The Combustion and Interchangeability of Natural Gas on Domestic Burners

Abstract

The burning characteristics of natural gas and the determination of its inter-changeability with liquefied petroleum gas on domestic burners are presented in this paper. Earlier studies had sought the correlation of heating values with specific gravities as a basis for determining the interchangeability of the gas. In this study, it is established that, additionally burning characteristics, which depend on chemical composition, must also be included to accurately predict the range of interchangeability achievable in a given situation. The Wobbe Number, combustion potential and yellow tip index are calculated for both liquefied petroleum gas (LPG) and various compositions representative of associated low-pressure and non-association high pressure natural gas. These were then graphically presented as area enclosed by lines representing limits of flash back, lifting and incomplete combustion. It is found that natural gas can be interchanged with LPG as substitute gas for domestic burners, without adjustment of the burner nozzle. The necessary condition for this is that the quality of combustion for the associated natural gas is enhanced when it is fed into the burner above the hydrocarbon and water dew points of the gas, and at twice the pressure at which bottled liquefied petroleum gas is usually supplied to the burners.

Keywords:  Natural gas, liquefied petroleum gas (LPG), burning characteristics, Wobbe Number, combustion potential and yellow tip index