A theoretical prediction of non-methane gaseous emissions from natural gas combustion

In aviation industry, weather forecast is necessary to avert air disasters if flight must take place. In the crude oil producing sectors, there is a need also for a perfect knowledge of anticipated gaseous emissions from associated natural gas of known composition being flared on daily basis through combustion activities under several operating conditions. This will help in the control of gaseous emissions from these flares and thus in the protection of their immediate and distant environment against environmental degradation via air pollution. It is in the light of this that a theoretical model employing a set of material balance equations was investigated with natural gas of Nigerian origin as combustibles using a developed computer program. Operating conditions favouring complete combustion generate the least gaseous emission specie (CO2 only) while those that favour incomplete combustion and high temperature produce CO, NO, and NO2 as additional species if the natural gas contains no sulphur compounds. In the presence of H2S, SO2 is released in addition. The presence of other impurities, which are combustibles in the natural gas, might likely change these entirely. There is a strong correlation between emission quantity and amount of natural gas available for combustion. Carbon contents of the natural gas plays a prominent role in determination of quantity of air requires for combustion. This in turn determines the combustion reaction type (complete or incomplete). On the average, anticipated gaseous emission from natural gas of Nigerian origin with annual flaring rate of 25838.35 m3 is predicted by the model to be 1.72×105, 5.48×105, 1.611×105, 2.252×105, and 1.16×103 kg for CO2, CO, NO, NO2, and SO2 respectively. Confirmation of the presence of these gaseous pollutants from the various combustion reaction types investigated coupled with their overall high emission concentrations predicted are considered enough reasons for Nigerian Government to review its present natural gas policy. Routine flares in the country should be minimised for gaseous emission reduction.