Natural Gas Metering


Thread Starter

Instrument eng

Dear All

We have Combine cycle power plant. The fuel used is Natural Gas. I want to know some brief regarding Natural Gas Metering system like, AGA-3 Standard, AGA-8 standard, ISO-6976, etc.

Here which base pressure, Base temperature required for flow metering? and what happen if we change base temperature of metering system and gas Chromatograph.

How NCV, GCV calculated?

Is there any calculator available for natural gas flow?

Please let me know.
The basic flowmeters can be orifice, turbine or PD types which measure volumetric flows.

The choice of when and how to compensate for pressure and temperature variation depends on costs.

At a certain level the cost is such T&P (PTZ) compensation is preferred but for larger systems it becomes more cost effective to use gas density and even gas relative density (for quality; the wobbe index can be derived) i.e. with density you start to pay for the mass of gas more accurately than when using PTZ and beyond that the gas quality variations start to become sufficiently significant that relative density is an important measure. Relative density is more important if you suspect that the gas supply quality is at all suspect.

Commercial gas supplies are often quite well regulated but if your plant is operating on fuel gas from a refinery you may find the quality much more variable if it is essentially waste gas after they have stripped out some components for petrochem use.

The flow computers used will provide the option of which standard you use and what your flowmeter inputs are. I would suggest contacting the relevant sales offices for more information.
For more information on these systems I'd suggest looking at the Sarasota and Solartron gas density and gas relative density solutions. Sarasota is now part of Thermo and Solartron density is now part of Micromotion.