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

Abstract 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 (CO 2 only) while those that favour incomplete combustion and high temperature produce CO, NO, and NO 2 as additional species if the natural gas contains no sulphur compounds. In the presence of H 2 S, SO 2 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 m 3 is predicted by the model to be 1.72×10 5 , 5.48×10 5 , 1.611×10 5 , 2.252×10 5 , and 1.16×10 3  kg for CO 2 , CO, NO, NO 2 , and SO 2 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.

[1]  I B Obioh,et al.  Non-CO2 gaseous emissions from upstream oil and gas operations in Nigeria , 1994, Environmental monitoring and assessment.

[2]  Gerhard Löffler,et al.  Catalytic effect of biomass ash on CO, CH4 and HCN oxidation under fluidised bed combustor conditions , 2002 .

[3]  K. Lyle,et al.  Experimental study of temperature and CH radical location in partially premixed CH4/air coflow flames , 1999 .

[4]  A. Salami,et al.  Implications of environmental degradation in Nigeria , 1996 .

[5]  A. O. Isichei,et al.  The Effects of Waste Gas Flares on the Surrounding Vegetation in South- Eastern Nigeria , 1976 .

[6]  D. Rainham,et al.  The role of air pollution in the relationship between a heat stress index and human mortality in Toronto. , 2003, Environmental research.

[7]  C E Kolb,et al.  Development of atmospheric tracer methods to measure methane emissions from natural gas facilities and urban areas. , 1995, Environmental science & technology.

[8]  Hermann Hofbauer,et al.  NO and N2O formation during the combustion of wood, straw, malt waste and peat , 1999 .

[9]  R. E. Schwartz,et al.  Predict radiation from flares , 1997 .

[10]  F. Akeredolu,et al.  Atmospheric environment problems in Nigeria—An overview , 1989 .

[11]  Johan E. Hustad,et al.  Scaling of nitric oxide emissions from buoyancy-dominated hydrocarbon turbulent-jet diffusion flames , 1992 .

[12]  János M. Beér,et al.  Minimizing NOx emissions from stationary combustion; reaction engineering methodology , 1994 .

[13]  D. Penney.  Carbon Monoxide Toxicity , 2000 .

[14]  F. Winter,et al.  Homogeneous formation of NO and N2O from the oxidation of HCN and NH3 at 600–1000°C , 2000 .

[15]  F. Billaud,et al.  Methane pyrolysis: thermodynamics , 1997 .

[16]  D. Spalding,et al.  INTRODUCTION TO COMBUSTION , 1979 .

[17]  S. Turns.  An Introduction to Combustion: Concepts and Applications , 2000 .

[18]  Forman A. Williams,et al.  NOx formation in two-stage methane–air flames , 1999 .