GT compressor inlet pressure

A

Thread Starter

ashiq

Dear friends

which factors effect the reading of compressor inlet pressure, normally the reading remains 22 mbar which now arrived to 09 mbar ... we have replaced the transmitter calibrated with range 0-30 mbar ..where -ve side impulse line is used and +ve side is open to atmosphere.

why the reading went low ..while it goes to 15 mbar only when air intake filter replaced

cheers
ashiq
 
ashiq,

Without a P&ID to understand where the pressure taps for the instrumentation is installed it's very difficult to comment on what's happening.

If you want to confirm a differential pressure reading, it's very simple. You can make a water-tube manometer and connect it in parallel with the transmitter.

Just use your preferred Internet search engine to find details about how to construct a water-tube manometer. All that's required is some plastic tubing, a board on which to mount the tubing, a scale (usually, I use a ruler or a piece of a broken tape measure), some water and some food coloring dye (any color-red, dark green, dark blue, any dark color), and a means of connecting the ends of the plastic tubing to the same pressure taps as are being used for the transmitter.

You can use this to confirm any differential pressure reading (small differential pressures, of course, though larger ones can be fashioned; I've seen some that were four or five meters tall used in extreme cases).

Many instrument shops I've been to have had water-tube manometers stashed away on shelving and didn't even know it (they have no electronic components are considered "old technology" and so most of the younger people don't want to deal with them...). They come with flourescent dye for the water (instead of food coloring). They can be very useful, even though they are "old tech" not new tech.

Again, have a look at the P&ID for this system, or, draw your own. If you do should be able to understand what is being measured and what the effects of changes, such as changing inlet air filters, will--or won't--have on the readings. Unless we can see the P&ID, we can't be of much more help.
 
Dear CSA

I will test the reading as per your advise and share the result.

P&ID shows only one impulse line coming from air intake duct for this measurement(MBA11CP004). while this impulse line is also used by compressor surge protection switch (MBA11CP001), where other impulse line is taken from compressor inlet.

Manual says:
Pressure Upstream of compressor
Pressure transducer MBA11CP004 measures the sub atmospheric pressure in the compressor intake duct.This pressure measurement in combination with the air temperature measurement upstream of compressor is used to determine the compressor mass flow.
 
ashiq,

The "air intake duct" of a Frame 9FA is very large.

If your friend said, "I can't read my watch when I put it on my arm," you would presume he meant the wrist area of his arm, but, he might be putting on the bicep area or in the fold of the elbow. Without seeing where, or without more information, you couldn't provide much help to your friend.

I don't recognize the device numbers/numbering scheme being used for the devices. I suspect the devices were "re-numbered" using some other scheme than GE typically used, for whatever reason (perhaps the original purchase required use of a different scheme than GE typically used; or the plant designer was required to incorporate the turbine field devices and instrumentation into a plant-wide scheme).

Only by looking at a P&ID could we determine for ourselves exactly where the sensing line is connected to the "air intake duct." Is it in the bellmouth? Is it above the air intake duct? If so, by what physical distance? Is it downstream of the inlet air filters but upstream of the trash screen and/or inlet silencers? Is it downstream of the inlet silencers but upstream of the inlet elbow?

While this particular value might be used as part of the calculation of mass flow, more information would be necessary than just the air temperature (bellmouth pressure drop, ambient pressure (outside the "air intake duct), etc.). Most gas turbine air flow monitoring/measuring equipment provided by GE includes ambient pressure sensor(s) (very often, redundant sensors are used), a static inlet pressure sensor, and a bellmouth inlet pressure (drop) sensor, along with air temperature, and in some cases, exhaust flow sensor(s), as well.
 
>ashiq,

THE INLET PRESSURE OF THE GAS TURBINES DOES NOT REMAIN THE SAME BUT IT VARIES ACCORDING TO THE FACTORS AND WEATHER CONDITIONS. FACTORS SUCH AS AIR INLET TEMPERATURE, HUMIDITY, AIR DENSITY ARE VERY IMPORTANT IN THIS REGARD. HAVE A TREND OF THESE FACTORS AND CHECK YOUR TURBINE INLET PRESSURE ACCORDINGLY. CHECK THE AIR INLET PRESSURE ON THE DUCT IF A SENSING POINT AVAILABLE.
 
G

Genset_Expert

I think the gas turbine Ashiq is referring to is Siemens V94.2.

I knew that from the KKS of the inlet pressure sensor.

I hope this will help.
 
Dear Ashiq

If Compressor inlet pressure is raised as per transmitter reading, what is its impact at Compressor discharge pressure? Any change in Compressor discharge pressure/Temperature observed?

Also you check the pulse line regarding any blockage, do the line flushing/blowing with air.

And what is the behaviour of climate conditions during this disturbed conditions any windy/dusty or rainy weather? and also check out against any manway/entrance gate regarding open state, etc.
 
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