tapping of compressed air from GT

B

Thread Starter

barin

I have two mark-V gas turbine.

There is 6kg/cm2 compressed utility air system in my plant.
My gas turbine CPD stays normally at 7-10 kg/cm2.
Sometimes due to maintenance activity my compressed air system fails to meet the load.

I am planing to tap a 2inch line at gas turbine main compressor discharge line with a flow controller.
I need max 1000 m3/hr.
And if necessary i can manage with lesser flow.

Is there any problem....??

Suggestions are requested.
 
This is, or used to be, done fairly frequently. HOWEVER, you need to realize that any air you take from the axial compressor discharge will mean that much less air for combustion and cooling and dilution. Meaning that the performance of the unit will decrease as the air flow decreases.

You must also have a check-valve or some kind of reverse flow preventer on the line.

 
> This is, or used to be, done fairly frequently. HOWEVER, you need to realize
> that any air you take from the axial compressor discharge will mean that much

----snip ----

> You must also have a check-valve or some kind of reverse flow preventer on the line.

Is there any ready made scheme available...??
if yes plz help.
 
>Is there any ready made scheme
>available...??
>if yes plz help.

None that I'm aware of. Each scheme was engineered for the desired parameters.
 
Another thing to keep in mind, is a good isolation valve. During water wash cycles, you won't want the water wash to contaminate your air system.
 
That is a good point about the isolation valve being closed during Off-Line Water Washing (or On-line Water Washing, for that matter).

Another thing to mention is that many times axial compressor discharge air is fairly "damp" due to ambient conditions or the use of evaporative cooling of the inlet air. A good means of drying the air is required before it's admitted to a proper instrument air system, which should be very dry and free of moisture.

I do recall one site that bypassed the dryer on the extraction air line and in the process damaged some instruments (mostly pneumatic actuators) with wet air. The Cogen Department wasn't aware of the requirements of the mill they were supplying instrument air to (along with steam) and it was very costly as the mill had to be shut down several times to replace the actuators as they failed.

In fact it was so costly the mill stopped taking any instrument air from the Cogen Department, upgrading their air compressors instead.
 
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