Is it possible to substitute one gaseous fuel for another?
In many industrial processes, different gaseous fuels may need to be used interchangeably. However, for such substitution to be possible, the combustion characteristics of the fuels must be similar.
Combustion equipment such as burners and furnaces are precisely designed for a specific type of fuel. Parameters such as fuel flow rate, combustion energy output, and the amount of air required for complete combustion are calibrated according to that fuel.
For this reason, changing the fuel often requires adjusting these parameters. In some cases, minor modifications or tuning of burners and nozzles may allow a different fuel to be used. However, in large industrial facilities with dozens or even hundreds of burners, adjusting each burner individually can be impractical.
In such situations, instead of modifying the combustion equipment, the fuel gas itself can be conditioned or blended to match the combustion characteristics of the original fuel.
What is the Wobbe Index?
Fuel substitution without modifying combustion equipment can be achieved by bringing the combustion characteristics of two fuels closer to each other. One of the most important parameters that indicates the combustion behavior and interchangeability of a gaseous fuel is the Wobbe Index, proposed by the Italian scientist Goffredo Wobbe.
The Wobbe Index is calculated by dividing the heating value of the fuel by the square root of its specific gravity.
Fuels that have the same or very similar Wobbe Index values can generally be used interchangeably in combustion systems without requiring equipment modifications. Under these conditions, approximately the same amount of energy is released using the same fuel flow and the same air supply, resulting in similar combustion performance.
Fuel Substitution Using LPG Air Mixing Systems
LPG Air Mixing Systems are used to generate Synthetic Natural Gas (SNG). By mixing LPG with air in precise ratios, the resulting gas can be adjusted to match the Wobbe Index and combustion characteristics of natural gas.
This allows industrial facilities to:
- use LPG as a backup fuel for natural gas systems
- maintain stable burner performance
- avoid costly modifications to existing combustion equipment
- ensure continuous production during natural gas interruptions
Learn more about LPG Air Mixing Systems used for SNG generation
