperature which can cause icing. If the unit doesn't have the anti-icing function and load is reduced to enable IBH, then the IGVs are going to close so something close to minimum operating angle--or lower--and that's not ideal, in my personal opinion. My personal opinion may, or may not, match what the Operations Manager, or the Plant Manager, or the Plant Engineer, or the Plant Owner wants the plant to be operated.

Again, this is where the Operations Managers and Plant Managers and Plant Owners should be asked what to do and how to respond. Because, you are right--to get IBH to turn on, the load has to be reduced. And, MANY Plant Managers and their Operations Managers just want to make as much power as possible all the time to keep the revenue watt-hour meter turning as fast as possible. And, when units WITH anti-icing actually get into the conditions where anti-icing is automatically enabled and power output starts decreasing, well, Plant Managers and Operations Managers start calling GE and screaming, "Something is wrong with the Mark*!!! It's limiting my power output!!!" They want the protection, but they don't understand it comes at a cost--and they want the bonuses they are making when the power output is up when the ambient temperature is low. In other words, they want to have (keep) their cake, and they want to eat it, too. And, the cake won't last (won't keep for long) if it's eaten.

For your second question, turbine-generators are rated (power output) based on the ability of the TURBINE to produce power. If you look at the turbine nameplate and the generator nameplate, you will see the turbine nameplate is almost ALWAYS less than the generator nameplate. Why? Because, when the ambient gets low the turbine power output will increase--which will cause the generator power output to increase. If the turbine control system were programmed to limit the turbine power output because the generator was at its rating then the owner would be possibly losing money. (In fact, some turbine control systems in some ambients ARE limited when the ambient temperature is very low to protect the generator from overheating. Some are also limited by the strength of the load coupling (between the turbine and the generator) which may not even be capable of transmitting enough power to reach the generator nameplate.)

You need to be looking at what GE typically calls the 'Reactive Capability Curve' to determine if the generator is being operated within its limits when the turbine is producing high power when the ambient temperature is very low. You are correct to be monitoring the generator stator temperatures and armed with that information you should be able to use the Reactive Capability Curve to ensure you are not exceeding the generator's ability to cool itself when it's producing a lot of power because the turbine is producing a lot of power. (Sometimes people will refer to the same curve as the "D-curve" because it is shaped like a capital 'D'. Other generator manufacturers have their own terminology, but the all produce these "curves" (graphs; charts) which are used by operators to ensure the generators are being operated safely.

One thing to remember is that when the generator is producing LOTS of stator amperes (and therefore LOTS of watts) usually the excitation power being applied to the generator rotor is also very high. There usually isn't a sensor (or sensors) on the generator rotor to monitor rotor temperature, but sometimes the excitation system (the "AVR") can calculate the rotor temperature (a very crude calculation, usually). If so, this should be factored into the assessment of generator condition during high power output. (The Reactive Capability Curve, or D-curve, usually has this factored in--but sometimes, if the grid voltage is very high it's not properly taken into account.)

Again, SOPs (Standard Operating Procedures) should be available for these kinds of conditions. If they don't specifically address this particular condition (because it wasn't properly anticipated) it should be possible to ask for guidance, and to get the SOPs (which EVERY plant should have in this day and age!) modified to include the plant's desired practices. (SOPs are NEVER static documents--they should be constantly reviewed and modified as conditions change (turbines are upgraded; HRSGs are upgraded; cooling water systems are upgraded; new equipment is added; new ambient conditions are experienced. Just remember, climate change is a hoax. (NOT!))

Hope this helps!

Deleted member 3303

Thanks a lot CSA ,
Your guidance to others is really appreciates
God bless you always ,you are a good person who teach others and share knowledge with others

Wish you all the best always with healthy and joyful life.