Hi CSA and other senior experts,

As MWI (Modified Webbo Index) was more and more mentioned, I have questions about MWI. Below is the MWI definition:

MWI = LHV/sqrt(Tg*SG)

So what is the physical meaning of MWI?

1)I was told that MWI should be maintained in the range of 5%.
so why? What will MWI affect?

2)How is MWI be maintained in the range of 5%?
Are LHV, Tg, SG measured to calculate the realtime MWI and controlled?

3)I find that the Valve stroke are modified by MWI.
So what is the point? The Control system will control automatically if gas fuel mass flow is not enough. why to modify the fuel stroke by MWI?

Thanks in advance.
Neo
[email protected]

 

https://en.wikipedia.org/wiki/Wobbe_index

There are also commercial considerations where MWI would be useful.

 

Hi

Answering your questions:

1) MWI maintained in the range of 5%

The allowable MWI range is established to ensure that required fuel nozzle pressure ratios are maintained during all combustion/turbine modes of operation. When multiple gas fuels are supplied and/or if variable fuel temperatures result in a MWI that exceed the 5% limitation

2) How is MWI be maintained in the range of 5%

The gas chromatograph analyzes the composition of continuous natural gas, if the value is <42.66 (in our turbine), the combustion system performs a mode change 6.3 to 6.2 (9FB). We implemented a new control Tª SP Performance Heater to minimize the effects to a loss of quality of Natural Gas, to a decrease of Wobbe index VFGW TG <42.66 2 SP Tª the changes Performance Heater 185 ° C to 180 ° C (356F).

For more information query / search GEI 41040