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[R NESAMANI]

Dear all, I am working with one natural gas pipeline system.
We supply gas to powerplant. Customer needs at less than 34 Kg/cm2.
Our P/L press. is 70, using PCV, we reduce the pr. from 70 to 34 kg/cm2.
During this we loss pr.energy...
1) Is there any technology to utilize this energy....?
2) Also due to Pr reduction temp also reduces, causing the moisture formation on the P/L.
How to avoid this. Also suggest the method to paint this moisture P/L.

[ankur2061]

Nesamani,

I don't see any problem in reducing the pressure from 70 to 34 kg/cm2. Sales gas pipeline network pressures are always much higher than the consumers connected to the sales gas network.

Pressure Reducing Stations using control valves are used at the various consumers connected to the sales gas network. Generally for very large pressure reductions two-stage pressure reduction is practiced where the pressure is reduced to an intermediate value in the first stage and then to the final value throught the second stage. This is to prevent noise and vibrations due to sonic velocity conditions when the pressure ratio i.e. downstream pressure divided by the upstream pressure is much lower than the critical prsssure ratio. For definition of critical pressure ratio refer the link below:

http://www.cheresour...h__1#entry58342

Energy can be recovered by reducing gas pressure from a higher value to a lower value by using a turboexpander which is a proven and established technology. But in most cases this cannot be justified economically since the amount of energy recovered is not substantial in comaprison to the investment and operating cost of the turboexpander. A detailed economic analysis needs to be done to justify providing a turboexpander for recovery of energy from pressure reduction. One major drawback in using turboexpanders is that the gas fed to the turboexpanders has to have very low moisture content, typically less than 1 ppm.

For corrosion prevention of the pipeline, cathodic protection and Polythene (PE) lining of the pipeline is often practiced. PE lining requires careful consideration of gas being free of solid particles.

Hope this helps.

Regards,
Ankur.

Edited by ankur2061, 02 May 2012 - 12:35 PM.