A study on the interchangeability of biogas-LPG mixed gases with biogas and LPG qualities

Interchangeabilities of biogas (BG) and liquefied petroleum gas (LPG) mixed gases according to American Gas Association (AGA) Bulletin 36 and Weaver indices were investigated. BG-LPG mixed fuels were defined so as to have a Wobbe index (WI) nearly equivalent to those of natural gas (NG). The qualities of BG and LPG used are considered by varying the CH₄ and C₃H₈ percentage in the BG and LPG composition, respectively. It was found that BG-LPG mixed gases can not be used as interchangeable gases for natural gas and can not be applied to gas appliances for natural gas directly because of yellow-tipping and incomplete combustion. However, natural gas can be substituted for BG-LPG mixed gas completely and can be applied to gas appliances for BG-LPG mixed gas without any modification. On the other hand, BG-LPG mixed gases show interchangeability with itself without any unstable flame on gas appliances regardless of the components concentration variation.